title: Abundances in plantetary nebulae: Me 2-1

abstract:
  ISO and IUE spectra of the round planetary nebula Me 2-1 are combined with
visual spectra taken from the literature to obtain for the first time a
complete extinction-corrected spectrum. With this, the physico-chemical
characteristics of the nebula and its central star are determined by various
methods including photoionization modeling using Cloudy. The results of the
modeling are compared to those derived from a more classical, simple abundance
determination approach. A discussion is presented on the validity of the
different methods used and assumptions made. Finally, the main results are
interpreted in terms of the evolutionary stage of Me 2-1 and its central star.


title:
The Maxwell--Boltzmann gas with non-standard self--interactions: a novel
  approach to galactic dark matter

abstract:
  Using relativistic kinetic theory, we study spherically symmetric, static
equilibrium configurations of a collisionless Maxwell-Boltzmann gas with
non-standard self-interactions, modelled by an effective one--particle force.
The resulting set of equilibrium conditions represents a generalization of the
classical Tolman-Oppenheimer-Volkov equations. We specify these conditions for
two types of Lorentz--like forces: one coupled to the 4-acceleration and the
4--velocity and the other one coupled to the Riemann tensor. We investigate the
weak field limits in each case and show that they lead to various Newtonian
type configurations that are different from the usual isothermal sphere
characterizing the conventional Newtonian Maxwell--Boltzmann gas. These
configurations could provide a plausible phenomenological and theoretical
description of galactic dark matter halo structures. We show how the
self--interaction may act phenomenologically as an effective cosmological
constant and discuss possible connections with Modified Newtonian
Dynamics(MOND).


title:
XMM-Newton observations of the relaxed, high-redshift galaxy cluster
  ClJ0046.3+8530 at z=0.62

abstract:
  A detailed analysis of XMM observations of ClJ0046.3+8530 (z=0.624) is
presented. The cluster has a moderate temperature (kT=4.1+/-0.3keV) and appears
to be relaxed. Emission is detected at >3 sigma significance to a radius of 88%
of R200 (the radius enclosing an overdensity of 200 times the critical density
at z=0.624) in a surface-brightness profile. A temperature profile (extending
to 0.7R200), and hardness-ratio map show no significant departures from the
global temperature, within the statistical limits of the data. The cluster's
bolometric X-ray luminosity is L=(4.3+/-0.3)*10^44 erg/s, and the total mass
derived within R200, assuming isothermality and hydrostatic equilibrium, is
M_200=3.0^{+0.6}_{-0.5}*10^14 Msolar. The gas entropy measured at 0.1R200 is
compared with a sample of local systems, and found to be consistent with
self-similar evolution with redshift. The metallicity, gas density profile
slope, and gas mass fraction are all consistent with those found in low-z
clusters.


title: Latest results of the EDELWEISS experiment

abstract:
  The EDELWEISS experiment is a direct detection Dark Matter Search, under the
form of WIMPs. It uses heat and ionization Ge cryogenic detectors. We present
the latest results obtained by the experiment with three new 320g bolometers.
At present, EDELWEISS I is the most sensitive experiment for all WIMP masses
compatible with accelerator constraints (Mwimp>30 GeV/c^2). We also briefly
describe the status of the second stage EDELWEISS II involving initially 10 kg
of detectors aiming a gain of two orders of magnitude in sensitivity.


title:
Beppo-SAX temperature maps of galaxy clusters in the Corona Borealis
  supercluster: A2061, A2067 and A2124

abstract:
  In this paper we present the analysis of Beppo-SAX observations of the
cluster pairs A2061-A2067 and A2122-A2124, located in the Corona Borealis
supercluster, which have been selected as candidate merging clusters. The aim
of this work is to study the physics of the intracluster medium and to look for
the possible presence of merging signatures.
  We derived the global temperatures and abundances and the temperature
profiles and maps for these clusters. We do not find any significant evidence
of interaction between the clusters forming the pairs, but we detect a
candidate shock inside A2061. On the basis of the X-ray and optical properties
of this cluster we propose a scenario in which a group is falling inside A2061.
This interaction is in the phase in which the cores have not encountered yet
and in which the formation of a shock is expected.


title: A highly collimated, extremely high velocity outflow in Taurus

abstract:
  We present the first case of a highly collimated, extremely high velocity
bipolar outflow in Taurus. It is powered by the low-luminosity (0.4 L_sun)
source IRAS 04166+2706 and contains gas accelerated up to 50 km/s with respect
to the ambient cloud both toward the blue and the red (uncorrected for
projection). At the highest velocities, the outflow collimation factor exceeds
20, and the gas displays a very high degree of spatial symmetry. This very fast
gas presents multiple maxima, and most likely arises from the acceleration of
ambient material by a time-variable jet-like stellar wind. When scaled for
luminosity, the outflow parameters of IRAS 04166 are comparable to those of
other extremely high velocity outflows like L1448, indicating that even the
very quiescent star-formation mode of Taurus can produce objects powering very
high energy flows (L_mec/L_* > 0.15).


title:
Influence of UV radiation from a massive YSO on the chemistry of its
  envelope

abstract:
  We have studied the influence of far ultraviolet (UV) radiation from a
massive young stellar object (YSO) on the chemistry of its own envelope by
extending the models of Doty et al. (2002) to include a central source of UV
radiation. The models are applied to the massive star-forming region AFGL 2591
for different inner UV field strengths. Depth-dependent abundance profiles for
several molecules are presented and discussed. We predict enhanced column
densities for more than 30 species, especially radicals and ions. Comparison
between observations and models is improved with a moderate UV field incident
on the inner envelope, corresponding to an enhancement factor G0~10-100 at 200
AU from the star with an optical depth tau~15-17. Subtle differences are found
compared with traditional models of Photon Dominated Regions (PDRs) because of
the higher temperatures and higher gas-phase H2O abundance caused by
evaporation of ices in the inner region. In particular, the CN/HCN ratio is not
a sensitive tracer of the inner UV field, in contrast with the situation for
normal PDRs: for low UV fields, the extra CN reacts with H2 in the inner dense
and warm region and produces more HCN. It is found that the CH+ abundance is
strongly enhanced and grows steadily with increasing UV field. High-J lines of
molecules like CN and HCN are most sensitive to the inner dense region where UV
radiation plays a role. Thus, even though the total column density affected by
UV photons is small, comparison of high-J and low-J lines can selectively trace
and distinguish the inner UV field from the outer one. In addition, future
Herschel-HIFI observations of hydrides can sensitively probe the inner UV
field.


title:
Weak lensing study of dark matter filaments and application to the
  binary cluster A 222 and A 223

abstract:
  We present a weak lensing analysis of the double cluster system Abell 222 and
Abell 223. The lensing reconstruction shows evidence for a possible dark matter
filament connecting both clusters. The case for a filamentary connection
between A 222/223 is supported by an analysis of the galaxy density and X-ray
emission between the clusters. Using the results of N-body simulations, we try
to develop a criterion that separates this system into cluster and filament
regions. The aim is to find a technique that allows the quantification of the
significance of (weak lensing) filament candidates in close pairs of clusters.
While this mostly fails, the aperture quadrupole statistics (Schneider &
Bartelmann 1997) shows some promise in this area. The cluster masses determined
from weak lensing in this system are considerably lower than those previously
determined from spectroscopic and X-ray observations (Dietrich et al. 2002;
Proust et al. 2000; Wang et al. 1999). Additionally, we report the
serendipitous weak lensing detection of a previously unknown cluster in the
field of this double cluster system.


title: The pre-main sequence binary HK Ori : Spectro-astrometry and EXPORT data

abstract:
  In this paper we present multi-epoch observations of the pre-main sequence
binary HK Ori. These data have been drawn from the EXPORT database and are
complemented by high quality spectro-astrometric data of the system. The
spectroscopic data appear to be very well represented by a combination of an A
dwarf star spectrum superposed on a (sub-)giant G-type spectrum. The radial
velocity of the system is consistent with previous determinations, and does not
reveal binary motion, as expected for a wide binary. The spectral, photometric
and polarimetric properties and variability of the system indicate that the
active object in the system is a T Tauri star with UX Ori characteristics. The
spectro-astrometry of HK Ori is sensitive down to milli-arcsecond scales and
confirms the speckle interferometric results from Leinert et al. The
spectro-astrometry allows with fair certainty the identification of the active
star within the binary, which we suggest to be a G-type T Tauri star based on
its spectral characteristics.


title: Evidence for a warm ISM in Fornax dEs - II. FCC032, FCC206 and FCCB729

abstract:
  We present R-band and H-alpha+[N II] narrow-band imaging of FCC032, FCC206
and FCCB729, three dwarf elliptical galaxies (dEs) in the Fornax Cluster. These
dEs contain significant amounts of ionized gas. FCC032 harbours a large ionized
gas complex, consisting of several individual clouds, a superbubble and a
filament that extends away from the galaxy centre. The ionized gas structures
observed in FCC032 bear a strong resemblance to those observed in more gas-rich
and more fiercely star-forming dwarf galaxies. FCC206, a very low surface
brightness dE, contains one faint extended emission region, and two compact
clouds. In FCCB729, the only nucleated galaxy in this sample, one of the
ionized gas clouds coincides with the stellar nucleus. We derive ionized gas
masses of a few 100 to 1000 solar masses for these galaxies. This brings our
sample of dEs with ionized gas with H-alpha+[N II] narrow-band imaging to five
objects. The ionized gas morphologies in these galaxies range from pure nuclear
emission peaks to extended emission complexes. This morphological diversity
could also indicate a diversity in ionizing processes in dEs with a warm
interstellar medium (active galactic nuclei, starbursts, post-AGB stars,...).
Inside FCC206, four star clusters appear to be on the verge of merging to form
a nucleus in this presently non-nucleated dE. Understanding the formation of
nuclei in dEs could give us important clues to the formation of super-massive
black holes.


title:
Statistical features of 21-cm emission from the epoch between
  reionization and Gunn-Peterson transparency

abstract:
  We investigate the 21 cm emission from the epoch between reionization z_r and
Gunn-Peterson transparency z_{gp}. According to the lognormal model of the
thermal history around reionization, hydrogen clouds in z_r > z > z_{gp} are
hot and a predominant part of baryonic gas is ionized, but still opaque to
Ly-alpha photons. Therefore, 21 cm emission is a distinctive characteristic of
this epoch. We show that the 21 cm emission comes from both uncollapsed and
collapsing hydrogen clouds. The spatial distribution of the brightness
temperature excess $\delta T_b$ is highly non-Gaussian. It consists of spikes
with high $\delta T_b$ and a low $\delta T_b$ area between the spikes. The
field has the following statistical features: (1) the one-point distributions
of $\delta T_b$ are described approximately by power-law tailed probability
distribution functions; (2) the nth-order moment of $\delta T_b$ is increasing
much faster with n than that of a Gaussian field, but slower than that of a
lognormal field; (3) the scale-scale correlation of the $\delta T_b$ field is
significant for all scales larger than the Jeans length of the gas. These
features would be useful for distinguishing the 21 cm emission of the early
clustering from the noise of foreground contamination.


