title:
Concordance between the Dynamics of Satellite Galaxies in the 2dFGRS and
  Lambda-CDM

abstract:
  We compute the velocity dispersion profile, \sigmav(r_p), for satellites of
host galaxies in the Two Degree Field Galaxy Redshift Survey (2dFGRS) and in
the Lambda-CDM GIF simulation. We find 1345 hosts in the 2dFGRS with
luminosities in the range 0.5 L* < L < 5.5 L*, for which a total of 2475
satellite galaxies is obtained. The magnitudes of the galaxies in the GIF
simulation are converted to the b_J band pass, and hosts and satellites are
selected in the same manner as in the 2dFGRS. Of order 1200 hosts and 4100
satellites are found in the simulation. Overall, there is excellent agreement
between \sigmav(r_p) for the satellites in the 2dFGRS and the GIF simulation.
On large scales, \sigmav(r_p) decreases with projected radius, in good
agreement with the expectations of a CDM universe. Further, there is a marked
dependence of \sigmav(r_p) on both the host spectral type and the host
luminosity. In particular, \sigmav(r_p) has a substantially higher amplitude
and steeper slope for satellites of early-type hosts than it does for
satellites of late-type hosts. In addition, both the amplitude and slope of
\sigmav(r_p) increase with host luminosity. The velocity dispersion of
satellites located within small projected radii (r_p < 120 kpc) is only
marginally consistent with the local B-band Tully-Fisher relation, and is
fitted best by a relationship of the form \sigma_v \propto L^{0.45 \pm 0.10}.


title: Long-time evolution of magnetic fields in relativistic GRB shocks

abstract:
  We investigate the long-time evolution of magnetic fields generated by the
two-stream instability at ultra- and sub-relativistic astrophysical
collisionless shocks. Based on 3D PIC simulation results, we introduce a 2D toy
model of interacting current filaments. Within the framework of this model, we
demonstrate that the field correlation scale in the region far downstream the
shock grows nearly as the light crossing time, lambda(t) ~ ct, thus making the
diffusive field dissipation inefficient. The obtained theoretical scaling is
tested using numerical PIC simulations. This result extends our understanding
of the structure of collisionless shocks in gamma-ray bursts and other
astrophysical objects.


title:
Reappraising the Spite Lithium Plateau: Extremely Thin and Marginally
  Consistent with WMAP

abstract:
  The lithium abundance in 62 halo dwarfs is determined from accurate
equivalent widths reported in the literature and an improved infrared flux
method (IRFM) temperature scale. The Li abundance of 41 plateau stars (those
with Teff > 6000 K) is found to be independent of temperature and metallicity,
with a star-to-star scatter of only 0.06 dex over a broad range of temperatures
(6000 K < Teff < 6800 K) and metallicities (-3.4 < [Fe/H] < -1), thus imposing
stringent constraints on depletion by mixing and production by Galactic
chemical evolution. We find a mean Li plateau abundance of A(Li) = 2.37 dex
(7Li/H = 2.34 X 10^{-10}), which, considering errors of the order of 0.1 dex in
the absolute abundance scale, is just in borderline agreement with the
constraints imposed by the theory of primordial nucleosynthesis and WMAP data
(2.51 < A(Li)[WMAP] < 2.66 dex).


title: Discovery of the Neutron Star Spin Frequency in EXO 0748-676

abstract:
  We report the results of a search for burst oscillations during thermonuclear
X-ray bursts from the low mass X-ray binary (LMXB) EXO 0748-676. With the
proportional counter array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE)
we detected a 45 Hz oscillation in the average power spectrum of 38
thermonuclear X-ray bursts from this source. We computed power spectra with 1
Hz frequency resolution for both the rising and decaying portions of 38 X-ray
bursts from the public RXTE archive. We averaged the 1 Hz power spectra and
detected a significant signal at 45 Hz in the decaying phases of the bursts.
The signal is detected at a significance level of 4 x 10^-8. No similar signal
was detected in the rising intervals. A fit to the oscillation peak at 0.25 Hz
resolution gives a frequency of 44.7 +/- 0.06 Hz and an oscillation quality
factor of Q = 80 +/- 18. The average signal amplitude is 3% (rms). The
detection of 45 Hz burst oscillations from EXO 0748-676 provides compelling
evidence that this is the neutron star spin frequency in this system. We use
the inferred spin frequency to model the widths of absorption lines from the
neutron star surface and show that the widths of the absorption lines from EXO
0748-676 recently reported by Cottam et al. are consistent with a 45 Hz spin
frequency as long as the neutron star radius is in the range from about 9.5-15
km. With a known spin frequency, precise modelling of the line profiles from
EXO 0748-676 holds great promise for constraining the dense matter equation of
state.


title: Probing Spectral Line Gradients Beyond One Effective Radius in NGC 3610

abstract:
  The outer region (0.75--1.25 r_e in the B-band) of the merger-remnant
elliptical NGC 3610 is studied using extremely high signal to noise Keck
spectra, with a supplementary spectrum of the galaxy center. Stellar population
parameters -- age, [Z/H], [$\alpha$/Fe] -- are measured in several apertures
along the slit. Using the multi-index simultaneous fitting method of Proctor et
al. (2004), no significant stellar population gradients are detected in the
outer parts of the galaxy. The overall gradients relative to the galaxy center
are consistent with those found in many other early-type galaxies, though the
metallicity gradient is much steeper than would be expected if NGC 3610 formed
in a major merger event. Standard analysis methods using the H$\beta$ index are
found to produce spurious radially variable gradients.


title: Bayesian Adaptive Exploration

abstract:
  I describe a framework for adaptive scientific exploration based on iterating
an Observation--Inference--Design cycle that allows adjustment of hypotheses
and observing protocols in response to the results of observation on-the-fly,
as data are gathered. The framework uses a unified Bayesian methodology for the
inference and design stages: Bayesian inference to quantify what we have
learned from the available data and predict future data, and Bayesian decision
theory to identify which new observations would teach us the most. When the
goal of the experiment is simply to make inferences, the framework identifies a
computationally efficient iterative ``maximum entropy sampling'' strategy as
the optimal strategy in settings where the noise statistics are independent of
signal properties. Results of applying the method to two ``toy'' problems with
simulated data--measuring the orbit of an extrasolar planet, and locating a
hidden one-dimensional object--show the approach can significantly improve
observational efficiency in settings that have well-defined nonlinear models. I
conclude with a list of open issues that must be addressed to make Bayesian
adaptive exploration a practical and reliable tool for optimizing scientific
exploration.


title:
Accounting for Source Uncertainties in Analyses of Astronomical Survey
  Data

abstract:
  I discuss an issue arising in analyzing data from astronomical surveys:
accounting for measurement uncertainties in the properties of individual
sources detected in a survey when making inferences about the entire population
of sources. Source uncertainties require the analyst to introduce unknown
``incidental'' parameters for each source. The number of parameters thus grows
with the size of the sample, and standard theorems guaranteeing asymptotic
convergence of maximum likelihood estimates fail in such settings. From the
Bayesian point of view, the missing ingredient in such analyses is accounting
for the volume in the incidental parameter space via marginalization. I use
simple simulations, motivated by modeling the distribution of trans-Neptunian
objects surveyed in the outer solar system, to study the effects of source
uncertainties on inferences. The simulations show that current non-Bayesian
methods for handling source uncertainties (ignoring them, or using an ad hoc
incidental parameter integration) produce incorrect inferences, with errors
that grow more severe with increasing sample size. In contrast, accounting for
source uncertainty via marginalization leads to sound inferences for any sample
size.


title: Fourier transform method for imaging atmospheric Cherenkov telescopes

abstract:
  We propose Fourier transform (FT) method for processing images of extensive
air showers (EAS) detected by imaging atmospheric Cherenkov telescopes (IACT)
used in the very high energy (VHE) gamma-ray astronomy. The method is based on
the discrete Fourier transforms (DFT) on compact Lie groups, and the use of
continuous extension of the inverse discrete transforms to approximate the
discrete EAS images by continuous EAS brightness distribution functions. Here
we describe the FT-method in case of SU(3) group. It allows practical
realization of the DFT technique for functions sampled on hexagonal symmetry
grids. The proposed method can also be implemented in case of IACT cameras with
grids of rectangular symmetry by using the DFT on the SU(2)xSU(2) group. The
proposed FT-method is applied to the Monte-Carlo simulated bank of TeV proton
and gamma-ray EAS images for a stand-alone telescope. Comparing between the
FT-method and the currently used standard method shows that the FT technique
allows a better and systematic enhancement of the gamma-ray signal. The
relative difference between these two methods becomes more profound especially
for `photon poor' images. It suggests that the EAS detection thresholds of
IACTs could be effectively reduced with the use of FT technique. This
prediction is further supported by a significant noise suppression capability
of the method using simple low-pass filters in the image frequency domain. The
FT-method allows very deep `tail' (and `height') image cuts, differentiation of
images, operations in the image frequency domain, etc., that can be used for
development of new effective parameters for the EAS image processing.


title: Spectral Classification Beyond M

abstract:
  Significant populations of field L and T dwarfs are now known, and we
anticipate the discovery of even cooler dwarfs by Spitzer and ground-based
infrared surveys. However, as the number of known L and T dwarfs increases so
does the range in their observational properties, and difficulties have arisen
in interpreting the observations. Although modellers have made significant
advances, the complexity of the very low temperature, high pressure,
photospheres means that problems remain such as the treatment of grain
condensation as well as incomplete and non-equilibrium molecular chemistry.
Also, there are several parameters which control the observed spectral energy
distribution - effective temperature, grain sedimentation efficiency,
metallicity and gravity - and their effects are not well understood. In this
paper, based on a splinter session, we discuss classification schemes for L and
T dwarfs, their dependency on wavelength, and the effects of the parameters
T_eff, f_sed, [m/H] and log g on optical and infrared spectra. We will discuss
the various hypotheses that have been presented for the transition from the
dusty L types to the clear atmosphere T types. We conclude with a brief
discussion of the spectral class beyond T. Authors of each Section are
identified by their initials.


title: Gamma-Ray Burst Dust Echoes Revisited: Expectations at Early Times

abstract:
  Gamma-ray burst (GRB) dust echoes were first proposed as an alternative
explanation for the supernova-like (SN-like) components to the afterglows of
GRB 980326 and GRB 970228. However, the spectroscopic identification of Type Ic
SN 2003dh associated with GRB 030329, as well as the identification of SN-like
components to the afterglows of other GRBs, appears to have confirmed the
GRB/SN paradigm. However, the likely progenitors of Type Ic SNe are Wolf-Rayet
WC stars, and late-type WC stars have been observed to be surrounded by dust,
at a distance of 10^14 -- 10^15 cm from the star. Consequently, we revisit the
possibility of GRB dust echoes, not on a timescale of weeks after the burst but
on a timescale of minutes to hours. We find that if the optical flash is
sufficiently bright and the jet sufficiently wide, GRB afterglows may be
accompanied by chromatic variations on this timescale. From these signatures,
such model parameters as the inner radius of the dust distribution, the initial
opening angle of the jet, etc., may be deduced. With rapid and regular
localizations of GRBs by HETE-2, Integral, and now Swift, and new and improved
robotic telescope systems, these early-time GRB dust echoes may soon be
detected. We describe one such robotic telescope system, called PROMPT, that
the University of North Carolina at Chapel Hill is building at the Cerro Tololo
Inter-American Observatory in greater detail.


