title:
The Lyman-alpha forest opacity and the metagalactic hydrogen ionization
  rate at z~2-4

abstract:
  Estimates of the metagalactic hydrogen ionization rate from the Lyman-alpha
forest opacity in QSO absorption spectra depend on the complex density
distribution of neutral hydrogen along the line-of-sight. We use a large suite
of high resolution hydrodynamical simulations to investigate in detail the
dependence of such estimates on physical and numerical parameters in the
context of Lambda-CDM models. Adopting fiducial values for cosmological
parameters together with published values of the temperature of the IGM and the
effective optical depth, the metagalactic ionization rates which reproduce the
Lyman-alpha effective optical depth at z=[2,3,4] are Gamma_HI=[1.3\pm^0.8_0.5,
0.9\pm0.3, 1.0\pm^0.5_0.3] \times 10^-12 s^-1, respectively. The errors include
estimates of uncertainties in the relevant physical parameters and the
numerical accuracy of the simulations. We find the errors are dominated by the
uncertainty in the temperature of the low-density IGM. The estimated
metagalactic hydrogen ionization rate for the neutral hydrogen distribution in
the current concordance Lambda-CDM model is more than four times the value
inferred for that in an Einstein-de Sitter model of the same r.m.s. density
fluctuation amplitude sigma_8. The estimated ionization rate is also more than
double that expected from updated estimates of the emissivity of observed QSOs
alone. A substantial contribution from galaxies appears to be required at all
redshifts.


title:
Diameters of Mira Stars Measured Simultenously in the J,H,K'
  Near-Infrared Bands

abstract:
  We present the first spatially resolved observations of a sample of 23 Mira
stars simultaneously measured in the near-infrared J, H and K' bands. The
technique used was optical long baseline interferometry, and we present for
each star visibility amplitude measurements as a function of wavelength. We
also present characteristic sizes at each spectral band, obtained by fitting
the measured visibilities to a simple uniform disk model. This approach reveals
the general relation J diameter < H diameter < K' diameter.


title: Spurious contribution to CR scattering calculations

abstract:
  The quasilinear theory for cosmic ray propagation is a well known and widely
accepted theory. In this paper, we discuss the different contributions to the
pitch-angle Fokker-Planck coefficient from large and small scales for slab
geometry using the damping model of dynamical turbulence. These examinations
will give us a hint on the limitation range where quasilinear approximation is
a good approximation.


title:
The Red-Sequence Cluster Survey I: The Survey and Cluster Catalogs for
  Patches RCS0926+37 and RCS1327+29

abstract:
  The Red-Sequence Cluster Survey (RCS) is a $\sim$100 square degree,
two-filter imaging survey in the $R_C$ and $z'$ filters, designed primarily to
locate and characterise galaxy clusters to redshifts as high as $z=1.4$. This
paper provides a detailed description of the survey strategy and execution,
including a thorough discussion of the photometric and astrometric calibration
of the survey data. The data are shown to be calibrated to a typical
photometric uncertainty of 0.03-0.05 magnitudes, with total astrometric
uncertainties less than 0.25 arcseconds for most objects. We also provide a
detailed discussion of the adaptation of a previously described cluster search
algorithm (the cluster red-sequence method) to the vagaries of real survey
data, with particular attention to techniques for accounting for subtle
variations in survey depths caused by changes in seeing and sky brightness and
transparency. A first catalog of RCS clusters is also presented, for the survey
patches RCS0926+37 and RCS1327+29. These catalogs, representing about 10% of
the total survey and comprising a total of 429 candidate clusters and groups,
contain a total of 67 cluster candidates at a photometric redshift of
$0.9<z<1.4$, down to the chosen significance threshold of 3.29$\sigma$.


title:
Confronting cosmological simulations with observations of intergalactic
  metals

abstract:
  Using the statistics of pixel optical depths, we compare HI, CIV and CIII
absorption in a set of six high quality z ~ 3-4 quasar absorption spectra to
that in spectra drawn from two different state-of-the-art cosmological
simulations that include galactic outflows. We find that the simulations
predict far too little CIV absorption unless the UVB is extremely soft, and
always predict far too small CIII/CIV ratios. We note, however, that much of
the enriched gas is in a phase (T ~ 10^5-10^7 K, overdensity ~ 0.1-10, Z >~0.1
Z_sol) that should cool by metal line emission -- which was not included in our
simulations. When the effect of cooling is modeled, the predicted CIV
absorption increases substantially, but the CIII/CIV ratios are still far too
small because the density of the enriched gas is too low. Finally, we find that
the predicted metal distribution is much too inhomogeneous to reproduce the
observed probability distribution of CIV absorption. These findings suggest
that strong z <~ 6 winds cannot fully explain the observed enrichment, and that
an additional (perhaps higher-z) contribution is required.


title: Eighth-Order Image Masks for Terrestrial Planet Finding

abstract:
  We describe a new series of band-limited image masks for coronagraphy that
are insensitive to pointing errors and other low-spatial-frequency optical
aberrations. For a modest cost in throughput, these ``eighth-order'' masks
would allow the Terrestrial Planet Finder Coronagraph (TPF-C) to operate with a
pointing accuracy no better than that of the Hubble Space Telescope. We also
provide eighth-order notch filter masks that offer the same robustness to
pointing errors combined with more manageable construction tolerances: binary
masks and graded masks with moderate optical density requirements.


title:
Using globular clusters to test gravity in the weak acceleration regime:
  NGC 6171

abstract:
  As part of an ongoing program to test Newton's law of gravity in the low
acceleration regime using globular clusters, we present here new results
obtained for NGC 6171. Combining VLT spectra for 107 stars with data from the
literature, we were able to trace the velocity dispersion profile up to 16 pc
from the cluster center, probing accelerations of gravity down to 3.5e-9
cm/s/s. The velocity dispersion is found to remain constant at large radii
rather than follow the Keplerian falloff. Similar results were previously found
for the globular clusters $\omega$ Centauri and M15. We have now studied three
clusters and all three have been found to have a flat dispersion profile beyond
the radius where their internal acceleration of gravity is ~ 1e-8 cm/s/s.
Whether this indicates a failure of Newtonian dynamics or some more
conventional dynamical effect (e.g., tidal heating) is still unclear. However,
the similarities emerging between globular clusters and elliptical galaxies
seem to favor the first of the two possibilities.


title:
Modeling the evolution of infrared luminous galaxies: the influence of
  the Luminosity-Temperature distribution

abstract:
  The evolution of the luminous infrared galaxy population is explored using a
pure luminosity evolution model which incorporates the locally observed
luminosity-temperature distribution for IRAS galaxies. Pure luminosity
evolution models in a fixed $\Lambda$CDM cosmology are fitted to submillimeter
(submm) and infrared counts, and backgrounds. It is found that the differences
between the locally determined bivariate model and the single variable
luminosity function (LF) do not manifest themselves in the observed counts, but
rather are primarily apparent in the dust temperatures of sources in flux
limited surveys. Statistically significant differences in the redshift
distributions are also observed. The bivariate model is used to predict the
counts, redshifts and temperature distributions of galaxies detectable by {\it
Spitzer}. The best fitting model is compared to the high-redshift submm galaxy
population, revealing a median redshift for the total submm population of
$z=1.8^{+0.9}_{-0.4}$, in good agreement with recent spectroscopic studies of
submillimeter galaxies. The temperature distribution for the submm galaxies is
modeled to predict the radio/submm indices of the submm galaxies, revealing
that submm galaxies exhibit a broader spread in spectral energy distributions
than seen in the local IRAS galaxies.


title:
Dynamical Expansion of Ionization and Dissociation Front around a
  Massive Star. I. A Mode of Triggered Star Formation

abstract:
  We analyze the dynamical expansion of the HII region and outer
photodissociation region (PDR) around a massive star by solving the UV and FUV
radiation transfer and the thermal and chemical processes in a time-dependent
hydrodynamics code. We focus on the physical structure of the shell swept up by
the shock front (SF) preceding the ionization front (IF). After the IF reaches
the initial Stromgren radius, the SF emerges in front of the IF and the
geometrically thin shell bounded with the IF and the SF is formed. The gas
density inside the shell is about 10-100 times as high as the ambient gas
density. Initially the dissociation fronts expands faster than IF and the PDR
is formed outside the HII region. Thereafter the IF and SF gradually overtakes
the proceeding dissociation fronts (DFs), and eventually DFs are taken in the
shell. The chemical composition within the shell is initially atomic, but
hydrogen and carbon monoxide molecules are gradually formed. This is partly
because the IF and SF overtake DFs and SF enters the molecular region, and
partly because the reformation timescales of the molecules become shorter than
the dynamical timescale. The gas shell becomes dominated by the molecular gas
by the time of gravitational fragmentation, which agrees with some recent
observations. A simple estimation of star formation rate in the shell can
provide a significant star formation rate in our galaxy.


title: The supermassive black hole in the Seyfert 2 galaxy NGC 5252

abstract:
  We present results from HST/STIS long-slit spectroscopy of the gas motions in
the nuclear region of the Seyfert 2 galaxy NGC 5252. The observed velocity
field is consistent with gas in regular rotation with superposed localized
patches of disturbed gas. The dynamics of the circumnuclear gas can be
accurately reproduced by adding to the stellar mass component a compact dark
mass of MBH = 0.95 (-0.45;+1.45) 10E9 M(sun), very likely a supermassive black
hole. Contrarily to results obtained in similar studies rotational broadening
is sufficient to reproduce also the behaviour of line widths. The MBH estimated
for NGC 5252 is in good agreement with the correlation between MBH and bulge
mass. The comparison with the MBH vs sigma relationship is less stringent
(mostly due to the relatively large error in sigma); NGC 5252 is located above
the best fit line by between 0.3 and 1.2 dex, i.e. 1 - 4 times the dispersion
of the correlation. Both the galaxy's and MBH of NGC 5252 are substantially
larger than those usually estimated for Seyfert galaxies but, on the other
hand, they are typical of radio-quiet quasars. Combining the determined MBH
with the hard X-ray luminosity, we estimate that NGC 5252 is emitting at a
fraction ~ 0.005 of L(Edd). In this sense, this active nucleus appears to be a
quasar relic, now probably accreting at a low rate, rather than a low black
hole mass counterpart of a QSO.


title:
Various applications of multicolour photometry and radial velocity data
  for multimode $\delta$ Scuti stars

abstract:
  In addition to revealing spherical harmonic degrees, $\ell$, of excited
modes, pulsational amplitudes and phases from multicolour photometry and radial
velocity data yield a valuable constraints on stellar atmospheric parameters
and on subphotospheric convection. Multiperiodic pulsators are of particular
interest because each mode yields independent constraints. We present an
analysis of data on twelve modes observed in FG Vir star.


