title: A Physical Model for the joint evolution of high-z QSOs and Spheroids

abstract:
  We summarize our physical model for the early co-evolution of spheroidal
galaxies and of active nuclei at their centers. Our predictions are in
excellent agreement with a number of observables which proved to be extremely
challenging for all the current semi-analytic models, including the sub-mm
counts and the corresponding redshift distributions, and the epoch-dependent
K-band luminosity function of spheroidal galaxies. Also, the black hole mass
function and the relationship between the black hole mass and the velocity
dispersion in the galaxy are nicely reproduced. The mild AGN activity revealed
by X-ray observations of SCUBA sources is in keeping with our scenario, and
testify the build up of SMBH triggered by intense star formation.


title: A Black Hole in the Galactic Center Complex IRS 13E?

abstract:
  The IRS 13E complex is an unusual concentration of massive, early-type stars
at a projected distance of ~0.13 pc from the Milky Way's central supermassive
black hole Sagittarius A* (Sgr A*). Because of their similar proper motion and
their common nature as massive, young stars it has recently been suggested that
IRS 13E may be the remnant of a massive stellar cluster containing an
intermediate-mass black hole (IMBH) that binds its members gravitationally in
the tidal field of Sgr A*. Here, we present an analysis of the proper motions
in the IRS~13E environment that combines the currently best available data with
a time line of 10 years. We find that an IMBH in IRS 13E must have a minimum
mass of ~10^4 solar masses in order to bind the source complex gravitationally.
This high mass limit in combination with the absence so far of compelling
evidence for a non-thermal radio and X-ray source in IRS 13E make it appear
unlikely that an IMBH exists in IRS 13E that is sufficiently massive to bind
the system gravitationally.


title:
Spectroscopic study of the long-period dust-producing WC7pd+O9 binary
  HD192641

abstract:
  We present the results of an optical spectroscopic study of the massive
Wolf-Rayet binary WR137. These data cover the dust-formation maximum in 1997.
Combining all available measurements of radial velocities, we derive, for the
first time, a spectroscopic orbit with period 13.05 +/- 0.18 years. The
resulting masses, adopting i=67degrees, are M(O)= 20 +/- 2 Mo and M(WR)= 4.4+/-
1.5 Mo. These appear, respectively, around normal and on the low side for the
given spectral types. Analysis of the intense multi-site spectroscopic
monitoring in 1999 shows that the CIII5696 and CIV5802/12 lines have the
highest intrinsic variability levels. The periodogram analysis yields a
small-amplitude modulation in the absorption troughs of the CIV5802/12 and
HeI5876 lines with a period of 0.83 days, which could be related either to
pulsations or large-scale rotating structures as seen in the WN4 star EZ Canis
Majoris (WR6).Wavelet analysis of the strong emission lines of CIII5696 and
CIV5802/12 enabled us to isolate and follow for several hours small structures
associated with density enhancements within the wind of the Wolf-Rayet star.
Cross-correlating the variability patterns seen in different lines, we find a
weak but significant correlation between the varability in emission lines with
different ionization potential, i.e. in lines formed at different distances
from the WR stellar core. Adopting a beta wind-velocity law, from the motion of
individual subpeaks we find beta around 5, which is significantly larger than
the canonical value of 1 usually found in O-star winds.


title: Testing the Friedmannian magnitude-redshift relation with SNIa data

abstract:
  Standard cosmology is constructed upon the (generally implicit) assumption of
the ``large scale'' homogeneity of our Universe. Now, structures are observed
at scales which become larger and larger as the observational distances
increase. However, the homogeneous Friedmann-Lemaitre-Robertson-Walker model
remains a cosmological paradigm, and Friedmannian relations are usually used to
work out the model, implicitly assuming that the homogeneity assumption is
valid at the studied scales. This has been the way the concordance (Lambda-CDM)
model came out from the analyses of the SNIa data. Since this model implies the
validity of the Friedmannian magnitude-redshift relation at the range of
redshifts spaned by the supernovae surveys, it has been proposed some years ago
a very simple test of this possible validity, provided the SNIa should be
confirmed as standard candles. Since we can hope that the redshifts of the
supernovae which will be observed in the years to come will allow such a test
to be performed, it would be interesting to find inside the SNIa community some
collaborators ready to perform the test.


title:
The Cross-Correlation between Galaxies and Groups: Probing the Galaxy
  Distribution in and around Dark Matter Haloes

abstract:
  We determine the cross-correlation function between galaxies and galaxy
groups, using both the Two-Degree Field Galaxy Redshift Survey (2dFGRS) and the
Sloan Digital Sky Survey (SDSS). We study the cross-correlation as a function
of group mass, and as a function of the luminosity, stellar mass, colour,
spectral type and specific star formation rate of the galaxies. All these
cross-correlation functions show a clear transition from the `1-halo' to the
`2-halo' regimes on a scale comparable to the virial radius of the groups in
consideration. On scales larger than the virial radius, all cross-correlation
functions are roughly parallel, consistent with the linear bias model. In
particular, the large scale correlation amplitudes are higher for more massive
groups, and for brighter and redder galaxies. In the `1-halo' regime, the
cross-correlation function depends strongly on the definition of the group
center. We consider both a luminosity-weighted center (LWC) and a center
defined by the location of the brightest group galaxy (BGC). With the first
definition, the bright early-type galaxies in massive groups are found to be
more centrally concentrated than the fainter, late-type galaxies. Using the
BGC, and excluding the brightest galaxy from the cross correlation analysis, we
only find significant segregation in massive groups ($M \gta
10^{13}h^{-1}\msun$) for galaxies of different spectral types (or colours or
specific star formation rates). In haloes with masses $\la 10^{13}h^{-1}\msun$,
there is a significant deficit of bright satellite galaxies. Comparing the
results from the 2dFGRS with those obtained from realistic mock samples, we
find that the distribution of galaxies in groups is much less concentrated than
dark matter haloes predicted by the current $\Lambda$CDM model. (Abridged)


title: Weak Gravitational Flexion

abstract:
  Flexion is the significant third-order weak gravitational lensing effect
responsible for the weakly skewed and arc-like appearance of lensed galaxies.
Here we demonstrate how flexion measurements can be used to measure galaxy halo
density profiles and large-scale structure on non-linear scales, via
galaxy-galaxy lensing, dark matter mapping and cosmic flexion correlation
functions. We describe the origin of gravitational flexion, and discuss its
four components, two of which are first described here. We also introduce an
efficient complex formalism for all orders of lensing distortion. We proceed to
examine the flexion predictions for galaxy-galaxy lensing, examining isothermal
sphere and Navarro, Frenk & White (NFW) profiles and both circularly symmetric
and elliptical cases. We show that in combination with shear we can precisely
measure galaxy masses and NFW halo concentrations. We also show how flexion
measurements can be used to reconstruct mass maps in 2-D projection on the sky,
and in 3-D in combination with redshift data. Finally, we examine the
predictions for cosmic flexion, including convergence-flexion
cross-correlations, and find that the signal is an effective probe of structure
on non-linear scales.


title:
Constraining population synthesis models via the binary neutron star
  population

abstract:
  The observed sample of double neutron-star (NS-NS) binaries presents a
challenge to population-synthesis models of compact object formation: the
parameters entering into these models must be carefully chosen so as to match
(i) the observed star formation rate and (ii) the formation rate of NS-NS
binaries, which can be estimated from the observed sample and the selection
effects related to the discoveries with radio-pulsar surveys. In this paper, we
select from an extremely broad family of possible population synthesis models
those few (2%) which are consistent with the observed sample of NS-NS binaries.
To further sharpen the constraints the observed NS-NS population places upon
our understanding of compact-object formation processes, we separate the
observed NS-NS population into two channels: (i) merging NS-NS binaries, which
will inspiral and merge through the action of gravitational waves within $10 $
Gyr, and (ii) wide NS-NS binaries, consisting of all the rest. With the subset
of astrophysically consistent models, we explore the implications for the rates
at which double black hole (BH-BH), black hole-neutron star (BH-NS), and NS-NS
binaries will merge through the emission of gravitational waves.


title:
The Magnetic Field in Galaxies, Galaxy Clusters, and the InterGalactic
  Space

abstract:
  Magnetic fields of debated origin appear to permeate the Universe on all
large scales. There is mounting evidence that supernovae produce not only
roughly spherical ejecta and winds, but also highly relativistic jets of
ordinary matter. These jets, which travel long distances, slow down by
accelerating the matter encountered on their path to cosmic-ray energies. We
show that, if the turbulent motions induced by the winds and the cosmic rays
generate magnetic fields in rough energy equipartition, the predicted
magnetic-field strengths coincide with the ones observed not only in galaxies
(5 $\mu$G in the Milky Way) but also in galaxy clusters (6 $\mu$G in Coma). The
prediction for the intergalactic (or inter-cluster) field is 50 nG.


title:
A Definitive Measurement of Time Dilation in the Spectral Evolution of
  the Moderate-Redshift Type Ia Supernova 1997ex

abstract:
  We have obtained high-quality Keck optical spectra at three epochs of the
Type Ia supernova 1997ex, whose redshift z is 0.361. The elapsed calendar time
between the first two spectra was 24.88 d, and that between the first and third
spectra was 30.95 d. In an expanding universe where 1 + z represents the factor
by which space has expanded between the emission and detection of light, the
amount of aging in the supernova rest frame should be a factor of 1 / (1 + z)
smaller than the observed-frame aging; thus, we expect SN 1997ex to have aged
18.28 d and 22.74 d between the first epoch and the second and third epochs,
respectively. The quantitative method for determining the spectral-feature age
of a SN Ia, developed by Riess et al. (1997), reveals that the corresponding
elapsed times in the supernova rest frame were 16.97 +/- 2.75 d and 18.01 +/-
3.14 d, respectively. This result is inconsistent with no time dilation with a
significance level of 99.0%, providing evidence against "tired light" and other
hypotheses in which no time dilation is expected. Moreover, the observed
timescale of spectral evolution is inconsistent with that expected in the
"variable mass theory." The result is within ~1 sigma of the aging expected
from a universe in which redshift is produced by cosmic expansion.


title: Infrared Imaging of Capella with the IOTA Closure Phase Interferometer

abstract:
  We present infrared aperture synthesis maps produced with the upgraded IOTA
interferometer. Michelson interferograms on the close binary system Capella
(Alpha Aur) were obtained in the H-band between 2002 November 12 and 16 using
the IONIC3 beam combiner. With baselines of 15m < B < 38m, we were able to
determine the relative position of the binary components with milliarcsecond
(mas) precision and to track their movement along the approx. 14 degree arc
covered by our observation run. We briefly describe the algorithms used for
visibility and closure phase estimation. Three different Hybrid Mapping and
Bispectrum Fitting techniques were implemented within one software framework
and used to reconstruct the source brightness distribution. By dividing our
data into subsets, the system could be mapped at three epochs, revealing the
motion of the stars. The precise position of the binary components was also
determined with model fits, which in addition revealed I_Aa/I_Ab=1.49 +/- 0.10
and apparent stellar uniform-disk (UD) diameters of Theta_Aa=8.9 +/- 0.6 mas
and Theta_Ab=5.8 +/- 0.8 mas.
  To improve the u, v-plane coverage, we compensated this orbital motion by
applying a rotation-compensating coordinate transformation. The resulting
model-independent map with a beam size of 5.4 x 2.6 mas allows the resolution
of the stellar surfaces of the Capella giants themselves.