title: The Zone of Avoidance: Optical Compared to Near-Infrared Searches

abstract:
  Galaxies uncovered in the Zone of Avoidance (ZOA) with deep optical searches
are compared to the distribution of objects in the 2MASS Extended Source
Catalog (2MASX). While the galaxy density of optical surveys is strongly
correlated to the dust content, and become ineffective in uncovering the galaxy
distribution at A_B > 3.0 mag, this effect is much less severe in the NIR.
Galaxies can be identified in 2MASS at optical extinction layers of over 10mag.
However, star density has been found to be the dominant limiting factor in the
NIR in the wider Galactic Bulge region (see Fig. 4) where optical surveys still
do quite well.
  Systematic positional offsets have also been found between objects in the
2MASX and the optical ZOA as well as other galaxy catalogs. These seem to have
their origin in the astrometric reference frame used by these surveys as well
as different fitting algorithms when determining positions (details are given
in the Appendix). The astrometric offsets between 2MASX and more recent galaxy
catalogs (or on the Digitized Sky Survey remeasured positions) are of the order
of 1 - 1.5 arcsec, comparable to the relative dispersion in positions between
these surveys. Still, it is advisable to take this effect into account when
combining galaxies from different catalogs for observational purposes.


title: H1517+656: the Birth of a BL Lac Object?

abstract:
  H1517+656 is an unusual source, even for a BL Lac object. It is one of the
most luminous BL Lacs known, with extreme emission properties at radio,
optical, and X-ray frequencies. Furthermore, in our WFPC2 snapshot survey we
discovered a series of peculiar arcs describing a 2.4 arcsec radius ring
surrounding the source. This paper describes follow-up observations with
additional WFPC2 bands and the STIS longpass filter, which have revealed this
structure to be the remnants of a very recent galaxy merger. Population
synthesis modelling has shown that regions of the arcs have stellar populations
with age < 20 Myrs. Additionally, the circularity of the arcs indicates that
the plane of the collision and hence accretion is very close to the plane of
the sky. Given that BL Lac jets are thought to be aligned with the line of
sight, this observation may provide a direct link between the transfer of
angular momentum in an interaction and the generation of a radio source.


title:
L & M band infrared studies of V4332 Sagittarii - detection of the
  water-ice absorption band at 3.05 microns and the CO fundamental band in
  emission

abstract:
  L and M band observations of the nova-like variable V4332 Sgr are presented.
Two significant results are obtained viz. the unusual detection of water ice at
3.05 microns and the fundamental band of 12CO at 4.67 microns in emission. The
ice feature is a first detection in a nova-like variable while the CO emission
is rarely seen in novae. These results, when considered together with other
existing data, imply that V4332 Sgr could be a young object surrounded by a
circumstellar disc containing gas, dust and ice. The reason for a nova-like
outburst to occur in such a system is unclear. But since planets are believed
to form in such disks, it appears plausible that the enigmatic outburst of
V4332 Sgr could be due to a planetary infall. We also give a more reliable
estimate for an epoch of dust formation around V4332 Sgr which appears to have
taken place rather late in 1999 - nearly five years after its outburst.


title:
Evolution of the Dependence of Rest-frame Color and Morphology
  Distribution on Stellar Mass for Galaxies in the Hubble Deep Field North

abstract:
  Using the Subaru very deep K'-band imaging and HST WFPC2/NICMOS archival data
of the Hubble Deep Field North, we investigate the evolution of the stellar
mass, color, morphology of galaxies to z ~ 3. We mainly examine the rest-frame
U-V color distribution of galaxies as a function of stellar mass. At 0.3<z<2,
galaxies seem to be divided into the two populations at around the stellar mass
of ~5x10^9 M_solar. The low-mass galaxies have relatively bluer rest U-V color
and their color does not show clear correlation with stellar mass over the
range of 10^8-5x10^9 M_solar. On the other hand, at higher mass, the more
massive galaxies tend to have the redder U-V color. The average U-V color of
the low-mass galaxies becomes bluer gradually with redshift, from U-V ~ 0.2 at
z ~ 0.5 to U-V ~ -0.2 at z ~ 2. On the contrary, the correlation between the
stellar mass and rest U-V color of the high-mass population does not seem to
change significantly between z ~ 0.3 and z ~ 2. At z>2, it is seen that more
massive galaxies tend to have redder U-V color over the range of 10^9-10^10
M_solar. These results suggests that the star formation history of galaxies
depends on their stellar mass very much. The low-mass population is likely to
have relatively long star formation timescale. At the stellar mass larger than
~5x10^9 M_solar, there must be some mechanisms which suppress the star
formation in galaxies at 0<z<2.


title:
Evidence for nucleosynthesis in supernova $\gamma$-process: Universal
  scaling on p-nuclei

abstract:
  With analyzing the solar system abundance, we have found two universal
scaling laws concerning the p- and s-nuclei. They indicate that the
gamma-process in supernova (SN) explosions is the most promising origin of the
p-nuclei that has been discussed with many possible nuclear reactions and sites
for about fifty years. In addition the scalings provide new concepts: an
universality of the gamma-process and a new nuclear cosmochronometer. We have
carried out gamma-process nucleosynthesis calculations for typical
core-collapse SN explosion models and the results satisfy the observed
scalings.


title: Light Curve Models of Supernovae and X-ray spectra of Supernova Remnants

abstract:
  We compare parameters of well-observed type II SN1999em derived by M.Hamuy
and D.Nadyozhin based on Litvinova-Nadyozhin (1985) analytic fits with those
found from the simulations with our radiative hydro code Stella. The difference
of SN parameters is quite large for the long distance scale. The same code
applied to models of SN1993J allows us to estimate systematic errors of
extracting foreground extinction toward SN1993J suggested by Clocchiatti et al.
(1995). A new implicit two-temperature hydro code code Supremna is introduced
which self-consistently takes into account the kinetics of ionization, electron
thermal conduction, and radiative losses for predicting X-ray spectra of young
supernova remnants such as Tycho and Kepler.


title: Foreground contributions to the Cosmic Microwave Background

abstract:
  A detailed search has been made for evidence of foreground contributions to
the Cosmic Microwave Background (CMB) WMAP, such foregrounds being related to
our Galaxy. We find remarkable results. On the largest angular scales we find
significant differences between the power in the fluctuations for positive and
negative Galactic latitudes and between the four Galactic Quadrants. There are
also differences between the power spectrum at latitudes within 10 deg of the
Plane and at higher latitudes. The `slope' of the power spectrum has similar
variations.
  In an effort to find the origin of these Galactic-style effects we have
examined the evidence from Galactic gamma rays, specifically from the EGRET
instrument. A correlation is found between gamma ray intensities and the CMB
and other cosmic ray indicators.
  Most of the large scale Galactic asymmetries (eg north, south difference and
Quadrant variations) have analogues in cosmic ray asymmetries and also in some
other Galactic properties, such as the column density of gas. Thus, it is
possible to hypothesise on direct cosmic ray-induced contributions, although it
may be that cosmic rays are simply the indicators of Galactic `conditions'
which are influencing the residual CMB fluctuations.
  Irrespective of the actual cause of the correlations we have endeavoured to
extrapolate to the situation where the residual foreground is minimised. The
effect on the usually-derived cosmological properties - universal matter
content, ionization, the tensor contribution, tilt and curvature - is briefly
examined.


title:
The ultraviolet and optical spectra of luminous B-type stars in the
  Small Magellanic Cloud

abstract:
  We present ultraviolet spectra from the Space Telescope Imaging Spectrograph
(STIS) of 12 early B-type stars in the Small Magellanic Cloud (SMC), comprising
9 supergiants and 3 giants. A morphological comparison with Galactic analogues
is made using archival data from the International Ultraviolet Explorer (IUE).
In general, the intensity of the P Cygni emission in the UV resonance lines is
greater, and seen to later spectral types, in the Galactic spectra than in
their metal-deficient SMC counterparts; we attribute these effects as most
likely arising from weaker stellar winds in the SMC targets, as predicted by
radiatively driven wind theory.
  We also include unpublished STIS observations of two late O-type stars in the
SMC. In combination with the B-type observations, and published O-type data, we
now have an extensive ultraviolet spectral library of metal-deficient stars, of
use in the study of unresolved starbursts and high redshift, star-forming
galaxies. In this context, we present empirical measurements for the B-type
spectra of the new `1978 index' suggested by Rix et al. as a probe of
metallicity in such systems.


title:
Is the negative vacuum energy around galaxies a possible candidate for
  dark matter?

abstract:
  In this short communication we point out to the possibility that the clouds
of the negative vacuum energy around galaxies may have the same effect as dark
matter. These clouds amplify the force acting on the baryonic matter around
galaxies changing their dynamical and kinematical properties. Inserting the
density of the baryonic matter into field equations of the cosmic quaternionic
field for the present time yields the negative cosmological constant which is
approximately equal to the density of the baryonic matter of galaxies. Due to
the effect of the negative vacuum energy on moving cosmical objects the
effective total masses of galaxies assume several times larger values as their
baryonic masses.


title: Diffuse radio emission from the Intracluster medium

abstract:
  An important aspect of the radio emission from galaxy clusters is represented
by the diffuse radio sources associated with the intracluster medium: radio
halos, relics and mini-halos. The radio halos and relics are indicators of
cluster mergers, whereas mini-halos are detected at the center of cooling core
clusters. SKA will dramatically improve the knowledge of these sources, thanks
to the detection of new objects, and to detailed studies of their spectra and
polarized emission. SKA will also provide the opportunity to investigate the
presence of halos produced by radiation scattered by a powerful radio galaxy at
the cluster centers.


title:
The faint HI environment of galaxies: a laboratory for testing galaxy
  formation

abstract:
  The SKA is a unique instrument to open a window on many aspects of galaxy
formation and evolution which can be examined in our Local Universe. Here I
will focus on the outermost regions of galaxies which can be observed with
sufficient sensitivity and resolution at 21-cm as to enlighten the interplay
between galaxies and the intergalactic gas, the competing race between the
local dark matter gravity and the external ionizing radiation field. Tracing
the gas distribution out to large galactocentric radii will be complementary to
QSO's Ly$\alpha$ absorption studies for understanding the evolution of the dark
and visible matter of the Universe.


