title: Low Temperature Opacities

abstract:
  Previous computations of low temperature Rosseland and Planck mean opacities
from Alexander & Ferguson (1994) are updated and expanded. The new computations
include a more complete equation of state with more grain species and updated
optical constants. Grains are now explicitly included in thermal equilibrium in
the equation of state calculation, which allows for a much wider range of grain
compositions to be accurately included than was previously the case. The
inclusion of high temperature condensates such as Al$_2$O$_3$ and CaTiO$_3$
significantly affects the total opacity over a narrow range of temperatures
before the appearance of the first silicate grains.
  The new opacity tables are tabulated for temperatures ranging from 30000 K to
500 K with gas densities from 10$^{-4}$ g cm$^{-3}$ to 10$^{-19}$ g cm$^{-3}$.
Comparisons with previous Rosseland mean opacity calculations are discussed. At
high temperatures, the agreement with OPAL and Opacity Project is quite good.
Comparisons at lower temperatures are more divergent as a result of differences
in molecular and grain physics included in different calculations. The
computation of Planck mean opacities performed with the opacity sampling method
are shown to require a very large number of opacity sampling wavelength points;
previously published results obtained with fewer wavelength points are shown to
be significantly in error. Methods for requesting or obtaining the new tables
are provided.


title: Progenitors of Core-Collapse Supernovae

abstract:
  The progenitors of core-collapse supernovae are stars with an initial mass
greater than about 8M(sun). Understanding the evolution of these stars is
necessary to comprehend the evolution and differences between supernovae.
  We have constructed new and unique opacity tables to increase model accuracy
during the latest stages of stellar evolution. We have investigated how initial
mass, initial composition and mass loss affects the progenitors and their
populations. There are many prescriptions for mass loss. Different research
groups use their preferred rates. We have compared 12 different prescriptions
and determined which provides the best fit to observations. We use our
preferred mass-loss scheme to make suggestions as to the source of the
differences between supernova types from our progenitor models.
  Binary evolution is considered in order to search for low luminosity SN
progenitors and progenitor types not possible from single stars. Removal of the
hydrogen envelope is more common and we find quite different hydrogen deficient
SN progenitors. We discuss the implications of our binary models for
ultra-luminous X-ray sources and gamma-ray bursts. We present an estimation of
the mass distribution for black holes at various metallcities showing that
massive black holes are not formed until very low metallicities. Finally we
combine the single star and binary results to determine their relative
populations and compare to observations. However it is not possible to draw
many firm conclusions because of the uncertainty in observations to date.


title: An extensive library of 2500-10500 Ang synthetic spectra

abstract:
  We present a complete library of synthetic spectra based on Kurucz's codes
that covers the 2500-10500 Ang wavelength range at resolving powers 20,000,
11,500 (GAIA), 8500 (RAVE), 2000 (SLOAN) and uniform dispersions of 1 and 10
Ang/pix. The library maps the whole HR diagram, exploring 51,288 combinations
of atmospheric parameters spanning the ranges: 3500 <= Teff <= 47500 K, 0.0 <=
log g <= 5.0, -2.5 <= [M/H] <= 0.5, [alpha/Fe] = 0.0,+0.4, xi =1,2,4 km/sec, 0
<= Vrot <= 500 km/sec. The spectra are available both as absolute fluxes as
well as continuum normalized. Performance tests and foreseen spectroscopic
applications of the library are discussed, including automatic classification
of data from surveys like RAVE, SLOAN, GAIA. The entire library of synthetic
spectra is accessible via http://archives.pd.astro.it/2500-10500/ or (for the 1
AA/pix version only)
http://gaia.esa.int/spectralib/spectralib1A/SpectraLib1a.cfm


title: Coronal Electron Scattering of Hot Spot Emission Around Black Holes

abstract:
  Using a Monte Carlo ray-tracing code in full general relativity, we calculate
the transport of photons from a geodesic hot spot emitter through a corona of
hot electrons surrounding a black hole. Each photon is followed until it is
either captured by the black hole or is detected by a distant observer. The
source is assumed to be a low-energy thermal emitter (T_em ~ 1 keV), isotropic
in the rest frame of a massive geodesic test particle. The coronal scattering
has two major observable effects: the Comptonization of the photon spectrum due
to the high energy electrons, and the convolution of the time-dependent light
curve as each photon is effectively scattered into a different time bin. Both
of these effects are clearly present in the Rossi X-Ray Timing Explorer (RXTE)
observations of high frequency quasi-periodic oscillations (QPOs) seen in black
hole binaries. These QPOs tend to occur when the system is in the Steep Power
Law spectral state and also show no evidence for significant power at higher
harmonic frequencies, consistent with the smoothing out of the light curve by
multiple random time delays. We present simulated photon spectra and light
curves and compare with RXTE data, allowing us to infer the properties of the
corona as well as the hot spot emitter.


title: Earth-mass dark halos are torn into dark mini-streams by stars

abstract:
  The promising neutralino dark matter particles generically condense into
numerous earth-mass dark halos with smaller substructures suppressed by free
streaming\cite{berezinsky}. The recent {\it Letter to Nature}\cite{moore}
claims that these 0.01pc-sized dense halos emerged at redshifts 60--26 are
rarely destructed inside galaxies, hence the nearest halos at about 0.1pc from
Earth are bright in annihilation-powered gamma-rays, but are inaccessible to
direct detections. However, most mini-halos reaching solar neighbourhood should
experience strong impulses by individual stars in the Galactic disk and bulge,
and have been torn into pc-long tidal streams over a Hubble time with only
modest overdensity, reducing indirect annihilation signals. Sweeping across the
solar system per century, mini-streams leave directional and temporal
signatures for direct searches of neutralinos.


title: Combined and Comparative Analysis of Power Spectra

abstract:
  In solar physics, especially in exploratory stages of research, it is often
necessary to compare the power spectra of two or more time series. One may, for
instance, wish to estimate what the power spectrum of the combined data sets
might have been, or one may wish to estimate the significance of a particular
peak that shows up in two or more power spectra. One may also on occasion need
to search for a complex of peaks in a single power spectrum, such as a
fundamental and one or more harmonics, or a fundamental plus sidebands, etc.
Visual inspection can be revealing, but it can also be misleading. This leads
one to look for one or more ways of forming statistics, which readily lend
themselves to significance estimation, from two or more power spectra. We
derive formulas for statistics formed from the sum, the minimum, and the
product of two or more power spectra. A distinguishing feature of our formulae
is that, if each power spectrum has an exponential distribution, each statistic
also has an exponential distribution.


title: Deposing the Cool Corona of KPD 0005+5106

abstract:
  The ROSAT PSPC pulse height spectrum of the peculiar He-rich hot white dwarf
KPD 0005+5106 provided a great surprise when first analysed by Fleming, Werner
& Barstow (1993). It defied the best non-LTE modelling attempts in terms of
photospheric emission from He-dominated atmospheres including C, N and O and
was instead interpreted as the first evidence for a coronal plasma around a
white dwarf. We show here that a recent high resolution Chandra LETGS spectrum
has more structure than expected from a thermal bremsstrahlung continuum and
lacks the narrow lines of H-like and He-like C expected from a coronal plasma.
Moreover, a coronal model requires a total luminosity more than two orders of
magnitude larger than that of the star itself. Instead, the observed 20-80 AA
flux is consistent with photospheric models containing trace amounts of heavier
elements such as Fe. The soft X-ray flux is highly sensitive to the adopted
metal abundance and provides a metal abundance diagnostic. The weak X-ray
emission at 1 keV announced by O'Dwyer et al (2003) instead cannot arise from
the photosphere and requires alternative explanations. We echo earlier
speculation that such emission arises in a shocked wind. Despite the presence
of UV-optical O VIII lines from transitions between levels n=7-10, no X-ray O
VIII Ly alpha flux is detected. We show that O VIII Lyman photons can be
trapped by resonant scattering within the emitting plasma and destroyed by
photoelectric absorption.


title: Pure and loaded fireballs in SGR giant flares

abstract:
  On December 27, 2004, a giant flare from SGR 1806$-$20 was detected on earth.
Its thermal spectrum and temperature suggest that the flare resulted from an
energy release of about $10^{47}$ erg/sec close to the surface of a neutron
star in the form of radiation and/or pairs. This plasma expanded under its own
pressure producing a fireball and the observed gamma-rays escaped once the
fireball became optically thin. The giant flare was followed by a bright radio
afterglow, with an observable extended size, implying an energetic relativistic
outflow. We revisit here the evolution of relativistic fireballs and we
calculate the Lorentz factor and energy remaining in relativistic outflow once
the radiation escapes. We show that pairs that arise naturally in a pure
pairs-radiation fireball do not carry enough energy to account for the observed
afterglow. We consider various alternatives and we show that if the
relativistic outflow that causes the afterglow is related directly to the
prompt flare, then the initial fireball must be loaded by baryons or Poynting
flux. While we focus on parameters applicable to the giant flare and the radio
afterglow of SGR 1806$-$20 the calculations presented here might be also
applicable to GRBs.


title: Imaging of Radio Supernovae

abstract:
  As the shock and expanding shell of a supernova plow out through the
circumstellar material at thousands of km/s, radio emission is generated. VLBI
observations of this radio emission are presently the only means to directly
image the expanding shell of any supernova much farther away than SN 1987A. The
last decade has seen great progress in VLBI imaging of radio supernovae. In
particular, SN 1993J in the galaxy M81 provided a rare opportunity to closely
study an expanding supernova, and has been intensively observed. I summarize
some of the results on SN 1993J and other radio supernovae, and compare the
different observed radio supernovae. I briefly discuss the future prospects of
radio supernovae imaging.


title:
Cosmological Constraints on the Very Low Frequency Gravitational-Wave
  Background

abstract:
  While there are no strong observational constraints on the gravitational wave
background across six or more orders of magnitude between 10^{-16} Hz and
10^{-10} Hz and it is difficult to get a constraint below 10^{-12}Hz using
objects in our Galaxy, we suggest that the anisotropy pattern of time variation
of the redshift related to a sample of high redshift objects can be used to
constrain the gravitational wave background around 10^{-12} Hz. Useful
observations for the monitoring of an anisotropy signal in a global redshift
change include spectroscopic observations of the Ly-alpha forest in absorption
towards a sample of quasars, redshifted 21 cm line observations either in
absorption or emission towards a sample of neutral HI regions before or during
reionization, and high frequency (0.1 Hz to 1
  Hz) gravitational wave analysis of a sample of neutron star--neutron star
binaries detected with gravitational wave instruments such as the Decihertz
Interferometer Gravitational Wave Observatory (DECIGO). The low frequency
background can also be constrained by arcsecond-scale anisotropy observations
of the CMB. For reasonable observations in the future involving extragalactic
sources, we find best limits at the level of \Omega_{GW} < 10^{-5} at a
frequency around 10^{-12} Hz while the eventual ultimate limit one cannot beat
is \Omega_{GW} < 10^{-11}.


