title: Structural stability of cooling flows

abstract:
  Three-dimensional hydrodynamical simulations are used to investigate the
structural stability of cooling flows that are episodically heated by jets from
a central AGN. The radial profile of energy deposition is controlled by (a) the
power of the jets, and (b) the pre-outburst density profile. A delay in the
ignition of the jets causes more powerful jets to impact on a more centrally
concentrated medium. The net effect is a sufficient increase in the central
concentration of energy deposition to cause the post-outburst density profile
to be less centrally concentrated than that of an identical cluster in which
the outburst happened earlier and was weaker. These results suggest that the
density profiles of cooling flows oscillate around an attracting profile, thus
explaining why cooling flows are observed to have similar density profiles. The
possibility is raised that powerful FR II systems are ones in which this
feedback mechanism has broken down and a runaway growth of the source
parameters has occurred.


title: CMB Observational Techniques and Recent Results

abstract:
  The Cosmic Microwave Background (CMB) consists of photons that were last
created about 2 months after the Big Bang, and last scattered about 380,000
years after the Big Bang. The spectrum of the CMB is very close to a blackbody
at 2.725 K and upper limits on any deviations of the CMB from a blackbody place
strong constraints on energy transfer between the CMB and matter at all
redshifts less than 2,000,000. The CMB is very nearly isotropic, but a dipole
anisotropy of +/-3.346(17) mK shows that the Solar System barycenter is moving
at 368+/-2 km/sec relative to the observable Universe. The dipole corresponds
to a spherical harmonic index l=1. The higher indices l geq 2 indicate
intrinsic inhomogeneities in the Universe that existed at the time of last
scattering. While the photons have traveled freely only since the time of last
scattering, the inhomogeneities traced by the CMB photons have been in place
since the inflationary epoch only 10^{-35} sec after the Big Bang. These
intrinsic anisotropies are much smaller in amplitude than the dipole
anisotropy, with Delta T leq 100 microK. Electron scattering of the anisotropic
radiation field produces an anisotropic linear polarization in the CMB with
amplitudes less than 5 microK. Detailed studies of the angular power spectrum
of the temperature and linear polarization anisotropies have yielded precise
values for many cosmological parameters. This paper will discuss the techniques
necessary to measure signals that are 100 million times smaller than the
emission from the instrument and briefly describe results from experiments up
to WMAP.


title: Extragalactic Integral Field Spectroscopy on the Gemini Telescopes

abstract:
  We have been undertaking a programme on the Gemini 8-m telescopes to
demonstrate the power of integral field spectroscopy, using the optical GMOS
spectrograph, and the new CIRPASS instrument in the near-infrared. Here we
present some preliminary results from 3D spectroscopy of extra-galactic
objects, mapping the emission lines in a 3CR radio galaxy and in a
gravitationally lensed arc, exploring dark matter sub-structure through
observations of an Einstein Cross gravitational lens, and the star formation
time-scales of young massive clusters in the starburst galaxy NGC 1140.


title:
A simple model for the evolution of super-massive black holes and the
  quasar population

abstract:
  An empirically motivated model is presented for accretion-dominated growth of
the super massive black holes (SMBH) in galaxies, and the implications are
studied for the evolution of the quasar population in the universe. We
investigate the core aspects of the quasar population, including space density
evolution, evolution of the characteristic luminosity, plausible minimum masses
of quasars, the mass function of SMBH and their formation epoch distribution.
Our model suggests that the characteristic luminosity in the quasar luminosity
function arises primarily as a consequence of a characteristic mass scale above
which there is a systematic separation between the black hole and the halo
merging rates. At lower mass scales, black hole merging closely tracks the
merging of dark halos. When combined with a declining efficiency of black hole
formation with redshift, the model can reproduce the quasar luminosity function
over a wide range of redshifts. The observed space density evolution of quasars
is well described by formation rates of SMBH above $\sim 10^8 M_\odot$. The
inferred mass density of SMBH agrees with that found independently from
estimates of the SMBH mass function derived empirically from the quasar
luminosity function.


title:
Stellar Collisions During Binary-Binary and Binary-Single Star
  Interactions

abstract:
  Physical collisions between stars occur frequently in dense star clusters,
either via close encounters between two single stars, or during strong
dynamical interactions involving binary stars. Here we study stellar collisions
that occur during binary-single and binary-binary interactions, by performing
numerical scattering experiments. Our results include cross sections, branching
ratios, and sample distributions of parameters for various outcomes. For
interactions of hard binaries containing main-sequence stars, we find that the
normalized cross section for at least one collision to occur (between any two
of the four stars involved) is essentially unity, and that the probability of
collisions involving more than two stars is significant. Hydrodynamic
calculations have shown that the effective radius of a collision product can be
2-30 times larger than the normal main-sequence radius for a star of the same
total mass. We study the effect of this expansion, and find that it increases
the probability of further collisions considerably. We discuss these results in
the context of recent observations of blue stragglers in globular clusters with
masses exceeding twice the main-sequence turnoff mass. We also present Fewbody,
a new, freely available numerical toolkit for simulating small-N gravitational
dynamics that is particularly suited to performing scattering experiments.


title: Tolman-Bayin type static charged fluid spheres in general relativity

abstract:
  In a static spherically symmetric Einstein-Maxwell spacetime the class of
astrophysical solution found out by Ray and Das (2002) and Pant and Sah (1979)
are revisited here in connection to the phenomenological relationship between
the gravitational and electromagnetic fields. It is qualitatively shown that
the charged relativistic stars of Tolman (1939) and Bayin (1978) type are of
purely electromagnetic origin. The existence of this type of astrophysical
solutions is a probable extension of Lorentz's conjecture that electron-like
extended charged particle possesses only `electromagnetic mass' and no
`material mass'.


title: A Dor - An Eclipsing Subdwarf - Brown Dwarf Binary

abstract:
  AA Dor is an eclipsing, close, post common-envelope binary (PCEB) consisting
of a sdOB primary star and an unseen cool companion with an extraordinary low
mass.
  The evolution of this system appears enigmatic - results of a recent spectral
analysis of the primary has shown that the secondary is formally a brown dwarf.
  We present results of a spectral analysis which is based on phase-resolved
high-resolution and high-SN spectroscopy.


title:
The double radio source 3C343.1: A galaxy-QSO pair with very different
  redshifts

abstract:
  The strong radio source 3C343.1 consists of a galaxy and a QSO separated by
no more than about 0.25 arcsec. The chance of this being an accidental
superposition is conservatively 10^-8. The z=0.344 galaxy is connected to the
z=0.750 QSO by a radio bridge. The numerical relation between the two redshifts
is that predicted from previous associations. This pair is an extreme example
of many similar physical associations of QSOs and galaxies with very different
redshifts.


title: Updated Big-Bang Nucleosynthesis compared to WMAP results

abstract:
  From the observations of the anisotropies of the Cosmic Microwave Background
(CMB) radiation, the WMAP satellite has provided a determination of the
baryonic density of the Universe, \Omega_b.h^2, with an unprecedented
precision. This imposes a careful reanalysis of the standard Big-Bang
Nucleosynthesis (SBBN) calculations. We have updated our previous calculations
using thermonuclear reaction rates provided by a new analysis of experimental
nuclear data constrained by $R$-matrix theory. Combining these BBN results with
the \Omega_b.h^2 value from WMAP, we deduce the light element (4He, D, 3He and
7Li) primordial abundances and compare them with spectroscopic observations.
There is a very good agreement with deuterium observed in cosmological clouds,
which strengthens the confidence on the estimated baryonic density of the
Universe. However, there is an important discrepancy between the deduced 7Li
abundance and the one observed in halo stars of our Galaxy, supposed, until
now, to represent the primordial abundance of this isotope. The origin of this
discrepancy, observational, nuclear or more fundamental remains to be
clarified. The possible role of the up to now neglected 7Be(d,p)2\alpha and
7Be(d,\alpha)5Li reactions is considered.


title:
Chemical abundances of $\beta$ Cephei stars from low- and
  high-resolution UV spectra

abstract:
  In early type stars the ultraviolet spectral region is important for several
reasons. Firstly, since the majority of the total flux is emitted here, it
provides a rather sensitive indicator of a photospheric temperature and
luminosity. Secondly, the UV spectra are dominated by lines of the iron-group
elements, which cause the origin of the opacity bump at temperature $2 \times
10^5$ K, where the classical $\kappa$ mechanism drives pulsations of $\beta$
Cep stars. Consequently, the position of the instability domain in the HR
diagram strongly depends on the metal abundance (Pamyatnykh 1999).
  We derive stellar parameters (metallicity, [m/H], effective temperature,
$T_{\rm eff}$, stellar diameter, $\theta$) and interstellar extinction,
$E(B-V)$, for all $\beta$ Cep stars observed by {\it International Ultraviolet
Explorer} satellite. The parameters are derived by means of an algorithmic
procedure of fitting theoretical flux distributions to the low-resolution IUE
spectra and optical spectrophotometric observations. The errors are estimated
by using the bootstrap method (Press et al. 1992). We also show some examples
of high-resolution HST/GHRS spectra for one $\beta$ Cep star: $\gamma$ Peg.


title: Formation of Super-massive Black Holes

abstract:
  We show that the rapid formation of super-massive black holes in quasars can
indeed be understood in terms of major galaxy mergers followed by disk
accretion. The necessary short disk evolution time can be achieved provided the
disk viscosity is sufficiently large, which, for instance, is the case for
hydrodynamic turbulence, unlimited by shock dissipation. We present numerical
calculations for a representative case. This general picture can account for
(a) the presence of highly luminous quasars at redshifts z > 6; (b) for the
peak in quasar activity at z ~ 2; and (c) for a subsequent rapid disappearance
of quasars at later epochs.


title: Disk-Planet Interaction: Triggered Formation and Migration

abstract:
  We present three-dimensional SPH calculations of giant planets embedded in
gaseous disks. Our findings are collected into a map of parameter space,
exhibiting four distinct regions: Type I migration, gap formation, triggered
formation of more planets, and wholly unstable disks. For Type I migration of
the planet due to secular interactions with the disk material, the migration
rate depends linearly on the disk mass, and is independent of the initial
planet mass. For more massive disks, the planet can disturb the disk strongly
enough to trigger the collapse of gas into additional giant planets. When
additional planets form, their interaction as point masses dominates the
subsequent behavior of the system. This mechanism allows for the rapid
formation of Jupiter-mass and higher planets. Migration due to interaction with
the disk can significantly change the orbits of giant planets in gas disks.