title:
Measuring mass and angular momentum of black holes with high-frequency
  quasi-periodic oscillations

abstract:
  3:2 and/or 3:1 twin high frequency quasi-periodic oscillations (HFQPOs) have
been measured for the three microquasars GRO J1655-40, XTE J1550-564 and GRS
1915+105. For a test particle orbiting a rotating black on a stable circular
orbit there exist two different orbits at which the vertical and radial
epicyclic oscillations are in either a 3:1 or 3:2 parametric resonance for any
choice of the black hole angular momentum $a$. If the two orbits are required
to be frequency commensurable Keplerian orbits there is only one solution for
the two orbit radii and $a$. This model predicts that the microquasars have the
same $a$, and it predicts their black hole masses on the basis of the measured
HFQPOs in agreement with the dynamically determined masses. Application of this
model to the Galactic Center black hole Sgr A* using the recently measured QPOs
(Genzel et al., 2003, Aschenbach et al., 2004) leads to a black hole mass of
(3.28 +/- 0.13) x 10^6 M_odot, and the same $a$ as for the microquasars. The
possibility that all four sources have $a$=0.99616 suggests that this value is
the upper limit of $a$ imposed by general relativity. The same value for the
lower orbit radius and the same value for $a$ are also suggested by an analysis
of the general relativistic expression for the radial gradient of the orbital
velocity, which changes sign in a narrow annular region around the lower orbit
when $a$>0.9953.


title:
The Hubble Higher-Z Supernova Search: Supernovae to z=1.6 and
  Constraints on Type Ia Progenitor Models

abstract:
  We present results from the Hubble Higher-z Supernova Search, the first
space-based open field survey for supernovae (SNe). In cooperation with the
Great Observatories Origins Deep Survey, we have used the Hubble Space
Telescope with the Advanced Camera for Surveys to cover 300 square arcmin in
the area of the Chandra Deep Field South and the Hubble Deep Field North on
five separate search epochs (separated by 45 day intervals) to a limiting
magnitude of z'=26. These deep observations have allowed us to discover 42 SNe
in the redshift range 0.2 < z < 1.6. As these data span a large range in
redshift, they are ideal for testing the validity of Type Ia supernova
progenitor models with the distribution of expected ``delay times,'' from
progenitor star formation to SN Ia explosion, and the SN rates these models
predict. Through a Bayesian maximum likelihood test, we determine which
delay-time models best reproduce the redshift distribution of SNe Ia discovered
in this survey. We find that models that require a large fraction of ``prompt''
(less than 2 Gyr) SNe Ia poorly reproduce the observed redshift distribution
and are rejected at 95% confidence. We find that Gaussian models best fit the
observed data for mean delay times in the range of 3 to 4 Gyr.


title: High Redshift Supernova Rates

abstract:
  We use a sample of 42 supernovae detected with the Advanced Camera for
Surveys on-board the Hubble Space Telescope as part of the Great Observatories
Origins Deep Survey to measure the rate of core collapse supernovae to z~0.7
and type Ia supernovae to z~1.6. This significantly increases the redshift
range where supernova rates have been estimated from observations.
  The rate of core collapse supernovae can be used as an independent probe of
the cosmic star formation rate. Based on the observations of 17 core collapse
supernovae, we measure an increase in the core collapse supernova rate by a
factor of 1.6 in the range 0.3<z<0.7, and an overall increase by a factor of 7
to z~0.7 in comparison to the local core collapse supernova rate. The increase
in the rate in this redshift range in consistent with recent measurements of
the star formation rate derived from UV-luminosity densities and IR datasets.
  Based on 25 type Ia supernovae, we find a SN Ia rate that is a factor 3-5
higher at z~1 compared to earlier estimates at lower redshifts (z<0.5),
implying that the type Ia supernova rate traces a higher star formation rate at
redshifts z>1 compared to low redshift. At higher redshift (z>1), we find a
suggested decrease in the type Ia rate with redshift. This evolution of the Ia
rate with redshift is consistent with a type Ia progenitor model where there is
a substantial delay between the formation of the progenitor star and the
explosion of the supernova. Assuming that the type Ia progenitor stars have
initial main sequence masses 3-8 M_Sun, we find that 5-7% of the available
progenitors explode as type Ia supernovae.


title:
Why soft X-ray transients can remain in the low/hard state during
  outburst

abstract:
  In the canonical understanding of transient X-ray sources the accretion
during quiescence occurs via a geometrically thin disk in the outer part and
via an advection-dominated hot coronal flow/ADAF in the inner part. The inner
part important for the radiation yields a hard spectrum. In most sources the
luminosity increase during outburst causes a change over to a soft spectrum
which can be understood as that of a multi-color black body disk reaching
inward to the marginally stable orbit. A few transient sources do not display
this transition to the soft state. We show that this can be understood as due
to relatively low peak luminosities in outburst in systems with short orbital
periods and therefore less mass accumulated in the then smaller accretion disk.
This is in agreement with the observations which show that most likely short
orbital period systems remain in the hard spectral state.


title: Dust temperatures in asymmetric prestellar cores

abstract:
  We present 2D Monte Carlo radiative transfer simulations of flattened
prestellar cores. We argue the importance of observing prestellar cores near
the peak of their emission spectra, and we point out observable characteristic
features on isophotal maps of asymmetric cores at FIR wavelengths that are
indicative of the cores' density and temperature structure. These features are
on scales 1/5 to 1/3 of the overall core size, and so high resolution
observations are needed to observe them. Finally, we discuss the importance of
determining the temperatures of prestellar cores with high accuracy.


title: The Ecology of Black Holes in Star Clusters

abstract:
  In this lecture we investigate the formation and evolution of black holes in
star clusters. The star clusters under consideration are generally rich,
containing more than 10^4 stars, and with a density exceeding 10^4 stars/pc^3.
Among these are young dense clusters (YoDeCs), globular cluster and the nuclei
of galaxies. We will also address the the possible evolutionary link between
stellar mass black holes, via intermediate mass black holes to supermassive
black holes, mainly focus on the ecology of star clusters.


title: Menzel 3: Dissecting the ant

abstract:
  The structure and kinematics of the bipolar nebula Mz 3 have been
investigated by means of HST, CTIO and ESO images and spectra. At least four
distinct outflows have been identified which, from the inside to the outside,
are the following: a pair of bright bipolar lobes, two opposite highly
collimated column-shaped outflows, a conical system of radial structure, and a
very dim, previously unnoticed, low-latitude and flattened (ring-like) radial
outflow.
  A simple Hubble-law describes the velocity field of the ballisticaly
expanding lobes, columns and rays, suggesting that their shaping has being done
at very early stages of evolution, in a sort of eruptive events with increasing
degree of collimation and expansion ages ranging from ~600 for the inner
structures to ~1600 years (per kpc to the nebula) for the largest ones.


title: Stellar evolution with rotation XII: Pre-supernova models

abstract:
  We describe the latest developments of the Geneva stellar evolution code in
order to model the pre-supernova evolution of rotating massive stars. Rotating
and non-rotating stellar models at solar metallicity with masses equal to 12,
15, 20, 25, 40 and 60 solar masses were computed from the ZAMS until the end of
the core silicon burning phase. We took into account meridional circulation,
secular shear instabilities, horizontal turbulence and dynamical shear
instabilities.
  Most of the differences between the pre-supernova structures obtained from
rotating and non-rotating stellar models have their origin in the effects of
rotation during the core hydrogen and helium burning phases.
  The effects of rotation on pre-supernova models are significant between 15
and 30 solar masses. Indeed, rotation increases the core sizes (and the yields)
by a factor ~ 1.5. Above 20 solar masses, rotation may change the colour of the
supernova progenitors (blue instead of red supergiant) and the supernova type
(Ib instead of II). Rotation affects the lower mass limits for radiative core
carbon burning, for iron core collapse and for black hole formation. For
Wolf-Rayet stars (M > 30 solar masses), the pre-supernova structures are mostly
affected by the intensities of the stellar winds and less by rotational mixing.
Finally, the core of our rotating WR stars contain enough angular momentum to
produce GRBs.


title: INTEGRAL and XMM-Newton Spectral Studies of NGC 4388

abstract:
  We present first INTEGRAL and XMM-Newton observations of a Seyfert galaxy,
the type 2 AGN NGC 4388. Several INTEGRAL observations performed in 2003 allow
us to study the spectrum in the 20 - 300 keV range. In addition two XMM-Newton
observations give detailed insight into the 0.2 - 10 keV emission. The
measurements presented here and comparison with previous observations by
BeppoSAX, SIGMA and CGRO/OSSE show that the overall spectrum from soft X-rays
up to the gamma-rays can be described by a highly absorbed (N_H = 2.7e23
1/cm^2) and variable non-thermal component in addition to constant non-absorbed
thermal emission (T = 0.8 keV) of low abundance (7% solar), plus a constant Fe
K-alpha and K-beta line. The hard X-ray component is well described by a simple
power law with a mean photon index of 1.7. During the INTEGRAL observations the
20 - 100 keV flux increased by a factor of 1.4. The analysis of XMM-Newton data
implies that the emission below 3 keV is decoupled from the AGN and probably
due to extended emission as seen in Chandra observations. The constant iron
line emission is apparently also decoupled from the direct emission of the
central engine and likely to be generated in the obscuring material, e.g. in
the molecular torus.


title: Feedback Processes at Cosmic Dawn

abstract:
  The consequences of energy injection associated with stellar activity in
galaxies have been often referred to as ``feedback effects''. Assessing the
detailed physics and the role of such effects are central issues in modern
theories of galaxy formation and evolution. In these Lectures we present a
brief review of various aspects related to feedback with particular emphasis to
those occurring when the universe was only 100 Myr old, an epoch now commonly
known as the the Cosmic Dawn, when the first galaxies and the stars within them
brought the universe back into the visible ages.


title:
Extended GeV-TeV Emission around Gamma-Ray Burst Remnants, and the Case
  of W49B

abstract:
  We investigate the high-energy photon emission around Gamma-Ray Burst (GRB)
remnants caused by ultrahigh-energy cosmic rays (UHECRs) from the GRBs. We
apply the results to the recent report that the supernova remnant W49B is a GRB
remnant in our Galaxy. If this is correct, and if GRBs are sources of UHECRs, a
natural consequence of this identification would be a detectable TeV photon
emission around the GRB remnant. The imaging of the surrounding emission could
provide new constraints on the jet structure of the GRB.