title:
Confidence limits of evolutionary synthesis models. IV Moving forward to
  a probabilistic formulation

abstract:
  Synthesis models predict the integrated properties of stellar populations.
Several problems exist in this field, mostly related to the fact that
integrated properties are distributed. To date, this aspect has been either
ignored (as in standard synthesis models, which are inherently deterministic)
or interpreted phenomenologically (as in Monte Carlo simulations, which
describe distributed properties rather than explain them). We approach
population synthesis as a problem in probability theory, in which stellar
luminosities are random variables extracted from the stellar luminosity
distribution function (sLDF). We derive the population LDF (pLDF) for clusters
of any size from the sLDF, obtaining the scale relations that link the sLDF to
the pLDF. We recover the predictions of standard synthesis models, which are
shown to compute the mean of the sLDF. We provide diagnostic diagrams and a
simplified recipe for testing the statistical richness of observed clusters,
thereby assessing whether standard synthesis models can be safely used or a
statistical treatment is mandatory. We also recover the predictions of Monte
Carlo simulations, with the additional bonus of being able to interpret them in
mathematical and physical terms. We give examples of problems that can be
addressed through our probabilistic formalism. Though still under development,
ours is a powerful approach to population synthesis. In an era of resolved
observations and pipelined analyses of large surveys, this paper is offered as
a signpost in the field of stellar populations.


title:
The Relationship Between Luminosity and Broad-Line Region Size in Active
  Galactic Nuclei

abstract:
  We reinvestigate the relationship between the characteristic broad-line
region size (R_blr) and the Balmer emission-line, X-ray, UV, and optical
continuum luminosities. Our study makes use of the best available
determinations of R_blr for a large number of active galactic nuclei (AGNs)
from Peterson et al. Using their determinations of R_blr for a large sample of
AGNs and two different regression methods, we investigate the robustness of our
correlation results as a function of data sub-sample and regression technique.
Though small systematic differences were found depending on the method of
analysis, our results are generally consistent. Assuming a power-law relation
R_blr \propto L^\alpha, we find the mean best-fitting \alpha is about
0.67+/-0.05 for the optical continuum and the broad H\beta luminosity, about
0.56+/-0.05 for the UV continuum luminosity, and about 0.70+/-0.14 for the
X-ray luminosity. We also find an intrinsic scatter of about 40% in these
relations. The disagreement of our results with the theoretical expected slope
of 0.5 indicates that the simple assumption of all AGNs having on average same
ionization parameter, BLR density, column density, and ionizing spectral energy
distribution, is not valid and there is likely some evolution of a few of these
characteristics along the luminosity scale.


title:
An Analytic Model of Environmental Effects on Cosmic Structure Formation
  and an Application to Cosmic Accretion Shocks

abstract:
  We present a new analytic tool for the study of cosmic structure formation, a
double distribution of the number density of dark matter halos with respect to
both halo mass and local over- (or under-) density. The double distribution
provides a statistical treatment of the properties of matter surrounding
collapsed objects, and can be used to provide analytical insight into
environmental effects on hierarchical structure formation. We apply this new
tool to the case of cosmic accretion shocks. We investigate and quantify the
effect of environmental factors on the statistical properties of these shocks.
For this purpose, we explore two different models. The first control model uses
a Press-Schechter mass function to describe the population of collapsed
structures, and assumes that all objects accrete gas of the same density and
temperature. The second model treats the accreted material as a
multi-temperature, multi-density medium with densities and temperatures derived
from the double distribution. We find that the shock environment significantly
alters the physical impact of cosmic accretion shocks on the intergalactic
medium, as well as the cosmic history of their properties.


title: E = mc^2 Without Relativity

abstract:
  The equivalence of mass and energy is indelibly linked with relativity, both
by scientists and in the popular mind. I prove that E = mc^2 by demanding
momentum conservation of an object that emits two equal electromagnetic wave
packets in opposite directions in its own frame. In contrast to Einstein's
derivation of this equation, which applies energy conservation to a similar
thought experiment, the new derivation employs no effects that are greater than
first order in v/c and therefore does not rely on results from Special
Relativity. In addition to momentum conservation, it uses only aberration of
starlight and the electromagnetic-wave momentum-energy relation p=E/c, both of
which were established by 1884. In particular, no assumption is made about the
constancy of the speed of light, and the derivation proceeds equally well if
one assumes that light is governed by a Galilean transformation. In view of
this, it is somewhat puzzling that the equivalence of mass and energy was not
derived well before the advent of Special Relativity. The new derivation is
simpler and more transparent than Einstein's and is therefore pedagogically
useful.


title:
Pushing the Limits of Ground-Based Photometric Precision --
  Sub-Millimagnitude Time-Series Photometry of the Open Cluster NGC 6791

abstract:
  We present the results from a three night, time-series study of the open
cluster NGC 6791 using the Megacam wide-field mosaic CCD camera on the 6.5m MMT
telescope. The aim of this study was to demonstrate the ability to obtain very
high precision photometry for a large number of stars. We achieved better than
1% precision for more than 8000 stars with 14.3 < R < 20.1 and
sub-millimagnitude (as low as 0.36 mmag) precision for over 300 stars with 14.6
< R < 16.3 in the field of this cluster. We also discovered 8 new variable
stars, including a possible delta-Scuti variable with an amplitude of 2%, 6
likely W UMa contact binaries, and a possible RS CVn star, and we identified 5
suspected low-amplitude variables, including one star with an amplitude of 3
mmag. We comment on the implications of this study for a ground-based survey
for transiting planets as small as Neptune.


title:
From Dusty Filaments to Cores to Stars: An Infrared Extinction Study of
  Lupus 3

abstract:
  We present deep NIR observations of a dense region of Lupus 3 obtained with
ESO's NTT and VLT. Using the NICE method we construct a dust extinction map of
the cloud, which reveals embedded globules, a dense filament, and a dense ring
structure. We derive dust column densities and masses for the entire cloud and
for the individual structures therein. We construct radial extinction profiles
for the embedded globules and find a range of profile shapes from relatively
shallow profiles for cores with low peak extinctions, to relatively steep
profiles for cores with high extinction. Overall the profiles are similar to
those of pressure truncated isothermal spheres of varying center-to-edge
density contrast. We apply Bonnor-Ebert analysis to compare the density
profiles of the embedded cores in a quantitative manner and derive physical
parameters such as temperatures, central densities, and external pressures. We
examine the stability of the cores and find that two cores are likely stable
and two are likely unstable. One of these latter cores is known to harbor an
active protostar. Finally, we discuss the relation between an emerging cluster
in Lupus 3 and the ring structure identified in our extinction map. Assuming
that the ring is the remnant of the core within which the cluster originally
formed we estimate that a star formation efficiency of ~ 30% characterized the
formation of the small cluster. Our observations of Lupus 3 suggest an intimate
link between the structure of a dense core and its state of star forming
activity. The dense cores are found to span the entire range of evolution from
a stable, starless core of modest central concentration, to an unstable,
star-forming core which is highly centrally concentrated, to a significantly
disrupted core from which a cluster of young stars is emerging.


title: The Galex Ultraviolet Variability (GUVV) Catalog

abstract:
  We present Version 1.0 of the NASA Galaxy Evolution Explorer (GALEX)
ultraviolet variability catalog (GUVV) that contains information on 84
time-variable and transient sources gained with simultaneous near and far
ultraviolet photometric observations. These time-variable sources were
serendipitously revealed in the various 1.2 degree star fields currently being
surveyed by the GALEX satellite in two ultraviolet bands (NUV 1750-2750A, FUV
1350-1750A) with limiting AB magnitudes of 23-25. The largest-amplitude
variable objects presently detected by GALEX are M-dwarf flare stars, which can
brighten by 5-10 mag in both the NUV and FUV bands during short duration (<
500s) outbursts. Other types of large-amplitude ultraviolet variable objects
include ab-type RR Lyrae stars, which can vary periodically by 2-5mag in the
GALEX FUV band. This first GUVV catalog lists galactic positions and possible
source identifications in order to provide the astronomical community with a
list of time-variable objects that can now be repeatedly observed at other
wavelengths. We expect the total number of time-variable source detections to
increase as the GALEX mission progresses, such that later version numbers of
the GUVV catalog will contain substantially more variable sources.


title: A New Detached M Dwarf Eclipsing Binary

abstract:
  We describe a newly-discovered detached M-dwarf eclipsing binary system, the
fourth such system known. This system was first observed by the TrES network
during a long term photometry campaign of 54 nights. Analysis of the folded
light curve indicates two very similar components orbiting each other with a
period of 1.12079 +/- 0.00001 days. Spectroscopic observations with the
Hobby-Eberly Telescope show the system to consist of two M3e dwarfs in a
near-circular orbit. Double-line radial velocity amplitudes, combined with the
orbital inclination derived from light-curve fitting, yield Mass total = 0.983
+/- 0.007 solar masses, with component masses M(1) = 0.493 +/- 0.003 and M(2) =
0.489 +/- 0.003 solar masses. The light-curve fit yields component radii of
R(1) = 0.453 +/- 0.060 and R(2) = 0.452 +/- 0.050 solar radii. Though a precise
parallax is lacking, broadband VJHK colors and spectral typing suggest
component absolute magnitudes of M_V(1) = 11.18 +/- 0.30 and M_V(2) = 11.28 +/-
0.30.


title:
An Excess Due to Small Grains Around The Nearby K0V Star HD69830:
  Asteroid or Cometary Debris?

