title:
Abundance Anomalies and Rotational Evolution of Low Mass Red Giants: A
  Maximal Mixing Approach

abstract:
  (ABRIDGED) We use a fully self-consistent evolutionary code to follow the
rotational evolution of red giants, making a comprehensive attempt to assess
the role of rotationally induced mixing in the development of abundance
anomalies in giants with a range of masses and metallicities in stellar
clusters and the field. Unlike most previous work, we do not focus on the
determination of combinations of mixing rate and depth that reproduce the data
on a particular stellar type. Instead, we concentrate on the more fundamental
problem of the simultaneous reproduction of the CNO surface patterns in both
Population I and Population II giants using the same physics and models. A
general result of all our models is that rotational mixing, although present in
small amounts, is inefficient on the lower RGB independently of any inhibiting
effect of composition barriers. Models with differentially rotating envelopes
are able to reproduce the carbon isotope data on M67 giants with initial
rotation rates adequate to their progenitors, but fail to do so for open
clusters of larger turnoff mass as well as for metal-poor giants in the field
and globular clusters. Possible solutions are discussed. Our favored scenario
is one in which the overall strength of canonical extra mixing has been
underestimated by existent derivations, but which additionally needs to be
coupled with a much lower efficiency for rotational mixing among the rapidly
rotating open cluster giants than in the slowly rotating ones in the field and
globular clusters. We hypothesize that this last requirement is provided by the
interaction between convection and rotation in the envelopes of giants, in the
sense that rapidly rotating stars would develop much shallower angular velocity
profiles in their envelopes than do slowly rotating stars.


title:
A deep, narrow J-band search for proto-galactic Lyman Alpha emission at
  redshifts z~9

abstract:
  We present a deep, narrow J-band search for proto--galactic Lyman Alpha
emission at redshifts z~9. We combine an exceptionally deep image of the Hubble
Deep Field South, obtained using a narrow band filter centred on the wavelength
1.187 microns using the VLT/ISAAC facility, with existing deep, broad band
images covering optical to near infrared wavelengths. We search for z~9 Lyman
Alpha emitting galaxies displaying a significant narrow band excess relative to
the Js-band that are undetected at optical wavelengths. We detect no sources
consistent with this criterion to the 90% point source flux limit of the NB
image, F_{NB} = 3.28 x 10^{-18} ergs/s/cm2. The survey selection function
indicates that we have sampled a volume of approximately 340 h^{-3} Mpc^3 to a
Lyman Alpha emission luminosity of 10^{43} h^{-2} ergs/s. We conclude by
considering the potential implications for the physics of the high--redshift
universe.


title: The Neon Abundance of Galactic Wolf-Rayet Stars

abstract:
  The fast, dense winds which characterize Wolf-Rayet (WR) stars obscure
  their underlying cores, and complicate the verification of evolving
  core and nucleosynthesis models. Core evolution can be probed by
  measuring abundances of wind-borne nuclear processed elements,
  partially overcoming this limitation. Using ground-based mid-infrared
  spectroscopy and the 12.81um [NeII] emission line measured in
  four Galactic WR stars, we estimate neon abundances and compare to
  long-standing predictions from evolved-core models. For the WC star
  WR121, this abundance is found to be >~11x the cosmic
  value, in good agreement with predictions. For the three less-evolved
  WN stars, little neon enhancement above cosmic values is measured, as
  expected. We discuss the impact of clumping in WR winds on this
  measurement, and the promise of using metal abundance ratios to
  eliminate sensitivity to wind density and ionization structure.


title:
Optimization of Starburst99 for Intermediate-Age and Old Stellar
  Populations

abstract:
  We have incorporated the latest release of the Padova models into the
evolutionary synthesis code Starburst99. The Padova tracks were extended to
include the full asymptotic giant branch (AGB) evolution until the final
thermal pulse over the mass range 0.9 to 5 solar mass. With this addition,
Starburst99 accounts for all stellar phases that contribute to the integrated
light of a stellar population with arbitrary age from the extreme ultraviolet
to the near-infrared. AGB stars are important for ages between 0.1 and 2 Gyr,
with their contribution increasing at longer wavelengths. We investigate
similarities and differences between the model predictions by the Geneva and
the Padova tracks. The differences are particularly pronounced at ages > 1 Gyr,
when incompleteness sets in for the Geneva models. We also perform detailed
comparisons with the predictions of other major synthesis codes and found
excellent agreement. Our synthesized optical colors are compared to
observations of old, intermediate-age, and young populations. Excellent
agreement is found for the old globular cluster system of NGC 5128 and for old
and intermediate-age clusters in NGC 4038/39. In contrast, the models fail for
red supergiant dominated populations with sub-solar abundances. This failure
can be traced back to incorrect red supergiant parameters in the stellar
evolutionary tracks. Our models and the synthesis code are publicly available
as version 5.0 of Starburst99 at http://www.stsci.edu/science/starburst99/.


title:
An Overabundance of Transient X-ray Binaries within 1 pc of the Galactic
  Center

abstract:
  During five years of Chandra observations, we have identified seven X-ray
transients located within 23 pc of Sgr A*. These sources each vary in
luminosity by more than a factor of 10, and have peak X-ray luminosities
greater than 5e33 erg/s, which strongly suggests that they are accreting black
holes or neutron stars. The peak luminosities of the transients are
intermediate between those typically considered outburst and quiescence for
X-ray binaries. Remarkably four of these transients lie within only 1 pc of Sgr
A*. This implies that, compared to the numbers of similar systems located
between 1 and 23 pc, transients are over-abundant by a factor of 20 per unit
stellar mass within 1 pc of Sgr A*. It is likely that the excess transient
X-ray sources are low-mass X-ray binaries that were produced, as in the cores
of globular clusters, by three-body interactions between binary star systems
and either black holes or neutron stars that have been concentrated in the
central parsec through dynamical friction. Alternatively, they could be
high-mass X-ray binaries that formed among the young stars that are present in
the central parsec.


title:
Scintillation-induced Variability in Radio Absorption Spectra against
  Extragalactic Sources

abstract:
  Spectral features absorbed against some radio quasars exhibit ~50mJy
variations, with the lines varying both relative to the continuum and, when
several lines are present, even relative to one another. We point out that such
variability can be expected as a consequence of refractive scintillation caused
by the interstellar medium of our Galaxy. Scintillation can cause independent
variations between closely-spaced spectral lines, and can even alter the line
profile. The background source need not be compact to exhibit spectral
variability. The variability can be used to infer the parsec to sub-parsec
scale structure of the intervening absorbing material. We discuss the
importance of scintillation relative to other possible origins of spectral
variability. The present theory is applied to account for the variations
observed in the HI-absorbed quasar PKS 1127-145.


title:
Stellar Bowshocks in the Northern Arm of the Galactic Center: More
  Members and Kinematics of the Massive Star Population

abstract:
  We present new 2.2 micron diffraction-limited images from the W. M. Keck 10 m
and Gemini 8 m telescopes of the cool Galactic Center sources, IRS 1W, 5, 8,
10W, and 21 along with new proper motions for IRS 1W, 10W and 21. These
observations were carried out to test the bowshock hypothesis presented by
Tanner et al. as an alternative to a very recent (10^4 yr) epoch of star
formation within the tidal stream of gas and dust known as the Northern Arm.
Resolved asymmetric structure is detected in all the sources, with bowshock
morphologies associated with IRS 1W, 5, 8 and 10W. For IRS 1W and 10W, there is
an agreement between the position angle of the asymmetry and that of the
relative velocity vector of the near-infrared source with respect to the
Northern Arm gas strengthening the bowshock hypothesis. We therefore conclude
that the observed morphology is indeed a bowshock generated by sources plowing
through the Northern Arm. Furthermore, the large extent of the resolved
structures (310-1340 AU) along with their luminosities (~10^4-5 Lsun) suggests
that their central sources are Wolf-Rayet stars, comparable to the broad He
emission-line stars, which have strong winds on the order of 1000 km/s. The
bowshock morphology, along with the proper motion measurements, provide
three-dimensional orbital solutions for this enigmatic class of objects; IRS 1W
and 10W have orbital planes that are consistent with that of the putative
clockwise plane which has been proposed as a solution for the He I
emission-line stars. While these observations eliminate the need to invoke star
formation within the Northern Arm, they increase by 14% the total known
population of massive, young stars with strong winds, whose origin remains
unexplained in the context of the nearby supermassive black hole.


title:
Lorentz Invariance Violation and the Spectrum and Source Power of
  Ultrahigh Energy Cosmic Rays

abstract:
  Owing to their isotropy, it is generally believed that ultrahigh energy
cosmic rays (UHECRs) are extragalactic in origin. It is then expected that
interactions of these cosmic rays with photons of the cosmic background
radiation (CBR) should produce a drastic reduction in their flux above and
energy of about $5 \times 10^{19}$ eV (50 EeV), the so-called ``GZK effect''.
At present, the existence of this effect is uncertain owing to conflicting
observational data and small number statistics. We show here that a small
amount of Lorentz invariance violation (LIV), which could turn off photomeson
interactions of UHECRs with the CBR, could explain the UHECR spectrum as
measured by {\it AGASA} which shows an excess of UHECRs at energies above 100
EeV. If new results from the {\it Auger} array agree with the {\it AGASA}
spectrum, this may be interpreted as evidence for a small amount of LIV. If, on
the other hand, the new results are consistent with the {\it HiRes} results
favoring a GZK effect, this would place severe constraints on LIV and, by
implication, on some Planck scale quantum gravity models. We also discuss the
power requirements needed to explain the UHECR spectrum for a range of
assumptions, including source evolution and LIV and show that in all cases our
results disfavor a $\gamma$-ray burst origin for the UHECRs.


title: Is the Radio Core of BL Lac Precessing?

abstract:
  Stirling et al. (2003) reported the discovery of a 2.3 year periodic
variation in the structural position angle of the parsec-scale radio core of
the blazar BL Lac. We searched for independent confirmation of this periodic
behavior using 43 GHz images of the radio core during ten epochs overlapping
those of Stirling et al. Our maps are consistent with several periodicities,
including one near the period reported by Stirling et al. By comparing our
position angle measurements with those of Stirling et al., we find strong
consistent evidence for position angle variations of the inner core during the
observed epochs. However, the claim for periodic variation is not convincing,
especially when the most recent epochs (2000.60 - 2003.78) are included. A
definitive resolution will require continued monitoring of the core structure
over several periods.


title: Using Weak Lensing to find Halo Masses

abstract:
  Since the strength of weak gravitational lensing is proportional to the mass
along the line of sight, it might be possible to use lensing data to find the
masses of individual dark matter clusters. Unfortunately, the effect on the
lensing field of other matter along the line of sight is substantial. We
investigate to what extent we can correct for these projection effects if we
have additional information about the most massive halos along the line of
sight from deep optical data. We conclude that unless we know the masses and
positions of halos down to a very low mass, we can only correct for a small
part of the line-of-sight projection, which makes it very hard to get accurate
mass estimates of individual halos from lensing data.


