title: Magnetic Field Geometry of the Broad Line Radio Galaxy 3C111

abstract:
  Very Long Baseline Polarimetric observations of the Broad Line Radio galaxy
3C111 performed in July and September of 1996 at 8 and 43 GHz reveal rapidly
evolving parsec-scale radio structure after a large millimetre outburst. The
B-field geometry is not simple. We present a first analysis of possible Faraday
and optical depth effects based on a comparison of the polarization images for
the two frequencies.


title: Pc-scale study of Radio galaxies & BL Lacs

abstract:
  We study two aspects of the differences between Active Galactic Nuclei (AGN)
of the two Fanaroff-Riley types in order to investigate the causes of the F-R
divide. We (a) contrast the properties of the optical cores in beamed and
unbeamed AGN of the two types, incorporating Hubble Space Telescope
measurements of the unbeamed objects, and (b) contrast the nuclear magnetic
field geometry of the beamed AGN of the two types using Very Long Baseline
Polarimetry.


title:
One Ring to Encompass them All: A giant stellar structure that surrounds
  the Galaxy

abstract:
  We present evidence that the curious stellar population found by the Sloan
Digital Sky Survey in the Galactic anticentre direction extends to other
distant fields that skirt the plane of the Milky Way. New data, taken with the
INT Wide Field Camera show a similar population, narrowly aligned along the
line of sight, but with a Galactocentric distance that changes from ~15 kpc to
\~20 kpc (over ~100 degrees on the sky). Despite being narrowly concentrated
along the line of sight, the structure is fairly extended vertically out of the
plane of the Disk, with a vertical scale height of 0.75+/-0.04 kpc. This
finding suggests that the outer rim of the Galaxy ends in a low-surface
brightness stellar ring. Presently available data do not allow us to ascertain
the origin of the structure. One possibility is that it is the wraith of a
satellite galaxy devoured long-ago by the Milky Way, though our favoured
interpretation is that it is a perturbation of the disk, possibly the result of
ancient warps. Assuming that the Ring is smooth and axisymmetric, the total
stellar mass in the structure may amount to 2x10^8 up to 10^9 Solar masses.


title: Magnetic Field Geometry in "Red" and "Blue" BL Lacs

abstract:
  We compare the systematics of the magnetic field geometry in the "red"
low-energy peaked BL Lacs (LBLs) and "blue" high-energy peaked BL Lacs (HBLs)
using VLBI polarimetric images. The LBLs are primarily "radio--selected" BL
Lacs and the HBLs are primarily "X-ray selected". In contrast to the LBLs,
which show predominantly transverse jet magnetic fields, the HBLs show
predominantly longitudinal fields. Thus, while the SED peaks of core-dominated
quasars, LBLs and HBLs form a sequence of increasing frequency, the magnetic
field geometry does not follow an analogous sequence. We briefly investigate
possible connections between the observed parsec-scale magnetic field
structures and circular polarization measurements in the literature on various
spatial scales.


title: Jeans solutions for triaxial galaxies

abstract:
  The Jeans equations relate the second-order velocity moments to the density
and potential of a stellar system. For general three-dimensional stellar
systems, there are three equations, but these are not very helpful, as they
contain six independent moments. By assuming that the potential is triaxial and
of separable Staeckel form, the mixed moments vanish in confocal ellipsoidal
coordinates. The three Jeans equations and three remaining non-vanishing
moments form a closed system of three highly-symmetric coupled first-order
partial differential equations in three variables. They were first derived by
Lynden-Bell in 1960, but have resisted solution by standard methods. Here we
present the general solution by superposition of singular solutions.


title: A SAURON view of galaxies

abstract:
  We have measured the two-dimensional kinematics and line-strength
distributions of 72 representative nearby early-type galaxies, out to
approximately one effective radius, with our panoramic integral-field
spectrograph SAURON. The resulting maps reveal a rich variety in kinematical
structures and linestrength distributions, indicating that early-type galaxies
are more complex systems than often assumed. We are building detailed dynamical
models for these galaxies, to derive their intrinsic shape and dynamical
structure, and to determine the mass of the supermassive central black hole.
Here we focus on two examples, the compact elliptical M32 and the E3 galaxy
NGC4365. These objects represent two extreme cases: M32 has very regular
kinematics which can be represented accurately by an axisymmetric model in
which all stars rotate around the short axis, while NGC4365 is a triaxial
galaxy with a prominent kinematically decoupled core, with an inner core that
rotates about an axis that is nearly perpendicular to the rotation axis of the
main body of the galaxy. Our dynamical models for these objects demonstrate
that two-dimensional observations are essential for deriving the intrinsic
orbital structure and dark matter content of galaxies.


title:
Accelerated expansion of the Crab Nebula and evaluation of its
  neutron-star parameters

abstract:
  A model of an accelerated expansion of the Crab Nebula powered by the
spinning-down Crab pulsar is proposed, in which time dependence of the
acceleration is connected with evolution of pulsar luminosity. Using recent
observational data, we derive estimates of the Crab neutron-star moment of
inertia. Correlations between the neutron star moment of inertia and its mass
and radius allow for rough estimates of the Crab neutron-star radius and mass.
In contrast to the previously used constant-acceleration approximation, even
for the expanding nebula mass ~7 M_sun results obtained within our model do not
stay in conflict with the modern stiff equations of state of dense matter.


title: NGC 4608 and NGC 5701: Barred Galaxies without Disks?

abstract:
  We have performed for the first time in the literature a 2D structural
analysis on the barred lenticular and face--on galaxies NGC 4608 and NGC 5701.
The results indicate that these galaxies either have never had large disks or
their disks were almost completely destroyed by their strong bars, due to
secular evolution processes. We discuss these surprising conclusions checking
for signs of secular evolution, considering bar forming instabilities, and
suggesting, based on N-body simulations, a new mechanism to form bars in
spheroids, which includes non-spherical halos. Quantitative predictions from
our new mechanism are compared with those from other recent models for bar
formation and evolution.


title: Equation of state of dense matter and maximum mass of neutron stars

abstract:
  Theoretical models of the equation of state (EOS) of neutron-star matter
(starting with the crust and ending at the densest region of the stellar core)
are reviewed. Apart from a broad set of baryonic EOSs, strange quark matter,
and even more exotic (abnormal and Q-matter) EOSs are considered. Results of
calculations of M_max for non-rotating neutron stars and exotic compact stars
are reviewed, with particular emphasis on the dependence on the dense-matter
EOS. Rapid rotation increases M_max, and this effect is studied for both
neutron stars and exotic stars. Theoretical results are then confronted with
measurements of masses of neutron stars in binaries, and the consequences of
such a confrontation and their possible impact on the theory of dense matter
are discussed.


title: Microlensing by free-floating brown dwarfs

abstract:
  We propose a near-infrared microlensing survey of the central 2 degree field
of the Galactic Center, in an attempt to estimate the surface density and mass
distribution of distant free-floating brown dwarfs in the bulge and in the
disk, acting as lenses of bright stars towards the Galactic Center. We estimate
the probability (optical depth) of microlensing events to be 10^{-7} and the
typical timescale (full-width) of the amplification lightcurve to be about 1
week. The necessary wide-field NIR survey technology should soon be available
on UKIRT, CFHT, and with VISTA at ESO/Paranal.


title: Gas Kinematics of Three Hickson Compact Groups: The Data

abstract:
  We present Fabry Perot observations of three Hickson Compact Groups, HCG 88,
HCG 89 and HCG 100. We detect ionized gas in 15 group members, three of which
were previously uncatalogued objects, two in HCG 89 and one in HCG 100. We were
able to derive 2D velocity, monochromatic and continuum maps and rotation
curves for a total of 12 giant late-type galaxies and two dwarf galaxies. Even
with this small sample of three groups, we can clearly see a trend of kinematic
evolution and the different evolutionary stages of the groups. The members of
HCG 88 show almost no signs of previous or current interactions, while HCG 100
contains at least two merging and one strongly-interacting galaxies. HCG 89
shows members with signs of interactions and galaxies with normal kinematics.
We therefore classify HCG 88, HCG 89 and HCG 100 respectively as an unevolved
group, a mildly interacting group and a system in the final stage of evolution.


title: On the accretion luminosity of isolated neutron stars

abstract:
  The accretion process onto a magnetized isolated neutron star, which captures
material from the interstellar medium, is discussed. The evolutionary track of
such a star can be presented as a sequence of four states: ejector, supersonic
propeller, subsonic propeller, and steady accretor. I show that subsonic
propeller - accretor transition does not occur as long as the magnetic field of
the star is strong enough to control the accretion flow in the stellar
vicinity. During the subsonic propeller state the accretion rate onto the
stellar surface is limited to the rate of plasma diffusion into its
magnetosphere. The diffusion rate is at least three orders of magnitude smaller
than the maximum possible mass capture rate by the star. Therefore, the
expected accretion luminosity of magnetized isolated neutron stars is at least
three orders of magnitude smaller than that previously evaluated.


title:
Determining Foreground Contamination in CMB Observations: Diffuse
  Galactic Emission in the MAXIMA-I Field

abstract:
  Observations of the CMB can be contaminated by diffuse foreground emission
from sources such as Galactic dust and synchrotron radiation. In these cases,
the morphology of the contaminating source is known from observations at
different frequencies, but not its amplitude at the frequency of interest for
the CMB. We develop a technique for accounting for the effects of such emission
in this case, and for simultaneously estimating the foreground amplitude in the
CMB observations. We apply the technique to CMB data from the MAXIMA-1
experiment, using maps of Galactic dust emission from combinations of IRAS and
DIRBE observations, as well as compilations of Galactic synchrotron emission
observations. The spectrum of the dust emission over the 150--450 GHz observed
by MAXIMA is consistent with preferred models but the effect on CMB power
spectrum observations is negligible.


title: Formation of massive binaries

abstract:
  The formation of massive stars is one of the major unsolved problems in
stellar astrophysics. However, only few if any of these are found as single
stars, on average massive stars have more than one companion. Many of them are
born in dense stellar clusters and several clusters have an excess of massive
short-period spectroscopic binaries, with severe implication for binary-related
stellar evolution including mergers, and also for the origin of massive runaway
stars. The multiplicity of massive stars seems to increase with increasing
primary mass and with increasing density of young star clusters. These
observations suggest that massive binary and multiple systems originate mainly
from dynamical gravitational interactions and accretion-induced protostellar
collisions in dense clusters. If true, the binary properties of massive stars
in less dense OB associations should be less extreme. This prediction should be
tested by future observations.The paper reviews both the latest observations
and theoretical ideas related to the origin of massive binaries. It concludes
with a speculation on how the binary properties might change with metallicity
(e.g. LMC/SMC).