abstract:
  Spitzer photometry and spectroscopy of the star HD69830 reveal an excess of
emission relative to the stellar photosphere between 8 and 35 $\mu$m dominated
by strong features attributable to crystalline silicates with an emitting
surface area more than 1,000 times that of our zodiacal cloud. The spectrum
closely resembles that of the comet C/1995 O1 (Hale-Bopp). Since no excess is
detected at 70 $\mu$m, the emitting material must be quite warm, be confined
within a few AU of the star, and originate in grains with low long-wavelength
emissivity, i.e. grains much smaller than $70 \mu$m$/2\pi\sim 10 $ $\mu$m. The
strong mineralogical features are evidence for even smaller, possibly
sub-micron sized grains. This small grain size is in direct contrast to the
10-100 $\mu$m grains that dominate the relatively featureless spectra of our
zodiacal dust cloud and most other main sequence stars with excesses. The upper
limit at 70 $\mu$m also implies that any Kuiper Belt analog must either be very
cold or be less massive than $\sim$ 5 times our own Kuiper Belt.
  With collisional and Poynting-Robertson drag times of about a thousand years
for small grains, the emitting material must either: a) be created through
continual grinding down of material in a dense asteroid belt; or b) originate
in cometary debris arising from either a single ``super-comet'' or a very large
number of individual comets arriving from a distant reservoir. In the case of a
cometary origin for the emission, the mass requirements for continuous
generation by many individual comets are unreasonable and we favor the capture
of a single ``super comet'' into a 0.5-1 AU orbit where it can evolve a large
number of small grains over a 2 Myr period.


title: A New Wolf-Rayet Star and its Ring Nebula: PCG11

abstract:
  In a search for new Galactic planetary nebulae from our systematic scans of
the Anglo-Australian Observatory/United Kingdom Schmidt Telescope (AAO/UKST)
Halpha survey of the Southern Galactic Plane, we have identified a Pop I
Wolf-Rayet star of type WN7h associated with an unusual ring nebula that has a
fractured rim. We present imagery in Halpha, the 843-MHz continuum from the
Molonglo Observatory Synthesis Telescope (MOST), the mid-infrared from the
Midcourse Space Experiment (MSX), and confirmatory optical spectroscopy of the
character of the nebula and of its central star. The inner edge of the Halpha
shell shows gravitational instabilities with a well-defined wavelength around
its complete circumference.


title: Simulating a faint gamma-ray burst population

abstract:
  There have now been three supernova-associated gamma-ray bursts (GRBs) at
redshift z < 0.17, namely 980425, 030329, and 031203, but the nearby and
under-luminous GRBs 980425 and 031203 are distinctly different from the
`classical' or standard GRBs. It has been suggested that they could be
classical GRBs observed away from their jet axes, or they might belong to a
population of under-energetic GRBs. Recent radio observations of the afterglow
of GRB 980425 suggest that different engines may be responsible for the
observed diversity of cosmic explosions. Given this assumption, a crude
constraint on a luminosity function for faint GRBs with a mean luminosity
similar to that of GRB 980425 and an upper limit on the rate density of
980425-type events, we simulate the redshift distribution of under-luminous
GRBs assuming BATSE and Swift sensitivities. A local rate density of about 0.6%
of the local supernova Type Ib/c rate yields simulated probabilities for
under-luminous events to occur at rates comparable to the BATSE GRB
low-redshift distribution. In this scenario the probability of BATSE/HETE
detecting at least one GRB at z<0.05 is 0.78 over 4.5 years, a result that is
comparable with observation. Swift has the potential to detect 1--5
under-luminous GRBs during one year of observation.


title: The core of the Canis Major galaxy as traced by Red Clump stars

abstract:
  The recently-discovered stellar system in Canis Major is analysed using
He-burning Red Clump stars as tracers. Canis Major turns out to be the
strongest and most spatially confined overdensity of the whole Galactic Disc,
both in terms of number density and of statistical significance. When projected
onto the Galactic Plane, it appears as an elongated and compact overdensity
extending from l ~ 200 to l ~ 280 with a roundish core toward l ~ 240. We find
that the main body of the system has an integrated absolute magnitude M_V=-14.4
+/- 0.8, a central surface brightness \mu_{V,0} = 24.0 +/- 0.6 mag/arcsec^2 and
a line-of-sight profile peaked at D_{sun}=7.2 +/- 1.0 kpc with Half Width at
Half Maximum ~ 2.0 kpc, in excellent agreement with the results obtained with
widely different tracers (M giants and Main Sequence stars) in previous
analyses. The mean distance to the main body of Canis Major is observed to
increase with increasing Galactic longitude, from D_{sun} ~ 6.3 kpc at l ~ 225,
to D_{sun} ~ 9.3 kpc at l ~ 265, in good agreement with the predictions of our
more recent N-body simulation that models CMa as a dwarf galaxy being accreted
in a planar orbit onto the disc of the Milky Way. We confirm that the Canis
Major system has all the characteristics of the relic of a dwarf galaxy seen on
top of a large-scale overdensity that we detect all over the third and fourth
Galactic quadrants (180<l<360, with a strong maximum around l=290 and b> -5)
that is identified as the stellar component of the southern Galactic Warp...
(Abridged)....


title: On the excitation of PG1159-type pulsations

abstract:
  Stability properties are presented of dipole and quadrupole nonradial
oscillation modes of model stars that experienced a late helium shell flash on
their way to the white-dwarf cooling domain. The computed instability domains
are compared with the observed hot variable central stars of planetary nebulae
and the GW Vir pulsators.


title:
From young massive star cluster to old globular: the L_V-sigma_0
  relationship as a diagnostic tool

abstract:
  We present a new analysis of the properties of the young massive star
clusters, which demonstrates that these objects are plausible progenitors of
old globular clusters (GCs). The method is based on the tight relationship for
old GCs between their V-band luminosities and (central) velocity dispersions,
sigma_0. We improve the significance of the relationship and find that its
functional form, L_V/Lsun \propto sigma_0^(1.57 +- 0.10) (km/s), is fully
consistent with previous determinations for smaller Galactic and M31 GC
samples. The tightness of the relationship for a GC sample drawn from
environments as diverse as those found in the Local Group implies that its
origin must be sought in intrinsic properties of the GC formation process
itself. We evolve the luminosities of the young massive star clusters (YMCs) in
the local Universe to an age of 12 Gyr and find that most YMCs will evolve to
loci close to, or to slightly fainter luminosities than the improved GC
relationship. In the absence of significant external disturbances, this implies
that these objects may potentially survive to become old GC-type objects over a
Hubble time. The main advantage of our new method is its simplicity; the only
observables required here are the system's velocity dispersion and luminosity.
The most important factor affecting the robustness of our conclusions is the
adopted form of the initial mass function. We use N-body simulations to confirm
that dynamical evolution of the clusters does not significantly alter our
conclusions. [ABRIDGED]


title:
Search for Extra-Terrestrial planets: The DARWIN mission - Target Stars
  and Array Architectures

abstract:
  The DARWIN mission is an Infrared free flying interferometer mission based on
the new technique of nulling interferometry. Its main objective is to detect
and characterize other Earth-like planets, analyze the composition of their
atmospheres and their capability to sustain life, as we know it. DARWIN is
currently in definition phase. This PhD work that has been undertaken within
the DARWIN team at the European Space Agency (ESA) addresses two crucial
aspects of the mission. Firstly, a DARWIN target star list has been established
that includes characteristics of the target star sample that will be critical
for final mission design, such as, luminosity, distance, spectral
classification, stellar variability, multiplicity, location and radius of the
star. Constrains were applied as set by planet evolution theory and mission
architecture. Secondly, a number of alternative mission architectures have been
evaluated on the basis of interferometer response as a function of wavelength,
achievable modulation efficiency, number of telescopes and starlight rejection
capabilities. The study has shown that the core mission goals should be
achievable with a lower level of complexity as compared to the current baseline
configuration.


title: Gamma-Ray Emission from Microquasars

abstract:
  Microquasars, X-ray binary systems that generate relativistic jets, were
discovered in our Galaxy in the last decade of the XXth century. Their name
indicates that they are manifestations of the same physics as quasars but on a
completely different scale. Parallel to this discovery, the EGRET instrument on
board of the Compton Gamma Ray Observatory detected 271 point like gamma-ray
sources 170 of which were not clearly identified with known objects. This
marked the beginning of gamma-ray source population studies in the Galaxy. We
present in this thesis models for gamma-ray production in microquasars with the
aim to propose them as possible parent populations for different groups of
EGRET unidentified sources. These models are developed for a variety of
scenarios taking into account several possible combinations, i.e. black holes
or neutron stars as the compact object, low mass or high mass stellar
companions, as well as leptonic or hadronic gamma-ray production processes. We
also show that the presented models for gamma-rays emitting microquasars can be
used to explain observations from well known sources that are detected in
energy ranges other than EGRET's. Finally, we include an alternative gamma-ray
producing situation that does not involve microquasars but a specific
unidentified EGRET source possibly linked to a magnetized accreting pulsar.


title: Correlation of Low z Lyman-alpha Absorbers with HI-selected Galaxies

abstract:
  In this work, observational evidence for the connection between low column
density Lyman-alpha absorbers and large-scale structure traced by gas-rich
galaxies is investigated. The HI Parkes All Sky Survey (HIPASS) galaxy
catalogue is cross-correlated with known low redshift, low column density
Lyman-alpha absorbers from the literature. The absorber-galaxy
cross-correlation function shows that on scales from 1 to 10 h^-1 Mpc,
absorbers are imbedded in halos with masses similar to that of galaxy groups.
This statistical evidence suggests that galaxy groups could be the dominant
environment of low column density Lyman-alpha absorbers at z=0.


title:
On the Identification of High Mass Star Forming Regions using IRAS:
  Contamination by Low-Mass Protostars

abstract:
  We present the results of a survey of a small sample (14) of low-mass
protostars (L_IR < 10^3 Lsun) for 6.7 GHz methanol maser emission performed
using the ATNF Parkes radio telescope. No new masers were discovered. We find
that the lower luminosity limit for maser emission is near 10^3 Lsun, by
comparison of the sources in our sample with previously detected methanol maser
sources. We examine the IRAS properties of our sample and compare them with
sources previously observed for methanol maser emission, almost all of which
satisfy the Wood & Churchwell criterion for selecting candidate UCHII regions.
We find that about half of our sample satisfy this criterion, and in addition
almost all of this subgroup have integrated fluxes between 25 and 60 microns
that are similar to sources with detectable methanol maser emission. By
identifying a number of low-mass protostars in this work and from the
literature that satisfy the Wood & Churchwell criterion for candidate UCHII
regions, we show conclusively for the first time that the fainter flux end of
their sample is contaminated by lower-mass non-ionizing sources, confirming the
suggestion by van der Walt and Ramesh & Sridharan.


title: From Little Bangs to the Big Bang

abstract:
  The `Little Bangs' made in particle collider experiments reproduce the
conditions in the Big Bang when the age of the Universe was a fraction of a
second. It is thought that matter was generated, the structures in the Universe
were formed and cold dark matter froze out during this very early epoch when
the equation of state of the Universe was dominated by the quark-gluon plasma
(QGP). Future Little Bangs may reveal the mechanism of matter generation and
the nature of cold dark matter. Knowledge of the QGP will be an essential
ingredient in quantitative understanding of the very early Universe.