title:
Spatially extended K I 7699 emission in the nebula of VY CMa: Kinematics
  and geometry

abstract:
  Long-slit echelle spectra reveal bright extended emission from the K I
lambda7699 resonance line in the reflection nebula surrounding the extreme red
supergiant VY Canis Majoris. The central star has long been known for its
unusually-bright K I emission lines, but this is the first report of intrinsic
emission from K I in the nebula. The extended emission is not just a reflected
spectrum of the star, but is due to resonant scattering by K atoms in the outer
nebula itself, and is therefore a valuable probe of the kinematics and geometry
of VY CMa's circumstellar environment. Dramatic velocity structure is seen in
the long-slit spectra, and most lines of sight intersect multiple distinct
velocity components. A faint ``halo'' at large distances from the star does
appear to show a reflected spectrum, however, and suggests a systemic velocity
of +40 km/s with respect to the Sun. The most striking feature is blueshifted
emission from the filled interior of a large shell seen in images; the
kinematic structure is reminiscent of a Hubble flow, and provides strong
evidence for asymmetric and episodic mass loss due to localized eruptions on
the star's surface.


title:
A Study of QSO Evolution in the X-Ray Band with the Aid of Gravitational
  Lensing

abstract:
  We present results from a mini-survey of relatively high redshift (1.7 < z <
4) gravitationally lensed radio-quiet quasars observed with the Chandra X-ray
Observatory and with XMM-Newton. The lensing magnification effect allows us to
search for changes in quasar spectroscopic and flux variability properties with
redshift over three orders of magnitude in intrinsic X-ray luminosity. It
extends the study of quasar properties to unlensed X-ray flux levels as low as
a few times 10^{-15} erg cm^{-2} s^{-1} in the observed 0.4-8 keV band. We find
a possible correlation between the X-ray powerlaw photon index and X-ray
luminosity of the gravitationally lensed radio-quiet quasar sample. The X-ray
spectral slope steepens as the X-ray luminosity increases. This correlation is
still significant when we combine our data with other samples of radio-quiet
quasars with z > 1.5, especially in the low luminosity range between
10^{43}-10^{45.5} erg s^{-1}. This result is surprising considering that such a
correlation is not found for quasars with redshifts below 1.5. We suggest that
this correlation can be understood in the context of the hot-corona model for
X-ray emission from quasar accretion disks, under the hypothesis that the
quasars in our sample accrete very close to their Eddington limits and the
observed luminosity range is set by the range of black hole masses (this
hypothesis is consistent with recent predictions of semi-analytic models for
quasar evolution). The upper limits of X-ray variability of our relatively high
redshift sample of lensed quasars are consistent with the known correlation
between variability and luminosity observed in Seyfert 1s when this correlation
is extrapolated to the larger luminosities of our sample.


title: Towards a Large Field of View Archive for the European VLBI Network

abstract:
  Traditionally VLBI observations focus on a small patch of sky and image
typically a few 100 mas around a bright source, which is often used to
self-calibrate the data. High spectral and time resolution is needed to image a
larger area, in principle up to the primary beam of the individual telescopes.
The EVN MkIV data processor at JIVE is being upgraded to make such high
resolution data its standard product. From the archive of high resolution data
it will be possible to image many sources in each field of view around the
original targets.


title:
A Friedmann-Lemaitre-Robertson-Walker cosmological model with running
  Lambda

abstract:
  The idea of a variable dark energy has been entertained many times in the
literature and from many different points of view. Quintessence is just a
popular way to implement this idea in recent times, but so far with little
success. Another possibility is to think of the cosmological term, Lambda, as a
``running quantity'' much in the same way as the electromagnetic coupling
constant. However, the fact that Lambda is a dimension-four parameter implies
that it may obey a peculiar renormalization group equation, which at low
energies could be dominated by ``soft decoupling'' contributions of the form
Lambda ~ H^2 M_P^2 stemming from physics near the Planck scale. This value lies
in the ballpark of the measurements from CMB and high-z supernovae. A
``renormalized'' FLRW cosmology of this kind may reveal itself as a sound, and
testable, proposal for a variable Lambda model within quantum field theory in
curved space time.


title: An exact model of conformal quintessence

abstract:
  A non--minimally coupled quintessence model is investigated and the
conditions for a stationary solution to the coincidence problem are obtained.
For a conformally coupled scalar field and dissipative matter, a general
solution possessing late acceleration is found. It fits rather well the high
redshift supernovae data and gives a good prediction of the age of the
Universe. Likewise, the cold dark matter component dominates the cosmological
perturbations at late times albeit they decrease with expansion.


title: On time evolution and causality of force-free black hole magnetospheres

abstract:
  The rotational energy of a Kerr black hole is often invoked as the free
energy source that powers compact astrophysical systems An important question
concerning the energy extraction mechanism is whether a Kerr black hole can
communicate stresses to a distant load via a surrounding, force-free
magnetosphere, and whether such structures are stable. In this paper we address
this question. We first re-examine the properties of short wavelength
force-free waves, and show that contrary to earlier claims, fast magnetosonic
disturbances do affect the global electric current flowing in the system, even
in flat spacetime; beyond the light cylinder the perturbed charge density is on
the order of the perturbed Goldreich-Julian charge density. This implies that
the fast magnetosonic surface is a causal wind boundary. We then go on to study
the evolution of a force-free system driven by a spinning-up black hole, by
solving the time dependent Maxwell equations near the horizon using
perturbation method. We find that the electromagnetic field, current and charge
density grow exponentially in the linear regime. We conclude that after time
$t=2M\ln(1/2\alpha^2)$, where $\alpha$ is the lapse function, the evolution
will reach an adiabatic stage, whereby the solution is to a good approximation
the static one, with the angular momentum of the hole being the adiabatic
parameter. This implies that black hole magnetospheres are stable. A brief
discussion on the relation between global current closure and causality in
force-free systems is given at the end.


title:
Shakura-Sunyaev Disk Can Smoothly Match Advection-Dominated Accretion
  Flow

abstract:
  We use the standard Runge-Kutta method to solve the set of basic equations
describing black hole accretion flows composed of two-temperature plasma. We do
not invoke any extra energy transport mechanism such as thermal conduction and
do not specify any ad hoc outer boundary condition for the advection-dominated
accretion flow (ADAF) solution. We find that in the case of high viscosity and
non-zero radiative cooling, the ADAF solution can have an asymptotic approach
to the Shakura-Sunyaev disk (SSD) solution, and the SSD-ADAF transition radius
is close to the central black hole. Our results further prove the mechanism of
thermal instability-triggered SSD-ADAF transition suggested previously by
Takeuchi & Mineshige and Gu & Lu.


title: Chandra Observations of the Optically Dark GRB030528

abstract:
  The X-ray-rich GRB030528 was detected by the HETE satellite and its
localization was rapidly disseminated. However, early optical observations
failed to detect a counterpart source. In a 2-epoch ToO observation with
Chandra, we discovered a fading X-ray source likely counterpart to GRB030528.
The source brightness was typical of X-ray afterglows observed at similar
epochs. Other observers detected an IR source at a location consistent with the
X-ray source. The X-ray spectrum is not consistent with a large absorbing
column.


title: Optical and X-ray Observations of the Afterglow to XRF030723

abstract:
  The X-ray-flash XRF030723 was detected by the HETE satellite and rapidly
disseminated, allowing for an optical transient to be detected ~1 day after the
burst. We discuss observations in the optical with Magellan, which confirmed
the fade of the optical transient. In a 2-epoch ToO observation with Chandra,
we discovered a fading X-ray source spatially coincident with the optical
transient. We present spectral fits to the X-ray data. We also discuss the
possibility that the source underwent a rebrightening in the X-rays, as was
observed in the optical. We find that the significance of a possible
rebrightening is very low (~1 sigma).


title:
Previously Claimed(/Unclaimed) X-ray Emission Lines in High Resolution
  Afterglow Spectra

abstract:
  We review the significance determination for emission lines in the Chandra
HETGS spectrum for GRB020813, and we report on a search for additional lines in
high resolution Chandra spectra. No previously unclaimed features are found. We
also discuss the significance of lines sets reportedly discovered using XMM
data for GRB011211 and GRB030227. We find that these features are likely of
modest, though not negligible, significance.


title: Gamma-ray Bursts and their Central Engines

abstract:
  Gamma-ray bursts are the most luminous and probably the most relativistic
events in the universe. The last few years have seen a tremendous increase in
our knowledge of these events, but the source of the bursts still remains
elusive. I will summarise recent progress in this field with special emphasis
on our understanding of the possible progenitor systems.


title:
An old galaxy group: Chandra X-ray observations of the nearby fossil
  group NGC 6482

abstract:
  We present the first detailed X-ray observations, using Chandra, of NGC 6482
- the nearest known `fossil group'. The group is dominated by an optically
luminous giant elliptical galaxy and all other known group members are at least
two magnitudes fainter. The global X-ray properties (luminosity, temperature,
extent) of NGC 6482 fall within the range of other groups, but the detailed
properties show interesting differences. We derive the gas temperature and
total mass profiles for the central 30 kpc using ACIS spatially resolved
spectroscopy. The temperature profile shows a continuous decrease outward,
dropping to 0.63 of its central value at 0.1 r_200. The derived total mass
profile is strongly centrally peaked, suggesting an early formation epoch.
These results support a picture in which fossil groups are old, giving time for
the most massive galaxies to have merged to produce a central giant elliptical
galaxy.
  Although the cooling time within 0.1 r_200 is less than a Hubble time, no
decrease in central temperature is detected. The entropy of the system lies
toward the low side of the distribution seen in poor groups, and it drops all
the way into the centre of the system, reaching very low values. No isentropic
core, such as those predicted in simple preheating models, is present. Given
the lack of any central temperature drop in the system, it seems unlikely that
radiative cooling can be invoked to explain this low central entropy. We find
that the centrally peaked temperature profile is consistent with a steady-state
cooling flow solution with an accretion rate of 2 solar mass per year, given
the large PdV work arising from the cuspy mass profile. However, solutions
involving distributed or non-steady heating cannot be ruled out.


title:
The Galactic Habitable Zone and the Age Distribution of Complex Life in
  the Milky Way

abstract:
  We modeled the evolution of the Milky Way to trace the distribution in space
and time of four prerequisites for complex life: the presence of a host star,
enough heavy elements to form terrestrial planets, sufficient time for
biological evolution and an environment free of life-extinguishing supernovae.
We identified the Galactic habitable zone (GHZ) as an annular region between 7
and 9 kiloparsecs from the Galactic center that widens with time and is
composed of stars that formed between 8 and 4 billion years ago. This GHZ
yields an age distribution for the complex life that may inhabit our Galaxy. We
found that 75% of the stars in the GHZ are older than the Sun.