title: Galactic Supernova Remnants: an Updated Catalogue and Some Statistics

abstract:
  A catalogue of 231 Galactic supernova remnants (SNRs) is presented, and the
selection effects applicable to the identification of remnants at radio
wavelengths are discussed. In addition to missing low surface brightness
remnants, small angular size -- i.e. young but distant -- remnants are also
missing from the current catalogue of Galactic SNRs. Several statistical
properties of Galactic SNRs are discussed, including the
surface-brightness/diameter (Sigma-D) relation. It is concluded that the wide
range of intrinsic properties of Galactic remnants with known distances,
together with the observational selection effects, means that use of the
Sigma-D relation to derive diameters and hence distances for individual SNRs,
or for statistical studies, is highly uncertain. The observed distribution of
bright SNRs, which are thought to be largely free from selection effects, is
also used to derive a simple model for the distribution of SNRs with
Galactocentric radius.


title:
The Origin of the Initial Mass Function and Its Dependence on the Mean
  Jeans Mass in Molecular Clouds

abstract:
  We investigate the dependence of stellar properties on the mean thermal Jeans
mass in molecular clouds. We compare the results from the two largest
hydrodynamical simulations of star formation to resolve the fragmentation
process down to the opacity limit, the first of which was reported by Bate,
Bonnell & Bromm. The initial conditions of the two calculations are identical
except for the radii of the clouds, which are chosen so that the mean densities
and mean thermal Jeans masses of the clouds differ by factors of nine and
three, respectively. We find that the denser cloud, with the lower mean thermal
Jeans mass, produces a higher proportion of brown dwarfs and has a lower
characteristic (median) mass of the stars and brown dwarfs. This dependence of
the initial mass function (IMF) on the density of the cloud may explain the
observation that the Taurus star-forming region appears to be deficient in
brown dwarfs when compared with the Orion Trapezium cluster. The new
calculation also produces wide binaries (separations >20 AU), one of which is a
wide binary brown dwarf system. Based on the hydrodynamical calculations, we
develop a simple accretion/ejection model for the origin of the IMF. In the
model, all stars and brown dwarfs begin with the same mass (set by the opacity
limit for fragmentation) and grow in mass until their accretion is terminated
stochastically by their ejection from the cloud through dynamically
interactions. The model predicts that the main variation of the IMF in
different star-forming environments should be in the location of the peak (due
to variations in the mean thermal Jeans mass of the cloud) and in the
substellar regime. However, the slope of the IMF at high-masses may depend on
the dispersion in the accretion rates of protostars.


title: Atomic carbon in PSS 2322+1944, a quasar at redshift 4.12

abstract:
  We report the detection of the 3P1 to 3P0 fine-structure line of neutral
carbon in the z=4.12 quasar PSS 2322+1944, obtained at the IRAM Plateau de Bure
interferometer. The CI 3P1-3P0 line is detected with a signal-to-noise ratio of
about 6 with a peak intensity of about 2.5 mJy and a velocity-integrated line
flux of 0.81+-0.12 Jy.km/s. Assuming an excitation temperature of 43 K (equal
to the dust temperature), we derive a mass of neutral carbon (corrected for
magnification) of about 1.2e7 Msun. In PSS 2322+1944, the cooling due to C is
about 6 times smaller than for CO, whereas the CO and C cooling represents
about 1e-4 of the far-infrared continuum and more than half of the cooling due
to C+.


title:
Radiative feedback from quasars and the growth of massive black holes in
  stellar spheroids

abstract:
  We discuss the importance of feedback via photoionization and Compton heating
on the co-evolution of massive black holes (MBHs) at the center of spheroidal
galaxies and their stellar and gaseous components. We first assess the
energetics of the radiative feedback from a typical quasar on the ambient
interstellar medium. We then demonstrate that the observed Mbh-sigma relation
could be established following the conversion of most of the gas of an
elliptical progenitor into stars, specifically when the gas-to-stars mass ratio
in the central regions has dropped to a low level ~0.01 or less, so that gas
cooling is no longer able to keep up with the radiative heating by the growing
central MBH. A considerable amount of the remaining gas will be expelled and
both MBH accretion and star formation will proceed at significantly reduced
rates thereafter, in agreement with observations of present day ellipticals. We
find further support for this scenario by evolving over an equivalent Hubble
time a simple, physically based toy model that additionally takes into account
the mass and energy return for the spheroid evolving stellar population, a
physical ingredient often neglected in similar approaches.


title: Kinetic Luminosity and Composition of Active Galactic Nuclei Jets

abstract:
  We present a new method how to discriminate the matter content of
parsec-scale jets of active galactic nuclei. By constraining the kinetic
luminosity of a jet from the observed core size at a single very long baseline
interferometry frequency, we can infer the electron density of a radio-emitting
component as a function of the composition. Comparing this density with that
obtained from the theory of synchrotron self-absorption, we can determine the
composition. We apply this procedure to the five components in the 3C~345 jet
and find that they are likely pair-plasma dominated at 11 epochs out of the
total 21 epochs, provided that the bulk Lorentz factor is less than 15
throughout the jet. We also investigate the composition of the 3C~279 jet and
demonstrate that its two components are likely pair-plasma dominated at three
epochs out of four epochs, provided that their Doppler factors are less than
10, which are consistent with observations. The conclusions do not depend on
the lower cutoff energy of radiating particles.


title: Mass transfer in tidally unstable compact binaries

abstract:
  The 2001 outburst of WZ Sagittae has shown the most compelling evidence yet
for an enhancement of the mass transfer rate from the donor star during a dwarf
nova outburst in the form of hot-spot brightening. I show that even in this
extreme case, the brightening can be attributed to tidal heating near the
interaction point of an accretion stream with the expanding edge of an
eccentric accretion disc, with no need at all for an increase in the mass
transfer rate. Furthermore, I confirm previous suggestions that an increase in
mass transfer rate through the stream damps any eccentricity in an accretion
disc and suppresses the appearance of superhumps, in contradiction to
observations. Tidal heating is expected to be most significant in systems with
small mass ratios. It follows that systems like WZ Sagittae - which has a tiny
mass ratio - are those most likely to show a brightening in the hot-spot
region.


title: A Uniform CO Survey of the Molecular Clouds in Orion and Monoceros

abstract:
  We report the results of a new large scale survey of the Orion-Monoceros
complex of molecular clouds made in the J = 1->0 line of CO with the
Harvard-Smithsonian 1.2m millimetre-wave telescope. The survey consists of
52,288 uniformly spaced spectra that cover an area of 432 square degrees on the
sky and is the most sensitive large-scale survey of the region to date.
Distances to the constituent molecular clouds of the complex, estimated from an
analysis of foreground and background stars, have provided information on the
three dimensional structure of the entire complex.


title: Quantifying the Cosmic Web in the New Era of Redshift Surveys

abstract:
  Two main strategies have been implemented in mapping the local universe:
whole-sky 'shallow' surveys and 'deep' surveys over limited parts of the sky.
The two approaches complement each other in studying cosmography and
statistical properties of the Universe. We summarise some results on the power
spectrum of fluctuations and Wiener reconstruction of the density field from
the 2dF Galaxy Redshift Survey (2dFGRS) of 230,000 redshifts. We then discuss
future challenges in quantifying the web of cosmic structure in the on-going
redshift surveys.


title: White Dwarfs and Hot Subdwarfs as Seen from FUSE

abstract:
  We present a small collection of FUSE spectra representative of the main
spectral classes found in white dwarf stars. In addition, we also discuss
another family of hot evolved stars, that of the hot subdwarfs. Both families
belong to the chemically peculiar stars, and it is thought that a complex
interplay of competing processes such as gravitational settling, ordinary
diffusion, radiative levitation, weak stellar winds, and accretion is
responsible for the rich variety of atmospheric compositions observed in those
objects. FUSE is playing a key role in the current quest for establishing a
coherent theory of the spectral evolution of these stars as it allows the
determination of the patterns of heavy element abundances at a significantly
higher level of accuracy than has been possible before on the basis of optical
or UV observations. We also briefly present some fascinating FUV light curves
of a handful of pulsating subdwarf B stars, thus illustrating the unique
potential of FUSE for asteroseismological studies, a potential which has not
been exploited yet.


title: Weighing Neutrinos with Large-Scale Structure

abstract:
  While it is established that the effect of neutrinos on the evolution of
cosmic structure is small, the upper limits derived from large-scale structure
could help significantly to constrain the absolute scale of the neutrino
masses. Current results from cosmology set an upper limit on the sum of the
neutrino masses of ~ 1 eV, somewhat depending on the data sets used in the
analyses and assumed priors on cosmological parameters. In this review we
discuss the effects of neutrinos on large-scale structure which make these
limits obtainable. We show the impact of neutrino masses on the matter power
spectrum, the cosmic microwave background and the clustering amplitude. A
summary of derived cosmological neutrino mass upper limits is given, and we
discuss future methods which will improve the mass upper limits by an order of
magnitude.


title:
The Sedentary Survey of Extreme High Energy Peaked BL Lacs. II. The
  Catalog and Spectral Properties

abstract:
  The multi-frequency `Sedentary Survey' is a deep, statistically complete,
radio flux limited sample comprising 150 BL Lacertae objects distinguished by
their extremely high X-ray to radio flux ratio, ranging from five hundred to
over five thousand times that of typical BL Lacs discovered in radio surveys.
This paper presents the final, 100% identified, catalog together with the
optical, X-ray and broad-band SEDs constructed combining literature
multi-frequency data with non-simultaneous optical observations and BeppoSAX
X-ray data, when available. The SEDs confirm that the peak of the synchrotron
power in these objects is located at very high energies. BeppoSAX wide band
X-ray observations show that, in most cases, the X-ray spectra are convex and
well described by a logarithmic parabola model peaking (in a E f(E) vs E
representation) between 0.02 to several keV. Owing to the high synchrotron
energies involved most of the sources in the catalog are likely to be TeV
emitters, with the closest and brightest ones probably detectable by the
present generation of Cherenkov telescopes. The optical spectrum of about one
fourth of the sources is totally featureless. Because this implies that the
non-thermal emission must be well above that of the host galaxy, these objects
are likely to be the most powerful sources in the survey and therefore be
examples of the yet unreported high radio luminosity-high energy peaked BL
Lacs.