title: Mini High Velocity Clouds

abstract:
  Neutral hydrogen mapping of several small, very low column density High
Velocity Clouds (HVC), using the Arecibo telescope, is reported. Some were
found serendipitously superimposed at distinct velocities on largerHVCs; others
were found to comprise the four most isolated low column density sources in the
observations of Lockman et al. but proved to be individually much smaller than
the Green Bank 140 Foot telescope beam. We call these clouds ``mini-HVC'' to
distinguish them from the larger and denser Compact High Velocity Clouds
(CHVC). Peak column densities are typically a few X 10^18 cm^-2 averaged over
the Arecibo 3.2' beam, and diameters to our detection limit ~ 10^18 cm^-2 range
from 9' to 35'. These column densities and angular diameters overlap with those
for CHVC, but are typically smaller. We consider three possiblities: (1) that
most mini-HVC are related to the Magellanic Stream, (2) that most mini-HVC are
part of M31's retinue of CHVC, or (3) that the mini-HVC are simply the low
column density tail of the distribution of CHVC. None of these possibilities
can be rejected as yet, given the selection biases in our sample. We also
discuss controversies about the amount of ionized hydrogen in CHVC and
mini-HVC, which may be mainly ionized, and the implications of these small
clouds for Lyman Limit Systems.


title: Gamma-Ray Constraint on Galactic Positron Production by MeV Dark Matter

abstract:
  The Galactic positrons, as observed by their annihilation gamma-ray line at
0.511 MeV, are difficult to account for with astrophysical sources. It has been
proposed that they are produced instead by dark matter annihilation or decay in
the inner Galactic halo. To avoid other constraints, these processes are
required to occur "invisibly," such that the eventual positron annihilation is
the only detectable signal. However, electromagnetic radiative corrections to
these processes inevitably produce real gamma rays (``internal
bremsstrahlung"); this emission violates COMPTEL and EGRET constraints unless
the dark matter mass is less than about 20 MeV.


title:
Evolution of self-gravitating magnetized disks. II- Interaction between
  MHD turbulence and gravitational instabilities

abstract:
  We present 3D magnetohydrodynamic (MHD) numerical simulations of the
evolution of self--gravitating and weakly magnetized disks with an adiabatic
equation of state. Such disks are subject to the development of both the
magnetorotational and gravitational instabilities, which transport angular
momentum outward. As in previous studies, our hydrodynamical simulations show
the growth of strong m=2 spiral structure. This spiral disturbance drives
matter toward the central object and disappears when the Toomre parameter Q has
increased well above unity. When a weak magnetic field is present as well, the
magnetorotational instability grows and leads to turbulence. In that case, the
strength of the gravitational stress tensor is lowered by a factor of about~2
compared to the hydrodynamical run and oscillates periodically, reaching very
small values at its minimum. We attribute this behavior to the presence of a
second spiral mode with higher pattern speed than the one which dominates in
the hydrodynamical simulations. It is apparently excited by the high frequency
motions associated with MHD turbulence. The nonlinear coupling between these
two spiral modes gives rise to a stress tensor that oscillates with a frequency
which is a combination of the frequencies of each of the modes. This
interaction between MHD turbulence and gravitational instabilities therefore
results in a smaller mass accretion rate onto the central object.


title:
Scanning strategy for mapping the Cosmic Microwave Background
  anisotropies with Planck

abstract:
  We present simulations of different scanning strategies for the Planck
satellite. We review the properties of slow- and fast-precession strategies in
terms of uniformity of the integration time on the sky, the presence of
low-redundancy areas, the presence of deep fields, the presence of sharp
gradients in the integration time, and the redundancy of the scanning
directions. We also compare the results obtained when co-adding all detectors
of a given frequency channel. The slow-precession strategies allow a good
uniformity of the coverage, while providing two deep fields. On the other hand,
they do not allow a wide spread of the scan-crossing directions, which is a
feature of the fast-precession strategies. However, the latter suffer from many
sharp gradients and low-coverage areas on the sky. On the basis of these
results, the strategy for Planck can be selected to be a slow (e.g. 4
month-period) sinusoidal or cycloidal scanning.


title:
Particle decay during inflation: self-decay of inflaton quantum
  fluctuations during slow roll

abstract:
  Particle decay during inflation is studied by implementing a dynamical
renormalization group resummation combined with a small Delta expansion. Delta
measures the deviation from the scale invariant power spectrum and regulates
the infrared. In slow roll inflation, Delta is a simple function of the slow
roll parameters epsilon_V, eta_V.We find that quantum fluctuations can
self-decay as a consequence of the inflationary expansion through processes
which are forbidden in Minkowski space-time. We compute the self-decay of the
inflaton quantum fluctuations during slow roll inflation.For wavelengths deep
inside the Hubble radius the decay is enhanced by the emission of ultrasoft
collinear quanta, i.e. bremsstrahlung radiation of superhorizon quanta which
becomes the leading decay channel for physical wavelengths
H<<k_{ph}(eta)<<H/(eta_V-eps_V). The decay of short wavelength fluctuations
hastens as the physical wave vector approaches the horizon. Superhorizon
fluctuations decay with a power law eta^Gamma in conformal time where in terms
of the amplitude of curvature perturbations Delta^2_R, the scalar spectral
index n_s, the tensor to scalar ratio r and slow roll parameters: Gamma \simeq
[32 xi^2_V Delta^2_R]/ /(n_s-1+r/4)^2.The behavior of the growing mode
eta^{eta_V-epsilon_V+Gamma}/eta features an anomalous scaling dimension Gamma.
We discuss the implications of these results for scalar and tensor
perturbations and for non-gaussianities in the power spectrum. The recent WMAP
data suggests Gamma >3.6 10^{-9}.


title: Age-Dating of Starburst Galaxies

abstract:
  This review covers age-dating methods applied to young stellar populations in
starburst galaxies with ages of 10^8 yr and less. First, recent advances in
stellar modeling, both for the interior and the atmospheres, are discussed and
spectral lines and colors suitable for age-dating are identified. These age
indicators are then applied to single stellar populations, the simplest
building blocks of starbursts. More complex systems, such as luminous starburst
galaxies, are a challenge for chronometric measurements. The dust reddening,
metallicity, stellar initial mass function, and inhomogeneities of the
interstellar medium introduce degeneracies which are often hard to resolve.
Finally, some shortcomings in the stellar models are highlighted.


title: Disks Surviving the Radiation Pressure of Radio Pulsars

abstract:
  The radiation pressure of a radio pulsar does not necessarily disrupt a
surrounding disk. The position of the inner radius of a thin disk around a
neutron star can be estimated by comparing the electromagnetic energy density
generated by the neutron star with the kinetic energy density of the disk.
Inside the light cylinder, the near zone electromagnetic field is essentially
the dipole magnetic field, and the inner radius is the conventional Alfven
radius. Far outside the light cylinder, in the radiation zone, $E=B$ and the
electromagnetic energy density is $<S >/c \propto 1/r^2$ where $S$ is the
Poynting vector. Shvartsman (1970) argued that a stable equilibrium can not be
found in the radiative zone because the electromagnetic energy density
dominates over the kinetic energy density, with the relative strength of the
electromagnetic stresses increasing with radius. In order to check whether this
is true also near the light cylinder, we employ global electromagnetic field
solutions for rotating oblique magnetic dipoles (Deutsch 1955). Near the light
cylinder the electromagnetic energy density increases steeply enough with
decreasing $r$ to balance the kinetic energy density at a stable equilibrium.
The transition from the near zone to the radiation zone is broad. The radiation
pressure of the pulsar can not disrupt the disk for values of the inner radius
up to about twice the light cylinder radius if the rotation axis and the
magnetic axis are orthogonal. This allowed range beyond the light cylinder
extends much further for small inclination angles. We discuss implications of
this result for accretion driven millisecond pulsars and young neutron stars
with fallback disks.


title: Continuum Acceleration of Black Hole Winds

abstract:
  Motivated by recent observations of high-velocity, highly ionized winds in
several QSOs, models of purely continuum-driven winds launched from
approximately 200 GM_{BH}/c^2 are presented. Launching conditions are
investigated, as well as the observational signatures for a variety of initial
conditions and illuminating continua. While we verify that continuum-driven,
highly-ionized outflows reach the observed velocities for L/L_{Edd} >~ 1,
independent of the incident spectral shape, such winds are too highly ionized
to exhibit the observed absorption features when launched with an AGN continuum
(in fact, such winds are so ionized that they are driven primarily by electron
scattering). If the wind is instead illuminated with a blackbody continuum
originating from an optically thick shield, the gas is too weakly ionized and
does not produce high energy absorption features. If high-velocity,
high-ionization winds are truly launched from very near the black hole, such
winds must be launched under other conditions or via other processes; we
summarize some possibilities.


title:
Massive Star Formation in the W49 Giant Molecular Cloud: Implications
  for the Formation of Massive Star Clusters

abstract:
  We present results from JHKs imaging of the densest region of the W49
molecular cloud. In a recent paper (Alves & Homeier 2003), we reported the
detection of (previously unknown) massive stellar clusters in the well-known
giant radio HII region W49A, and here we continue our analysis. We use the
extensive line-of-sight extinction to isolate a population of objects
associated with W49A. We constrain the slope of the stellar luminosity function
by constructing an extinction-limited luminosity function, and use this to
obtain a mass function. We find no evidence for a top-heavy MF, and the slope
of the derived mass function is -1.6 \pm 0.3. We identify candidate massive
stars from our color-magnitude diagram, and we use these to estimate the
current total stellar mass of 5-7x10^4 M_sun in the region of the W49 molecular
cloud covered by our survey. Candidate ionizing stars for several ultra-compact
HII regions are detected, with many having multipe candidate sources. On the
global molecular cloud scale in W49, massive star formation apparently did not
proceed in a single concentrated burst, but in small groups, or subclusters.
This may be an essential physical description for star formation in what will
later be termed a 'massive star cluster'.


title: Is Dark Energy Dynamical? Prospects for an Answer

abstract:
  Recent data advances offer the exciting prospect of a first look at whether
dark energy has a dynamical equation of state or not. While formally theories
exist with a constant equation of state, they are nongeneric -- Einstein's
cosmological constant is a notable exception. So limits on the time variation,
w', directly tell us crucial physics. Two recent improvements in supernova data
from the Hubble Space Telescope allow important steps forward in constraining
the dynamics of dark energy, possessing the ability to exclude models with
w'\ga 1, if the universe truly has a cosmological constant. These data bring us
much closer to the ``systematics'' era, where further improvements will come
predominantly from more accurate, not merely more, observations. We examine the
possible gains and point out the complementary roles of space and ground based
observations in the near future. To achieve the leap to precision understanding
of dark energy in the next generation will require specially designed space
based measurements; we estimate the confidence level of detection of dynamics
(e.g. distinguishing between $w'=0$ and $w'=1$) will be ~1.8\sigma after the
ongoing generation, improving to more than 6.5\sigma in the dedicated space
generation.