title:
The History of the Mysterious Eclipses of KH 15D II. Asiago, Kiso, Kitt
  Peak, Mt. Wilson, Palomar, Tautenburg and Rozhen Observatories, 1954-97

abstract:
  The unusual pre-main-sequence binary star named KH 15D undergoes remarkably
deep and long-lasting periodic eclipses. Some clues about the reason for these
eclipses have come from the observed evolution of the system's light curve over
the last century. Here we present UBVRI photometry of KH 15D based on
photographic plates from various observatories, ranging in time from 1954 to
1997. The system has been variable at the ~1 mag level since at least 1965.
There is no evidence for color variations, with a typical limit of Delta(B-V) <
0.2 mag. We confirm some previously published results that were based on a
smaller sample of plates: from approximately 1965 to 1990, the total flux was
modulated with the 48-day orbital period of the binary, but the maximum flux
was larger, the fractional variations were smaller, and the phase of minimum
flux was shifted by almost a half-cycle relative to the modern light curve. All
these results are consistent with the recently proposed theory that KH 15D is
being occulted by an inclined, precessing, circumbinary ring.


title: Chandra Localizations of LMXBs: IR Counterparts and their Properties

abstract:
  We present new Chandra observations of the low mass X-ray binaries (LMXBs)
X1624-490, X1702-429, and X1715-321 and the search for their Infrared (IR)
counterparts. We also report on early results from our dedicated IR survey of
LMXBs. The goal of this program is to investigate whether IR counterparts can
be identified through unique IR colors and to trace the origin of the IR
emission in these systems.


title: A possible 3:2 orbital epicyclic resonance in QPOs frequencies of Sgr A*

abstract:
  A recent measurement of double peak QPOs frequencies in Sgr A* is consistent
with the 3:2 ratio. The same ratio is firmly established by previous
observations in all double peak kHz QPOs in microquasars and theoretically
explained by orbital epicyclic resonances excited in nearly Keplerian accretion
flow in black hole's strong gravity. If confirmed, the 3:2 ratio of double peak
QPOs in Sgr A$^*$ will be of a fundamental importance for the black hole
accretion theory, by providing another clear argument that the accretion disk
oscillations are indeed governed by non-linear, strong-gravity physics.


title: The Far Ultraviolet Spectrum of Z Cam in Quiescence

abstract:
  We have obtained Far Ultraviolet Spectroscopic Explorer (905-1187 Angstrom)
spectra of the non-magnetic cataclysmic variable Z Cam during a period of
quiescence. The spectrum resembles that of a hot (57,000 K) metal-enriched
white dwarf. A high effective temperature is consistent with the expectation
that dwarf nova systems that show standstills, as Z Cam does, have higher than
normal time-averaged mass accretion rates. It is also consistent with current
estimates for the mass and distance to Z Cam. A white dwarf model in which 29%
of the surface has a temperature of 72,000 K and the rest of the surface is at
26,000 K also reproduces the spectral shape and the continuum flux level at the
nominal distance and WD mass, and is a somewhat better statistical fit to the
data. A second component could be due to a rotating accretion belt, a remnant
of an outburst that ended eleven days prior to the FUSE observation, or ongoing
accretion. We favor the uniform temperature model for Z Cam, largely because
the data do not require anything more complicated. We have compared the
quiescent spectrum with an archival spectrum of Z Cam in standstill, obtained
with ORFEUS. The standstill spectrum is described well by a disk accreting at a
rate of 7(-2,+4) 10**16 gm/s, where the errors depend on the assumed
inclination.
  The quiescent spectra cover a full orbital period and are time-resolved to
500 s. No variability was observed in the continuum during the observation, but
the depth of many of the absorption lines increased between orbital phases 0.65
and 0.81. We attribute this effect to absorption by material associated with
the accretion stream, which is easier to understand if the inclination is near
the maximum allowed value of 68 degrees.


title: Solar Abundance of Elements from Neutron-Capture Cross Sections

abstract:
  Excess lightweight products of slow neutron capture in the photosphere, over
the mass range of 25 to 207 amu, confirm the solar mass separation recorded by
excess lightweight isotopes in the solar wind, over the mass range of 3 to 136
amu [Solar Abundance of the Elements, Meteoritics, volume 18, 1983, pages 209
to 222]. Both measurements show that major elements inside the Sun are Fe, O,
Ni, Si and S, like those in rocky planets.


title: Extreme Test of Quantum Theory with Black Holes

abstract:
  We propose an extreme test of quantum theory using astrophysical black holes
and entangled photons from atomic cascades. The identification of a cascade
emission close to a black-hole event horizon would allow us to observe photons
entangled with partners that have fallen behind the horizon. The experiment
involves testing the characteristic cos^2(theta) modulation of photon
transmission through a pair of polarisers at relative angle theta (Malus' law).
For single photons, Malus' law is a remarkable feature of quantum theory: it is
equivalent to expectation additivity for incompatible observables, and is
generically violated for hidden-variables theories with nonstandard probability
distributions. An experiment with entangled states straddling an event horizon
is motivated by the Hawking information loss puzzle, as well as on general
grounds. In principle, one could test the currently observed X-ray photons in
iron lines from black-hole accretion discs. However, only a small fraction
(~0.6%) have cascade partners, and current X-ray polarimetry does not permit
successive measurements on a single X-ray photon. A realisable experiment
requires the identification of an appropriate cascade in a more convenient
frequency band.


title: Further Criteria for the Existence of Steady Line-Driven Winds

abstract:
  In Paper I, we showed that steady line-driven disk wind solutions can exist
by using "simple" models that mimic the disk environment. Here I extend the
concepts introduced in Paper I and discuss many details of the analysis of the
steady/unsteady nature of 1D line-driven winds. This work confirms the results
and conclusions of Paper I, and is thus consistent with the steady nature of
the 1D streamline line-driven disk wind models of Murray and collaborators and
the 2.5D line-driven disk wind models of Pereyra and collaborators. When
including gas pressures effects, as is routinely done in time-dependent
numerical models, I find that the spatial dependence of the nozzle function
continues to play a key role in determining the steady/unsteady nature of
supersonic line-driven wind solutions. I show here that the
existence/nonexistence of local wind solutions can be proved through the nozzle
function without integrating the equation of motion. This work sets a detailed
framework with which we will analyze, in a following paper, more realistic
models than the "simple" models of Paper I.


title:
The Optical Gravitational Lensing Experiment. Ellipsoidal Variability of
  Red Giants in the Large Magellanic Cloud

abstract:
  We used the OGLE-II and OGLE-III photometry of red giants in the Large
Magellanic Cloud to select and study objects revealing ellipsoidal variability.
We detected 1546 candidates for long period ellipsoidal variables and 121
eclipsing binary systems with clear ellipsoidal modulation. The ellipsoidal red
giants follow a period-luminosity (PL) relationship (sequence E), and the
scatter of the relation is correlated with the amplitude of variability: the
larger the amplitude, the smaller the scatter.
  We note that some of the ellipsoidal candidates exhibit simultaneously OGLE
Small Amplitude Red Giants pulsations. Thus, in some cases the Long Secondary
Period (LSP) phenomenon can be explained by the ellipsoidal modulation.
  We also select about 1600 red giants with distinct LSP, which are not
ellipsoidal variables. We discover that besides the sequence D in the PL
diagram known before, the LSP giants form additional less numerous sequence for
longer periods. We notice that the PL sequence of the ellipsoidal candidates is
a direct continuation of the LSP sequence toward fainter stars, what might
suggest that the LSP phenomenon is related to binarity but there are strong
arguments against such a possibility.
  About 10% of the presented light curves reveal clear deformation by the
eccentricity of the system orbits. The largest estimated eccentricity in our
sample is about 0.4.
  All presented data, including individual BVI observations and finding charts
are available from the OGLE Internet archive.


title: Dust Sensitivity of Absorption-Line Indices

abstract:
  We investigate the effects of dust extinction on integrated absorption-line
indices that are widely used to derive constraints on the ages and
metallicities of composite stellar systems. Typically, absorption-line studies
have been performed on globular clusters or elliptical galaxies, which are
mostly dust-free systems. However, many recent studies of integrated stellar
populations have focused on spiral galaxies which may contain significant
amounts of dust. It is almost universally assumed that the effects of dust
extinction on absorption-line measurements are entirely negligible given the
narrow baseline of the spectral features, but no rigorous study has yet been
performed to verify this conjecture. In this analysis, we explore the
sensitivity of the standard set of Lick absorption-line indices, the
higher-order Balmer line indices, the 4000 A break, the near-IR calcium triplet
indices, and the Rose indices to dust absorption according to population
synthesis models that incorporate a multi-component model for the line and
continuum attenuation due to dust. The latter takes into account the finite
lifetime of stellar birth clouds. While dust does not greatly affect the
line-index measurements for single stellar populations, its effect can be
significant for the 4000 A break or when there is a significant amount of
current star formation.


title: The radio counter-jet of the QSO 3C~48

abstract:
  We present multi--frequency radio observational results of the quasar 3C~48.
The observations were carried out with the Very Large Array (VLA) at five
frequencies of 0.33, 1.5, 4.8, 8.4, and 22.5 GHz, and with the Multi--Element
Radio Linked Interferometer Network (MERLIN) at the two frequencies of 1.6 and
5 GHz. The source shows a one--sided jet to the north within 1\arcsec, which
then extends to the northeast and becomes diffuse. Two bright components (N2
and N3), containing most of the flux density are present in the northern jet.
The spectral index of the two components is $\alpha_{N2}\sim-0.99\pm0.12$ and
$\alpha_{N3}\sim-0.84\pm0.23$ ($S\propto\nu^{\alpha}$). Our images show the
presence of an extended structure surrounding component N2, suggestive of
strong interaction between the jet and the interstellar medium (ISM) of the
host galaxy. A steep--spectrum component, labelled as S, located 0.25 ardsec
southwest to the flat--spectrum component which could be the core of 3C 48, is
detected at a significance of $>15\sigma$. Both the location and the steepness
of the spectrum of component S suggest the presence of a counter--jet in 3C 48.