title: Unusual high-redshift radio BAL quasar 1624+3758

abstract:
  We present observations of the most radio-luminous BAL quasar known,
1624+3758, at redshift z = 3.377. The quasar has several unusual properties:
(1) The FeII UV191 1787-A emission line is very prominent. (2) The BAL trough
(BALnicity index 2990 km/s) is detached by 21000 km/s and extends to velocity v
= -29000 km/s. There are additional intrinsic absorbers at -1900 and -2800
km/s. (3) The radio rotation measure of the quasar, 18350 rad/m^2, is the
second-highest known.
  The radio luminosity is P(1.4GHz) = 4.3 x 10^27 W/Hz (H0 = 50 km/s/Mpc, q0 =
0.5), radio loudness R* = 260. The radio source is compact (<~ 2.8 kpc) and the
radio spectrum is GHz-peaked, consistent with it being relatively young. The
width of the CIV emission line, in conjunction with the total optical
luminosity, implies black-hole mass ~ 10^9 M(sun), L/L(Eddington) ~ 2. The high
Eddington ratio, and the radio-loudness, place this quasar in one corner of
Boroson's (2002) 2-component scheme for the classification of AGN, implying a
very high accretion rate, and this may account for some of the unusual observed
properties.
  A complex mini-BAL absorber at v = -3000 km/s is detected in each of CIV, NV
and OVI. The blue and red components of the CIV doublet happen to be unblended,
allowing both the covering factor and optical depth to be determined as a
function of velocity. Variation of covering factor with velocity dominates the
form of the mini-BAL...


title:
Constraints on the distribution of absorption in the X-ray selected AGN
  population found in the 13H XMM-Newton/Chandra deep field

abstract:
  We present an analysis of the X-ray properties of sources detected in the 13H
XMM-Newton deep (200ks) field. In order to constrain the absorbed AGN
population, we use extensive Monte Carlo simulations to directly compare the
X-ray colours of observed sources with those predicted by several model
distributions. We have tested the simplest form of the AGN unified scheme,
whereby the intrinsic XLF of absorbed AGN is set to be the same as that of
their unabsorbed brethren, coupled with various model distributions of
absorption. The best fitting of these models sets the fraction of AGN with
absorbing column NH, proportional to (logNH)^8. We have also tested two
extensions to the unified scheme: an evolving absorption scenario, and a
luminosity dependent model distribution. Both of these provide poorer matches
to the observed X-ray colour distributions than the best fitting simple unified
model. We find that a luminosity dependent density evolution XLF reproduces
poorly the 0.5-2 keV source counts seen in the 13H field. Field to field
variations could be the cause of this disparity. Computing the simulated X-ray
colours with a simple absorbed power-law + reflection spectral model is found
to over-predict, by a factor of two, the fraction of hard sources that are
completely absorbed below 0.5 keV, implying that an additional source of
soft-band flux must be present for a number of the absorbed sources. Finally,
we show that around 40% of the 13H sample are expected to be AGN with NH>10^22
cm^-2.


title:
Hydrodynamical simulations of the decay of high-speed molecular
  turbulence. II. Divergence from isothermality

abstract:
  A roughly constant temperature over a wide range of densities is maintained
in molecular clouds through radiative heating and cooling. An isothermal
equation of state is therefore frequently employed in molecular cloud
simulations. However, the dynamical processes in molecular clouds include shock
waves, expansion waves, cooling induced collapse and baroclinic vorticity, all
incompatible with the assumption of a purely isothermal flow. Here, we
incorporate an energy equation including all the important heating and cooling
rates and a simple chemical network into simulations of three-dimensional,
hydrodynamic, decaying turbulence. This allows us to test the accuracy of the
isothermal assumption by directly comparing a model run with the modified
energy equation to an isothermal model. We compute an extreme case in which the
initial turbulence is sufficiently strong to dissociate much of the gas and
alter the specific heat ratio. The molecules then reform as the turbulence
weakens. We track the true specific heat ratio as well as its effective value.
We analyse power spectra, vorticity and shock structures, and discuss scaling
laws for decaying turbulence. We derive some limitations to the isothermal
approximation for simulations of the interstellar medium using simple
projection techniques. Overall, even given the extreme conditions, we find that
an isothermal flow provides an adequate physical and observational description
of many properties. The main exceptions revealed here concern behaviour
directly related to the high temperature zones behind the shock waves.


title: The mass of the graviton and the cosmological constant puzzle

abstract:
  We propose an interpretation of the cosmological constant puzzle - i.e., the
enormous value of the ratio $\rho_{Pl}/\rho_{vac} \approx 10^{120} $- in terms
of the total number of gravitons in the observable universe based on a recently
discovered relationship between $\Lambda$ and the mass $m_{g}$ of the graviton.


title:
Kinematic Structure of H2 and [Fe II] in the Bipolar Planetary Nebula M
  2-9

abstract:
  We present high-dispersion long-slit IR spectra of the double-shell bipolar
planetary nebula M 2-9 in the emission lines [Fe II] 16435 and H2 v=1--0 S(1)
21218. H2 spectra reveal for the first time the kinematic structure of the
outer shell in M 2-9. Kinematics of the inner shell, traced by [Fe II],
resemble those of optical lines like [N II]. [Fe II] and H2 shells have
expansion speeds roughly proportional to distance from the star (``Hubble''
flows) and share the same dynamical age of 1200--2000 yr, depending on the
distance to M 2-9. Thus, the inner ionized lobes and outer molecular lobes, as
well as the molecular torus and ``outer loops'' measured by other observers,
were all formed around the same time. Consequently, their nested structure
likely arises from an excitation gradient rather than independent ejections. H2
and [Fe II] emission is distributed more uniformly than [N II], and IR lines
are not dominated by the moving ionization pattern like visual-wavelength
lines. We suggest that this is because IR lines of [Fe II] and H2 are excited
by relatively isotropic far-UV radiation (Balmer continuum), whereas optical
lines respond to a directed rotating beam of Lyman continuum. Finally, we
highlight intriguing similarities between M 2-9 and the Homunculus of eta
Carinae, despite the different central engines powering the two nebulae.


title:
On the Meaning and Inapplicability of the Zeldovich Relations of
  Magnetohydrodynamics

abstract:
  Considering a plasma with an initially weak large scale field subject to
nonhelical turbulent stirring, Zeldovich (1957), for two-dimensions, followed
by others for three dimensions, and Zeldovich et al. (1983) have presented
formulae of the form $<b^2>=f(R_M){Bbar}^2$. Such ``Zeldovich relations'' have
sometimes been interpreted to provide steady-state relations between the energy
associated with the fluctuating magnetic field and that associated with a large
scale or mean field multiplied by a function $f$ that depends on spatial
dimension and a magnetic Reynolds number $R_M$. Here we dissect the origin of
these relations and pinpoint pitfalls that show why they are inapplicable to
realistic, dynamical MHD turbulence and that they disagree with many numerical
simulations. For 2-D, we show that when the total magnetic field is determined
by a vector potential, the standard Zeldovich relation applies only
transiently, characterizing a maximum possible value that the field energy can
reach before necessarily decaying. in relation to a seed value $Bbar$. In 3-D,
we show that the standard Zeldovich relations are derived by balancing
subdominant terms. In contrast, balancing the dominant terms shows that the
fluctuating field can grow to a value independent of $R_M$ and the initially
imposed $Bbar$, as seen in numerical simulations. We also emphasize that these
Zeldovich relations of nonhelical turbulence imply nothing about the amount
mean field growth in a helical dynamo. In short, by re-analyzing the origin of
the Zeldovich relations, we highlight that they are inapplicable to realistic
steady-states of large $R_M$ MHD turbulence.


title: Non-linear perturbations in multiple-field inflation

abstract:
  We develop a non-linear framework for describing long-wavelength
perturbations in multiple-field inflation. The basic variables describing
inhomogeneities are defined in a non-perturbative manner, are invariant under
changes of time slicing on large scales and include both matter and metric
perturbations. They are combinations of spatial gradients generalising the
gauge-invariant variables of linear theory. Dynamical equations are derived and
supplemented with stochastic source terms which provide the long-wavelength
initial conditions determined from short-wavelength modes. Solutions can be
readily obtained via numerical simulations or analytic perturbative expansions.
The latter are much simpler than the usual second-order perturbation theory.
Applications are given in a companion paper.


title:
alpha-Enhanced Integrated Lick/IDS Spectral Indices and Milky Way and
  M31 Globular Clusters and Early-type Galaxies

abstract:
  All 25 Lick/IDS spectral indices have been computed for the integrated light
of simple stellar populations over broad ranges of age and metallicity and with
effects from horizontal-branch stars fully implemented. For Balmer indices a
significant response was noted for Hgamma and Hdelta when a-elements are
enhanced, but Hbeta is rather a-insensitive. We also find that our 5 Gyr and 12
Gyr models of Hgamma and Hdelta overlap in the metal-poor regime because of
changing populations of blue horizontal-branch stars. Furthermore, for
populations younger than 1 Gyr, Balmer lines become weaker in the metal-poor
regime because the main-sequence turnoff is hotter than 10,000 K. We present
models at fixed [Fe/H] (rather than fixed heavy element mass fraction Z), and
compare to Milky Way globular clusters that have independently estimated mean
[Fe/H] and [a/Fe]. Comparison of our models with observations of Milky Way and
M31 globular clusters in index-index space are favorable, tracing the
observations at a model age of 12 Gyr without any zero-point shifts that are
needed by some other models. Contrary to the literature values, the Milky Way
globular cluster NGC 6553 appears more metal-rich than NGC 6528 from metal
indices. We present Hdelta and Hgamma Lick/IDS indices for the Lick/IDS sample
of galaxies. We confirm the well-known enhancement of Mg and Na relative to Fe
and Ca among early-type galaxies, and its increase with increasing velocity
dispersion. There are distinct differences between globular clusters and
galaxies in diagrams involving CN1 and CN2, hinting that the globular cluster
environment may be a special one in terms of the amount of N incorporated into
stars. (abridged)


title: Detection of Cosmic Magnification with the Sloan Digital Sky Survey

abstract:
  We present an 8 sigma detection of cosmic magnification measured by the
variation of quasar density due to gravitational lensing by foreground large
scale structure. To make this measurement we used 3800 square degrees of
photometric observations from the Sloan Digital Sky Survey (SDSS) containing
\~200,000 quasars and 13 million galaxies. Our measurement of the galaxy-quasar
cross-correlation function exhibits the amplitude, angular dependence and
change in sign as a function of the slope of the observed quasar number counts
that is expected from magnification bias due to weak gravitational lensing. We
show that observational uncertainties (stellar contamination, Galactic dust
extinction, seeing variations and errors in the photometric redshifts) are well
controlled and do not significantly affect the lensing signal. By weighting the
quasars with the number count slope, we combine the cross-correlation of
quasars for our full magnitude range and detect the lensing signal at >4 sigma
in all five SDSS filters. Our measurements of cosmic magnification probe scales
ranging from 60 kpc/h to 10 Mpc/h and are in good agreement with theoretical
predictions based on the WMAP concordance cosmology. As with galaxy-galaxy
lensing, future measurements of cosmic magnification will provide useful
constraints on the galaxy-mass power spectrum.