title: Balmer and Metal Absorption Feature Gradients in M32

abstract:
  Spectra from MDM Observatory are used to assess Lick/IDS feature strength
gradients inside the half-light radius of the compact Local Group elliptical
galaxy M32. All but a few (of 24 measured) indices show a statistically
significant gradient. Comparing with models, the index gradients indicate a
mean age and abundance gradient in the sense that the nucleus is a factor of
2.5 younger and a factor of 0.3 dex more metal-rich than at 1 effective radius.
This conclusion is only weakly dependent on which index combinations are used
and is robust to high accuracy. Stars near the M32 nucleus have a mean age and
heavy element abundance [M/H] of (4.7 Gyr, +0.02), judging from models by
Worthey with variable abundance ratios. This result has very small formal
random errors, although, of course, there is significant age-metallicity
degeneracy along an (age, abundance) line segment from (5.0 Gyr, 0.00) to (4.5
Gyr, +0.05). An abundance pattern of [C/M]=+0.077, [N/M]=-0.13, [Mg/M]=-0.18,
[Fe/M]~0.0, and [Na/M]=+0.12 is required to fit the feature data, with a
fitting precision of about 0.01 dex. Model uncertainties make the accuracies of
these values at least twice the magnitude of the precision. Forcing
scaled-solar abundances does not change the age very much, but it increases the
rms goodness of model-data fit by a factor of 3 and broadens the allowed range
of age to $\pm 1$ Gyr. The overall abundance pattern contrasts with larger
elliptical galaxies, in which all measurable lighter elements are enhanced
relative to iron and calcium.


title: Carbon Stars and other Luminous Stellar Populations in M33

abstract:
  The M33 galaxy is a nearby, relatively metal-poor, late-type spiral. Its
proximity and almost face-on inclination means that it projects over a large
area on the sky, making it an ideal candidate for wide-field CCD mosaic
imaging. Photometry was obtained for more than 10^6 stars covering a 74' x 56'
field centered on M33. Main sequence (MS), supergiant branch (SGB), red giant
branch (RGB) and asymptotic giant branch (AGB) populations are identified and
classified based on broad-band V and I photometry. Narrow-band filters are used
to measure spectral features allowing the AGB population to be further divided
into C and M-star types. The galactic structure of M33 is examined using star
counts, colour-colour and colour-magnitude selected stellar populations. We use
the C to M-star ratio to investigate the metallicity gradient in the disk of
M33. The C/M-star ratio is found to increase and then flatten with increasing
galactocentric radius in agreement with viscous disk formation models. The
C-star luminosity function is found to be similar to M31 and the SMC,
suggesting that C-stars should be useful distance indicators. The ``spectacular
arcs of carbon stars'' in M33 postulated recently by Block et al. (2004) are
found in our work to be simply an extension of M33's disk.


title:
Expansion of radio galaxies in a cosmologically evolving medium:
  Possible implications for the cosmic star-formation history

abstract:
  We compare earlier estimates of the volumes filled by lobes of radio galaxies
during the quasar era based upon non-evolving ambient media with new ones
assuming a strong cosmological evolution of the ambient medium. If the sources
remain active for over 10^8 years the volumes filled by them are found to be
comparable for the two scenarios. This strengthens our earlier inference that
much of the cosmic web of gaseous filaments, the site of galaxy formation, was
probably permeated by radio lobes during the quasar era and this could have
triggered extensive star formation and made large contributions to the spread
of magnetic fields and metals through the universe by z ~ 2.


title:
The apparent shape of the "Str\"omgren sphere'' around the
  highest-redshift QSOs with Gunn-Peterson troughs

abstract:
  Although the highest redshift QSOs (z>6.1) are embedded in a significantly
neutral background universe (mass-averaged neutral hydrogen fraction >1%) as
suggested by the Gunn-Peterson absorption troughs in their spectra, the
intergalactic medium in their vicinity is highly ionized. The highly ionized
region is generally idealized as spherical and called the Str\"omgren sphere.
In this paper, by combining the expected evolution of the Str\"omgren sphere
with the rule that the speed of light is finite, we illustrate the apparent
shape of the ionization fronts around the highest redshift QSOs and its
evolution, which depends on the age, luminosity evolution, and environment of
the QSO (e.g., the hydrogen reionization history). The apparent shape may
systematically deviate from a spherical shape, unless the QSO age is
significantly long compared to the hydrogen recombination process within the
ionization front and the QSO luminosity evolution is significantly slow.
Effects of anisotropy of QSO emission are also discussed. The apparent shape of
the "Str\"omgren sphere'' may be directly mapped by transmitted spectra of
background sources behind or inside the ionized regions or by surveys of the
hyperfine transition (21cm) line emission of neutral hydrogen.


title:
The Str\"omgren sphere, the environment and the reionization in the
  local universe of the highest redshift QSOs

abstract:
  In this paper we investigate the environment and reionization process around
the highest redshift QSOs having Gunn-Peterson troughs (z>6.1). Starting with
the cosmic density perturbation and structure formation theory and the fact
that the highest redshift QSOs are located in rare overdense regions, we show
that the halo formation, gas distribution, and star formation around QSOs are
biased from those of the cosmic average. We argue that a significant fraction
of hydrogen in the Str\"omgren sphere around QSOs is ionized by photons from
stars and that only about several percent to at most 10%--20% of the total
hydrogen is left (e.g., in minihalos, halos, or high-density subregions) to be
ionized by QSO photons. The cosmic average neutral hydrogen fraction at
z~6.2-6.4 should also be smaller than the upper limit of 10%--20% and may be
only a few percent. We analyze the clumping property of the hydrogen ionized by
QSOs and study the evolution of the Str\"omgren sphere. We find that the
expected Str\"omgren radii from our models are consistent with observations if
the lifetime of the highest redshift QSOs is about or longer than a few times
10^7 yr (as is the lifetime of the main population of QSOs; with comoving
number density peaked at z~2-3). With such a QSO lifetime, the ages of most of
the observed QSOs are long enough that the QSO photon emission is balanced by
the recombination of the hydrogen ionized by QSO photons in their Str\"omgren
spheres, and the expected Str\"omgren radii from the balance are independent of
the detailed values of the QSO ages. (abridged)


title: Host Galaxy Evolution in Radio-Loud AGN

abstract:
  We investigate the luminosity evolution of the host galaxies of radio-loud
AGN through Hubble Space Telescope imaging of 72 BL Lac objects, including new
STIS imaging of nine z > 0.6 BL Lacs. With their intrinsically low accretion
rates and their strongly beamed jets, BL Lacs provide a unique opportunity to
probe host galaxy evolution independent of the biases and ambiguities implicit
in quasar studies. We find that the host galaxies of BL Lacs evolve strongly,
consistent with passive evolution from a period of active star formation in the
range 0.5 <~ z <~ 2.5, and inconsistent with either passive evolution from a
high formation redshift or a non-evolving population. This evolution is broadly
consistent with that observed in the hosts of other radio-loud AGN, and
inconsistent with the flatter luminosity evolution of quiescent early types and
radio-quiet hosts. This indicates that active star formation, and hence galaxy
interactions, are associated with the formation for radio-loud AGN, and that
these host galaxies preferentially accrete less material after their formation
epoch than galaxies without powerful radio jets. We discuss possible
explanations for the link between merger history and the incidence of a radio
jet.


title:
Group, field and isolated early-type galaxies I. Observations and
  nuclear data

abstract:
  This is the first paper of a series on the investigation of stellar
population properties and galaxy evolution of an observationally homogeneous
sample of early-type galaxies in groups, field and isolated galaxies. We
present high S/N long-slit spectroscopy of 86 nearby elliptical and S0
galaxies. 8 of them are isolated, selected according to a rigorous criterion.
This survey has the advantage of covering a larger wavelength range than
normally found in the literature, including [OIII]5007 and Halpha, both
important for emission correction. Among the 86 galaxies with S/N>15 (per
resolution element, for r_e/8 central aperture), 57 have their Hbeta-index
corrected for emission, average correction is 0.190A in Hbeta; 42 galaxies
reveal [OIII]5007 emission, of which 16 also show obvious Halpha emission. Most
of the galaxies in the sample do not show obvious signs of disturbances nor
tidal features in the morphologies, although 11 belong to the Arp catalogue of
peculiar galaxies; only 3 of them (NGC750, NGC751, NGC3226) seem to be strongly
interacting. We present the measurement of 25 central line-strength indices
calibrated to the Lick/IDS system. Kinematic information is obtained for the
sample. We analyse the line-strength index vs velocity dispersion relations for
our sample of mainly low density environment galaxies, and compare the slope of
the relations with cluster galaxies from the literature. Our main findings are
that the index-sigma_0 relations presented for low-density regions are not
significantly different from those of cluster E/S0s. The slope of the
index-sigma_0 relations does not seem to change for early-type galaxies of
different environmental densities, but the scatter of the relations seems
larger for group, field and isolated galaxies than for cluster galaxies.


title: Filamentary jets as a cosmic-ray "Zevatron"

abstract:
  Strong, anisotropic turbulence reflecting magnetized filaments is considered,
to model the diffusive acceleration of particles by shock waves in active
galactic nucleus jets. We address that at knot A of the nearby M87 jet, the
shock involving the filamentary turbulence can accelerate an iron nucleus to
zetta-eV (ZeV; 10^{21} eV) ranges. A smaller value of the particle diffusion
coefficient is found to be essential to achieve a ZeV cosmic-ray accelerator, a
"Zevatron."


title: A Comprehensive Approach to Resolving the Nature of the Dark Energy

abstract:
  A data-driven approach to elucidating the nature of the dark energy, in the
form of a joint analysis of a full set of cosmological parameters, utilizing
all available observational data is proposed. A parameterization of a
generalized dark energy is developed with the extension of fluid perturbation
theory to models which cross through an equation of state of -1. This
parameterization is selected to be general enough to admit a wide variety of
behavior, while still being physical and economical. A Fisher matrix analysis
with future high-precision CMB, cluster survey, and SNIa data suggests the
parameters will probably be resolvable in the foreseeable future. How
accurately the parameters can be determined depends sensitively on the nature
of the dark energy - particularly how significant of a fraction of the total
energy density it has been in the past. Parameter space will be sampled at a
large number of points, with cosmological information such as CMB, power
spectra, etc of each point being archived. Thus the likelihood functions of an
arbitrary set of experiments can be applied to parameter space with
insignificant new computational cost, making a wide variety of analyses
possible. The resulting tool for Analysis and Resolution of Dark-sector
Attributes, ARDA, will be highly versatile and adaptable. ARDA will allow the
scientific community to extract parameters with an arbitrary set of experiments
and theoretical priors, test for tension between classes of observations and
investigate the effectiveness of hypothetical experiments, while evolving in a
data-driven manner. A proof-of-concept prototype web-tool, \underbar{The Cosmic
Concordance Project}, is already available.


title:
Neutron Stars with a Quark Core. II.Basic Integral and Structural
  parameters

abstract:
  A broad sample of computed realistic equations of state of superdense matter
with quark phase transition is used to construct a series of models neutron
stars with a strange quark core. The integral characteristics of the stellar
configurations are obtained: gravitational mass, rest mass, radius,
relativistic moment of inertia, and red shift from the star's surface, as well
as the mass and radius of the quark core within the allowable range of the
central pressure. The parameters of some of the characteristic configurations
of the calculated series are also given and these are studied in detail. It is
found that a new additional region of stability for neutron stars with strange
quark cores may exist for some models of the equation of state.