title: The Size Distribution of Kuiper Belt Objects

abstract:
  We describe analytical and numerical collisional evolution calculations for
the size distribution of icy bodies in the Kuiper Belt. For a wide range of
bulk properties, initial masses, and orbital parameters, our results yield
power-law cumulative size distributions, N_C propto r^{-q}, with q_L = 3.5 for
large bodies with radii of 10-100 km, and q_s = 2.5-3 for small bodies with
radii lesss than 0.1-1 km. The transition between the two power laws occurs at
a break radius of 1-30 km. The break radius is more sensitive to the initial
mass in the Kuiper Belt and the amount of stirring by Neptune than the bulk
properties of individual Kuiper Belt objects (KBOs). Comparisons with
observations indicate that most models can explain the observed sky surface
density of KBOs for red magnitudes, R = 22-27. For R < 22 and R > 28, the model
surface density is sensitive to the amount of stirring by Neptune, suggesting
that the size distribution of icy planets in the outer solar system provides
independent constraints on the formation of Neptune.


title:
Properties of the warm magnetized ISM, as inferred from WSRT
  polarimetric imaging

abstract:
  We describe a first attempt to derive properties of the regular and turbulent
Galactic magnetic field from multi-frequency polarimetric observations of the
diffuse Galactic synchrotron background. A single-cell-size model of the thin
Galactic disk is constructed which includes random and regular magnetic fields
and thermal and relativistic electrons. The disk is irradiated from behind with
a uniform partially polarized background. Radiation from the background and
from the thin disk is Faraday rotated and depolarized while propagating through
the medium. The model parameters are estimated from a comparison with 350 MHz
observations in two regions at intermediate latitudes done with the Westerbork
Synthesis Radio Telescope. We obtain good consistency between the estimates for
the random and regular magnetic field strengths and typical scales of structure
in the two regions. The regular magnetic field strength found is a few
microGauss, and the ratio of random to regular magnetic field strength is 0.7
+/- 0.5, for a typical scale of the random component of 15 +/- 10 pc.
Furthermore, the regular magnetic field is directed almost perpendicular to the
line of sight. This modeling is a potentially powerful method to estimate the
structure of the Galactic magnetic field, especially when more polarimetric
observations of the diffuse synchrotron background at intermediate latitudes
become available.


title:
QSO size ratios from multiband monitoring of a microlensing
  high-magnification event

abstract:
  We introduce a new scheme to study the nature of the central engine in a
lensed QSO. The compact emission regions could have different sizes in
different optical wavelengths, and our framework permits to obtain the source
size ratios when a microlensing special high-magnification event (e.g., a
caustic crossing event, a two-dimensional maximum crossing event and so on) is
produced in one of the QSO components. To infer the source size ratios, only
cross-correlations between the brightness records in different optical bands
are required. While the deconvolution method leads to a richer information (1D
intrinsic luminosity profiles), the new approach is free of the technical
problems with complex inversion procedures. Using simulations related to recent
VR data of Q2237+0305A, we discuss the ability of the scheme in the
determination of the visible-to-red ratio q = $R_V/R_R$. We conclude that
extremely accurate fluxes (with a few microJy uncertainties, or equivalently, a
few milli-magnitudes errors) can lead to ~10% measurements of q. Taking into
account the errors in the fluxes of Q2237+0305A from a normal ground-based
telescope, ~10 microJy (~10 mmag), it must be possible the achievement of
smaller errors from the current superb-telescopes, and thus, an accurate
determination of q. Obviously, to measure the visible-to-red ratio, the light
curves cannot be contaminated by an intrinsic event or an important
high-frequency intrinsic signal, i.e., exceeding the microJy (mmag) level. For
an arbitrary lensed QSO, we finally remark that the framework seems to work
better with very fast microlensing events.


title:
Near Infrared Spectroscopy of High Redshift Active Galactic Nuclei. I. A
  Metallicity-Accretion Rate Relationship

abstract:
  We present new near infrared spectroscopic measurements of the H_beta region
for a sample of 29 luminous high redshift quasars. We have measured the width
of H_beta in those sources, and added archival H_beta width measurements, to
create a sample of 92 active galactic nuclei (AGNs) for which H_beta width and
rest-frame UV measurements of N V \lambda 1240 and C IV \lambda 1549
emission-lines are available. Our sample spans six orders of magnitude in
luminosity and includes 31 radio-loud AGNs. It also includes 10 narrow-line
Seyfert 1 galaxies and one broad absorption-line quasar. We find that
metallicity, indicated by the N V/C IV line ratio, is primarily correlated with
accretion rate, which is a function of luminosity and H_beta line-width. This
may imply an intimate relation between starburst, responsible for the metal
enrichment of the nuclear gas, and AGN fueling, represented by the accretion
rate. The correlation of metallicity with luminosity, or black hole (BH) mass,
is weaker in contrast with recent results which were based on measurements of
the width of C IV. We argue that using C IV as a proxy to H_beta in estimating
M_BH might be problematic and lead to spurious BH mass and accretion rate
estimates in individual sources. We discuss the potential implications of our
new result in the framework of the starburst-AGN connection and theories of BH
growth.


title:
Near Infrared Spectroscopy of High Redshift Active Galactic Nuclei. II.
  Disappearing Narrow Line Regions and the Role of Accretion

abstract:
  We present new near infrared spectroscopic measurements for 29 luminous
high-z quasars and use the data to discuss the size and other properties of the
NLRs in those sources. The high resolution spectra have been used to carefully
model the Fe II blends and to provide reliable [O III], Fe II and Hb
measurements. We find that about 2/3 of all high luminosity sources show strong
[O III] lines while the remaining objects show no or very weak such line. While
weak [O III] emitters are also found among lower luminosity AGN, we argue that
the implications for very high luminosity objects are different. In particular,
we suggest that the averaging of these two populations in other works gave rise
to claims of a Baldwin relationship in [O III] which is not confirmed by our
data. We also argue that earlier proposed relations of the type R_NLR \propto
L_[O III]^{1/2}, where R_NLR is the NLR radius, are theoretically sound yet
they must break down for R_NLR exceeding a few kpc. This suggests that the NLR
properties in luminous sources are different from those observed in nearby AGN.
In particular, we suggest that some sources lost their very large, dynamically
unbound NLR while others are in a phase of violent star-forming events that
produce a large quantity of high density gas in the central kpc. This gas is
ionized and excited by the central radiation source and its spectroscopic
properties may be different from those observed in nearby, lower luminosity
NLRs. We also discuss the dependence of EW(Hb) and Fe II/Hb on L, M_BH, and
accretion rate for a large sample of AGNs. The strongest dependence of the two
quantities is on the accretion rate and the Fe II/Hb correlation is probably
due to the EW(Hb) dependence on accretion rate. We show the most extreme values
measured so far of Fe II/Hb and address its correlation with EW([O III]).


title: The X-ray Spectrum of the z=6.30 QSO SDSS J1030+0524

abstract:
  We present a deep XMM-Newton observation of the z=6.30 QSO SDSS J1030+0524,
the second most distant quasar currently known. The data contain sufficient
counts for spectral analysis, demonstrating the ability of XMM-Newton to
measure X-ray spectral shapes of z~6 QSOs with integration times >100ks. The
X-ray spectrum is well fit by a power law with index Gamma=2.12 +/- 0.11, an
optical-X-ray spectral slope of a_{ox}=-1.80, and no absorption excess to the
Galactic value, though our data are also consistent with a power law index in
the range 2.02 < Gamma < 2.5 and excess absorption in the range 0 < N_H(cm^-2)
< 8x10^22. There is also a possible detection (2 sigma) of FeKa emission. The
X-ray properties of this QSO are, overall, similar to those of lower-redshift
radio-quiet QSOs. This is consistent with the statement that the X-ray
properties of radio-quiet QSOs show no evolution over 0<z<6.3. Combined with
previous results, this QSO appears indistinguishable in any way from lower
redshift QSOs, indicating that QSOs comparable to those seen locally existed
less than one Gyr after the Big Bang.


title:
Galaxy Size Evolution at High Redshift and Surface Brightness Selection
  Effects: Constraints from the Hubble Ultra Deep Field

abstract:
  We use the exceptional depth of the Ultra Deep Field (UDF) and UDF-Parallel
ACS fields to study the sizes of high redshift (z~2-6) galaxies and address
long-standing questions about possible biases in the cosmic star formation rate
due to surface brightness dimming. Contrasting B, V, and i-dropout samples
culled from the deeper data with those obtained from the shallower GOODS
fields, we demonstrate that the shallower data are essentially complete at
bright magnitudes to z<5.5 and that the principal effect of depth is to add
objects at the magnitude limit. This indicates that high redshift galaxies are
compact in size (~0.1-0.3") and that large (>0.4", >3 kpc) low surface
brightness galaxies are rare. A simple comparison of the half-light radii of
the HDF-N + HDF-S U-dropouts with B, V, and i-dropouts from the UDF shows that
the sizes follow a (1+z)^{-1.05+/-0.21} scaling towards high redshift. A more
rigorous measurement compares different scalings of our U-dropout sample with
the mean profiles for a set of intermediate magnitude (26.0<z_{850,AB}<27.5)
i-dropouts from the UDF. The best-fit is found with a (1+z)^{-0.94_{-0.25}
^{+0.19}} size scaling (for fixed luminosity). This result is then verified by
repeating this experiment with different size measures, low redshift samples,
and magnitude ranges. Very similar scalings are found for all comparisons. A
robust measurement of size evolution is thereby demonstrated for galaxies from
z~6 to z~2.5 using data from the UDF.


title:
Distribution of mass in galaxy cluster CL0024 and the particle mass of
  dark matter

abstract:
  We study in details the distribution of mass in galaxy cluster CL0024+1654
inferred using the method of strong gravitational lensing by Tyson {\it et al.}
(1998). We show that a linear correlation exists between total, visible and
dark matter distributions on log-log scale with consistent coefficients. The
shape and parameters of log-log-linear correlation are not affected
significantly whether one uses projected or volume mass densities but is
consistent with $\kappa=2-5$ visible/dark ratio. We also show and analyze in
depth so called alignment properties of the above-mentioned profiles. We show
that log-log-linear correlation and alignments can all be understood in terms
of thermodynamic/hydrodynamic equilibrium with gravitational potential growing
almost linearly in the region of interest. We then analyze the hypothesis of
thermal equilibrium on the base of the existing data about CL0024 cluster. If
the presence of log-log-linear correlation and alignments were interpreted
thermodynamically, this would indicate the mass of the dark matter particle 2-5
times smaller than that of atomic hydrogen, thus giving range for the mass of
dark matter particle between 200MeV and 1000MeV.


