title:
The Pursuit of Non-Gaussian Fluctuations in the Cosmic Microwave
  Background

abstract:
  We present theoretical and observational studies of non-Gaussian fluctuations
in CMB, by using the angular bispectrum and trispectrum. We predict the primary
angular bispectrum from inflation, and forecast how well we can measure the
primordial non-Gaussian signal. In addition to that, secondary anisotropy
sources in the low-redshift universe also produce non-Gaussianity, so do
foreground emissions from extragalactic or interstellar microwave sources. We
study how well we can measure these non-Gaussian signals, including the
primordial signal. We find that slow-roll inflation produces too small
bispectrum to be detected by any experiments; thus, any detection strongly
constrains this class of models. We also find that the secondary bispectrum
from coupling between the SZ effect and the weak lensing effect, and the
foreground bispectrum from extragalactic point sources, give detectable
non-Gaussian signals on small angular scales. We test Gaussianity of the COBE
DMR sky maps, by measuring all the modes of the angular bispectrum down to the
DMR beam size. We find no significant signal of the bispectrum. We also find
that the previously reported detection of the bispectrum is consistent with a
statistical fluctuation. By fitting the theoretical prediction to the data for
the primary bispectrum, we put a constraint on non-linearity in inflation. We
conclude that the angular bispectrum finds no significant non-Gaussian signals
in the DMR data. We present the first measurement of the angular trispectrum on
the DMR sky maps, further testing Gaussianity of the DMR data. We find no
significant non-Gaussian signals in the trispectrum. Therefore, the angular
bispectrum and trispectrum show that the DMR sky map is comfortably consistent
with Gaussianity.


title:
The Detectability of Neutralino Clumps via Atmospheric Cherenkov
  Telescopes

abstract:
  High resolution N-body simulations have revealed the survival of considerable
substructure within galactic halos. Assuming that the predicted dark matter
clumps are composed of annihilating neutralinos, we examine their detectability
via Atmospheric Cherenkov Telescopes (ACTs). Depending on their density
profile, individual neutralino clumps should be observable via their gamma-ray
continuum and line emissions. We find that the continuum signal is the most
promising signal for detecting a neutralino clump, being significantly stronger
than the monochromatic signals. Limits from the line detectability can help
lift degeneracies in the supersymmetric (SUSY) parameter space. We show that by
combining the observations of different mass clumps, ACTs can explore most of
the SUSY parameter space. ACTs can play a complementary role to accelerator and
gamma-ray satellite limits by exploring relatively large neutralino masses and
less concentrated clumps. We develop a strategy for dark matter clump studies
by future ACTs based on VERITAS specifications and encourage the development of
techniques to identify primaries. This can reduce the background by an order of
magnitude.


title: Dense Molecular Gas in Lenticular Galaxies

abstract:
  We made CO and HCN simultaneous observations of lenticular galaxies, NGC 404,
NGC 3593 and NGC 4293, and detected HCN emission in NGC 3593 and NGC 4293 as
well as CO in all the galaxies. The I(HCN)/I(CO) ratios were 0.025+-0.006 and
0.066+-0.005 in NGC 3593 and NGC 4293, respectively, which are comparable to
the late-type spiral galaxies. The average of the I(HCN)/I(CO) ratios at the
center of 12 nearby spiral galaxies including late-type was 0.055+-0.028. The
line profiles of CO and HCN emission showed different shape in both galaxies.
The HCN peaks were not at the systemic velocity of these galaxies, while the CO
peaks were near the systemic velocity. These results suggest that the fraction
of the dense molecular gas is high around the center in these galaxies.


title: Structural Parameters for Globular Clusters in NGC 5128

abstract:
  We present new imaging measurements of 27 individual globular clusters in the
halo of the nearby elliptical galaxy NGC 5128, obtained with the Hubble Space
Telescope STIS and WFPC2 cameras. Combining these with similar data for
selected inner-halo clusters from Holland et al. 1999 (AAp, 348, 418), we now
have a total sample of 43 NGC 5128 globular clusters with measured structural
properties. Classic King-model profiles match the clusters extremely well, and
their core- and half-light radii, central surface brightness, and central
concentration fall in very much the same range as do the clusters in the Milky
Way and M31. We find half a dozen bright clusters which show tentative evidence
for light that extends beyond the nominal tidal radius, or possibly ones in
which anisotropic velocity distributions are important. We also confirm
previous indications that NGC 5128 contains relatively more clusters with large
(> 0.2) ellipticity than does the Milky Way. Finally, calculations of the
cluster binding energies E_b as defined by McLaughlin 2000 (ApJ, 539,618) show
that the NGC 5128 clusters occupy the same extremely narrow region of the
parametric ``fundamental plane'' as do their Milky Way counterparts. Our data
are thus strongly consistent with the claim that the globular clusters in both
NGC 5128 and the Milky Way are fundamentally the same type of object: old star
clusters with similar mass-to-light ratios and King-model structures.