title: Integral Field Spectroscopy of SN 2002er with PMAS

abstract:
  We present observations of the Type Ia supernova SN 2002er during the
brightening phase. The observations were performed with the Potsdam Multi
Aperture Spectrophotometer (PMAS) integral field instrument. Due to the 8"*8",
field of view of the spectrograph an accurate background subtraction was
possible. Results from analyses of the evolution of absorption features in
comparisons with other SNe show that SN 2002er is a fairly bright Type Ia
supernova with a peak brightness of M_B=-19.6+-0.1.


title: Chances for earth-like planets and life around metal-poor stars

abstract:
  We discuss the difficulties of forming earth-like planets in metal-poor
environments, such as those prevailing in the Galactic halo (Pop II), the
Magellanic Clouds, and the early universe. We suggest that, with less heavy
elements available, terrestrial planets will be smaller size and lower mass
than in our solar system (solar metallicity). Such planets may not be able to
sustain life as we know it. Therefore, the chances of very old lifeforms in the
universe are slim, and a threshold metallicty (1/2 solar?) may exist for life
to originate on large enough earth-like planets.


title: Near-infrared Spectra of Chamaeleon I Stars

abstract:
  We present low resolution (R = 500) near-infrared spectra of 46 candidate
young stellar objects in the Chamaeleon I star-forming region recently detected
in several deep photometric surveys of the cloud. Most of these stars have K <
12. In addition, we present spectra of 63 previously known southern hemisphere
young stars mainly belonging to the Chamaeleon I and Lupus dark clouds. We
describe near-infrared spectroscopic characteristics of these stars and use the
water vapor indexes to derive spectral types for the new objects. Photometric
data from the literature are used to estimate the bolometric luminosities of
all sources. We apply D'Antona & Mazzitelli (1998) pre-main sequence
evolutionary tracks and isocrones to derive masses and ages. We detect two
objects with mass below the H burning limit among the 46 new candidates. One of
this object (PMK99 IR Cha INa1) is the likely driving source of a bipolar
outflow in the northern region of the cloud.


title: Large Scale Mapping of the $\rho$ Ophiuchi Regions by SWAS

abstract:
  We have completed a 3 square degree CI $^3$P$_1$-$^3$P$_0$ map of the \r\
Ophiuchi regions using SWAS. The remarkably stable receiver and backends
systems of SWAS allow for uniformly calibrated data set on this scale. Combined
with \co, \13co, and \c18o maps made using FCRAO, this data set will facilitate
a thorough study of the physics and the chemistry in this nearby star forming
region.


title: The power spectrum of galaxy clustering in the APM survey

abstract:
  We measure the power spectrum of galaxy clustering in real space from the APM
Galaxy Survey. We present an improved technique for the numerical inversion of
Limber's equation that relates the angular clustering of galaxies to an
integral over the power spectrum in three dimensions. Our approach is
underpinned by a large ensemble of mock galaxy catalogues constructed from the
Hubble Volume N-body simulations. The mock catalogues are used to test for
systematic effects in the inversion algorithm and to estimate the errors on our
measurement. We find that we can recover the power spectrum to an accuracy of
better than 15% over three decades in wavenumber. A key advantage of the use of
mock catalogues to infer errors is that we can apply our technique on scales
for which the density fluctuations are not Gaussian, thus probing the regime
that offers the best constraints on models of galaxy formation. On large
scales, our measurement of the power spectrum is consistent with the shape of
the mass power spectrum in the popular ``concordance'' cold dark matter model.
The galaxy power spectrum on small scales is strongly affected by nonlinear
evolution of density fluctuations, and, to a lesser degree, by galaxy bias. The
rms variance in the galaxy distribution, when smoothed in spheres of radius 8
h^(-1)Mpc, is sigma^g_8=0.96^(+0.17)_(-0.20) and the shape of the power
spectrum on large scales is described by a simple fitting formula with
parameter Gamma= 0.19^(+0.13)_(-0.04) (these errors are the 1-sigma ranges for
a two parameter fit). We use our measurement of the power spectrum to estimate
the galaxy two point correlation function; the results are well described by a
power law with correlation length r_0 = 5.9 +- 0.7 h^(-1)Mpc and slope gamma =
1.61 +- 0.06 for pair separations in the range 0.1 < r/[h^(-1)Mpc] < 20.


title: Lyman Break Galaxies at z~5: Luminosity Function

abstract:
  (abridged) We present results of a search for Lyman break galaxies (LBGs) at
z ~ 5 in a 618 square-arcmin field including the HDF-N taken by Subaru Prime
Focus Camera. Utilizing the published redshift data of the HDF-N and its
flanking fields, the color selection criteria are chosen so that LBGs are
picked out most efficiently and least contaminated by foreground objects. The
numbers of LBG candidates detected are 310 in 23.0 < I_c < 25.5. The rest-frame
UV luminosity function(LF) of LBGs at z ~ 5 is derived statistically. The
fraction of contamination is estimated to be ~50% in the faintest magnitude
range. The completeness of the survey is ~80% at the bright part of the sample,
and ~20% in the faintest magnitude range (25.0 < I_c <= 25.5). The LF of LBG
candidates at z ~ 5 does not show a significant difference from those at z ~ 3
and 4, though there might be a slight decrease in the fainter part. The UV
luminosity density within the observational limit is 0.56 - 0.69 times smaller
than that obtained for LBGs at z ~ 3, depending on the adopted cosmology and
the integration range of the LF. The similarity of the LFs at redshifts 5 to 3
implies that most of LBGs at z ~ 5 should have faded out at z ~ 3 and LBGs at z
\~ 5 are different galaxies from those seen at z ~ 3, if we take face values
for ages of the LBGs at z ~ 3 obtained by the SED fitting in which a continuous
star formation in an individual galaxy is assumed. However, if the star
formation in LBGs is sporadic, the similarity of the LF at z ~ 3 and 5 would be
explained. Such sporadic star formation has been suggested by hydrodynamical
simulations and semi-analytic models with collisional starbursts, and the trend
of the cosmic star formation history predicted by these studies resembles to
that estimated from the UV luminosity density within the observational limit.


title: An Alternative to the Variation of the Fine Structure Constant

abstract:
  It is considered that quasars evolve into normal galaxies by means of
expansion of matter. The order of magnitude of the expansion velocity can be
estimated. The Doppler shift caused by such expansion explains the supposed
variation of the fine structure constant. This variation has been based on
observations of absorption lines of gas clouds seen against background quasars.
These ideas maintain the constancy of the fine structure constant.


title: The Extended Tidal Tails of Palomar 5: Tracers of the Galactic Potential

abstract:
  We detected extended, curved stellar tidal tails emanating from the sparse,
disrupting halo globular cluster Pal 5, which cover 10 degrees on the sky.
These streams allow us to infer the orbit of Pal 5 and to ultimately constrain
the Galactic potential at its location.


title: Dark Energy and the Fate of the Universe

abstract:
  It is often assumed that in the course of the evolution of the universe, the
dark energy either vanishes or becomes a positive constant. However, recently
it was shown that in many models based on supergravity, the dark energy
eventually becomes negative and the universe collapses within the time
comparable to the present age of the universe. We will show that this
conclusion is not limited to the models based on supergravity: In many models
describing the present stage of acceleration of the universe, the dark energy
eventually becomes negative, which triggers the collapse of the universe within
the time t = 10^10-10^11 years. The theories of this type have certain
distinguishing features that can be tested by cosmological observations.


title: Formation of giant planets by fragmentation of protoplanetary disks

abstract:
  The evolution of gravitationally unstable protoplanetary gaseous disks has
been studied with the use of three-dimensional smoothed particle hydrodynamics
simulations with unprecedented resolution. We have considered disks with
initial masses and temperature profiles consistent with those inferred for the
protosolar nebula and for other protoplanetary disks. We show that
long-lasting, self-gravitating protoplanets arise after a few disk orbital
periods if cooling is efficient enough to maintain the temperature close to 50
K. The resulting bodies have masses and orbital eccentricities similar to those
of detected extrasolar planets.


title: Search for and study of extremely metal-deficient galaxies

abstract:
  We summarize the progress in identifying and observational study of extremely
metal-deficient (XMD) gas-rich galaxies (BCGs, dIr and LSBDs). Due to volume
limitations only following issues are addressed: sample creation, some
statistical data, Colour-Magnitude Diagrams (CMD) and ages, the case of SBS
0335--052 system, and probable evolution paths of various XMD objects.


title:
Phase Coherent Timing of PSR J1811-1925: The Pulsar at the Heart of
  G11.2-0.3

abstract:
  The X-ray Pulsar PSR J1811-1925 in the historic supernova remnant G11.2-0.3
has a characteristic age over 10 times the age of the remnant. This likely
implies that its current spin period, 65 ms, is close to its birth spin period.
Alternatively, the pulsar may have an unusually high braking index. We report
here on regular Rossi X-ray Timing Explorer/ Proportional Counting Array
(RXTE/PCA) timing observations of the pulsar that were designed to measure its
braking index. We provide a preliminary phase-coherent timing solution which
includes a significant $\ddot{\nu}$. The braking index we measure is >> 3,
likely a result of conventional timing noise. We also report on a preliminary
analysis of the pulsar's unusually hard spectrum: we determine a photon index
of $\Gamma = 1.78\pm0.74$, for the pulsed component of the spectra, consistent
within the uncertainties with previous ASCA and Chandra observations. The
pulsed emission of PSR J1811-1925 is seen beyond 30 keV, and the pulsations
remain sinusoidal up to and beyond this energy.


title: Spectral Fits to the 1999 Aql X-1 Outburst Data

abstract:
  We present analysis and spectral fits of the RXTE data from the May/June 1999
outburst of Aql X-1. These data include observations in the rising portion of
the hard state, in the soft state, and in the falling portion of the hard
state. We show that the data can be fit by a purely thermal Comptonization
model for all the observations, but that more complicated models cannot be
ruled out. Up to 60% of the corona's power in the soft state may be injected
into non-thermal electrons. The soft state data show approximately constant
optical depth and coronal temperatures over a range of $\sim10$ in luminosity,
while they show evidence for a reduction of seed photon temperature with
reduced luminosity and indicate that the characteristic size of the seed photon
emitting region is roughly constant throughout the soft state. The hard state
before the soft state shows a higher luminosity, higher optical depth, and
lower electron temperature than the hard state after the soft state. We find a
reduction of the hard (30-60 keV) X-ray flux during a type I burst and show
that it requires a total corona energy reservoir of less than $\sim 10^{38}$
ergs.