title:
Environmental Effects in the Structural Parameters of Galaxies in the
  Coma Cluster

abstract:
  We have studied 116 bright galaxies from the Coma cluster brighter than
$m_{r}=17$ mag. From a quantitative morphological analysis we find that the
scales of the disks are smaller than those of field spiral galaxies. There is a
correlation between the scale of the disks and the position of the galaxy in
the cluster; no large disks are present near the center of the cluster or in
high density environments. The structural parameters of the bulges are not
affected by the environment. We have analyzed the distribution of blue and red
objects in the cluster. For spirals there is a trend between color and position
in the cluster. The bluest spiral galaxies are located at larger projected
radii; they also show larger velocity dispersions than the red ones. The
differences in the scale of the disks between cluster galaxies and local
samples of isolated galaxies and the color distribution of the objects can be
understood in terms of the harassment scenario.


title:
An XMM-Newton observation of the Seyfert 1 galaxy 1H 0419-577 in an
  extreme low state

abstract:
  Previous observations of the luminous Seyfert 1 galaxy 1H 0419-577 have found
its X-ray spectrum to range from that of a typical Seyfert 1 with 2-10 keV
power law index Gamma ~ 1.9 to a much flatter power law of Gamma ~ 1.5 or less.
We report here a new XMM-Newton observation which allows the low state spectrum
to be studied in much greater detail than hitherto. We find a very hard
spectrum (Gamma ~ 1.0), which exhibits broad features that can be modelled with
the addition of an extreme relativistic Fe K emission line or with partial
covering of the underlying continuum by a substantial column density of
near-neutral gas. Both the EPIC and RGS data show evidence for strong line
emission of OVII and OVIII requiring an extended region of low density
photoionised gas in 1H 0419-577. Comparison with an earlier XMM-Newton
observation when 1H 0419-577 was 'X-ray bright' indicates the dominant spectral
variability occurs via a steep power law component.


title: AM CVn systems as optical, X-ray and GWR sources

abstract:
  We discuss the model for the Galactic sample of the AM CVn systems with
orbital periods P less than 1500 s, that can be detected in the optical and/or
X-ray bands and may be resolved by the gravitational waves detector LISA. At
P=3 to 10 min all detectable systems are X-ray sources. At P greater than 10
min most systems are only detectable in the V-band. About 30% of the X-ray
sources is also detectable in the V-band. About 10,000 AM CVn systems might be
resolved by LISA; this is comparable to the number of detached double white
dwarfs that can be resolved. Several hundreds of AM CVn LISA sources might be
also detectable in the V- and/or X-ray bands.


title: Long-term variability in the X-ray emission of RX J0720.4-3125

abstract:
  We detect a gradual, long-term change in the shape of the X-ray spectrum of
the isolated neutron star RX J0720.4-3125, such that the spectrum of the source
can no longer be described as a blackbody spectrum. The change is accompanied
by an energy-dependent change in the pulse profile. If the X-ray emission is
influenced by the magnetic field of the pulsar, these changes in spectral shape
may point to precession of the neutron star.


title: A spectrophotometric study of RW Trianguli

abstract:
  On the basis of spectrophotometric observations we reconstruct the accretion
disk of the eclipsing novalike cataclysmic variable RW Tri in the wavelength
region 3600-7000 A. We find a radial temperature profile that is, on average,
consistent with that expected on the basis of the theory of optically thick,
steady state accretion disks and infer a mass-accretion rate in RW Tri of
\~10e-8 solar masses per year. The line emission is dominated by two areas: one
around the hot-spot region and one near the white dwarf. Both emission regions
have appreciable vertical extension, and seem to be decoupled from the velocity
field in the disk. In our observations RW Tri shows a number of features that
are characteristic of the SW Sex sub-class of novalike stars. The appearance of
a novalike system as a UX UMa/RW Tri or SW Sex star seems to be mainly governed
by the mass-transfer rate from the secondary at the time of observation.


title:
Rotation velocities of hot horizontal branch stars in the globular
  clusters NGC 1904, NGC 2808, NGC 6093, and NGC 7078: the database

abstract:
  We present radial and rotation (v sini) velocity measurements, from UVES+VLT
high resolution spectra of 61 stars in the blue horizontal branches (HB) of the
Galactic globular clusters NGC 1904 (M79), NGC 2808, NGC 6093 (M80), and NGC
7078 (M15).
  The data reduction and the velocity determination, based on cross-correlation
techniques, are discussed in detail. Most of this database has been used by
Recio-Blanco et al. (2002) in their analysis of the rotation velocity
properties of blue HB stars. Here we present additional data for NGC 2808. We
confirm the results of the previous paper, in particular, a possible link
between the HB jump and the abrupt change in the rotational velocity
distribution around Teff ~ 11,500 K.


title: Scalar field potentials for cosmology

abstract:
  We discuss different aspects of modern cosmology through a scalar field
potential construction method. We discuss the case of negative potential
cosmologies and its relation with oscillatory cosmic evolution, models with a
explicit interaction between dark energy and dark matter which address the
coincidence problem and also the case of non-zero curvature space.


title: Some Current Issues in Galaxy Formation

abstract:
  I describe recent challenges in hierarchical galaxy formation theory,
including the formation of disk galaxies and of ellipticals. Problems with cold
dark matter are summarized, and possible solutions are presented. I conclude
with a description of the prospects for observing one of the most important
ingredients in galaxy formation theory, namely cold dark matter.


title:
S-Z Anisotropy & Cluster Counts: Consistent Selection of sigma_8 and the
  Temperature-Mass Relation

abstract:
  The strong dependence of the mass variance parameter, sigma_8, on the adopted
cluster mass-temperature relation is explored. A recently compiled X-ray
cluster catalog and various mass-temperature relations are used to derive the
corresponding values of sigma_8. Calculations of the power spectrum of the CMB
anisotropy induced by the Sunyaev-Zeldovich effect and cluster number counts
are carried out in order to assess the need for a consistent choice of the
mass-temperature scaling and the parameter sigma_8. We find that the
consequences of inconsistent choice of the mass-temperature relation and
sigma_8 could be quite substantial, including a considerable mis-estimation of
the magnitude of the power spectrum and cluster number counts. Our results can
partly explain the large scatter between published estimates of the power
spectrum and number counts. We also show that the range of values of the
power-law index in the scaling C_l ~ sigma_8^[6-7] deduced in previous studies
is likely overestimated; we obtain a more moderate dependence, C_l ~
sigma_8^[4].


title:
A large population of 'Lyman-break' galaxies in a protocluster at
  redshift z=4.1

abstract:
  The most massive galaxies and the richest clusters are believed to have
emerged from regions with the largest enhancements of mass density relative to
the surrounding space. Distant radio galaxies may pinpoint the locations of the
ancestors of rich clusters, because they are massive systems associated with
overdensities of galaxies that are bright in the Lyman-alpha line of hydrogen.
A powerful technique for detecting high-redshift galaxies is to search for the
characteristic `Lyman break' feature in the galaxy colour, at wavelengths just
shortwards of Lya, due to absorption of radiation from the galaxy by the
intervening galactic medium. Here we report multicolour imaging of the most
distant candidate protocluster, TN J1338-1942 at a redshift z=4.1. We find a
large number of objects with the characteristic colours of galaxies at that
redshift, and we show that this excess is concentrated around the targeted
dominant radio galaxy. Our data therefore indicate that TN J1338-1942 is indeed
the most distant cluster progenitor of a rich local cluster, and that galaxy
clusters began forming when the Universe was only 10 per cent of its present
age.


title: Microlensing of Elliptical Sources by Fold Caustics

abstract:
  We consider microlensing of an elliptical source crossing a fold caustic. We
derive a simple expression for the light curve of a source with uniform surface
brightness that is accurate to third order in the ellipticity e (yielding
errors of <1% for e<0.3). We consider caustic crossings of a rotating star, an
oblate giant extrasolar planet, and an inclined standard thin accretion disk,
and find the following results. (1) If most stars have rotation periods similar
to chromospherically-active (i.e. spotted) giant stars in the bulge, than ~15%
should be sufficiently oblate (e>0.25) to produce detectable (>1%) deviations
with current observations. The form of the deviation due to ellipticity is
qualitatively similar to that due to limb-darkening. Thus stellar oblateness
may have to be taken into account in interpretations of precise limb-darkening
measurements with microlensing. (2) Giant planets will generally not produce a
detectable oblateness signal, either because they rotate too slowly (if they
are close-in and tidally locked), or because they are too faint (if they are
farther away from the parent star). (3) There is a near-degeneracy between
ellipticity and position angle for equal-area sources with scale-free intensity
profiles and elliptical isophotes. This degeneracy results in a factor of ~2
uncertainty in the measurement of the scale-length of a standard thin accretion
disk using observations of a single, linear fold crossing quasar microlensing
event in passbands probing the outer parts of the disk. Higher-frequency
observations can reduce this uncertainty.


title:
The Local Ly-alpha Forest IV: STIS G140M Spectra and Results on the
  Distribution and Baryon Content of HI Absorbers

abstract:
  We present HST STIS/G140M spectra of 15 extragalactic targets, which we
combine with GHRS/G160M data to examine the statistical properties of the low-z
Ly-alpha forest. We evaluate the physical properties of these Ly-alpha
absorbers and compare them to their high-z counterparts. We determine that the
warm, photoionized IGM contains 29+/-4% of the total baryon inventory at z = 0.
We derive the distribution in column density, N_HI^(1.65+/-0.07) for 12.5 < log
[N_HI] < 14.5, breaking to a flatter slope above log [N_HI] > 14.5. The slowing
of the number density evolution of high-W Ly-alpha clouds is not as great as
previously measured, and the break to slower evolution may occur later than
previously suggested (z~1.0 rather than 1.6). We find a 7.2sigma excess in the
two-point correlation function (TPCF) of Ly-alpha absorbers for velocity
separations less than 260 km/s, which is exclusively due to the higher column
density clouds. From our previous result that higher column density Ly-alpha
clouds cluster more strongly with galaxies, this TPCF suggests a physical
difference between the higher and lower column density clouds in our sample.


title:
The Gemini Deep Deep Survey: III. The abundance of massive galaxies 3-6
  billion years after the Big Bang

abstract:
  Hierarchical galaxy formation is the model whereby massive galaxies form from
an assembly of smaller units. The most massive objects therefore form last. The
model succeeds in describing the clustering of galaxies, but the evolutionary
history of massive galaxies, as revealed by their visible stars and gas, is not
accurately predicted. Near-infrared observations (which allow us to measure the
stellar masses of high-redshift galaxies) and deep multi-colour images indicate
that a large fraction of the stars in massive galaxies form in the first 5 Gyr,
but uncertainties remain owing to the lack of spectra to confirm the redshifts
(which are estimated from the colours) and the role of obscuration by dust.
Here we report the results of a spectroscopic redshift survey that probes the
most massive and quiescent galaxies back to an era only 3 Gyr after the Big
Bang. We find that at least two-thirds of massive galaxies have appeared since
this era, but also that a significant fraction of them are already in place in
the early Universe.