title:
A Size of ~10 Mpc for the Ionized Bubbles at the End of Cosmic
  Reionization

abstract:
  The first galaxies to appear in the universe at redshifts z>20 created
ionized bubbles in the intergalactic medium of neutral hydrogen left over from
the Big-Bang. It is thought that the ionized bubbles grew with time, surrounded
clusters of dwarf galaxies and eventually overlapped quickly throughout the
universe over a narrow redshift interval near z~6. This event signaled the end
of the reionization epoch when the universe was a billion years old. Measuring
the hitherto unknown size distribution of the bubbles at their final overlap
phase is a focus of forthcoming observational programs aimed at highly
redshifted 21cm emission from atomic hydrogen. Here we show that the combined
constraints of cosmic variance and causality imply an observed bubble size at
the end of the overlap epoch of ~10 physical Mpc, and a scatter in the observed
redshift of overlap along different lines-of-sight of ~0.15. This scatter is
consistent with observational constraints from recent spectroscopic data on the
farthest known quasars. Our novel result implies that future radio experiments
should be tuned to a characteristic angular scale of ~0.5 degrees and have a
minimum frequency band-width of ~8 MHz for an optimal detection of 21cm flux
fluctuations near the end of reionization.


title:
Star-forming accretion flows and the low luminosity nuclei of giant
  elliptical galaxies

abstract:
  The luminosities of the centers of nearby elliptical galaxies are very low
compared to models of thin disc accretion to their black holes at the Bondi
rate, typically a few hundredths to a few tenths of a solar mass per year. This
has motivated models of inefficiently-radiated accretion that invoke weak
electron-ion thermal coupling, and/or inhibited accretion rates due to
convection or outflows. Here we point out that even if such processes are
operating, a significant fraction of the accreting gas is prevented from
reaching the central black hole because it condenses into stars in a
gravitationally unstable disc. Star formation occurs inside the Bondi radius
(typically ~100pc in giant ellipticals), but still relatively far from the
black hole in terms of Schwarzschild radii. Star formation depletes and heats
the gas disc, eventually leading to a marginally stable, but much reduced,
accretion flow to the black hole. We predict the presence of cold (~100K),
dusty gas discs, containing clustered H-alpha emission and occasional type II
supernovae, both resulting from the presence of massive stars. Star formation
accounts for several features of the M87 system: a thin disc, traced by H-alpha
emission, is observed on scales of about 100pc, with features reminiscent of
spiral arms and dust lanes; the star formation rate inferred from the intensity
of H-alpha emission is consistent with the Bondi accretion rate of the system.
Star formation may therefore help suppress accretion onto the central engines
of massive ellipticals. We also discuss some implications for the fueling of
the Galactic center and quasars.


title:
Shocked Molecular Gas in the Supernova Remnants W 28 and W 44:
  Near-infrared and millimeter-wave observations

abstract:
  High resolution millimeter-wave and near-infrared observations of the
supernova remnants W28 and W44 reveal extensive shocked molecular gas where
supernova blast waves are propagating into giant molecular clouds. New CO
observations were carried out with the IRAM 30-m and ARO 12-m telescopes, and
the near-infrared observations were with Palomar 200-inch telescope. The
near-infrared observations reveal shocked H2 emission from both supernova
remnants, showing intricate networks of filaments on arcsec scales, following
the bright ridges of the radio shells. The CO and CS linewidths, indicative of
the shock speed, are 20-30 km/s. Both the near-infrared and millimeter-wave
emission are attributed to shocks into gas with density >1e3 cm-3. Individual
shock structures are resolved in the H2 emission, with inferred edge-on shock
thickness ~1e17 cm, consistent with non-dissociative shocks into gas densities
of 1e3-1e4 cm-3. Bright 1720 MHz OH masers are located within the shocked H2
gas complexes and highlight only localized areas where the conditions for
masing are optimal. The Halpha and X-ray emission, have morphologies very
different from the radio. We find a detailed correlation of the radio and H2
emission for some long filaments, indicating cosmic ray acceleration or
re-acceleration due to the shocks into moderately dense gas. The different
morphologies of these two remnants at different wavelengths is explained by a
highly nonuniform structure for giant molecular clouds.


title: The Stellar Initial Mass Function in the Galactic Center

abstract:
  Massive stars define the upper limits of the star formation process, dominate
the energetics of their local environs, and significantly affect the chemical
evolution of galaxies. Their role in starburst galaxies and the early Universe
is likely to be important, but we still do not know the maximum mass that a
star can possess, i.e.``the upper mass cutoff.'' I will discuss results from a
program to measure the upper mass cutoff and IMF slope in the Galactic Center.
The results suggest that the IMF in the Galactic center may deviate
significantly from the Salpeter value, and that there may be an upper mass
cutoff to the initial mass function of $\sim$150 Msun.


title:
Is M82 X-1 Really An Intermediate-Mass Black Hole? X-ray Spectral and
  Timing Evidence

abstract:
  Ultra-luminous X-ray sources (ULXs) with apparent luminosities up to 100's of
times the Eddington luminosity for a neutron star have been discovered in
external galaxies. The existence of intermediate mass black holes has been
proposed to explain these sources. We present evidence for an intermediate-mass
black hole in the ULX M82 X-1 based on the spectral features and timing (QPO)
properties of the X-radiation from this source. We revisited XMM Newton and
RXTE data for M82 X-1 obtained in 2001 and 1997 for XMM and RXTE respectively.
We show for these observations that the source is either in transition or in a
high/soft state with photon spectral indices 2.1 and 2.7 respectively. We
confirm the early determination of the QPO frequency ~ 55 mHz in this source by
Strohmayer & Mushotzky and identify this as the low frequency QPO for the
source. We apply a new method to determine the BH mass of M82 X-1. The method
uses the index-QPO low frequency correlation that has been recently been
established in galactic black hole candidates GRS 1915+105, XTE J1550-564, 4U
1630-47 and others. Using scaling arguments and the correlation derived from
consideration of galactic BHs, we conclude that M82 X-1 is an intermediate BH
with a mass of the order of 1000 solar masses.


title:
A Wind analysis of an evolved Giant - FUSE and HST/STIS observations of
  an eclipsing Symbiotic Binary

abstract:
  A major outstanding problem in stellar astrophysics lies in understanding the
wind generation mechanism by which evolved giants lose mass. Phase-resolved
observations of eclipsing symbiotic binary systems, containing a mass-losing
giant and a hot white dwarf, are ideal for studying the wind generation
mechanisms in evolved stars. For such systems we use the orbital motion of the
dwarf through the giant's wind to provide a pencil-beam view through the
circumstellar gas. FUV observations can probe different layers of the wind in
absorption, permitting the derivation of the velocity profile and providing
valuable, spatially-resolved diagnostics of the cool wind.
  We present a series of FUSE and HST/STIS observations of two such systems and
discuss our findings. The velocity profiles, and by implication, wind
generation mechanisms for these giants are found to differ from those predicted
by commonly used parametrisations. The phasing of our observations allow us to
examine the density, temperature and velocity structure in the wind
acceleration region, as well as the composition of the outflowing material.


title: Models of the giant quadruple quasar SDSS J1004+4112

abstract:
  SDSS J1004+4112 is an unprecedented object. It looks much like several
quadruple quasars lensed by individual galaxies, only it is ~10 times larger,
and the lens is a cluster dominated by dark matter. We present free-form
reconstructions of the lens using recently-developed methods. The projected
cluster mass profile is consistent with being shallow, r^{-0.3...-0.5}, and can
be fit with either an NFW or a flat-cored 3 dimensional mass distribution.
However, we cannot rule out projected profiles as steep as r^{-1.3}. The
projected mass within 100 kpc is well-constrained as 5+/-1 10^{13}M_sun,
consistent with previous simpler models. Unlike previous work, however, we are
able to detect structures in the lens associated with cluster galaxies. We
estimate the mass associated with these galaxies, and show that they contribute
not more than about 10% of the total cluster mass within 100 kpc. Typical
galaxy masses, combined with typical luminosities yield a rough estimate of
their mass-to-light ratio, which is in the single digits. Finally, we discuss
implications for time-delay measurements in this system, and possibilities for
a partial Einstein ring.


title:
Early reionization by decaying particles and cosmic microwave background
  radiation

abstract:
  We study the reionization scenario in which ionizing UV photons emitted from
decaying particle, in addition to usual contributions from stars and quasars,
ionize the universe. It is found that the scenario is consistent with both the
first year data of the Wilkinson Microwave Anisotropy Probe and the fact that
the universe is not fully ionized until z \sim 6 as observed by Sloan Digital
Sky Survey. Likelihood analysis revealed that rather broad parameter space can
be chosen. This scenario will be discriminated by future observations,
especially by the EE polarization power spectrum of cosmic microwave background
radiation.


title: The Universality of Turbulence in Galactic Molecular Clouds

abstract:
  The universality of interstellar turbulence is examined from observed
structure functions of 27 giant molecular clouds and Monte Carlo modeling. We
show that the structure functions, dv=v0 l^gamma, derived from wide field
imaging of CO J=1-0 emission from individual clouds are described by a narrow
range in the scaling exponent, gamma, and the scaling coefficient, v0. The
similarity of turbulent structure functions emphasizes the universality of
turbulence in the molecular interstellar medium and accounts for the
cloud-to-cloud size-line width relationship initially identified by Larson
(1981). The degree of turbulence universality is quantified by Monte Carlo
simulations that reproduce the mean squared velocity residuals of the observed
cloud-to-cloud relationship. Upper limits to the variation of the scaling
amplitudes and exponents for molecular clouds are ~10-20%. The measured
invariance of turbulence for molecular clouds with vastly different sizes,
environments, and star formation activity suggests a common formation mechanism
such as converging turbulent flows within the diffuse ISM and a limited
contribution of energy from sources within the cloud with respect to large
scale driving mechanisms.


title:
Investigations of Lepton and Baryon Acceleration in Relativistic
  Astrophysical Shocks

abstract:
  Gamma-ray bursts are often the brightest objects in the sky during their
short life. Particle acceleration in trans-relativistic shocks, internal to the
main blastwave, may explain the early intensity peaks, and particle
acceleration in the main blastwave, as it slows from ultrarelativistic speeds
to the trans-relativistic range, may explain the afterglow. If the radiation
results from energetic leptons, how do leptons become energized? A nonlinear
relativistic Monte Carlo model was developed and used to study lepton and
baryon acceleration by parallel shocks in the trans-relativistic range. Given
the assumptions of this model, if the lepton and baryon number densities are of
the same order, leptons will always carry far less energy than baryons.
However, if the lepton density exceeds the baryon density by a factor of
300,000, the shock is modified primarily by leptons and energy equipartition
between leptons and baryons occurs. The lepton to baryon number density ratio
for energy equipartition is independent of shock speed over the
trans-relativistic range of Lorentz factors used in this study.