title:
The Nature of Nearby Counterparts to Intermediate Redshift Luminous
  Compact Blue Galaxies II. CO Observations

abstract:
  We present the results of a single-dish beam-matched survey of the three
lowest rotational transitions of CO in a sample of 20 local (D < 70 Mpc)
Luminous Compact Blue Galaxies (LCBGs). These ~L*, blue, high surface
brightness, starbursting galaxies were selected with the same criteria used to
define LCBGs at higher redshifts. Our detection rate was 70%, with those
galaxies having Lblue<7e9 Lsun no detected. We find the H2 masses of local
LCBGs range from 6.6e6 to 2.7e9 Msun, assuming a Galactic CO-to-H2 conversion
factor. Combining these results with our earlier HI survey of the same sample,
we find that the ratio of molecular to atomic gas mass is low, typically 5-10%.
Using a Large Velocity Gradient model, we find that the average gas conditions
of the entire ISM in local LCBGs are similar to those found in the centers of
star forming regions in our Galaxy, and nuclear regions of other galaxies. Star
formation rates, determined from IRAS fluxes, are a few solar masses per year,
much higher per unit dynamical mass than normal spirals. If this rate remains
constant, the molecular hydrogen depletion time scales are short, 10-200 Myr.


title: Correcting systematic effects in a large set of photometric lightcurves

abstract:
  We suggest a new algorithm to remove systematic effects in a large set of
lightcurves obtained by a photometric survey. The algorithm can remove
systematic effects, like the ones associated with atmospheric extinction,
detector efficiency, or PSF changes over the detector. The algorithm works
without any prior knowledge of the effects, as long as they linearly appear in
many stars of the sample. The approach, which was originally developed to
remove atmospheric extinction effects, is based on a lower rank approximation
of matrices, an approach which was already suggested and used in chemometrics,
for example. The proposed algorithm is specially useful in cases where the
uncertainties of the measurements are unequal. For equal uncertainties the
algorithm reduces to the Principal Components Analysis (PCA) algorithm. We
present a simulation to demonstrate the effectiveness of the proposed algorithm
and point out its potential, in search for transit candidates in particular.


title: Energetics of Coronal Mass Ejections

abstract:
  We examine the energetics of the best examples of flux-rope CMEs observed by
LASCO in 1996-2001. We find that 69% of the CMEs in our sample experience a
driving power in the LASCO field of view. For these CMEs which are driven, we
examine if they might be deriving most of their driving energy by coupling to
the solar wind. We do not find conclusive evidence to support this hypothesis.
We adopt two different methods to estimate the energy that can possibly be
released by the internal magnetic fields of the CMEs. We find that the internal
magnetic fields are a viable source of driving power for these CMEs.


title: A Distinct Structure Inside the Galactic Bar

abstract:
  We present the result of a near-infrared (J H Ks) survey along the Galactic
plane, -10.5deg < l < +10.5deg and b=+1.0deg, with the IRSF 1.4m telescope and
the SIRIUS camera. Ks vs. H-Ks color-magnitude diagrams reveal a well-defined
population of red clump (RC) stars whose apparent magnitude peak changes
continuously along the Galactic plane, from Ks=13.4 at l=-10deg to Ks=12.2 at
l=+10deg after dereddening. This variation can be explained by the bar-like
structure found in previous studies, but we find an additional inner structure
at |l| < 4deg, where the longitude - apparent magnitude relation is distinct
from the outer bar, and the apparent magnitude peak changes by only 0.1 mag
over the central 8deg. The exact nature of this inner structure is as yet
uncertain.


title:
The Nature Of Radio Continuum Emission At Very Low Metallicity: Very
  Large Array Observations of I Zw 18

abstract:
  We present the first resolved study of the radio continuum properties of I Zw
18, the dwarf galaxy with the lowest known nebular metal abundance in the local
universe. New Very Large Array radio continuum images at 20 and 3.6 cm are
compared to various Hubble Space Telescope images, and we find a striking
morphological similarity between high-resolution H alpha and short wavelength
radio continuum emission, especially in the H alpha shell in the northwest
region. We separate thermal and nonthermal components of the emission, and find
a large synchrotron halo surrounding the galaxy. Comparison between H alpha and
X-band fluxes suggests that the emission at 3.6 cm is dominated by thermal
processes; an additional synchrotron component dominates the flux at 20 cm and
produces a modest fraction of the detected flux at 3.6 cm. The fluxes of three
of the four major emission peaks show a mix of thermal and nonthermal
processes, while one shows a nearly flat spectral index. The strong synchrotron
component argues for active star formation throughout the disk for at least the
last ~ 30 Myr. These sensitive observations provide a new, detailed view of the
nature of radio continuum emission in the very low metallicity interstellar
medium. Comparing with the literature, the role of metallicity in the evolution
of radio continuum emission seems to be secondary to other factors such as the
recent star formation history and the presence or absence of outflows from star
formation regions.


title: Evolution of V838 Monocerotis during and after the 2002 eruption

abstract:
  By fitting the available photometric data on V838 Mon with standard
supergiant spectra we have derived principal stellar parameters, i.e. effective
temperature, radius and luminosity, and followed the evolution of the object
since its discovery in early January 2002. Our analysis shows that the 2002
outburst of V838 Mon consisted of two major phases: pre-eruption which was
observed in January 2002 and a major outburst, called eruption, which started
in the beginning of February 2002. During pre-eruption the object seemed to be
relaxing after an initial event which had presumably taken place in last days
of December 2001. The eruption phase, which lasted till mid-April 2002,
resulted from a very strong energy burst, which presumably took place in last
days of January at the base of the stellar envelope inflated in pre-eruption.
The burst produced an energy wave, which was observed as a strong luminosity
flash in the beginning of February, followed by a strong mass outflow in form
of two shells, which was observed as an expanding photosphere in later epochs.
In mid-April, when the outflow became optically transparent and most of its
energy radiated away, the object entered the decline phase during which V838
Mon was evolving along the Hayashi track. This we interpret as an evidence that
the main energy source during decline was due to gravitational contraction of
the object envelope inflated in eruption. Late in 2002 a dust formation started
in the expanding shells which gave rise to a strong infrared excess observed in
2003.


title: Triggered Star Formation in the Orion Bright-Rimmed Clouds

abstract:
  We have developed an empirical and effective set of criteria, based on the
2MASS colors, to select candidate classical T Tauri stars (CTTS). This provides
a useful tool to study the young stellar population in star-forming regions.
Here we present our analysis of the bright-rimmed clouds (BRCs) B 35, B 30, IC
2118, LDN 1616, LDN 1634, and Orion East to show how massive stars interact
with molecular clouds to trigger star formation. Our results support the
radiation-driven implosion model in which the ionization fronts from OB stars
compress a nearby cloud until the local density exceeds the critical value,
thereby inducing the cloud to collapse to form stars. We find that only BRCs
associated with strong IRAS 100 micron emission (tracer of high density) and
H-alpha emission (tracer of ionization fronts) show signs of ongoing star
formation. Relevant timescales, including the ages of O stars, expanding HII
regions, and the ages of CTTS, are consistent with sequential star formation.
We also find that CTTS are only seen between the OB stars and the BRCs, with
those closer to the BRCs being progressively younger. There are no CTTS leading
the ionization fronts, i.e., within the molecular clouds. All these provide
strong evidence of triggered star formation and show the major roles massive
stars play in sustaining the star-forming activities in the region.


title:
Morphology of low-redshift compact galaxy clusters I. Shapes and radial
  profiles

abstract:
  The morphology of clusters of galaxies may be described with a set of
parameters which contain information about the formation and evolutionary
history of these systems. In this paper we present a preliminary study of the
morphological parameters of a sample of 28 compact Abell clusters extracted
from DPOSS data. The morphology of galaxy clusters is parameterized by their
apparent ellipticity, position angle of the major axis, centre coordinates,
core radius and beta-model power law index. Our procedure provides estimates of
these parameters by simultaneously fitting them all, overcoming some of the
difficulties induced by sparse data and low number statistics typical of this
kind of analysis. The cluster parameters were fitted in a 3 x 3 h^-2 sqMpc
region, measuring the background in a 2 <R< 2.5 h^-1Mpc annulus. We also
explore the correlations between shape and profile parameters and other cluster
properties. One third of this compact cluster sample has core radii smaller
than 50 h^-1 kpc, i.e. near the limit that our data allow us to resolve,
possibly consistent with cusped models. The remaining clusters span a broad
range of core radii up to 750 h^-1 kpc. More than 80 per cent of this sample
has ellipticity higher than 0.2. The alignment between the cluster and the
major axis of the dominant galaxy is confirmed, while no correlation is
observed with other bright cluster members. No significant correlation is found
between cluster richness and ellipticity. Instead, cluster richness is found to
correlate, albeit with large scatter, with the cluster core radius.[abridged]


title: Flare X-ray observations of AB Dor: evidence for Stellar Coronal Opacity

abstract:
  X-ray spectra of the late-type star AB Dor, obtained with the XMM-Newton
satellite are analysed. AB Dor was particularly active during the observations.
An emission measure reconstruction technique is employed to analyse flare and
quiescent spectra, with emphasis on the Fe XVII 15-17 A wavelength region. The
Fe XVII 16.78 A/15.01 A line ratio increases significantly in the hotter flare
plasma. This change in the ratio is opposite to the theoretical predictions and
is attributed to the scattering of 15.01 A line photons from the line-of-sight.
The escape probability technique indicates an optical depth of about 0.4 for
the 15.01 A line. During the flare, the electron density is 4.4*10^10 cm^-3 and
the fractional Fe abundance is 0.5 +/- 0.1 of the solar photospheric value.
Using these parameters a path length of about 8,000 km is derived. There is no
evidence for opacity in the quiescent X-ray spectrum of the star.


title:
Bipolar jets growth and decline in Hen 3-1341: a direct link to fast
  wind and outburst evolution

abstract:
  The appearance and disappearance of collimated bipolar jets in the symbiotic
star Hen 3-1341 is reported and investigated. From modeling of the emission
line spectrum it turns out that the accreting white dwarf in quiescence has
T_WD ~ 1.2 10(5) K and R_WD ~ 0.14 Rsun, for a luminosity of 3.8 10(3) Lsun,
and it is stably burning hydrogen on the surface at a rate of 5 10(-8) Msun/yr,
feeding ionizing photons to a radiation bounded circumstellar nebula extending
for ~ 17 AU. The WD underwent a multi-maxima outburst lasting from 1998 to 2004
during which its H-burning envelope reacted to a probable small increase in the
mass accretion by expanding and cooling to T_eff ~ 1 10(4) K and R ~ 20 Rsun,
mimicking an A-type giant that radiated a total of 6 10(44) erg during the
outburst, at an average rate of 1 10(3) Lsun. Bipolar jets developed at the
time of outburst maximum and their strength declined in parallel with the
demise of a fast wind from the WD, finally disappearing when the wind stopped
halfway to quiescence, marking a 1:1 correspondence between jets presence and
feeding action of the fast wind. The total mass in the jets was M_jet ~ 2.5
10(-7) Msun for a kinetic energy of E_jet ~ 1.7 10(42)/(sin i) erg,
corresponding to 0.3/(sin i) percent of the energy radiated during the whole
outburst.