title:
Study the X-ray Dust Scattering Halos with Chandra Observations of
  Cygnus X-3 and Cygnus X-1

abstract:
  We improve the method proposed by Yao \emph{et al} (2003) to resolve the
X-ray dust scattering halos of point sources. Using this method we re-analyze
the Cygnus X-1 data observed with {\it Chandra} (ObsID 1511) and derive the
halo radial profile in different energy bands and the fractional halo intensity
(FHI) as $I(E)=0.402\times E_{{\rm keV}}^{-2}$. We also apply the method to the
Cygnus X-3 data ({\it Chandra} ObsID 425) and derive the halo radial profile
from the first order data with the {\it Chandra} ACIS+HETG. It is found that
the halo radial profile could be fit by the halo model MRN (Mathis, Rumpl $&$
Nordsieck, 1977) and WD01 (Weingartner $&$ Draine, 2001); the dust clouds
should be located at between 1/2 to 1 of the distance to Cygnus X-1 and between
1/6 to 3/4 (from MRN model) or 1/6 to 2/3 (from WD01 model) of the distance to
Cygnus X-3, respectively.


title:
Implications for unified schemes from submillimetre and far-infrared
  follow-up of radio-selected samples

abstract:
  We extend our previous analysis which used generalized luminosity functions
(GLFs) to predict the number of quasars and galaxies in
low-radio-frequency-selected samples as a function of redshift, radio
luminosity, narrow-emission-line luminosity and type of unified scheme. Our
extended analysis incorporates the observed submillimetre (850 micron) flux
densities of radio sources, employs a new method which allows us to deal with
non detections, and focuses on the high-luminosity population. First, we
conclude that the submillimetre luminosity L_{850} of low-frequency-selected
radio sources is correlated with the bolometric luminosity L_{Bol} of their
quasar nuclei via an approximate scaling relation L_{850} \propto L_{Bol}^{0.7
\pm 0.2}. Second, we conclude that there is quantitative evidence for a
receding-torus-like physical process for the high-luminosity population within
a two-population unified scheme for radio sources; this evidence comes from the
fact that radio quasars are brighter in both narrow emission lines and
submillimetre luminosity than radio galaxies matched in radio luminosity and
redshift. Third, we note that the combination of a receding-torus-like scheme
and the assumption that the observed submillimetre emission is dominated by
quasar-heated dust yields a scaling relation L_{850} \propto L_{Bol}^{0.5}
which is within the errors of that determined here for radio-selected quasars,
and consistent with that inferred for radio-quiet quasars by Willott, Rawlings
& Grimes (2003).


title:
A survey for Fe 6.4 keV emission in young stellar objects in rho Oph:
  the strong fluorescence from Elias 29

abstract:
  We report the results of a search for 6.4 keV Fe fluorescent emission in
Young Stellar Objects (YSOs) with measured accretion luminosities in the rho
Oph cloud, using all existing chandra and XMM-Newton observations of the
region. A total of nine such YSOs have X-ray data with sufficiently high S/N
for the 6.4 keV line to be potentially detected if present. A positive
detection of the Fe 6.4 keV line is reported for one object, Elias 29, in both
the XMM-Newton and the chandra data. The 6.4 keV line is detected in Elias 29
both during quiescent and flaring emission, unlikely all previously reported
detections of 6.4 keV Fe fluorescence in YSOs which were made during intense
flaring. The observed equivalent width of the fluorescent line is large, at
W_alpha approx 140 eV, ruling out fluorescence from diffuse circumstellar
material. It is also larger than expected for simple reflection from a
solar-composition photosphere or circumstellar disk, but it is compatible with
being due to fluorescence from a centrally illuminated circumstellar disk. The
X-ray spectrum of Elias 29 is also peculiar in terms of its high (ionized) Fe
abundance, as evident from the very intense Fe xxv 6.7 keV line emission; we
speculate on the possible mechanism leading to the observed high abundance.


title:
Accretion, fluorescent X-ray emission and flaring magnetic structures in
  YSOs

abstract:
  I present some recent developments on high-energy phenomena in YSOs,
concentrating on the new evidence for accretion-induced X-ray emission in YSOs,
for Fe 6.4 keV fluorescent emission from the disks of YSOs and for very long
magnetic structures responsible for intense X-ray flares, likely connecting the
star and the circumstellar disk.


title: Young Massive Clusters in Non-Interacting Galaxies

abstract:
  Young star clusters with masses well in excess of 100.000 Msun have been
observed not only in merger galaxies and large-scale starbursts, but also in
fairly normal, undisturbed spiral and irregular galaxies. Here we present
virial mass estimates for a sample of 7 such clusters and show that the derived
mass-to-light ratios are consistent with "normal" Kroupa-type stellar mass
distributions.


title: What is the origin of the soft excess in AGN?

abstract:
  We investigate the nature of the soft excess below 1 keV observed in AGN. We
use the XMM-Newton data of the low redshift, optically bright quasar, PG
1211+143, and we compare it with the Narrow Line Seyfert 1 galaxy, 1H 0707-495,
which has one of the strongest soft excesses seen. We test various ideas for
the origin of the soft X-ray excess, including a separate spectral component
(for example a low temperature Comptonized component), a reflection-dominated
model, or a complex absorption model. All three can give good fits to the data,
and $\chi^2$ fitting criteria are not sufficient to discriminate among them.
Instead, we favor the complex absorption model on the grounds that it is the
most physically plausible.


title: Evidence for a hot dust-free inner disk around 51 Oph

abstract:
  We report on the observation of CO bandhead emission around 51 Oph (dv=2). A
high resolving power (R~10,000) spectrum was obtained with the infrared
spectrometer ISAAC mounted on VLT-ANTU. Modeling of the profile suggests that
the hot (Tgas=2000-4000K) and dense (n_H>1e10 cm-3) molecular material as
probed by the CO bandhead is located in the inner AU of a Keplerian disk viewed
almost edge-on. Combined with the observation of cooler gas (Tgas=500-900K) by
ISO-SWS and the lack of cold material, our data suggest that the disk around 51
Oph is essentially warm and small. We demonstrate the presence of a dust-free
inner disk that extents from the inner truncation radius until the dust
sublimation radius. The disk around 51 Oph may be in a rare transition state
toward a small debris disk object.


title:
The Neutrino Emissivity of Strange Stars with Ultra Strong Magnetic
  Field

abstract:
  The effect of a strong magnetic field on the dominant neutrino emissivity in
strange stars is investigated. In ultra strong magnetic field, there exists an
enhanced neutrino emission because the charged particles are confined to the
lowest Landau level. The results show that the neutrino emissivity is
proportional to $T^5$ instead of conventional $T^6$, which implies more rapid
cooling behavior in magnetars than usual stars


title:
The distribution of red and blue galaxies in groups: an empirical test
  of the halo model

abstract:
  The popular halo model predicts that the power spectrum of the galaxy
fluctuations is simply the sum of the large scale linear halo-halo power
spectrum and the weighted power spectrum of the halo profile. Previous studies
have derived halo parameters from the observed galaxy correlation function.
Here we test the halo model directly for self-consistency with a minimal set of
theoretical assumptions by utilising the 2dF Galaxy Redshift Survey (2dFGRS).
We derive empirically the halo occupation and galaxy radial distributions in
the haloes of the 2dF Percolation-Inferred Galaxy Group (2PIGG) catalogue. The
mean halo occupation number is found to be well-fitted by a power-law, <N|M> ~
M^b, at high masses, with b = 1.05, 0.88, 0.99 for red, blue and all galaxies
respectively (with 1-sigma errors of 15-19%). We find that the truncated NFW
profile provides a good fit to the galaxy radial distributions, with
concentration parameters c=3.9, 1.3, 2.4 for red, blue and all galaxies
respectively (with 1-sigma errors of 8-15%). Adding the observed linear power
spectrum to these results, we compare these empirical predictions of the halo
model with the observed correlation functions for these same 2dF galaxy
populations. We conclude that subject to some fine tuning it is an acceptable
model for the two-point correlations. Our analysis also explains why the
correlation function slope of the red galaxies is steeper than that of the blue
galaxies. It is mainly due to the number of red and blue galaxies per halo,
rather than the radial distribution within the haloes of the two galaxy
species.


title: Madam - a map-making method for CMB experiments

abstract:
  We present a new map-making method for CMB measurements. The method is based
on the destriping technique, but it also utilizes information about the noise
spectrum. The low-frequency component of the instrument noise stream is
modelled as a superposition of a set of simple base functions, whose amplitudes
are determined by means of maximum-likelihood analysis, involving the
covariance matrix of the amplitudes. We present simulation results with $1/f$
noise and show a reduction in the residual noise with respect to ordinary
destriping. This study is related to \Planck LFI activities.


title: Ram pressure stripping of disk galaxies

abstract:
  (Abridged) We perform high resolution 2D hydrodynamical simulations of
face-on ram pressure stripping (RPS) of disk galaxies to compile a
comprehensive parameter study varying galaxy properties (mass, vertical
structure of the gas disk) and covering a large range of ICM conditions,
reaching from high density environments like in cluster centres to low density
environments typical for cluster outskirts or groups. We find that the ICM-ISM
interaction proceeds in three phases: firstly the instantaneous stripping
phase, secondly the dynamic intermediate phase, thirdly the quasi-stable
continuous viscous stripping phase. The stripping efficiency depends slightly
on the Mach number of the flow, however, the main parameter is the ram
pressure. The stripping efficiency does not depend on the vertical structure
and thickness of the gas disk. We discuss uncertainties in the classic estimate
of the stripping radius of \citet{gunn72}, and adapt the estimate used by
\cite{mori00} for spherical galaxies, (comparison of central pressure with ram
pressure). We find that the latter estimate predicts the radius and mass of the
gas disk remaining at the end of the second phase very well, and better than
the \citet{gunn72} criterion. From our simulations we conclude that gas disks
of galaxies in high density environments are heavily truncated or even
completely stripped, but also the gas disks of galaxies in low density
environments are disturbed by the flow and back-falling material, so that they
should also be pre-processed.


title: Fundamental stellar parameters

abstract:
  I present a discussion of fundamental stellar parameters and their
observational determination in the context of interferometric measurements with
current and future optical/infrared interferometric facilities. Stellar
parameters and the importance of their determination for stellar physics are
discussed. One of the primary uses of interferometry in the field of stellar
physics is the measurement of the intensity profile across the stellar disk,
both as a function of position angle and of wavelength. High-precision
fundamental stellar parameters are also derived by characterizations of binary
and multiple system using interferometric observations. This topic is discussed
in detail elsewhere in these proceedings. Comparison of observed spectrally
dispersed center-to-limb intensity variations with models of stellar
atmospheres and stellar evolution may result in an improved understanding of
key phenomena in stellar astrophysics such as the precise evolutionary effects
on the main sequence, the evolution of metal-poor stars, stellar pulsation,
mass-loss from high-mass main-sequence stars as well as from evolved stars,
circumstellar environments, stellar magnetic activity, stellar rotation, and
convection and turbulent mixing. Examples of already achieved results with
existing interferometric facilities and anticipated improvements during the
VLTI era are described. A science case for a next-generation optical/infrared
interferometric facilities is presented, and the required specifications to
achieve it are given. Finally, important synergy effects with external
facilities in order to reach a more complete picture are discussed.