title:
Comparative study of simulations of Cerenkov radio emission from high
  energy showers in dense media

abstract:
  We compare in detail the results of simulations of electromagnetic showers in
ice in the GeV-TeV energy range, using both the GEANT package and the ZHS Monte
Carlo, a code specifically designed to calculate coherent Cerenkov radio pulses
from electromagnetic showers in dense media. The longitudinal and lateral
profiles as well as the tracklengths, and excess tracklengths are shown to
agree at the 10% level. We briefly comment on the negligible influence of the
Landau-Pomeranchuk-Migdal effect on the total shower tracklength. Our results
are relevant for experiments exploiting the radio Cerenkov technique in dense
media as well as for other detectors that rely on the Cerenkov effect in water
or ice.


title: Protostellar Collapse Induced by Compression

abstract:
  We present numerical simulations of the evolution of low-mass, isothermal,
molecular cores which are subjected to an increase in external pressure $P\xt$.
If $P\xt$ increases very slowly, the core approaches instability quite
quasistatically. However, for larger (but still quite modest) $dP\xt/dt$ a
compression wave is driven into the core, thereby triggering collapse from the
outside in. If collapse of a core is induced by increasing $P\xt$, this has a
number of interesting consequences. (i) The density profile is approximately
flat in the centre during the prestellar phase (i.e. before the compression
wave converges on the centre creating the central protostar). (ii) During the
prestellar phase there are (subsonic) inward velocities in the outer layers of
the core, whilst the inner parts are still approximately at rest. (iii) There
is an initial short phase of rapid accretion (notionally the Class 0 phase),
followed by a longer phase of slower accretion (the Class I phase). All these
features accord well with observation, but are at variance with the predictions
of the standard theory of star formation based on the inside-out collapse of a
singular isothermal sphere. We note that the setting up of a coherent inward
velocity field appears to be a generic feature of compression waves; and we
speculate that interactions and interference between such velocity fields may
play a crucial r\^ole in initiating the fragmentation of cores and the genesis
of multiple star systems.


title:
Gamma-ray line emission from OB associations and young open clusters.
  II. The Cygnus region

abstract:
  Gamma-ray and microwave observations of the Cygnus region reveal an intense
signal of 1.809 MeV line emission, attributed to radioactive decay of 26Al,
that is closely correlated with 53 GHz free-free emission, originating from the
ionised interstellar medium. We modelled both emissions using a
multi-wavelength evolutionary synthesis code for massive star associations that
we applied to the known massive star populations in Cygnus. For all OB
associations and young open clusters in the field, we determined the population
age, distance, and richness as well as the uncertainties in all these
quantities from published photometric and spectroscopic data. We propagate the
population uncertainties in model uncertainties by means of a Bayesian method.
The young globular cluster Cyg OB2 turns out to be the dominant 26Al
nucleosynthesis and ionisation source in Cygnus. Our model reproduces the
ionising luminosity of the Cygnus region very well, yet it underestimates 26Al
production by about a factor of 2. We attribute this underestimation to
shortcomings of current nucleosynthesis models, and suggest the inclusion of
stellar rotation as possible mechanism to enhance 26Al production. We also
modelled 60Fe nucleosynthesis in the Cygnus region, yet the small number of
recent supernova events suggests only little 60Fe production. Consequently, a
detection of the 1.137 MeV and 1.332 MeV decay lines of 60Fe from Cygnus by the
upcoming INTEGRAL observatory is not expected.


title: Period Changes of the SMC Cepheids from the Harvard, OGLE and ASAS Data

abstract:
  Comparison of the old observations of Cepheids in the Small Magellanic Cloud
from the Harvard data archive, with the recent OGLE and ASAS observations
allows an estimate of their period changes. All of matched 557 Cepheids are
still pulsating in the same mode. One of the Harvard Cepheid, HV 11289, has
been tentatively matched to a star which is now apparently constant. Cepheids
with log P > 0.8 show significant period changes, positive as well as negative.
We found that for many stars these changes are significantly smaller than
predicted by recent model calculations. Unfortunately, there are no models
available for Cepheids with periods longer than approximatelly 80 days, while
there are observed Cepheids with periods up to 210 days.