title:
Period-luminosity relations for Galactic Cepheid variables with
  independent distance measurements

abstract:
  In this paper, we derive the period-luminosity (PL) relation for Galactic
Cepheids with recent independent distance measurements from open cluster,
Barnes-Evans surface brightness, interferometry and HST astrometry techniques.
Our PL relation confirms the results of Tammann et al. (2003), which showed
that the Galactic Cepheids follow a different PL relation to their LMC
counterparts. Our results also show that the slope of the Galactic PL relation
is inconsistent with the LMC slope with more than 95% confidence level. We
apply this Galactic PL relation to find the distance to NGC 4258. Our result of
mu_o=29.49\pm0.06(random error)mag. agrees at the ~1.4sigma level with the
geometrical distance of \mu_{geo}=29.28\pm0.15mag. from water maser
measurements..


title: Power Spectrum Analysis of the 2dF QSO Sample Revisited

abstract:
  We revisit the power spectrum analysis of the complete sample of the two
degree field (2dF) QSO redshift (2QZ) survey, as a complementary test of the
work by Outram et al. (2003). A power spectrum consistent with that of the 2QZ
group is obtained. Differently from their approach, fitting of the power
spectrum is investigated incorporating the nonlinear effects, the geometric
distortion and the light-cone effect. It is shown that the QSO power spectrum
is consistent with the $\Lambda$ cold dark matter (CDM) model with the matter
density parameter $\Omega_m=0.2\sim0.5$. Our constraint on the density
parameter is rather weaker than that of the 2QZ group. We also show that the
constraint slightly depends on the equation of state parameter $w$ of the dark
energy. The constraint on $w$ from the QSO power spectrum is demonstrated,
though it is not very tight.


title:
Gravitational Lensing by Dark Matter Halos with Non-universal Density
  Profiles

abstract:
  The statistics of gravitational lensing can provide us with a very powerful
probe of the mass distribution of matter in the universe. By comparing
predicted strong lensing probabilities with observations, we can test the mass
distribution of dark matter halos, in particular, the inner density slope. In
this letter, unlike previous work that directly models the density profiles of
dark matter halos semi-analytically, we generalize the density profiles of dark
matter halos from high-resolution N-body simulations by means of generalized
Navarro-Frenk-White (GNFW) models of three populations with slopes, $\alpha$,
of about -1.5, -1.3 and -1.1 for galaxies, groups and clusters, respectively.
This approach is an alternative and independent way to examine the slopes of
mass density profiles of halos. We present calculations of lensing
probabilities using these GNFW profiles for three populations in various
spatially flat cosmological models with a cosmological constant $\Lambda$. It
is shown that the compound model of density profiles does not match well with
the observed lensing probabilities derived from the Jodrell-Bank VLA
Astrometric Survey data in combination with the Cosmic Lens All-Sky Survey
data. Together with the previous work on lensing probability, our results
suggest that a singular isothermal sphere mass model of less than about
$10^{13}h^{-1}M_{\sun}$ can predict strong lensing probabilities that are
consistent with observations of small splitting angles.


title: Implementing an Observatory Control System-I. A Generic Approach

abstract:
  An architectural framework for implementing a distributed observatory control
system is presented here. It has been partially realized and tested in the 2m
optical and infrared Observatory at Pune, India.


title: Optical Nuclei of Radio-loud AGN and the Fanaroff-Riley Divide

abstract:
  We investigate the nature of the point-like optical ``cores'' that have been
found in the centres of the host galaxies of a majority of radio galaxies by
the Hubble Space Telescope. We examine the evidence that these optical cores
are relativistically beamed, and look for differences in the behaviour of the
cores found in radio galaxies of the two Fanaroff-Riley types. We also attempt
to relate this behaviour to the properties of the optical nuclei in their
highly beamed counterparts (the BL Lac objects and radio-loud quasars) as
hypothesized by the simple Unified Scheme. Simple model-fitting of the data
suggests that the emission may be coming from a non-thermal relativistic jet.
It is also suggestive that the contribution from an accretion disk is not
significant for the FRI objects and for the narrow-line radio galaxies of FRII
type, while it may be significant for the Broad-line objects, and consistent
with the idea that the FRII optical cores seem to suffer from extinction due to
an obscuring torus while the FRI optical cores do not. These results are in
agreement with the Unified Scheme for radio-loud AGNs.


title: Merging of Low-Mass Systems and the Origin of the Fundamental Plane

abstract:
  We present a new set of dissipationless N-body simulations to examine the
feasibility of creating bright ellipticals (following the Kormendy relation) by
hierarchically merging present-day early-type dwarf galaxies, and to study how
the encounter parameters affect the location of the end-product in the
$<\mu_{e} > - R_{e}$ plane. We investigate the merging of one-component
galaxies of both equal and different masses, the merging of two-component
galaxy models to explore the effect of dark halos on the final galaxy
characteristics, and the merging of ultracompact dwarf galaxies. We find that
the increase of $<\mu_{e}>$ with $R_e$ is attributable to an increase in the
initial orbital energy. The merger remnants shift down in the $<\mu_{e} > -
R_{e}$ plane and fail to reach the KR. Thus, the KR is not reproducable by
mergers of dwarf early-type systems, rendering untenable the theory that
present-day dwarfs are responsible for even a small fraction of the present-day
ellipticals, unless a considerable amount of dissipation is invoked. However,
we do find that present-day dwarfs can be formed by the merger of ultra-compact
dwarfs.


title:
Peak Energy-Isotropic Energy Relation in the Off-Axis Gamma-Ray Burst
  Model

abstract:
  Using a simple uniform jet model of prompt emissions of gamma-ray bursts
(GRBs), we reproduce the observed peak energy--isotropic energy relation. A
Monte Carlo simulation shows that the low-isotropic energy part of the relation
is dominated by events viewed from off-axis directions, and the number of the
off-axis events is about one-third of the on-axis emissions. We also compute
the observed event rates of the GRBs, the X-ray-rich GRBs, and the X-ray
flashes detected by HETE-2, and we find that they are similar.


title: $^{12}$C/$^{13}$C ratio in planetary nebulae from the IUE archives

abstract:
  We investigated the abundance ratio of $^{12}$C/$^{13}$C in planetary nebulae
by examining emission lines arising from \ion{C}{3} $2s2p ^3P_{2,1,0} \to 2s^2
^1S_0$. Spectra were retrieved from the International Ultraviolet Explorer
archives, and multiple spectra of the same object were coadded to achieve
improved signal-to-noise. The $^{13}$C hyperfine structure line at 1909.6 \AA
was detected in NGC 2440. The $^{12}$C/$^{13}$C ratio was found to be
$\sim4.4\pm$1.2. In all other objects, we provide an upper limit for the flux
of the 1910 \AA line. For 23 of these sources, a lower limit for the
$^{12}$C/$^{13}$C ratio was established. The impact on our current
understanding of stellar evolution is discussed.
  The resulting high signal-to-noise \ion{C}{3} spectrum helps constrain the
atomic physics of the line formation process. Some objects have the measured
1907/1909 flux ratio outside the low-electron density theoretical limit for
$^{12}$C. A mixture of $^{13}$C with $^{12}$C helps to close the gap somewhat.
Nevertheless, some observed 1907/1909 flux ratios still appear too high to
conform to the presently predicted limits. It is shown that this limit, as well
as the 1910/1909 flux ratio, are predominantly influenced by using the standard
partitioning among the collision strengths for the multiplet $^1S_0$--$^3P_J$
according to the statistical weights. A detailed calculation for the fine
structure collision strengths between these individual levels would be
valuable.


title: Galaxy Interaction and Starburst-Seyfert Connection

abstract:
  Galaxy interactions are studied in terms of the starburst-Seyfert connection.
The starburst requires a high rate of gas supply. Since the efficiency for
supplying the gas is high in a galaxy interaction, although the companion is
not necessarily discernible, Seyfert galaxies with circumnuclear starbursts are
expected to be interacting. Since the large amounts of circumnuclear gas and
dust obscure the broad-line region, they are expected to be observed as Seyfert
2. The active galactic nucleus itself does not require a high rate of gas
supply. Seyfert galaxies without circumnuclear starbursts are not necessarily
expected to be interacting even at the highest luminosities. They are not
necessarily expected to evolve from Seyfert galaxies with circumnuclear
starbursts. We derive these and other theoretical expectations and confirm them
with statistics on observational data of magnitude-limited samples of Seyfert
galaxies.


title:
A deeper view of Extremely Red Galaxies: the redshift distribution in
  the GOODS/CDFS ISAAC field

abstract:
  We have analysed 5-epoch GOODS HST-ACS B, V, I_775 and z datasets (V1.0
release), in conjunction with existing VLT-ISAAC imaging in the J, H and Ks
bands, to derive estimated redshifts for the sample of 198 Extremely Red
Galaxies (ERGs) with Ks<22 (Vega) and I_775-Ks>3.92 selected by Roche et
al.(2003) from 50.4 sq.arcmin of the GOODS/CDFS field. We find that, at this
depth, the ERG population spans the redshift range 0.5<z_phot<4.75 and over two
decades in mass (~ 3x10^9 M_sun to ~3x10^11 M_sun). We explore the evolution of
the ERG luminosity function (LF) from redshifts <z_phot>=1.0 to <z_phot>=2.5
and compare it with the global Ks-band LF at redshifts 1<z_phot<2. We find that
the bright end of the ERG LF does not decrease from redshifts <z_phot>=2.0 to
<z_phot>=2.5 and we connect this fact with the presence of progenitors of the
local L>L* population at redshifts z_phot>2. We determine lower limits of
rho_c=(6.1 +/- 1.9) x 10^{-5} Mpc^{-3} and rho_c=(2.1 +/- 1.1) x
10^{-5}Mpc^{-3} on the comoving densities of progenitors of local massive
galaxies already assembled at redshifts <z_phot>=2.5 and <z_phot>=3.5,
respectively. We have investigated the existence of high-redshift Lyman break
galaxies massive enough to be included in this ERG sample. Out of an initial
list of 12 potential very high redshift candidates, we have identified 2 ERGs
which have a high probability of lying at z_phot>4. We discuss the advantages
of multi-colour to single-colour selection techniques in obtaining reliable
lists of very high-redshift candidate sources, and present revised lower
redshift estimates for sources previously claimed as potential z> 5 dropouts in
recent studies.(abridged)


title:
No magnetic field variation with pulsation phase in the roAp star gamma
  Equulei

abstract:
  We present an analysis of 210 high-resolution time-resolved
spectropolarimetric observations of the roAp star gamma Equ obtained over three
nights in August and September 2003. Radial velocity variations due to p-mode
non-radial pulsations are clearly detected in the lines of rare-earth elements,
in particular Pr III, Nd II and Nd III. In contrast, we find absolutely no
evidence for the variation of the mean longitudinal magnetic field over the
pulsation period in gamma Equ at the level of 110-240 G which was recently
reported by Leone & Kurtz (2003). Our investigation of the variability of
circularly polarized profiles of 13 Nd III lines demonstrates that, at the 3
sigma confidence level, no magnetic field variation with an amplitude above
40-60 G was present in gamma Equ during our monitoring of this star.