title:
Magnetically-Dominated Accretion Flows (MDAFs) and Jet Production in the
  Low/Hard STate

abstract:
  In this paper I propose that the inner part of a black hole accretion inflow
($< 100 r_{g}$) may enter a magnetically-dominated, magnetosphere-like phase in
which the strong, well-ordered fields play a more important role than weak,
turbulent fields. In the low/hard state this flow is interior to the standard
ADAF usually invoked to explain the observed hot, optically thin emission.
Preliminary solutions for these new MDAFs are presented.
  Time-dependent X-ray and radio observations give considerable insight into
these processes, and a new interpretation of the X-ray power spectrum (as
arising from many disk radii) may be in order. While an evaporative ADAF model
explains the noise power above 0.01 Hz, an inner MDAF is needed to explain the
high frequency cutoff near 1 Hz, the presence of a QPO, and the production of a
jet. The MDAF scenario also is consistent with the data-based, phemonenological
models presented at this meeting by several authors.


title:
Identifying Dark Matter Through the Constraints Imposed by Fourteen
  Astronomically Based 'Cosmic Constituents'

abstract:
  Mankind has not yet explained dark matter, the accelerating expansion of the
Universe, the 'knee' and 'ankle' of the cosmic ray energy spectrum graph, the
low star formation rates of low surface brightness (LSB) dwarf galaxies, the
ignition of hydrogen fusion reactions in the first generation stars or the
departing locations of earthbound high-energy cosmic ray protons. A new
research hypothesis has been developed by the author based upon finding
astronomically based 'cosmic constituents' of the Universe that may be created
or influenced by or have a special relationship with possible dark matter
candidates. A list of 14 relevant and plausible 'cosmic constituents' of the
Universe was developed by the author, which was then used to establish a list
of constraints regarding the nature and characteristics of the long-sought dark
matter particles. A dark matter candidate was then found that best conformed to
the 14 constraints established by the 'cosmic constituents.'


title: Search for H3+ in HD141569A

abstract:
  A search for H3+ line emission, reported to have been detected toward the
young star HD 141569A and possibly originating in a clump of planet-forming gas
orbiting the star, has yielded negative results. Observations made at the
United Kingdom Infrared Telescope and at the Subaru Telescope during 2001-2005
covered 11 major transitions of H3+ from 3.42 to 3.99 um. No H3+ emission lines
were detected; one marginal detection at 3.9855 um in June 2002 was not
confirmed in later spectra. The upper limits to the line strengths are
significantly lower than the previously reported detections. Supplemental
slit-scanning spectroscopy using adaptive optics was performed within 0.38 of
HD 141569A to search for extended emission from H3+, but no emission was
detected. We compare our upper limit to the luminosity in H3+ from HD 141569A
with that possible from a gas giant protoplanet and also from a jovian mass
exoplanet in close orbit about its central star.


title: Three-Mirror Anastigmat Telescope with an Unvignetted Flat Focal Plane

abstract:
  A new optical design concept of telescopes to provide an aberration-free,
wide field, unvignetted flat focal plane is described. The system employs three
aspheric mirrors to remove aberrations, and provides a semi-circular field of
view with minimum vignetting. The third mirror reimages the intermediate image
made by the first two-mirror system with a magnification factor on the order of
unity. The present system contrasts with the Korsch system where the
magnification factor of the third mirror is usually much larger than unity. Two
separate optical trains can be deployed to cover the entire circular field, if
necessary.


title: Observations of the BL Lac Object 3C 66A with STACEE

abstract:
  We present the analysis and results of recent high-energy gamma-ray
observations of the BL Lac object 3C 66A conducted with the Solar Tower
Atmospheric Cherenkov Effect Experiment (STACEE). During the 2003-2004
observing season, STACEE extensively observed 3C 66A as part of a
multiwavelength campaign on the source. A total of 33.7 hours of data was taken
on the source, plus an equivalent-duration background observation. After
cleaning the data set a total of 16.3 hours of live time remained, and a net
on-source excess of 1134 events was seen against a background of 231742 events.
At a significance of 2.2 standard deviations this excess is insufficient to
claim a detection of 3C 66A, but is used to establish flux upper limits for the
source.


title:
de Vaucouleurs-Ikeuchi Diagram and Commutation Relations among Phase
  Space Coordinates

abstract:
  We consider the relations between de Vaucouleurs-Ikeuchi diagram and
generalized commutation relations among the coordinates and momenta. All
physical objects in the Universe ranging from elementary particles to super
cluster of galaxies are confined within the Triangle of the de
Vaucouleurs-Ikeuchi diagram on the matter density versus scale length plane.
These three boundaries are characterized by the quantum uncertainty principle,
gravitational event horizon, and cosmological constant. These are specified by
the non-zero commutation relations $[x_\mu,p_\nu], [x_\mu, x_\nu]$ (strictly
$[x_i,t]$) and $[p_\mu,p_\nu]$, respectively. The canonical commutation
relation $[x_i,p_j]$ are slightly modified, which preserves the self
consistency as a whole.


title: Supernovae Shedding Light on Gamma-Ray Bursts

abstract:
  We review the observational status of the Supernova (SN)/Gamma-Ray Burst
(GRB) connection. In section 2 we provide a short summary of the observational
properties of core-collapse SNe. In sections 3-6 we review the circumstantial
evidences and the direct observations that support the existence of a deep
connection between the death of massive stars and GRBs. Present data suggest
that SNe associated with GRBs form a heterogeneous class of objects including
both bright and faint Hypernovae and perhaps also `standard' Ib/c events. In
section 7, we provide an empirical estimate of the rate of Hypernovae, for a
``MilkyWay-like'' galaxy, of about $\sim 2.6\times 10^{-4}$ yr$^{-1}$ that may
imply the ratio GRB/Hypernovae to be in the range $\sim 0.03-0.7$. In the same
framework we find the ratio GRB/SNe-Ibc to be $\sim 0.008\div 0.05$. In section
8 we discuss the possible existence of a lag between the SN explosion and the
associated gamma-ray event. In the few SN/GRB associations so far discovered
the SN explosions and GRB events appear to go off simultaneously. In section 9
we present the conclusions and highlight the open problems that Swift hopefully
will allow us to solve.


title:
Dark energy transition between quintessence and phantom regimes - an
  equation of state analysis

abstract:
  The dark energy transition between quintessence ($w>-1$) and phantom ($w<-1$)
regimes (the crossing of the cosmological constant boundary) is studied using
the dark energy equation of state. Models characterized by this type of
transition are explicitly constructed and their equation of state is found to
be {\em implicitly} defined. The behavior of the more general models with the
implicitly defined equation of state, obtained by the generalization of the
explicitly constructed models, is studied to gain insight into the necessary
conditions for the occurrence of the transition, as well as to investigate the
mechanism behind the transition. It is found that the parameters of the
generalized models need to satisfy special conditions for the transition to
happen and that the mechanism behind the transition is the cancellation of the
contribution of the cosmological constant boundary. The aspects of the behavior
of the generalized models which are not related to the transition are briefly
discussed and the role of the implicitly defined dark energy equation of state
in the description of the dark energy evolution is emphasized.


title:
Cluster number counts dependence on dark energy inhomogeneities and
  coupling to dark matter

abstract:
  Cluster number counts can be used to test dark energy models. We investigate
dark energy candidates which are coupled to dark matter. We analyze the cluster
number counts dependence on the amount of dark matter coupled to dark energy.
Further more, we study how dark energy inhomogeneities affect cluster
abundances. It is shown that increasing the coupling reduces significantly the
cluster number counts, and that dark energy inhomogeneities increases cluster
abundances. Wiggles in cluster number counts are shown to be a specific
signature of coupled dark energy models. Future observations will possibly
detect such oscillations and discriminate among the different dark energy
models.


title: Discovery of VHE Gamma Rays from PKS 2005-489

abstract:
  The high-frequency peaked BL Lac PKS 2005-489 (z=0.071) was observed in 2003
and 2004 with the H.E.S.S. stereoscopic array of imaging atmospheric-Cherenkov
telescopes in Namibia. A signal was detected at the 6.7 sigma level in the 2004
observations (24.2 hrs live time), but not in the 2003 data set (27.3 hrs live
time). PKS 2005-489 is the first blazar independently discovered by H.E.S.S. to
be an emitter of VHE photons, and only the second such blazar in the Southern
Hemisphere. The integral flux above 200 GeV observed in 2004 is (6.9 +/- 1.0
+/- 1.4) x 10$^{-12}$ cm$^{-2}$ s$^{-1}$, corresponding to ~2.5% of the flux
observed from the Crab Nebula. The 99% upper limit on the flux in 2003, I(>200
GeV) < 5.2 x 10$^{-12}$ cm$^{-2}$ s$^{-1}$, is smaller than the flux measured
in 2004, suggesting an increased level of activity in 2004. However, the data
show no evidence for significant variability on any time scale less than a
year. An energy spectrum is measured and is characterized by a very soft power
law (photon index = 4.0 +/- 0.4).


title: Starless Cores

abstract:
  Dense low mass cores in nearby clouds like Taurus and Auriga are some of the
simplest sites currently forming stars like our Sun. Because of their
simplicity and proximity, dense cores offer the clearest view of the different
phases of star formation, in particular the conditions prior to the onset of
gravitational collapse. Thanks to the combined analysis of the emission from
molecular lines and the emission/absorption from dust grains, the last several
years have seen a very rapid progress in our understanding of the structure and
chemical composition of starless cores. Previous contradictions between
molecular tracers are now understood to arise from core chemical
inhomogeneities, which are caused by the selective freeze out of molecules onto
cold dust grains. The analysis of the dust emission and absorption, in
addition, has allowed us to derive accurate density profiles, and has made
finally possible to carry out self consistent modeling of the internal
structure of starless cores. In this paper I briefly review the evolution of
core studies previous to the current golden age, and show how multi-tracer
emission can now be modeled in a systematic manner. Finally I show how we can
start to reconstruct the early history of core formation taking advantage of
the chemical changes in the gas.