title:
Globular Cluster and Galaxy Formation: M31, the Milky Way and
  Implications for Globular Cluster Systems of Spiral Galaxies

abstract:
  The globular cluster (GC) systems of the Milky Way and of our neighboring
spiral galaxy, M31, comprise 2 distinct entities, differing in 3 respects. 1.
M31 has young GCs, ages from ~100 Myr to 5 Gyr old, as well as old globular
clusters. No such young GCs are known in the Milky Way. 2. We confirm that the
oldest M31 GCs have much higher nitrogen abundances than do Galactic GCs at
equivalent metallicities. 3. Morrison et al. found M31 has a subcomponent of
GCs that follow closely the disk rotation curve of M31. Such a GC system in our
own Galaxy has yet to be found. These data are interpreted in terms of the
hierarchical-clustering-merging (HCM) paradigm for galaxy formation. We infer
that M31 has absorbed more of its dwarf systems than has the Milky Way. This
inference has 3 implications: 1. All spiral galaxies likely differ in their GC
properties, depending on how many companions each galaxy has, and when the
parent galaxy absorbs them. The the Milky Way ties down one end of this
spectrum, as almost all of its GCs were absorbed 10-12 Gyr ago. 2. It suggests
that young GCs are preferentially formed in the dwarf companions of parent
galaxies, and then absorbed by the parent galaxy during mergers. 3. Young GCs
seen in tidally-interacting galaxies might come from dwarf companions of these
galaxies, rather than be made a-new in the tidal interaction. There is no ready
explanation for the marked difference in nitrogen abundance for old M31 GCs
relative to the oldest Galactic GCs. The predictions made by Li & Burstein
regarding the origin of nitrogen abundance in globular clusters are consistent
with what is found for the old M31 GCs compared to that for the two 5 Gyr-old
M31 GCs.


title:
Simultaneous Constraints on the Spectrum of the Extragalactic Background
  Light and the Intrinsic Tev Spectra of Mrk 421, Mrk 501, and H1426+428

abstract:
  Very high energy (~ TeV) $\gamma$-rays from blazars are attenuated by photons
from the extragalactic background light (EBL). Observations of blazars can
therefore provide an ideal opportunity for determining the EBL intensity if
their intrinsic spectrum is known. Conversely, knowledge of the EBL intensity
can be used to determine the intrinsic blazar spectrum. Unfortunately, neither
the EBL intensity nor the intrinsic blazar spectrum is known with high enough
precision to accurately derive one quantity from the other. In this paper we
use the most recent data on the EBL to construct twelve different realizations
representing all possible permutations between EBL limits and the detections in
the different wavelength regions. We use these realizations to explore the
effects of the EBL on the inferred spectra of blazars. In particular, we show
that the frequently cited "IR background-TeV gamma-ray crisis" does not exist,
and derive the intrinsic spectra and peak energies of the blazars Mrk 421, 501
and H1426+428 for EBL realizations that give rise to physically viable
intrinsic blazar spectra. We also show that the intrinsic spectrum of Mrk~421
during a period of intense flaring activity has a peak energy that seems to
shift to higher energies at higher flux states. Finally, we also explore the
effect of the uncertainties in the absolute calibration of the gamma-ray
energies on derived TeV opacities and the intrinsic blazar spectra.


title: Sub-arcsecond sub-mm continuum observations of Orion-KL

abstract:
  We present the first 865 mu continuum image with sub-arcsecond resolution
obtained with the Submillimeter Array. These data resolve the Orion-KL region
into the hot core, the nearby radio source I, the sub-mm counterpart to the
infrared source n (radio source L), and new sub-mm continuum sources. The radio
to submillimeter emission from source I may be modeled as either the result of
proton-electron free-free emission that is optically thick to ~100 GHz plus
dust emission that accounts for the majority of the submillimeter flux, or H-
free-free emission that gives rise to a power-law spectrum with power-law index
of ~1.6. The latter model would indicate similar physical conditions as found
in the inner circumstellar environment of Mira variable stars. Future
sub-arcsecond observations at shorter sub-mm wavelengths should easily
discriminate between these two possibilities. The sub-mm continuum emission
toward source n can be interpreted in the framework of emission from an
accretion disk.


title: Cosmic Background Radiation Mini-Review

abstract:
  This is a complete re-write of the mini-review for the Review of Particle
Physics (a.k.a the Partcicle Data Book), which includes an assessment of the
CMB anisotropy results and their interpretation up until the end of 2003. It
forms a compact overview of the field at this time. Sections headings are:
Introduction; Description of CMB Anisotropies; Cosmological Parameters; Physics
of Anisotropies; Current Anisotropy Data; CMB Polarization; Complications;
Constraints on Cosmologies; Particle Physics Constraints; Fundamental Lessons;
and Future Directions.


title:
Gravitational Lensing Signatures of Supermassive Black Holes in Future
  Radio Surveys

abstract:
  Observational measurements of the relationship between supermassive black
holes (SMBHs) and the properties of their host galaxies are an important method
for probing theoretical hierarchical growth models. Gravitational lensing is a
unique mechanism for acquiring this information in systems at cosmologically
significant redshifts. We review the calculations required to include SMBHs in
two standard galactic lens models, a cored isothermal sphere and a broken power
law. The presence of the SMBH produces two primary effects depending on the
lens configuration, either blocking the ``core'' image that is usually
predicted to form from a softened lens model, or adding an extra, highly
demagnified, image to the predictions of the unaltered lens model. The
magnitudes of these effects are very sensitive to galaxy core sizes and SMBH
masses. Therefore, observations of these lenses would probe the properties of
the inner regions of galaxies, including their SMBHs. Lensing cross-sections
and optical depth calculations indicate that in order to fully observe these
characteristic signatures, flux ratios of order 10^6 or more between the
brightest and faintest images of the lens must be detectable, and thus the next
generation of radio telescope technology offers the first opportunity for a
serious observational campaign. Core images, however, are already detectable
and with additional observations their statistics may be used to guide future
SMBH searches.


title: MERLIN and VLA Observations of VII Zw 19: Distant Cousin of M82

abstract:
  We have observed the starburst dwarf galaxy VII Zw 19 at subarcsecond
resolution with the MERLIN and MERLIN+EVN networks at 18 cm, with MERLIN at 6
cm, and with the VLA in A array at 6 and 2 cm. The galaxy is detected at all
VLA wavelengths and is resolved. It is also resolved at 18 cm by MERLIN, but is
not detected by the EVN nor by MERLIN at 6 cm.
  VII Zw 19 has a complex structure of nonthermal radio emission at 18 cm
extended over ~1200-1800 pc (4-6''). That the EVN did not detect this emission
indicates that there are no obvious point sources that could be radio
supernovae. The 2 cm emission, predominantly thermal free-free emission, has a
markedly different spatial distribution from the nonthermal emission. The radio
colors show that the galaxy contains numerous supernova remnants, as well as
many young HII regions, many of which are optically thick at 6 cm. Two extended
regions of 2 cm emission have little 18 cm flux and are probably emission from
young star clusters. VII Zw 19 resembles M82 in its radio and infrared
spectrum, but the starburst region in VII Zw 19 is twice the size of the one in
M82 and twice as luminous.


title:
Are the jets accelerated from the disk coronas in some active galactic
  nuclei?

abstract:
  We use a sample of radio-loud active galactic nuclei (AGNs) with estimated
central black hole masses to explore their jet formation mechanisms. The jet
power of AGNs is estimated from their extended radio luminosity. It is found
that the jets in several AGNs of this sample are too powerful to be extracted
from the standard thin accretion disks or rapidly spinning black holes
surrounded by standard thin disks. If the advection dominated accretion flows
(ADAFs) are present in these AGNs, their bright optical continuum luminosity
cannot be produced by pure-ADAFs due to their low accretion rates and low
radiation efficiency, unless the ADAFs transit to standard thin disks at some
radii $R_{\rm tr}$. If this is the case, we find that the dimensionless
accretion rates as high as 0.05 and transition from ADAFs to standard thin
disks at rather small radii around 20GM/c^2 are required to explain their
bright optical continuum emission. We propose that the disk-corona structure is
present at least in some AGNs in this sample. The plasmas in the corona are
very hot, and the pressure scale-height of the corona H\sim R. Powerful jets
with Q_jet \sim L_bol (bolometric luminosity) can form by the large-scale
magnetic fields created by dynamo processes in the disk corona of some AGNs.
The maximal jet power extractable from the corona Q_jet^max\le 0.6L_c (L_c is
the corona luminosity) is expected by this jet formation scenario. The
statistic results on the sample of AGNs are consistent with the predictions of
this scenario. Finally, the possibility that the jet is driven from a
super-Keplerian rotating hot layer located between the corona and the cold disk
is discussed. We find that, in principle, this layer can also produce a
powerful jet with Q_jet\sim L_bol.


title: Chemical Abundances of H II Regions in the Starburst Galaxy NGC 1705

abstract:
  (Shortened version) We report optical spectroscopy of 16 H II regions in NGC
1705 and [O III] 4363 detections for the first time in five H II regions. The
resulting mean oxygen abundance derived directly from measured electron
temperatures is 12+log(O/H) = 8.21 +/- 0.05, which corresponds to [O/H] =
-0.45, or 35% of the solar value. There are no significant spatial
inhomogeneities in [O III] 4363 oxygen abundances from H II regions at a radius
approximately 10 arcsec from the super star cluster. In H II regions where [O
III] 4363 was not measured, oxygen abundances derived with bright-line methods
(accurate only to 0.2 dex) are in agreement with direct values of the oxygen
abundance. Faint narrow He II 4686 emission is found in two H II regions, but
the implied contribution from O^+3 to the total oxygen abundance is only 0.01
dex. Interestingly, the nitrogen-to-oxygen abundance ratio in the ionized H II
gas agrees with the value for the neutral H I, even though the metallicity of
the neutral gas may be a factor of six lower than that of the ionized gas. This
may be indicative of low-metallicity gas in the halo of the galaxy. Extinction
values, A_V, derived from observed Balmer line ratios along lines of sight to H
II regions are in the range between zero and 0.9 mag. With respect to the
metallicity-luminosity and metallicity-gas fraction diagnostics, the measured
oxygen abundance for NGC 1705 is comparable to Local Group dwarf irregulars at
a given luminosity and gas fraction.


title: Propagation and Transmission of Alfven Waves in Rotating Magnetars

abstract:
  We study the propagation and transmission of Alfven waves in the context of
cylindrical geometry. This approximates the polar cap region of aligned pulsar
with strong magnetic fields. Non-propagating region appears in the presence of
rotation. The displacement current further prevents the low frequency modes
from propagating near the stellar surface. The transmission rates to the
exterior through the surface are calculated. The rates increase with the
frequency and the magnetic field strength. The transmission also depends on the
helicity states of the waves, but the difference becomes small in the high
frequency regime. We also point out the possibility of the spin-up by outgoing
wave emission in the low frequency regime, if a certain condition holds.


title: SB9: The Ninth Catalogue of Spectroscopic Binary Orbits

abstract:
  The Ninth Catalogue of Spectroscopic Binary Orbits
(http://sb9.astro.ulb.ac.be) continues the series of compilations of
spectroscopic orbits carried out over the past 35 years by Batten and
collaborators. As of 2004 May 1st, the new Catalogue holds orbits for 2,386
systems. Some essential differences between this catalogue and its predecessors
are outlined and three straightforward applications are presented: (1)
Completeness assessment: period distribution of SB1s and SB2s; (2) Shortest
periods across the H-R diagram; (3) Period-eccentricity relation.