title: TeV mu Neutrinos from Young Neutron Stars

abstract:
  Neutron stars are efficient accelerators for bringing charges up to
relativistic energies. We show that if positive ions are accelerated to ~1 PeV
near the surface of a young neutron star (t_age < about 10^5 yr), protons
interacting with the star's radiation field will produce beamed mu neutrinos
with energies of ~50 TeV that could produce the brightest neutrino sources at
these energies yet proposed. These neutrinos would be coincident with the radio
beam, so that if the star is detected as a radio pulsar, the neutrino beam will
sweep the Earth; the star would be a ``neutrino pulsar''. Looking for muon
neutrino emission from young neutron stars will provide a valuable probe of the
energetics of the neutron star magnetosphere.


title:
XMM-Newton EPIC observations of the ultraluminous X-ray source NGC 5204
  X-1

abstract:
  We present the results of two XMM-Newton observations of the ultraluminous
X-ray source (ULX) NGC 5204 X-1. The EPIC spectra are well-fit by the standard
spectral model of a black-hole X-ray binary, comprising a soft multi-colour
disc blackbody component plus a harder power-law continuum. The cool (kT_in ~
0.2 keV) inner-disc temperature required by this model favours the presence of
an intermediate-mass black hole (IMBH) in this system, though we highlight a
possible anomaly in the slope of the power-law continuum in such fits. We
discuss the interpretation of this and other, non-standard spectral modelling
of the data.


title: Interferometry and the study of binaries

abstract:
  To determine the parameters (masses, orbital period) of a binary, one
requires among others the inclination, which is best determined from a visual
orbit. The next generation of interferometers can provide visual orbits for a
large number of binaries. We then can investigate with what parameters binaries
are born, and how these parameters evolve, and thus understand the galactic
binary population. Results can be obtained quickly by carefully selecting
binaries for the study of evolutionary processes. Full knowledge of properties
of binaries at birth requires a large, dedicated programme, which is best
limited to spectroscopic binaries with primary masses >0.8Msun and orbital
periods <50yr.


title:
Cluster AgeS Experiment (CASE): SX Phe stars from the globular cluster
  Omega Centauri

abstract:
  We present an analysis and interpretation of oscillation spectra for all 69
SX Phoenicis stars discovered in the field of the cluster. For most of the
stars we have reliable absolute magnitudes and colors. Except of one, or
perhaps two, objects, the stars are cluster members. Their pulsational
behaviour is very diversified. Multiperiodic variability with at least part of
the excited modes being nonradial is most common but there are also many cases
of high amplitude, presumably radial mode, pulsators. In a number of such cases
we have evidence for two radial modes being excited. Parameters of radial mode
pulsators are in most cases consistent with standard evolutionary models for
stars in the mass range 0.9-1.15 Mo. However, in four cases we have evidence
that the masses are significantly lower than expected. Three objects show
frequency triplets that may be interpreted in terms of rotational frequency
splitting of l=1 modes. Implied equatorial velocities of rotation are from 10
to over 100 km/s. Nearly all measured frequencies fall in the ranges predicted
for unstable modes. Two cases of low frequency variability are interpreted as
being caused by tidal distortion induced by close companions.


title: X-ray sources in globular clusters

abstract:
  Observations with BeppoSAX, RXTE and Chandra suggest that many of the bright
X-ray sources in globular clusters have ultrashort binary periods. This is
remarkable as such systems are not easily formed. With accurate optical
astrometry of HST images, the large numbers of low-luminosity X-ray sources
discovered with Chandra can be classified as quiescent low-mass X-ray binaries,
pulsars, cataclysmic variables, and magnetically active binaries. The number of
cataclysmic variables is found to scale with the number of close stellar
encounters.


title: Ultrahigh Energy Nuclei Propagation in a Structured, Magnetized Universe

abstract:
  We compare the propagation of iron and proton nuclei above 10^19 eV in a
structured Universe with source and magnetic field distributions obtained from
a large scale structure simulation and source densities about 10^(-5) Mpc^(-3).
All relevant cosmic ray interactions are taken into account, including
photo-disintegration and propagation of secondary products. Iron injection
predicts spectral shapes different from proton injection which disagree with
existing data below about 30 EeV. Injection of light nuclei or protons must
therefore contribute at these energies. However, at higher energies, existing
data are consistent with injection of pure iron with spectral indices between 2
and 2.4. This allows a significant recovery of the spectrum above roughly 100
EeV, especially in the case of large deflections. Significant auto-correlation
and anisotropy, and considerable cosmic variance are also predicted in this
energy range. The mean atomic mass A fluctuates considerably between different
scenarios. At energies below 60 EeV, if the observed A > 35, magnetic fields
must have a negligible effect on propagation. At the highest energies the
observed flux will be dominated by only a few sources whose location may be
determined by next generation experiments to within 10-20 degrees even if
extra-galactic magnetic fields are important.


title:
Present Evidence for Intermediate Mass Black Holes in ULXs and Future
  Prospects

abstract:
  In a number of the most luminous ULXs (L ~ 1 E+40 erg/s) in nearby galaxies,
observations with XMM-Newton and Chandra are revealing evidence which suggests
that these ULXs may harbor intermediate-mass black holes (IMBHs). The detection
of accretion disk spectral components with temperatures 5-10 times lower than
the temperatures observed in stellar-mass black hole binaries near to their
Eddington limit may be particularly compelling evidence for IMBH primaries,
since T ~ M^(-1/4) for disks around black holes. In some sources, X-ray timing
diagnostics also hint at IMBHs. Evidence for IMBHs in a subset of the most
luminous ULXs, a discussion of the robustness of this evidence and alternatives
to the IMBH interpretation, and prospects for better determining the nature of
these sources in the future, are presented in this work.


title:
Discovery of a Be/X-ray Binary Consistent with the Position of GRO
  J2058+42

abstract:
  GRO J2058+42 is a 195 s transient X-ray pulsar discovered in 1995 with BATSE.
In 1996, RXTE located GRO J2058+42 to a 90% confidence error circle with a 4'
radius. On 20 February 2004, the region including the error circle was observed
with Chandra ACIS-I. No X-ray sources were detected within the error circle,
however, 2 faint sources were detected in the ACIS-I field-of-view. We obtained
optical observations of the brightest object, CXOU J205847.5+414637, that had
about 64 X-ray counts and was just 0.3' outside the error circle. The optical
spectrum contained a strong H alpha line and corresponds to an infrared object
in the 2MASS catalog, indicating a Be/X-ray binary system. Pulsations were not
detected in the Chandra observations, but similar flux variations and distance
estimates suggest that CXOU J205847.5+414637 and GRO J2058+42 are the same
object. We present results from the Chandra observation, optical observations,
new and previously unreported RXTE observations, and a reanalysis of a ROSAT
observation.


title: High altitude wind velocity at Sierra Negra and San Pedro M\'artir

abstract:
  It has been proposed that the global circulation of the atmosphere winds at
200 mb can be used as a criteria to establish the suitability of a site for the
development of adaptive optics techniques such as slow wavefront corrugation
correction. By using the NOAA NCEP/NCAR Reanalysis data base we analyze the
monthly average wind velocity at 200 mb for a 16 year period, for two sites in
Mexico: Sierra Negra and San Pedro M\'artir. We compare the results with those
obtained for Mauna Kea, Paranal and La Silla, with Maidanak in Uzbekistan, and
with Gamsberg in Namibia. We show that for all the sites under study there is a
yearly wind speed modulation and we model that modulation. Our results show
that Sierra Negra and San Pedro M\'artir are comparable with the best
observatory sites as Mauna Kea and are amongst the most advantageous sites to
apply adaptive optics techniques.


title: Particle acceleration and non-thermal emission from galaxy clusters

abstract:
  The existence and extent of non-thermal phenomena in galaxy clusters is now
well established. A key question in our understanding of these phenomena is the
origin of the relativistic electrons which may be constrained by the modelling
of the fine radio properties of radio halos and of their statistics. In this
paper we argue that present data favour a scenario in which the emitting
electrons in the intracluster medium (ICM) are reaccelerated in situ on their
way out. An overview of turbulent-particle acceleration models is given
focussing on recent time-dependent calculations which include a full coupling
between particles and MHD waves.


title: Constraints on the star formation history of the Large Magellanic Cloud

abstract:
  We present the analysis of deep colour-magnitude diagrams (CMDs) of 6 stellar
fields in the LMC. The data were obtained using HST/WFPC2 in the I and V
filters, reaching V=26.5. We discuss and apply a method of correcting CMDs for
photometric incompleteness. A method to generate artificial CMDs based on a
model star formation history is also developed. This method incorporates
photometric error effects, unresolved binaries, reddening and allows use of
different forms of the initial mass function and of the SFH itself. We use the
Partial Models Method, as presented by Gallart and others, for CMD modelling,
and include control experiments to prove its validity in a search for
constraints on the Large Magellanic Cloud star formation history in different
regions. Reliable star formation histories for each field are recovered by this
method. In all fields, a gap in star formation with t=700 Myrs is observed.
Field-to-field variations have also been observed. The two fields near the LMC
bar present some significant star forming events, having formed both young (t <
1Gyr) and old (t > 10 Gyrs) stars, with a clear gap from 3-6 Gyrs. Two other
fields display quite similar SFHs, with increased star formation having taken
place at t=2-3 Gyrs and 6 < t < 10 Gyrs. The remaining two fields present star
formation histories closer to uniform, with no clear event of enhanced star
formation.