title:
Spatially Resolved STIS Spectra of Betelgeuse's Upper Chromosphere and
  Circumstellar Dust Envelope

abstract:
  The Hubble Space Telescope observed red supergiant Betelgeuse with the Space
Telescope Imaging Spectrograph to investigate the outer atmosphere from
spatially resolved spectra. We present a new set of seven high-resolution
near-UV spectra observed with HST-STIS in fall 2002 and spring 2003, by
scanning at chromospheric intensity peak-up position and six off-limb target
positions up to three arcseconds away from the star. A small aperture is used
to study and determine the thermal conditions and flow dynamics in its upper
chromosphere and inner circumstellar dust envelope. We provide the first
evidence for the presence of warm chromospheric plasma at least 3 arcseconds
away from Betelgeuse at ~120 R* (1 R* ~= 700 Rsun) based on detailed
spectroscopic observations of the Mg II h & k emission lines. Many other weak
chromospheric emission lines as Fe II lam2716, C II lam2327, Al II] lam2669,
and Fe I lam2823 are detected out to at least 1 arcsecond in the spatially
resolved STIS observations. The profiles of the Mg II h & k and the Si I
resonance emission lines reveal a strong increase of asymmetry by scanning
off-limb, signaling the outward acceleration of wind expansion in Betelgeuse's
upper chromosphere beyond 200 mas (~8 R*). We discuss detailed radiative
transfer models that fit the STIS observations showing that the local kinetic
gas temperature in the upper chromosphere exceeds 2600 K. Our radiation
transport models for the IR silicate dust emission at 9.8 um in the upper
chromosphere show however that the ambient gas temperature remains below 600 K
to sustain the presence of dust grains. Hence, the STIS spectra of Betelgeuse's
upper chromosphere directly demonstrate that warm chromospheric plasma must
co-exist with cool dusty plasma in its outer atmosphere.


title: Is FIRST J102347.6+003841 Really a Cataclysmic Binary?

abstract:
  The radio source FIRST J102347.6+003841 was presented as the first
radio-selected cataclysmic. In the discovery paper, Bond et al. (2002) show a
spectrum consistent with a magnetic AM Her-type system and a light curve with
rapid, irregular flickering. In contrast, Woudt, Warner, and Pretorius (2004)
found a smoothly-varying light curve with a period near 4.75 h and one minimum
per orbit, indicating a dramatic change. We present time-resolved spectra
showing a superficially normal, mid-G type photosphere, with no detectable
emission lines. The absorption-line radial velocity varies sinusoidally, with
semi-amplitude 268 +- 4 km/s, on the orbital period, which is refined to
0.198094(2) d. At this orbital period the secondary's spectral type is
atypically early, suggesting an unusual evolutionary history. We also obtained
BVI photometry around the orbit. The light curve resembles that given by Woudt
et al., and the color modulation is consistent with a heating effect. A simple
illumination model matches the observations strikingly well with a Roche-lobe
filling secondary near 5650 kelvin being illuminated by a primary giving out
around 2 solar luminosities. The modest amplitude of the observed modulation
constrains the orbital inclination to be less than about 55 deg, unless the
gravity darkening is artificially reduced. The resulting primary star mass is
above the Chandrasekhar limit (assuming conventional gravity darkening). We
examine the possibility that the compact object in this system is not a white
dwarf, in which case this is not actually a cataclysmic variable. On close
examination, FIRST J102347.6+003841 defies easy classification.


title:
Mass-loss and Recent Spectral Changes in the Yellow Hypergiant Rho
  Cassiopeiae

abstract:
  The yellow hypergiant Rho Cassiopeiae (F-G Ia0) has recently become very
active with a tremendous outburst event in the fall of 2000. During the event
the pulsating supergiant dimmed by more than a visual magnitude, while its
effective temperature decreased from 7000 K to below 4000 K over about 200 d,
and we directly observed the largest mass-loss rate of about 5% of the solar
mass in a single stellar outburst so far. Over the past three years since the
eruption we observed a very prominent inverse P Cygni profile in Balmer H
alpha, signaling a strong collapse of the upper atmosphere, also observed
before the 2000 event. Continuous spectroscopic monitoring reveals that the H
alpha line profile has transformed into a P Cygni profile since June 2003,
presently (Sept 2004) signaling supersonic expansion velocities up to ~120 km/s
in the extended upper atmosphere.
  Based on the very recent unique spectral evolution we observed the far-UV
spectrum with the FUSE satellite in July 2004. The FUSE spectrum reveals that
high-temperature plasma emission lines of O VI and C III are absent in the
hypergiant, also observed for the red supergiant Alpha Ori (M2 Iab). On the
other hand, we observe prominent transition region emission lines in the
smaller (less luminous) classical Cepheid variable Beta Dor (F-G Iab-Ia),
indicating that the mean atmospheric extension and surface gravity acceleration
(as compared to effective temperature and atmospheric pulsation) play a major
role for the formation of high-temperature stellar atmospheric plasmas. We
present an overview of the recent spectral variability phases of Rho Cas with
enhanced mass-loss from this enigmatic cool star.


title: Semi-empiric Radiative Transfer Modeling of FUSE Stellar Spectra

abstract:
  We present an overview of radiative transfer modeling efforts to interpret
spectra of a variety of stellar objects observed with FUSE. Detailed radiative
transfer modeling of high ion emission line profiles of C III and O VI observed
in the far-UV spectrum provides a powerful means to probe the thermal and
dynamic properties of high-temperature plasmas in the atmospheres of stars. We
model asymmetric emission lines of C III lam977 observed in spectra of luminous
cool stars such as Alpha Aqr, to infer the wind- and microturbulence velocity
structures of the upper chromosphere. Semi-empiric radiative transfer models
that include transition region temperature conditions, are further developed
based on detailed fits to O VI resonance emission lines in the supergiant Alpha
Aqr, the classical Cepheid variable Beta Dor, and to self-absorbed O VI
emission lines in the cataclysmic variable SW UMa.
  We observe that the C III resonance line profile of Alpha Aqr assumes a
remarkable asymmetric shape, reminiscent of P Cygni type profiles observed in
hot luminous supergiants. The model calculations indicate outflow velocities
above ~140 km/s at kinetic temperatures of 65 kK and higher. Based on detailed
model fits to the narrow red-shifted and self-absorbed O VI emission lines of
SW UMa we compute that the gas- and electron-density exceed the density
conditions of the upper solar transition region by about three orders of
magnitude. We discuss how detailed semi-empiric fits to emission lines observed
with the high spectral resolution of FUSE can provide reliable constraints on
the mass-loss or mass-accretion rates in these objects.


title:
Sensitivity of r-Process Nucleosynthesis to Light-Element Nuclear
  Reactions

abstract:
  We study the efficiency and sensitivity of r-process nucleosynthesis to 18
light-element nuclear reaction rates. We adopt empirical power-law relations to
parameterize the reaction sensitivities. We utilize two different hydrodynamic
models for the neutrino-driven winds in order to study the dependence of our
result on supernova wind models. We also utilize an exponential model to
approximate a wide variety of other plausible conditions for the r-process. We
identify several specific nuclear reactions among light neutron-rich nuclei
that play a critical role in determining the final r-process nucleosynthesis
yields. As an illustration, we examine ``semi-waiting'' points among the carbon
isotopes. We show that not only neutron capture and
  $\beta$-decay, but also $(\alpha, \mathrm{n})$ reactions are important in
determining waiting points along the r-process path. Our numerical results from
this sensitivity analysis serve foremost to clarify which light nuclear
reactions are most influential in determining the final r-process abundances.
We also quantify the effects of present nuclear uncertainties on the final
r-process abundances. This study thus emphasizes and motivates which future
determinations of nuclear reaction rates will most strongly impact our
understanding of r-process nucleosynthesis.


title: Secular Evolution in Mira Variable Pulsations

abstract:
  Stellar evolution theory predicts that asymptotic giant branch stars undergo
a series of short thermal pulses that significantly change their luminosity and
mass on timescales of hundreds to thousands of years. Secular changes in these
stars resulting from thermal pulses can be detected as measurable changes in
period if the star is undergoing Mira pulsations. The American Association of
Variable Star Observers (AAVSO) International Database currently contains
visual data for over 1500 Mira variables. Light curves for these stars span
nearly a century in some cases, making it possible to study the secular
evolution of the pulsation behavior on these timescales. In this paper, we
present the results of our study of period change in 547 Mira variables using
data from the AAVSO. We find non-zero rates of period change, dlnP/dt, at the
2-sigma significance level in 57 of the 547 stars, at the 3-sigma level in 21
stars, and at the level of 6-sigma or greater in eight of the 547. The latter
eight stars have been previously noted in the literature, and our derived rates
of period changes largely agree with published values. The largest and most
statistically significant dlnP/dt are consistent with the rates of period
change expected during thermal pulses on the AGB. A number of other stars
exhibit non-monotonic period changes on decades-long timescales, the cause of
which is not yet known.


title: Multicolor Observations of ASAS 002511+1217.2

abstract:
  We present multicolor CCD photometry of ASAS 002511+1217.2 for first 55 days
of 2004 outburst.


title: The connection between shear and star formation in spiral galaxies

abstract:
  We present a sample of 33 galaxies for which we have calculated (i) the
average rate of shear from publish rotation curves, (ii) the far-infrared
luminosity from IRAS fluxes and (iii) The K-band luminosity from 2MASS. We show
that a correlation exists between the shear rate and the ratio of the
far-infrared to K-band luminosity. This ratio is essentially a measure of the
star formation rate per unit mass, or the specific star formation rate. From
this correlation we show that a critical shear rate exists, above which star
formation would turn off in the disks of spiral galaxies. Using the correlation
between shear rate and spiral arm pitch angle, this shear rate corresponds to
the lowest pitch angles typically measured in near-infrared images of spiral
galaxies.


title: The Kinematic Signature of Face-On Peanut-Shaped Bulges

abstract:
  We present a kinematic diagnostic for peanut-shaped bulges in nearly face-on
galaxies. The face-on view provides a novel perspective on peanuts which would
allow study of their relation to bars and disks in greater detail than hitherto
possible. The diagnostic is based on the fact that peanut shapes are associated
with a flat density distribution in the vertical direction. We show that the
kinematic signature corresponding to such a distribution is a minimum in the
fourth-order Gauss-Hermite moment $s_4$. We demonstrate our method on $N$-body
simulations of varying peanut strength, showing that strong peanuts can be
recognized to inclinations $i \simeq 30\degrees$, regardless of the strength of
the bar. We also consider compound systems in which a bulge is present in the
initial conditions as may happen if bulges form at high redshift through
mergers. We show that in this case, because the vertical structure of the bulge
is not derived from that of the disk, that the signature of a peanut in $s_4$
is weakened. Thus the same kinematic signature of peanuts can be used to
explore bulge formation mechanisms. The observational requirements for
identifying peanuts with this method are challenging, but feasible.


title: Superfluid Spin-down, with Random Unpinning of the Vortices

abstract:
  The so-called ``creeping'' motion of the pinned vortices in a rotating
superfluid involves ``random unpinning'' and ``vortex motion'' as two
physically separate processes. We argue that such a creeping motion of the
vortices need not be (biased) in the direction of an existing radial Magnus
force, nor should a constant microscopic radial velocity be assigned to the
vortex motion, in contradiction with the basic assumptions of the ``vortex
creep'' model. We point out internal inconsistencies in the predictions of this
model which arise due to this unjustified foundation that ignores the role of
the actual torque on the superfluid. The proper spin-down rate of a pinned
superfluid is then calculated and turns out to be much less than that suggested
in the vortex creep model, hence being of even less observational significance
for its possible application in explaining the post-glitch relaxations of the
radio pulsars.