title:
Anomalous X-ray Pulsars: Long-Term Monitoring and Soft-Gamma Repeater
  like X-ray Bursts

abstract:
  We report on long-term monitoring of anomalous X-ray pulsars (AXPs) using the
Rossi X-ray Timing Explorer (RXTE). Using phase-coherent timing, we find a wide
variety of behaviors among the sources, ranging from high stability (in 1E
2259.1+586 in quiescence and 4U 0142+61), to instabilities so severe that
phase-coherent timing is not possible (in 1E 1048.1-5937). We note a
correlation in which timing stability in AXPs decreases with increasing
$\dot{\nu}$. The timing stability of soft gamma repeaters (SGRs) in quiescence
is consistent with this trend, which is similar to one seen in radio pulsars.
We find no significant pulse morphology variations in any AXP in quiescence. We
considered high signal-to-noise average pulse profiles for each AXP as a
function of energy. We show that, as in the timing properties, there is a
variety of different behaviors for the energy dependence. We also used the
monitoring and archival data to obtain pulsed flux time series for each source.
We have found no large changes in pulsed flux for any source in quiescence, and
have set $1\sigma$ upper limits on variations ~20-30% depending on the source.
We have recently discovered bursts from the direction of two AXPs: 1E
1048.1-5937 the most SGR-like AXP, and 1E 2259.1+586 the most rotationally
stable AXP. We compare the temporal, spectral and flux properties of these
events to those of SGR bursts, and show that the two phenomena are very
similar. These results imply a close relationship between AXPs and SGRs, with
both being magnetars.


title: Control of star formation by supersonic turbulence

abstract:
  Understanding the formation of stars in galaxies is central to much of modern
astrophysics. For several decades it has been thought that stellar birth is
primarily controlled by the interplay between gravity and magnetostatic
support, modulated by ambipolar diffusion. Recently, however, both
observational and numerical work has begun to suggest that support by
supersonic turbulence rather than magnetic fields controls star formation. In
this review we outline a new theory of star formation relying on the control by
turbulence. We demonstrate that although supersonic turbulence can provide
global support, it nevertheless produces density enhancements that allow local
collapse. Inefficient, isolated star formation is a hallmark of turbulent
support, while efficient, clustered star formation occurs in its absence. The
consequences of this theory are then explored for both local star formation and
galactic scale star formation. (ABSTRACT ABBREVIATED)


title: Radio Galaxies and the Magnetization of the IGM

abstract:
  Observed radio galaxies had a much higher comoving density during the `quasar
era', at z ~ 2-3, but these sources are only detectable for small fractions of
their active lifetimes at such high z due to expansion losses and increased
inverse Compton losses against the cosmic microwave background. Using recent
models for the evolution of the size and luminosity of powerful double radio
sources, as well as LCDM simulations of the cosmic web of baryonic material, we
argue that during the quasar era a high volume fraction of this web was
occupied by the lobes of double radio sources. They could have seeded the IGM
with an average magnetic field approaching 10^{-8} G. Further, these advancing
overpressured lobes could compress the denser interstellar gas clouds of the
galaxies engulfed by them and thus trigger starbursts. This can probably
account for much of the intense star-formation activity witnessed beyond z ~
1.5. Also, the sweeping up of the ISM of the gas-rich galaxies by the rapidly
advancing radio lobes may well be responsible for the widespread metal
pollution of the IGM and proto-galaxies at high redshifts.


title:
Detection of Nine M8.0-L0.5 Binaries: The Very Low Mass Binary
  Population and its Implications for Brown Dwarf and VLM Star Formation

abstract:
  Use of the highly sensitive Hokupa'a/Gemini curvature wavefront sensor has
allowed direct adaptive optics (AO) guiding on very low mass (VLM) stars with
SpT=M8.0-L0.5. A survey of 39 such objects detected 9 VLM binaries. Most of
these systems are tight (separation <5 AU) and have similar masses (Delta
Ks<0.8 mag; 0.85<q<1.0). We find a sensitivity corrected binary fraction in the
range 15+/-7% for M8.0-L0.5 stars with separations >2.6 AU. This is slightly
less than the 32+/-9% measured for more massive M0-M4 dwarfs over the same
separation range (Fischer & Marcy 1992). It appears M8.0-L0.5 binaries (as well
as L and T dwarf binaries) have a much smaller semi-major axis distribution
peak (~4 AU) than early M binaries. We also find no VLM binary systems (defined
here as systems with M_tot<0.185 solar masses) with separations >15 AU.
  We briefly explore possible reasons why VLM binaries are slightly less
common, nearly equal mass, and much more tightly bound compared to more massive
binaries. We find that a kick during the ejection of a forming VLM binary from
a close triple or quadruple encounter (imparting a differential kick of ~3 km/s
between the members of the binary) could reproduce the observed cut-off in the
semi-major axis distribution at ~20 AU. However, the estimated binarity (~<5%;
Bate et al. 2002) produced by such "ejection scenarios" is below the 9-15%
observed. Similarly, the dynamical decay models of Sterzik & Durisen (1998);
Durisen, Sterzik, & Pickett (2001) also cannot produce a VLM binary fraction
above ~5%. Our estimate of a fragmentation-produced VLM binary semi-major axis
distribution contains a significant fraction of ``wide'' VLM binaries with a>20
AU in contrast to observation. Hence more detailed theoretical work will be
needed to explain this very interesting VLM binary population.


title:
The Discovery of Two Lyman$\alpha$ Emitters Beyond Redshift 6 in the
  Subaru Deep Field

abstract:
  We have performed a deep optical imaging survey using a narrowband filter
($NB921$) centered at $\lambda =$ 9196 \AA ~ together with $i^\prime$ and
$z^\prime$ broadband filters covering an 814 arcmin$^2$ area of the Subaru Deep
Field. We obtained a sample of 73 strong $NB921$-excess objects based on the
following two color criteria; $z^\prime - NB921 > 1$ and $i^\prime - z^\prime >
1.3$. We then obtained optical spectroscopy of nine objects in our
$NB921$-excess sample, and identified at least two Ly$\alpha$ emitters
at$z=6.541 \pm 0.002$ and $z=6.578 \pm 0.002$, each of which shows the
characteristic sharp cutoff together with the continuum depression at
wavelengths shortward of the line peak. The latter object is more distant than
HCM-6A at $z=6.56$ and thus this is the most distant known object found so far.
These new data allow us to estimate the first meaningful lower limit of the
star formation rate density beyond redshift 6; $\rho_{\rm SFR} \sim 5.2 \times
10^{-4} M_\odot$ yr$^{-1}$ Mpc$^{-3}$. Since it is expected that the actual
density is higher by a factor of several than this value, our new observation
reveals that a moderately high level of star formation activity already
occurred at $z \sim$ 6.6.


title:
The MAHOROBA Project -- Deep Survey with an Optical Intermediate-Band
  Filter System on the Subaru Telescope

abstract:
  We present a summary of the new optical intermediate-band filter system for
the prime-focus camera, Suprime-Cam, on the Subaru telescope at Mauna Kea
Observatories. We also discuss a future plan to promote a new deep survey with
this filter system (the MAHOROBA project).


title: Quasars are more luminous than radio galaxies - so what?

abstract:
  Surveys to find high-redshift radio galaxies deliberately exclude
optically-bright objects, which may be distant radio-loud quasars. In order to
properly determine the space density of supermassive black holes, the fraction
of such objects missed must be determined within a quantitative framework for
AGN unification. I briefly describe the receding torus model, which predicts
that quasars should have more luminous ionizing continua than radio galaxies of
similar radio luminosity, and present evidence to support it. I also suggest
two further tests of the model which should constrain some of its parameters.


title: Separability of Rotational Effects on a Gravitational Lens

abstract:
  We derive the deflection angle up to $O(m^2a)$ due to a Kerr gravitational
lens with mass $m$ and specific angular momentum $a$. It is known that at the
linear order in $m$ and $a$ the Kerr lens is observationally equivalent to the
Schwarzschild one because of the invariance under the global translation of the
center of the lens mass. We show, however, nonlinear couplings break the
degeneracy so that the rotational effect becomes in principle separable for
multiple images of a single source. Furthermore, it is distinguishable also for
each image of an extended source and/or a point source in orbital motion. In
practice, the correction at $O(m^2a)$ becomes $O(10^{-10})$ for the
supermassive black hole in our galactic center. Hence, these nonlinear
gravitational lensing effects are too small to detect by near-future
observations.


title: Current Uncertainties in the Use of Cepheids as Distance Indicators

abstract:
  The methods of calibrating the luminosities of galactic Cepheids and
determining Cepheid reddenings are considered in some detail. Together with
work on NGC4258 this suggests that the calibration presented is valid to about
0.1mag (s.e.) at least for Cepheids with near-solar abundances. Metallicity
effects are considered, partly through the use of non-Cepheid moduli of the
LMC. To reduce the uncertainty substantially below 0.1mag will require
extensive work on metallicity effects. Non-linearities in the period-luminosity
and period-colour relations will also need to be considered as will the need to
distinguish unambiguously between fundamental and overtone pulsators.


title: Miras and Other Cool Variables with GAIA

abstract:
  A general review is given of Mira and other cool variable stars,
concentrating on those aspects on which GAIA, and more particularly GAIA
spectroscopy and radial velocities, will have a major impact.


title: Iterative techniques for the decomposition of long-slit spectra

abstract:
  Two iterative techniques are described for decomposing a long-slit spectrum
into the individual spectra of the point sources along the slit and the
spectrum of the underlying background. One technique imposes the strong
constraint that the spectrum of the background is spatially-invariant; the
other relaxes this constraint. Both techniques are applicable even when there
are numerous overlapping point sources superposed on a structurally-complex
background. The techniques are tested on simulated as well as real long-slit
data from the ground and from space.


title:
The rotational velocity of the sdOB primary of the eclipsing binary
  system LB 3459 (AA Dor)

abstract:
  We present an analysis of the rotational velocity of the primary of LB 3459
based on 107 new high-resolution and high-S/N ESO VLT UVES spectra. 105 of them
cover a complete orbital period (0.26 d) of this binary system. We have
determined an orbital period of P = 22600.702 +/- 0.005 sec, a radial velocity
amplitude of A_1 = 39.19 +/- 0.05 km/sec, and T_0 = 2451917.152690 +/-
0.000005. From simulations of the He II 4686A line profile (based on NLTE model
atmosphere calculations), we derive v_rot = 47 +/- 5 km/sec.
  We present an animation which shows the orbital movement of the binary
system, its synthetic lightcurve, and compares the phase-dependent variation of
the predicted with the observed He II 4686A line profile.
  The radius of the cool component is almost the same size like Jupiter but its
mass is about 70 times higher than Jupiter's mass. Thus, from its present mass
(M_2 = 0.066 M_sun), the secondary of LB 3459 lies formally within the
brown-dwarf mass range (0.013 - 0.08 M_sun). It might be a former planet which
has survived the previous common-envelope phase and even has gained mass.