title:
Velocity Dispersion of Dissolving OB Associations Affected by External
  Pressure of Formation Environment

abstract:
  This paper presents a possible way to understand dissolution of OB
associations (or groups). Assuming rapid escape of parental cloud gas from
associations, we show that the shadow of the formation environment for
associations can be partially imprinted on the velocity dispersion at their
dissolution. This conclusion is not surprising as long as associations are
formed in a multiphase interstellar medium, because the external pressure
should suppress expansion caused by the internal motion of the parental clouds.
Our model predicts a few km s$^{-1}$ as the internal velocity dispersion.
Observationally, the internal velocity dispersion is $\sim 1$ km s$^{-1}$ which
is smaller than our prediction. This suggests that the dissipation of internal
energy happens before the formation of OB associations.


title:
A decreasing column density during the prompt emission from GRB000528
  observed with BeppoSAX

abstract:
  We report observation results of the prompt X-- and $\gamma$--ray emission
from GRB 000528. This event was detected with the Gamma-Ray Burst Monitor and
one of the two Wide Field Cameras aboard the BeppoSAX satellite. The GRB was
promptly followed on with the BeppoSAX Narrow Field Instruments and with ground
optical and radio telescopes. The X-ray afterglow source was identified, but no
optical or radio counterpart found. We report here results from the prompt and
afterglow emission analysis. The main feature derived from spectral evolution
of the prompt emission is a high hydrogen-equivalent column density with
evidence of its decrease with time. We model this behavior in terms of a
time-dependent photoionization of the local circum-burst medium, finding that a
compact and dense environment is required by the data. We also find a fading of
the late part of the 2--10 keV prompt emission which is consistent with
afterglow emission. We discuss this result in the light of the external shock
model scenario.


title: A new mass-ratio for the X-ray Binary X2127+119 in M15?

abstract:
  The luminous low-mass X-ray binary X2127+119 in the core of the globular
cluster M15 (NGC 7078), which has an orbital period of 17 hours, has long been
assumed to contain a donor star evolving off the main sequence, with a mass of
0.8 solar masses (the main-sequence turn-off mass for M15). We present
orbital-phase-resolved spectroscopy of X2127+119 in the H-alpha and He I 6678
spectral region, obtained with the Hubble Space Telescope. We show that these
data are incompatible with the assumed masses of X2127+119's component stars.
The continuum eclipse is too shallow, indicating that much of the accretion
disc remains visible during eclipse, and therefore that the size of the donor
star relative to the disc is much smaller in this high-inclination system than
the assumed mass-ratio allows. Furthermore, the flux of X2127+119's He I 6678
emission, which has a velocity that implies an association with the stream-disc
impact region, remains unchanged through eclipse, implying that material from
the impact region is always visible. This should not be possible if the
previously-assumed mass ratio is correct. In addition, we do not detect any
spectral features from the donor star, which is unexpected for a 0.8 solar-mass
sub-giant in a system with a 17-hour period.


title:
Organic molecules in protoplanetary disks around TTauri and HerbigAe
  stars

abstract:
  The results of single-dish observations of low- and high-J transitions of
selected molecules from protoplanetary disks around two TTauri stars (LkCa15
and TWHya) and two HerbigAe stars (HD163296 and MWC480) are reported. Simple
molecules such as CO, 13CO, HCO+, CN and HCN are detected. Several lines of
H2CO are found toward the TTauri star LkCa15 but not in other objects. No CH3OH
has been detected down to abundances of 10E-9 - 10E-8 with respect to H2. SO
and CS lines have been searched for without success. Line ratios indicate that
the molecular emission arises from dense 10E6 - 10E8 cm-3 and moderately warm
(T ~ 20-40K) intermediate height regions of the disk atmosphere, in accordance
with predictions from models of the chemistry in disks. The abundances of most
species are lower than in the envelope around the solar-mass protostar IRAS
16293-2422. Freeze-out and photodissociation are likely causes of the
depletion. DCO+ is detected toward TWHya, but not in other objects. The high
inferred DCO+/HCO+ ratio of ~0.035 is consistent with models of the deuterium
fractionation in disks which include strong depletion of CO. The inferred
ionization fraction in the intermediate height regions as deduced from HCO+ is
at least 10E-11 - 10E-10, comparable to that derived for the midplane from
recent H2D+ observations. (abridged abstract)


title:
A Unified Picture of Disk Galaxies where Bars, Spirals and Warps Result
  from the Same Fundamental Causes

abstract:
  Bars and spiral arms have played an important role as constraints on the
dynamics and on the distribution of dark matter in the optical parts of disk
galaxies. Dynamics linked to the dissipative nature of gas, and its
transformation into stars provide clues that spiral galaxies are driven by
dissipation close to a state of \textit{marginal stability} with respect to the
dynamics in the galaxy plane. Here we present numerical evidences that warps
play a similar role but in the transverse direction. N-body simulations show
that typical galactic disks are also marginally stable with respect to a
bending instability leading to typical observed warps. The frequent occurrence
of warps and asymmetries in the outer galactic disks give therefore, like bars
in the inner disks, new constraints on the dark matter, but this time in the
outer disks. If disks are marginally stable with respect to bending
instabilities, our models suggest that the mass within the HI disks must be a
multiple of the detected HI and stars, i.e., disks must be heavier than seen.
But the models do not rule out a traditional thick halo with a mass within the
HI disk radius similar to the total disk mass.


title: X-Ray Observations of Gamma-Ray Burst Afterglows

abstract:
  The discovery by the BeppoSAX satellite of X-ray afterglow emission from the
gamma-ray burst which occurred on 28 February 1997 produced a revolution in our
knowledge of the gamma-ray burst phenomenon. Along with the discovery of X-ray
afterglows, the optical afterglows of gamma-ray bursts were discovered and the
distance issue was settled, at least for long $\gamma$-ray bursts. The 30 year
mystery of the gamma-ray burst phenomenon is now on the way to solution. Here I
rewiew the observational status of the X-ray afterglow emission, its mean
properties (detection rate, continuum spectra, line features, and light
curves), and the X-ray constraints on theoretical models of gamma-ray bursters
and their progenitors. I also discuss the early onset afterglow emission, the
remaining questions, and the role of future X-ray afterglow observations.


title:
Three new X-ray pulsars detected in the Small Magellanic Cloud and the
  positions of two other known pulsars determined

abstract:
  Three new X-ray pulsars have been detected in the Small Magellanic Cloud
(SMC) and the positions of two others have been determined, with archive
Chandra data. A series of five observations of the SMC took place between May
and October 2002. Analysis of these data has revealed three previously unknown
X-ray pulsars at pulse periods of 34, 503 and 138 seconds. The position of
pulsar XTE J0052-725, which was originally detected by RXTE on June 19 2002,
was also accurately determined and a previously detected 7.78s RXTE pulsar was
identified as the source SMC X-3.


title: The Pleiades mass function: models versus observations

abstract:
  Two stellar-dynamical models of binary-rich embedded proto-Orion-Nebula-type
clusters that evolve to Pleiades-like clusters are studied with an emphasis on
comparing the stellar mass function with observational constraints. By the age
of the Pleiades (about 100 Myr) both models show a similar degree of mass
segregation which also agrees with observational constraints. This thus
indicates that the Pleiades is well relaxed and that it is suffering from
severe amnesia. It is found that the initial mass function (IMF) must have been
indistinguishable from the standard or Galactic-field IMF for stars with mass m
< 2 Mo, provided the Pleiades precursor had a central density of about 10^4.8
stars/pc^3. A denser model with 10^5.8 stars/pc^3 also leads to reasonable
agreement with observational constraints, but owing to the shorter relaxation
time of the embedded cluster it evolves through energy equipartition to a
mass-segregated condition just prior to residual-gas expulsion. This model
consequently looses preferentially low-mass stars and brown dwarfs (BDs), but
the effect is not very pronounced. The empirical data indicate that the
Pleiades IMF may have been steeper than Salpeter for stars with m > 2 Mo.


title: Optical Photometry of SN 1993J: Years 1995 to 2003

abstract:
  In this paper, the late-time optical photometry of supernova (SN) 1993J in
M81 from Feburary 1995 to Janurary 2003 is presented. The observations were
performed in a set of intermediate-band filters that have the advantage of
tracing the strength variations of some spectral features. SN 1993J was found
to fade very slowly at late times, declining only by $0.05\pm0.02$ mag 100
d$^{-1}$ in most of the filters from 2 to nearly 10 yrs after discovery. Our
data suggest that the circumstellar interaction provides most of the energy to
power the late-time optical emission of SN 1993J. This is manifested by several
flux peaks seen in the rough spectral energy distributions constructed from the
multicolor light curves. The flux peaks near 6600 \AA, 5800 \AA{} and 4900
\AA{} may correspond to the emission lines of H$\alpha$, Na I D + He I
$\lambda$5876 and [O III] $\lambda\lambda$4959, 5007, respectively. The
evolution of these emission lines suggest a power-law SN density model as
proposed by \citet{cf94}.


title:
On the Generation of the Hubble Sequence through an Internal Secular
  Dynamical Process

abstract:
  The secular evolution process, which slowly transforms the morphology of a
galaxy over its lifetime, could naturally account for observed properties of
the great majority of physical galaxies if both stellar and gaseous accretion
processes are taken into account. As an emerging paradigm for galaxy evolution,
its dynamical foundation had been established in the past few years, and its
observational consequences are yet to be fully explored. The secular evolution
picture provides a coherent framework for understanding the extraordinary
regularity and the systematic variation of galaxy properties along the Hubble
sequence.


title: C, S, Zn and Cu abundances in planet-harbouring stars

abstract:
  We present a detailed and uniform study of C, S, Zn and Cu abundances in a
large set of planet host stars, as well as in a homogeneous comparison sample
of solar-type dwarfs with no known planetary-mass companions. Carbon abundances
were derived by {EW} measurement of two C I optical lines, while spectral
syntheses were performed for S, Zn and Cu. We investigated possible differences
in the behaviours of the volatiles C, S and Zn and in the refractory Cu in
targets with and without known planets in order to check possible anomalies due
to the presence of planets. We found that the abundance distributions in stars
with exoplanets are the high [Fe/H] extensions of the trends traced by the
comparison sample. All volatile elements we studied show [X/Fe] trends
decreasing with [Fe/H] in the metallicity range -0.8<[Fe/H]<0.5, with
significantly negative slopes of -0.39+-0.04 and -0.35+-0.04 for C and S,
respectively. A comparison of our abundances with those available in the
literature shows good agreement in most cases.