title:
The Optical and Ultraviolet Spectral Energy Distributions of Short
  Period Black Hole X-ray Transients in Outburst

abstract:
  We compile optical and UV spectra of a sample of 'typical' short period black
hole X-ray transients in outburst. We also survey determinations of
interstellar extinction and distance in order to deredden spectra and compare
absolute fluxes. Hence we perform a comparative study of the broad-band
spectral energy distributions (SED). We find that given such a homogeneous
sample of typical sources, the optical SEDs form a relatively uniform set, all
exhibiting quasi-power-law spectra with Fnu proportional to nu^alpha, where
0.5<alpha<1.5 (steeper than the canonical nu^1/3 disk spectrum). All become
flatter in the UV, although there is more diversity here. The SEDs studied can
be broadly divided into two optical-UV spectral states. The UV-hard spectra,
e.g. A0620-00 and X-ray Nova Muscae 1991, continue to rise in the far-UV. The
UV-soft spectra, e.g. GRO J0422+32, drop off. XTE J1859+226 evolved from
UV-soft to UV-hard as it decayed indicating that this effect is a real
difference, not a dereddening artifact. All of the spectra can be fitted by a
generalized black body disk model with two forms of heating, resulting in the
two states. The UV-soft state is consistent with a disk illuminated by a
central point source, with irradiative heating dominating over viscous. The
UV-hard state is well described by a viscously heated disk, although this
requires very high mass flow rates in the case of Nova Muscae. Alternatively, a
UV-hard spectrum can be produced if the disk is illuminated by a vertically
extended X-ray source such as a central scattering corona or jet. [Abridged]


title: A high-energy view of radio-loud AGN

abstract:
  Seyfert galaxies and quasars were first discovered through optical and radio
techniques, but in recent years high-energy emission, that can penetrate
central gas and dust, has become essentially the defining characteristic of an
AGN. AGNs with extended radio jets are of particular interest, since the jets
signal source orientation. However, the jets extend into the cores, where they
are faster and more compact. Special-relativistic effects then cause jet
brightness and variability time-scales across the electromagnetic spectrum to
be strong functions of jet orientation. Jet X-ray emission is confused, to
varying degrees, with that from the central engine, but can be measured, at
least in a statistical sense, through considerations of the multiwaveband
spectrum and the level of intrinsic absorption. The rich high-energy structures
found in jets which are resolved with Chandra inform our interpretation of the
inner structures. In particular, it is found that shocks are prevalent and
don't necessarily disrupt jets, and that one-zone models of emission near
shocks are an over-simplification.


title: An Improved Estimate of the Mass of Dust in Cassiopeia A

abstract:
  Recent observations of sub-millimeter continuum emission toward supernova
remnants (SNR) have raised the question of whether such emission is caused by
dust within the SNR and thus produced by the supernova itself or along the
line-of-sight. The importance of the present work is to establish evidence for
the production of large amounts of dust in supernovae. The best tests can be
made for young supernovae in our galaxy. Cassiopeia A is the best candidate for
a measurement.


title: Relativistic MHD simulations of pulsar bow-shock nebulae

abstract:
  Pulsar bow-shock nebulae are a class of pulsar wind nebulae (PWNe) that form
when the pulsar wind is confined by the ram pressure of the ambient medium, and
are usually associated with old pulsars, that have already emerged from the
progenitor Supernova Remnant (SNR). Until a few years ago these nebulae were
mainly observed as \halpha sources; recently, also non-thermal emission has
been detected. This is the signature of accelerated particles gyrating in a
magnetic field. In the same way as \halpha radiation is a tool for studying the
layer of shocked Interstellar Medium (ISM), the non-thermal radiation might be
used to infer the properties of the shocked pulsar wind. However theoretical
and numerical models have been presented so far only in the hydrodynamical (HD)
regime, while in order to properly model the internal flow structure and the
emission properties of these nebulae a magnetohydrodynamical (MHD) treatment is
required. We present here relativistic MHD (RMHD) axisymmetric simulations of
pulsar wind bow-shock nebulae. The structure and fluid dynamics of such objects
is investigated for various values of the pulsar wind magnetization. Simulated
synchrotron maps are computed and comparison of the emission pattern with
observations is discussed.


title: Bayesian evidence as a tool for comparing datasets

abstract:
  We introduce a new conservative test for quantifying the consistency of two
or more datasets. The test is based on the Bayesian answer to the question,
``How much more probable is it that all my data were generated from the same
model system than if each dataset were generated from an independent set of
model parameters?''. We make explicit the connection between evidence ratios
and the differences in peak chi-squared values, the latter of which are more
widely used and more cheaply calculated. Calculating evidence ratios for three
cosmological datasets (recent CMB data (WMAP, ACBAR, CBI, VSA), SDSS and the
most recent SNe Type 1A data) we find that concordance is favoured and the
tightening of constraints on cosmological parameters is indeed justified.


title:
Spectroscopic-Like Temperature of Clusters of Galaxies and Cosmological
  Implications

abstract:
  The thermal properties of hydrodynamical simulations of galaxy clusters are
usually compared to observations by relying on the emission-weighted
temperature T_ew, instead of on the spectroscopic X-ray temperature T_spec,
which is obtained by actual observational data. Here we show that, if the
intra-cluster medium is thermally complex, T_ew fails at reproducing T_spec. We
propose a new formula, the spectroscopic-like temperature, T_sl, which
approximates T_spec better than a few per cent. By analyzing a set of
hydrodynamical simulations of galaxy clusters, we also find that T_sl is lower
than T_ew by 20-30 per cent. As a consequence, the normalization of the M-T
relation from the simulations is larger than the observed one by about 50 per
cent. If masses in simulated clusters are estimated by following the same
assumptions of hydrostatic equilibrium and beta-model gas density profile, as
often done for observed clusters, then the M-T relation decreases by about 40
per cent, and significantly reduces its scatter. Based on this result, we
conclude that using the observed M-T relation to infer the amplitude of the
power spectrum from the X--ray temperature function could bias low sigma_8 by
10-20 per cent. This may alleviate the tension between the value of sigma_8
inferred from the cluster number density and those from cosmic microwave
background and large scale structure.


title:
A Simultaneous RXTE and XMM-Newton Observation of the Broad-Line Radio
  Galaxy 3C 111

abstract:
  We present the results of simultaneous XMM-Newton and RXTE observations of
the Broad-Line Radio Galaxy 3C 111. We find that the Compton reflection bump is
extremely weak, however, broad residuals are clearly present in the spectrum
near the Fe Kalpha emission line region. When fitted with a Gaussian emission
line,the feature has an equivalent width of 40-100eV and full-width at half
maximum of greater than 20,000 km/s, however the exact properties of this weak
line are highly dependent upon the chosen continuum model. The width of the
line suggests an origin in the inner accretion disk, which is, however,
inconsistent with the lack of Compton reflection. We find that much of the
broad residual emission can be attributed to continuum curvature. The data are
consistent with a model in which the primary powerlaw continuum is reprocessed
by an accretion disk which is truncated as small radii. Alternatively, the
primary source could be partially covered by a dense absorber. The latter model
is less attractive than the former because of the small inclination angle of
the jet of 3C 111 to the line of sight. We consider it likely that the curved
continuum of the partial covering model is fortuitously similar to the
continuum shape of the reprocessing model. In both models, the fit is greatly
improved by the addition of an unresolved Fe K alpha emission line, which could
arise either in a Compton-thin obscuring torus or dense clouds lying along the
line of sight. We also find that there are unacceptable residuals at low
energies in the MOS data in particular, which were modeled as a Gaussian with
an energy of ~1.5 keV; we attribute these residuals to calibration
uncertainties of the MOS detectors.


title:
The Importance of Intergalactic Structure to Gravitationally Lensed
  Quasars

abstract:
  Image flux ratio anomalies have been attributed to substructures within the
gravitational lens and to small mass halos (M <~ 10^10 Msun) in intergalactic
space. In this paper, analytic calculations are presented that help in the
understanding of how intergalactic halos affect magnification ratios. It is
found that intergalactic halos can produce anomalies at a similar level to
those that are observed. Intergalactic halos with masses <10^10 Msun are
expected to cause relative deflections between images of order 10
milliarcseconds, which are then magnified by the primary lens. They will also
cause fluctuations in the surface density on the several percent level. The
importance of intergalactic halos depends strongly on the radial profile of the
halos and the primordial power spectrum at small scales. Strongly lensed
quasars provide an opportunity to probe these properties. A strong dependence
on the QSO redshift is predicted and can be used to distinguish between
intergalactic structure and substructure as the cause of magnification
anomalies. This analytic approach also explains why some previous semi-analytic
estimates disagreed with numerical calculations.


title: A Far-Ultraviolet Spectroscopic Survey of Luminous Cool Stars

abstract:
  FUSE ultraviolet spectra of 8 giant and supergiant stars reveal that high
temperature (3 X 10^5 K) atmospheres are common in luminous cool stars and
extend across the color-magnitude diagram from Alpha Car (F0 II) to the cool
giant Alpha Tau (K5 III). Emission present in these spectra includes
chromospheric H-Lyman Beta, Fe II, C I, and transition region lines of C III, O
VI, Si III, Si IV. Emission lines of Fe XVIII and Fe XIX signaling temperatures
of ~10^7 K and coronal material are found in the most active stars, Beta Cet
and 31 Com. A short-term flux variation, perhaps a flare, was detected in Beta
Cet during our observation. Stellar surface fluxes of the emission of C III and
O VI are correlated and decrease rapidly towards the cooler stars, reminiscent
of the decay of magnetically-heated atmospheres. Profiles of the C III (977A)
lines suggest that mass outflow is underway at T~80,000 K, and the winds are
warm. Indications of outflow at higher temperatures (3 X 10^5K) are revealed by
O VI asymmetries and the line widths themselves. High temperature species are
absent in the M-supergiant Alpha Ori. Narrow fluorescent lines of Fe II appear
in the spectra of many giants and supergiants, apparently pumped by H Lyman
Alpha, and formed in extended atmospheres. Instrumental characteristics that
affect cool star spectra are discussed.


title:
XMM-Newton Detection of Hot Gas in the Eskimo Nebula: Shocked Stellar
  Wind or Collimated Outflows?

abstract:
  The Eskimo Nebula (NGC 2392) is a double-shell planetary nebula (PN) known
for the exceptionally large expansion velocity of its inner shell, ~90 km/s,
and the existence of a fast bipolar outflow with a line-of-sight expansion
velocity approaching 200 km/s. We have obtained XMM-Newton observations of the
Eskimo and detected diffuse X-ray emission within its inner shell. The X-ray
spectra suggest thin plasma emission with a temperature of ~2x10^6 K and an
X-ray luminosity of L_X = (2.6+/-1.0)x10^31 (d/1150 pc)^2 ergs/s, where d is
the distance in parsecs. The diffuse X-ray emission shows noticeably different
spatial distributions between the 0.2-0.65 keV and 0.65-2.0 keV bands.
High-resolution X-ray images of the Eskimo are needed to determine whether its
diffuse X-ray emission originates from shocked fast wind or bipolar outflows.


title:
The Multimission Archive at the Space Telescope Science Institute in the
  context of VO activities

abstract:
  In the past year, the Multimission Archive at the Space Telescope Science
Institute (MAST) has taken major steps in making MAST's holdings available
using VO-defined protocols and standards, and in implementing VO-based tools.
For example, MAST has implemented the Simple Cone Search protocol, and all MAST
mission searches may be returned in the VOTable format, allowing other archives
to use MAST data for their VO applications. We have made many of our popular
High Level Science Products available through Simple Image Access Protocol
(SIAP), and are implementing the VO Simple Spectral Access Protocol (SSAP). The
cross correlation of VizieR catalogs with MAST missions is now possible, and
illustrates the integration of VO services into MAST. The user can easily
display the results from searches within MAST using the plotting tool VOPlot.
MAST also participates in the NVO registry service. Thus, the user can harvest
MAST holdings simultaneously with data from many other surveys and missions
through the VO DataScope Data Inventory Service.