title: Towards Cosmological Concordance on Galactic Scales

abstract:
  We use the observed abundance and clustering of galaxies from the 2dFGRS to
determine the matter density Omega_m and the linear amplitude of mass
fluctuations sigma_8. We use a method based on the conditional luminosity
function, which allows straightforward computation of the luminosity dependent
bias of galaxies. In addition, it allows the inclusion of constraints on the
redshift space distortion parameter beta=Omega_m^{0.6}/b, and yields average
mass-to-light ratios as function of halo mass. Using only the luminosity
function and the correlation lengths as function of luminosity we obtain
constraints on Omega_m and sigma_8 that are in good agreement with COBE. Using
additional constraints on the mass-to-light ratios of clusters and on the value
of beta as determined from the 2dFGRS yields Omega_m = (0.27 +/- 0.06) and
sigma_8 = (0.77 +/- 0.06). Adding further constraints from current CMB data, we
obtain Omega_m = (0.25 +/- 0.04) and sigma_8 = (0.78 +/- 0.06). Thus, we find
strong indications that both Omega_m and sigma_8 are significantly lower than
their ``standard'' concordance values of 0.3 and 0.9, respectively. Finally, we
show that the cosmologies favored here predict dark matter haloes that are
significantly less centrally concentrated than for the standard LCDM
concordance model. This may solve both the problem with the rotation curves of
dwarf and LSB galaxies, as well as the problem of simultaneously matching the
galaxy luminosity function and the Tully-Fisher zero-point. (Abridged)


title: Candidate Tidal Dwarf Galaxies in the Compact Group CG J1720-67.8

abstract:
  This is the second part of a detailed study of the ultracompact group CG
J1720-67.8: in the first part we have focused the attention on the three main
galaxies of the group and we have identified a number of candidate tidal dwarf
galaxies (TDGs). Here we concentrate on these candidate TDGs. Absolute
photometry of these objects in BVRJHKs bands confirms their relatively blue
colors, as we already expected from the inspection of optical and near-infrared
color maps and from the presence of emission-lines in the optical spectra. The
physical conditions in such candidate TDGs are investigated through the
application of photoionization models, while the optical colors are compared
with grids of spectrophotometric evolutionary synthesis models from the
literature. Although from our data self-gravitation cannot be proved for these
objects, their general properties are consistent with those of other TDG
candidates. Additionally we present the photometry of a few ``knots'' detected
in the immediate surroundings of CG J1720-67.8 and consider the possibility
that these objects might belong to a dwarf population associated with the
compact group.


title: The source content of low galactic latitude XMM-Newton surveys

abstract:
  We present results from a project conducted by the Survey Science Center of
the XMM-Newton satellite and aiming at the identification and characterisation
of serendipitous EPIC sources at low galactic latitudes. Deep multi-colour
optical imaging and spectroscopic observations have been obtained in the
framework of several observing campaigns carried out at ING, CFHT and ESO.
These observations have lead to a number of optical identifications, mostly
with active stars. We describe the identified source content at low galactic
latitudes and compare stellar populations properties at low and high galactic
latitudes with those expected from stellar X-ray count models.


title: Classification of Supernovae

abstract:
  The current classification scheme for supernovae is presented. The main
observational features of the supernova types are described and the physical
implications briefly addressed. Differences between the homogeneous
thermonuclear type Ia and similarities among the heterogeneous core collapse
type Ib, Ic and II are highlighted. Transforming type IIb, narrow line type
IIn, supernovae associated with GRBs and few peculiar objects are also
discussed.


title: CG J1720-67.8: Radio and Integral Field Optical Observations

abstract:
  Our previous studies of the ultracompact galaxy group CG J1720-67.8 have
revealed properties, which suggest that the group is in a very advanced
evolutionary state. We present here new observations in the radio and optical
regimes, which have been obtained in order to further investigate the dynamical
and evolutionary state of the group. Velocity fields reconstructed from
integral field spectra of two regions of the group, obtained with SPIRAL at the
Anglo-Australian Telescope (AAT), show some degree of distortion and a
considerable velocity gradient across one of the TDG candidates. Estimates of
the HI content and of the overall star formation rate of the group are obtained
from radio observations with the Australia Telescope Compact Array (ATCA) in
the 21 cm line and in the 20 cm continuum.


title: The starburst-AGN of NGC1808 observed with XMM-Newton

abstract:
  NGC1808 is a nearby spiral galaxy that harbours an active central region with
an extent of 20 arcsec (i.e. 1 kpc). Previous X-ray and optical/NIR
observations have provided convincing evidence for the existence of a starburst
and an AGN. We present here preliminary results of the analysis of XMM-Newton
data. We show a weak high-resolution soft X-ray spectrum with only emission
lines typical of a starburst. Our analysis of the EPIC-pn spectrum shows two
thermal components, but there is an additional, hard X-ray power law tail that
is most likely due to an obscured active nucleus. Thus, our data show for the
first time the presence of emission from both components, AGN and starburst, in
one observation.


title: 2-D spectroscopy and modeling of the biconical ionized gas in NGC 4388

abstract:
  We present recent results from spectroscopic data and modeling of the
biconical ionized gas in the Seyfert-2 galaxy NGC 4388. A field of ~2.6 x 2.4
kpc centered on the nucleus has been observed by means of the modern technique
of integral field spectroscopy. The analysis of more than two hundred spectra
allowed to study the physical characteristics of the gas in the surroundings of
the active nucleus. The South-West ionization cone, revealed by the [O
III]5007/H-beta excitation map, shows high emission line ratios not completely
supported by simple photoionization. Composite models which account for the
combined effects of photoionization and shock show that such high [O
III]/H-beta line ratios are emitted by low density (n_0=30 cm^-3) gas inside
large (D > 1 pc) shocked clouds (V_s=100 km/s) reached by a relatively low flux
from the active nucleus. The data of the VEELR in the North-East cone by
Yoshida et al. (2002) have been modeled. The results confirm that
photoionization is the prevailing mechanism, but nontheless weak shocks are
under way between colliding clouds with small (< 1 pc) sizes and low densities
n_0 <= 100 cm^-3, moving outward at relatively low velocities (V_s=100 km/s).


title:
Assessing the Effects of the Uncertainty in Reheating Energy Scale on
  Primordial Spectrum and CMB

abstract:
  The details of reheating energy scale $\rho_{reh}$ is largely uncertain
today, independent of inflation models. This would induce uncertainty in
predicting primordial spectrum. Such uncertainty could be very large,
especially for spectra with large running $n_S$. We find that for some
inflation models with a large $d\ln n_S(k)/d\ln k$, $\rho_{reh}$ could be
highly restricted by current CMB observations.


title: Damping of Neutron Star Shear Modes by Superfluid Friction

abstract:
  The forced motion of superfluid vortices in shear oscillations of rotating
solid neutron star matter produces damping of the mode. A simple model of the
unpinning and repinning processes is described, with numerical calculations of
the consequent energy decay times. These are of the order of 1 s or more for
typical anomalous X-ray pulsars but become very short for the general
population of radio pulsars. The superfluid friction processes considered here
may also be significant for the damping of r-modes in rapidly rotating neutron
stars.


title: Evolution of bimodal accretion flows

abstract:
  We consider time-dependent models for rotating accretion flows onto black
holes, where a transition takes place from an outer cooling-dominated disc to a
radiatively inefficient flow in the inner region. In order to allow for a
transition of this type we solve the energy equation, both, for the gas and for
the radiation field, including a radiative cooling flux and a turbulent
convective heat flux directed along the negative entropy gradient. The
transition region is found to be highly variable, and a corresponding variation
expected for the associated total luminosity. In particular, rapid oscillations
of the transition radius are present on a timescale comparable with the local
Keplerian rotation time. These oscillations are accompanied by a quasi-periodic
modulation of the mass flux at the outer edge of the advection-dominated
accretion flow (ADAF). We speculate about the relevance for the high-frequency
QPO phenomenon.


title: VLT observations of the solitary millisecond pulsar PSR J2124-3358

abstract:
  About 100 millisecond (ms) pulsars have been identified in the Galaxy, and
only ~10% of them are solitary, i.e. without a binary companion. Nothing is
known on the optical emission properties of millisecond pulsars. Observations
of solitary millisecond pulsars are the only way to detect their faint optical
radiation, otherwise buried by the brighter white dwarf companion. As in the
case of solitary, non millisecond pulsars, an X-ray detection represents the
first step for a follow-up identification campaign in the optical. Among the
X-ray detected millisecond pulsars, PSR J2124-3358 stands out as an ideal case
because it is very close (<270 pc) and little absorbed. Here, we report on
recent VLT observations of the PSR J2124-3358 aimed at the identification of
its optical counterpart. No optical emission from the pulsar has been detected
down to a limiting flux of V ~ 27.8.


title: UBVRI Night sky brightness during sunspot maximum at ESO-Paranal

abstract:
  In this paper we present and discuss for the first time a large data set of
UBVRI night sky brightness measurements collected at ESO-Paranal from April
2000 to September 2001. A total of about 3900 images obtained on 174 different
nights with FORS1 were analysed using an automatic algorithm specifically
designed for this purpose. This led to the construction of an unprecedented
database that allowed us to study in detail a number of effects such as
differential zodiacal light contamination, airmass dependency, daily solar
activity and moonlight contribution. Particular care was devoted to the
investigation of short time scale variations and micro-auroral events. The
typical dark time night sky brightness values found for Paranal are similar to
those reported for other astronomical dark sites at a similar solar cycle
phase. The zenith-corrected values averaged over the whole period are 22.3,
22.6, 21.6 20.9 and 19.7 mag arcsec-2 in U, B, V, R and I respectively. In
particular, there is no evidence of light pollution either in the broadband
photometry or in the high-airmass spectra we have analysed. Finally, possible
applications for the exposure time calculators are discussed.


title:
Molecular Gas in Candidate Double-Barred Galaxies II. Cooler, Less Dense
  Gas Associated with Stronger Central Concentrations

abstract:
  We have performed a multi-transition CO study of the centers of seven
double-barred galaxies that exhibit a variety of molecular gas morphologies to
determine if the molecular gas properties are correlated with the nuclear
morphology and star forming activity. Near infrared galaxy surveys have
revealed the existence of nuclear stellar bars in a large number of barred or
lenticular galaxies. High resolution CO maps of these galaxies exhibit a wide
range of morphologies. Recent simulations of double-barred galaxies suggest
that variations in the gas properties may allow it to respond differently to
similar gravitational potentials. We find that the 12CO J=3-2/J=2-1 line ratio
is lower in galaxies with centrally concentrated gas distributions and higher
in galaxies with CO emission dispersed around the galactic center in rings and
peaks. The 13CO/12CO J=2-1 line ratios are similar for all galaxies, which
indicates that the J=3-2/J=2-1 line ratio is tracing variations in gas
temperature and density, rather than variations in optical depth. There is
evidence that the galaxies which contain more centralized CO distributions are
comprised of molecular gas that is cooler and less dense. Observations suggest
that the star formation rates are higher in the galaxies containing the warmer,
denser, less centrally concentrated gas. It is possible that either the bar
dynamics are responsible for the variety of gas distributions and densities
(and hence the star formation rates) or that the star formation alone is
responsible for modifying the gas properties.