title: Decomposition of AGN host galaxy images

abstract:
  We describe an algorithm to decompose deep images of Active Galactic Nuclei
into host galaxy and nuclear components. Currently supported are three galaxy
models: A de-Vaucouleurs spheroidal, an exponential disc, and a two-component
disc+bulge model. Key features of the method are: (semi-)analytic
representation of a possibly spatially variable point-spread function; full
two-dimensional convolution of the model galaxy using gradient-controlled
adaptive subpixelling; multiple iteration scheme. The code is computationally
efficient and versatile for a wide range of applications. The quantitative
performance is measured by analysing simulated imaging data. We also present
examples of the application of the method to small test samples of nearby
Seyfert 1 galaxies and quasars at redshifts z < 0.35.


title:
Morphology and Redshifts of Extremely Red Galaxies in the GOODS/CDFS
  deep ISAAC field

abstract:
  We present the photometric redshift distribution of a sample of 198 Extremely
Red Galaxies (ERGs) with Ks<22 and I-Ks>3.92 (Vega), selected by Roche et al.
in 50.4 sq. arcmin of the Chandra Deep Field South (CDFS). The sample has been
obtained using ISAAC-VLT and ACS-HST GOODS public data. We also show the
results of a morphological study of the 72 brightest ERGs in the z band (z<25,
AB).


title:
Integral Field Spectroscopy of Extended Lyman-alpha Emission from the
  DLA Galaxy in Q2233+131

abstract:
  This paper presents observations of an extended Lyman-alpha emission nebula
surrounding the galaxy responsible for the Damped Lyman-alpha Absorption (DLA)
line in the spectrum of the quasar Q2233+131. With the Potsdam Multi Aperture
Spectrophotometer (PMAS) we measure the properties of the extended Ly-alpha
emission in an area of 3"* 5" having a total line flux of (2.8+/-0.3)*10^{-16}
erg cm-2 s-1, which at redshift z=3.15 corresponds to a luminosity of (2.4
-0.2/+0.3)*10^{43} erg s-1 and a size of 23 times 38 kpc. The location of the
emission is spatially coincident with the previously detected DLA galaxy, but
extends significantly beyond its limb. We argue that the Ly-alpha emission is
likely to be caused by an outflow from the DLA galaxy, presumably powered by
star formation. In the case of negligible dust extinction, the Ly-alpha
luminosity indicates a star-formation rate of 19+/-10 solar masses per year
consistent with that derived from the UV continuum flux from the parent galaxy.
The wind velocity indicated by the integral field spectra is of the order of
several hundred km s-1. We find no indication of emission originating in a
rotating disk.


title: A synthetic view on structure and evolution of the Milky Way

abstract:
  Since the Hipparcos mission and recent large scale surveys in the optical and
the near-infrared, new constraints have been obtained on the structure and
evolution history of the Milky Way. The population synthesis approach is a
useful tool to interpret such data sets and to test scenarios of evolution of
the Galaxy. We present here new constraints on evolution parameters obtained
from the Besancon model of population synthesis and analysis of optical and
near-infrared star counts. The Galactic potential is computed
self-consistently, in agreement with Hipparcos results and the observed
rotation curve. Constraints are posed on the outer bulge structure, the warped
and flared disc, the thick disc and the spheroid populations. The model is
tuned to produce reliable predictions in the visible and the near-infrared in
wide photometric bands from U to K. Finally, we describe applications such as
photometric and astrometric simulations and a new classification tool based on
a Bayesian probability estimator, which could be used in the framework of
Virtual Observatories. As examples, samples of simulated star counts at
different wavelengths and directions are also given.


title: Integral field observations of DLA galaxies

abstract:
  We report preliminary results from a targeted investigation on quasars
containing damped Lyman-alpha absorption (DLA) lines as well strong metal
absorption lines, carried out with the Potsdam Multi Aperture Spectrophotometer
(PMAS). We search for line-emitting objects at the same redshift as the
absorption lines and close to the line of sight of the QSOs. We have observed
and detected the already confirmed absorbing galaxies in Q2233+131 (z_abs=3.15)
and Q0151+045 (z_abs=0.160), while failing to find spectral signatures for the
z=0.091 absorber in Q0738+313. From the Q2233+131 DLA galaxy, we have detected
extended Ly-alpha emission from an area of 3"*5".


title:
The XMM Large Scale Structure (XMM-LSS) Survey: X-ray analysis and first
  results

abstract:
  Thanks to its unprecedented sensitivity and large field of view, XMM occupies
a leading position as a survey instrument. The XMM-LSS survey is a medium-deep
large-area X-ray survey, and greatly extends the cosmological tests attempted
using earlier studies. While a wealth of complementary multiwavelength studies
are taking place, I concentrate here on the XMM-EPIC data, describing aspects
of the X-ray pipeline and analysis, and selected first results, including the
deepest wide-angle X-ray image of the cosmos to date.


title:
Spatial and Temporal Variations of Light Curves in Gravitationally
  Lensed Sources

abstract:
  Effects of macro-and microlensing on the spatial and temporal characteristics
of images of remote sources, observed through the inner regions of lensing
galaxies are discussed. A particular attention was given to the case, when
microlenses, - stars, star-like or planetary bodies, - are situated near the
critical curves of macrolenses, - galaxies, stellar clusters, etc. The
investigation is of interest for the gravitational lens (GL) systems, where the
lensed images are observed close to the critical curve of a macrolens. Annular,
arched or confluent images should be regarded as an indication to such a
proximity. Numerical simulation allowed to determine the structure of critical
curves and caustics, formed by macro and microlenses, and to evaluate possible
distortions, caused by microlenses for various locations with respect to the
critical curve of a regular lens. The difference of our results from those
obtained earlier with the standard (linearized) approach to describe the
regular gravitational lens was shown to be the larger the closer to the
critical curve the microlenses are situated. In addition to spatial
redistributions in the visible images, complicated deformation of their light
curves occurs in gravitational lensing of variable in time and extended
sources. The magnitude of the temporal variations depend not only on the GL
parameters (e.g., mass distribution), but on the parameters of the source as
well, such as linear dimension of the emitting region, its location with
respect to the critical curve, and the impulse duration. The analysis shows,
that in this case GL acts as a filter, which passes slow temporal variations
without degradations, and smoothes the rapid ones.


title: Rings in the Haloes of Planetary Nebulae

abstract:
  We present a search for rings or arcs in the haloes of planetary nebulae
(PNe). We discovered such structures in eight PNe, tripling the sample of PNe
with known rings. This shows that, contrary to what was believed to date, the
occurrence of mass loss fluctuations with timescales of ~100 to ~1000 yrs at
the end of the asymptotic giant branch phase (AGB) is common. We estimate a
lower limit of the occurrence rate of rings in PN haloes to be ~35%.
  Using these new detections and the cases previously known, we discuss the
statistical properties of ring systems in PNe haloes. We estimate that the mass
modulation producing the rings takes place during the last 10 or 20 kyrs of AGB
evolution. In PNe, the spacing between rings ranges from <0.01 pc to 0.06 pc,
significantly larger than those seen in proto-PNe. This, together with the
finding of a possible positive correlation of spacing with the post-AGB age of
the nebulae, suggests that the spacing of the rings increases with time.
  These properties, as well as the modest surface brightness amplitudes of
rings, are consistent with the predictions of the dust-driven wind instability
model explored by Meijerink et al. (2003), but do not immediately exclude other
proposed models.


title:
Box- and peanut-shaped bulges. III. A new class of bulges: Thick Boxy
  Bulges

abstract:
  Inspecting all 1224 edge-on disk galaxies larger than 2' in the RC3 on DSS
images we have found several galaxies with extraordinary bulges meeting two
criteria: They are box shaped and large in respect to the diameters of their
galaxies. These bulges are often disturbed, show frequently prominent
irregularities and asymmetries, and some possess possible merger remnants or
merging satellites. For these bulges we have introduced the term "Thick Boxy
Bulges" (TBBs). About 2% of all disk galaxies (S0-Sd), respectively 4% of all
galaxies with box- and peanut-shaped (b/p) bulges, belong to this class of
galaxies. Using multicolour CCD and NIR data we have enlarged and followed up
our sample of nearly 20 galaxies with a TBB. The disturbed morphology of a
large fraction of these galaxies shows that many of the TBB galaxies are not
dynamically settled. For the TBBs the extent of the box shape seems to be too
large to result from a normal bar potential. Therefore we conclude that two
classes of b/p bulges exist with different origins. While most (~96%) b/p
bulges can be explained by bars alone, the extended boxy structures of TBBs
result most likely from accreted material by infalling satellite companions
(soft merging).


title:
Luminous hot accretion flows: the origin of X-ray emission of Seyfert
  galaxies and black hole binaries

abstract:
  We investigate accretion disc models for the X-ray emission of Seyfert-1
galaxies and the hard state of black-hole X-ray binaries. We concentrate on two
hot accretion disc models: advection-dominated accretion flow (ADAF) and
recently found luminous hot accretion flow (LHAF). We solve for the global
solution of both ADAF and LHAF to obtain the electron temperature, $T_{\rm e}$,
and Thompson optical depth, $\tau$, at the radius where most of the radiation
comes from. We adopt two kinds of electron energy equations. In one, only
synchrotron and bremsstrahlung radiation and their Comptonization are
considered. The other is parameterized by a constant Compton parameter to model
the case in which thermal Comptonization of external soft photon is important.
We compare the calculated $T_{\rm e}$ and $\tau$ with the observational values
obtained by fitting the average spectra of Seyfert-1 galaxies and black-hole
binaries using thermal Comptonization model. We find that the most favoured
model is an LHAF with parameterized electron energy equation, with ADAFs
predicting too high $T_{\rm e}$.