title:
Near-Infrared Spectroscopy of Very Low-Luminosity Young Stellar Objects
  in the Taurus Molecular Cloud

abstract:
  We have carried out near-infrared spectroscopic observations of 23 very
low-luminosity young stellar object (YSO) candidates and 5 their companions in
Heiles Cloud 2, one of the densest parts of the Taurus molecular cloud. Twelve
objects were confirmed as YSOs by Br gamma feature. The effective temperatures
of the YSOs and of the companions are estimated from the 2.26 micron feature,
the 2.21 micron feature, and the H2O band strengths. Detailed comparisons of
our photometric and spectroscopic observations with evolutionary tracks on the
HR diagram suggest some objects to be very low-mass YSOs.


title:
Chemical abundances of Damped Ly alpha systems: A new method for
  estimating dust depletion effects

abstract:
  A new method is presented for recovering the abundances of Damped Ly alpha
systems (DLAs) taking into account the effects of dust depletion. For the first
time, possible variations of the chemical composition of the dust are taken
into account in estimating the depletions. No prior assumptions on the
extinction properties of the dust are required. The method requires a set of
abundances measured in the gas and a set of parameters describing the chemical
properties of the dust. A large subset of these parameters is determined from
interstellar observations; the others are free parameters for which an educated
guess can be made. The method is able to recover the abundances of the SMC
starting from SMC interstellar measurements apparently discrepant from the
stellar ones. Application of the method to 22 DLAs with available [Fe/H] and
[Si/Fe] measurements gives the following results: (1) the mean metallicity of
the corrected data is <[Fe/H]> ~ -1.0 dex, about 0.5 dex higher than that of
the original data; (2) the slope of the [Fe/H] versus redshift relation is
steeper for the corrected data (m ~ -0.3 dex) than for the original ones (m ~
-0.2 dex); (3) the corrected [Si/Fe] ratios are less enhanced, on average, than
those found in Galactic stars of similar, low metallicity; (4) a decrease of
the [Si/Fe] versus [Fe/H] ratios, expected by "time delay" models of chemical
evolution, is found for the corrected data; (5) the [Si/Fe] ratios tend to
increase with redshift once corrected; (6) consistency between [Si/Fe] and
[S/Zn] measurements, two independent estimators of the alpha/Fe ratio, is found
only for the corrected abundances.


title: CSSs in a sample of B2 radio sources of intermediate strength

abstract:
  We present radio observations of 19 candidate compact steep-spectrum (CSS)
objects selected from a well-defined, complete sample of 52 B2 radio sources of
intermediate strength. These observations were made with the VLA A-array at
4.835 GHz. The radio structures of the entire sample are summarised and the
brightness asymmetries within the compact sources are compared with those of
the more extended ones, as well as with those in the 3CRR sample and the CSSs
from the B3-VLA sample. About 25 per cent of the CSS sources exhibit large
brightness asymmetries, with a flux density ratio for the opposing lobes of
$>$5, possibly due to interaction of the jets with infalling material. The
corresponding percentage for the larger-sized objects is only about 5 per cent.
We also investigate possible dependence of the flux density asymmetry of the
lobes on redshift, since this might be affected by more interactions and
mergers in the past. No such dependence is found. A few individual objects of
interest are discussed in the paper.


title: Distances and Other Parameters for 1315 Radio Pulsar

abstract:
  In this work we have collected observational data for 1315 PSRs. Distances
and others parameters for these PSRs were estimated. We present improved
distance estimates for radio pulsars by considering importance of their
physical properties and improvement of distribution of SFRs (star formation
regions) in the Galaxy. For this purpose, both a list of accurate calibrators
was constructed and several accurate criteria were established. The following
values were calculated from PSRs observational data: luminosities at 400 Mhz
and 1400 Mhz, characteristic times, strength of magnetic field and rate of
rotation energy. This compilation of data is mainly necessary for statistical
investigations and for the physical properties of neutron stars. The whole data
is prepared in a publicly accessible web page: http://www.xrbc.org/pulsar/ .


title: The acoustic spectrum of alpha Cen A

abstract:
  This paper presents the analysis of Doppler p-mode observations of the G2V
star $\alpha$ Cen A obtained with the spectrograph CORALIE in May 2001.
Thirteen nights of observations have made it possible to collect 1850 radial
velocity measurements with a standard deviation of about 1.5 m s$^{-1}$.
Twenty-eight oscillation modes have been identified in the power spectrum
between 1.8 and 2.9 mHz with amplitudes in the range 12 to 44 cm s$^{-1}$. The
average large and small spacing are respectively equal to 105.5 and 5.6
$\mu$Hz. A comparison with stellar models of $\alpha$ Cen A is presented.