title:
Presupernova Evolution of Differentially Rotating Massive Stars
  Including Magnetic Fields

abstract:
  As a massive star evolves through multiple stages of nuclear burning on its
way to becoming a supernova, a complex, differentially rotating structure is
set up. Angular momentum is transported by a variety of classic instabilities,
and also by magnetic torques from fields generated by the differential
rotation. We present the first stellar evolution calculations to follow the
evolution of rotating massive stars including, at least approximately, all
these effects, magnetic and non-magnetic, from the zero-age main sequence until
the onset of iron-core collapse. The evolution and action of the magnetic
fields is as described by Spruit 2002 and a range of uncertain parameters is
explored. In general, we find that magnetic torques decrease the final rotation
rate of the collapsing iron core by about a factor of 30 to 50 when compared
with the non-magnetic counterparts. Angular momentum in that part of the
presupernova star destined to become a neutron star is an increasing function
of main sequence mass. That is, pulsars derived from more massive stars will
rotate faster and rotation will play a more dominant role in the star's
explosion. The final angular momentum of the core is determined - to within a
factor of two - by the time the star ignites carbon burning. For the lighter
stars studied, around 15 solar masses, we predict pulsar periods at birth near
15 ms, though a factor of two range is easily tolerated by the uncertainties.
Several mechanisms for additional braking in a young neutron star, especially
by fall back, are also explored.


title: New results from the Antarctic Muon And Neutrino Detector Array

abstract:
  We present recent results from the Antarctic Muon And Neutrino Detector Array
(AMANDA) on searches for high-energy neutrinos of extraterrestrial origin. We
have searched for a diffuse flux of neutrinos, neutrino point sources and
neutrinos from GRBs and from WIMP annihilations in the Sun or the center of the
Earth. We also present a preliminary result on the first energy spectrum above
a few TeV for atmospheric neutrinos.


title: Variation of the constants in the late and early universe

abstract:
  Recent key observational results on the variation of fine structure constant,
the proton to electron mass ratio and the gravitational constant are reviewed.
The necessity to substantiate the dark sector of cosmology and to test gravity
on astrophysical scales is also emphasized.


title:
On the influence of relativistic effects on X-ray variability of
  accreting black holes

abstract:
  X-rays produced by compact flares co-rotating with a Keplerian accretion disc
are modulated in time by Doppler effects. We improve on previous calculations
of these effects by considering recent models of intrinsic X-ray variability,
and compute the expected strength of the relativistic signal in current data of
Seyfert galaxies and black hole binaries. Such signals could clearly be seen
in, for example, recent XMM-Newton data from MCG-6-30-15, if indeed the X-rays
were produced by co-rotating flares concentrated toward the inner disc edge
around an extreme Kerr black hole. Lack of the signal in the data collected so
far gives support to models, where the X-ray sources in active galaxies do not
follow Keplerian orbits close to the black hole.


title: An overview of Cosmology

abstract:
  While purely philosophical in the early times, and still very speculative at
the beginning of the twentieth century, Cosmology has gradually entered into
the realm of experimental science over the past eighty years. It has raised
some fascinating questions like: is the Universe static or expanding ? How old
is it and what will be its future evolution ? Is it flat, open or closed ? Of
what type of matter is it composed ? How did structures like galaxies form ? In
this course, we will try to give an overview of these questions, and of the
partial answers that can be given today. In the first chapter, we will
introduce some fundamental concepts, in particular from General Relativity. In
the second chapter, we will apply these concepts to the real Universe and deal
with concrete results, observations, and testable predictions.


title: Tiny HI Clouds in the Local ISM

abstract:
  Very sensitive HI absorption spectra (tau RMS about 10^-4 over 1 km/s) toward
high latitude QSOs have revealed a population of tiny discrete features in the
diffuse ISM with peak tau of 0.1 - 2% and core line-widths corresponding to
temperatures as low as 20 K. Imaging detections confirm linear dimensions of a
few 1000 AU. We suggest these structures may be formed by the stellar winds of
intermediate mass stars. A more speculative origin might involve molecular
"dark matter".


title: Galaxy evolution in dense environments; a concise HI perspective

abstract:
  Observing the neutral Hydrogen in galaxy clusters provides crucial insights
in the physical processes that influence the evolution of gas-rich galaxies as
they migrate from the lower-density filaments through the cluster outskirts
into to the higher-density central regions. The morphology-density relation,
the Buther-Oemler effect, and the observed HI deficiencies in the central
regions of galaxy clusters suggest that infalling galaxies experience a strong
transformation of their morphologies, star formation rates, and gas content.
The physical mechanisms that trigger and govern these transformations may
depend strongly on environment. This contribution aims to illustrate that the
morphological and kinematic characteristics of the cold gas provide a sensitive
tool to determine which mechanisms dominate in which environments.


title:
Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: the Effects
  of Clouds, Gravity, and Effective Temperature

abstract:
  We present new JHKL'M' photometry on the MKO system for a large sample of L
and T dwarfs identified from SDSS and 2MASS and classified according to the
scheme of Geballe et al. (2002). We have compiled a sample of 105 L and T
dwarfs that are uniformly classified and measured on a single photometric
system. The scattered JHK spectral indices and colors of L dwarfs are likely
caused by variations in the altitudes, distributions, and thicknesses of
condensate clouds. Scatter in the H-K colors of late T dwarfs probably reflects
the sensitivity of the K-band flux to pressure induced H_2 opacity, which
itself is sensitive to surface gravity. The M' luminosities of late-T dwarfs
are 1.5-2.5 times fainter than predicted under conditions of chemical
equilibrium. We have computed L_bol and T_eff for 42 L and T dwarfs whose
trigonometric parallaxes have been measured. We find that T_eff ~ 1450 K for
types L7-T4, which supports recent models that attribute the changing JHK-band
luminosities and spectral features across the L-T transition to rapid changes
in the condensate clouds over a narrow range of T_eff. We compute T_eff =
600-750 K for 2MASS 0415-0935 (T9), which supplants Gl 570D as the coolest
known brown dwarf.


title:
Can Virialization Shocks be Detected Around Galaxy Clusters Through the
  Sunyaev-Zel'dovich Effect?

abstract:
  In cosmological structure formation models, massive non-linear objects in the
process of formation, such as galaxy clusters, are surrounded by large-scale
shocks at or around the expected virial radius. Direct observational evidence
for such virial shocks is currently lacking, but we show here that their
presence can be inferred from future, high resolution, high-sensitivity
observations of the Sunyaev-Zel'dovich (SZ) effect in galaxy clusters. We study
the detectability of virial shocks in mock SZ maps, using simple models of
cluster structure (gas density and temperature distributions) and noise
(background and foreground galaxy clusters projected along the line of sight,
as well as the cosmic microwave background anisotropies). We find that at an
angular resolution of 2'' and sensitivity of 10 micro K, expected to be reached
at ~ 100 GHz frequencies in a ~ 20 hr integration with the forthcoming ALMA
instrument, virial shocks associated with massive M ~ 10^15 M_Sun clusters will
stand out from the noise, and can be detected at high significance. More
generally, our results imply that the projected SZ surface brightness profile
in future, high-resolution experiments will provide sensitive constraints on
the density profile of cluster gas.


title: Observational constraints on the time-dependence of dark energy

abstract:
  One of the most important questions nowadays in physics concerns the nature
of the so-called dark energy. It is also a consensus among cosmologists that
such a question will not be answered on the basis only of observational data.
However, it is possible to diminish the range of possibilities for this dark
component by comparing different dark energy scenarios and finding which models
can be ruled out by current observations. In this paper, by asssuming three
distinct parametrizations for the low-redshift evolution of the dark energy
equation of state (EOS), we consider the possibility of discriminating between
evolving dark energy and $\Lambda$CDM models from a joint analysis involving
the most recent radio sources gravitational lensing sample, namely, the Cosmic
All Sky Survey (CLASS) statistical data and the recently published \emph{gold}
SNe Ia sample. It is shown that this particular combination of observational
data restricts considerably the dark energy parameter space, which enables
possible distinctions between time-dependent and constant EOS's.


title: The distribution of kHz QPO frequencies in Sco X-1

abstract:
  The frequencies of kHz Quasi-Periodic Oscillations in the bright Low-Mass
X-ray Binary Sco X-1 have been reported to appear preferentially in a 3:2
ratio. We show that a proper statistical analysis of those RXTE data upon which
the claim is based indicated a 2.4 sigma deviation from a constant distribution
in ratios. The analysis of a much larger RXTE/PCA dataset shows that there is
no sharp concentration around a 3:2 ratio, but that the ratios are broadly
distributed over the range 820-1150 Hz.


title: An Upper Bound on the Flux Ratio of rho CrB's Companion at 1.6um

abstract:
  We use high resolution infrared spectroscopy to investigate the 2001 report
by Gatewood and colleagues that rho CrB's candidate extrasolar planet companion
is really a low-mass star with mass 0.14+-0.05 Msun. We do not detect evidence
of such a companion; the upper bounds on the (companion/primary) flux ratio at
1.6 microns are less than 0.0024 and 0.005 at the 90 and 99% confidence levels,
respectively. Using the H-band mass-luminosity relationship calculated by
Baraffe and colleagues, the corresponding upper limits on the companion mass
are 0.11 and 0.15 Msun. Our results indicate that the infrared spectroscopic
technique can detect companions in binaries with flux ratios as low as 0.01 to
0.02.


title:
X-ray source overdensities in Chandra distant cluster fields: a new
  probe to map the cosmic tapestry?

abstract:
  The first systematic study of the serendipitous X-ray source density around
10 high z (0.24<z<1.2) clusters has been performed with Chandra. A factor ~2
overdensity has been found in 4 cluster fields, increasing to 11 the number of
known source overdensities around high z clusters. The result is statistically
highly significant (at >2 sigma per field, and >5 sigma overall) only on scales
8'X8' and peculiar to cluster fields. The blank field fluctuations, i.e. the
most sensitive measurements to date of the X-ray cosmic variance on this scale,
indicate variations within ~15-25% around the average value. The first marginal
evidence that these overdensities increase with cluster redshift is also
presented. We speculate that the most likely explanation for what has been
observed is that the x-ray sources are AGNs which trace filaments connected to
the clusters. Nevertheless other possible explanations such as an ``X-ray
Butcher-Oemler'' effect are not ruled out by present results. If the
association of the overdensities with large-scale structures and their positive
relation with cluster redshift is confirmed, these studies could represent a
new, direct, way of mapping the cosmic web and its parameters at high z.