title: Massive star formation: Nurture, not nature

abstract:
  We investigate the physical processes which lead to the formation of massive
stars. Using a numerical simulation of the formation of a stellar cluster from
a turbulent molecular cloud, we evaluate the relevant contributions of
fragmentation and competitive accretion in determining the masses of the more
massive stars. We find no correlation between the final mass of a massive star,
and the mass of the clump from which it forms. Instead, we find that the bulk
of the mass of massive stars comes from subsequent competitive accretion in a
clustered environment. In fact, the majority of this mass infalls onto a
pre-existing stellar cluster. Furthermore, the mass of the most massive star in
a system increases as the system grows in numbers of stars and in total mass.
This arises as the infalling gas is accompanied by newly formed stars,
resulting in a larger cluster around a more massive star. High-mass stars gain
mass as they gain companions, implying a direct causal relationship between the
cluster formation process, and the formation of higher-mass stars therein.


title: Core-collapse supernovae and gravitational waves

abstract:
  Core-collapse supernovae are dramatic events with a rich phenomenology,
including gravitational radiation. Simulations of these events in multiple
spatial dimensions with energy- and angle-dependent neutrino transport are
still in their infancy. Core collapse and bounce in a supernova in our galaxy
may well be visible by first-generation LIGO, but detailed understanding waits
on improvements in modeling both stellar progenitors and the supernova process.


title: Star-forming Galaxies in the 'Redshift Desert'

abstract:
  We describe results of optical and near-IR observations of a large
spectroscopic sample of star-forming galaxies photometrically-selected to lie
in the redshift range 1.4 < z < 2.5, often called the ``redshift desert''
because of historical difficulty in obtaining spectroscopic redshifts in this
range. We show that the former ``redshift desert'' is now very much open to
observation.


title: IR and Optical Observations of GRB 030115

abstract:
  We present an upper limit on the brightness of the afterglow of the long GRB
030115 measured from Infrared (IR) images taken with the Magellan Classic Cam
instrument of Ks > 22 at 6.2 days after the burst. We also present measurments
of the host galaxy of GRB 030115 from archival optical and IR HST images taken
with the Advanced Camera for Surveys and the Near Infrared Camera and Multi
Object Spectrometer 25+ days after the burst. GRB 030115 is classified as an
Optically Dark Burst, as its afterglow was found in the J, H, and K IR bands
after a null result was reported in the optical. This is the first HETE GRB to
have its afterglow found initially in the IR.


title: Astrophysical False Positives Encountered in Wide-Field Transit Searches

abstract:
  Wide-field photometric transit surveys for Jupiter-sized planets are
inundated by astrophysical false positives, namely systems that contain an
eclipsing binary and mimic the desired photometric signature. We discuss
several examples of such false alarms. These systems were initially identified
as candidates by the PSST instrument at Lowell Observatory. For three of the
examples, we present follow-up spectroscopy that demonstrates that these
systems consist of (1) an M-dwarf in eclipse in front of a larger star, (2) two
main-sequence stars presenting grazing-incidence eclipses, and (3) the blend of
an eclipsing binary with the light of a third, brighter star. For an additional
candidate, we present multi-color follow-up photometry during a subsequent time
of eclipse, which reveals that this candidate consists of a blend of an
eclipsing binary and a physically unassociated star. We discuss a couple
indicators from publicly-available catalogs that can be used to identify which
candidates are likely giant stars, a large source of the contaminants in such
surveys.


title: Thermal structure of gas in relaxed clusters of galaxies

abstract:
  Gas clouds under the influence of gravitation in thermodynamic equilibrium
cannot be isothermal due to the Dufour effect, the energy flux induced by
density gradients. In galaxy clusters this effect may be responsible for most
of the "cooling flows" instead of radiative cooling of the gas. Observations
from XMM-Newton and Chandra satellites agree well with model calculations,
assuming equilibrium between energy flux induced by temperature and density
gradients, but without radiation loss.


title: Simulated Radio Images and Light Curves of SN 1993J

abstract:
  We present calculations of the radio images and light curves from supernovae,
based on high-resolution numerical simulations of the hydrodynamics and
radiation transfer in a spherically symmetric medium. As a specific example we
model the emission from SN1993J. This supernova does not appear to be expanding
in a self-similar fashion, and cannot be adequately fitted with the often-used
analytic mini-shell model. We present a good fit to the radio evolution at a
single frequency. Both free-free absorption and synchrotron self-absorption are
needed to fit the light curve at early times, and a circumstellar density
profile of $\rho \sim r ^{-1.7}$ provides the best fit to the later data.
Comparisons of VLBI images of SN1993J with synthetic model images suggest that
internal free-free absorption completely obscures emission at 8.4 GHz passing
through the center of the supernova for the first few tens of years after
explosion.


title: Stellar Rotation and the Formation of Asymmetric Nebulae

abstract:
  We illustrate how rotation of the central star can give rise to latitudinal
variations in the wind properties from the star. Interaction of these winds
with the surrounding medium can produce asymmetrical planetary nebulae.


title:
Multifrequency Observations of Radio Pulse Broadening and Constraints on
  Interstellar Electron Density Microstructure

abstract:
  We have made observations of 98 low-Galactic-latitude pulsars to measure
pulse broadening caused by multipath propagation through the interstellar
medium. Data were collected with the 305-m Arecibo telescope at four radio
frequencies between 430 and 2380 MHz. We used a CLEAN-based algorithm to
deconvolve interstellar pulse broadening from the measured pulse shapes. We
employed two distinct pulse broadening functions (PBFs): PBF$_1$ is appropriate
for a thin screen of scattering material between the Earth and a pulsar, while
PBF$_2$ is appropriate for scattering material uniformly distributed along the
line of sight from the Earth to a pulsar. We found that some observations were
better fit by PBF$_1$ and some by PBF$_2$. Pulse broadening times ($\tau_d$)
are derived from fits of PBFs to the data, and are compared with the
predictions of a smoothed model of the Galactic electron distribution. Several
lines of sight show excess broadening, which we model as clumps of high density
scattering material. A global analysis of all available data finds that the
pulse broadening scales with frequency, $\nu$, as $\taud \propto\nu^{-\alpha}$
where $\alpha\sim 3.9\pm 0.2$. This is somewhat shallower than the value
$\alpha=4.4$ expected from a Kolmogorov medium, but could arise if the spectrum
of turbulence has an inner cutoff at $\sim $300--800 km. A few objects follow
particularly shallow scaling laws (the mean scaling index $\meanalpha \sim 3.1
\pm 0.1$ and $ \sim 3.8 \pm 0.2$ respectively for the case of PBF$_1$ and
PBF$_2$), which may arise from large scale refraction or from the truncation of
scattering screens transverse to the Earth--pulsar line of sight.


title:
A High-Resolution Very Large Array Observation of a Protostar in OMC-3:
  Shock-induced X-ray Emission by a Protostellar Jet

abstract:
  Using the Very Large Array (VLA) in the A-configuration, we have obtained a
high-resolution 3.6 cm map of a hard X-ray source detected by the Chandra X-ray
Observatory in a protostellar clump in Orion molecular cloud 3. Two radio
continuum sources were detected in the vicinity of the X-ray source, both of
which have NIR counterparts. We conclude that these VLA sources are free-free
emission produced by shocks in protostellar jets from the NIR class I
protostars. Using the centimeter data, we determined the power and orientation
of the protostellar jets. The center position of the X-ray emission was found
to be ~1--2" offset from the exciting sources of the jets, and the displacement
is in the direction of the jets and molecular outflows. We discuss the nature
of the X-ray emission as the shock-excited plasma at the shock front where the
jet propagates through interstellar medium at a speed of ~1000 km/s.


title:
An extensive library of synthetic spectra covering the far red, RAVE and
  GAIA wavelength ranges

abstract:
  A library of 183588 synthetic spectra based on Kurucz's ATLAS9 models is
presented for the far red spectral interval (7653 -- 8747\AA). It is
characterized by 3500 K <= T_eff <= 47500 K, 0.0 <= log g <= 5.0, -3.0 <= [M/H]
<= +0.5, 0 <= V_rot <= 500 km/s, xi = 2 km/s. The whole grid of spectra is
calculated for resolving powers 8500, 11500 and 20000. A section of the grid is
also computed for [alpha/Fe]=+0.4 and for microturbulent velocities 0 and 4
km/s. The library covers the wavelength ranges and resolutions of the two
ambitious spectroscopic surveys by the ground experiment RAVE and the space
mission GAIA. Cross-sections across the multi-dimensional data-cube are used to
illustrate the behaviour of the strongest spectral lines. Interpretation of
real data will have to include interpolation to grid substeps. We present a
simple estimate of the accuracy of such a procedure.


title: CMB Anisotropies Reveal Quantized Gravity

abstract:
  A novel primordial spectrum with a dynamical scale of quantum gravity origin
is proposed to explain the sharp fall off of the angular power spectra at low
multipoles in the COBE and WMAP observations. The spectrum is derived from
quantum fluctuations of the scalar curvature in a renormalizable model of
induced gravity. This model describes the very early universe by the conformal
field fluctuating about an inflationary background with the expansion time
constant of order of the Planck mass.


title:
Probing the atmosphere of the bulge G5III star OGLE-2002-BUL-069 by
  analysis of microlense H alpha line

abstract:
  We discuss high-resolution, time-resolved spectra of the caustic exit of the
binary microlensing event OGLE 2002-BUL-69 obtained with UVES on the VLT. The
source star is a G5III giant in the Galactic Bulge. During such events, the
source star is highly magnified, and a strong differential magnification around
the caustic resolves its surface. Using an appropriate model stellar atmosphere
generated by the NextGEN code we obtained a model light curve for the caustic
exit and compared it with a dense set of photometric observations obtained by
the PLANET microlensing follow up network. We further compared predicted
variations in the H alpha equivalent width with those measured from our
spectra. While the model and observations agree in the gross features, there
are discrepancies suggesting shortcomings in the model, particularly for the H
alpha line core, where we have detected amplified emission from the stellar
chromosphere as the source star's trailing limb exited the caustic. This
achievement became possible by the provision of the OGLE-III Early Warning
System, a network of small telescopes capable of nearly-continuous
round-the-clock photometric monitoring, on-line data reduction, daily
near-real-time modelling in order to predict caustic crossing parameters, and a
fast and efficient response of a 8m-class telescope to a
``Target-Of-Opportunity'' observation request.


title: An updated nuclear reaction network for BBN

abstract:
  The key Standard-Physics inputs of the Big Bang Nucleosynthesis (BBN) are the
light nuclei reaction rates. Both the network and the nuclear rates have been
recently reanalyzed and updated, and cosmological and New-Physics constraints
(taking into account the WMAP Cosmic Microwave Background anisotropies
measurement) obtained with a new code are presented.