title:
Search for Sources of Primary Cosmic Rays at Energies Above 0.1 Pev at
  Tien Shan

abstract:
  Analysis of the experimental data of joint Russian - Hungarian research was
carried out at Tien Shan station on the search of sources of primary cosmic
rays (PCR) at energies 0.1-1.0 PeV. Maps of extensive air shower arrival
directions were presented where the standard deviation of mean event numbers in
equatorial co-ordinates exceeded a definite value. The excess of EAS number was
observed from an Galaxy object - the SN remnant and some other directions. The
young pulsar PSR 0656+14 located near the centre of this object.


title:
The faint supernova remnant G 116.5+1.1 and the detection of a new
  candidate remnant

abstract:
  The extended supernova remnant G 116.5+1.1 was observed in the optical
emission lines of Halpha+[N II], [S II] and [O III]; deep long-slit spectra
were also obtained. The morphology of the remnant's observed emission is mainly
diffuse and patchy in contrast to the known filamentary emission seen along the
western limb. The bulk of the detected emission in the region appears unrelated
to the remnant but there is one area of emission in the south-east which is
characterized by a [S II]/Halpha ratio of ~0.5, implying a possible relation to
G 116.5+1.1. If this is actually the case, it would imply a more extended
remnant than previously realized. Emission in the [O III] 5007 A line image is
not detected, excluding moderate or fast velocity shocks running into ionized
interstellar clouds. Our current estimate of the distance to G 116.5+1.1 of ~3
kpc is in agreement with earlier estimates and implies a very extended remnant
(69 pc x 45 pc). Observations further to the north-east of G 116.5+1.1 revealed
a network of filamentary structures prominent in Halpha+[N II] and [S II] but
failed to detect [O III] line emission. Long-slit spectra in a number of
positions provide strong evidence that this newly detected emission arises from
shock heated gas. Typical Halpha fluxes lie in the range of 9 to 17 x10^{-17}
erg/s/cm^2/ arcsec^2, while low electron densities are implied by the
intensities of the sulfur lines. Weak emission from the medium ionization line
at 5007 A is detected in only one spectrum. Cool dust emission at 60 and 100
microns may be correlated with the optical emission in a limited number of
positions. Surpisingly, radio emission is not detected in published surveys
suggesting that the new candidate remnant may belong to the class of "radio
quiet" supernova remnants.


title:
Attenuation law of normal disc galaxies with clumpy distributions of
  stars and dust

abstract:
  We investigate the attenuation law seen through an interstellar medium (ISM)
with clumpy spatial distributions of stars and dust. The clumpiness of the dust
distribution is introduced by a multi-phase ISM model. We solve a set of
radiative transfer equations with multiple anisotropic scatterings through the
clumpy ISM in a 1-D plane-parallel geometry by using the mega-grain
approximation, in which dusty clumps are regarded as very large particles (i.e.
mega-grains). The clumpiness of the stellar distribution is introduced by the
youngest stars embedded in the clumps. We assume a smooth spatial distribution
for older stars. The youngest stars are surrounded by denser dusty gas and
suffer stronger attenuation than diffuse older stars (i.e. age-selective
attenuation). The apparent attenuation law is a composite of the attenuation
laws for the clumpy younger stars and for the diffuse older stars with a
luminosity weight. In general, the stellar population dominating the luminosity
changes from older stars to younger stars as the wavelength decreases. This
makes the attenuation law steep; the composite attenuation rapidly increases
from small attenuation for older stars at a long wavelength to large
attenuation for younger stars at a short wavelength. The resultant attenuation
law of normal disc galaxies is expected to be much steeper than that of
starburst galaxies observed by Calzetti et al. Finally, the Calzetti's
attenuation law is regarded as a special case with a large density in our
framework.


title: The Interiors of Giant Planets: Models and Outstanding Questions

abstract:
  We know that giant planets played a crucial role in the making of our Solar
System. The discovery of giant planets orbiting other stars is a formidable
opportunity to learn more about these objects, what is their composition, how
various processes influence their structure and evolution, and most importantly
how they form. Jupiter, Saturn, Uranus and Neptune can be studied in detail,
mostly from close spacecraft flybys. We can infer that they are all enriched in
heavy elements compared to the Sun, with the relative global enrichments
increasing with distance to the Sun. We can also infer that they possess dense
cores of varied masses. The intercomparison of presently caracterised
extrasolar giant planets show that they are also mainly made of hydrogen and
helium, but that they either have significantly different amounts of heavy
elements, or have had different orbital evolutions, or both. Hence, many
questions remain and are to be answered for significant progresses on the
origins of planets.


title: Coupling Quintessence to Inflation in Supergravity

abstract:
  The evolution of the quintessence field during a phase of chaotic inflation
is studied. The inflaton and the quintesssence field are described in a
supergravity framework where the coupling between the inflaton and quintessence
is induced by non-renormalisable operators suppressed by the Planck mass. We
show that the resulting quintessence potential during inflation possesses a
time--dependent minimum playing the role of an attractor. The presence of this
attractor forces the quintessence field to be small during inflation. These
initial conditions are such that the quintessence field is on tracks now.


title:
The efficiency of electron acceleration in collisionless shocks and GRB
  energetics

abstract:
  Afterglow observations are commonly used to determine the parameters of GRB
explosions, the energy E, surrounding density n, post-shock magnetic field
equipartition fraction \epsilon_B and electron equipartition fraction
\epsilon_e, under the frequently made assumption that the efficiency of
electron "injection" into relativistic shock acceleration is high, i.e. that
the fraction f of electrons which undergo acceleration is f~1. We show that the
value of f can not be determined by current observations, since currently
testable model predictions for a parameter choice
{E'=E/f,n'=n/f,\epsilon'_B=f\epsilon_B,\epsilon'_e=f\epsilon_e} are independent
of the value of f for m_e/m_p< f< 1. Current observations imply that the
efficiency f is similar for highly relativistic and for sub relativistic
shocks, and plausibly suggest that f~1, quite unlike the situation in the Crab
Nebula. However, values m_e/m_p< f<< 1 can not be ruled out, implying a factor
m_e/m_p uncertainty in determination of model parameters. We show that early,
<10 hr, radio afterglow observations, which will be far more accessible in the
SWIFT era, may provide constraints on f. Such observations will therefore
provide a powerful diagnostic of GRB explosions and of the physics of particle
acceleration in collisionless shocks.


title: A detailed study of the rotating toroids in G31.41+0.31 and G24.78+0.08

abstract:
  We present the results of high angular resolution millimeter observations of
gas and dust toward G31.41+0.31 and G24.78+0.08, two high-mass star forming
regions where four rotating massive toroids have been previously detected by
Beltran et al. (2004). The CH3CN (12-11) emission of the toroids in G31.41+0.31
and core A1 in G24.78+0.08 has been modeled assuming that it arises from a
disk-like structure seen edge-on, with a radial velocity field. For G31.41+0.31
the model properly fits the data for a velocity v_rot~1.7 km/s at the outer
radius R_out~13400 AU and an inner radius R_inn~1340 AU, while for core A1 in
G24.78+0.08 the best fit is obtained for v_rot~2.0 km/s at R_out~7700 AU and
R_inn~2300 AU. Unlike the rotating disks detected around less luminous stars,
these toroids are not undergoing Keplerian rotation. From the modeling itself,
however, it is not possible to distinguish between constant rotation or
constant angular velocity, since both velocity fields suitably fit the data.
The best fit models have been computed adopting a temperature gradient of the
type T proportional R^{-3/4}, with a temperature at the outer radius T_out~100
K for both cores. The M_dyn needed for equilibrium derived from the models is
much smaller than the mass of the cores, suggesting that such toroids are
unstable and undergoing gravitational collapse. The collapse is also supported
by the CH3^{13}CN or CH3CN line width measured in the cores, which increases
toward the center of the toroids. The estimates of v_inf and \dot M_acc are ~2
km/s and 3x10^{-2} M_sun/yr for G31.41+0.31, and ~1.2 km/s and ~9x10^{-3}
M_sun/yr for G24.78+0.08 A1. Such large accretion rates could weaken the effect
of stellar winds and radiation pressure and allow further accretion on the
star.


title:
HST/FOS Time-resolved spectral mapping of IP Pegasi at the end of an
  outburst

abstract:
  We report an eclipse mapping analysis of time-resolved ultraviolet
spectroscopy covering three eclipses of the dwarf nova IP Pegasi on the late
decline of the 1993 May outburst. The eclipse maps of the first run show
evidence of one spiral arm, suggesting that spiral structures may still be
present in the accretion disc 9 days after the onset of the outburst. In the
spatially resolved spectra the most prominent lines appear in emission at any
radius, being stronger in the inner disc regions. The spectrum of the gas
stream is clearly distinct from the disc spectrum in the intermediate and outer
disc regions, suggesting the occurrence of gas stream overflow. The full width
half maximum of C IV is approximately constant with radius, in contrast to the
expected $v\propto{R^{-1/2}}$ law for a gas in Keplerian orbits. This line
probably originates in a vertically extended region (chromosphere + disc wind).
The uneclipsed component contributes $\sim{4}$ % of the flux in C IV in the
first run, and becomes negligible in the remaining runs. We fit stellar
atmosphere models to the spatially resolved spectra. The radial run of the disc
color temperature for the three runs is flatter than the expected
$T\propto{R^{-3/4}}$ law for steady-state optically thick discs models, with
$T\simeq{20000}$ K in the inner regions and $T\simeq{9000}$ K in the outer disc
regions. The solid angles that result from the fits are smaller than expected
from the parameters of the system. The radial run of the solid angle suggests
that the disc is flared in outburst, and decreases in thickness toward the end
of the outburst.


title: Detection of 75+ pulsation frequencies in the Delta Scuti star FG Vir

abstract:
  Extensive photometric multisite campaigns of the Delta Scuti variable FG Vir
are presented. For the years 2003 and 2004, 926 hours of photometry at the
millimag precision level were obtained. The combinations with earlier campaigns
lead to excellent frequency resolution and high signal/noise. A multifrequency
analysis yields 79 frequencies. This represents a new record for this type of
star. The modes discovered earlier were confirmed. Pulsation occurs over a wide
frequency band from 5.7 to 44.3 c/d with amplitudes of 0.2 mmag or larger.
Within this wide band the frequencies are not distributed at random, but tend
to cluster in groups. A similar feature is seen in the power spectrum of the
residuals after 79 frequencies are prewhitened. This indicates that many
additional modes are excited. The interpretation is supported by a histogram of
the photometric amplitudes, which shows an increase of modes with small
amplitudes. The old question of the 'missing modes' may be answered now: the
large number of detected frequencies as well as the large number of additional
frequencies suggested by the power spectrum of the residuals con rms the
theoretical prediction of a large number of excited modes. FG Vir shows a
number of frequency combinations of the dominant mode at 12.7162 c/d (m = 0)
with other modes of relatively high photometric amplitudes. The amplitudes of
the frequency sums are higher than those of the differences. A second mode
(20.2878 c/d) also shows combinations. This mode of azimuthal order m = -1 is
coupled with two other modes of m = +1.