title:
The BL Lac objects OQ 530 and S5 0716+714. Simultaneous observations in
  the X-rays, radio, optical and TeV bands

abstract:
  We present the results of the BeppoSAX observations of two BL Lacs, OQ 530
and S5 0716+714, as part of a ToO program for the simultaneous observation at
radio, optical, X-ray and TeV energies. Both sources are detected in the LECS
and MECS, with S5 0716+714 visible also in the PDS band, up to about 60 keV.
The X-ray spectra of both sources are better fitted by a double power-law
model, with a steep soft X-ray component flattening at harder energies, with
breaks at 0.3 and 1.5 keV, respectively. The concave shape of the spectra in
both objects is consistent with soft X-rays being produced by the synchrotron
and harder X-rays by the inverse Compton processes. Also the X-ray variability
properties confirm this scenario, in particular for S5 0716+714 our observation
shows variations by about a factor 3 over one hour below 3 keV and no
variability above. Their simultaneous broad band energy spectral distributions
can be successfully interpreted within the frame of a homogeneous synchrotron
and inverse Compton model, including a possible contribution from an external
source of seed photons with the different spectral states of S5 0716+714 being
reproduced by changing the injected power. The resulting parameters are fully
consistent with the two sources being intermediate objects within the
"sequence" scenario proposed for blazars.


title: Accretion in Compact Binaries

abstract:
  Compact binaries have long been a paradigm for accretion theory. Much of our
present view of how accretion occurs comes directly from the comparison of
theory with observations of these sources. Since theory differs little for
other objects such as active galaxies, increasing efforts have recently gone
into searching for correspondences in observed behaviour. This chapter aims at
giving a concise summary of the field, with particular emphasis on new
developments since the previous edition of this book. These developments have
been significant. Much of the earlier literature implicitly assumed that
accreting binaries were fairly steady sources accreting most of the mass
entering their vicinity, often with main-sequence companions, and radiating the
resulting accretion luminosity in rough isotropy. We shall see that in reality
these assumptions fail for the majority of systems. Most are transient; mass
ejection in winds and jets is extremely common; a large (sometimes dominant)
fraction of even short-period systems have evolved companions whose structure
deviates significantly from the zero-age main sequence; and the radiation
pattern of many objects is significantly anisotropic. It is now possible to
give a complete characterization of the observed incidence of transient and
persistent sources in terms of the disc instability model and formation
constraints. X-ray populations in external galaxies, particularly the
ultraluminous sources, are revealing important new insights into accretion
processes and compact binary evolution.


title: Physical conditions in the planetary nebula Abell 30

abstract:
  We have analysed optical spectra of two of the hydrogen-deficient knots (J1 &
J3) in the born-again planetary nebula Abell 30, together with UV spectra of
knots J3 & J4. We determine electron temperatures in the knots based on several
diagnostics. The [O III] nebular-to-auroral transition ratio yields
temperatures of the order of 17 000 K. The weak temperature dependence of the
ratios of helium lines at 4471, 5876 and 6678 Angstroms is used to derive a
temperature of 8850 K for knot J3 and 4600 K for knot J1. Ratios of O II
recombination lines, which directly measure the temperature in the coldest
regions of the knots, are used to derive temperatures of 2500 K for knot J3,
and just 500 K for knot J1.
  We calculate abundances both from collisionally excited lines and from the
well-observed recombination spectra of C, N, O and Ne ions. The forbidden line
abundances agree well with previous determinations, but the recombination line
abundances are several hundred times higher. These results confirm the scenario
proposed by Harrington and Feibelman (1984) in which the knots contain a cold
core highly enriched in heavy elements. Forbidden lines are almost entirely
emitted by the hot outer part of the knot, while recombination lines are
emitted predominantly from the cold core. The C/O ratios we derive imply that
the knots are oxygen-rich, contrary to theoretical predictions for born-again
nebulae (Iben et al 1983).


title: Gamma-Ray Lines from Asymmetric Supernovae

abstract:
  We present 3-dimensional SPH simulations of supernova explosions from 100
seconds to 1 year after core-bounce. By extending our modelling efforts to a
3-dimensional hydrodynamics treatment, we are able to investigate the effects
of explosion asymmetries on mixing and gamma-ray line emergence in supernovae.
A series of initial explosion conditions are implemented, including jet-like
and equatorial asymmetries of varying degree. For comparison, symmetric
explosion models are also calculated. A series of time slices from the
explosion evolution are further analyzed using a 3-dimensional Monte Carlo
gamma-ray transport code. The emergent hard X- and gamma-ray spectra are
calculated as a function of both viewing angle and time, including trends in
the gamma-ray line profiles. We find significant differences in the velocity
distribution of radioactive nickel between the symmetric and asymmetric
explosion models. The effects of this spatial distribution change are reflected
in the overall high energy spectrum, as well as in the individual gamma-ray
line profiles.


title: The Dust in Lyman Break Galaxies

abstract:
  We present our analysis of UV attenuation by internal dust of a large sample
(N=906 galaxies) of Lyman Break Galaxies (LBGs). Using spectral energy
distributions (SEDs) from the P\'EGASE galaxy spectral evolution model we apply
dust attenuation corrections to the G-R colors using the Witt & Gordon (2000)
models for radiative transfer in dusty galactic environments to arrive at the
UV attenuation factors. We show that the dust in the LBGs exhibit SMC-like
characteristics rather than MW-like, and that the dust geometry in these
systems is most likely to be represented by a clumpy shell configuration. We
show that the attenuation factor exhibits a pronounced dependence on the
luminosity of the LBG, $a_{1600}\propto (L/L_\sun)^\alpha$, where
$0.5\leq\alpha\leq1.5$. The exponent $\alpha$ depends on the initial parameters
of the stellar population chosen to model the galaxies and the dust properties.
We find that the luminosity weighted average attenuation factor is likely to be
in the range from $5.7-18.5$, which is consistent with the upper limits to the
star formation rate at $2<z<4$ set by the FIR background. This implies that the
current UV/optical surveys do detect the bulk of the star formation during the
epoch $2<z<4$, but require substantial correction for internal dust
attenuation.


title: A Point Source Excess in Abell 1185: Intergalactic Globular Clusters?

abstract:
  Deep imaging with WFPC2 and the Hubble Space Telescope has been used to
search for a population of intergalactic globular clusters (GCs) belonging to
Abell 1185, a richness I cluster at cz = 9800 km/s. The field is noteworthy in
that it contains no bright galaxies and yet is centered on the peak of the
cluster's X-ray surface brightess distribution. We detect a total of 99 point
sources in this field to a limiting magnitude I_F814W ~ 26. An identical
analysis of the Hubble Deep Field North, which serves as our control field,
reveals a total of 12 objects in the same magnitude range. We discuss possible
explanations for this discrepancy, and conclude that the point source excess is
likely due to the presence of GCs within A1185. The number and spatial
distribution of these GCs are consistent with their being intergalactic in
nature, although we cannot rule out the possibility that some of the GCs may be
associated with neighboring bright galaxies. Deeper imaging with the Advanced
Camera for Surveys may resolve this ambiguity.


title:
The temperature and distribution of gas in CL 0016+16 measured with
  XMM-Newton

abstract:
  We present results of a 37 ks observation of CL 0016+16 with the XMM-Newton
EPIC instrument. Within 1.5 arcmin of the cluster centre we measure a gas
temperature of kT = 9.13^{+0.24}_{-0.22} keV and an abundance of
0.22^{+0.04}_{-0.03} times the solar value (1 sigma uncertainties). This
significant improvement over previous measurements has allowed us to revise the
estimate of the Hubble constant based on CL 0016+16 to 68 +/- 8 km s^{-1}
Mpc^{-1} (random error only), close to the value from the Hubble Space
Telescope distance-scale project. The total gravitating mass within a radius of
248 kpc of the cluster centre is in good agreement with that found from
gravitational lensing over the same region, supporting the assumption of
isothermal gas in hydrostatic equilibrium. The gas mass fraction of 0.13 +/-
0.02 is in remarkable agreement with that given by cosmological parameters for
the Universe as a whole, suggesting that CL 0016+16 is a fair sample of the
matter content of the Universe. While there is no spectral or spatial evidence
to suggest a cooling flow in CL 0016+16, we find an asymmetrical central X-ray
structure which may have a harder spectrum than the cluster as a whole, and be
evidence for some merger activity, in addition to a previously reported
asymmetry to the west of the cluster. The nearest companion cluster to CL
0016+16 is measured to have a gas temperature of kT = 3.8^{+0.3}_{-0.3} keV and
an abundance of 0.6^{+0.3}_{-0.2} times the solar value (1 sigma
uncertainties). We also present spectral data for the companion quasar whose
spectrum was confused with CL 0016+16 in previous ASCA data.


title:
Detections of Ro-Vibrational H$_2$ Emission from the Disks of T Tauri
  Stars

abstract:
  We report the detection of quiescent H_2 emission in the v=1-0 S(1) line at
2.12183 um in the circumstellar environment of two classical T Tauri stars, GG
Tau A and LkCa 15, in high-resolution (R 60,000) spectra, bringing to four,
including TW Hya and the weak-lined T Tauri star DoAr 21, the number of T Tauri
stars showing such emission. The equivalent widths of the H_2 emission line lie
in the range 0.05-0.10 \AA and, in each case, the central velocity of the
emission line is centered at the star's systemic velocity. The line widths
range from 9 to 14 km s^{-1}, in agreement with those expected from gas in
Keplerian orbits in circumstellar disks surrounding K-type stars at distances >
10 AU from the sources. We suggest that UV fluorescence and X-ray heating are
likely candidates responsible for producing the observed emission. We present
mass estimates from the measured line intensities and show that the estimated
masses are consistent with those expected from the possible mechanisms
responsible for stimulating the observed emission. The high temperatures and
low densities required for significant emission in the v=1-0 S(1) line suggests
that we have detected reservoirs of hot H_2 gas located in the low density,
upper atmospheres of circumstellar disks of these stars.