title: Combined BIMA and OVRO observations of comet C/1999 S4 (LINEAR)

abstract:
  We present results from an observing campaign of the molecular content of the
coma of comet C/1999 S4 (LINEAR) carried out jointly with the millimeter-arrays
of the Berkeley-Illinois-Maryland Association (BIMA) and the Owens Valley Radio
Observatory (OVRO). Using the BIMA array in autocorrelation (`single-dish')
mode, we detected weak HCN J=1-0 emission from comet C/1999 S4 (LINEAR) at 14
+- 4 mK km/s averaged over the 143" beam. The three days over which emission
was detected, 2000 July 21.9-24.2, immediately precede the reported full
breakup of the nucleus of this comet. During this same period, we find an upper
limit for HCN 1-0 of 144 mJy/beam km/s (203 mK km/s) in the 9"x12" synthesized
beam of combined observations of BIMA and OVRO in cross-correlation (`imaging')
mode. Together with reported values of HCN 1-0 emission in the 28" IRAM
30-meter beam, our data probe the spatial distribution of the HCN emission from
radii of 1300 to 19,000 km. Using literature results of HCN excitation in
cometary comae, we find that the relative line fluxes in the 12"x9", 28" and
143" beams are consistent with expectations for a nuclear source of HCN and
expansion of the volatile gases and evaporating icy grains following a Haser
model.


title:
The Detection of Cold Dust in Cas A: Evidence for the Formation of
  Metallic Needles in the Ejecta

abstract:
  Recently, Dunne et al. (2003) obtained 450 and 850 micron SCUBA images of
CasA, and reported the detection of 2-4 M_sun of cold, 18K, dust in the
remnant. Here we show that their interpretation of the observations faces
serious difficulties. Their inferred dust mass is larger than the mass of
refractory material in the ejecta of a 10 to 30 M_sun star. The cold dust model
faces even more difficulties if the 170 micron observations of the remnant are
included in the analysis, decreasing the cold dust temperature to ~ 8K, and
increasing its mass to > 20 M_sun. We offer here a more plausible
interpretation of their observation, in which the cold dust emission is
generated by conducting needles with properties that are completely determined
by the combined submillimeter and X-ray observations of the remnant. The
needles consist of metallic whiskers with <1% of embedded impurities that may
have condensed out of blobs of material that were expelled at high velocities
from the inner metal-rich layers of the star in an asymmetric explosion. The
needles are collisionally heated by the shocked gas to a temperature of 8K.
Taking the destruction of needles into account, a dust mass of only 1E-4 to
1E-3M_sun is needed to account for the observed SCUBA emission. Aligned in the
magnetic field, needles may give rise to observable polarized emission. The
detection of submillimeter polarization will therefore offer definitive proof
for a needle origin for the cold dust emission. Supernovae may still be proven
to be important sources of interstellar dust, but the evidence is still
inconclusive.


title: The XMM-Newton view of radio-quiet and X-ray dim isolated neutron stars

abstract:
  (shortened) As part of the guaranteed time, guest observer and calibration
programs, XMM-Newton extensively observed a group of six thermally emitting,
isolated neutron stars which are neither connected with a supernova remnant nor
show pulsed radio emission. Four of the six sources are now well established as
X-ray pulsars: The 11.37 s period of RX J0806.4-4123 was confirmed in a second
XMM-Newton observation. In the case of the X-ray faintest of the six stars, RX
J0420.0-5022, the period marginally indicated in ROSAT data was not seen in the
EPIC data, instead a 3.45 s pulse period was clearly detected. Spectral
variations with pulse phase were discovered for the known 8.39 s pulsar RX
J0720.4-3125 and also RBS1223. For the latter EPIC data revealed a
double-peaked pulse profile for a neutron star spin period of 10.31 s. The
X-ray continuum spectra of all six objects are consistent with a Planckian
energy distribution with black-body temperatures kT between 40 eV and 100 eV.
EPIC data of the pulsars RBS1223 and RX J0720.4-3125 revealed a broad
absorption feature in their spectra at energies of 100-300 eV and ~260 eV,
respectively. The depth of this feature varies with pulse phase and may be
caused by cyclotron resonance scattering of protons or heavy ions in a strong
magnetic field. In such a picture the inferred field strength exceeds 10^13
Gauss, in the case of RX J0720.4-3125 consistent with the value estimated from
its pulse period derivative. A similar absorption feature in the RGS and EPIC
spectra of RX J1605.3+3249 was reported recently.


title:
A comparison of the time variation of radial abundance gradients from
  planetary nebulae and open clusters

abstract:
  The temporal behaviour of the radial abundance gradients has important
consequences on models for the chemical evolution of the Galaxy. We present a
comparison of the time variation of the abundance gradients in the Milky Way
disk as determined from a sample of planetary nebulae and open clusters. We
conclude that the [Fe/H] gradients as measured in open cluster stars strongly
support the time flattening of the abundance gradient as recently determined
from O/H measurements in planetary nebulae. We estimate the average flattening
rate in the time interval 10 Myr < t < 5 Gyr as roughly 0.005 dex kpc-1 Gyr-1.


title: The Liverpool Telescope Spectrograph: FRODOSpec

abstract:
  We describe in some detail one of the instruments that will be available in
2004 to the research community. FRODOSpec is an integral field unit
spectrograph that will be available for use with the 2 m robotic Liverpool
Telescope on the island of La Palma. We anticipate that this instrument will
open up major areas of research that cannot be carried out with conventionally
operated telescopes. Some of these research areas relate to indirect imaging of
astronomical objects like Doppler tomography and eclipse mapping.


title: A New, Simple Model for Black Hole High Frequency QPOs

abstract:
  Observations of X-ray emissions from binary systems have always been
considered important tools to test the validity of General Relativity in
strong-field regimes. The pairs and triplets of high frequency quasi-periodic
oscillations observed in binaries containing a black hole candidate, in
particular, have been proposed as a means to measure more directly the black
hole properties such as its mass and spin. Numerous models have been suggested
over the years to explain the QPOs and the rich phenomenology accompanying
them. Many of these models rest on a number of assumptions and are at times in
conflict with the most recent observations. We here propose a new, simple model
in which the QPOs result from basic p-mode oscillations of a non-Keplerian disc
of finite size. We show that within this new model all of the key properties of
the QPOs: a) harmonic ratios of frequencies even as the frequencies change; b)
variations in the relative strength of the frequencies with spectral energy
distribution and with photon energy; c) small and systematic changes in the
frequencies, can all be explained simply given a single reasonable assumption.


title: Neutrino-pasta scattering: the opacity of nonuniform neutron-rich matter

abstract:
  Neutron-rich matter at subnuclear densities may involve complex structures
displaying a variety of shapes, such as spherical, slablike, and/or rodlike
shapes. These phases of the {\it nuclear pasta} are expected to exist in the
crust of neutron stars and in core-collapse supernovae. The dynamics of
core-collapse supernovae is very sensitive to the interactions between
neutrinos and nucleons/nuclei. Indeed, neutrino excitation of the low-energy
modes of the pasta may allow for a significant energy transfer to the nuclear
medium, thereby reviving the stalled supernovae shock. The linear response of
the nuclear pasta to neutrinos is modeled via a simple semi-classical
simulation. The transport mean-free path for $\mu$ and $\tau$ neutrinos (and
antineutrinos) is expressed in terms of the static structure factor of the
pasta, which is evaluated using Metropolis Monte Carlo simulations.


title:
High temperature combustion: Approaching equilibrium using nuclear
  networks

abstract:
  A method for integrating the chemical equations associated with nuclear
combustion at high temperature is presented and extensively checked. Following
the idea of E. M\"uller, the feedback between nuclear rates and temperature was
taken into account by simultaneously computing molar fraction changes and
temperature response in the same matrix. The resulting algorithm is very stable
and efficient at calculating nuclear combustion in explosive scenarios,
especially in those situations where the reacting material manages to climb to
the nuclear statistical equilibrium regime. The numerical scheme may be useful
not only for those who carry out hydrodynamical simulations of explosive
events, but also as a tool to investigate the properties of a nuclear system
approaching equilibrium through a variety of thermodynamical trajectories.


title: Multi-Site observations of SU Aurigae

abstract:
  We present results from the 1996 MUSICOS (MUlti-SIte COntinuous Spectroscopy)
campaign on the T Tauri star SU Aurigae. We find a 2.7-d periodicity in the He
I (587.6 nm) line and somewhat longer, less well-pronounced periodicities in
the Balmer lines and in Na D. Our observations support the suggestion that the
wind and infall signatures are out of phase on SU Aur. We present Doppler
images of SU Aur that have been obtained from least-squares deconvolved
profiles. Images taken about one rotation apart show only limited overlap, in
particular at low latitudes. This is in part due to limitations in
signal-to-noise, and in part due to line profile deformations that arise from
short-lived and/or non-surface features. The agreement at high latitudes is
better and suggests that at least some longer-lived features are present. The
analysis of Stokes V profiles yields a marginal magnetic field detection during
one of the phases.


title: Jet evolution, flux ratios and light-travel time effects

abstract:
  Studies of the knotty jets in both quasars and microquasars frequently make
use of the ratio of the intensities of corresponding knots on opposite sides of
the nucleus in order to infer the product of the intrinsic jet speed (beta) and
the cosine of the inclination angle of the jet-axis (cos{theta}), via the
formalism
  I_{a}/I_{r} = ((1+beta cos{theta})/(1-beta cos{theta}))^{3+alpha}, where
alpha relates the intensity I_{nu} as a function of frequency nu as I_{nu}
propto nu^{-alpha}. Where beta cos{theta} is determined independently, the
intensity ratio of a given pair of jet to counter-jet knots is over-predicted
by the above formalism compared with the intensity ratio actually measured from
radio images. As an example in the case of Cygnus X-3 the original formalism
predicts an intensity ratio of about 185, whereas the observed intensity ratio
at one single epoch is about 3. Mirabel and Rodriguez (1999) have refined the
original formalism, and suggested measuring the intensity ratio of knots when
they are at equal angular separations from the nucleus. This method is only
applicable where there is sufficient time-sampling with sufficient physical
resolution to interpolate the intensities of the knots at equal distances from
the nucleus, and can therefore be difficult to apply to microquasars and is
impossible to apply to quasars. Accounting for both the light-travel time
between the knots and the simple evolution of the knots themselves reconciles
this over-prediction and renders the original formalism obsolete.