title: Discovery of NeVII in the Winds of Hot Evolved Stars

abstract:
  We show that a strong P-Cygni feature seen in the far-UV spectra of some very
hot (Teff >~ 85 kK) central stars of planetary nebulae (CSPN), which has been
previously identified as CIII lambda 977, actually originates from NeVII lambda
973. Using stellar atmospheres models, we reproduce this feature seen in the
spectra of two [WR]-PG 1159 type CSPN, Abell 78 and NGC 2371, and in one PG
1159 CSPN, K 1-16. In the latter case, our analysis suggests an enhanced neon
abundance. Strong neon features in CSPN spectra are important because an
overabundance of this element is indicative of processed material that has been
dredged up to the surface from the inter-shell region in the ``born-again''
scenario, an explanation of hydrogen-deficient CSPN. Our modeling indicates the
NeVII lambda 973 wind feature may be used to discern enhanced neon abundances
for stars showing an unsaturated P-Cygni profile, such as some PG 1159 stars.
We explore the potential of this strong feature as a wind diagnostic in stellar
atmospheres analyses for evolved objects. For the [WR]-PG 1159 objects, the
line is present as a P-Cygni line for Teff >~ 85 kK, and becomes strong for 100
<~ Teff <~ 155 kK when the neon abundance is solar, and can be significantly
strong beyond this range for higher neon abundances. When unsaturated, i.e.,
for very high Teff and/or very low mass-loss rates, it is sensitive to Mdot and
very sensitive to the neon abundance. The NeVII classification is consistent
with recent identification of this line seen in absorption in many PG 1159
spectra.


title:
A dichotomy in the orientation of dust and radio jets in nearby
  low-power radio galaxies

abstract:
  We examine the properties of central dust in nearby quiescent and active
early-type galaxies. The active galaxies are low-power radio galaxies with
Fanaroff & Riley Type I or I/II radio jets. We focus on the comparison of the
dust distributions in the active and quiescent galaxy samples and the relation
between the radio jet and dust orientations. Our main observational conclusions
are: (a) radio galaxies contain a higher fraction of regular dust 'ellipses'
compared to quiescent galaxies which contain more often irregular dust
distributions; (b) the morphology, size and orientation of dust ellipses and
lanes in quiescent early-types and active early-types with kpc-scale radio jets
is very similar; (c) dust ellipses are aligned with the major axis of the
galaxy, dust lanes do not show a preferred alignment except for large (>kpc)
dust lanes which are aligned with the minor axis of the galaxy. Dust
morphologies can be classified as regular 'ellipses' and filamentary 'lanes'.
We show that the dust ellipses are consistent with being nearly circular thin
disks viewed at random viewing angles. The lanes are likely warped dust
structures, which may be in the process of settling down to become regular
disks or are being perturbed by a non-gravitational force. We use the observed
dust-jet orientations to constrain the three-dimensional angle $\theta_{\rm
DJ}$ between jet and dust. For dust-lane galaxies, the jet is approximately
perpendicular to the dust structure, while for dust-ellipse galaxies there is a
much wider distribution of $\theta_{\rm DJ}$. We discuss two scenarios that
could explain the dust/jet/galaxy orientation dichotomy. (abridged)


title: Ultraviolet, X-ray, and Optical Radiation from the Geminga Pulsar

abstract:
  We observed the gamma-ray pulsar Geminga with the HST STIS/MAMA detectors to
measure the Geminga's UV spectrum and pulsations. The slope of the far-UV (FUV)
spectrum is close to that of a Rayleigh-Jeans spectrum, suggesting that the FUV
radiation is dominated by thermal emission from the neutron star (NS) surface.
The measured FUV flux, F_FUV=(3.7+/-0.2)x10^-15 ergs cm^-2 s^-1 in 1155-1702 A
band, corresponds to a brightness temperature T_RJ=(0.3-0.4)(d_200/R_13)^2 MK.
The soft thermal component of the Geminga's X-ray spectrum measured with the
XMM-Newton observatory corresponds to a temperature T_s=0.49+/-0.01 MK and
radius R_s = (12.9+/-1.0)d_200 km. Unlike other NSs detected in the UV-optical,
the FUV spectrum of Geminga lies below the extrapolation of the soft thermal
component, which might be associated with the Geminga's very low temperature.
Surprisingly, the thermal FUV radiation is strongly pulsed, showing a narrow
dip at a phase close to that of a broader minimum of the soft X-ray light
curve. The strong pulsations might be attributed to partial occultations of the
thermal UV radiation by regions of the magnetosphere filled with
electron/positron plasma. In contrast with the FUV spectrum, the near-IR (NIR)
through near-UV (NUV) spectrum of Geminga is clearly nonthermal. It can be
described by a power-law model, F_nu \propto nu^{-alpha} with a slope alpha =
0.43+/-0.15, close to alpha = 0.56+/-0.24 of the hard X-ray (E>2.5 keV)
magnetospheric component. The observed NIR-optical-NUV spectrum is marginally
consistent with the extrapolation of the X-ray magnetospheric spectrum. The NUV
pulsations, however, do not show a clear correlation with the hard X-ray
pulsations.


title:
CO Line Emission and Absorption from the HL Tau Disk: Where is all the
  dust?

abstract:
  We present high-resolution infrared spectra of HL Tau, a heavily embedded
young star. The spectra exhibit broad emission lines of hot CO gas as well as
narrow absorption lines of cold CO gas. The column density for this cooler
material (7.5+/-0.2 x 10^18 cm-2) indicates a large column of absorbing gas
along the line of sight. In dense interstellar clouds, this column density of
CO gas is associated with Av~52 magnitudes. However, the extinction toward this
source (Av~23) suggests that there is less dust along the line of sight than
inferred from the CO absorption data. We discuss three possibilities for the
apparent paucity of dust along the line of sight through the flared disk: 1)
the dust extinction has been underestimated due to differences in circumstellar
grain properties, such as grain agglomeration; 2) the effect of scattering has
been underestimated and the actual extinction is much higher; or (3) the line
of sight through the disk is probing a gas-rich, dust-depleted region, possibly
due to the stratification of gas and dust in a pre-planetary disk.


title:
Disk-Halo-Disk Circulation and the Evolution of the ISM - 3D HD and MHD
  Adaptive Mesh Refinement Simulations

abstract:
  State of the art models of the ISM use adaptive mesh refinement to capture
small scale structures, by refining on the fly those regions of the grid where
density and pressure gradients occur, keeping at the same time the existing
resolution in the other regions. With this technique it became possible to
study the ISM in star-forming galaxies in a global way by following matter
circulation between stars and the interstellar gas, and, in particular the
energy input by random and clustered supernova explosions, which determine the
dynamical and chemical evolution of the ISM, and hence of the galaxy as a
whole. In this paper we review the conditions for a self-consistent modelling
of the ISM and present the results from the latest developments in the 3D
HD/MHD global models of the ISM. Special emphasis is put on the effects of the
magnetic field with respect to the volume and mass fractions of the different
ISM ``phases'', the relative importance of ram, thermal and magnetic pressures,
and whether the field can prevent matter transport from the disk into the halo.
The simulations were performed on a grid with a square area of 1 kpc$^{2}$,
centered on the solar circle, extending $\pm 10$ kpc perpendicular to the
galactic disk with a resolution as high as 1.25 pc. The run time scale was 400
Myr, sufficiently long to avoid memory effects of the initial setup, and to
allow for a global dynamical equilibrium to be reached in case of a constant
energy input rate.


title: Reduction Algorithms for the Multiband Imaging Photometer for Spitzer

abstract:
  We describe the data reduction algorithms for the Multiband Imaging
Photometer for Spitzer (MIPS) instrument. These algorithms were based on
extensive preflight testing and modeling of the Si:As (24 micron) and Ge:Ga (70
and 160 micron) arrays in MIPS and have been refined based on initial flight
data. The behaviors we describe are typical of state-of-the-art infrared focal
planes operated in the low backgrounds of space. The Ge arrays are bulk
photoconductors and therefore show a variety of artifacts that must be removed
to calibrate the data. The Si array, while better behaved than the Ge arrays,
does show a handful of artifacts that also must be removed to calibrate the
data. The data reduction to remove these effects is divided into three parts.
The first part converts the non-destructively read data ramps into slopes while
removing artifacts with time constants of the order of the exposure time. The
second part calibrates the slope measurements while removing artifacts with
time constants longer than the exposure time. The third part uses the
redundancy inherit in the MIPS observing modes to improve the artifact removal
iteratively. For each of these steps, we illustrate the relevant laboratory
experiments or theoretical arguments along with the mathematical approaches
taken to calibrate the data. Finally, we describe how these preflight
algorithms have performed on actual flight data.


title:
Reduction Algorithms for the Multiband Imaging Photometer for Spitzer: 6
  Months of Flight Data

abstract:
  The first six months of flight data from the Multiband Imaging Photometer for
Spitzer (MIPS) were used to test MIPS reduction algorithms based on extensive
preflight laboratory data and modeling. The underlying approach for the
preflight algorithms has been found to be sound, but some modifications have
improved the performance. The main changes are scan mirror dependent flat
fields at 24 micron, hand processing to remove the time dependent stim flash
latents and fast/slow response variations at 70 micron, and the use of
asteroids and other sources instead of stars for flux calibration at 160 micron
due to a blue ``leak.'' The photometric accuracy of flux measurpements is
currently 5%, 10%, and 20% at 24, 70, and 160 micron, respectively. These
numbers are expected to improve as more flight data are analyzed and data
reduction algorithms refined.


title: Information content of the non-linear matter power spectrum

abstract:
  We use an ensemble of N-body simulations of the currently favoured
(concordance) cosmological model to measure the amount of information contained
in the non-linear matter power spectrum about the amplitude of the initial
power spectrum. Two surprising results emerge from this study: (i) that there
is very little independent information in the power spectrum in the translinear
regime (k ~ 0.2-0.8 Mpc/h at the present day) over and above the information at
linear scales and (ii) that the cumulative information begins to rise sharply
again with increasing wavenumber in the non-linear regime. In the fully
non-linear regime, the simulations are consistent with no loss of information
during translinear and non-linear evolution. If this is indeed the case then
the results suggest a picture in which translinear collapse is very rapid, and
is followed by a bounce prior to virialization, impelling a wholesale revision
of the HKLM-PD formalism.