title: X-ray Emission Processes in Extragalactic Jets, Lobes and Hot Spots

abstract:
  This paper is a brief review of the processes responsible for X-ray emission
from radio jets, lobes and hot spots. Possible photons in inverse Compton
scattering models include the radio synchrotron radiation itself (i.e.
synchrotron self-Compton [SSC] emission), the cosmic microwave background
(CMB), the galaxy starlight and radiation from the active nucleus. SSC emission
has been detected from a number of hot spots. Scattering of the CMB is expected
to dominate for jets (and possibly hot spots) undergoing bulk relativistic
motion close to the direction towards the observer. Scattering of infrared
radiation from the AGN should be observable from radio lobes, especially if
they are close to the active nucleus. Synchrotron radiation is detected in some
sources, most notably the jet of M87. I briefly discuss why different hot spots
emit X-rays by different emission mechanisms and the nature of the synchrotron
spectra.


title: A Multi-Transistion CO Study of the "Antennae" Galaxies NGC4038/9

abstract:
  For the Antennae interacting galaxy pair, we have obtained high quality,
fully sampled $^{12}$CO J=1-0, 2-1 and 3-2 maps of the regions surrounding the
nuclei and the area of overlap between the two galaxies, with an angular
resolution of 15" or 1.5 kpc. The $^{12}$CO J=1-0, 2-1, 3-2 emission all peak
in the overlap region, which contains ~ 4 x 10^9 solar mass of molecular gas
mass if the conventional X factor is used. Line emission at $^{13}$CO J=2-1 and
3-2 is detected at selected points in the two nuclei and the overlap region.
Both the ^{12}CO/^{13}CO J=2-1 and 3-2 integrated intensity ratios are
remarkably high in the overlap region. This is the first published case in
which such high $^{12}$CO/$^{13}$CO J=2-1 and 3-2 ratios are found outside a
galactic nucleus. Detailed LVG modeling indicates that the $^{12}$CO and
^{13}CO emission originate in different spatial components. Assuming a CO-to-H2
abundance ratio of $10^{-4}$, the X factor given by the LVG model is an order
of magnitude lower than the conventional value for molecular clouds in the
Milky Way. Accordingly, we suggest the possibility that the strong CO emission
in the overlap region of the Antennae galaxies is associated with increased
radiative efficiency, possibly caused by a large velocity dispersion within the
individual molecular clouds. A comparison of the CO J=3-2 emission with the
SCUBA 850 um continuum in the Antennae galaxies shows that the CO line emission
contributes globally 46% of the 850 um continuum flux and that the ratio of
$^{12}$CO J=3-2 to SCUBA 850 um flux varies by a factor of two across the
system.


title: Dynamical Evidence for a Black Hole in GX 339-4

abstract:
  We present outburst spectroscopy of GX339-4 which may reveal the motion of
its elusive companion star. NIII lines exhibit sharp emission components moving
over ~300 km/s in a single night. The most plausible interpretation of these
components is that they are formed by irradiation of the companion star and the
velocities indicate its orbital motion. We also detect motion of the wings of
the HeII 4686A line and changes in its morphology. No previously proposed
period is consistent with periodic behavior of all of these measures. However,
consistent and sensible solutions are obtained for periods around 1.7 days. For
the best period, 1.7557 days, we estimate a mass function of 5.8 +/- 0.5 Msun.
Even allowing for aliases, the 95% confidence lower-limit on the mass function
is 2.0 Msun. GX339-4 can therefore be added to the list of dynamical black hole
candidates. This is supported by the small motion in the wings of the HeII
line; if the compact object velocity is not larger than the observed motion
then the mass ratio is q < 0.08, similar to other systems harboring black
holes. Finally, we note that the sharp components are not always present, but
do seem to occur within a repeating phase range. This appears to migrate
between our epochs of observation, and may indicate shielding of the companion
star by a variable accretion geometry such as a warp.


title: Near-Earth Observations by Spread Telescopes

abstract:
  We suggest the all-sky survey at the International Space Station by four
little wide-angle telescopes with polarization filters and CCD-arrays spread by
several meters one from another. The video information processing will be
carried out by real-time multiprocessor system on the board of the station.
This experiment would allow to observe the sunlit space debris and meteoroids
of centimetre size with their distances and velocities estimations at the
distances up to 20 km from station and to investigate the interplanetary and
interstellar medium by the making of polarization sky maps and detecting the
weak-contrast features on it.


title: Spectroscopy of planetary nebulae in M33

abstract:
  Spectroscopic observations of 48 emission-line objects of M33 have been
obtained with the multi-object, wide field, fibre spectrograph AF2/WYFFOS at
the 4.2m WHT telescope (La Palma, Spain). Line intensities and logarithmic
extinction, cbeta, are presented for 42 objects. Their location in the Sabbadin
& D'Odorico diagnostic diagram (Halpha/[SII] vs Hlapha/[NII]) suggests that
>70% of the candidates are Planetary Nebulae (PNe). Chemical abundances and
nebular physical parameters have been derived for the three of the six PNe
where the 4363A [OIII] emission line was measurable. These are disc PNe,
located within a galactocentric distance of 4.1 kpc, and, to date, they are the
farthest PNe with a direct chemical abundance determination. No discrepancy in
the Helium, Oxygen and Argon abundances has been found in comparison with
corresponding abundances of PNe in our Galaxy. Only a lower limit to the
sulphur abundance has been obtained since we could not detect any [SIII] line.
N/H appears to be lower than the Galactic value; some possible explanations for
this under-abundance are discussed.


title:
Simultaneous BeppoSAX and Rossi X-ray Timing Explorer observations of
  4U1812-12

abstract:
  4U1812-12 is a faint persistent and weakly variable neutron star X-ray
binary. It was observed by BeppoSAX between April 20th and 21st, 2000 in a hard
spectral state with a bolometric luminosity of ~2x10^36 ergs/s. Its broad band
energy spectrum is characterized by the presence of a hard X-ray tail extending
above ~100 keV. It can be represented as the sum of a dominant hard Comptonized
component (electron temperature of ~36 keV and optical depth ~3) and a weak
soft component. The latter component which can be fitted with a blackbody of
about 0.6 keV and equivalent radius of ~2 km is likely to originate from the
neutron star surface. We also report on the first measurement of the power
density spectrum of the source rapid X-ray variability, as recorded during a
simultaneous snapshot observation performed by the Rossi X-ray Timing Explorer.
As expected for a neutron star system in such hard spectral state, its power
density spectrum is characterized by the presence of a ~0.7 Hz low frequency
quasi-periodic oscillation together with three broad noise components, one of
which extends above ~200 Hz.


title: The Future of Microwave Background Physics

abstract:
  The cosmic microwave background is now fulfilling its promise of determining
the basic cosmological parameters describing our Universe. Future study of the
microwave background will mostly be directed towards two basic questions: a
complete characterization of the initial perturbations, and probes of the
nonlinear evolution of structure in the Universe. The basic scientific issues
in both of these areas are reviewed here, along with possibilities for
addressing them with further microwave background measurements at higher
sensitivities and smaller angular scales. The proposed ACT experiment, which
will map 200 square degrees of sky at arcminute resolution and micro-Kelvin
sensitivity in three microwave frequency bands, is briefly described as an
example of rapidly advancing experimental technique.


title:
A Fourier-Based Algorithm for Modelling Aberrations in HETE-2's Imaging
  System

abstract:
  The High-Energy Transient Explorer (HETE-2), launched in October 2000, is a
satellite experiment dedicated to the study of gamma-ray bursts in a very wide
energy range from soft X-ray to gamma-ray wavelengths. The intermediate X-ray
range (2-30keV) is covered by the Wide-field X-ray Monitor WXM, a coded
aperture imager. In this article, an algorithm for reconstructing the positions
of gamma-ray bursts is described, which is capable of correcting systematic
aberrations to approximately 1 arcmin throughout the field of view.
Functionality and performance of this algorithm have been validated using data
from Monte Carlo simulations as well as from astrometric observations of the
X-ray source Scorpius X-1.


title:
What can we learn on the thermal history of the Universe from future CMB
  spectrum measures at long wavelengths?

abstract:
  We analyse the implications of future observations of the CMB absolute
temperature at centimeter and decimeter wavelengths, necessary to complement
the accurate COBE/FIRAS data.
  Our analysis shows that forthcoming ground and balloon measures will allow a
better understanding of free-free distortions but will not be able to
significantly improve the constraints already provided by the FIRAS data on the
possible energy exchanges in the primeval plasma. The same holds even improving
the sensitivity up to ~10 times.
  Thus, we have studied the impact of very high quality data, such those in
principle achievable with a space experiment like DIMES planned to measure the
CMB absolute temperature at 0.5 - 15 cm with a sensitivity of ~0.1 mK, close to
that of FIRAS. Such high quality data would improve by a factor ~50 the FIRAS
results on the fractional energy exchanges associated to dissipation processes
possibly occurred in a wide range of cosmic epochs, at intermediate and high
redshifts (y_h > 1). The energy dissipation epoch could be also significantly
constrained, while the limits on the energy possibly dissipated at late epochs
can be improved by a factor ~2. In addition, such measures can provide an
independent and very accurate cross-check of FIRAS calibration. Finally, a
DIMES-like experiment will be able to provide indicative independent estimates
of the baryon density.


title:
UV to radio centimetric spectral energy distributions of
  optically-selected late-type galaxies in the Virgo cluster

abstract:
  We present a multifrequency dataset for an optically-selected,
volume-limited, complete sample of 118 late-type galaxies (>= S0a) in the Virgo
cluster. The database includes UV, visible, near-IR, mid-IR, far-IR, radio
continuum photometric data as well as spectroscopic data of Halpha, CO and HI
lines, homogeneously reduced, obtained from our own observations or compiled
from the literature. Assuming the energy balance between the absorbed stellar
light and that radiated in the IR by dust, we calibarte an empirical
attenuation law suitable for correcting photometric and spectroscopic data of
normal galaxies. The data, corrected for internal extinction, are used to
construct the spectral energy distribution (SED) of each individual galaxy, and
combined to trace the median SED of galaxies in various classes of
morphological type and luminosity. Low-luminosity, dwarf galaxies have on
average bluer stellar continua and higher far-IR luminosities per unit galaxy
mass than giant, early-type spirals. If compared to nearby starburst galaxies
such as M82 and Arp 220, normal spirals have relatively similar observed
stellar spectra but 10-100 times lower IR luminosities. The temperature of the
cold dust component increases with the far-IR luminosity, from giant spirals to
dwarf irregulars. The SED are used to separate the stellar emission from the
dust emission in the mid-IR regime. We show that the contribution of the
stellar emission at 6.75 micron to the total emission of galaxies is generally
important, from ~ 80% in Sa to ~ 20% in Sc.