title:
Time evolution of the stochastic linear bias of interacting galaxies on
  linear scales

abstract:
  We extend the time dependent bias model of Tegmark & Peebles (1998) to
predict the large-scale evolution of the stochastic linear bias of different
galaxy populations with respect to both the dark matter and each other. The
resulting model equations contain a general expression, coined the "interaction
term", accounting for the destruction or production of galaxies. This term may
be used to model couplings between different populations that lead to an
increase or decrease of the number of a galaxies belonging to a population,
e.g. passive evolution or merging processes. This is explored in detail using a
toy model. In particular, it is shown that the presence of such a coupling may
change the evolution of the bias parameter compared to an interaction-free
evolution. We argue that the observation of the evolution of the large-scale
bias and galaxy number density with wide-field surveys may be used to infer
fundamental interaction parameters between galaxy populations, possibly giving
an insight in their formation and evolution.


title: Black holes in galaxy mergers: The formation of red elliptical galaxies

abstract:
  We use hydrodynamical simulations to study the color transformations induced
by star formation and active galactic nuclei (AGN) during major mergers of
spiral galaxies. Our modeling accounts for radiative cooling, star formation,
and supernova feedback. Moreover, we include a treatment of accretion onto
supermassive black holes embedded in the nuclei of the merging galaxies. We
assume that a small fraction of the bolometric luminosity of an accreting black
hole couples thermally to surrounding gas, providing a feedback mechanism that
regulates its growth. The encounter and coalescence of the galaxies triggers
nuclear gas inflow which fuels both a powerful starburst and strong black hole
accretion. Comparing simulations with and without black holes, we show that AGN
feedback can quench star formation and accretion on a short
timescale,particularly in large galaxies where the black holes can drive
powerful winds once they become sufficiently massive. The color evolution of
the remnant differs markedly between mergers with and without central black
holes. Without AGN, gas-rich mergers lead to ellipticals which remain blue
owing to residual star formation, even after more than 7 Gyrs have elapsed. In
contrast, mergers with black holes produce ellipticals that redden much faster,
an effect that is more pronounced in massive remnants where a nearly complete
termination of star formation occurs, allowing them to redden to u-r ~ 2.3 in
less than one Gyr. AGN feedback may thus be required to explain the population
of extremely red massive early type-galaxies, and it appears to be an important
driver in generating the observed bimodal color distribution of galaxies in the
Local Universe.


title: Kinematics of the Ionized Halo of NGC 5775

abstract:
  Studies of the kinematics of gaseous halos in some spiral galaxies have shown
that the rotational velocity of the gas decreases with height above the
midplane (z). This vertical velocity gradient has been observed in both the
neutral and ionized components of halos. We present imaging Fabry-Perot Halpha
observations of the edge-on galaxy NGC 5775. These observations allow us to
study the variation in the rotation curve (and, to some extent, the radial
profile) of the ionized gas component as a function of z. We have used an
iterative technique to infer the major axis rotation curve from the ionized gas
observations as well as CO data. A preliminary analysis of position-velocity
(PV) diagrams parallel to the major axis implies the presence of a vertical
velocity gradient. The magnitude of this gradient is tentatively found to be ~2
km/s/arcsec, consistent with the results of Rand (2000) and Tullmann et al.
(2000).


title: The X-ray variability properties of PG quasars: XMM-Newton results

abstract:
  This paper presents preliminary results of a systematic study on the X-ray
spectral variability of PG quasars with XMM-Newton. We concentrate on those
objects, whose X-ray spectra are well fit in the framework of the ``double
Comptonization'' model. On short (<1000 seconds) timescales, variability
between the soft (E<2 keV) and the hard (E>2 keV) bands is uncorrelated. In the
two objects, for which observations at different epochs are available, spectral
variability in the soft X-ray regime is unveiled. Its timescale is constrained
in the range between ~1 week and ~1 year.


title:
Hubble Space Telescope and Ground-Based Observations of SN 1993J and SN
  1998S: CNO Processing in the Progenitors

abstract:
  Ground-based and Hubble Space Telescope observations are presented for SN
1993J and SN 1998S. SN 1998S shows strong, relatively narrow circumstellar
emission lines of N III-V and C III-IV, as well as broad lines from the ejecta.
Both the broad ultraviolet and optical lines in SN 1998S indicate an expansion
velocity of ~7,000 km/s. The broad emission components of Ly-alpha and Mg II
are strongly asymmetrical after day 72 past the explosion, and differ in shape
from H-alpha. Different models based on dust extinction from dust in the ejecta
or shock region, in combination with H-alpha from a circumstellar torus, are
discussed. It is concluded, however, that the double-peaked line profiles are
more likely to arise as a result of optical depth effects in the narrow, cool,
dense shell behind the reverse shock, than in a torus-like region. The
ultraviolet lines of SN 1993J are broad, with a box-like shape, coming from the
ejecta and a cool dense shell. The shapes of the lines are well fitted with a
shell with inner velocity ~7,000 km/s and outer velocity ~10,000 km/s. For both
SN 1993J and SN 1998S a strong nitrogen enrichment is found, with N/C~12.4 in
SN 1993J and N/C~6.0 in SN 1998S. From a compilation of all supernovae with
determined CNO ratios, we discuss the implications of these observations for
the structure of the progenitors of Type II supernovae.


title: Predicted Abundances of Carbon Compounds in Volcanic Gases on Io

abstract:
  We use chemical equilibrium calculations to model the speciation of carbon in
volcanic gases on Io. The calculations cover wide temperature (500-2000 K),
pressure (10^-8 to 10^+2 bars), and composition ranges (bulk O/S atomic ratios
\~0 to 3), which overlap the nominal conditions at Pele (1760 K, 0.01 bar, O/S
~ 1.5). Bulk C/S atomic ratios ranging from 10^-6 to 10^-1 in volcanic gases
are used with a nominal value of 10^-3 based upon upper limits from Voyager for
carbon in the Loki plume on Io. Carbon monoxide and CO2 are the two major
carbon gases under all conditions studied. Carbonyl sulfide and CS2 are orders
of magnitude less abundant. Consideration of different loss processes
(photolysis, condensation, kinetic reactions in the plume) indicates that
photolysis is probably the major loss process for all gases. Both CO and CO2
should be observable in volcanic plumes and in Io's atmosphere at abundances of
several hundred parts per million by volume for a bulk C/S ratio of 10^-3.


title: Relativistic Jets from Accretion Disks

abstract:
  The jets observed to emanate from many compact accreting objects may arise
from the twisting of a magnetic field threading a differentially rotating
accretion disk which acts to magnetically extract angular momentum and energy
from the disk. Two main regimes have been discussed, hydromagnetic jets, which
have a significant mass flux and have energy and angular momentum carried by
both matter and electromagnetic field and, Poynting jets, where the mass flux
is small and energy and angular momentum are carried predominantly by the
electromagnetic field. Here, we describe recent theoretical work on the
formation of relativistic Poynting jets from magnetized accretion disks.
Further, we describe new relativistic, fully-electromagnetic, particle-in-cell
simulations of the formation of jets from accretion disks. Analog Z-pinch
experiments may help to understand the origin of astrophysical jets.


title: The Secular Bar-Mode Instability in Rapidly Rotating Stars Revisited

abstract:
  Uniformly rotating, homogeneous, incompressible Maclaurin spheroids that spin
sufficiently rapidly are secularly unstable to nonaxisymmetric, bar-mode
perturbations when viscosity is present. The intuitive explanation is that
energy dissipation by viscosity can drive an unstable spheroid to a stable,
triaxial configuration of lower energy - a Jacobi ellipsoid. But what about
rapidly rotating compressible stars? Unlike incompressible stars, which contain
no internal energy and therefore immediately liberate all the energy dissipated
by viscosity, compressible stars have internal energy and can retain the
dissipated energy as internal heat. Now compressible stars that rotate
sufficiently rapidly and also manage to liberate this dissipated energy very
quickly are known to be unstable to bar-mode perturbations, like their
incompressible counterparts. But what is the situation for rapidly rotating
compressible stars that have very long cooling timescales, so that all the
energy dissipated by viscosity is retained as heat, whereby the total energy of
the star remains constant on a secular (viscous) evolution timescale? Are such
stars also unstable to the nonlinear growth of bar modes, or is the viscous
heating sufficient to cause them to expand, drive down the ratio of rotational
kinetic to gravitational potential energy T/|W| ~ 1/R, where R is the
equatorial radius, and turn off the instability before it gets underway? If the
instability still arises in such stars, at what rotation rate do they become
unstable, and to what final state do they evolve? We provide answers to these
questions in the context of the compressible ellipsoid model for rotating
stars. The results should serve as useful guides for numerical simulations in
3+1 dimensions for rotating stars containing viscosity.


title: On the Period Distribution of Close-In Extrasolar Giant Planets

abstract:
  Transit (TR) surveys for extrasolar planets have recently uncovered a
population of ``very hot Jupiters,'' planets with orbital periods of P< 3 d. At
first sight this may seem surprising, given that radial velocity (RV) surveys
have found a dearth of such planets, despite the fact that their sensitivity
increases with decreasing P. We examine the confrontation between RV and TR
survey results, paying particular attention to selection biases that favor
short-period planets in transit surveys. We demonstrate that, when such biases
and small-number statistics are properly taken into account, the period
distribution of planets found by RV and TR surveys are consistent at better
than the 1-sigma level. This consistency holds for a large range of reasonable
assumptions. In other words, there are not enough planets detected to robustly
conclude that the RV and TR short-period planet results are inconsistent.
Assuming a logarithmic distribution of periods, we find that the relative
frequency of very hot Jupiters (VHJ: P=1-3 d) to hot Jupiters (HJ: P=3-9 d) is
10-20%. Given an absolute frequency of HJ of ~1%, this implies that
approximately one star in ~500-1000 has a VHJ. We also note that VHJ and HJ
appear to be distinct in terms of their upper mass limit. We discuss the
implications of our results for planetary migration theories, as well as
present and future TR and RV surveys.


title:
An optical time delay for the double gravitational lens system FBQ
  0951+2635

abstract:
  We present optical R-band light curves of the double gravitationally lensed
quasar FBQ 0951+2635 from observations obtained at the Nordic Optical Telescope
between March 1999 and June 2001. A time delay of 16 +/- 2 days (1 sigma) is
determined from the light curves. New constraints on the lensing geometry are
provided by the position and ellipticity of the lensing galaxy. For a (Omega_m,
Omega_Lambda) = (0.3, 0.7) cosmology, the time delay yields a Hubble parameter
of H_0 = 60^{+9}_{-7} (random, 1 sigma) +/- 2 (systematic) km/s/Mpc for a
singular isothermal ellipsoid model and H_0 = 63^{+9}_{-7} (random, 1 sigma)
+/- 1 (systematic) km/s/Mpc for a constant mass-to-light ratio model. In both
models, the errors are mainly due to the time-delay uncertainties.
Non-parametric models yield H_0 = 64^{+9}_{-7} (random, 1 sigma) +/- 14
(systematic) km/s/Mpc.