title:
Dark matter haloes: an additional criterion for the choice of fitting
  density profiles

abstract:
  Simulated dark matter haloes are fitted by self-similar, universal density
profiles, where the scaled parameters depend only on a scaled (truncation)
radius which, in turn, is supposed to be independent on the mass and the
formation redshift. A criterion for the choice of the best fitting density
profile is proposed, with regard to a set of high-resolution simulations, where
some averaging procedure on scaled density profiles has been performed, in
connection with a number of fitting density profiles. An application is made to
a pair of sets each made of a dozen of high-resolution simulations, which are
available in literature, in connection with two currently used fitting density
profiles, where the dependence of the scaled radius on the mass and the
formation redshift, may be neglected to a first extent. Some features of the
early evolution of dark matter haloes represented by fitting density profiles,
are discussed in the limit of the spherical top-hat model.


title: The upper kHz QPO: a gravitationally lensed vertical oscillation

abstract:
  We show that a luminous torus in the Schwarzschild metric oscillating along
its own axis gives rise to a periodically varying flux of radiation, even
though the source of radiation is steady and perfectly axisymmetric. This
implies that the simplest oscillation mode in an accretion flow, axisymmetric
up-and-down motion at the meridional epicyclic frequency, may be directly
observable when it occurs in the inner parts of accretion flow around neutron
stars and black holes. The high-frequency modulations of the X-ray flux
observed in low-mass X-ray binaries at two frequencies (twin kHz QPOs) could
then be a signature of strong gravity both because radial and meridional
oscillations have different frequencies in non-Newtonian gravity, and because
strong gravitational deflection of light rays causes the flux of radiation to
be modulated at the higher frequency.


title:
Adaptive Optics Nulling Interferometric Constraints on the Mid-Infrared
  Exozodiacal Dust Emission around Vega

abstract:
  We present the results of mid-infrared nulling interferometric observations
of the main-sequence star alpha Lyr (Vega) using the 6.5 m MMT with its
adaptive secondary mirror. From the observations at 10.6 microns, we find that
there is no resolved emission from the circumstellar environment (at
separations greater than 0.8 AU) above 2.1% (3 sigma limit) of the level of the
stellar photospheric emission. Thus, we are able to place an upper limit on the
density of dust in the inner system of 650 times that of our own solar system's
zodiacal cloud. This limit is roughly 2.8 times better than those determined
with photometric excess observations such as those by IRAS. Comparison with
far-infrared observations by IRAS shows that the density of warm dust in the
inner system (< 30 AU) is significantly lower than cold dust at larger
separations. We consider two scenarios for grain removal, the sublimation of
ice grains and the presence of a planetary mass "sweeper." We find that if
sublimation of ice grains is the only removal process, a large fraction (> 80%)
of the material in the outer system is ice.


title: The Orbit, Mass, and Albedo of Transneptunian Binary 1999 RZ253

abstract:
  We have observed 1999 RZ253 with the Hubble Space Telescope at seven separate
epochs and have fit an orbit to the observed relative positions of this binary.
Two orbital solutions have been identified that differ primarily in the
inclination of the orbit plane. The best fit corresponds to an orbital period,
P=46.263 +0.006/-0.074 days, semimajor axis a=4,660 +/-170 km and orbital
eccentricity e=0.460 +/-0.013 corresponding to a system mass m=3.7 +/-0.4
x10^18 kg. For a density of rho = 1000 kg m^-3 the albedo at 477 nm is p = 0.12
+/-0.01, significantly higher than has been commonly assumed for objects in the
Kuiper Belt. Multicolor, multiepoch photometry shows this pair to have colors
typical for the Kuiper belt with a spectral gradient of 0.35 per 100 nm in the
range between 475 and 775 nm. Photometric variations at the four epochs we
observed were as large as 12 +/-3% but the sampling is insufficient to confirm
the existence of a lightcurve.


title:
The First Measurements of Galaxy Clustering from IRAC Data of the
  Spitzer First Look Survey

abstract:
  We present the first results of the angular auto-correlation function of the
galaxies detected by the Infrared Array Camera (IRAC) instrument in the First
Look Survey (FLS) of the Spitzer Space Telescope. We detect significant signals
of galaxy clustering within the survey area. The angular auto-correlation
function of the galaxies detected in each of the four IRAC instrument channels
is consistent with a power-law form $w(\theta)=A\theta^{1-\gamma}$ out to
$\theta = 0.2\arcdeg$, with the slope ranging from $\gamma = 1.5$ to 1.8. We
estimate the correlation amplitudes $A$ to be $2.95 \times 10^{-3}$, $2.03
\times 10^{-3}$, $4.53 \times 10^{-3}$, and $2.34 \times 10^{-3}$ at
$\theta=1\arcdeg$ for galaxies detected in the IRAC 3.6$\mu$m, 4.5$\mu$m,
5.8$\mu$m, and 8.0$\mu$m instrument channels, respectively. We compare our
measurements at 3.6$\mu$m with the previous K-band measurements, and discuss
the implications of these results.


title: Spectral Types of Field and Cluster O-Stars

abstract:
  The recent catalog of spectral types of Galactic O-type stars by
Mai'z-Apella'niz et al. has been used to study the differences between the
frequencies of various subtypes of O-type stars in the field, in OB
associations and among runaway stars. At a high level of statistical
significance the data show that O-stars in clusters and associations have
earlier types (and hence presumably larger masses and/or younger ages) than
those that are situated in the general field. Furthermore it is found that the
distribution of spectral subtypes among runaway O-stars is indistinguishable
from that among field stars, and differs significantly from that of the O-type
stars that are situated in clusters and associations. The difference is in the
sense that runaway O-stars, on average, have later subtypes than do those that
are still located in clusters and associations.


title:
The Great Observatories Origins Deep Survey - VLT/FORS2 Spectroscopy in
  the GOODS-South Field

abstract:
  We present the first results of the ESO/GOODS program of spectroscopy of
faint galaxies in the Chandra Deep Field South (CDF-S). 399 spectra of 303
unique targets have been obtained in service mode with the FORS2 spectrograph
at the ESO/VLT, providing 234 redshift determinations (the median of the
redshift distribution is at 1.04). The typical redshift uncertainty is
estimated to be sig(z) ~ 0.001. Galaxies have been color selected in a way that
the resulting redshift distribution typically spans from z=0.5 to 2. The
reduced spectra and the derived redshifts are released to the community through
the ESO web page http://www.eso.org/science/goods/ Large scale structure is
clearly detected at z ~ 0.67, 0.73, 1.10 and 1.61. Three Lyman-break galaxies
have also been included as targets and are confirmed to have redshifts z=4.800,
4.882 and 5.828. In a few cases, we observe clear [OII]3727 rotation curves,
even at the relatively low resolution (R = 860) of the present observations.
Assuming that the observed velocity structure is due to dynamically-relaxed
rotation, this is an indication of large galactic masses (few times 10^(11)
solar masses) at z ~ 1.


title:
Ain't No Crab, PWN Got A Brand New Bag: Correlated radio and X-ray
  Structures in Pulsar Wind Nebulae

abstract:
  The traditional view of radio pulsar wind nebulae (PWN), encouraged by the
Crab nebula's X-ray and radio morphologies, is that they are a result of the
integrated history of their pulsars' wind. The radio emission should therefore
be largely unaffected by recent pulsar activity, and hence minimally correlated
with structures in the X-ray nebulae. Observations of several PWN, both
stationary (sPWN) and rapidly moving (rPWN), now show clear morphological
relationships between structures in the radio and X-ray with radio intensity
variations on the order of unity. We present high-resolution X-ray and radio
images of several PWN of both types and discuss the morphological relationships
between the two wavebands.


title:
The Two-Point Correlation of Galaxy Groups: Probing the Clustering of
  Dark Matter Haloes

abstract:
  We analyze the 2-point correlation function (2PCF) of galaxy groups
identified from the 2-degree Field Galaxy Redshift Survey with the halo based
group finder recently developed by Yang et al (2004b). With this group
catalogue we are able to estimate the 2PCFs for systems ranging from isolated
galaxies to rich clusters of galaxies. The real-space correlation length
obtained for these systems ranges from $\sim 4\mpch$ to $\sim 15\mpch$,
respectively. The observed correlation amplitude (and the corresponding bias
factor) as a function of group abundance is well reproduced by associating
galaxy groups with dark matter haloes in the standard $\Lambda$CDM model.
Redshift distortions are clearly detected in the redshift-space correlation
function, the degree of which is consistent with the assumption of
gravitational clustering and halo bias in the cosmic density field. In
agreement with previous studies we find a strong increase of the correlation
length with the mean inter-group separation. Although well determined
observationally, we show that current theoretical predictions are not yet
accurate enough to allow for stringent constraints on cosmological parameters.
Finally, we use our results to explore the power-law nature of the 2PCF of
galaxies. We split the 2PCF in 1-group and 2-group terms, equivalent to the
1-halo and 2-halo terms in halo occupation models, and show that the power-law
form of the 2PCF is broken, when only including galaxies in the more massive
systems.


title:
SDSS galaxy bias from halo mass-bias relation and its cosmological
  implications

abstract:
  We combine the measurements of luminosity dependence of bias with the
luminosity dependent weak lensing analysis of dark matter around galaxies to
derive the galaxy bias and constrain nonlinear mass and cosmological
parameters. We take advantage of theoretical and simulation predictions that
predict that while halo bias is rapidly increasing with mass for high masses,
it is nearly constant in low mass halos. We use a new weak lensing analysis
around the same SDSS galaxies to determine their halo mass probability
distribution. These halo mass probability distributions are used to predict the
bias for each luminosity subsample and we find an excellent agreement with
observed values. The required nonlinear mass suggests slightly lower matter
density than usually assumed, Omegam=0.25+/- 0.03 for the simplest models. We
combine the bias constraints with those from the WMAP and the SDSS power
spectrum analysis to derive new constraints on bias and sigma_8. For the most
general parameter space we find sigma_8=0.88+/- 0.06 and b_*=0.99+/- 0.07. In
the context of spatially flat models we improve the limit on the neutrino mass
for the case of 3 degenerate families from m_nu<0.6eV without bias to
m_nu<0.18eV with bias (95% c.l.), which is weakened to m_nu<0.24eV if running
is allowed. The corresponding limit for 3 massless + 1 massive neutrino is
1.37eV.


title: The Anisotropy of Electron MHD Turbulence

abstract:
  We present numerical studies of 3-dimensional electron magnetohydrodynamic
(EMHD) turbulence. We investigate cascade timescale and anisotropy of freely
decaying strong EMHD turbulence with zero electron skin depth. Cascade time
scales with $k^{-4/3}$. Our numerical results clearly show scale-dependent
anisotropy. We discuss that the observed anisotropy is consistent with $k_{\|}
\propto k_{\perp}^{1/3}$, where $k_{\|}$ and $k_{\perp}$ are wave numbers
parallel and perpendicular to (local) mean magnetic field, respectively.