title:
The Deep2 Galaxy Redshift Survey: Evolution of Close Galaxy Pairs and
  Major-Merger Rates Up to z ~ 1.2

abstract:
  We derive the close, kinematic pair fraction and merger rate up to z ~ 1.2
from the initial data of the DEEP2 Redshift Survey. Assuming a mild luminosity
evolution, the number of companions per luminous galaxy is found to evolve as
(1+z)^{m}, with m = 0.51+-0.28; assuming no evolution, m = 1.60+-0.29. Our
results imply that only 9% of present-day $L^{*}$ galaxies have undergone major
mergers since z ~ 1.2 and that the average major merger rate is about 4*
10^{-4} h^{3} Mpc^{-3} Gyr^{-1} for z ~ 0.5 - 1.2. Most previous studies have
yielded higher values.


title: Morphological and Luminosity Content of Poor Galaxy Groups

abstract:
  We find that the fraction of early-type galaxies in poor groups (containing
from 4 to 10 members) is a weakly increasing function of the number of the
group members and is about two times higher than in a sample of isolated
galaxies. We also find that the group velocity dispersion increases weakly with
the fraction of early-type galaxies. Early-type galaxies in poor groups are
brighter in the near-infrared with respect to isolated ones by 0.75 mags (in K)
and to a lesser degree (by 0.5 mags) also in the blue. We also find early-type
galaxies in groups to be redder than those in the field. These findings suggest
that the formation history for early-type galaxies in overdense regions is
different from that of in underdense regions, and that their formation in
groups is triggered by merging processes.


title: Extragalactic Gamma--Rays: Gamma Ray Bursts and Blazars

abstract:
  The extragalactic gamma-ray sky is dominated by two classes of sources:
Gamma-Ray Bursts (GRBs) and radio loud active galactic nuclei whose jets are
pointing at us (blazars). We believe that the radiation we receive from them
originates from the transformation of bulk relativistic energy into random
energy. Although the mechanisms to produce, collimate and accelerate the jets
in these sources are uncertain, it is fruitful to compare the characteristics
of both classes of sources in search of enlightening similarities. I will
review some general characteristics of radio loud AGNs and GRBs and I will
discuss the possibility that both classes of sources can work in the same way.
Finally, I will discuss some recent exciting prospects to use blazars to put
contraints on the cosmic IR-Optical-UV backgrounds, and to use GRBs as standard
candles to measure the Universe.


title: The central density cusp of the Sagittarius dwarf spheroidal galaxy

abstract:
  We present an analysis of the density profile in the central region of the
Sagittarius dwarf spheroidal galaxy. A strong density enhancement of Sgr stars
is observed. The position of the peak of the detected cusp is indistinguishable
from the center of M54. The photometric properties of the cusp are fully
compatible with those observed in the nuclei of dwarf elliptical galaxies,
indicating that the Sgr dSph would appear as a nucleated galaxy independently
of the presence of M54 at its center.


title: Modeling feedback from stars and black holes in galaxy mergers

abstract:
  We describe techniques for incorporating feedback from star formation and
black hole accretion into simulations of isolated and merging galaxies. At
present, the details of these processes cannot be resolved in simulations on
galactic scales. Our basic approach therefore involves forming coarse-grained
representations of the properties of the interstellar medium and black hole
accretion starting from basic physical assumptions, so that the impact of these
effects can be included on resolved scales. We illustrate our method using a
multiphase description of star-forming gas. Feedback from star formation
pressurises highly overdense gas, altering its effective equation of state. We
show that this allows the construction of stable galaxy models with much larger
gas fractions than possible in earlier numerical work. We extend the model by
including a treatment of gas accretion onto central supermassive black holes in
galaxies. Assuming thermal coupling of a small fraction of the bolometric
luminosity of accreting black holes to the surrounding gas, we show how this
feedback regulates the growth of black holes. In gas-rich mergers of galaxies,
we observe a complex interplay between starbursts and central AGN activity when
the tidal interaction triggers intense nuclear inflows of gas. Once an
accreting supermassive black hole has grown to a critical size, feedback
terminates its further growth, and expels gas from the central region in a
powerful quasar-driven wind. Our simulation methodology is therefore able to
address the coupled processes of gas dynamics, star formation, and black hole
accretion during the formation of galaxies.


title:
Upper Limits on Central Black Hole Masses of Globular Clusters from
  Radio Emission and a Possible Black Hole Detection in the Ursa Minor Dwarf
  Galaxy

abstract:
  Intermediate mass black holes have been alternatively predicted to be quite
common in the centers of globular clusters or nearly impossible to form and
retain in the centers of globular clusters. As it has been recently shown that
radio observations are currently the most sensitive observational technique for
detecting such objects, we have obtained new deep radio observations of Omega
Cen, and have re-analyzed older observations of M~15 in hope of constraining
the masses of possible black holes in their centers. In both cases, upper
limits of about 100 $\mu$Jy are found at GHz frequencies. We find that if the
Bondi-Hoyle accretion rate truly represents the spherical accretion rate onto a
black hole, then the masses of the black holes in the centers of these two
galaxies are severely constrained - with mass limits of less than about 100
solar masses in both cases. If more realistic assumptions are made based on
recent work showing the Bondi rate to be a severe overestimate, then the data
for Omega Cen are marginally consistent with a black hole of about 1/1000 the
cluster's mass (i.e. about 1000 $M_\odot$). The data for M~15 then are only
marginally consistent with previous reports of a $\sim2000$ solar mass black
hole, and we note that there is considerable hope for either detecting the
black hole or improving this upper limit with current instrumentation. Finally,
we discuss the possibility that the radio source near the core of the Ursa
Minor dwarf spheroidal galaxy is a $\sim10^4$ $M_\odot$ black hole.


title:
An atomic and molecular database for analysis of submillimetre line
  observations

abstract:
  Atomic and molecular data for the transitions of a number of astrophysically
interesting species are summarized, including energy levels, statistical
weights, Einstein A-coefficients and collisional rate coefficients. Available
collisional data from quantum chemical calculations and experiments are
extrapolated to higher energies. These data, which are made publically
available through the WWW at http://www.strw.leidenuniv.nl/~moldata, are
essential input for non-LTE line radiative transfer programs. An online version
of a computer program for performing statistical equilibrium calculations is
also made available as part of the database. Comparisons of calculated emission
lines using different sets of collisional rate coefficients are presented. This
database should form an important tool in analyzing observations from current
and future (sub)millimetre and infrared telescopes.


title: Pre-main-sequence Lithium Depletion

abstract:
  In this review I briefly discuss the theory of pre-main-sequence (PMS) Li
depletion in low-mass (0.075<M<1.2 Msun) stars and highlight those uncertain
parameters which lead to substantial differences in model predictions. I then
summarise observations of PMS stars in very young open clusters, clusters that
have just reached the ZAMS and briefly highlight recent developments in the
observation of Li in very low-mass PMS stars.


title:
The Lithium Depletion Boundary in NGC 2547 as a test of
  pre-main-sequence evolutionary models

abstract:
  Intermediate resolution spectroscopy from the ESO Very Large Telescope is
analysed for 63 photometrically selected low-mass (0.08-0.30 Msun) candidates
of the open cluster NGC 2547. We have confirmed membership for most of these
stars using radial velocities, and found that lithium remains undepleted for
cluster stars with I>17.54+/-0.14 and K_{s}>14.86+/-0.12. From these results,
several pre-main-sequence evolutionary models give almost model independent
ages of 34-36 Myr, with a precision of 10 per cent. These ages are only
slightly larger than the ages of 25-35 (+/-5) Myr obtained using the same
models to fit isochrones to higher mass stars descending towards the zero age
main sequence (ZAMS), both in empirically calibrated and theoretical
colour-magnitude diagrams. This agreement between age determinations in
different mass ranges is an excellent test of the current generation of
low-mass pre-main sequence stellar models and lends confidence to ages
determined with either method between 30 and 120 Myr.


title: Ultra High Energy Cosmic Rays

abstract:
  We discuss theoretical issues and experimental data that brought the ultra
high energy cosmic rays in the list of Nature's greatest puzzles.
  After many years of research we still do not know how astrophysical
acceleration processes can reach energies exceeding 10$^{11}$ GeV.
  The main alternative {\em top-down} mechanism postulates the existence of
super massive $X$-particles that create a particle spectrum extending down to
the observed energy through their decay channels.
  The propagation of nuclei and photons from their sources to us adds to the
puzzle as all particles of these energies interact with the ambient photons,
mostly of the microwave background.
  We also describe briefly the main observational results and give some
information on the new experiments that are being built and designed now.


title:
Higher Order Curvature Theories of Gravity Matched with Observations: a
  Bridge Between Dark Energy and Dark Matter Problems

abstract:
  Higher order curvature gravity has recently received a lot of attention due
to the fact that it gives rise to cosmological models which seem capable of
solving dark energy and quintessence issues without using "ad hoc" scalar
fields. Such an approach is naturally related to fundamental theories of
quantum gravity which predict higher order terms for loop expansions of quantum
fields in curved spacetimes. In this framework, we obtain a class of
cosmological solutions which are fitted against cosmological data. We reproduce
reliable models able to fit high redshift supernovae and WMAP observations. The
age of the universe and other cosmological parameters are recovered in this
context. Furthermore, in the weak field limit, we obtain gravitational
potentials which differ from the Newtonian one because of repulsive corrections
increasing with distance. We evaluate the rotation curve of our Galaxy and
compare it with the observed data in order to test the viability of these
theories and to estimate the scale-length of the correction. It is remarkable
that the Milky Way rotation curve is well fitted without the need of any dark
matter halo and similar results hold also for other galaxies.


title:
Radio Recombination Lines from Starbursts: NGC 3256, NGC 4945 and the
  Circinus Galaxy

abstract:
  A renewed attempt to detect radio recombination lines from external galaxies
has resulted in the measurement of lines from several bright starburst
galaxies. The lines are produced by hydrogen ionized by young, high-mass stars
and are diagnostic of the conditions and gas dynamics in the starburst regions
without problems of dust obscuration. We present here detections of the lines
H91alpha and H92alpha near 8.6 GHz from the starburst nuclei in NGC 3256, NGC
4945, and the Circinus galaxy using the ATCA and VLA. Modelling the line
emitting region as a collection of H II regions, we derive the required number
of H II regions, their temperature, density, and distribution.


title: Dynamics of oscillating relativistic tori around Kerr black holes

abstract:
  We present a comprehensive numerical study of the dynamics of relativistic
axisymmetric accretion tori with a power-law distribution of specific angular
momentum orbiting in the background spacetime of a Kerr black hole. By
combining general relativistic hydrodynamics simulations with a linear
perturbative approach we investigate the main dynamical properties of these
objects over a large parameter space. The astrophysical implications of our
results extend and improve two interesting results that have been recently
reported in the literature. Firstly, the induced quasi-periodic variation of
the mass quadrupole moment makes relativistic tori of nuclear matter densities,
as those formed during the last stages of binary neutron star mergers,
promising sources of gravitational radiation, potentially detectable by
interferometric instruments. Secondly, $p$-mode oscillations in relativistic
tori of low rest-mass densities could be used to explain high frequency
quasi-periodic oscillations observed in X-ray binaries containing a black hole
candidate under conditions more generic than those considered so far.