title:
Determining the Physical Properties of the B Stars II. Calibration of
  Synthetic Photometry

abstract:
  We present a new calibration of optical (UBV, Stromgren, uvby-beta, and
Geneva) and near IR (Johnson RIJHK and 2MASS) photometry for B and early A
stars derived from Kurucz (1991) Atlas model atmospheres. Our sample of stars
consists of 45 normal, nearby B and early A stars which have high quality, low
resolution IUE spectra and accurate Hipparcos parallaxes. The calibration is
unique because it relies only on the UV spectral energy distributions, the
absolute flux calibration of the V filter and the Hipparcos distances to
determine the appropriate model atmospheres for the program stars. These models
are then used to calibrate the synthetic photometry. We compare our results
with previous, well accepted results and provide a thorough discussion of the
random errors and systematic effects affecting the calibration. In particular,
we demonstrate the influence of vsini on surface gravities derived from fitting
model atmospheres. Finally, we discuss some of our intended applications of
this new calibration.


title: Fifty Years of IMF Variation: The Intermediate-Mass Stars

abstract:
  I track the history of star count estimates of the Milky Way field star and
open cluster IMFs, concentrating on the neglected mass range from 1 to 15
M${_\odot}$. The prevalent belief in a universal IMF appears to be without
basis for this mass range. Two recent estimates of the field star IMF using
different methods and samples give values of the average logarithmic slope
$\Gamma$ between -1.7 and -2.1 in the mass range 1.1 to 4 M${_\odot}$. Two
older estimates between 2 and 15 M${_\odot}$ disagree severely; the field IMF
in this range is essentially unknown from star counts. Variations in $\Gamma$
among open cluster IMFs in this mass range have not decreased despite numerous
detailed studies, even for studies using homogeneous data and reduction
procedures and including only clusters with a significant mass range. These
cluster variations \textit{might} be due to the combined effects of sampling,
systematic errors, stellar evolution uncertainties, dynamical evolution, and
unresolved binaries. If so, then the cluster data are consistent with a
universal IMF, but are also consistent with sizeable variations. The cluster
data do not allow an estimate of an average IMF or $\Gamma$ because the average
depends on the choice of weighting procedure and other effects. If the spread
in cluster IMFs is in excess of the effects listed above, real IMF variations
must occur that do not depend much on physical conditions explored so far. The
complexity of the star formation process seen in observations and simulations
suggests that large realization-to-realization differences might be expected,
in which case an individual cluster IMF would be in part the product of
evolutionary contingency in star formation, and the function of interest is the
probability distribution of IMF parameters.


title:
APS Neutrino Study: Report of the Neutrino Astrophysics and Cosmology
  Working Group

abstract:
  In 2002, Ray Davis and Masatoshi Koshiba were awarded the Nobel Prize in
Physics ``for pioneering contributions to astrophysics, in particular for the
detection of cosmic neutrinos.'' However, while astronomy has undergone a
revolution in understanding by synthesizing data taken at many wavelengths, the
universe has only barely been glimpsed in neutrinos, just the Sun and the
nearby SN 1987A. An entire universe awaits, and since neutrinos can probe
astrophysical objects at densities, energies, and distances that are otherwise
inaccessible, the results are expected to be particularly exciting. Similarly,
the revolution in quantitative cosmology has heightened the need for very
precise tests that depend on the effects of neutrinos, and prominent among them
is the search for the effects of neutrino mass, since neutrinos are a small but
known component of the dark matter. In this report, we highlight some of the
key opportunties for progress in neutrino astrophysics and cosmology, and the
implications for other areas of physics.


title: X-ray Observations of the Bright Old Nova V603 Aquilae

abstract:
  We report on our Chandra and RXTE observations of the bright old nova, V603
Aql, performed in 2001 April, supplemented by our analysis of archival X-ray
data on this object. We find that the RXTE data are contaminated by the
Galactic Ridge X-ray emission. After accounting for this effect, we find a high
level of aperiodic variability in the RXTE data, at a level consistent with the
uncontaminated Chandra data. The Chandra HETG spectrum clearly originates in a
multi-temperature plasma. We constrain the possible emission measure
distribution of the plasma through a combination of global and local fits. The
X-ray luminosity and the spectral shape of V603 Aql resemble those of SS Cyg in
transition between quiescence and outburst. The fact that the X-ray flux
variability is only weakly energy dependent can be interpreted by supposing
that the variability is due to changes in the maximum temperature of the
plasma. The plasma density is likely to be high, and the emission region is
likely to be compact. Finally, the apparent overabundance of Ne is consistent
with V603 Aql being a young system.


title: Cascades from $\nu_e$ above $10^{20}$ eV

abstract:
  At very high energies, the Landau-Pomeranchuk-Migdal effect reduces the cross
sections for electron bremsstrahlung and photon $e^+e^-$ pair production. The
fractional electron energy loss and pair production cross sections drop as the
energy increases. In contrast, the cross sections for photonuclear interactions
grow with energy. In solids and liquids, at energies above $10^{20}$ eV,
photonuclear reactions dominate, and showers that originate as photons or
electrons quickly become hadronic showers. These electron-initiated hadronic
showers are much shorter (due to the absence of the LPM effect), but wider than
purely electromagnetic showers would be. This change in shape alters the
spectrum of the electromagnetic and acoustic radiation emitted from the shower.
These alterations have important implications for existing and planned searches
for radiation from $\nu_e$ induced showers above $10^{20}$ eV, and some
existing limits should be reevaluated.


title: The Halo, Hot Spots and Jet/Cloud Interaction of PKS 2153--69

abstract:
  We report Chandra X-ray Observatory and 1.4 GHz Australian Long Baseline
Array (LBA) observations of the radio galaxy PKS 2153--69 and its environment.
The Chandra image reveals a roughly spherical halo of hot gas extending out to
30 kpc around PKS 2153--69. Two depressions in the surface brightness of the
X-ray halo correspond to the large scale radio lobes, and interpreting these as
cavities inflated with radio plasma we infer a jet power of 4x10^42 erg/s. Both
radio lobes contain hot spots that are detected by Chandra. In addition, the
southern hot spot is detected in the 1.4 GHz LBA observation, providing the
highest linear resolution image of a radio lobe hot spot to date. The northern
hot spot was not detected in the LBA observation. The radio to X-ray spectra of
the hot spots are consistent with a simple power law emission model. The
nucleus has an X-ray spectrum typical of a type 1 active galactic nucleus, and
the LBA observation shows a one-sided nuclear jet on 0.1" scales. Approximately
10" northeast of the nucleus, X-ray emission is associated with an
extra-nuclear cloud. The X-ray emission from the cloud can be divided into two
regions, an unresolved western component associated with a knot of radio
emission (in a low resolution map), and a spatially extended eastern component
aligned with the pc-scale jet and associated with highly ionized optical
line-emitting clouds. The X-ray spectrum of the eastern component is very soft
(Gamma > 4.0 for a power law model or kT ~0.22 keV for a thermal plasma). The
LBA observation did not detect compact radio emission from the extra-nuclear
cloud. (Abstract truncated).


title:
Astrometric and Spectroscopic Confirmation of a Brown Dwarf Companion to
  GSC 08047-00232

abstract:
  We report VLT/NACO imaging observations of the stars GSC 08047-00232 and HIP
6856, probable members of the large Tucana-Horologium association. During our
previous ADONIS/SHARPII deep imaging survey, a substellar candidate companion
was discovered around each star. Based on VLT/NACO astrometric measurements, we
find that GSC 08047-00232 and the faint candidate companion near to it share
the same proper motion with a significance of 3.1sigma. On the contrary, the
candidate companion to HIP 6856 is probably a background object with a
significance of 4.3sigma. We also detect a new fainter and closer candidate
companion to HIP 6856, but which is likely a background object too with a
significance of 4sigma. Recent VLT/NACO spectroscopic measurements of GSC
08047-00232 finally confirm the substellar nature of this young brown dwarf
with a derived spectral type M9.5. GSC 08047-00232 B, with an estimated mass of
25MJup and an effective temperature of 2100K, is presently the third substellar
companion identified among young, nearby associations.


title: The Center of Activity in the CSS Superluminal Source 3C 138

abstract:
  We present the results from the first quasi-simultaneous multi-frequency
(2.3, 5.0, 8.4 and 15 GHz) Very Long Baseline Interferometry (VLBI)
observations of a compact steep spectrum (CSS) superluminal source 3C138. For
the first time, the spectral distribution of the components within its central
10 milli-arcsecond (mas) region was obtained. This enables us to identify the
component at the western end as the location of the nuclear activity on the
assumption that the central engine is associated with one of the detected
components. The possibility that none of these visible components is the true
core is also discussed. The new measurements further clarify the superluminal
motions of its inner jet components. The multi-frequency data reveal a convex
spectrum in one jet component, inferring the existence of free-free absorption
by the ambient dense plasma.


title:
First microlensing candidate towards M31 from the Nainital Microlensing
  Survey

abstract:
  We report our first microlensing candidate NMS-E1 towards M31 from the data
accumulated during the four years of Nainital Microlensing Survey. Cousin R and
I band observations of ~13'x13' field in the direction of M31 have been carried
out since 1998 and data is analysed using the pixel technique proposed by the
AGAPE collaboration. NMS-E1 lies in the disk of M31 at \alpha = 0:43:33.3 and
\delta = +41:06:44, about 15.5 arcmin to the South-East direction of the center
of M31. The degenerate Paczy\'{n}ski fit gives a half intensity duration of ~59
days. The photometric analysis of the candidate shows that it reached R~20.1
mag at the time of maximum brightness and the colour of the source star was
estimated to be (R-I)_0 ~ 1.1 mag. The microlensing candidate is blended by red
variable stars; consequently the light curves do not strictly follow the
characteristic Paczy\'{n}ski shape and achromatic nature. However its long
period monitoring and similar behaviour in R and I bands supports its
microlensing nature.


title: CMB lensing extraction and primordial non-Gaussianity

abstract:
  The next generation of CMB experiments should get a better handle on
cosmological parameters by mapping the weak lensing deflection field, which is
separable from primary anisotropies thanks to the non-Gaussianity induced by
lensing. However, the generation of perturbations in the Early Universe also
produces a level of non-Gaussianity which is known to be small, but can
contribute to the anisotropy trispectrum at the same level as lensing. In this
work, we study whether the primordial non-Gaussianity can mask the lensing
statistics. We concentrate only on the ``temperature quadratic estimator'' of
lensing, which will be nearly optimal for the Planck satellite, and work in the
flat-sky approximation. We find that primordial non-Gaussianity contaminates
the deflection field estimator by roughly (0.1 f_NL)% at large angular scales,
which represents at most a 10% contribution, not sufficient to threaten lensing
extraction, but enough to be taken into account.