title: Baryon Oscillations and Dark-Energy Constraints from Imaging Surveys

abstract:
  Baryonic oscillations in the galaxy power spectrum have been studied as a way
of probing dark-energy models. While most studies have focused on spectroscopic
surveys at high redshift, large multi-color imaging surveys have already been
planned for the near future. In view of this, we study the prospects for
measuring baryonic oscillations from angular statistics of galaxies binned
using photometric redshifts. We use the galaxy bispectrum in addition to the
power spectrum; this allows us to measure and marginalize over possibly complex
galaxy bias mechanisms to get robust cosmological constraints. In our parameter
estimation we allow for a weakly nonlinear biasing scheme that may evolve with
redshift by two bias parameters in each of ten redshift bins. We find that a
multi-color imaging survey that probes redshifts beyond one can give
interesting constraints on dark-energy parameters. In addition, the shape of
the primordial power spectrum can be measured to better accuracy than with the
CMB alone. We explore the impact of survey depth, area, and calibration errors
in the photometric redshifts on dark-energy constraints.


title: Nucleosynthesis in the Hot Convective Bubble in Core-Collapse Supernovae

abstract:
  As an explosion develops in the collapsed core of a massive star, neutrino
emission drives convection in a hot bubble of radiation, nucleons, and pairs
just outside a proto-neutron star. Shortly thereafter, neutrinos drive a
wind-like outflow from the neutron star. In both the convective bubble and the
early wind, weak interactions temporarily cause a proton excess (Ye > 0.5) to
develop in the ejected matter. This situation lasts for at least the first
second, and the approximately 0.05 - 0.1 solar masses that is ejected has an
unusual composition that may be important for nucleosynthesis. Using tracer
particles to follow the conditions in a two-dimensional model of a successful
supernova explosion calculated by Janka, Buras & Rampp (2003), we determine the
composition of this material. Most of it is helium and 56Ni. The rest is
relatively rare species produced by the decay of proton-rich isotopes unstable
to positron emission. In the absence of pronounced charged-current neutrino
capture, nuclear flow will be held up by long-lived waiting point nuclei in the
vicinity of 64Ge. The resulting abundance pattern can be modestly rich in a few
interesting rare isotopes like 45Sc, 49Ti, and 64Zn. The present calculations
imply yields that, when compared with the production of major species in the
rest of the supernova, are about those needed to account for the solar
abundance of 45Sc and 49Ti. Since the synthesis will be nearly the same in
stars of high and low metallicity, the primary production of these species may
have discernible signatures in the abundances of low metallicity stars. We also
discuss uncertainties in the nuclear physics and early supernova evolution to
which abundances of interesting nuclei are sensitive.


title:
An empirical initial-final mass relation from hot, massive white dwarfs
  in NGC 2168 (M35)

abstract:
  The relation between the zero-age main sequence mass of a star and its
white-dwarf remnant (the initial-final mass relation) is a powerful tool for
exploration of mass loss processes during stellar evolution. We present an
empirical derivation of the initial-final mass relation based on spectroscopic
analysis of seven massive white dwarfs in NGC 2168 (M35). Using an internally
consistent data set, we show that the resultant white dwarf mass increases
monotonically with progenitor mass for masses greater than 4 solar masses, one
of the first open clusters to show this trend. We also find two massive white
dwarfs foreground to the cluster that are otherwise consistent with cluster
membership. These white dwarfs can be explained as former cluster members
moving steadily away from the cluster at speeds of <~0.5 km/s since their
formation and may provide the first direct evidence of the loss of white dwarfs
from open clusters. Based on these data alone, we constrain the upper mass
limit of WD progenitors to be >=5.8 solar masses at the 90% confidence level
for a cluster age of 150 Myr.


title:
Absorption Line Study of Halo Gas in NGC 3067 Toward the Background
  Quasar 3C 232

abstract:
  We present new H I 21 cm absorption data and ultraviolet spectroscopy from
HST/STIS of the QSO/galaxy pair 3C 232/NGC 3067. The QSO sightline lies near
the minor axis and 1.8 arcmin (11 kpc) above the plane of NGC 3067, a nearby
luminous (cz = 1465 km/s, L = 0.5L*) starburst galaxy with a moderate star
formation rate of 1.4 Solar masses per year. The UV spectra show that the Si IV
and C IV doublets have the same three velocity components at cz = 1369, 1417,
and 1530 km/s found in Ca II H & K, Na I D, Mg I, Mg II, and Fe II, implying
that the low and high ionization gas are both found in three distinct absorbing
clouds (only the strongest component at 1420 km/s is detected in H I 21 cm).
The new Lyman alpha observation allows the first measurements of the spin and
kinetic temperatures of halo gas: T_s = 435 +/- 140 K and T_k/T_s ~ 1. However,
while a standard photoionization model can explain the low ions, the C IV and
Si IV are explained more easily as collisionally-ionized boundary layers of the
photoionized clouds. Due to their small inferred space velocity offsets (-260,
-130, and +170 km/s) relative to the nucleus of NGC 3067 and the spatial
coincidence of low and high ionization gas, we propose that these absorbers are
analogous to Galactic high velocity clouds (HVCs). A comparison of the NGC 3067
clouds and Galactic HVCs finds similar H I column densities, kinematics,
metallicities, spin temperatures, and inferred sizes. We find no compelling
evidence that any halo gas along this sightline is escaping the gravitational
potential of NGC 3067, despite its modest starburst.


title:
The pre-main sequence spectroscopic binary UZ Tau East: improved orbital
  parameters and accretion phase dependence

abstract:
  We present radial-velocity measurements obtained using high- and
intermediate-resolution spectroscopic observations of the classical T Tauri
star UZ Tau East obtained from 1994 to 1996. We also provide measurements of
H$\alpha$ equivalent widths and optical veiling. Combining our radial-velocity
data with those recently reported by Prato et al. (2002), we improve the
orbital elements for this spectroscopic binary. The orbital period is
18.979$\pm$0.007 days and the eccentricity is e=0.14. We find variability in
the H$_\alpha$ emission and veiling, signposts of accretion, but at periastron
passage the accretion is not as clearly enhanced as in the case of the binary
DQ Tau. The difference in the behaviour of these two binaries is consistent
with the hydrodynamical models of accretion from circumbinary disks because UZ
Tau East has lower eccentricity than DQ Tau. It seems that enhanced periastron
accretion may occur only in systems with very high eccentricity (e$>$0.5).


title: On the potassium-rotation connection in late-type Alpha Persei stars

abstract:
  We present measurements of the \ion{K}{i} $\lambda 7699$ line from spectra of
19 late-type members of the $\alpha$Persei cluster obtained with the
Intermediate Dispersion Spectrograph at the Isaac Newton Telescope. These stars
span a narrow range of $T_\mathrm{eff}$, from 5091 K to 4771 K, and a wide
range of $v \sin i$ values (9 $\mathrm{km s}^{-1}$--170 $\mathrm{km s}^{-1}$).
We find empirically that larger rotational broadening increases the equivalent
width of \ion{K}{i} $\lambda 7699$ linearly for $v \sin i$ values from 15
$\mathrm{km s}^{-1}$ to 75 $\mathrm{km s}^{-1}$. This correlation breaks down
for $v \sin i >$ 75 $\mathrm{km s}^{-1}$. After correction for this effect, we
show that the potassium line equivalent widths do not correlate with $v \sin
i$.}


title: Decay of the vacuum energy into CMB photons

abstract:
  We examine the possibility of the decay of the vacuum energy into cosmic
microwave background (CMB) photons. It is shown that observations of the
primordial density fluctuation spectrum put strong limits on the possible decay
rate. When photon creation due to the vacuum energy decay takes place, the
standard linear temperature dependence, T(z)=T_0(1+z), where T_0 is the present
CMB temperature, is modified. The decay is described by a generic temperature
dependence, T(z)=T_0(1+z)^{1-\beta}, of the CMB photons. A strong limit on the
maximum value of the decay rate is obtained by placing a maximum value on the
\beta parameter: \beta_{max}\approx 3\times 10^{-3}.


title: Formation of Nuclear Spirals in Barred Galaxies

abstract:
  We have performed smoothed particle hydrodynamics (SPH) simulations for the
response of the gaseous disk to the imposed moderately strong non-axisymmetric
potentials. The model galaxies are composed of the three stellar components
(disk, bulge and bar) and two dark ones (supermassive black hole and halo)
whose gravitational potentials are assumed to be invariant in time in the frame
corotating with the bar. We found that the torques alone generated by the
moderately strong bar that gives the maximum of tangential-to-radial force
ratio as $(F_{Tan}/F_{Rad})_{max}= 0.3$ are not sufficient to drive the gas
particles close to the center due to the barrier imposed by the inner Lindblad
resonances (ILRs). In order to transport the gas particles towards the nucleus
($r<100$ pc), a central supermassive black hole (SMBH) and high sound speed of
the gas are required to be present. The former is required to remove the inner
inner Lindblad resonance (IILR) that prevents gas inflow close to the nucleus,
while the latter provides favourable conditions for the gas particles to lose
their angular momentum and to spiral in. Our models that have no IILR show the
trailing nuclear spirals whose innermost parts reach close to the center in a
curling way when the gas sound speed is $ c_{s} \gtrsim 15$ km s$^{-1}$. They
resemble the symmetric two-armed nuclear spirals observed in the central
kiloparsec of spiral galaxies. We found that the symmetric two-armed nuclear
spirals are formed by the hydrodynamic spiral shocks caused by the
gravitational torque of the bar in the presence of a central SMBH that can
remove IILR when the sound speed of gas is high enough to drive a large amount
of gas inflow deep inside the ILR. However, the detailed morphology of nuclear
spirals depends on the sound speed of gas.


title:
Magnetic Field Amplification in Tycho and other Shell-type Supernova
  Remnants

abstract:
  It is shown that amplification of the magnetic field in supernova remnants
(SNRs) occurs in all six objects where morphological measurements are presently
available in the hard X-ray continuum at several keV. For the three
archetypical objects (SN 1006, Cas A and Tycho's SNR) to which nonlinear
time-dependent acceleration theory has been successfully applied up to now, the
global theoretical and the local observational field strengths agree very well,
suggesting in addition that all young SNRs exhibit the amplification effect as
a result of very efficient acceleration of nuclear cosmic rays (CRs) at the
outer shock. Since this appears to be empirically the case, we may reverse the
argument and consider field amplification as a measure of nuclear CR
acceleration and it has indeed been argued that acceleration in the amplified
fields allows the CR spectrum from SNRs to reach the knee in the spectrum or,
in special objects, even beyond. The above results are furthermore used to
investigate the time evolution of field amplification in young SNRs. Although
the uncertainties in the data do not allow precise conclusions regarding this
point, they rather clearly show that the ratio of the magnetic field energy
density and the kinetic energy density of gas flow into the shock is of the
order of a few percent if the shock speed is high enough V_s > 10^3 km/s, and
this ratio remains nearly constant during the SNR evolution. The escape of the
highest energy nuclear particles from their sources becomes progressively
important with age, reducing also the cutoff in the \pi^0 -decay gamma-ray
emission spectrum with time after the end of the sweep-up phase. Simultaneously
the leptonic gamma-ray channels will gain in relative importance with
increasing age of the sources.