title:
The Influence of Quark Matter at High Densities on Binary Neutron Star
  Mergers

abstract:
  We consider the influence of potential quark matter existing at high
densities in neutron star interiors on gravitational waves (GW) emitted in a
binary neutron star merger event. Two types of equations of state (EoS) at zero
temperatures are used, one describing pure nuclear matter, the other nuclear
matter with a phase transition to quark matter at very high densities. Binary
equilibrium sequences close to the innermost stable circular orbit (ISCO) are
calculated to determine the GW frequencies just before merger. It is found that
EoS effects begin to play a role for gravitational masses larger than
$M_\infty\simeq1.5M_\odot$. The difference in the gravitational wave frequency
at the ISCO grows to up to $\simeq 10%$ for the maximal allowed mass given by
the EoSs used. Then, we perform 3D hydrodynamic simulations for each EoS
varying the initial mass and determine the characteristic GW frequencies of the
merger remnants. The implications of quark matter show up mainly in a different
collapse behaviour of the merger remnant. If the collapse does not take place
immediately after merger, we find a phase difference between two EoS's in the
post-merger GW signal. We also compare the GW frequencies emitted by the merger
remnant to values from simulations using a polytropic EoS and find an imprint
of the non-constant adiabatic index of our EoSs. All calculations are based on
the conformally flat (CF) approximation to general relativity and the GW signal
from the merger simulation is extracted up to quadrupole order.


title:
Ultra-High Energy Cosmic Ray Probes of Large Scale Structure and
  Magnetic Fields

abstract:
  We study signatures of a structured universe in the multi-pole moments,
auto-correlation function, and cluster statistics of ultra-high energy cosmic
rays above 10^19 eV. We compare scenarios where the sources are distributed
homogeneously or according to the baryon density distribution obtained from a
cosmological large scale structure simulation. The influence of extragalactic
magnetic fields is studied by comparing the case of negligible fields with
fields expected to be produced along large scale shocks with a maximal strength
consistent with observations. We confirm that strongly magnetized observers
would predict considerable anisotropy on large scales, which is already in
conflict with current data. In the best fit scenario only the sources are
strongly magnetized, although deflection can still be considerable, of order 20
degrees up to 10^20 eV, and a pronounced GZK cutoff is predicted. We then
discuss signatures for future large scale full-sky detectors such as the Pierre
Auger and EUSO projects. Auto-correlations are sensitive to the source density
only if magnetic fields do not significantly affect propagation. In contrast,
for a weakly magnetized observer, degree scale auto-correlations below a
certain level indicate magnetized discrete sources. It may be difficult even
for next generation experiments to distinguish between structured and
unstructured source distributions.


title: A Photometric Study of Stars in the MBM 12 Association

abstract:
  We have monitored four fields containing nine previously identified members
of the MBM 12 association to search for photometric variability and periodicity
in these pre-main sequence stars. Seven of the nine are found to be variable
and definite periodicity (of 1.2, 2.6 and 6.2 days) is found for three of them,
including the classical T Tauri star LkH-alpha 264. Two other members are
possibly periodic but each requires confirmation. In addition, a "field" star
that is associated with the X-ray source RX J0255.9+2005 was discovered to be a
variable with a period of 4.2 days. Our results indicate that the photometric
variability characteristics of the known MBM 12 association members are typical
of what is found in ~few My old stellar groups such as IC 348, supporting
arguments for a similar age. In particular, there is a mix of periodic and
non-periodic variables with typical amplitudes (in Cousins I) of 0.1-0.5 mag,
in addition to a small number of larger amplitude variables. The periods, as a
group, are somewhat shorter than in IC 348 but when allowance is made for the
known dependence of period on mass in pre-main sequence stars the difference
may not be significant. Our data confirm and illustrate the value of
photometric monitoring as a tool for identifying likely association members and
for studying rotation in extremely young stellar groups.


title:
A Double-Pulsar System - A Rare Laboratory for Relativistic Gravity and
  Plasma Physics

abstract:
  The clock-like properties of pulsars moving in the gravitational fields of
their unseen neutron-star companions have allowed unique tests of general
relativity and provided evidence for gravitational radiation. We report here
the detection of the 2.8-sec pulsar J0737-3039B as the companion to the 23-ms
pulsar J0737-3039A in a highly-relativistic double-neutron-star system,
allowing unprecedented tests of fundamental gravitational physics. We observe a
short eclipse of J0737-3039A by J0737-3039B and orbital modulation of the flux
density and pulse shape of J0737-3039B, probably due to the influence of
J0737-3039A's energy flux upon its magnetosphere. These effects will allow us
to probe magneto-ionic properties of a pulsar magnetosphere.


title: Quasar Feedback: the Missing Link in Structure Formation

abstract:
  We consider the impact of quasar outflows on structure formation. Such
outflows are potentially more important than galactic winds, which appear
insufficient to produce the level of preheating inferred from X-ray
observations of galaxy clusters. Using a simple analytical model for the
distribution of quasars with redshift, coupled with a one-dimensional
Sedov-Taylor model for outflows, we are able to make robust statements about
their impact of on structure formation. As large regions of the IGM are heated
above a critical entropy of approximately 100 keV cm^2, cooling become
impossible within them, regardless of changes in density. On quasar scales,
this has the effect of inhibiting further formation, resulting in the observed
fall-off in their number densities below z = 2. On galaxy scales, quasar
feedback fixes the turn-over scale in the galaxy luminosity function (L_*) as
the nonlinear scale at the redshift of strong feedback. The galaxy luminosity
function then remains largely fixed after this epoch, consistent with recent
observations and in contrast to the strong evolution predicted in more standard
galaxy-formation models. Finally, strong quasar feedback explains why the
intracluster medium is observed to have been pre-heated to entropy levels just
above S_crit, the minimum excess that would not have been erased by cooling.
The presence of such outflows is completely consistent with the observed
properties of the Lyman-alpha forest at z ~ 2, but is expected to have a
substantial and detectable impact on Compton distortions observed in the
microwave background and the multiphase properties of the "warm-hot" (z=0)
circumgalactic medium.


title:
The tumultuous lives of galactic dwarfs and the missing satellites
  problem

abstract:
  Hierarchical Cold Dark Matter (CDM) models predict that Milky Way (MW) sized
halos contain hundreds of dense low-mass dark satellites, an order of magnitude
more than the number of observed satellites in the Local Group (LG). If the CDM
paradigm is correct, we need to understand why most of these halos failed to
form stars and become galaxies. We analyze the dynamical evolution of the
satellite halos in a high-resolution cosmological simulation of MW sized halos
in the LCDM cosmology. We find that about 10% of the substructure halos with
the present masses <10^8-10^9 Msun (circular velocities Vmax<30 km/s) had
considerably larger masses and circular velocities when they formed at
redshifts z>2. After the initial period of mass accretion in isolation, these
objects experience dramatic mass loss due to tidal stripping, in some cases
even before they are accreted by their host halo. This can explain how the
smallest dwarf spheroidal galaxies of the LG were able to build up a sizable
stellar mass in their seemingly shallow potential wells. We propose a new model
in which all of the luminous dwarf spheroidals in the Local Group are
descendants of the relatively massive (>10^9 Msun) high-redshift systems, in
which the gas could cool efficiently by atomic line emission and which were not
significantly affected by the extragalactic ultraviolet radiation. We present a
simple galaxy formation model based on the trajectories extracted from the
simulation, which accounts for the bursts of star formation after strong tidal
shocks and the inefficiency of gas cooling in halos with virial temperatures
Tvir<~10^4 K. Our model reproduces the abundance, spatial distribution, and
morphological segregation of the observed Galactic satellites. The results are
insensitive to the redshift of reionization.


title: Effects of halo substructure on the power spectrum and bispectrum

abstract:
  We study the effects of halo substructure and a distribution in the
concentration parameter of haloes on large-scale structure statistics. The
effects on the power spectrum and bispectrum are studied on the smallest scales
accessible from future surveys. We compare halo-model predictions with results
based on N-body simulations, but also extend our predictions to 10-kpc scales
which will be probed by future simulations. We find that weak-lensing surveys
proposed for the coming decade can probe the power spectrum on small enough
scales to detect substructure in massive haloes. We discuss the prospects of
constraining the mass fraction in substructure in view of partial degeneracies
with parameters such as the tilt and running of the primordial power spectrum.


title: The massive binary companion star to the progenitor of supernova 1993J

abstract:
  The massive star which underwent core-collapse to produce SN1993J was
identified as a non-variable red supergiant star in images of the galaxy M81
taken before explosion. However the stellar source showed an excess in UV and
B-band colours that suggested it had either a hot, massive companion star or
was embedded in an unresolved young stellar association. The spectra of SN1993J
underwent a remarkable transformation between a hydrogen-rich Type II supernova
and a helium-rich (hydrogen-deficient) Type Ib. The spectral and photometric
peculiarities were explained by models in which the 13-20 solar mass supergiant
had lost almost its entire hydrogen envelope to a close binary companion. The
binary scenario is currently the best fitting model for the production of such
type IIb supernovae, however the hypothetical massive companion stars have so
far eluded discovery. Here we report the results of new photometric and
spectroscopic observations of SN1993J, 10 years after explosion. At the
position of the fading SN we detect the unambiguous signature of a massive
star, the binary companion to the progenitor. This is evidence that this type
of SN originate in interacting binary systems.


title:
Primordial Nucleosynthesis for the New Cosmology: Determining
  Uncertainties and Examining Concordance

abstract:
  Big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) have
a long history together in the standard cosmology. The general concordance
between the predicted and observed light element abundances provides a direct
probe of the universal baryon density. Recent CMB anisotropy measurements,
particularly the observations performed by the WMAP satellite, examine this
concordance by independently measuring the cosmic baryon density. Key to this
test of concordance is a quantitative understanding of the uncertainties in the
BBN light element abundance predictions. These uncertainties are dominated by
systematic errors in nuclear cross sections. We critically analyze the cross
section data, producing representations that describe this data and its
uncertainties, taking into account the correlations among data, and explicitly
treating the systematic errors between data sets. Using these updated nuclear
inputs, we compute the new BBN abundance predictions, and quantitatively
examine their concordance with observations. Depending on what deuterium
observations are adopted, one gets the following constraints on the baryon
density: OmegaBh^2=0.0229\pm0.0013 or OmegaBh^2 = 0.0216^{+0.0020}_{-0.0021} at
68% confidence, fixing N_{\nu,eff}=3.0. Concerns over systematics in helium and
lithium observations limit the confidence constraints based on this data
provide. With new nuclear cross section data, light element abundance
observations and the ever increasing resolution of the CMB anisotropy, tighter
constraints can be placed on nuclear and particle astrophysics. ABRIDGED


title: The Andromeda Stream

abstract:
  The existence of a stream of tidally stripped stars from the Sagittarius
Dwarf galaxy demonstrates that the Milky Way is still in the process of
accreting mass. More recently, an extensive stream of stars has been uncovered
in the halo of the Andromeda galaxy (M31), revealing that it too is
cannibalizing a small companion. This paper reports the recent observations of
this stream, determining it spatial and kinematic properties, and tracing its
three-dimensional structure, as well as describing future observations and what
we may learn about the Andromeda galaxy from this giant tidal stream.