title: A population of hot, dusty ultra-luminous galaxies at z~2

abstract:
  We report spectroscopic redshifts for 18 microJy-radio galaxies at mean
redshift of z=2.2 that are faint at both submmillimeter (submm) and optical
wavelengths. While the radio fluxes of these galaxies could indicate
far-infrared (far-IR) luminosities comparable to high-redshift
submillimeter-selected galaxies (>10^12 Lsun), none are detected in the submm.
We propose that this new population of galaxies represents an extension of the
high-redshift submm galaxy population, but with hotter characteristic dust
temperatures that shift the peak of their far-IR emission to shorter
wavelengths, reducing the submm flux below the sensitivity of current
instruments. Therefore, surveys in the submm waveband may miss up to half of
the most luminous, dusty galaxies at z~2. Mid-infrared observations with
Spitzer will be a powerful tool to test this hypothesis.


title:
Milliarcsec-scale radio structure of a matched sample of Seyfert 1 and
  Seyfert 2 galaxies

abstract:
  We have obtained mas-scale resolution very long baseline interferometry
(VLBI) images of a sample of Seyfert 1 and Seyfert 2 galaxies at 5 GHz
(wavelength, $\lambda$ = 6 cm). The Seyferts of the two types were chosen to be
matched in several orientation-independent properties, primarily in order to
rigorously test predictions of the unified scheme. We detected all the 15
objects that we observed. In this paper we describe the observations and data
reduction procedures, and present the VLBI radio images as well as simultaneous
Very Large Array images that we obtained for these 15 Seyferts.


title: The Origin of Helicity in Solar Active Regions

abstract:
  We present calculations of helicity based on our solar dynamo model and show
that the results are consistent with observational data.


title: Model Atmospheres for Irradiated Stars in pre-Cataclysmic Variables

abstract:
  Model atmospheres have been computed for M dwarfs that are strongly
irradiated by nearby hot companions. A variety of primary and secondary
spectral types are explored in addition to models specific to four known
systems: GD 245, NN Ser, AA Dor, and UU Sge. This work demonstrates that a
dramatic temperature inversion is possible on at least one hemisphere of an
irradiated M dwarf and the emergent spectrum will be significantly different
from an isolated M dwarf or a black body flux distribution. For the first time,
synthetic spectra suitable for direct comparison to high-resolution
observations of irradiated M dwarfs in non-mass transferring post-common
envelope binaries are presented. The effects of departures from local
thermodynamic equilibrium on the Balmer line profiles are also discussed.


title:
Universal Non-Gaussian Velocity Distribution in Violent Gravitational
  Processes

abstract:
  We study the velocity distribution in spherical collapses and cluster-pair
collisions by use of N-body simulations. Reflecting the violent gravitational
processes, the velocity distribution of the resultant quasi-stationary state
generally becomes non-Gaussian. Through the strong mixing of the violent
process, there appears a universal non-Gaussian velocity distribution, which is
a democratic (equal-weighted) superposition of many Gaussian distributions (DT
distribution). This is deeply related with the local virial equilibrium and the
linear mass-temperature relation which characterize the system. We show the
robustness of this distribution function against various initial conditions
which leads to the violent gravitational process. The DT distribution has a
positive correlation with the energy fluctuation of the system. On the other
hand, the coherent motion such as the radial motion in the spherical collapse
and the rotation with the angular momentum suppress the appearance of the DT
distribution.


title:
The Frequency Evolution of Interstellar Pulse Broadening from Radio
  Pulsars

abstract:
  In this paper we report multi-frequency measurements of pulse broadening
times (tau_d) for nine medium dispersion measure (DM $\approx 150-400$ pc
cm$^{-3}$) pulsars observed over a wide frequency range. The low frequency data
at 243, 325 and 610 MHz are new observations done with the Giant Metrewave
Radio Telescope (GMRT). The frequency dependence of tau_d for all but one (PSR
B1933+16) of our sources is consistent with the Kolmogorov spectrum of electron
density fluctuations in a turbulent medium. PSR B1933+16, however, shows a very
flat spectrum as previously observed for high DM pulsars. Our observations
combined with earlier published results enable us to study the spectral index
of tau_d over the whole observed DM range. While the spectral properties are
generally consistent with a Kolmogorov spectrum, pulsars seen along
line-of-sights towards the inner Galaxy or complex regions often show
deviations from this expected behaviour.


title: A Search for Cold Dust around Neutron Stars

abstract:
  We present observations of nine radio pulsars using the
Heinrich-Hertz-Telescope at \lambda 0.87mm and the IRAM 30-m telescope at
\lambda 1.2mm in search for a cold dust around these sources. Five of the
program pulsars have been observed for the first time at the mm-wavelengths.
The results are consistent with the absence of circumpulsar disks that would be
massive enough ($\ge 0.01 M_{\odot}$) to support planet formation according to
the scenarios envisioned for solar-type stars, but they do not exclude lower
mass ($\le 10-100 M_{\oplus}$) disks for a wide range of grain sizes. These
conclusions confirm the previously published results and, together with the
current lack of further detections of pulsar planets, they suggest that planet
formation around neutron stars is not a common phenomenon.


title: Self-similar imploding relativistic shock waves

abstract:
  Self-similar solutions to the problem of a strong imploding relativistic
shock wave are calculated. These solutions represent the relativistic
generalisation of the Newtonian Gouderley-Landau-Stanyukovich problem of a
strong imploding spherical shock wave converging to a centre. The solutions are
found assuming that the pre-shocked flow has a uniform density, and are
accurate for sufficiently large times after the formation of the shock wave.


title:
A high-significance detection of non-Gaussianity in the WMAP 1-year data
  using directional spherical wavelets

abstract:
  A directional spherical wavelet analysis is performed to examine the
Gaussianity of the WMAP 1-year data. Such an analysis is facilitated by the
introduction of a fast directional continuous spherical wavelet transform. The
directional nature of the analysis allows one to probe orientated structure in
the data. Significant deviations from Gaussianity are detected in the skewness
and kurtosis of spherical elliptical Mexican hat and real Morlet wavelet
coefficients for both the WMAP and Tegmark et al. (2003) foreground-removed
maps. The previous non-Gaussianity detection made by Vielva et al. (2003) using
the spherical symmetric Mexican hat wavelet is confirmed, although their
detection at the 99.9% significance level is only made at the 95.3%
significance level using our most conservative statistical test. Furthermore,
deviations from Gaussianity in the skewness of spherical real Morlet wavelet
coefficients on a wavelet scale of 550 arcmin (corresponding to an effective
global size on the sky of approximately 26 degrees and an internal size of 3
degrees) at an azimuthal orientation of 72 degrees, are made at the 98.3%
significance level, using the same conservative method. The wavelet analysis
inherently allows one to localise on the sky those regions that introduce
skewness and those that introduce kurtosis. Preliminary noise analysis
indicates that these detected deviation regions are not atypical and have
average noise dispersion. Further analysis is required to ascertain whether
these detected regions correspond to secondary or instrumental effects, or
whether in fact the non-Gaussianity detected is due to intrinsic primordial
fluctuations in the cosmic microwave background.


title: 3C 129 : The GMRT observations

abstract:
  We present radio maps of the head-tail radio galaxy, 3C 129 at 240 and 610
MHz using the Giant Metrewave Radio Telescope. We have studied in detail the
morphology of the source and the distribution of spectral index over the
object. We find large-scale spectral steepening along the jet away from the
core. Using synchrotron spectral ageing theory, we infer the age (time since
particle acceleration) of electrons at various locations along the jet and
ascribe an age of $\sim$200 Myr to 3C 129. We find that the "Crosspiece" has a
spectral index of ${\sim}-1$, similar to the jet, which is not consistent with
the suggestion by Lane et al. (2002) that it could be a radio relic. We have
also studied 3C 129.1 and the other sources in the field.


title: Stochastic Gravitational Wave Background in Brane World Cosmology

abstract:
  We investigate the cosmological evolution of gravitational waves in
Friedman-Robertson-Walker brane world models embedded in a five dimensional
anti de-Sitter spacetime. To predict the spectrum of stochastic gravitational
background at present generated in the inflationary phase, we numerically
calculate the evolution of gravitational waves according to the method
developed in our previous paper [K. Ichiki and K. Nakamura,
arXiv:hep-th/0310282]. The resulting logarithmic energy spectrum is
significantly altered from that of the standard four dimensional inflationary
models in the frequency range f > f_{AdS} ~ 10^{-4} Hz, which corresponds to
the curvature scale we set of anti de-Sitter spacetime, $l ~ 1$mm.


title: Disk Outflows and the Accretion Rate Gap

abstract:
  We argue that the observed `accretion rate gap' - between black holes in
radio-loud active galactic nuclei (AGN) accreting at close to the Eddington
limit and those accreting at considerably lower rates - can be explained in
terms of the adiabatic inflow-outflow (ADIOS) scenario for radiatively
inefficient accretion. Whenever the accretion rate falls below a threshold
value (corresponding to a luminosity L_crit) that depends on the viscosity
parameter, alpha, the inner region of the accretion disk - extending from the
marginally stable orbit to ~ 1000 Schwarzschild radii - is susceptible to
becoming hot and radiatively inefficient. If this happens, the disk luminosity
decreases by a factor of ~100, as most of the matter originally destined to be
swallowed is instead expelled in a wind. According to our conjecture, accretion
flows onto black holes never radiate steadily in the range ~ 0.01 L_crit < L <
L_crit, hence the inferred accretion rate gap. We expect the gap to exist also
for black holes in X-ray binaries, where it may be responsible for state
transitions and the luminosity fluctuations associated with X-ray nova
outbursts.


title:
The foundations of observing dark energy dynamics with the Wilkinson
  Microwave Anisotropy Probe

abstract:
  Detecting dark energy dynamics is the main quest of current dark energy
research. Addressing the issue demands a fully consistent analysis of CMB,
large scale structure and SN-Ia data with multi-parameter freedom valid for all
redshifts. Here we undertake a ten parameter analysis of general dark energy
confronted with the first year WMAP, 2dF galaxy survey and latest SN-Ia data.
Despite the huge freedom in dark energy dynamics there are no new degeneracies
with standard cosmic parameters apart from a mild degeneracy between
reionisation and the redshift of acceleration, both of which effectively
suppress small scale power. Breaking this degeneracy will help significantly in
detecting dynamics, if it exists. Our best-fit model to the data has
significant late-time evolution at z<1.5. Phantom models are also considered
and we find that the best-fit crosses w=-1 which, if confirmed, would be a
clear signal for radically new physics. Treatment of such rapidly varying
models requires careful integration of the dark energy density usually not
implemented in standard codes, leading to crucial errors of up to 5%.
Nevertheless cosmic variance means that standard LCDM models are still a very
good fit to the data and evidence for dynamics is currently very weak.
Independent tests of reionisation or the epoch of acceleration (e.g. ISW-LSS
correlations) or reduction of cosmic variance at large scales (e.g. cluster
polarisation at high redshift) may prove key in the hunt for dynamics.