title: Bondi Accretion in the Presence of Vorticity

abstract:
  The classical Bondi-Hoyle formula gives the accretion rate onto a point
particle of a gas with a uniform density and velocity. However, the Bondi-Hoyle
problem considers only gas with no net vorticity, while in a real astrophysical
situation accreting gas invariably has at least a small amount of vorticity. We
therefore consider the related case of accretion of gas with constant
vorticity, for the cases of both small and large vorticity. We confirm the
findings of earlier two dimensional simulations that even a small amount of
vorticity can substantially change both the accretion rate and the morphology
of the gas flow lines. We show that in three dimensions the resulting flow
field is non-axisymmetric and time dependent. The reduction in accretion rate
is due to an accumulation of circulation near the accreting particle. Using a
combination of simulations and analytic treatment, we provide an approximate
formula for the accretion rate of gas onto a point particle as a function of
the vorticity of the surrounding gas.


title: Obscuration of Active Galactic Nuclei by Circumnuclear Starbursts

abstract:
  We examine the possibility of the active galactic nucleus (AGN) obscuration
by dusty gas clouds that spurt out from circumnuclear starburst regions. For
the purpose, the dynamical evolution of gas clouds is pursued, including the
effects of radiation forces by an AGN as well as a starburst. Here, we solve
the radiative transfer equations for clouds, taking into consideration the
growth of clouds by inelastic cloud-cloud collisions and the resultant change
in optical depth. As a result, it is shown that if the starburst is more
luminous than the AGN, gas clouds are distributed extensively above a galactic
disk with the assistance of radiation pressure from the starburst. The total
covering factor of gas clouds reaches a maximum of around 20%. After several
$10^{7}$yr, gas clouds with larger optical depth form by cloud-cloud collisions
and thereafter the clouds fall back due to weakened radiation pressure. The
larger clouds undergo runaway growth and are eventually distributed around the
equatorial plane on the inner sides of circumnuclear starburst regions. These
clouds have an optical depth of several tens. The result is qualitatively
consistent with the putative tendency that Seyfert 2 galaxies appear more
frequently associated with starbursts than Seyfert 1s. On the other hand, if
the AGN luminosity overwhelms that of the starburst, almost all clouds are
ejected from the galaxy due to the radiation pressure from the AGN, resulting
in the formation of a quasar-like object. The origin of obscuration of AGNs is
discussed with relevant observations.


title: Novel Geometrical Models of Relativistic Stars. I. The General Scheme

abstract:
  In a series of articles we describe a novel class of geometrical models of
relativistic stars. Our approach to the static spherically symmetric solutions
of Einstein equations is based on a careful physical analysis of radial gauge
conditions. It brings us to a two parameter family of relativistic stars
without stiff functional dependence between the stelar radius and stelar mass.
It turns out that within this family there do exist relativistic stars with
arbitrary large mass, which are to have arbitrary small radius and arbitrary
small luminosity. In addition, point particle idealization, as a limiting case
of bodies with finite dimension, becomes possible in GR, much like in Newton
gravity.


title:
Modelling the optical properties of composite and porous interstellar
  grains

abstract:
  There are indications that interstellar and interplanetary dust grains have
an inhomogeneous and fluffy structure. We investigate different methods to
describe light scattering by such composite particles. Both a model of layered
particles and discrete dipole calculations for particles with Rayleigh and
non-Rayleigh inclusions are used. The calculations demonstrate that porosity is
a key parameter for determining light scattering. We find that the optical
properties of the layered particles depend on the number and position of layers
if the number of layers is small ($\la 15$). For a larger number of layers the
scattering characteristics become independent of the layer sequence. The
optical properties of particles with inclusions depend on the size of
inclusions provided the porosity is large. The scattering characteristics of
very porous particles with inclusions of different sizes are found to be close
to those of multi-layered spheres. We compare the results of these calculations
with the predictions of the effective medium theories (EMT) which are often
used in astronomy as a tool to calculate the optical properties of composite
particles. The results of our analysis show that the internal structure of
grains (layers versus inclusions) only slightly affects the optics of particles
provided the porosity does not exceed 50%. It is also demonstrated that in this
case the optical properties of composite grains calculated with EMT agree with
the results of the exact method for layered particles. For larger porosity, the
standard EMT rules (i.e., Garnett and Bruggeman rules) give reliable results
for particles with Rayleigh inclusions only.


title:
Novel Geometrical Models of Relativistic Stars. II. Incompressible Stars
  and Heavy Black Dwarfs

abstract:
  In a series of articles we describe a novel class of geometrical models of
relativistic stars. Our approach to the static spherically symmetric solutions
of Einstein equations is based on a careful physical analysis of radial gauge
conditions.
  It turns out that there exist heavy black dwarfs: relativistic stars with
arbitrary large mass, which are to have arbitrary small radius and arbitrary
small luminosity. In the present article we mathematically prove this new
phenomena, using a detailed consideration of incompressible GR stars. We study
the whole two parameter family of solutions of extended TOV equations for
incompressible stars. This example is used to illustrate most of the basic
features of the new geometrical models of relativistic stars. Comparison with
newest observational data is discussed


title: On the variability of the iron line in Mrk 841

abstract:
  Petrucci et al. (2002; hereafter P02) have reported extraordinary behaviour
of the iron K alpha line in the type 1 AGN Mrk 841. At the XMM-Newton/EPIC
resolution, a narrow line was observed in a short observation, which then
apparently disappeared around 0.5 days later when another observation was
performed. The limits are such that the line cannot both be narrow, and
variable at this level, as the light-travel time places the material at a
radius where broadening by the black hole's gravitational field is inevitable.
Adding an additional observation taken before the P02 data, we present a
different interpretation of the apparent variability. The data support the
hypothesis that the line in fact varies in width, not only in flux. Rather than
showing no line, and despite the strong Compton reflection component, the final
observation exhibits broad emission at ~ 6.2-6.4 keV, with a width of ~0.8 keV,
typical of a relativistic accretion disc. We suggest that the apparently narrow
line in the early observations arises from local illumination by a flare
inducing an hotspot in the inner disc, which then becomes progressively
broadened as the disc rotates.


title: Muon and Gamma Bundles tracing Up-going Tau Neutrino Astronomy

abstract:
  Up-going and Horizontal Tau Air-Showers, UpTaus and HorTaus, may trace Ultra
High Energy Neutrino Tau Earth Skimming at the edge of the horizons. Their
secondaries muon, electron pairs, and gamma bundles flashes might trace their
nature over UHECR secondaries in horizontal showers. Indeed the atmosphere act
as a perfect amplifier as well as a filter for showers: down-ward and
horizontal muon bundles may still be originated by far Ultra High Energy Cosmic
Rays skimming the terrestrial atmosphere but their rich gamma component will be
exponentially suppressed. At large zenith angles after crossing a large slant
depth X > 3 10^3 g cm^-2 the number of muons and secondary gamma (produced by
the electron pair from muon decay in flight) is comparable. On the other hand,
up-ward muon bundles from UpTaus and HorTaus may arise within a young shower
with a larger gamma-muon ratio 10^2, leaving a characteristic imprint. We
estimate the UpTaus and HorTaus rate from the Earth and we evaluate the
consequent event rate of muons, electrons pairs andgamma bundles. We show that
such events even for minimal GZK neutrino fluxes could be detected by
scintillator arrays placed on mountains at 1-5km and pointing to the horizon.
The required arrayareas are within tens-hundreds of square meters. The ideal
structure is an array of crown-like twin detectors facing the horizons. We
argue that such detectors will be able to detect both muonic bundles at a
minimal average flux of 10^-11 cm-2 s^-1 sr^-1 and electromagnetic particles
gamma and electron pairs 3 10^-9 cm^-2 s^-1 sr^-1, a few times each year for
GZK neutrino fluxes.


title: Beyond the galaxy luminosity function

abstract:
  With the advent of large scale surveys (i.e., Legacy Surveys) it is now
possible to start looking beyond the galaxy luminosity function (LF) to more
detailed statistical representations of the galaxy population, i.e.,
multivariate distributions. In this review I first summarise the current
state-of-play of the B-band global and cluster LFs and then briefly present two
promising bivariate distributions: the luminosity-surface brightness plane
(LSP); and the colour-luminosity plane (CLP). In both planes galaxy bulges and
galaxy disks form marginally overlapping but distinct distributions, indicating
two key formation/evolutionary processes (presumably merger and accretion).
Forward progress in this subject now requires the routine application of
reliable bulge-disk decomposition codes to allow independent investigation of
these two key components.


title: Magnetic fields in Clusters of Galaxies

abstract:
  An important area of study of cosmic magnetic fields is on the largest
scales, those of clusters of galaxies. In the last decade it has become clear
that the intra-cluster medium (ICM) in clusters of galaxies is magnetized and
that magnetic fields play a critical role in the cluster formation and
evolution. The observational evidence for the existence of cluster magnetic
fields is obtained by the diffuse cluster-wide synchrotron radio emission and
from rotation measure (RM) studies of extragalactic radio sources located
within or behind the clusters. A significant breakthrough in the knowledge of
the cluster magnetic fields will be reached through the SKA, owing to its
capabilities, in particular the deep sensitivity and the polarization purity.


title: Variability and rotation of ultra cool dwarfs

abstract:
  Over the past few years monitoring programs have shown ultra cool dwarfs
(UCDs) to be photometrically variable. Of the 60 sources monitored in the field
and some 120 monitored in clusters, about 40% show variability in both cases.
For mid to late M dwarfs in young (<100 Myr) clusters, this variability is
generally periodic with amplitudes of up to a few tenths of a magnitude and
periods of between a few hours and several days. For older field dwarfs
(covering late M, L and T types) this variability is often nonperiodic with
smaller amplitudes (up to 0.1 mag in I) and timescales of order hours. The
former may be attributed to the rotational modulation of magnetically-induced
photospheric spots, as seen in higher mass T Tauri stars. The nonperiodic
variability, on the other hand, may be caused by a rapid evolution of surface
features (which 'mask' the otherwise observable rotational modulation). This
could be related to the formation and dissipation of inhomogeneities in dust
clouds in the photospheres of UCDs.