title:
Gemini Near Infrared Spectrograph Observations of a Red Star Forming
  Galaxy at z=2.225: Evidence for Shock-Ionization due to a Galactic Wind

abstract:
  Recent studies have shown that K-luminous galaxies at 2<z<2.5 have high
Halpha line widths and high [NII]/Halpha ratios. If these lines arise from
photo-ionization by massive stars in HII regions these results imply that
massive, metal rich galaxies exist at high redshift. Here we investigate the
ionization mechanism in a galaxy with Ks=19.1 and z=2.225 in the Chandra Deep
Field South, using the new Gemini Near Infrared Spectrograph (GNIRS). GNIRS'
cross-dispersed mode gives simultaneous access to the entire 1-2.5 micron
wavelength range, allowing accurate measurements of line ratios of distant
galaxies. From the ratio of Halpha/Hbeta we infer that the line emitting gas is
heavily obscured, with E(B-V)=0.8. The reddening is higher than that inferred
previously from the UV-optical continuum emission, consistent with findings for
nearby star burst galaxies. We find that the galaxy has Seyfert-like line
ratios, [NII]/Halpha ~ 0.6 and [OIII]/Hbeta ~ 6, which can be caused by
photo-ionization by an active galactic nucleus (AGN) or shock ionization due to
a strong galactic wind. Although we cannot exclude the presence of an AGN, the
lack of AGN spectral features in the rest-frame ultraviolet, the consistency of
radio, X-ray, and rest-frame UV star formation indicators, the fact that the
[OIII]/Hbeta ratio remains high out to ~10 kpc from the nucleus, and the
observed gas kinematics all argue for the wind hypothesis. Similar
shock-induced ionization is seen in nearby star burst galaxies with strong
winds. The evidence for shock ionization implies that measurements of
metallicities and dynamical masses of star forming z>2 galaxies should be
regarded with caution, especially since the existence of strong galactic winds
in these objects is well established. [ABRIDGED]


title: Probing the Epoch of Early Baryonic Infall Through 21cm Fluctuations

abstract:
  After cosmological recombination, the primordial hydrogen gas decoupled from
the cosmic microwave background (CMB) and fell into the gravitational potential
wells of the dark matter. The neutral hydrogen imprinted acoustic oscillations
on the pattern of brightness fluctuations due to its redshifted 21cm absorption
of the CMB. Unlike CMB temperature fluctuations which probe the power spectrum
at cosmic recombination, we show that observations of the 21cm fluctuations at
z ~ 20-200 can measure four separate fluctuation modes (with a fifth mode
requiring very high precision), thus providing a unique probe of the geometry
and composition of the universe.


title: Universal GRB jets from jet-cocoon interaction in massive stars

abstract:
  We consider the time-dependent evolution of a relativistic jet following its
breakout through the surface of a massive compact star, as envisaged in the
collapsar model of gamma-ray bursts. At breakout, the jet is tightly collimated
by the pressure of its hot cocoon, which is created as the jet traverses the
star. After breakout, the cocoon pressure drops and the jet expands toward its
natural opening angle. We show that the evolving opening angle of the jet
produces a stratification of the total energy with the off-axis angle,
resulting in a universal morphology. The angular structure is largely
independent of the initial beam pattern and depends only on the luminosity of
the central engine. With the minimal assumption of a constant energy release we
reproduce the theta^{-2} profile required to explain observations of
afterglows.


title:
An energetic blast wave from the December 27 giant flare of the soft
  gamma-ray repeater 1806-20

abstract:
  Recent follow-up observations of the December 27 giant flare of SGR 1806-20
have detected a multiple-frequency radio afterglow from 240 MHz to 8.46 GHz,
extending in time from a week to about a month after the flare. The angular
size of the source was also measured for the first time. Here we show that this
radio afterglow gives the first piece of clear evidence that an energetic blast
wave sweeps up its surrounding medium and produces a synchrotron afterglow, the
same mechanism as established for gamma-ray burst afterglows. The optical
afterglow is expected to be intrinsically as bright as $m_R\simeq13$ at $t\la
0.1$ days after the flare, but very heavy extinction makes the detection
difficult because of the low galactic latitude of the source. Rapid infrared
follow-up observations to giant flares are therefore crucial for the
low-latitude SGRs, while for high-latitude SGRs (e.g. SGR 0526-66), rapid
follow-ups should result in identification of their possible optical
afterglows. Rapid multi-wavelength follow-ups will also provide more detailed
information of the early evolution of a fireball as well as its composition.


title:
A Possible Formation Scenario for the Ultra-Massive Cluster W3 in NGC
  7252

abstract:
  The intermediate age star cluster W3 (age ~ 300-500 Myr) in NGC 7252 is the
most luminous star cluster known to date with a dynamical mass estimate of 8
+/- 2 x 10^7 M_sun. With an effective radius of about 17.5 pc and a velocity
dispersion of 45 km/s this object may be viewed as one of the recently
discovered ultra-compact dwarf galaxies (UCDs). Its intermediate age, however,
precludes an origin as a stripped nucleated dwarf elliptical galaxy. The galaxy
NGC 7252 is a merger remnant from two gas-rich disc galaxies. Interactions
between two gas-rich galaxies lead to bursts of intense star formation. The age
of the interaction and the age of W3 are in good agreement, suggesting that was
W3 probably formed in the starburst. We propose a formation scenario for W3.
Observations of interacting galaxies reveal regions of strong star formation
forming dozens up to hundreds of star cluster in confined regions of up to
several hundred parsec in diameter. The total mass of new stars in these
regions can reach 10^7 or even 10^8 M_sun. By means of numerical simulations we
have shown that the star clusters in these regions merge on short time-scales
of a few Myr up to a few hundred Myr. We apply this scenario to W3 and predict
properties which could be observable and the future evolution of this object.
This work lends credence to the notion that at least some of the UCDs may be
evolved star cluster complexes formed during early hierarchical mergers.


title:
QSO 0957+561 and other large-separated double quasars: some new results
  and a future observational project

abstract:
  We collected from literature the information about large-separated pairs of
QSOs, which however once were suspected as gravitationally lensed system. We
discuss some new results on time delay determinations including optical-radio
correlations for QSO 0957+561. We considered some possible observational
effects of gravitational lensing by a cosmic string. A future international
project for observations of the gravitational lens system UM425 is briefly
discussed.


title: Phase Correlations and Topological Measures of Large-scale Structure

abstract:
  In these lecture notes I discussed the importance of phase correlations for
the morphology of large-scale structure and how phase analysis can probe
primordial non-Gaussianity and/or foreground contamination in CMB temperature
maps. I illustrate the ideas with application to the preliminary WMAP
first-year data. I also briefly introduce topological characteristics such as
the genus and Minkowski functionals, and how they provide a real-space
diagnostic of phase correlations.


title:
The diffuse neutrino flux from FR-II radio galaxies and blazars: A
  source property based estimate

abstract:
  Water and ice Cherenkov telescopes of the present and future aim for the
detection of a neutrino signal from extraterrestrial sources at energies E>PeV.
Some of the most promising extragalactic sources are Active Galactic Nuclei
(AGN). In this paper, the neutrino flux from two kinds of AGN sources will be
estimated assuming photohadronic interactions in the jet of the AGN. The first
analyzed sample contains FR-II radio galaxies while the second AGN type
examined are blazars. The result is highly dependent on the proton's index of
the energy spectrum. To normalize the spectrum, the connection between neutrino
and disk luminosity will be used by applying the jet-disk symbiosis model from
Falcke and Biermann (1995). The maximum proton energy and thus, also the
maximum neutrino energy of the source is connected to its disk luminosity,
which was shown by Lovelace (1976) and was confirmed by Falcke et al. (1995).


title: Dynamical and chemical properties of the "starless" core L1014

abstract:
  Spitzer Space Telescope observations of a point-like source, L1014-IRS, close
to the dust peak of the low-mass dense core L1014 have questioned its starless
nature. The presence of an object with colors expected for an embedded
protostar makes L1014-IRS the lowest luminosity isolated protostar known, and
an ideal target with which to test star formation theories at the low mass end.
In order to study its molecular content and to search for the presence of a
molecular outflow, we mapped L1014 in at least one transition of 12CO, N2H+,
HCO+, CS and of their isotopologues 13CO, C18O, C17O, N2D+ and H13CO+, using
the FCRAO, the IRAM 30 meter and the CSO. The data show physical and chemical
properties in L1014 typical of the less evolved starless cores: i.e. H2 central
density of a few 10^5 molecules cm^-3, estimated mass of ~2M_sun, CO integrated
depletion factor less than 10, N(N2H+)~6*10^12 cm^-2, N(N2D+)/N(N2H+) equal to
10% and relatively broad N2H+(1--0) lines (0.35 km/s). Infall signatures and
significant velocity shifts between optically thick and optically thin tracers
are not observed in the line profiles. No classical signatures of molecular
outflow are found in the 12CO and 13CO observations. In particular, no high
velocity wings are found, and no well-defined blue-red lobes of 12CO emission
are seen in the channel maps. If sensitive, higher resolution observations
confirm the absence of an outflow on a smaller scale than probed by our
observations, L1014-IRS would be the only protostellar object known to be
formed without driving an outflow.


title:
The first optical validation of an XLEO: a detection in the XMM-Newton
  observation of the CDFS

abstract:
  We present the first optical validation of an X-ray Line-Emitting Object
(XLEO) discovered in the XMM-Newton observation of the Chandra Deep Field
South. The object is an AGN at z_x ~ 0.66. An optical spectrum of the source
indeed confirms and refines (z_o = 0.665) the redshift obtained from the X-ray
line. The X-ray and optical properties of the source are presented and
discussed.


title: Envelope models for the supersoft X-ray emission of V1974 Cyg

abstract:
  The evolution of the soft X-ray emission of V1974 Cyg has been simulated by a
white dwarf envelope model with steady hydrogen burning. The comparison of the
results obtained from ROSAT observations with the results of our envelope
models indicates that the post-outburst evolution of the nova can be explained
by steady H-burning on either a 0.9 Msun white dwarf with 50% degree of mixing
between solar-like accreted material and the ONe degenerate core, or on a 1.0
Msun ONe white dwarf with 25% mixing.


title: Cosmic microwave background polarization analysis

abstract:
  With polarization of the cosmic microwave background (CMB) now detected, and
confirmed by several independent experiments, the next goal is to characterise
accurately its statistical properties. In these lecture notes we review the
physical motivation for pursuing CMB polarization, and the basic statistical
properties of the polarization fields. We then discuss some of the key aspects
of the analysis of CMB polarization data, focusing on the additional
complications that arise compared to temperature data due to the tensor
character of the polarization field.


title: Particle acceleration efficiencies in astrophysical shear flows

abstract:
  The acceleration of energetic particles in astrophysical shear flows is
analyzed. We show that in the presence of a non-relativistic gradual velocity
shear, power law particle momentum distributions $f(p) \propto p^{-(3+\alpha)}$
may be generated, assuming a momentum-dependent scattering time $\tau \propto
p^{\alpha}$, with $\alpha > 0$. We consider possible acceleration sites in
astrophysical jets and study the conditions for efficient acceleration. It is
shown, for example, that in the presence of a gradual shear flow and a
gyro-dependent particle mean free path, synchrotron radiation losses no longer
stop the acceleration once it has started to work efficiently. This suggests
that shear acceleration may naturally account for a second, non-thermal
population of energetic particles in addition to a shock-accelerated one. The
possible relevance of shear acceleration is briefly discussed with reference to
the relativistic jet in the quasar 3C 273.