title:
A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey II: Discovery
  of Three Additional Quasars at z>6

abstract:
  We present the discovery of three new quasars at z>6 in 1300 deg^2 of SDSS
imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23) and
J163033.90+401209.6 (z=6.05). The first two objects have weak Ly alpha emission
lines; their redshifts are determined from the positions of the Lyman break.
They are only accurate to 0.05 and could be affected by the presence of broad
absorption line systems. The last object has a Ly alpha strength more typical
of lower redshift quasars. Based on a sample of six quasars at z>5.7 that cover
2870 deg^2 presented in this paper and in Paper I, we estimate the comoving
density of luminous quasars at z 6 and M_{1450} < -26.8 to be (8 +/-
3)x10^{-10} Mpc^{-3} (for H_0 = 50 km/s/Mpc, Omega = 1). HST imaging of two
z>5.7 quasars and high-resolution ground-based images (seeing 0.4'') of three
additional z>5.7 quasars show that none of them is gravitationally lensed. The
luminosity distribution of the high-redshfit quasar sample suggests the bright
end slope of the quasar luminosity function at z 6 is shallower than Psi
L^{-3.5} (2-sigma), consistent with the absence of strongly lensed objects.


title: Hydrodynamical simulations of a cloud of interacting gas fragments

abstract:
  We present a full hydrodynamical investigation of a system of self-contained,
interacting gas `cloudlets'. Calculations are performed using SPH, and
cloudlets are allowed to collide, dissipate kinetic energy, merge and undergo
local gravitational collapse. The numerical feasibility of such a technique is
explored, and the resolution requirements examined. We examine the effect of
the collision time and the velocity field on the timescale for evolution of the
system, and show that almost all star formation will be confined to dense
regions much smaller than the entire cloud. We also investigate the
possibility, discussed by various authors, that such a system could lead to a
power-law IMF by a process of repeated cloudlet coagulation, finding that in
fact the inter-cloudlet collisions occur at too high a Mach number for merging
to play an important part.


title: Cosmological Parameters: Fashion and Facts

abstract:
  We are at a specific period of modern cosmology, during which the large
increase of the amount of data leads to the idea that the determination of
cosmological parameters has been achieved with a rather good precision. There
is a large consensus around the so-called concordance model. Indeed this model
does fit an impressive set of independent data: CMB $C_l$ curve, most current
matter density estimations, Hubble constant estimation from HST, apparent
acceleration of the Universe, good matching of the power spectrum of matter
fluctuations. However, the necessary introduction of a non zero cosmological
constant is an extraordinary new mystery for physics, or more exactly the come
back of one of the ghost of modern physics since its introduction by Einstein.
Here, I would like to emphasize that some results are established beyond
reasonable doubt, like the (nearly) flatness of the universe and the existence
of a dark non-baryonic component of the Universe. But also that the evidence
for a cosmological constant may not be as strong as needed to be considered as
established beyond doubt. In this respect, I will argue that an Einstein-De
Sitter universe might still be a viable option. Three global tests: 1) the
evolution of the abundance of clusters with redshift 2) the baryon fraction
measured in local clusters 3) apparent evolution of the baryon fraction with
redshift might be consistent with a high matter density for the Universe in the
range $0.6-1.$. I therefore conclude that the dominance of vacuum to the
various density contributions to the Universe is presently an interesting and
fascinating possibility, but it is still premature to consider it as an
established scientific fact (abridged).


title: Electromagnetic Radiation and Motion of a Particle

abstract:
  We consider the motion of uncharged dust grains of arbitrary shape including
the effects of electromagnetic radiation and thermal emission. The resulting
relativistically covariant equation of motion is expressed in terms of standard
optical parameters. Explicit expressions for secular changes of osculating
orbital elements are derived in detail for the special case of the
Poynting-Robertson effect. Two subcases are considered: (i) central
acceleration due to gravity and the radial component of radiation pressure
independent of the particle velocity, (ii) central acceleration given by
gravity and the radiation force as the disturbing force. The latter case yields
results which may be compared with secular orbital evolution in terms of
orbital elements for an arbitrarily shaped dust particle. The effects of solar
wind are also presented.


title: On Tripolar Magnetic Reconnection and Coronal Heating

abstract:
  Using recent data for the photosphere-chromosphere region of the solar
atmosphere the magnetic reconnection in tripolar geometry has been investigated
through the procedure of Sturrock (1999). Particular attention has been given
to the width of the reconnecting region, wave number of the rapidly growing
tearing mode, island length scales, frequency of MHD fluctuations, tearing mode
growth rate, energy dissipation rate and minimum magnetic field strength
required to heat chromospheric plasma to coronal temperatures. It is found that
small length scales are formed in the upper chromosphere. The maximum growth
rate of tearing mode instability coincides with the peak in the energy
dissipation rate both of which occur in the upper chromosphere at the same
height. It is realized that the distribution of magnetic field with height is
essential for a better understanding of the coronal heating problem.


title:
The calibration of interferometric visibilities obtained with
  single-mode optical interferometers. Computation of error bars and
  correlations

abstract:
  I present in this paper a method to calibrate data obtained from optical and
infrared interferometers. I show that correlated noises and errors need to be
taken into account for a very good estimate of individual error bars but also
when model fitting the data to derive meaningful model parameters whose
accuracies are not overestimated. It is also shown that under conditions of
high correlated noise, faint structures of the source can be detected. This
point is important to define strategies of calibration for difficult programs
such as exoplanet detection. The limits of validity of the assumptions on the
noise statistics are discussed.


title: XMM-Newton study of hard X-ray sources in IC443

abstract:
  We present \xmm observations of hard X-ray emission from the field of IC443,
a supernova remnant interacting with a molecular cloud. The hard emission from
the field is dominated by 12 isolated sources having 2--10 keV flux $\ga
10^{-14}$ $\enf$. Only a fraction of the sources are expected to be
extragalactic or stars on statistical grounds, while the others may be
associated with the remnant. We have analyzed near-infrared K band and also DSS
optical data for all of the detected sources, finding that six X-ray sources
are located in a relatively small $15^\prime\times 15^\prime$ region where
there is strong 2.2 $\mu {\rm m}$ infrared emission, indicating interaction
with a molecular cloud. The source 1SAX J0618.0+2227, the brightest in this
region (excluding the plerion), is resolved with \xmm into two sources, one of
which is extended and has a hard power law spectrum photon index $\lsim$ 1.5)
and shows some indications of spectral line signatures (e.g. Si), while the
other is point-like and has a featureless spectrum of steeper photon index
$\sim$ 2.2. Possible interpretations of some of the discrete sources in terms
of interaction between the SNR and the molecular cloud are discussed.


title: Spectra from a magnetic reconnection-heated corona in AGN

abstract:
  We investigate a corona coupled with underlying disk through magnetic field
and radiation field, and present emergent spectra calculated from Monte Carlo
simulations. The spectra are determined for given black-hole mass and accretion
rate. We find two types of solutions corresponding for hard spectrum and soft
spectrum. In the hard-spectrum solution, the accretion energy is dominantly
dissipated in the corona, supporting a strong corona above a cool disk; The
hard X-ray spectral indices are around 1.1, same for different accretion rates.
In the soft-spectrum solution, the accretion energy is mainly dissipated in the
disk. The coronal temperature and density are quite low. Consequently, the
spectra are dominated by the disk radiation peaking at UV and soft X-rays. For
low-luminosity systems, there exists only the solution of hard spectra; While
for high-luminosity systems, there exist both solutions of hard and soft
spectra. For middle-luminosity systems, besides the hard spectra, moderately
soft spectra composed of an inner soft-spectrum solution and an outer
hard-spectrum solution may occur, the softness of which increases with
increasing luminosity. The hard spectra are close to the observed spectra in
Seyfert galaxies and radio-quiet QSOs. The composite spectra may account for
the diversity of broad band spectra observed in narrow-line Seyfert 1 galaxies.


title: High-energy Neutrino Astronomy: Science and First Results

abstract:
  We introduce neutrino astronomy starting from the observational fact that
Nature accelerates protons and photons to energies in excess of 10^{20} and
10^{13} eV, respectively. Although the discovery of cosmic rays dates back a
century, we do not know how and where they are accelerated. We review the
observations as well as speculations about the sources. Among these gamma ray
bursts and active galaxies represent well-motivated speculations because these
are also the sources of the highest energy gamma rays, with emission observed
up to 20 TeV, possibly higher.
  We discuss why cosmic accelerators are expected to be cosmic beam dumps
producing neutrino beams associated with the highest energy cosmic rays. Cosmic
ray sources may produce neutrinos from MeV to EeV energy by a variety of
mechanisms. The important conclusion is that, independently of the specific
blueprint of the source, it takes a kilometer-scale neutrino observatory to
detect the neutrino beam associated with the highest energy cosmic rays and
gamma rays. The technology for commissioning such instrument has been
established by the AMANDA detector at the South Pole. We review its performance
and, with several thousand neutrinos collected, its first scientific results.


title: Disk-Bulge-Halo Models for the Andromeda Galaxy

abstract:
  We present a suite of semi-analytic disk-bulge-halo models for the Andromeda
galaxy (M31) which satisfy three fundamental conditions: (1) internal
self-consistency; (2) consistency with observational data; and (3) stability of
the disk against the formation of a central bar. The models are chosen from a
set first constructed by Kuijken and Dubinski. We develop an algorithm to
search the parameter space for this set in order to best match observations of
the M31 rotation curve, inner velocity dispersion profile, and surface
brightness profile. Models are obtained for a large range of bulge and disk
masses; we find that the disk mass must be of order 8 * 10^10 M_sun and that
the preferred value for the bulge mass is 2.5 * 10^10 M_sun. N-body simulations
are carried out to test the stability of our models against the formation of a
bar within the disk. We also calculate the baryon fraction and halo
concentration parameter for a subset of our models and show that the results
are consistent with the predictions from cosmological theories of structure
formation. In addition, we describe how gravitational microlensing surveys and
dynamical studies of globular clusters and satellites can further constrain the
models.


title: Propagation Speed of Gravity and the Relativistic Time Delay

abstract:
  We calculate the delay in the propagation of a light signal past a massive
body that moves with speed v, under the assumption that the speed of
propagation of the gravitational interaction c_g differs from that of light.
Using the post-Newtonian approximation, we consider an expansion in powers of
v/c beyond the leading ``Shapiro'' time delay effect, while working to first
order only in Gm/c^2, and show that the altered propagation speed of the
gravitational signal has no effect whatsoever on the time delay to first order
in v/c beyond the leading term, although it will have an effect to second and
higher order. We show that the only other possible effects of an altered speed
c_g at this order arise from a modification of the parametrized post-Newtonian
(PPN) coefficient \alpha_1 of the metric from the value zero predicted by
general relativity. Current solar-system measurements already provide tight
bounds on such a modification. We conclude that recent measurements of the
propagation of radio signals past Jupiter are sensitive to \alpha_1, but are
not directly sensitive to the speed of propagation of gravity.