title:
Cosmochemistry, Cosmology and Fundamental Constants: High-Resolution
  Spectroscopy of Damped Lyman-Alpha Systems

abstract:
  Spectroscopy of QSO absorption lines provides essential observational input
for the study of nucleosynthesis and chemical evolution of galaxies at high
redshift. But new observations may indicate that present chemical abundance
data are biased due to deficient spectral resolution and unknown selection
effects: Recent high-resolution spectra reveal the hitherto unperceived
chemical nonuniformity of a molecule-bearing damped Lyman-alpha (DLA) system,
and the still ongoing H/ESO DLA survey produces convincing evidence for the
effect of dust attenuation. We present a revised analysis of the moleculecular
hydrogen-bearing DLA complex toward the QSO HE 0515-4414 showing nonuniform
differential depletion of chemical elements onto dust grains, and introduce the
H/ESO DLA survey and its implications. Conclusively, we aim at starting an
unbiased chemical abundance database established on high-resolution
spectroscopic observations. New data to probe the temperature-redshift relation
predicted by standard cosmology and to test the constancy of fundamental
constants will be potential spin-offs.


title:
Formation and evolution of dwarf elliptical galaxies I. Structural and
  kinematical properties

abstract:
  This paper is the first in a series in which we present the results of an ESO
Large Program on the kinematics and internal dynamics of dwarf elliptical
galaxies (dEs). We investigate the relations between the parameters that
quantify the structure and internal dynamics of dEs such as the Faber_Jackson
relation and the Fundamental Plane (FP).
  We show that the dE sequences in the various diagrams are disjunct from those
traced by bright and intermediate-luminosity elliptical galaxies and bulges of
spirals. It appears that semi-analytical models (SAMs) are able to reproduce
the position of the dEs in those diagrams.
  While these findings are clearly a success for the hierarchical-merging
picture of galaxy formation, they do not necessarily invalidate the alternative
``harassment'' scenario, which posits that dEs stem from perturbed and stripped
late-type disk galaxies that entered clusters and groups of galaxies about 5
Gyr ago.


title: Gamma-ray bursts: Potential sources of ultra high energy cosmic-rays

abstract:
  The arguments suggesting an association between the sources of cosmological
gamma-ray bursts (GRBs) and the sources of ultra-high energy cosmic rays
(UHECRs) are presented. Recent GRB and UHECR observations are shown to
strengthen these arguments. Predictions of the GRB model for UHECR production,
that may be tested with large area high energy cosmic-ray detectors which are
either operating or under construction, are outlined.


title: Unveiling the Nature of the High Energy Source IGR J19140+0951

abstract:
  We report on high energy observations of IGR J19140+0951 performed with RXTE
on three occasions in 2002, 2003 and 2004, and INTEGRAL during a very well
sampled and unprecedented high energy coverage of this source from early-March
to mid-May 2003. Our analysis shows that IGR J19140+0951 spends most of its
time in a very low luminosity state, probably corresponding to the state
observed with RXTE, and characterised by thermal Comptonisation. In some
occasions we observe variations of the luminosity by a factor of about 10
during which the spectrum can show evidence for a thermal component, besides
thermal Comptonisation by a hotter plasma than during the low luminosity state.
The spectral parameters obtained from the spectral fits to the INTEGRAL and
RXTE data strongly suggest that IGR J19140+0951 hosts a neutron star rather
than a black hole. Very importantly, we observe variations of the absorption
column density (with a value as high as ~10^23 cm^-2). Our spectral analysis
also reveals a bright iron line detected with both RXTE/PCA and INTEGRAL/JEM-X,
at different levels of luminosity. We discuss these results and the behaviour
of IGR J19140+0951, and show, by comparison with other well known systems (Vela
X-1, GX 301-2, 4U 2206+54), that IGR J19140+0951 is most probably a High Mass
X-ray Binary.


title: Braneworld flow equations

abstract:
  We generalize the flow equations approach to inflationary model building to
the Randall-Sundrum Type II braneworld scenario. As the flow equations are
quite insensitive to the expansion dynamics, we find results similar to, though
not identical to, those found in the standard cosmology.


title: A Concordance Model of the Lyman-alpha Forest at z = 1.95

abstract:
  We present 40 fully hydrodynamical numerical simulations of the intergalactic
gas that gives rise to the Ly-alpha forest. We make artificial spectra from
each and measure three output parameters: the mean flux, a measure of the most
common Ly-alpha line width (b-value), and the 1D power spectrum of the flux on
scales from 0.01 - 0.1 s/km. We investigate how these output parameters are
correlated with the input parameters that describe the simulations. These input
parameters include the main cosmological parameters; and two astrophysical
parameters gammah and gammahe. The parameter gammah controls the rate of
ionization of H I, He I and He II while gammahe controls the rate of heating.
We compare the output from the simulations to data from HIRES and UVES spectra
and we give a new measurement of the flux power from these spectra at z=1.95.
We find that simulations with a wide variety of sigma_8 values, from at least
0.8 - 1.1, can fit the small scale flux power and b-values when we adjust
gammahe to compensate for the sigma_8 change. We can also use gammah to adjust
the H I ionization rate to simultaneously match the mean flux. We derive
scaling relations that give the output parameter values expected for a variety
of input parameters with errors of 2% for optical depth and 1.4% for b-balues.
We can break the degeneracy between gammahe and sigma_8 using large scale power
or other data to fix sigma_8.


title: Hot, Dense Matter Accretion onto a Black Hole

abstract:
  The accretion of hot, dense matter which consists of heavy nuclei, free
nucleons, degenerated electrons, photons and neutrinos is studied. The
composition of free nucleons and their chemical potentials are provided through
the equation of state for hot, dense matter proposed by Lattimer and
Swesty(1991). When the mass of a central black hole and the accretion rate are
selected as $M_{BH} \approx 3{\rm M}_\odot$ and $\dot{M} \approx 0.1{\rm
M}_\odot$sec$^{-1}$, which provide the typical luminosity of gamma ray
bursts(GRBs), the fraction of free protons in the accreting matter becomes very
small, $Y_p \approx 10^{-4}$, while that of free neutrons is closer to unity,
$Y_n \approx 0.7$. Then the antielectron neutrinos $\bar{\nu}_e$ can freely
escape through the disk but the electron neutrinos $\nu_e$ are almost absorbed
in the disk. Thus the frequent collisions of $\bar{\nu}_e$ with $\nu_e$ over
the disk couldn't be occurred. The accretion disk is cooled mainly by
$\bar{\nu}_e$, which suppresses the increase of temperature and increases the
density in the accreting matter such as $T \approx 3\times 10^{10}$K and $\rho
\approx 3\times 10^{13}$g/cm$^3$ at the inner side of the disk. The scattering
optical depths of $\bar{\nu}_e$ and $\nu_e$ then reach to be very large,
$\tau_s(\bar{\nu}_e) \approx \tau_s({\nu}_e) \approx 10^2$. Thus the accretion
disk could be thermally unstable within the duration of diffusion time of
neutrinos, $t_{diff} \approx 10$(ms).


title: Density Diagnostics of the Hot Plasma in AE Aquarii with XMM-Newton

abstract:
  High resolution spectroscopy of AE Aquarii with the XMM-Newton RGS has
enabled us to measure the electron number density of the X-ray-emitting hot
plasma to be ~1E11/cm**-3 by means of intensity ratios of the He-like triplet
of Nitrogen and Oxygen. Incorporating with the emission measure evaluated by
the EPIC cameras, we have also found a linear scale of the plasma to be ~5E10
cm. Both these values, obtained model-independently, are incompatible with a
standard post-shock accretion column of a magnetized white dwarf, but are
naturally interpreted as the plasma being formed through interaction between an
accretion flow and the magnetosphere of the white dwarf. Our results provide
another piece of evidence of the magnetic propeller effect being at work in AE
Aqr.


title: Super-Massive Black Holes and Dark Halos

abstract:
  The relations between masses of Super-Massive Black Holes, Mbh, in galactic
nuclei, maximal rotational velocities, Vm, and indicative masses, Mi, of
galaxies are studied for galaxies with the available rotation curves. Mbh
correlates with both Vm and Mi, although much weaker than with the central
velocity dispersion S0. Masses Mbh for early-type galaxies (S0-Sab), which
usually possess more luminous bulges, are, on average, larger than those for
late-type galaxies with similar velocities of rotation. It enables to conclude
that masses of black holes are determined mainly by the bulge properties, and -
much weaker - by dark haloes of galaxies.


title:
Damped Lyman alpha Absorbing Galaxies At Low Redshifts z<1 From
  Hierarchical Galaxy Formation Models

abstract:
  We investigate Damped Ly-alpha absorbing galaxies (DLA galaxies) at low
redshifts z<1 in the hierarchical structure formation scenario to clarify the
nature of DLA galaxies because observational data of such galaxies mainly at
low redshifts are currently available. We find that our model well reproduces
distributions of fundamental properties of DLA galaxies such as luminosities,
column densities, impact parameters obtained by optical and near-infrared
imagings. Our results suggest that DLA systems primarily consist of low
luminosity galaxies with small impact parameters (typical radius about 3 kpc,
surface brightness from 22 to 27 mag arcsec^{-2}) similar to low surface
brightness (LSB) galaxies. In addition, we investigate selection biases arising
from the faintness and from the masking effect which prevents us from
identifying a DLA galaxy hidden or contaminated by a point spread function of a
background quasar. We find that the latter affects the distributions of DLA
properties more seriously rather than the former, and that the observational
data are well reproduced only when taking into account the masking effect. The
missing rate of DLA galaxies by the masking effect attains 60-90 % in the
sample at redshift 0<z<1 when an angular size limit is as small as 1 arcsec.
Furthermore we find a tight correlation between HI mass and cross section of
DLA galaxies, and also find that HI-rich galaxies with M(HI) \sim 10^{9} M_sun
dominate DLA systems. These features are entirely consistent with those from
the Arecibo Dual-Beam Survey which is a blind 21 cm survey. Finally we discuss
star formation rates, and find that they are typically about 10^{-2} M_sun
yr^{-1} as low as those in LSB galaxies.