title: The SCORPIO focal reducer

abstract:
  We describe the SCORPIO focal reducer that has been used since the fall of
2000 for observations on the 6-m Special Astrophysical Observatory telescope.
We give parameters of the instrument in various observing modes (direct images,
long-slit and multislit spectroscopy, spectropolarimetry, Fabry-Perot panoramic
spectroscopy). Observations of various astronomical objects are used as
examples to demonstrate the SCORPIO capabilities.


title:
Optical and Near-Infrared Integral Field Spectroscopy of the SCUBA
  Galaxy N2-850.4

abstract:
  We present optical and near-infrared integral field spectroscopy of the SCUBA
galaxy SMM J163650.43+405734.5 (ELAIS N2 850.4) at z=2.385. We combine Ly-alpha
and H-alpha emission line maps and velocity structure with high resolution HST
ACS and NICMOS imaging to probe the complex dynamics of this vigorous
star-burst galaxy. The imaging data shows a complex morphology, consisting of
at least three components separated by ~1'' (8kpc) in projection. When combined
with the H-alpha velocity field from UKIRT UIST IFU observations we identify
two components whose redshifts are coincident with the systemic redshift,
measured from previous CO observations, one of which shows signs of AGN
activity. A third component is offset by 220+/-50km/s from the systemic
velocity. The total star formation rate of the whole system (estimated from the
narrow-line H-alpha and uncorrected for reddening) is 340+/-50Mo/yr. The
Ly-alpha emission mapped by the GMOS IFU covers the complete galaxy and is
offset by +270+/-40km/s from the systemic velocity. This velocity offset is
comparable to that seen in rest-frame UV-selected galaxies at similar redshifts
and usually interpreted as a star-burst driven wind. The extended structure of
the Ly-alpha emission suggests that this wind is not a nuclear phenomenon, but
is instead a galactic scale outflow. Our observations suggest that the vigorous
activity in N2 850.4 is arising as a result of an interaction between at least
two dynamically-distinct components, resulting in a strong starburst, a
starburst-driven wind and actively-fuelled AGN activity. [abridged]


title:
Object classification and the determination of stellar parameters with
  Gaia

abstract:
  Gaia will observe more than one billion objects brighter than V=20, including
stars, asteroids, galaxies and quasars. As Gaia performs real time detection
(i.e. without an input catalogue) the intrinsic properties of most of these
objects will not be known a priori. An integral part of the Gaia data
processing is therefore to classify everything observed. This will be based
primarily on multiband photometry provided by Gaia, but should also make
optimal use of the high resolution spectroscopy (for brighter stars) and the
parallaxes. In addition to a broad classification, we can also determine
fundamental stellar parameters, in particular effective temperature,
metallicity and the line-of-sight interstellar extinction. Such information
will be essential for fully exploiting the astrometric part of the Gaia
catalogue for stellar population studies. However, extracting this information
is a significant challenge, and will need to make use of appropriate
multidimensional data analysis techniques. I outline some of the problems and
the strategies being developed to tackle them.


title: The broadening of Fe II lines by neutral hydrogen collisions

abstract:
  Data for the broadening of 24188 Fe II lines by collisions with neutral
hydrogen atoms have been computed using the theory of Anstee & O'Mara as
extended to singly ionised species and higher orbital angular momentum states
by Barklem & O'Mara. Data have been computed for all Fe II lines between
observed energy levels in the line lists of Kurucz with log gf > -5 for which
the theory is applicable. The variable energy debt parameter Ep used in
computing the second order perturbation theory potential is chosen to be
consistent with the long range dispersion interaction constant C6 computed
using the f-values from Kurucz.


title:
Design of the Gaia photometric systems for stellar parametrization using
  a population-based optimizer

abstract:
  Large, deep surveys must typically rely on multiband photometry rather than
spectroscopy for determining the astrophysical properties (APs) of stars. Yet
designing an optimal photometric system for a wide range of objects is complex,
because it must trade off conflicting scientific requirements. I present a new
method for designing photometric systems and apply it to the Gaia Galactic
survey satellite, which will observe one billion stars brighter than V=20. The
principle is to optimally sample stellar spectra in order to best determine the
APs (e.g. Teff, [Fe/H], interstellar extinction). By considering a filter
system as a set of free parameters (central wavelengths, FWHM etc.), it may be
designed by optimizing a figure-of-merit (FoM) with respect to these
parameters. The FoM is a measure of how well the filter system can vectorially
'separate' stars in the data space to avoid AP degeneracies. The resulting
systems show some interesting features, in particular broad, overlapping
filters, which may be desirable from a multivariate classification perspective.
These systems are competitive with others proposed for Gaia.


title:
Spitzer Identification of the Least Massive Known Brown Dwarf with a
  Circumstellar Disk

abstract:
  Using the Infrared Array Camera (IRAC) aboard the Spitzer Space Telescope, we
have obtained mid-infrared photometry of the least massive known brown dwarf in
the Chamaeleon I star-forming region. For this young brown dwarf, OTS 44, we
have constructed a spectral energy distribution (SED) from 0.8-8 um by
combining the measurements at 3.6, 4.5, 5.8, and 8.0 um from IRAC with
ground-based photometry at I, J, H, and K. The resulting SED for OTS 44
exhibits significant excess emission longward of 3 um relative to the SED
expected from the photosphere of the brown dwarf. We have successfully modeled
the source of this excess emission in terms of an irradiated viscous accretion
disk with M'<=10^-10 M_sun/year. With a spectral type of M9.5 and a mass of ~15
M_Jup, OTS 44 is now the coolest and least massive brown dwarf observed to have
a circumstellar disk. These measurements demonstrate that disks exist around
brown dwarfs even down to the deuterium burning mass limit and the approximate
upper mass limit of extrasolar planetary companions.


title:
The 3-D shaping of NGC 6741: a massive, fast-evolving Planetary Nebula
  at the recombination--reionization edge

abstract:
  We infer the gas kinematics, diagnostics and ionic radial profiles, distance
and central star parameters, nebular photo- ionization model, spatial structure
and evolutionary phase of the PN NGC 6741 by means of long-slit high-resolution
spectra at nine position angles. NGC 6741 (distance ~2.0 kpc, age ~1400 yr,
ionized mass Mion ~0.06 Mo) is a dense (electron density up to 12,000 cm^(-3)),
high-excitation, almost- prolate ellipsoid, surrounded by a sharp
low-excitation skin (the ionization front), and embedded into a spherical
(radius ~ 0.080 pc), almost-neutral, high-density (n(HI) ~7 x 10^3 atoms
cm^(-3)) halo containing a large fraction of the nebular mass (Mhalo>0.20 Mo).
The kinematics, physical conditions and ionic structure indicate that NGC 6741
is in a deep recombination phase, started about 200 years ago, and caused by
the quick luminosity drop of the massive (M*=0.66-0.68 Mo), hot (logT* ~ 5.23)
and faint (log L*/Lo ~ 2.75) post--AGB star, which has exhausted the
hydrogen-shell nuclear burning and is moving along the white dwarf cooling
sequence. The general expansion law of the ionized gas in NGC 6741, Vexp (km
s^(-1)=13 x R", fails in the innermost, highest-excitation layers, which move
slower than expected. The observed deceleration is ascribable to the luminosity
drop of the central star, and appears in striking contrast to recent reports
inferring that acceleration is a common property of the Planetary Nebulae
innermost layers. Some general implications on the shaping mechanisms of
Planetary Nebulae are discussed.


title:
The Interpretations For the Low and High Frequency QPO Correlations of
  X-ray Sources Among White Dwarfs, Neutron Stars and Black Holes

abstract:
  It is found that there exists an empirical linear relation between the high
frequency $\nhigh$ and low frequency $\nlow$ of quasi-periodic oscillations
(QPOs) for black hole candidate (BHC), neutron star (NS) and white dwarf (WD)
in the binary systems, which spans five orders of magnitude in frequency.
  For the NS Z (Atoll) sources,
  $\nu_{high}$ and $\nu_{low}$ are identified as the lower kHz QPO frequency
and horizontal branch oscillations (HBOs) $\nh$ (broad noise components); for
the black hole candidates and low-luminosity neutron stars, they are the QPOs
and broad noise components at frequencies between 1 and 10 Hz; for WDs, they
are the ``dwarf nova oscillations'' (DNOs) and QPOs of cataclysmic variables
(CVs). To interpret this relation, our model ascribes $\nu_{high}$ to the
Alfv\'en wave oscillation frequency at a preferred radius and $\nu_{low}$ to
the same mechanism at another radius. Then, we can obtain $\nlow = 0.08
  \nhigh$ and the relation between the upper kHz QPO frequency $\nt$ and HBO to
be $\nh \simeq 56 ({\rm Hz}) (\nt/{\rm kHz})^{2}$, which are in accordance with
the observed empirical relations. Furthermore, some implications of model are
discussed, including why QPO frequencies of white dwarfs and neutron stars span
five orders of magnitude in frequency. \\


title: Projection of circumstellar disks on their environments

abstract:
  We use a 3D Monte Carlo radiative transfer code to study the projection of
large shadows by circumstellar disks around young stellar objects on
surrounding reflection nebulosity. It is shown that for a wide range of
parameters a small (10-100 AU) circumstellar disk can project a large (1 000-10
000 AU) dark band in the near-infrared that often resembles a massive edge-on
disk. The disk shadows are divided into two basic types, depending on the
distribution of the reflecting material and the resulting morphology of the
shadows in the near-infrared. Two YSOs associated with bipolar nebulosity, CK
3/EC 82 illuminating the Serpens Reflection Nebula (SRN) and Ced 110 IRS 4 in
the Chamaeleon I molecular cloud, are modelled in detail as disk shadows.
Spectral energy distributions of the two sources are collected using both
archival ISO data and new Spitzer-IRS data. An axisymmetric model consisting of
a small disk and a spherically symmetric envelope can reproduce the
near-infrared images and full spectral energy distributions of the two disk
shadow candidates. It is shown that the model fits can be used to constrain the
geometry of the central disks due to the magnifying effect of the projection.
We find that a disk unresolved in near-infrared images, but casting a large
disk shadow, can be modelled at a level of sophistication approaching that of
an edge-on disk with resolved near-infrared images. It is found that the most
obvious observable difference between a disk shadow and a large optically thick
disk is that the disk shadows have a compact near-infrared source near the
center of the dark band. High resolution imaging and/or polarimetry should
reveal the compact source in the center of a disk shadow as an edge-on disk.
[Abstract abridged]


title:
Multidimensional Hydrodynamical Simulations of radiative cooling
  SNRs-clouds interactions: an application to Starburst Environments

abstract:
  In this work we are interested to study the by-products of SNR-clouds in a
starburst (SB) system. These interactions can have an important role in the
recycling of matter from the clouds to the ISM and vice-versa. In the present
work, we have focused our attention on the global effects of the interactions
between clouds and SN shock waves in the ISM of SB environments, and performed
3-D radiative cooling hydrodynamical simulations with the adaptive YGUAZU grid
code. We have also considered the effects of the photo-evaporation due to the
presence of a high number of UV photons from hot stars and supernovae (SNe).
The results have shown that, in the presence of radiative cooling, instead of
an efficient gas mixing with the diffuse ISM, the interactions cause the
fragmentation of the clouds into smaller ones. The results have also revealed
that the SNR-clouds interactions are less efficient at producing substantial
mass loss from the clouds to the diffuse ISM than mechanisms such as the
photo-evaporation caused by the UV flux from the hot stars.