title: Cosmic Flows: Review of Recent Developments

abstract:
  I review the recent developments in the analysis of cosmic flow data, in
particular, latest results of bulk flow measurements, comparison between
redshift and peculiar velocity catalogs with emphasis on the measured value of
the $\beta (=\Omega_m^{0.6}/b)$ parameter, and matter power spectrum estimates
from galaxy peculiar velocity catalogs. Based on these developments, one can
argue that most of the previous discrepancies in the interpretation of cosmic
flow data, {\it maybe} with the exception of bulk flow measurements on scales
$\gsim 100 h{^{-1}}{\rm Mpc}$, have either been resolved or fairly understood.


title: Observations of extragalactic masers in bright IRAS sources

abstract:
  We report the first results of an ongoing survey at 22 GHz with the 100-m
Effelsberg telescope to search for water maser emission in bright IRAS sources.
We have detected water vapor emission in IC 342. The maser, associated with a
star forming region ~10-15 arcsec west of the nucleus, consists of a single 0.5
km/s wide feature and reaches an isotropic luminosity of 0.01 L(sun) (D = 1.8
Mpc). Our detection raises the detection rate among northern galaxies with IRAS
point source fluxes S(100micron) > 50 Jy to 16%.


title: Future Perspectives at CERN

abstract:
  Current and future experiments at CERN are reviewed,with emphasis on those
relevant to astrophysics and cosmology. These include experiments related to
nuclear astrophysics, matter-antimatter asymmetry, dark matter, axions,
gravitational waves, cosmic rays, neutrino oscillations, inflation, neutron
stars and the quark-gluon plasma. The centrepiece of CERN's future programme is
the LHC, but some ideas for perspectives after the LHC are also presented.


title:
Near-Infrared photometry in the J, H and Kn bands for Polar Ring
  Galaxies: I. Data, structural parameters

abstract:
  We present new Near-Infrared (NIR) observations, in the J, H and Kn bands,
for a sample of Polar Ring Galaxies (PRGs), selected from the Polar Ring
Catalogue (Whitmore et al. 1990). Data were acquired with the CASPIR near-IR
camera at the 2.3 m telescope of Mount Stromlo and Siding Spring Observatory.
We report here on the detail morphological study for the central host galaxy
and the polar structure in all PRGs of our sample. Total magnitudes,
bulge-to-disk decomposition and structural parameters are computed for all
objects. These data are crucial for an accurate modeling of the stellar
population and the estimate of the star formation rates in the two components.


title: A Test of Photometric Redshifts for X-ray Selected Sources

abstract:
  We test the effectiveness of photometric redshifts based upon galaxy spectral
template fitting for X-ray luminous objects, using a sample of 65 sources
detected by Chandra in the field of the Caltech Faint Galaxy Redshift Survey
(CFGRS). We find that sources with quasar-dominated spectra (for which galaxy
spectral templates are not appropriate) are easily identified, and that
photometric redshifts are robust for the rest of the sources in our sample.
Specifically, for the 59 sources that are not quasar-dominated at optical
wavelengths, we find that the photometric redshift estimates have scatter
comparable to the field galaxy population in this region. There is no evidence
for a trend of increasing dispersion with X-ray luminosity over the range L_X =
10^39 - 5x10^43 erg/s, nor is there a trend with the ratio of X-ray to optical
flux, f_X/f_R. The practical implication of this work is that photometric
redshifts should be robust for the majority (~90%) of the X-ray sources down to
f_X ~ 10^-16 erg/s/cm^2 that have optical counterparts brighter than R ~ 24.
Furthermore, the same photometry can be easily used to identify the sources for
which the photometric redshifts are likely to fail. Photometric redshift
estimation can thus be utilized as an efficient tool in analyzing the
statistical properties of upcoming large Chandra and XMM-Newton data sets and
identifying interesting subsamples for further study.


title:
Near-Infrared photometry in the J, H and Kn bands for Polar Ring
  Galaxies: II. Global Properties

abstract:
  We discuss the properties of the host galaxy and ring light distributions in
the optical and near infrared bands for a sample of Polar Ring Galaxies (PRGs),
presented in Paper I (Iodice et al. 2002, Paper I). The goal of this work is to
test different formation scenarios for PRGs, proposed by different authors in
the last decades, by comparing their predictions with these new data. The
strategy is twofold: i) the integrated colors of the main components in these
systems are compared with those of standard morphological galaxy types, to
investigate whether differences in colors are caused by dust absorption or
difference in stellar populations. We then derived an estimate of the stellar
population ages in PRGs, which can be used to set constrains on the dynamical
modeling and the time evolution of these systems; ii) we analyse the structural
parameters of the host galaxy in order to understand whether this component is
a standard early-type system as its morphology suggests, and the light
distribution in the polar ring to measure its radial extension. These
observational results indicate that the global properties of PRGs are better
explained by dissipative merging of disks with un-equal masses as proposed by
Bekki (1998), rather than the accretion-or stripping-of gas by a pre-existing
early-type galaxy.