title:
Spitzer and Hubble Constraints on the Physical Properties of the z~7
  Galaxy Strongly Lensed by Abell 2218

abstract:
  We report the detection of a z~7 galaxy strongly lensed by the massive galaxy
cluster Abell 2218 (z=0.175) at 3.6 and 4.5 um using the Spitzer Observatory
and at 1.1 um using the Hubble Space Telescope. The new data indicate a refined
photometric redshift in the range of 6.6-6.8 depending on the presence of
Ly-alpha emission. The spectral energy distribution is consistent with having a
significant Balmer break, suggesting that the galaxy is in the poststarburst
stage with an age of at least ~50 Myr and quite possibly a few hundred Myr.
This suggests the possibility that a mature stellar population is already in
place at such a high redshift. Compared with typical Lyman break galaxies at
z~3-4, the stellar mass is an order of magnitude smaller (~10^{9} Msun), but
the specific star formation rate (star formation rate/M_{star}) is similarly
large (> 10^{-9} yr^{-1}), indicating equally vigorous star-forming activity.


title: Radial Age and Metal Abundance Gradients in the Stellar Content of M32

abstract:
  We present long-slit spectroscopy of the elliptical galaxy M32, obtained with
the 8-m Subaru telescope at Mauna Kea, the 1.5-m Tillinghast telescope at the
F. L. Whipple Observatory, and the 4-m Mayall telescope at the Kitt Peak
National Observatory. The spectra cover the Lick index red spectral region as
well as higher order Balmer lines in the blue. Spectra have been taken with the
slit off-set from the nucleus to avoid scattered light contamination from the
bright nucleus of M32. An analysis of numerous absorption features,
particularly involving the H$\gamma$ and H$\beta$ Balmer lines, reveals that
systematic radial trends are evident in the integrated spectrum of M32.
Population synthesis models indicate a radial change in both the age and
chemical composition of the light-weighted mean stellar population in M32, from
the nucleus out to 33", i.e., approximately 1.0 effective radius, R_e.
Specifically, the light-weighted mean stellar population at 1 R_e is older, by
\~3 Gyr, and more metal-poor, by ~-0.25 dex in [Fe/H], t han the central value
of ~4 Gyr and [Fe/H]~0.0. We show that this apparent population trend cannot be
attributed to a varying contribution from either hot stars or emission line
contamination. The increase in age and decrease in metal-abundance with radius
are sufficiently well-matched to explain the flat radial color profiles
previously observed in M32. In addition, the ratio of Mg to Fe abundance,
[Mg/Fe], increases from ~-0.25 in the nucleus to ~-0.08 at 1 R_e. Finally, we
find spuriously pronounced line strength gradients in the Mayall data that are
an artifact of scattered light from the bright nucleus. Scattered light issues
may explain the lack of consistency among previously published studies of
radial line strength gradients in M32.


title:
Jet rotation: launching region, angular momentum balance and magnetic
  properties in the bipolar outflow from RW Aur

abstract:
  Using STIS on board the HST we have obtained a spectroscopic map of the
bipolar jet from RW Aur. We find signatures of rotation within the first 300 AU
of the jet (1.''5 from RW Aur). Both lobes rotate in the same direction (i.e.
with different helicities). Toroidal velocities are in the range 5 - 30 km/s at
20 (30) AU from the symmetry axis in the blueshifted (redshifted) lobe, in line
with other STIS observations and with theoretical simulations. The sense of
rotation is anti-clockwise looking from the tip of the blue lobe down to the
star. Rotation is more evident in the [OI] and [NII] lines and at the largest
sampled distance from the axis. We derive that the mass ejected in the observed
part of the outflow is accelerated from a region in the disk within about 0.5
(1.6) AU from the star for the blue (red) lobe. We estimate that the angular
momentum transport rate of the jet can be two thirds or more of the estimated
rate transported through the relevant portion of the disk. The magnetic lever
arm (ratio rA/r0 between the Alfv`en and footpoint radii) is between 3.5 and
4.6 (accuracy 20-25%), or, the ejection index $\xi$ = d ln($\dot{M}_acc$) / d r
is in the range 0.025 - 0.046 (same accuracy).These values are in the range
predicted by the models, and suggest that some heating must be provided at the
base of the flow. We also derive the ratio B_phi / B_p of the toroidal and
poloidal components of the magnetic field at the observed location. B_phi / B_p
= 3.8 +- 1.1 at 30 AU from the axis in the red lobe and -8.9 +- 2.7 at 20 AU
from the axis in the blue lobe. The toroidal component is dominant, as
predicted by magnetic collimation models.


title:
Unresolved H-Alpha Enhancements at High Galactic Latitude in the WHAM
  Sky Survey Maps

abstract:
  We have identified 85 regions of enhanced H-Alpha emission at |b| > 10
degrees subtending approximately 1 degree or less on the Wisconsin H-Alpha
Mapper (WHAM) sky survey. These high latitude ``WHAM point sources'' have
H-Alpha fluxes of 10^{-11} to 10^{-9} erg cm^-2 s^-1, radial velocities within
about 70 km/s of the LSR, and line widths that range from less than 20 km/s to
about 80 km/s (FWHM). Twenty nine of these enhancements are not identified with
either cataloged nebulae or hot stars and appear to have kinematic properties
that differ from those observed for planetary nebulae. Another 14 enhancements
are near hot evolved low mass stars that had no previously reported detections
of associated nebulosity. The remainder of the enhancements are cataloged
planetary nebulae and small, high latitude H II regions surrounding massive O
and early B stars.


title:
Observations of Diffuse EUV Emission with the Cosmic Hot Interstellar
  Plasma Spectrometer (CHIPS)

abstract:
  The Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) was designed to study
diffuse emission from hot gas in the local interstellar cavity in the
wavelength range 90 - 265 A. Between launch in January 2003 and early 2004, the
instrument was operated in narrow-slit mode, achieving a peak spectral
resolution of about 1.4 A FWHM. Observations were carried out preferentially at
high galactic latitudes; weighted by observing time, the mean absolute value of
the galactic latitude for all narrow-slit observations combined is about 45
degrees. The total integration time is about 13.2 Msec (74% day, 26% night). In
the context of a standard collisional ionization equilibrium plasma model, the
CHIPS data set tight constraints on the emission measure at temperatures
between 10^{5.55} K and 10^{6.4} K. At 10^{6.0} K, the 95% upper limit on the
emission measure is about 0.0004 cm^{-6} pc for solar abundance plasma with
foreground neutral hydrogen column of 2 x 10^{18} cm^{-2}. This constraint,
derived primarily from limits on the extreme ultraviolet emission lines of
highly ionized iron, is well below the range for the local hot bubble estimated
previously from soft X-ray studies. To support the emission measures inferred
previously from X-ray data would require depletions much higher than the
moderate values reported previously for hot gas.


title: The South Pole Telescope

abstract:
  A new 10 meter diameter telescope is being constructed for deployment at the
NSF South Pole research station. The telescope is designed for conducting
large-area millimeter and sub-millimeter wave surveys of faint, low contrast
emission, as required to map primary and secondary anisotropies in the cosmic
microwave background. To achieve the required sensitivity and resolution, the
telescope design employs an off-axis primary with a 10m diameter clear
aperture. The full aperture and the associated optics will have a combined
surface accuracy of better than 20 microns rms to allow precision operation in
the submillimeter atmospheric windows. The telescope will be surrounded with a
large reflecting ground screen to reduce sensitivity to thermal emission from
the ground and local interference. The optics of the telescope will support a
square degree field of view at 2mm wavelength and will feed a new 1000-element
micro-lithographed planar bolometric array with superconducting transition-edge
sensors and frequency-multiplexed readouts. The first key project will be to
conduct a survey over approximately 4000 degrees for galaxy clusters using the
Sunyaev-Zel'dovich Effect. This survey should find many thousands of clusters
with a mass selection criteria that is remarkably uniform with redshift. Armed
with redshifts obtained from optical and infrared follow-up observations, it is
expected that the survey will enable significant constraints to be placed on
the equation of state of the dark energy.


title: A Search for Molecular Gas in GHz Peaked Spectrum Radio Sources

abstract:
  We present searches for molecular gas (CO, OH, CS, and Ammonia) in six GHz
Peaked Spectrum (GPS) radio sources. We do not detect gas in any source and
place upper limits on the mass of molecular gas which are generally in the
range 1E9 to a few times 1E10 solar masses. These limits are consistent with
the following interpretations: (1) GPS sources do not require very dense gas in
their hosts, and (2) The GPS sources are unlikely to be confined by dense gas
and will evolve to become larger radio sources.


title:
The Spectrum of Fluctuations in Singularity-free Inflationary Quantum
  Cosmology

abstract:
  We calculate the power spectrum of vacuum fluctuations of a generic scalar
field in a quantum cosmological setting that is manifestly singularity-free.
The power spectrum is given in terms of the usual scale invariant spectrum plus
scale dependent corrections. These are induced by well-defined quantum
fluctuations of de Sitter spacetime, resulting in a modified dispersion
relation for the scalar field. The leading correction turns out to be
proportional to the ratio of Hubble scale and Planck Mass. The maximal relative
change in the spectrum is on the ten percent level and might be observable with
future CMB experiments.


title:
The Nature of Blue Cores in Spheroids: a Possible Connection with AGN
  and Star Formation

abstract:
  We investigate the physical nature of blue cores in early-type galaxies
through the first multi-wavelength analysis of a serendipitously discovered
field blue-nucleated spheroid in the background of the deep ACS/WFC griz
multicolor observations of the cluster Abell 1689. The resolved g-r, r-i and
i-z color maps reveal a prominent blue core identifying this galaxy as a
``typical'' case study, exhibiting variations of 0.5-1.0 mag in color between
the center and the outer regions, opposite to the expectations of reddened
metallicity induced gradients in passively evolved ellipticals. From a
Magellan-Clay spectrum we secure the galaxy redshift at $z=0.624$. We find a
strong X-ray source coincident with the spheroid galaxy. Spectral features and
a high X-ray luminosity indicate the presence of an AGN in the galaxy. However,
a comparison of the X-ray luminosity to a sample derived from the Chandra Deep
Field South displays Lx to be comparable to Type I/QSO galaxies while the
optical flux is consistent with a normal star-forming galaxy. We conclude that
the galaxy's non-thermal component dominates at high-energy wavelengths while
we associate the spheroid blue light with the stellar spectrum of normal
star-forming galaxies. We argue about a probable association between the
presence of blue cores in spheroids and AGN activity.