title:
A model for the flaring radio emission in the double pulsar system
  J0737-3039

abstract:
  The binary J0737-3039 A & B includes two pulsars in a highly relativistic
orbit. The pulsed radio flux from pulsar B brightens considerably during two
portions of each orbit. This phenomenon cannot be naturally triggered by the
illumination of $\gamma$-rays or X-rays from pulsar A or the bow shock around
pulsar B. Instead, we explain these periodic flares quantitatively as episodes
during which pairs from pulsar A's wind flow into the open field line region of
pulsar B and emit curvature radiation at radio frequencies within an altitude
of $\sim 10^8$ cm. The radio photons then travel through B's magnetosphere and
eventually reach the observer on the other side of the pulsar. Our model
requires that A's wind be anisotropic and that B's spin axis be somewhat
misaligned relative to the orbital angular momentum. We estimate the expected
$\gamma$-ray and X-ray emission from the system.


title: Night sky brightness at sites from DMSP-OLS satellite measurements

abstract:
  We apply the sky brightness modelling technique introduced and developed by
Roy Garstang to high-resolution DMSP-OLS satellite measurements of upward
artificial light flux and to GTOPO30 digital elevation data in order to predict
the brightness distribution of the night sky at a given site in the primary
astronomical photometric bands for a range of atmospheric aerosol contents.
This method, based on global data and accounting for elevation, Earth curvature
and mountain screening, allows the evaluation of sky glow conditions over the
entire sky for any site in the World, to evaluate its evolution, to disentangle
the contribution of individual sources in the surrounding territory, and to
identify main contributing sources. Sky brightness, naked eye stellar
visibility and telescope limiting magnitude are produced as 3-dimensional
arrays whose axes are the position on the sky and the atmospheric clarity. We
compared our results to available measurements.


title: Seyfert galaxies: Nuclear Radio Structure and Unification

abstract:
  We have observed a sample of Seyfert (Sy) galaxies with the global Very Long
Baseline Interferometry (VLBI) to test the predictions of the unification
scheme for the Sy galaxies which hypothesises that Sys of Type 1 and of Type 2
constitute a single population of objects. If Sy 1 and Sy 2 galaxies differ
only in the orientation of the axisymmmetric active nucleus with respect to the
observer, then, the parsec scale radio structures of the two types should be
similar.
  The overall goal of the thesis is to rigorously test the predictions of the
unified scheme hypothesis for the Sy galaxies.
  We chose a sample of 10 Sy 1s and 10 Sy 2s such that the two subsamples were
intrinsically similar within the framework of the unified scheme. This was done
by matching them as far as possible in the orientation-independent parameters
{\it viz.}, host galaxy properties and measures of intrinsic Active Galactic
Nuclei (AGN) power.
  We here present the results obtained from these observations and their
implications on the unification scheme. We also discuss the results obtained
from the measurements at all IRAS and 2-10 keV X-ray wavebands for our Sy
galaxy sample using data from the literature.


title: The [Zn/Fe] -- [Fe/H] trend for disk and halo stars

abstract:
  Zn abundances, derived from a model atmosphere analysis of the 6362.35 A ZnI
line, are presented for 44 thin disk, 10 thick disk and 8 halo dwarf stars in
the metallicity range -1.0 [Fe/H] +0.2. It is found that [Zn/Fe] in thin disk
stars shows a slight increasing trend with decreasing metallicity reaching a
value [Zn/Fe] ~ +0.1 at [Fe/H] = -0.6. The thick disk stars in the metallicity
range -0.9 < [Fe/H] < -0.6 have an average [Zn/Fe] ~ +0.15 dex, whereas five
alpha-poor and Ni-poor halo stars in the same metallicity range have [Zn/Fe] ~
0.0 dex. These results indicate that Zn is not an exact tracer of Fe as often
assumed in abundance studies of damped Lyman-alpha systems (DLAs). A better
understanding of the nucleosynthesis of Zn is needed in order to obtain more
detailed information on the past history of star formation in DLAs from e.g.
the observed sulphur/zinc ratio.


title:
Ultra Compact Dwarf galaxies in Abell 1689: a photometric study with the
  ACS

abstract:
  The properties of Ultra Compact Dwarf (UCD) galaxy candidates in Abell 1689
(z=0.183) are investigated, based on deep high resolution ACS images. A UCD
candidate has to be unresolved, have i<28 (M_V<-11.5) mag and satisfy color
limits derived from Bayesian photometric redshifts. We find 160 UCD candidates
with 22<i<28 mag. It is estimated that about 100 of these are cluster members,
based on their spatial distribution and photometric redshifts. For i>26.8 mag,
the radial and luminosity distribution of the UCD candidates can be explained
well by Abell 1689's globular cluster (GC) system. For i<26.8 mag, there is an
overpopulation of 15 +/- 5 UCD candidates with respect to the GC luminosity
function. For i<26 mag, the radial distribution of UCD candidates is more
consistent with the dwarf galaxy population than with the GC system of Abell
1689. The UCD candidates follow a color-magnitude trend with a slope similar to
that of Abell 1689's genuine dwarf galaxy population, but shifted fainter by
about 2-3 mag. Two of the three brightest UCD candidates (M_V ~ -17 mag) are
slightly resolved. At the distance of Abell 1689, these two objects would have
King-profile core radii of ~35 pc and r_eff ~300 pc, implying luminosities and
sizes 2-3 times those of M32's bulge. Additional photometric redshifts obtained
with late type stellar and elliptical galaxy templates support the assignment
of these two resolved sources to Abell 1689. Our findings imply that in Abell
1689 there are at least 10 UCDs with M_V<-12.7 mag. Compared to the UCDs in the
Fornax cluster they are brighter, larger and have colors closer to normal dwarf
galaxies. This suggests that they may be in an intermediate stage of the
stripping process. Spectroscopy is needed to definitely confirm the existence
of UCDs in Abell 1689.


title: Primary Proton Spectrum of Cosmic Rays measured with Single Hadrons

abstract:
  The flux of cosmic-ray induced single hadrons near sea level has been
measured with the large hadron calorimeter of the KASCADE experiment. The
measurement corroborates former results obtained with detectors of smaller size
if the enlarged veto of the 304 m^2 calorimeter surface is encounted for. The
program CORSIKA/QGSJET is used to compute the cosmic-ray flux above the
atmosphere. Between E_0=300 GeV and 1 PeV the primary proton spectrum can be
described with a power law parametrized as
dJ/dE_0=(0.15+-0.03)*E_0^{-2.78+-0.03} m^-2 s^-1 sr^-1 TeV^-1. In the TeV
region the proton flux compares well with the results from recent measurements
of direct experiments.


title: On the age-radius relation and orbital history of cluster galaxies

abstract:
  We explore the region of influence of a galaxy cluster using numerical
simulations of cold dark matter halos. Many of the observed galaxies in a
cluster are expected to be infalling for the first time. Half of the halos at
distances of one to two virial radii today have previously orbited through the
cluster, most of them have even passed through the dense inner regions of the
cluster. Some halos at distances of up to three times the virial radius have
also passed through the cluster core. We do not find a significant correlation
of ``infall age'' versus present day position for substructures and the scatter
at a given position is very large. This relation may be much more significant
if we could resolve the physically overmerged galaxies in the central region.


title:
The cosmic background: evolution of infrared galaxies and dust
  properties. A lecture dedicated to the memory of Mayo Greenberg

abstract:
  In recent years it became clear that a population of galaxies radiating most
of their power in the far-infrared contribute an important part of the whole
star formation activity in the universe. These galaxies emit up to 99% of their
energy output in the infrared by dust. The optical properties of dust in
galaxies are thus very important to understand this population. Mayo Greenberg
who has brought many of the ideas underlying our understanding of the physics
of interstellar dust has been a pioneer in predicting the important role of
organic solid material formed on dust grains in molecular clouds and of
potential importance of transient heating of very small particles. It appeared
with the ISO data on galaxies and even more today with the first Spitzer data
that these mechanisms are important globally for the observations of infrared
galaxies at significant redshifts. The understanding of their evolution is one
of the keys to the understanding of galaxy built up and evolution.


title: A cloudy Vlasov solution

abstract:
  We propose to integrate the Vlasov-Poisson equations giving the evolution of
a dynamical system in phase-space using a continuous set of local basis
functions. In practice, the method decomposes the density in phase-space into
small smooth units having compact support. We call these small units ``clouds''
and choose them to be Gaussians of elliptical support. Fortunately, the
evolution of these clouds in the local potential has an analytical solution,
that can be used to evolve the whole system during a significant fraction of
dynamical time. In the process, the clouds, initially round, change shape and
get elongated. At some point, the system needs to be remapped on round clouds
once again. This remapping can be performed optimally using a small number of
Lucy iterations. The remapped solution can be evolved again with the cloud
method, and the process can be iterated a large number of times without showing
significant diffusion. Our numerical experiments show that it is possible to
follow the 2 dimensional phase space distribution during a large number of
dynamical times with excellent accuracy. The main limitation to this accuracy
is the finite size of the clouds, which results in coarse graining the
structures smaller than the clouds and induces small aliasing effects at these
scales. However, it is shown in this paper that this method is consistent with
an adaptive refinement algorithm which allows one to track the evolution of the
finer structure in phase space. It is also shown that the generalization of the
cloud method to the 4 dimensional and the 6 dimensional phase space is quite
natural.


title: V1647 Ori (IRAS 05436-0007) in Outburst: the First Three Months

abstract:
  We report on photometric (BVRIJHK) and low dispersion spectroscopic
observations of V1647 Ori, the star that drives McNeil's Nebula, between 10
February and 7 May 2004. The star is photometrically variable atop a general
decline in brightness of about 0.3-0.4 magnitudes during these 87 days. The
spectra are featureless, aside from H-alpha and the Ca II infrared triplet in
emission, and a Na I D absorption feature. The Ca II triplet line ratios are
typical of young stellar objects. The H-alpha equivalent width may be modulated
on a period of about 60 days. The post-outburst extinction appears to be less
than 7 mag. The data are suggestive of an FU Orionis-like event, but further
monitoring will be needed to definitively characterize the outburst.


title: Non-thermal Mg I emission at 12 um from Procyon

abstract:
  We report on stellar Mg I emission at 12 um from alpha CMi (Procyon), a star
slightly hotter than the Sun. Solar Mg I emission is well-known and its
formation was successfully explained in detail by Carlsson et al. (1992). Here,
for the first time, we compare synthetic spectra of the emission lines at 12 um
with observations of a star other than the Sun. The use of these lines as
stellar diagnostics has been anticipated for 10 years or more. We find that the
model reproduces the observed emission in Procyon quite well. We expect that
high-resolution spectrographs on 8-10 m telescopes will finally be able to
exploit these new diagnostics.