title: Trans-sonic propeller stage

abstract:
  We follow the approach used by Davies and Pringle (1981) and discuss the
trans-sonic substage of the propeller regime. This substage is intermediate
between the supersonic and subsonic propeller substages. In the trans-sonic
regime an envelope around a magnetosphere of a neutron star passes through a
kind of a reorganization process. The envelope in this regime consists of two
parts. In the bottom one turbulent motions are subsonic. Then at some distance
$r_\mathrm{s}$ the turbulent velocity becomes equal to the sound velocity.
During this substage the boundary $r_\mathrm{s}$ propagates outwards till it
reaches the outer boundary, and so the subsonic regime starts.
  We found that the trans-sonic substage is unstable, so the transition between
supersonic and subsonic substages proceeds on the dynamical time scale. For
realistic parameters this time is in the range from weeks to years.


title:
The two sided parsec scale structure of the Low Luminosity Active
  Galactic Nucleus in NGC 4278

abstract:
  We present new Very Long Baseline Interferometry observations of the LINER
galaxy NGC 4278 with a linear resolution of < 0.1 pc. Our radio data reveal a
two sided structure, with symmetric S-shaped jets emerging from a flat spectrum
core. By comparing the positions of the components in two epochs, we measure
motions corresponding to apparent velocities < 0.2 c, and to ages in the range
8.3 - 65.8 years. From our measurements, we derive that NGC 4278 has mildly
relativistic jets (beta aprox 0.75), closely aligned to the line-of-sight (2
deg < theta < 4 deg). We also present a flux density history for the source
with data between 1972 and 2003. All these arguments indicates that the low
power radio emission from NGC 4278 is emitted via the synchrotron process by
relativistic particles accelerated by a supermassive black hole.


title: VLBI observations of weak sources using fast frequency switching

abstract:
  We have developed a new phase referencing technique for high frequency VLBI
observations. In conventional phase referencing, one interleaves short scans on
a nearby phase calibrator between the target source observations. In fast
frequency switching described here, one observes the target source continuously
while switching rapidly between the target frequency and a lower reference
frequency. We demonstrate that the technique allows phase calibration almost
reaching the thermal noise limit and present the first detection of the AGN in
the FR I radio galaxy NGC 4261 at 86 GHz. Although point-like, this is the
weakest source ever detected with VLBI at this frequency.


title: How to simulate the Universe in a Computer

abstract:
  In this contribution a broad overview of the methodologies of cosmological
N-body simulations and a short introduction explaining the general idea behind
such simulations is presented. After explaining how to set up the initial
conditions using a set of N particles two (diverse) techniques are presented
for evolving these particles forward in time under the influence of their
self-gravity. One technique (tree codes) is solely based upon a sophistication
of the direct particle-particle summation whereas the other method relies on
the continuous (de-)construction of arbitrarily shaped grids and is realized in
adaptive mesh refinement codes.


title: Tracing the Warm Hot Intergalactic Medium in the local Universe

abstract:
  We present a simple method for tracing the spatial distribution and
predicting the physical properties of the Warm-Hot Intergalactic Medium (WHIM),
from the map of galaxy light in the local universe. Under the assumption that
biasing is local and monotonic we map the ~ 2 Mpc/h smoothed density field of
galaxy light into the mass density field from which we infer the spatial
distribution of the WHIM in the local supercluster. Taking into account the
scatter in the WHIM density-temperature and density-metallicity relation,
extracted from the z=0 outputs of high-resolution and large box size
hydro-dynamical cosmological simulations, we are able to quantify the
probability of detecting WHIM signatures in the form of absorption features in
the X-ray spectra, along arbitrary directions in the sky. To illustrate the
usefulness of this semi-analytical method we focus on the WHIM properties in
the Virgo Cluster region.


title: Attenuation caused by a distant Isothermal Turbulent Screen

abstract:
  We analyse in detail the attenuation caused by an isothermal turbulent
distant foreground dust screen. The attenuation curve is well determined by two
parameters, the absolute-to-relative attenuation ratio R^A_V=A_V/E(B-V) and the
absolute attenuation A_V. We show quantitatively how these two observable
quantities depend on the statistical properties of the local density and the
mean attenuation <A_V> and how they vary with the thickness of the screen
measured in units of the largest turbulent scale. The attenuation through a
turbulent medium is characterised by higher transparency and a flatter
attenuation curve in comparison with a homogeneous dust screen. In general, the
effect of the turbulent medium on the attenuation increases with slice
thickness. In the limit of thick slices, typically larger than the maximum
turbulent scale, R^A_V asymptotically approaches a maximum value.


title:
Formation and evolution of compact binaries with an accreting white
  dwarf in globular clusters

abstract:
  The population of compact binaries in dense stellar systems is affected
strongly by frequent dynamical interactions between stars and their interplay
with the stellar evolution. In this contribution, we consider these effects on
binaries with a white dwarf accretor, in particular cataclysmic variables and
AM CVns. We examine which processes can successfully lead to the creation of
such X-ray binaries. Using numerical simulations, we identify predominant
formation channels and predict the expected numbers of detectable systems. We
discuss also why the distribution of cataclysmic variables has a weaker
dependence upon the cluster density than the distribution of quiescent low-mass
X-ray binaries and why dwarf nova outbursts may not occur among globular
cluster cataclysmic variables.


title: CMB Anisotropy of the Poincare Dodecahedron

abstract:
  We analyse the anisotropy of the cosmic microwave background (CMB) for the
Poincare dodecahedron which is an example for a multi-connected spherical
universe. We compare the temperature correlation function and the angular power
spectrum for the Poincare dodecahedral universe with the first-year WMAP data
and find that this multi-connected universe can explain the surprisingly low
CMB anisotropy on large scales found by WMAP provided that the total energy
density parameter Omega_tot is in the range 1.016...1.020. The ensemble average
over the primordial perturbations is assumed to be the scale-invariant
Harrison-Zel'dovich spectrum. The circles-in-the-sky signature is studied and
it is found that the signal of the six pairs of matched circles could be missed
by current analyses of CMB sky maps.


title: The Fundamental Plane of Cluster Ellipticals at z = 1.25

abstract:
  Using deep HST ACS imaging and VLT FORS2 spectra, we determined the velocity
dispersions, effective radii and surface brightnesses for four early-type
galaxies in the $z=1.237$ cluster \cl. All four galaxies are massive, $>
10^{11} M_{\sun}$. These four galaxies, combined with three from \lynx at
$z=1.276$, establish the Fundamental Plane of massive early-type cluster
galaxies at $\bar{z}=1.25$. The offset of the Fundamental Plane shows that the
luminosity evolution in rest-frame $B$ is $\Delta \ln M/L_B = (-0.98 \pm 0.06)
z$ for galaxies with $M > 10^{11.5} M_{\sun}$. To reproduce the observed
mass-to-light ratio ($M/L$) evolution, we determine the characteristic age of
the stars in these $M > 10^{11.5} M_{\sun}$ galaxies to be $3.0^{+0.3}_{-0.3}$
Gyrs, {\em i.e.} $z_{*}=3.4^{+0.5}_{-0.4}$. Including selection effects caused
by morphological bias (the ``progenitor bias''), we estimate an age of
$2.1^{+0.2}_{-0.2}$ Gyrs, or $z_{*} = 2.3^{+0.2}_{-0.2}$ for the elliptical
galaxy population. Massive cluster early-type galaxies appear to have a large
fraction of stars that formed early in the history of the universe. However,
there is a large scatter in the derived $M/L$ values, which is confirmed by the
spread in the galaxies' colors. Two lower mass galaxies in our $\bar{z}=1.25$
sample have much lower $M/L$ values, implying significant star-formation close
to the epoch of observation. Thus, even in the centers of massive clusters,
there appears to have been significant star formation in some massive, $M
\simeq 10^{11} M_{\sun}$, galaxies at $z\simeq 1.5$.


title:
Escape of Lyman alpha Emission in the Starburst Galaxy Mkn 357 - a
  Wind's Far Side

abstract:
  HST imaging and slitless spectroscopy are used to examine where the strong
Lyman alpha emission escapes from the interstellar medium in the starburst
galaxy Mkn 357. An H-alpha image shows that the ionized gas is mostly in a
global wind, rather than associated with the individual star-forming regions
seen in the optical and UV continuum. The Lyman alpha emission comes
predominantly from the northwest side of the wind structure spatially, and
shows a significant redshift relative to the optical lines. Both of these
properties are signatures of seeing the line photons backscattered from the far
side of a prolate or bipolar starburst wind, fitting both with escape
calculations and evidence for winds in high-redshift galaxies with net Lyman
alpha emission. Scattering is most important within this wind itself, rather
than involving a surrounding neutral medium, as shown by the decreasing
relative redshift of the line peak from 250 to 30 km/s between the center and
edge of the detected emission. The Lyman alpha emission exhibits strong
asymmetry in comparison with both the starlight and H-alpha structures. These
results add to the evidence that kinematics, rather than gas metallicity or
dust content, are the dominant effect in determining which galaxies have strong
Lyman alpha emission, and that powerful (and perhaps episodic) starbursts are
common among Lyman-break galaxies as well as those discovered from Lyman alpha
line emission.


title: Cosmic Ray Acceleration during Large Scale Structure Formation

abstract:
  Clusters of galaxies are storage rooms of cosmic rays. They confine the
hadronic component of cosmic rays over cosmological time scales due to
diffusion, and the electron component due to energy losses. Hadronic cosmic
rays can be accelerated during the process of structure formation, because of
the supersonic motion of gas in the potential wells created by dark matter. At
the shock waves that result from this motion, charged particles can be
energized through the first order Fermi process. After discussing the most
important evidences for non-thermal phenomena in large scale structures, we
describe in some detail the main issues related to the acceleration of
particles at these shock waves, emphasizing the possible role of the dynamical
backreaction of the accelerated particles on the plasmas involved.


title: A Redshift Survey of the Submillimeter Galaxy Population

abstract:
  We have obtained spectroscopic redshifts using the Keck-I telescope for a
sample of 73 submillimeter (submm) galaxies for which precise positions are
available. The galaxies lie at redshifts out to z=3.6, with a median redshift
of 2.2. The dust-corrected ultraviolet (UV) luminosities of the galaxies rarely
hint at their huge bolometric luminosities indicated by their radio/submm
emission, underestimating the true luminosity by a median factor of ~100 for
SMGs with pure starburst spectra. The 850mu, radio, and redshift data is used
to estimate the dust temperatures (<Td>=36+-7 K), and characterize photometric
redshifts. We calculate total infrared and bolometric luminosities, construct a
luminosity function, and quantify the strong evolution of the submm population
across z=0.5-3.5, relative to local IRAS galaxies. We conclude that bright
submm galaxies contribute a comparable star formation density to Lyman-break
galaxies at z=2-3 and including galaxies below our submm flux limit this
population may be the dominant site of massive star formation at this epoch.
The rapid evolution of submm galaxies and QSO populations contrasts with that
seen in bolometrically lower luminosity galaxy samples selected in the
restframe UV, and suggests a close link between submm galaxies and the
formation and evolution of the galactic halos which host QSOs. [Abridged].