title:
Exploring the Geometry, Topology and Morphology of Large Scale Structure
  using Minkowski Functionals

abstract:
  Modern redshift surveys such as the 2 degree field Galaxy Redshift Survey
(2dFGRS) and the Sloan Digital Sky Survey (SDSS) reveal the fully 3 dimensional
distribution of a million or so galaxies over a large cosmological volume.
Visually galaxies appear to be distributed along sheet-like and/or filamentary
superclusters. The CfA Great Wall, Southern Great Wall and the recently
discovered SDSS Great Wall are very spectacular superclusters. Clearly
theoretical predictions for galaxy clustering must be tested against these rich
datasets. This can be achieved by means of the Minkowski Functionals (MFs). A
MF-based approach provides an excellent description of superclusters and voids
and allows one to quantify the properties of the cosmic web. In this review we
give a summary of the progress made in this direction. After reviewing the
status of observations and of numerical simulations, we comment upon the nature
of bias which serves as a link between theoretical predictions and
observations. We also summarise the methods developed for efficient numerical
estimation of MFs for cosmological datasets and list several important results
obtained using these methods. Specifically, we stress the discriminatory power
of MFs and of the derived morphological statistics, the Shapefinders.
Shapefinders are an excellent tool with which to study the shapes and sizes of
superclusters and voids. We also discuss some of the important effects of
scale-dependent bias which are brought out by a MF-based study of the mock
catalogues of galaxies. Such effects, we note, should be accounted for before
comparing theoretical models with observations.


title:
The Binarity of Eta Carinae Revealed from Photoionization Modeling of
  the Spectral Variability of the Weigelt Blobs B and D

abstract:
  We focus on two Hubble Space Telescope/Space Telescope Imaging Spectrograph
(HST/STIS) spectra of the Weigelt Blobs B&D, extending from 1640 to 10400A; one
recorded during the 1998 minimum (March 1998) and the other recorded in
February 1999, early in the following broad maximum. The spatially-resolved
spectra suggest two distinct ionization regions. One structure is the
permanently low ionization cores of the Weigelt Blobs, B&D, located several
hundred AU from the ionizing source. Their spectra are dominated by emission
from H I, [N II], Fe II, [Fe II], Ni II, [Ni II], Cr II and Ti II. The second
region, relatively diffuse in character and located between the ionizing source
and the Weigelt Blobs, is more highly ionized with emission from [FeIII], [Fe
IV], N III], [Ne III], [Ar III], [Si III], [S III] and He I. Through
photoionization modeling, we find that the radiation field from the more
massive B-star companion supports the low ionization structure throughout the
5.54 year period. The radiation field of an evolved O-star is required to
produce the higher ionization emission seen across the broad maximum. This
emission region is identified with slow-moving condensations photoionized by
the O star and located in the extended mass flow emanating from the B star
primary. Comparison between the models and observations reveals that the high
ionization region is physically distinct (n_H ~ 10^7 cm^(-3) and T_e ~ 10^4K)
from the BD Blobs (n_H ~ 10^6 cm^(-3), T_e ~ 7000K).


title: The near-infrared excitation of the HH211 protostellar outflow

abstract:
  The protostellar outflow HH211 is of considerable interest since it is
extremely young and highly collimated. Here, we explore the outflow through
imaging and spectroscopy in the near-infrared to determine if there are further
diagnostic signatures of youth. We confirm the detection of a near-infrared
continuum of unknown origin. We propose that it is emitted by the driving
millimeter source, escapes the core through tunnels, and illuminates features
aligning the outflow. Narrow-band flux measurements of these features contain
an unusually large amount of continuum emission. [Fe II] emission has been
detected and is restricted to isolated condensations. However, the
characteristics of vibrational excitation of molecular hydrogen resemble those
of older molecular outflows. We attempt to model the ordered structure of the
western outflow as a series of shocks, finding that bow shocks with J-type
dissociative apices and C-type flanks are consistent. Moreover, essentially the
same conditions are predicted for all three bows except for a systematic
reduction in speed and density with distance from the driving source. We find
increased K-band extinctions in the bright regions as high as 2.9 magnitudes
and suggest that the bow shocks become visible where the outflow impacts on
dense clumps of cloud material. We propose that the outflow is carved out by
episodes of pulsating jets. The jets, driven by central explosive events, are
responsible for excavating a central tunnel through which radiation temporarily
penetrates.


title:
Mitigation of Pulsed Interference to Redshifted HI and OH Observations
  between 960 and 1215 MHz

abstract:
  The neutral hydrogen 21-cm spectral line (1420.4 MHz) and the four 18-cm
lines of the hydroxyl molecule (1612-1720 MHz) are observable at redshifts
which put their measured line frequencies well below their protected frequency
bands. Part of the redshift ranges (z = 0.171-0.477 for HI and z = 0.37-0.73
for OH) fall in the 960 to 1215 MHz band that is allocated to aircraft
navigation. Most of the signals in this band are pulsed emissions of low duty
cycle so much of the time between pulses is interference free. This paper
outlines the structure and measured properties of signals in this band and
demonstrates a signal processing strategy that is effective at removing the
pulsed signals from spectra at sensitivities produced by several hours of
integration.


title: Extreme X-ray Behavior of the Low-Luminosity Active Nucleus in NGC 4395

abstract:
  We present the results of a 17 ks Chandra ACIS-S observation of the nearby
dwarf spiral galaxy NGC 4395. Chandra affords the first high-quality, broadband
X-ray detection of the active nucleus of this object that is uncontaminated by
nearby sources in the field. We find the nuclear X-ray source to be unresolved
and confirm the rapid, large-amplitude variability reported in previous
studies. The light curve appears to show ~ 11 cycles of a quasi-periodic
oscillation with a period of ~ 400 s. If associated with an orbital feature
near the innermost stable orbit of the accretion disk, this period would
constrain the black-hole mass to be M < 9e5 M_sun. The X-ray spectrum indicates
absorption by an ionized medium, and the spectral shape appears to vary over
the course of our observation. Contrary to prior reports, however, the spectral
variations are uncorrelated with changes in the hard X-ray flux. It is possible
that the short-term spectral variability we observe results from column density
fluctuations in the ionized absorber. A power-law fit to the spectrum above 1
keV yields a photon index of Gamma ~ 0.6, much flatter than that typically
observed in the spectra of Seyfert 1 galaxies. We have ruled out photon pile-up
as the cause of the flat spectrum. Even when complex spectral features are
considered, the photon index is constrained to be Gamma < 1.25 (90%
confidence). Comparing our results with previous determinations of the photon
index (Gamma = 1.46 and 1.72), we conclude that the slope of the primary
continuum varies significantly on time scales of a year or less. The extreme
flatness and dramatic long-term variability of the X-ray spectrum are
unprecedented among active galactic nuclei.


title:
Cosmic Microwave Background, Accelerating Universe and Inhomogeneous
  Cosmology

abstract:
  We consider a cosmology in which a spherically symmetric large scale
inhomogeneous enhancement or a void are described by an inhomogeneous metric
and Einstein's gravitational equations. For a flat matter dominated universe
the inhomogeneous equations lead to luminosity distance and Hubble constant
formulas that depend on the location of the observer. For a general
inhomogeneous solution, it is possible for the deceleration parameter to differ
significantly from the FLRW result. The deceleration parameter $q_0$ can be
interpreted as $q_0 > 0$ ($q_0=1/2$ for a flat matter dominated universe) in a
FLRW universe and be $q_0 < 0$ as inferred from the inhomogeneous enhancement
that is embedded in a FLRW universe. A spatial volume averaging of local
regions in the backward light cone has to be performed for the inhomogeneous
solution at late times to decide whether the decelerating parameter $q$ can be
negative for a positive energy condition. The CMB temperature fluctuations
across the sky can be unevenly distributed in the northern and southern
hemispheres in the inhomogeneous matter dominated solution, in agreement with
the analysis of the WMAP power spectrum data by several authors. The model can
possibly explain the anomalous alignment of the quadrupole and octopole moments
observed in the WMAP data.


title: Merger-Induced Starbursts

abstract:
  Extragalactic starbursts induced by gravitational interactions can now be
studied from z = ~0 to ~2. The evidence that mergers of gas-rich galaxies tend
to trigger galaxy-wide starbursts is strong, both statistically and in
individual cases of major disk-disk mergers. Star formation rates appear
enhanced by factors of a few to ~10^3 above normal. Detailed studies of nearby
mergers and ULIRGs suggest that the main trigger for starbursts is the rapidly
mounting pressure of the ISM in extended shock regions, rather than high-
velocity, ~50 - 100 km/s cloud-cloud collisions. Numerical simulations
demonstrate that in colliding galaxies the star formation rate depends not only
on the gas density, but crucially also on energy dissipation in shocks. An
often overlooked characteristic of merger-induced starbursts is that the
spatial distribution of the enhanced star formation extends over large scales
(~10 - 20 kpc). Thus, although most such starbursts do peak near the galactic
centers, young stellar populations pervade merger remnants and explain why (1)
age gradients in descendent galaxies are mild and (2) resultant cluster systems
are far-flung. This review presents an overview of interesting phenomena
observed in galaxy-wide starbursts and emphasizes that such events continue to
accompany the birth of elliptical galaxies to the present epoch.


title: Non-linear X-ray variability in X-ray binaries and active galaxies

abstract:
  We show that the rms-flux relation recently discovered in the X-ray light
curves of Active Galactic Nuclei (AGN) and X-ray binaries (XRBs) implies that
the light curves have a formally non-linear, exponential form, provided the
rms-flux relation applies to variations on all time-scales (as it appears to).
This phenomenological model implies that stationary data will have a lognormal
flux distribution. We confirm this result using an observation of Cyg X-1, and
further demonstrate that our model predicts the existence of the powerful
millisecond flares observed in Cyg X-1 in the low/hard state, and explains the
general shape and amplitude of the bicoherence spectrum in that source. Our
model predicts that the most variable light curves will show the most extreme
non-linearity. This result can naturally explain the apparent non-linear
variability observed in some highly variable Narrow Line Seyfert 1 (NLS1)
galaxies, as well as the low states observed on long time-scales in the NLS1
NGC 4051, as being nothing more than extreme manifestations of the same
variability process that is observed in XRBs and less variable AGN. That
variability process must be multiplicative (with variations coupled together on
all time-scales) and cannot be additive (such as shot-noise), or related to
self-organised criticality, or result from completely independent variations in
many separate emitting regions. Successful models for variability must
reproduce the observed rms-flux relation and non-linear behaviour, which are
more fundamental characteristics of the variability process than the power
spectrum or spectral-timing properties. Models where X-ray variability is
driven by accretion rate variations produced at different radii remain the most
promising.