title: Exploring Novel Signatures for Direct Neutralino Searches

abstract:
  Since the expected rates for neutralino-nucleus scattering are expected to be
small, one should exploit all the characteristic signatures of this reaction.
Such are: (i) In the standard recoil measurements the modulation of the event
rate due to the Earth's motion. (ii) In directional recoil experiments the
correlation of the event rate with the sun's motion. One now has both
modulation, which is much larger and depends not only on time, but on the
direction of observation as well, and a large forward-backward asymmetry. (iii)
In non recoil experiments gamma rays following the decay of excited states
populated during the Nucleus-LSP collision. Branching ratios of about 6 percent
are possible %and (ii) Direct detection of ionization electrons %with branching
ratio with respect to the standard recoil of about 10 per cent.
  (iv) novel experiments in which one observes the electrons produced during
the collision of the LSP with the nucleus. Branching ratios of about 10 per
cent are possible.


title:
Star Clusters in the Galactic Anticenter Stellar Structure: New Radial
  Velocities & Metallicities

abstract:
  The Galactic Anticenter Stellar Structure (GASS) has been identified with
excess surface densities of field stars in several large area sky surveys, and
with an unusual, string-like grouping of star clusters. Some members of the
cluster grouping have radial velocities (RVs) consistent with the observed GASS
velocity-longitude trend. We provide new RV measurements of stars in six
clusters that have been suggested to be associated with the GASS. We show that
the RVs of at least four clusters are consistent with the previously measured
RV trend for GASS. We also derive spectroscopic metallicities for four
clusters, and provide an improved age-metallicity relation for the clusters
apparently associated with GASS.


title:
The DEEP Groth Strip Galaxy Redshift Survey. III. Redshift Catalog and
  Properties of Galaxies

abstract:
  The Deep Extragalactic Evolutionary Probe (DEEP) is a series of spectroscopic
surveys of faint galaxies, targeted at the properties and clustering of
galaxies at redshifts z ~ 1. We present the redshift catalog of the DEEP 1 GSS
pilot phase of this project, a Keck/LRIS survey in the HST/WFPC2 Groth Survey
Strip. The redshift catalog and data, including reduced spectra, are publicly
available through a Web-accessible database. The catalog contains 658 secure
galaxy redshifts with a median z=0.65, and shows large-scale structure walls to
z = 1. We find a bimodal distribution in the galaxy color-magnitude diagram
which persists to z = 1. A similar color division has been seen locally by the
SDSS and to z ~ 1 by COMBO-17. For red galaxies, we find a reddening of only
0.11 mag from z ~ 0.8 to now, about half the color evolution measured by
COMBO-17. We measure structural properties of the galaxies from the HST
imaging, and find that the color division corresponds generally to a structural
division. Most red galaxies, ~ 75%, are centrally concentrated, with a red
bulge or spheroid, while blue galaxies usually have exponential profiles.
However, there are two subclasses of red galaxies that are not bulge-dominated:
edge-on disks and a second category which we term diffuse red galaxies
(DIFRGs). The distant edge-on disks are similar in appearance and frequency to
those at low redshift, but analogs of DIFRGs are rare among local red galaxies.
DIFRGs have significant emission lines, indicating that they are reddened
mainly by dust rather than age. The DIFRGs in our sample are all at z>0.64,
suggesting that DIFRGs are more prevalent at high redshifts; they may be
related to the dusty or irregular extremely red objects (EROs) beyond z>1.2
that have been found in deep K-selected surveys. (abridged)


title: A Solution to the Protostellar Accretion Problem

abstract:
  Accretion rates of order 10^-8 M_\odot/yr are observed in young protostars of
approximately a solar mass with evidence of circumstellar disks. The accretion
rate is significantly lower for protostars of smaller mass, approximately
proportional to the second power of the stellar mass, \dot{M}_accr\propto M^2.
The traditional view is that the observed accretion is the consequence of the
angular momentum transport in isolated protostellar disks, controlled by disk
turbulence or self--gravity. However, these processes are not well understood
and the observed protostellar accretion, a fundamental aspect of star
formation, remains an unsolved problem. In this letter we propose the
protostellar accretion rate is controlled by accretion from the large scale gas
distribution in the parent cloud, not by the isolated disk evolution.
Describing this process as Bondi--Hoyle accretion, we obtain accretion rates
comparable to the observed ones. We also reproduce the observed dependence of
the accretion rate on the protostellar mass. These results are based on
realistic values of the ambient gas density and velocity, as inferred from
numerical simulations of star formation in self--gravitating turbulent clouds.


title: Angular Correlation Estimates for Ultrahigh Energy Cosmic Rays

abstract:
  Anisotropy in arrival directions of ultrahigh energy cosmic rays offers the
most direct way to search for the sources of these particles. We present
estimates of the angular correlation in the HiRes sample of stereo events above
10 EeV, and in the combined sample of HiRes and AGASA events above 40 EeV.


title:
Submillimeter Array Observations of Disks in the SR 24 Multiple Star
  System

abstract:
  We present high-resolution aperture synthesis images from the Submillimeter
Array of the 225 GHz (1.3 mm) continuum and CO J=2-1 line emission from the
disks around components of the hierarchical triple system SR 24, located in the
Ophiuchus star-forming region. The most widely separated component, SR 24 S
(with a projected semimajor axis of 832 AU), has a circumstellar disk with
properties typical of those around single T Tauri stars. The binary SR 24 N
(with a projected semimajor axis of 32 AU) is undetected in the continuum, but
has strong, resolved CO emission which likely originates in a circumbinary disk
with a central gap. The data constrain the total disk mass in the SR 24 N
system to be < 10^-3 M_sun and indicate that the depletion of CO onto dust
grains is not more than 100 times larger than the mean value in the
interstellar medium. The SR 24 N disk is unusual in that it is only detected in
line emission. It is possible that other low mass disks around binaries and
single stars may have been missed in single-dish continuum surveys.


title:
The Environmental Dependence of Galaxy Properties in the Local Universe:
  Dependence on Luminosity, Local Density, and System Richness

abstract:
  We investigate the environmental dependence of star formation and the
morphology of galaxies in the local universe based on a volume-limited sample
(0.030<z<0.065 and M_r<M_r^*+2) constructed from the data of the Sloan Digital
Sky Survey. First, we focus on how galaxy properties change with local density.
The star formation and morphology show a 'break' at the critical local density
of log Sigma_crit~0.4 galaxies h_75^2 Mpc^-2, which is in agreement with
previous studies. However, the break can be seen only for faint galaxies
(M^*_r+1 < M_r < M^*_r+2), and bright galaxies (M_r < M^*_r+1) show no break.
Thus, galaxies of different luminosities are found to show different
environmental dependencies. Next, we examine dependencies on richness of galaxy
systems. Star formation activities of galaxies are different from those of
field galaxies even in systems as poor as sigma~100 km/s. This result suggests
that environmental mechanisms that are effective only in rich systems, such as
ram-pressure stripping of cold gas and harassment, have not played a major role
in transforming galaxies into red early-type galaxies. Strangulation and
interactions between galaxies, however, remain candidates of the driver of the
environmental dependence. In the dense environments in the local universe, the
slow transformation of faint galaxies occurs to some extent, but the
transformation of bright galaxies is not clearly visible. We suggest that the
evolution of bright galaxies is not strongly related to galaxy system, such as
groups and clusters, while the evolution of faint galaxies is likely to be
closely connected to galaxy system.


title: The K-band intensity profile of R Leonis probed by VLTI/VINCI

abstract:
  We present near-infrared K-band interferometric measurements of the Mira star
R Leonis obtained in April 2001 and January 2002 with the VLTI, the
commissioning instrument VINCI, and the two test siderostats. These epochs
correspond to near-maximum stellar variability phases $\sim$ 0.08 and $\sim$
1.02 (one cycle later), respectively. The April 2001 data cover a range of
spatial frequencies (31--35 cycles/arcsecond) within the first lobe of the
visibility function. These measurements indicate a center-to-limb intensity
variation (CLV) that is clearly different from a uniform disk (UD) intensity
profile. We show that these measured visibility values are consistent with
predictions from recent self-excited dynamic Mira model atmospheres that
include molecular shells close to continuum-forming layers. We derive
high-precision Rosseland diameters of 28.5 +/- 0.4 mas and 26.2 +/- 0.8 mas for
the April 2001 and January 2002 data, respectively. Together with literature
estimates of the distance and the bolometric flux, these values correspond to
linear radii of 350^{+50}_{-40}R$_\odot$ and 320^{+50}_{-40}R$_\odot$, and to
effective temperatures of 2930 +/- 270K and 3080 +/- 310K, respectively.


title:
Extragalactic Background Light: new constraints from the study of the
  photon-photon absorption on blazar spectra

abstract:
  The study of the Extragalactic Background Light (EBL) is crucial to
understand many astrophysical problems (as the formation of first stars, the
evolution of galaxies and the role of dust emission). At present, one of the
most powerful ways to put constraints on EBL is represented by the study of the
photon-photon absorption on gamma-ray spectra of TeV blazars. Adopting this
method, we found that, if the only contribution to the optical and Near
Infrared (NIR) background is given by galaxies, the spectrum of the blazar
H1426+428 cannot be fitted. To reproduce the observational data of H1426+428 a
Near Infrared excess with respect to galaxy counts is required, with amplitude
consistent with both the Matsumoto et al. (2000) data with Kelsall's model of
zodiacal light (ZL) subtraction and the DIRBE data with Wright's model of ZL
subtraction. The derived constraints on the optical EBL are weaker, because the
experimental errors on blazar data are still bigger than the differences among
various optical EBL models. In the mid-infrared the SPITZER measurement at 24
micron provides the best fit of the blazar spectrum.


title:
Single Star-forming galaxies and Star-forming galaxies in SF+SF and
  mixed pairs

abstract:
  We compare the SFR of single star-forming galaxies with the SFR of
star-forming galaxies in pairs. Volume-limited samples are compared selected
from the 2dFGRS, applying a maximum magnitude difference criterion. We show
that SF galaxies in SF + SF pairs typically increase their SFR as they get
fainter, whereas this does not happen for SF galaxies in mixed (SF + passive)
pairs. And we provide evidence that differences between single SF and SF in
pairs get more significant when SF galaxies in mixed pairs are excluded from
the pair sample. Our analysis confirms that enhanced SFR and the presence of a
companion galaxy (on 0.5 h^-1 Mpc scale) are correlated quantities, provided
the galaxy is neither too luminous nor too faint, and the triggering galaxy is
itself a SF galaxy.