title:
Evidence for the presence of dust in intervening QSO absorbers from the
  Sloan Digital Sky Survey

abstract:
  We find evidence for dust in the intervening QSO absorbers from the spectra
of QSOs in the Sloan Digital Sky Survey Data Release 1. No evidence is found
for the 2175 A feature which is present in the Milky Way dust extinction curve.
The extinction curve resembles the SMC extinction curve. The observed
Delta(g-i) excess for QSOs with strong absorption systems appears to be a
result of the reddening due to dust in the intervening absorbers.


title: A New Model for Iron Emission Lines and Re-Burst in GRB X-Ray Afterglows

abstract:
  Recently iron emission features have been observed in several X-ray
afterglows of GRBs. It is found that the energy obtained from the illuminating
continuum which produces the emission lines is much higher than that of the
main burst.The observation of SN-GRB association indicates a fallback disk
should be formed after the supernovae explosion. The disk is optically thick
and advection-dominated and dense. We suggest that the delayed injection energy
after the initial main burst, much higher than energy of the main burst, causes
the re-burst appearance in GRB afterglow and illuminates the region of the disk
surface with $\tau\approx1$($\tau$ is the optical depth for the Thomson scatter
) and produces the iron emission line whose luminosity can be up to $10^{45}$
erg$s^{-1}$. The duration of the iron line emission can be $10^{4}-10^{5}$ s.
This model can explain the appearance of re-burst and emission lines in GRB
afterglow and disappearance of the iron emission lines, and also can naturally
solve the problem of higher energy of the illuminating continuum than that of
the main burst. This scenario is different from the models put forward to
explain the emission lines before, that can be tested by SWIFT satellite.


title: Extra-planar gas in the spiral galaxy NGC 4559

abstract:
  We present 21-cm line observations of the spiral galaxy NGC 4559, made with
the Westerbork Synthesis Radio Telescope. We have used them to study the HI
distribution and kinematics, the relative amount and distribution of luminous
and dark matter in this galaxy and, in particular, the presence of extra-planar
gas. Our data do reveal the presence of such a component, in the form of a
thick disk, with a mass of 5.9 x 10^8 Mo (one tenth of the total HI mass) and a
mean rotation velocity 25-50 km/s lower than that of the thin disk. The
extra-planar gas may be the result of galactic fountains but accretion from the
IGM cannot be ruled out. With this study we confirm that lagging, thick HI
layers are likely to be common in spiral galaxies.


title:
Binary Quasars in the Sloan Digital Sky Survey: Evidence for Excess
  Clustering on Small Scales

abstract:
  We present a sample of 218 new quasar pairs with proper transverse
separations R_prop < 1 Mpc/h over the redshift range 0.5 < z < 3.0, discovered
from an extensive follow up campaign to find companions around the Sloan
Digital Sky Survey and 2dF Quasar Redshift Survey quasars. This sample includes
26 new binary quasars with separations R_prop < 50 kpc/h (theta < 10
arcseconds), more than doubling the number of such systems known. We define a
statistical sample of binaries selected with homogeneous criteria and compute
its selection function, taking into account sources of incompleteness. The
first measurement of the quasar correlation function on scales 10 kpc/h <
R_prop < 400 kpc/h is presented. For R_prop < 40 kpc/h, we detect an order of
magnitude excess clustering over the expectation from the large scale R_prop >
3 Mpc/h quasar correlation function, extrapolated down as a power law to the
separations probed by our binaries. The excess grows to ~ 30 at R_prop ~ 10
kpc/h, and provides compelling evidence that the quasar autocorrelation
function gets progressively steeper on sub-Mpc scales. This small scale excess
can likely be attributed to dissipative interaction events which trigger quasar
activity in rich environments. Recent small scale measurements of galaxy
clustering and quasar-galaxy clustering are reviewed and discussed in relation
to our measurement of small scale quasar clustering.


title: The Nature of Parallax Microlensing Events Towards the Galactic Bulge

abstract:
  Perhaps as many as 30 parallax microlensing events are known, thanks to the
efforts of the MACHO, OGLE, EROS and MOA experiments monitoring the bulge.
Using Galactic models, we construct mock catalogues of microlensing light
curves towards the bulge, allowing for the uneven sampling and observational
error bars of the OGLE-II experiment. The fraction of parallax events with
delta chi^2 > 50 in the OGLE-II database is around ~1%, though higher fractions
are reported by some other surveys. This is in accord with expectations from
standard Galactic models. The fraction of parallax events depends strongly on
the Einstein crossing time (t_E), being less than 5% at t_E = 50 days but
rising to 50% at t_E > 1 yr. We find that the existence of parallax signatures
is essentially controlled by the acceleration of the observer normalised to the
projected Einstein radius on the observer plane divided by t_E^2. The
properties of the parallax events - time-scales, projected velocities, source
and lens locations - in our mock catalogues are analysed. Typically, ~38% of
parallax events are caused by a disk star microlensing a bulge source, while
\~33% are caused by a disk star microlensing a disk source (of these disk
sources, one sixth are at a distance of 5 kpc or less). There is a significant
shift in mean time-scale from 32 d for all events to ~130d for our parallax
events. There are corresponding shifts for other parameters, such as the
lens-source velocity projected onto the observer plane (~1110 km/s for all
events versus ~80 km/s for parallax events) and the lens distance (6.7 kpc
versus 3.7 kpc). We also assess the performance of parallax mass estimators and
investigate whether our mock catalogue can reproduce events with features
similar to a number of conjectured `black hole' lens candidates.


title:
Analysis of the thin layer of Galactic warm ionized gas in the range 20
  < l < 30 deg, -1.5 < b < +1.5 deg

abstract:
  We present an analysis of the thin layer of Galactic warm ionized gas at an
angular resolution ~ 10'. This is carried out using radio continuum data at 1.4
GHz, 2.7 GHz and 5 GHz in the coordinate region 20 < l < 30 deg, -1.5 < b <
+1.5 deg. For this purpose, we evaluate the zero level of the 2.7 and 5 GHz
surveys using auxiliary data at 2.3 GHz and 408 MHz. The derived zero level
corrections are T_{zero}(2.7 GHz)=0.15 +/- 0.06 K and T_{zero}(5 GHz)=0.1 +/-
0.05 K. We separate the thermal (free-free) and non-thermal (synchrotron)
component by means of a spectral analysis performed adopting an antenna
temperature spectral index -2.1 for the free-free emission, a realistic spatial
distribution of indices for the synchrotron radiation and by fitting,
pixel-by-pixel, the Galactic spectral index. We find that at 5 GHz, for |b| = 0
deg, the fraction of thermal emission reaches a maximum value of 82%, while at
1.4 GHz, the corresponding value is 68%. In addition, for the thermal emission,
the analysis indicates a dominant contribution of the diffuse component
relative to the source component associated with discrete HII regions.


title: Self-interaction spin effects in inspiralling compact binaries

abstract:
  Gravitational radiation drives compact binaries through an inspiral phase
towards a final coalescence. For binaries with\textit{spin, mass quadrupole and
magnetic dipole moments}, various contributions add to this process, which is
characterized by the rate of increase $df/dt$ of the gravitational wave
frequency and the accumulated number $\mathcal{N}$ of gravitational wave
cycles. We present here all contributions to $df/dt$ and $% \mathcal{N}$ up to
the second post-Newtonian order. Among them we give for the first time the
contributions due to the \textit{self-interaction of individual spins}. These
are shown to be commensurable with the proper spin-spin contributions for the
recently discovered J0737-3039 double pulsar, and argued to represent the first
corrections to the radiation reaction in the Lense-Thirring approach.


title: Thermal emission in the prompt phase of gamma-ray bursts

abstract:
  I discuss the interpretation of the prompt phase in gamma-ray bursts as being
dominated by quasi-thermal emission, rather than by synchrotron emission. Such
an interpretation gives a more natural explanation of (i) the observed variety
of spectral shape and spectral evolution, (ii) the observed narrowness of the
distribution of peak energies, as well as (iii) the observed correlations
between peak energy and luminosity. However, the physical setting that could
produce such a scenario is not yet clear.


title:
Subaru HDS Transmission Spectroscopy of the Transiting Extrasolar Planet
  HD 209458b

abstract:
  We have searched for absorption in several common atomic species due to the
atmosphere or exosphere of the transiting extrasolar planet HD 209458b, using
high precision optical spectra obtained with the Subaru High Dispersion
Spectrograph (HDS). Previously we reported an upper limit on H alpha absorption
of 0.1% (3 sigma) within a 5.1\AA band. Using the same procedure, we now report
upper limits on absorption due to the optical transitions of Na D, Li, H alpha,
H beta, H gamma, Fe, and Ca. The 3 sigma upper limit for each transition is
approximately 1% within a 0.3\AA band (the core of the line), and a few tenths
of a per cent within a 2\AA band (the full line width). The wide-band results
are close to the expected limit due to photon-counting (Poisson) statistics,
although in the narrow-band case we have encountered unexplained systematic
errors at a few times the Poisson level. These results are consistent with all
previously reported detections and upper limits, but are significantly more
sensitive.


title:
Water masers in the massive protostar IRAS 20126+4104: ejection and
  deceleration

abstract:
  We report on the first multi-epoch, phase referenced VLBI observations of the
water maser emission in a high-mass protostar associated with a disk-jet
system. The source under study, IRAS 20126+4104, has been extensively
investigated in a large variety of tracers, including water maser VLBA data
acquired by us three years before the present observations. The new findings
fully confirm the interpretation proposed in our previous study, namely that
the maser spots are expanding from a common origin coincident with the
protostar. We also demonstrate that the observed 3-D velocities of the maser
spots can be fitted with a model assuming that the spots are moving along the
surface of a conical jet, with speed increasing for increasing distance from
the cone vertex. We also present the results of single-dish monitoring of the
water maser spectra in IRAS 20126+4104. These reveal that the peak velocity of
some maser lines decreases linearly with time. We speculate that such a
deceleration could be due to braking of the shocks from which the maser
emission originates, due to mass loading at the shock front or dissipation of
the shock energy.


title: The conspicuous gamma-ray burst of 30 May 1996

abstract:
  The spectra of the majority of bursts exhibit a low-energy power law index,
alpha, that is either a constant or becomes softer with time. However, in the
burst of 30 May 1996 alpha becomes harder. Here we show that this behavior can
be explained by a hybrid model consisting of a thermal and a non-thermal
component. In this burst the power-law index of the non-thermal component
changes drastically from s ~ -1.5 to s ~ -0.67 at approximately 5 seconds after
the trigger, thereby revealing, at low energies, the thermal component with its
hard Rayleigh-Jeans tail. This leads to the large alpha-values that are found
if the Band function is fitted to the spectra. We suggest that the change in s
could be due to a transition from fast to slow cooling of the electrons
emitting in the BATSE range. This could be due to the fact that the magnetic
field strength becomes weaker.