title:
Fluctuating annihilation cross sections and the generation of density
  perturbations

abstract:
  Fluctuations in the mass and decay rate of a heavy particle which for some
period dominates the energy density of the universe are known to lead to
adiabatic density perturbations. We show that generically the annihilation
cross section of the same particle also receives fluctuations, which leads to
entropy perturbations at freeze-out. If the particle comes to dominate the
energy density of the universe and subsequently decays, this leads to an
additional source of adiabatic density perturbations. On the other hand,
non-adiabatic density perturbations result when the particle does not decay but
contributes to the observed dark matter.


title: A Multi-wavelength Study of the X-ray Sources in NGC 5018

abstract:
  The E3 giant elliptical galaxy NGC5018 was observed with the Chandra X-ray
Observatory on 14 April 2001. Results of analysis of these X-ray data as well
as of complementary optical, infrared, and radio data are reported. Seven X-ray
point sources, including the nucleus, were detected.If they are intrinsic to
NGC5018, then all six non-nuclear sources have luminosities exceeding E+39
ergs/s in the 0.5-8.0 keV energy band; placing them in the class of
Ultra-luminous X-ray sources. Comparison of X-ray source positions to archival
HST/WFPC2 images reveal four of the six non-nuclear sources are
spatially-coincident with bright, absolute-magnitude (V) around -8.6 mag,
objects. These four objects have optical magnitudes and (V-I) colors consistent
with globular clusters in NGC5018 but they also have X-ray-to-optical flux
ratios consistent with background active galactic nuclei. Strong, unpolarized,
radio emission has been detected from one of the optically-bright counterparts.
Another optically-bright counterpart was observed to vary by one mag in optical
observations taken 28 July 1997 and 04 Feb 1999. Extended X-ray emission is
detected within a 15"radius of the galaxy center at a luminosity of E+40 ergs/s
in the X-ray band. Its thermal X-ray spectrum (kT around 0.4 keV) and its
spatial coincidence with strong H_alpha emission are consistent with a hot gas
origin. The nucleus itself may be a weak X-ray source, around E+39 ergs/s, that
displays a radio spectrum typical of AGN.


title: Are quasar jets dominated by Poynting flux?

abstract:
  The formation of relativistic astrophysical jets is presumably mediated by
magnetic fields threading accretion disks and central, rapidly rotating
objects. As it is accelerated by magnetic stresses, the jet's kinetic energy
flux grows at the expense of its Poynting flux. However, it is unclear how
efficient is the conversion from magnetic to kinetic energy and whether there
are any observational signatures of this process. We address this issue in the
context of jets in quasars. Using data from all spatial scales, we demonstrate
that in these objects the conversion from Poynting-flux-dominated to
matter-dominated jets is very likely to take place closer to the black hole
than the region where most of the Doppler boosted radiation observed in blazars
is produced. We briefly discuss the possibility that blazar activity can be
induced by global MHD instabilities, e.g., via the production of localized
velocity gradients that lead to dissipative events such as shocks or magnetic
reconnection, where acceleration of relativistic particles and production of
non-thermal flares is taking place.


title:
Rotochemical Heating in Millisecond Pulsars. Formalism and
  Non-superfluid case

abstract:
  Rotochemical heating originates in a departure from beta equilibrium due to
spin-down compression in a rotating neutron star. The main consequence is that
the star eventually arrives at a quasi-equilibrium state, in which the thermal
photon luminosity depends only on the current value of the spin-down power,
which is directly measurable. Only in millisecond pulsars the spin-down power
remains high long enough for this state to be reached with a substantial
luminosity. We report an extensive study of the effect of this heating
mechanism on the thermal evolution of millisecond pulsars, developing a general
formalism in the slow-rotation approximation of general relativity that takes
the spatial structure of the star fully into account, and using a sample of
realistic equations of state to solve the non-superfluid case numerically. We
show that nearly all observed millisecond pulsars are very likely to be in the
quasi-equilibrium state. Our predicted quasi-equilibrium temperatures for PSR
J0437-4715 are only 20% lower than inferred from observations. Accounting for
superfluidity should increase the predicted value.


title: The Colours of Elliptical galaxies

abstract:
  We have compiled a sample of 2728 nearby ($z<0.08$) elliptical galaxies with
photometry in the $g,r,i,z$ bands from the Sloan Digital Sky Survey (SDSS) and
$J,H,K$ photometry from the Two Micron All Sky Survey (2MASS). Stellar masses,
stellar velocity dispersions and structural parameters such as sizes and
surface mass densities are also available for these objects. In order to
correct the aperture mismatch between SDSS and 2MASS, we correct the SDSS
magnitudes to the isophotal circular radius where the 2MASS magnitudes are
measured. We compare the correlations between optical, optical-infrared and
infrared colours and galaxy luminosity, stellar mass, velocity dispersion and
surface mass density. We find that all galaxy colours correlate more strongly
with stellar mass and velocity dispersion than with any other structural
parameter. The dispersion about these two relations is also smaller.
  We also study the correlations between a variety of stellar absorption line
indices and the same set of galaxy parameters and we reach very similar
conclusions. Finally, we analyze correlations between absorption line indices
and colour. Our results suggest that the optical colours of elliptical galaxies
are sensitive to a combination of age, metallicity and $\alpha$-enhancement,
while the optical-infrared colours are sensitive to metallicity and to
$\alpha$-enhancement, but are somewhat less sensitive to age.


title:
Dark Matter Halos: Shapes, The Substructure Crisis, and Indirect
  Detection

abstract:
  In this proceeding, we briefly review three recent results. First, we show
that halos formed in simulations with gas cooling are significantly rounder
than halos formed in dissipationless $N$-body simulations. The increase in
principle axis ratios is $\delta (c/a) ~ 0.2 - 0.4$ in the inner halo and
remains significant at large radii. Second, we discuss the CDM substructure
crisis and demonstrate the sensitivity of the crisis to the spectrum of
primordial density fluctuations on small scales. Third, we assess the ability
of experiments like VERITAS and GLAST to detect $\gamma$-rays from neutralino
dark matter annihilation in dark subhalos about the MW.


title:
Nonsingular density profiles of dark matter halos and Strong
  gravitational lensing

abstract:
  We use the statistics of strong gravitational lenses to investigate whether
mass profiles with a flat density core are supported. The probability for
lensing by halos modeled by a nonsingular truncated isothermal sphere (NTIS)
with image separations greater than a certain value (ranging from zero to ten
arcseconds) is calculated. NTIS is an analytical model for the postcollapse
equilibrium structure of virialized objects derived by Shapiro, Iliev & Raga.
This profile has a soft core and matches quite well with the mass profiles of
dark matter-dominated dwarf galaxies deduced from their observed rotation
curves. It also agrees well with the NFW (Navarro-Frenk-White) profile at all
radii outside of a few NTIS core radii. Unfortunately, comparing the results
with those for singular lensing halos (NFW and SIS+NFW) and strong lensing
observations, the probabilities for lensing by NTIS halos are far too low. As
this result is valid for any other nonsingular density profiles (with a large
core radius), we conclude that nonsingular density profiles (with a large core
radius) for CDM halos are ruled out by statistics of strong gravitational
lenses.


title:
The Mauna Kea Observatories Near-Infrared Filter Set. III. Isophotal
  Wavelengths and Absolute Calibration

abstract:
  The isophotal wavelengths, flux densities, and AB magnitudes for Vega (alpha
Lyr) are presented for the Mauna Kea Observatories near-infrared filter set. We
show that the near-infrared absolute calibration for Vega determined by Cohen
et al. and Megessier are consistent within the uncertainties, so that either
absolute calibration may be used.


title: Two-mirror Schwarzschild aplanats. Basic relations

abstract:
  It is shown that the theory of aplanatic two-mirror telescopes developed by
Karl Schwarzschild in 1905 leads to the unified description both the prefocal
and the postfocal systems. The class of surfaces in the ZEMAX optical program
has been properly extended to ascertain the image quality in exact
Schwarzschild aplanats. A comparison of Schwarzschild aplanats with approximate
Ritchey-Chretien and Gregory-Maksutov aplanatic telescopes reveals a noticeable
advantage of the former at fast focal ratio of the system.


title: Relativistic Binary Pulsars with Black-Hole Companions

abstract:
  Binaries containing a stellar-mass black hole and a recycled radio pulsar
have so far eluded detection. We present a focused investigation of the
formation and evolution of these systems in the Galactic disk, highlighting the
factors that limit their numbers and the reasons why they may be extremely
rare. We surmise that the birthrate of black-hole/recycled-pulsar binaries in
the Galactic disk is probably no higher than ~10^{-7}/yr, and may be much less.
Simple arguments regarding common-envelope evolution suggest that these
binaries should have orbital periods less than 10 hr and an average lifetime of
<~10^8 yr before coalescence due to the emission of gravitational radiation. We
expect that fewer than ~10 of these compact, relativistic binaries currently
reside in the Galactic disk, less than 0.1--1% of the number of double neutron
stars. The discovery of two or more black-hole/recycled-pulsar binaries using
current radio telescopes would tightly constrain certain ideas regarding the
evolution of massive stars, dynamical mass transfer, and black-hole formation.


title: Multi-epoch infrared photometry of the star forming region G173.58+2.45

abstract:
  We present a multi-epoch infrared photometric study of the intermediate-mass
star forming region G173.58+2.45. Photometric observations are obtained using
the near-infrared $JHKL'M'$ filters and narrow-band filters centered at the
wavelengths of H$_2$ (1-0) S(1) (2.122 $\mu$m) and [FeII] (1.644 $\mu$m) lines.
The H$_2$ image shows molecular emission from shocked gas, implying the
presence of multiple star formation and associated outflow activity. We see
evidence for several collimated outflows. The most extended jet is at least
0.25 pc in length and has a collimation factor of $\sim$ 10, which may be
associated with a binary system within the central cluster, resolved for the
first time here. This outflow is found to be episodic; probably occurring or
getting enhanced during the periastron passage of the binary. We also find that
the variable star in the vicinity of the outflow source, which was known as a
FU Ori type star, is probably not a FU Ori object. However, it does drive a
spectacular outflow and the variability is likely to be related to accretion,
when large clouds of gas and dust spiral in towards the central source. Many
other convincing accretion-outflow systems and YSO candidates are discovered in
the field.