title:
VINCI-VLTI measurements of HR 4049: the physical size of the
  circumbinary envelope

abstract:
  We present the first detection of the envelope which surrounds the post-AGB
binary source HR 4049. VINCI-VLTI K-band interferometric observations of this
source imply the existence of a large structure with a Gaussian angular FWHM
22.4 +/- 1.4 mas or uniform disk diameter of 34.9 +/- 1.9 mas. With the
Hipparcos parallax of 1.50 +/- 0.64 mas these values correspond to a physical
size of 14.9 (+11.1,-4.4) AU and 23.3 (+17.3,-7.0) AU, respectively. Our
measurements, covering an azimuth range of about 60 degrees, for the
sky-projected baseline, provide information on the geometry of the emitting
region and show that there is only a slight variation of the measured angular
values along the different directions sampled. Thus, our results are consistent
with a spherical geometry of the envelope. However, we cannot completely rule
out the existence of an asymmetric envelope (like the circumbinary disk
envisaged by some recent models) because of the limited spatial frequency and
azimuth range covered by the observations.


title:
Variable stars in the dwarf irregular galaxy NGC 6822: the photometric
  catalogue

abstract:
  Deep B,V time-series photometry obtained with the ESO Very Large Telescope
has been used to identify variable stars in the dwarf irregular galaxy NGC
6822. We surveyed a 6.8x6.8 arcmin area of the galaxy and detected a total
number of 390 candidate variables with the optimal image subtraction technique
(Alard 2000). Light curves on a magnitude scale were obtained for 262 of these
variables. Differential flux light curves are available for the remaining
sample. In this paper we present the photometric catalogue of calibrated light
curves and time-series data, along with coordinates and classification of the
candidate variables. A detailed description is provided of the procedures used
to identify the variable stars and calibrate their differential flux light
curves on a magnitude scale.


title: Q0957+561 revised: CO emission from a disk at z=1.4

abstract:
  Based on additional interferometric observations, we reanalysed the CO(2-1)
and 3mm continuum emission of Q0957+561, a lensed QSO at a redshift of
z=1.4141. The emission in the CO(2-1) lines reveals a gas-rich host galaxy with
a peculiar double-peaked profile at one of the two lensed images. Our new
interferometric CO maps of the host galaxy agree well with HST images obtained
by Keeton et al. (2000) and we thus argue that the two velocity components
arise from molecular gas in the disk of the host galaxy. We also present new
model calculations, all in excellent agreement with recent time delay
measurements and simulations.


title:
Primary Energy Spectrum and Mass Composition Determined with the Tunka
  EAS Cherenkov Array

abstract:
  New results of 300 hours of operation of the Tunka array are presented.
  An improved parametrization of the Cherenkov light lateral distribution
function (LDF), based on CORSIKA Monte Carlo simulations and the experiment
QUEST, has been used for the reconstruction of EAS parameters. The corrected
energy spectrum in the knee region is obtained. The mean depth of the EAS
maximum has been derived both from the analysis of LDF steepness and the FWHM
of Cerenkov light pulse. The mean mass composition around the knee is
estimated.


title: The general relativistic MHD dynamo equation

abstract:
  The magnetohydrodynamic dynamo equation is derived within general relativity,
using the covariant 1+3 approach, for a plasma with finite electric
conductivity. This formalism allows for a clear division and interpretation of
plasma and gravitational effects, and we have not restricted to a particular
spacetime geometry. The results should be of interest in astrophysics and
cosmology, and the formulation is well suited to gauge invariant perturbation
theory. Moreover, the dynamo equation is presented in some specific limits. In
particular, we consider the interaction of gravitational waves with magnetic
fields, and present results for the evolution of the linearly growing
electromagnetic induction field, as well as the diffusive damping of these
fields.


title:
X-ray Line Emitting Objects in XMM-Newton Observations: the Tip of the
  Iceberg

abstract:
  We present preliminary results from a novel search for X-ray Line Emitting
Objects (XLEOs) in XMM-Newton images. Three sources have been detected in a
test-run analysis of 13 XMM-Newton observations. The three objects found are
most likely extremely absorbed AGN characterized by a column density
NH~10^24cm^-2. Their redshift has been directly determined from the X-ray data,
by interpreting the detected emission line as the 6.4 keV Fe line. The measured
equivalent width of the X-ray line is, in all three cases, several keV. This
pilot study demonstrates the success of our search method and implies that a
large sample of XLEOs can be obtained from the public XMM-Newton data archive.


title:
Subarcsecond mid-infrared and radio observations of the W3 IRS5
  protocluster

abstract:
  Observations at mid-infrared (4.8-17.65 um) and radio (0.7-1.3 cm)
wavelengths are used to constrain the structure of the high-mass star-forming
region W3 IRS5 on 0.1'' (200 AU) scales. Two bright mid-infrared sources are
detected, as well as diffuse emission. The bright sources have associated
compact radio emission and probably are young high-mass stars.
  The measured sizes and estimated temperatures indicate that these sources
together can supply the observed far-infrared luminosity. However, an optically
thick radio source with a possible mid-infrared counterpart may also contribute
significant luminosity; if so, it must be extremely deeply embedded.
  The infrared colour temperatures of 350-390 K and low radio brightness
suggest gravitational confinement of the H II regions and ongoing accretion at
a rate of a few 10^-8 M0/yr or more. Variations in the accretion rate would
explain the observed radio variability. The low estimated foreground extinction
suggests the existence of a cavity around the central stars, perhaps blown by
stellar winds.
  At least three radio sources without mid-infrared counterparts appear to show
proper motions of ~100 km/s, and may be deeply embedded young runaway OB stars,
but more likely are clumps in the ambient material which are shock-ionized by
the OB star winds.


title: The QCD Black Disk Limit in Cosmic Ray Air Showers

abstract:
  We discuss particle production in the high energy limit of QCD. Due to a
large gluon density, the interaction reaches the black disk limit and the
projectile is resolved into its partonic structure at the saturation scale.
This leads to suppression of forward particle production and hereby to a faster
absorption of cosmic ray air showers. This property is most suitable for the
distinction of evolution scenarios for the saturation scale, e.g. fixed and
running coupling BFKL, the latter of which is favored by air shower
measurements.


title: Hybrid Simulation of Cosmic Ray Air Showers

abstract:
  Air shower simulations are essential for interpreting data from cosmic ray
experiments. At highest energies though, a microscopic treatment of a whole
shower is not possible any more, since it would require a huge amount of
CPU-time. We review hybrid approaches of air shower simulation which try to
overcome this problem without giving rise to artificial fluctuations as
generated by the thinning algorithm.


title:
Hysteresis in spectral state transitions - a challenge for theoretical
  modeling

abstract:
  Many low-mass X-ray binaries show both hard and soft spectral states. For
several sources the transitions between these states have been observed, mostly
from the soft to the hard state during a luminosity decrease. In a few cases
also the transition from the hard to the soft state was observed, coincident
with an increase of the luminosity. Surprisingly this luminosity was not the
same as the one during a following change back to the hard state. The values
differed by a factor of about 3 to 5. We present a model for this hysteresis in
the light curves of low-mass X-ray binaries (sources with neutron stars or
black holes). We show that the different amount of Compton cooling or heating
acting on the accretion disk corona at the time of the transition causes this
switch in the accretion mode at different mass accretion rates and therefore
different luminosities. The inner disk during the soft state provides a certain
amount of Compton cooling which is either not present or much less if the inner
region is filled with a hot advection-dominated accretion flow (ADAF) that
radiates a hard spectrum.


title: BL Lac contribution to the Extragalactic Gamma-Ray Background

abstract:
  Very high energy gamma-rays(E>20GeV) from blazars traversing cosmological
distances through the metagalactic radiation field can convert to
electron-positron pairs in photon-photon collisions. The converted gamma-rays
initiate electromagnetic cascades driven by inverse-Compton scattering off the
microwave background photons. The cascades shift the injected gamma ray
spectrum to MeV-GeV energies. Randomly oriented magnetic fields rapidly
isotropize the secondary electron-positron beams resulting from the beamed
blazar gamma ray emission, leading o faint gamma-ray halo. Using a model for
the time-dependent metagalactic radiation field consistent with all currently
available far-infrared-to-optical data, we compute (i) the expected gamma-ray
attenuation in blazar spectra, and (ii) the cascade contribution from faint,
unresolved blazars to the extragalactic gamma-ray background as measured by
EGRET, assuming a generic emitted spectrum extending to an energy of 10 TeV.
The latter cascade contribution to the EGRET background is fed by the assumed
>20 GeV emission from the hitherto undiscovered sources, and we estimate their
dN-dz distribution taking into account that the nearby (z<0.2) fraction of
these sources must be consistent with the known (low) numbers of sources above
300 GeV.


title:
The Absorption Spectrum of High-Density Stellar Ejecta in the
  Line-of-Sight to Eta Carinae

abstract:
  Using the high dispersion NUV mode of the Space Telescope Imaging
Spectrograph (STIS) aboard the Hubble Space Telescope (HST) to observe Eta
Carinae, we have resolved and identified over 500 sharp, circumstellar
absorption lines of iron-group singly-ionized and neutral elements with ~20
velocity components ranging from -146 km/s to -585 km/s. These lines are from
transitions originating from ground and metastable levels as high as 40,000
cm-1 above ground. The absorbing material is located either in dense
inhomogeneities in the stellar wind, the warm circumstellar gas immediately in
the vicinity of Eta Carinae, or within the cooler foreground lobe of the
Homunculus. We have used classical curve-of-growth analysis to derive atomic
level populations for FeII at -146 km/s and for TiII at -513 km/s. These
populations, plus photoionization and statistical equilibrium modeling, provide
electron temperatures, Te, densities, n, and constraints on distances from the
stellar source, r. For the -146 km/s component, we derive Te = 6400 K,
n(H)>10e7 - 10e8 cm-3, and d ~1300 AU. For the -513 km/s component, we find a
much cooler temperature, Te= 760 K, with n(H)> 10e7cm-3, we estimate d~10,000
AU. The large distances for these two components place the absorptions in the
vicinity of identifiable ejecta from historical events, not near or in the
dense wind of Eta Carinae. Further analysis, in parallel with obtaining
improved experimental and theoretical atomic data, is underway to determine
what physical mechanisms and elemental abundances can explain the large number
of strong circumstellar absorption features in the spectrum of Eta Carinae.


title:
Dust and Ionized Gas in Nine Nearby Early-Type Galaxies Imaged with the
  HST Advanced Camera for Surveys

abstract:
  We present $V$ and $I$ continuum images and H$\alpha$+[N II] maps of nine
early-type galaxies observed with the Wide Field Channel of the Advanced Camera
for Surveys on the Hubble Space Telescope. Dust and ionized gas are detected in
all galaxies. The optical nebulae are primarily concentrated on the nuclei and
extend out to radii of a few hundred parsecs, in compact clumps, filaments, or
disks. Two galaxies, NGC 6166 and NGC 6338, also possess diffuse, ionized
filaments on kiloparsec scales. The ionized gas is entirely contained within
the nuclear disks of ESO 208-G021, NGC 3078, and NGC 7720. In the radio-loud
galaxy NGC 6166, emission-line filaments are detected along the radio lobes,
possibly as a result of shock ionization. A wide range of ionized gas masses,
$M_g\approx7\times10^2-3\times10^6$ $M_\odot$, are calculated from the observed
fluxes. Even in this small sample, the orientation of the ionized material
correlates well with the major or minor axis of the galaxies, consistent with
an external origin for the dust and gas.