title:
Formation of molecular hydrogen on analogues of interstellar dust
  grains: experiments and modelling

abstract:
  Molecular hydrogen has an important role in the early stages of star
formation as well as in the production of many other molecules that have been
detected in the interstellar medium. In this review we show that it is now
possible to study the formation of molecular hydrogen in simulated
astrophysical environments. Since the formation of molecular hydrogen is
believed to take place on dust grains, we show that surface science techniques
such as thermal desorption and time-of-flight can be used to measure the
recombination efficiency, the kinetics of reaction and the dynamics of
desorption. The analysis of the experimental results using rate equations gives
useful insight on the mechanisms of reaction and yields values of parameters
that are used in theoretical models of interstellar cloud chemistry.


title: Evolution of Low-Mass Population III Stars

abstract:
  We present the evolutionary models of metal-free stars in the mass range from
0.8 to 1.2 Msun with up-to-date input physics. The evolution is followed to the
onset of hydrogen mixing into a convection, driven by the helium flash at red
giant or asymptotic giant branch phase.
  The models of mass M >= 0.9 Msun undergo the central hydrogen flash,
triggered by the carbon production due to the 3-alpha reactions.
  We find that the border of the off-center and central ignition of helium core
flash falls between 1.1 and 1.2 Msun; the models of mass M <= 1.1 Msun
experience the hydrogen mixing at the tip of red giant branch while the models
of M = 1.2 Msun during the helium shell flashes on the asymptotic giant branch.
  The equation of state for the Coulomb liquid region, where electron
conduction and radiation compete, is shown to be important since it affects the
thermal state in the helium core and influences the red giant branch evolution.
  It is also found that the non-resonant term of 3-alpha reactios plays an
important role, although it has negligible effect in the evolution of stars of
younger populations.
  We compare our models with the computations by several other sets of authors,
to confirm the good agreement except for one study which finds the helium
ignition much closer to the center with consequences important for subsequent
evolution.


title: The ALHAMBRA Survey: For a systematic Study of Cosmic Evolution

abstract:
  ALHAMBRA is a project to gather data to sample a fraction of the Universe
with enough precision to follow the evolution of its content and properties
with z, a kind of Cosmic Tomography. It is defined as a 4 square degrees
photometric survey with 20 contiguous, equal width, medium band filters
covering from 3500 to 9700 A, plus the JHKs NIR bands. It was optimized to get
(for a fixed observing time) the maximum number of objects with accurate
classification and redshift and to be sensitive to relatively faint emission
features. The observations will be carried out with the 3.5m telescope in Calar
Alto (Spain). We intend to reach the limit AB=25 in all the optical filters
from the bluest to 8300 A, and from 24.7 to 23.4 for the remainder. The
expected limit in the NIR is fixed at Ks=20, H=21, J=22. The homogeneous and
contiguous spectral coverage will result in several hundred thousand objects
with accurate SED identification and z-values. The accuracy of the survey will
allow to make detailed studies, including galactic, without the need for any
further follow-up. Indeed, it will provide exciting targets for large
telescopes, the GTC in particular.


title: Core Collapse via Coarse Dynamic Renormalization

abstract:
  In the context of the recently developed "equation-free" approach to
computer-assisted analysis of complex systems, we extract the self-similar
solution describing core collapse of a stellar system from numerical
experiments. The technique allows us to side-step the core "bounce" that occurs
in direct N-body simulations due to the small-N correlations that develop in
the late stages of collapse, and hence to follow the evolution well into the
self-similar regime.


title:
The origin of HE0107-5240 and the production of O and Na in extremely
  metal-poor stars

abstract:
  We elaborate the binary scenario for the origin of HE0107-5240, the most
metal-poor star yet observed ([Fe/H] = -5.3), using current knowledge of the
evolution of extremely metal-poor stars. From the observed C/N value, we
estimate the binary separation and period. Nucleosynthesis in a helium
convective zone into which hydrogen has been injected allows us to discuss the
origin of surface O and Na as well as the abundance distribution of s-process
elements. We can explain the observed abundances of 12C, 13C, N, O, and Na and
predict future observations to validate the Pop III nature of HE0107-5240.


title:
Infrared spectroscopy of Nova Cassiopeiae 1993 (V705 Cas). IV. A closer
  look at the dust

abstract:
  Nova Cassiopeiae 1993 (V705 Cas) was an archetypical dust-forming nova. It
displayed a deep minimum in the visual light curve, and spectroscopic evidence
for carbon, hydrocarbon and silicate dust. We report the results of fitting the
infrared spectral energy distribution with the DUSTY code, which we use to
determine the properties and geometry of the emitting dust. The emission is
well described as originating in a thin shell whose dust has a carbon:silicate
ratio of ~2:1 by number (1.26:1 by mass) and a relatively flat size
distribution. The 9.7micron and 18micron silicate features are consistent with
freshly-condensed dust and, while the lower limit to the grain size
distribution is not well constrained, the largest grains have dimensions
\~0.06micron; unless the grains in V705 Cas were anomalously small, the sizes
of grains produced in nova eruptions may previously have been overestimated in
novae with optically thick dust shells. Laboratory work by Grishko & Duley may
provide clues to the apparently unique nature of nova UIR features.


title:
Structural Parameters of Dwarf Galaxies in the Coma Cluster: On the
  Origin of dS0 Galaxies

abstract:
  In this paper we analyze the structural parameters of the dwarf galaxies in
the Coma cluster with $-18 \le M_{B} \le -16$ and classify them in two types:
those with surface brightness profiles well fitted by a single Sersic law were
called dwarf ellipticals (dEs), and those fitted with Sersic-plus-exponential
profiles were classified as dwarf lenticulars (dS0s). The comparison of the
structural parameters of the dwarf galaxies in the Coma and Virgo clusters
shows that they are analogous. Photometrically, the dE and dS0 galaxies in Coma
are equivalent, having similar colors and global scales. However, the scale of
the innermost parts (bulges) of dS0 galaxies is similar to the bulges of
late-type spiral galaxies. In contrast, dEs have larger scales than the bulges
of bright galaxies. This may indicate that dS0 and dE galaxies have different
origins. While dE galaxies can come from dwarf irregulars (dIs) or from similar
processes as bright Es, the origin of dS0 galaxies can be harassed bright
late-type spiral galaxies.


title:
The Stochastic Effect of Ly-alpha absorbers on Broadband Luminosities of
  Galaxies

abstract:
  We investigate the variations of broadband luminosities of low and
intermediate redshift galaxies due to the stochastic nature of the neutral
hydrogen present in form of Ly-alpha absorbers in the intergalactic medium.
This effect is caused by variations in the distribution and properties
(redshift, column density, Doppler parameter) of the absorbers along different
lines-of-sight out to a given redshift. Using a set of observationally
constrained redshift-, column density- and Doppler parameter distributions we
perform Monte Carlo simulations for a large number of lines-of-sight towards
galaxies at a given redshift z and calculate attenuated FUV/NUV magnitudes and
corresponding 1-, 2- and 3-sigma variations. We predict significant variations
in luminosity ranging from -0.22 to +0.48 magnitudes at the 1-sigma level for
galaxies at z=1.5 in GALEX data.


title:
Precision measurement of cosmic magnification from 21 cm emitting
  galaxies

abstract:
  We show how precision lensing measurements can be obtained through the
lensing magnification effect in high redshift 21cm emission from galaxies.
Normally, cosmic magnification measurements have been seriously complicated by
galaxy clustering. With precise redshifts obtained from 21cm emission line
wavelength, one can correlate galaxies at different source planes, or exclude
close pairs to eliminate such contaminations.
  We provide forecasts for future surveys, specifically the SKA and CLAR. SKA
can achieve percent precision on the dark matter power spectrum and the galaxy
dark matter cross correlation power spectrum, while CLAR can measure an
accurate cross correlation power spectrum. The neutral hydrogen fraction was
most likely significantly higher at high redshifts, which improves the number
of observed galaxies significantly, such that also CLAR can measure the dark
matter lensing power spectrum. SKA can also allow precise measurement of
lensing bispectrum.


title: Relativistic jet motion in the core of the radio-loud quasar J1101+7225

abstract:
  Multi-epoch GHz Very Long Baseline Interferometry (VLBI) data of the
radio-loud quasar J1101+7225 were analyzed to estimate the proper motion of
extended optically thin jet components. Two components separated from the core
could be mapped at 1.66 GHz, which is consistent with earlier observations. In
one case we found evidence of high apparent superluminal motion (beta_app=
22.5+/-4) at large (deprojected) distances to the core (22 mas ~ 4 kpc at z=
1.46). Typically in other quasars such high separation velocities are only
found much closer to the core component. Furthermore the Doppler factor, the
magnetic field strength, and the angular size of the optically thick core were
derived using published X-ray data. Analysis of 5 GHz VLBI data reveals the
existence of further jet components within the central 5 mas. Additionally the
data published so far on the GHz-spectrum were discussed at all angular
resolutions. J1101+7225 turns out to be a standard quasar for studying
different aspects of radio jet kinematics out to kpc-scales.


title: Limits on stochastic magnetic fields: A defense of our paper [1]

abstract:
  In their recent paper ``Faraday rotation of the cosmic microwave background
polarization by a stochastic magnetic field'', Kosowsky et al. Phys.Rev. D71,
043006 (2005) have commented about our paper [C.Caprini and R.Durrer, Phys.
Rev. D65, 023517 (2002)], in which we derived very strong limits on the
amplitude of a primordial magnetic field from gravitational wave production.
They argue that our limits are erroneous. In this short comment we defend our
result.


title:
On the Parameters determining the Neutrino Flux from observed Active
  Galactic Nuclei

abstract:
  Extrapolating from a sample of 39 AGNs, we examine the impact on the total
number of high energy muon-neutrino induced events (PeV-EeV) expected in
IceCube (a 1Km^3 ``neutrino telescope''), due to variations in different
parameters involved in the neutrino flux, such as the emission region geometry,
the estimation models and distributions of the Doppler factor and the
variability time. This work has been done taking into account different limits
of the extragalactic neutrino flux.
  Among our conclusions, we find, in the case of the largest variability time,
that the cylindrical geometry hypothesis for the emission region, produce a
separation of 3 sigma in the total number of events relative to the spherical
hypothesis. In addition, for similar choices of the burst time, spherical
geometry and for the upper neutrino flux bound, we obtain a separation of 2.5
sigma in the total number of events, for some of the Doppler factor
estimations. These differences are undistinguishable for other input values.