title: Geodetic Precession in PSR B1913+16

abstract:
  We review the observational evidence for geodetic precession in PSR B1913+16
and present the latest observations and results from modelling the system
geometry and beam.


title: Galactic Gamma-Ray Halo of the Nearby Starburst Galaxy NGC 253

abstract:
  Recently, the CANGAROO-II telescope detected diffuse TeV gamma-ray emission
from a nearby edge-on starburst galaxy, NGC 253. The emission mechanism is
discussed in this report. We review the emissions of radio-to-TeV gamma-rays
from NGC 253, and present a model of the non-thermal emissions due to
synchrotron radiations and inverse Compton scatterings. A halo model
successfully explains the multiband spectrum of NGC 253.


title:
Constraining the Parameters of AGN Jets - Comparisons with Herbig-Haro
  Jets

abstract:
  Comparing the properties AGN and Herbig-Haro jets can be a useful exercise
for understanding the physical mechanisms at work in collimated outflows that
propagate in such different environments. In the case of Herbig-Haro jets, the
presence of emission lines in the spectra and the continuous evolution of the
observation techniques greatly favor our knowledge of the physical parameters
of the jets instead, for AGN jets, the process of constraining the jet
parameters is hampered by the nature of the emission from these objects that is
non-thermal. I will discuss how one cannot directly constrain the basic
parameters of extragalactic jets by observations but must treat and interpret
the data either by statistical means or by comparing observed and simulated
morphologies in order to gain some indications on the values of these
parameters.


title: Are the hosts of Gamma-Ray Bursts sub-luminous and blue galaxies?

abstract:
  We present K-band imaging observations of ten Gamma-Ray Burst (GRB) host
galaxies. We compare their observed and absolute K magnitudes as well as their
R-K colours with those of other distant sources detected in various optical,
near-infrared, mid-infrared and submillimeter deep surveys. We find that the
GRB host galaxies, most of them lying at 0.5<z<1.5, exhibit very blue colours,
comparable to those of the faint blue star-forming sources at high redshift.
They are sub-luminous in the K-band, suggesting a low stellar mass content. We
do not find any GRB hosts harbouring R- and K-band properties similar to those
characterizing the luminous infrared/submillimeter sources and the extremely
red starbursts. Should GRBs be regarded as an unbiased probe of star-forming
activity, this lack of luminous and/or reddened objects among the GRB host
sample might reveal that the detection of GRB optical afterglows is likely
biased toward unobscured galaxies. It would moreover support the idea that a
large fraction of the optically-dark GRBs occur within dust-enshrouded regions
of star formation. On the other hand, our result might also simply reflect
intrinsic properties of GRB host galaxies experiencing a first episode of very
massive star formation and characterized by a rather weak underlying stellar
population. Finally, we compute the absolute B magnitudes for the whole sample
of GRB host galaxies with known redshifts and detected at optical wavelengths.
We find that the latter appear statistically even less luminous than the
sub-luminous blue sources which mostly contributed to the B-band light emitted
at high redshift. This indicates that the formation of GRBs could be favoured
in particular systems with very low luminosities and, therefore, low
metallicities. (Abridged)


title:
The Enigma of Lithium: from CP Stars to K Giants. First Results of CP
  Star Observations Obtained at Mount Stromlo Observatory

abstract:
  We present the results of the observations of some roAp stars made at Mount
Stromlo Observatory during 17 nights in 2001 September-October. This long
observing run permitted us to obtain a good phase-rotation coverage. In
chemically peculiar magnetic stars, the Li I 6708 A spectral line presents very
anomalous behaviour: in some stars it is a strong feature, in others, with
similar atmospheric parameters, it is invisible. Interesting results were
obtained for the roAp star HD 3980 which presents variations of the profile and
position of the Li I line with the rotation period. These new observational
results should serve as a base for the development of atmospheric models of
``Li-spotted'' roAp stars.


title:
Inner Boundary Conditions for Advection-Dominated Accretion onto Black
  Holes

abstract:
  The structure of the inner region of an advection-dominated accretion disk
around a nonrotating black hole is explored by applying asymptotic analysis in
the region just outside the event horizon. We assume that the viscous transport
is described by the standard Shakura-Sunyaev prescription throughout the disk,
including the inner region close to the horizon. One of our goals is to explore
the self-consistency of this assumption by analyzing the causality of the
viscous transport near the black hole. The effects of general relativity are
incorporated in an approximate manner by utilizing a pseudo-Newtonian
gravitational potential. Analysis of the conservation equations yields unique
asymptotic forms for the behaviors of the radial inflow velocity, the density,
the sound speed, and the angular velocity. The specific behaviors are
determined by three quantities; namely, the accreted specific energy, the
accreted specific angular momentum, and the accreted specific entropy. The
additional requirement of passage through a sonic point further constrains the
problem, leaving only two free parameters. Our detailed results confirm that
the Shakura-Sunyaev viscosity yields a well-behaved flow structure in the inner
region that satisfies the causality constraint. We also show that the velocity
distribution predicted by our pseudo-Newtonian model agrees with general
relativity in the vicinity of the horizon. The asymptotic expressions we derive
provide convenient boundary conditions for the development of global models via
numerical integration of the conservation equations.


title:
An XMM-Newton observation of the Narrow Line Seyfert 1 Galaxy, Markarian
  896

abstract:
  XMM-Newton observations of the NLS1 Markarian 896 are presented. Over the
2-10 keV band, an iron emission line, close to 6.4 keV, is seen. The line is
just resolved and has an equivalent width of ~170 eV. The broad-band spectrum
is well modelled by a power law slope of gamma ~ 2.03, together with two
blackbody components to fit the soft X-ray excess. Using a more physical
two-temperature Comptonisation model, a good fit is obtained for an input
photon distribution of kT ~ 60eV and Comptonising electron temperatures of ~0.3
and 200 keV. The soft excess cannot be explained purely through the
reprocessing of a hard X-ray continuum by an ionised disc reflector.


title: X-ray Scaling Properties of Early-type Galaxies

abstract:
  We present an analysis of 39 X-ray luminous early-type galaxies observed with
the ROSAT PSPC. Using multi-component spectral and spatial fits to these data
we have measured halo abundance, temperature, luminosity and surface brightness
profile. We compare these measurements to similar results from galaxy groups
and clusters, fitting a number of relations commonly used in the study of these
larger objects. In particular, we find that the sigma:Tx relation for our
sample is similar to that reported for clusters, consistent with beta_{spec}=1,
and that the Lx:Tx relation has a steep slope (gradient 4.8+-0.7) comparable
with that found for galaxy groups. Assuming isothermality, we construct
3-dimensional models of our galaxies, allowing us to measure gas entropy. We
find no correlation between gas entropy and system mass, but do find a trend
for low temperature systems to have reduced gas fractions. We conclude that the
galaxies in our sample are likely to have developed their halos through galaxy
winds, influenced by their surrounding environment.


title:
Three-dimensional Calculations of High and Low-mass Planets Embedded in
  Protoplanetary Discs

abstract:
  We analyse the non-linear, three-dimensional response of a gaseous, viscous
protoplanetary disc to the presence of a planet of mass ranging from one Earth
mass (1 M$_e$) to one Jupiter mass (1 M$_J$) by using the ZEUS hydrodynamics
code. We determine the gas flow pattern, and the accretion and migration rates
of the planet. The planet is assumed to be in a fixed circular orbit about the
central star. It is also assumed to be able to accrete gas without expansion on
the scale of its Roche radius. Only planets with masses $M \gsim 0.1$ M$_J$
produce significant perturbations in the disc's surface density. The flow
within the Roche lobe of the planet is fully three-dimensional. Gas streams
generally enter the Roche lobe close to the disc midplane, but produce much
weaker shocks than the streams in two-dimensional models. The streams supply
material to a circumplanetary disc that rotates in the same sense as the
planet's orbit. Much of the mass supply to the circumplanetary disc comes from
non-coplanar flow. The accretion rate peaks with a planet mass of approximately
0.1 M$_J$ and is highly efficient, occurring at the local viscous rate. The
migration timescales for planets of mass less than 0.1 M$_J$, based on torques
from disc material outside the planets' Roche lobes, are in excellent agreement
with the linear theory of Type I (non-gap) migration for three-dimensional
discs. The transition from Type I to Type II (gap) migration is smooth, with
changes in migration times of about a factor of 2. Starting with a core which
can undergo runaway growth, a planet can gain up to a few M$_J$ with little
migration. Planets with final masses of order 10 M$_J$ would undergo large
migration, which makes formation and survival difficult.


title: Time resolved spectroscopy of the variable brown dwarf Kelu-1

abstract:
  We report the results of observations designed to investigate the
spectroscopic signatures of dust clouds on the L2 brown dwarf Kelu-1. Time
resolved medium resolution spectra show no significant evidence of variability
in the dust sensitive TiO, CrH and FeH bandheads on the timescale of 1--24
hours. We do however report periodic variability in the psuedo-equivelent width
of H-alpha consistent with the 1.8 hour rotation period previously reported for
this object Clarke, Tinney & Tolley (2002). Near-contemporaneous I-band
photometry shows evidence for non-periodic variability at the level of 2%.


title:
Measuring the Oblateness and Rotation of Transiting Extrasolar Giant
  Planets

abstract:
  We investigate the prospects for characterizing extrasolar giant planets by
measuring planetary oblateness from transit photometry and inferring planetary
rotational periods. The rotation rates of planets in the solar system vary
widely, reflecting the planets' diverse formational and evolutionary histories.
A measured oblateness, assumed composition, and equation of state yields a
rotation rate from the Darwin-Radau relation. The lightcurve of a transiting
oblate planet should differ significantly from that of a spherical one with the
same cross-sectional area under identical stellar and orbital conditions.
However, if the stellar and orbital parameters are not known a priori, fitting
for them allows changes in the stellar radius, planetary radius, impact
parameter, and stellar limb darkening parameters to mimic the transit signature
of an oblate planet, diminishing the oblateness signature. Thus even if
HD209458b had an oblateness of 0.1 instead of our predicted 0.003, it would
introduce a detectable departure from a model spherical lightcurve at the level
of only one part in 10^5. Planets with nonzero obliquity break this degeneracy
because their ingress lightcurve is asymmetric relative to that from egress,
and their best-case detectability is of order 10^{-4}. However, the measured
rotation rate for these objects is non-unique due to degeneracy between
obliquity and oblateness and the unknown component of obliquity along the line
of sight. Detectability of oblateness is maximized for planets transiting near
an impact parameter of 0.7 regardless of obliquity. Future measurements of
oblateness will be challenging because the signal is near the photometric
limits of current hardware and inherent stellar noise levels.