title:
Attacking the X-ray emission properties of young stars with the Sword of
  Orion

abstract:
  We present a survey of X-ray emission from young stars in the Sword of Orion
star-formation region using XMM-Newton's EPIC detectors. We find over 850 X-ray
sources, of which more than 700 have near-infrared counterparts consistent with
being young stars. The survey enables statistical investigation of the
dependence of X-ray emission properties of young stars on fundamental stellar
parameters (mass, rotation, age) and environmental features (circumstellar
disk, active accretion, circumstellar absorption), and study of structure size
in individual coronae through analysis of large flares.


title:
Primordial Nucleosynthesis with varying fundamental constants: A
  semi-analytical approach

abstract:
  Using the semi-analytic method proposed by \citet{Esma91} we calculate the
abundances of the light elements produced during primordial nucleosynthesis
assuming that the gauge coupling constants of the fundamental interactions may
vary. We analyze the dependence of the nucleon masses, nuclear binding energies
and cross sections involved in the calculation of the abundances with the
fundamental constants assuming the chiral limit of QCD. The abundances of light
elements as a function of the fundamental constants are obtained. Finally,
using the observational data of $\De$, $\Het$, $\He$ and $\Li$ we estimate
constraints on the variation of the fundamental constants between the
primordial nucleosynthesis and the present. All observational abundances and
the WMAP estimate of the baryon density, can be fitted to the theoretical
predictions with varying coupling constants. The possible systematic errors in
the observational data, precludes from stronger conclusions.


title: Missing Baryons in the Warm-Hot Intergalactic Medium

abstract:
  We briefly review the use of UV absorption lines in the spectra of
low-redshift QSOs for the study of the physical conditions, metallicity, and
baryonic content of the low-z IGM, with emphasis on the missing baryons
problem. Current results on the statistics and baryonic content of intervening,
low-z O VI and Lya absorption-line systems are presented with some comments on
overlap between these two classes of absorbers and consequent baryon
double-counting problems. From observations of a sample of 16 QSOs observed
with the E140M echelle mode of STIS, we find 44 intervening O VI absorbers and
14 associated O VI systems [i.e, z(abs) ~ z(QSO)]. The implied number of
intervening O VI absorbers per unit redshift is dN/dz(O VI) = 23+/-4 for rest
equivalent width > 30 mA. The intervening O VI systems contain at least 7% of
the baryons if their typical metallicity is 1/10 solar and the O VI ion
fraction is <0.2. This finding is consistent with predictions made by
cosmological simulations of large-scale structure growth. Recently, a
population of remarkably broad Lya lines have been recognized in low-z quasar
spectra. If these Lya lines are predominantly thermally broadened, then these H
I absorbers likely harbor an important fraction of the baryons. We present and
discuss some examples of the broad Lya absorbers. Finally, we briefly summarize
some findings on the relationships between O VI absorbers and nearby
galaxies/large-scale structures.


title:
How Universal is the Gunn-Peterson Trough at z~6?: A Closer Look at the
  Quasar SDSS J1148+5251

abstract:
  Detectable flux is visible in the Ly-alpha and Ly-beta troughs of the highest
redshift ($z=6.42$) quasar found to date, SDSS J1148+5251. This has previously
been interpreted as continuum contamination from an interloper galaxy at
z=4.94. We examine the Ly-gamma trough of SDSS J1148+5251 and show that this
interpretation is untenable: the spectrum does not show the continuum break in
a z=4.94 galaxy expected from absorption by the intervening Ly-alpha forest.
Therefore, flux must be leaking through at least one of the troughs from the
quasar itself. Contrary to previous claims, the flux ratios in the Ly-alpha and
Ly-beta troughs are consistent with pure transmission. From the Ly-gamma
trough, we place an upper bound on the effective Ly-alpha optical depth at
z~6.2 of tau < 14.3 (2 sigma). This implies a highly ionized IGM along this
line of sight and significant cosmic variance in the transition toward complete
Gunn-Peterson absorption. Detailed study of the observed transmission features
will shed light on this era.


title: Beyond the Standard Model of Cosmology

abstract:
  Recent cosmological observations of unprecented accuracy, by WMAP in
particular, have established a `Standard Model' of cosmology, just as LEP
established the Standard Model of particle physics. Both Standard Models raise
open questions whose answers are likely to be linked. The most fundamental
problems in both particle physics and cosmology will be resolved only within a
framework for Quantum Gravity, for which the only game in town is string
theory. We discuss novel ways to model cosmological inflation and late
acceleration in a non-critical string approach, and discuss possible
astrophysical tests.


title:
Gaussianity of the CMB: Smooth Goodness of Fit Tests Applied to
  Interferometric Data

abstract:
  We adapt the smooth tests of goodness of fit developed by Rayner and Best to
the study of the non-Gaussianity of interferometric observations of the cosmic
microwave background (CMB). The interferometric measurements (visibilities) are
transformed into signal-to-noise eigenmodes, and then the method is applied
directly in Fourier space. This transformation allows us to perform the
analysis in different subsets of eigenmodes according to their signal-to-noise
level. The method can also deal with non-uniform or incomplete coverage of the
UV plane. We explore here two possibilities: we analyse either the real and
imaginary parts of the complex visibilities (Gaussianly distributed under the
Gaussianity hypothesis) or their phases (uniformly distributed under the
Gaussianity hypothesis). The power of the method in discriminating between
Gaussian and non-Gaussian distributions is studied by using several kinds of
non-Gaussian simulations. On the one hand, we introduce a certain degree of
non-Gaussianity directly into the Fourier space using the Edgeworth expansion,
and afterwards the desired correlation is introduced. On the other hand, we
consider interferometric observations of a map with topological defects (cosmic
strings). To these previous non-Gaussian simulations we add different noise
levels and quantify the required signal-to-noise ratio necessary to achieve a
detection of these non-Gaussian features. Finally, we have also studied the
ability of the method to constrain the so-called nonlinear coupling constant
f_{NL} using chi^2 simulations.The whole method is illustrated here by
application to simulated data from the Very Small Array interferometer.


title: RCS043938-2904.9: A New Rich Cluster of Galaxies at z=0.951

abstract:
  We present deep I, J_s, K_s imaging and optical spectroscopy of the newly
discovered Red-Sequence Cluster Survey cluster RCS043938-2904.9. This cluster,
drawn from an extensive preliminary list, was selected for detailed study on
the basis of its apparent optical richness. Spectroscopy of 11 members places
the cluster at z=0.951 +- 0.006, and confirms the photometric redshift estimate
from the (R-z) color-magnitude diagram. Analysis of the infrared imaging data
demonstrates that the cluster is extremely rich, with excess counts in the
Ks-band exceeding the expected background counts by 9 sigma. The properties of
the galaxies in RCS043938-2904.9 are consistent with those seen in other
clusters at similar redshifts. Specifically, the red-sequence color, slope and
scatter, and the size-magnitude relation of these galaxies are all consistent
with that seen in the few other high redshift clusters known, and indeed are
consistent with appropriately evolved properties of local cluster galaxies. The
apparent consistency of these systems implies that the rich, high-redshift RCS
clusters are directly comparable to the few other systems known at z ~ 1, most
of which have been selected on the basis of X-ray emission.


title: Spin, Accretion and the Cosmological Growth of Supermassive Black Holes

abstract:
  If supermassive black holes (SMBHs) are the energy sources that power quasars
and active galactic nuclei, then QSO SDSS 1148+5251, the quasar with the
highest redshift (z_QSO=6.43), hosts a supermassive black hole formed within
0.9 Gyr after the Big Bang. This requirement places constraints on the
cosmological formation of SMBHs, believed to grow from smaller initial seeds by
a combination of accretion and mergers. We focus on gas accretion onto seeds
produced by the collapse of Pop III stars at high redshift. We incorporate the
results of recent relativistic, MHD simulations of disk accretion onto Kerr
black holes to track the coupled evolution of the masses and spins of the
holes. We allow for an additional amplification of ~10^4 in the mass of a
typical seed due to mergers, consistent with recent Monte Carlo simulations of
hierarchical mergers of cold, dark matter halos containing black hole seeds. We
find that the growth of Pop III black hole seeds to ~10^9 M_sun by z_QSO = 6.43
favors MHD accretion disks over standard thin disks. MHD disks tend to drive
the holes to a submaximal equilibrium spin rate a/M ~ 0.95 and radiation
efficiency epsilon_M ~ 0.2, while standard thin disks drive them to maximal
spin (a/M = 1) and efficiency (epsilon_M = 0.42). This small difference in
efficiency results in a huge difference in mass amplification by accretion at
the Eddington limit. The MHD equilibrium efficiency is consistent with the
observed ratio of the QSO plus AGN luminosity density to the local SMBH mass
density. Our prototype analysis is designed to stimulate the incorporation of
results from relativistic stellar collapse and MHD accretion simulations in
future Monte Carlo simulations of hierarchical structure formation to better
determine the cosmological role of SMBHs and their mass and spin distributions.


title: A Pre-Protostellar Core in L1551

abstract:
  Large field surveys of NH3, C2S, 13CO and C18O in the L1551 dark cloud have
revealed a prolate, pre-protostellar molecular core (L1551-MC) in a relatively
quiescent region to the northwest of the well-known IRS 5 source. The kinetic
temperature is measured to be 9K, the total mass is ~2Msun, and the average
particle density is 10^4-10^5 cm^(-3). L1551-MC is 2.25' x 1.11' in projection
oriented at a position angle of 133deg. The turbulent motions are on the order
of the sound speed in the medium and contain 4% of the gravitational energy,
E_{grav}, of the core. The angular momentum vector is projected along the major
axis of L1551-MC corresponding to a rotational energy of 2.5E-3(sin
i)^(-2)|E_{grav}|. The thermal energy constitutes about a third of |E_{grav}|
and the virial mass is approximately equal to the total mass. L1551-MC is
gravitationally bound and in the absence of strong, ~160 microgauss, magnetic
fields will likely contract on a ~0.3 Myr time scale. The line profiles of many
molecular species suggest that the cold quiescent interior is surrounded by a
dynamic, perhaps infalling envelope which is embedded within the ambient
molecular gas of L1551.


title: A New Cataclysmic Variable in Hercules

abstract:
  We present time-series observations, spectra and archival outburst data of a
newly-discovered variable star in Hercules, Var Her 04. Its orbital period,
mass ratio, and outburst amplitude resemble those of the UGWZ-type subclass of
UGSU dwarf novae. However, its supercycle and outburst light curve defy
classification as a clear UGWZ. Var Her 04 is most similar to the small group
of possible hydrogen-burning ``period bouncers'', dwarf novae that have passed
beyond the period minimum and returned.