title: 12CO mapping of the low-metallicity BCD galaxy Mrk86

abstract:
  We have mapped the 12CO J=1-0 and J=2-1 line emission in Mrk86, one of the
most metal-deficient Blue Compact Dwarf galaxies so far detected in 12CO. The
12CO emission is distributed in a horseshoe-like structure that follows the
locus of the most recent star formation regions. The minimum in molecular-line
emission corresponds to the position of an older, massive nuclear starburst.
The H2 mass of the galaxy (in the range 0.4-5x10^7 Msun) and its morphology
have been compared with the predictions of hydrodynamic simulations of the
evolution of the interstellar medium surrounding a nuclear starburst. These
simulations suggest that the physical conditions in the gas swept out by the
starburst could have led to the formation of the ring of molecular gas reported
here. This result provides an attractive scenario for explaining the
propagation (in a galactic scale) of the star formation in dwarf galaxies.


title: Io revealed in the Jovian dust streams

abstract:
  The Jovian dust streams are high-speed bursts of submicron-sized particles
traveling in the same direction from a source in the Jovian system. Since their
discovery in 1992, they have been observed by three spacecraft: Ulysses,
Galileo and Cassini. The source of the Jovian dust streams is dust from Io's
volcanoes. The charged and traveling dust stream particles have particular
signatures in frequency space and in real space. The frequency-transformed
Galileo dust stream measurements show different signatures, varying
orbit-to-orbit during Galileo's first 29 orbits around Jupiter. Time-frequency
analysis demonstrates that Io is a localized source of charged dust particles.
Aspects of the particles' dynamics can be seen in the December-2000 joint
Galileo-Cassini dust stream measurements. To match the travel times, the
smallest dust particles could have the following range of parameters: radius:
6nm, density: 1.35-1.75gr/cm$^3$, sulfur charging conditions, which produce
dust stream speeds: 220|450km/sec (Galileo|Cassini) and charge potentials:
5.5|6.3Volt (Galileo|Cassini).


title:
CCD uvby-beta photometry of young open clusters. I. The double cluster h
  and chi Persei

abstract:
  We present CCD uvby-beta photometry for stars in the nuclei of the young
double cluster h and chi Persei. We find that the reddening is highly variable
through the h Persei nucleus, increasing from west to east, with values ranging
from E(b-y)=0.328+-0.022 in the western part to E(b-y)=0.465+-0.025 in the
south-east. Towards chi Persei the reddening is fairly constant, with
E(b-y)=0.398+-0.025. Both clusters share a common distance modulus of 11.7+-0.1
mag., and an age of log t=7.10+-0.05 years.


title:
Shear-Driven Field-Line Opening and the Loss of a Force-Free
  Magnetostatic Equilibrium

abstract:
  This paper discusses a quasi-static evolution of a force-free magnetic field
under slow sheared footpoint motions on the plasma's boundary, an important
problem with applications to the solar and accretion disk coronae. The main
qualitative features of the evolution (such as field-line expansion and
opening) are considered and a comparison is made between two different
geometrical settings: the Cartesian case with translational symmetry along a
straight line, and the axisymmetric case with axial symmetry around the
rotation axis. The main question addressed in the paper is whether a continuous
sequence of force-free equilibria describes the evolution at arbitrarily large
values of the footpoint displacement or the sequence ends abruptly and the
system exhibits a loss of equilibrium at a finite footpoint displacement. After
a formal description of the problem, a review/discussion of the extensive
previous work on the subject is given. After that, a series of simple
scaling-type arguments, explaining the key essential reason for the main
qualitative difference between the two geometry types, is presented. It is
found that, in the Cartesian case, force-free equilibria exist at arbitrarily
large values of shear and the field approaches the open state only at infinite
shear, whereas in the axisymmetric case the field opens up already at a finite
shear.


title: Classification and redshift estimation by principal component analysis

abstract:
  We show that the first 10 eigencomponents of the Karhunen-Lo\`eve expansion
or Principal Component Analysis (PCA) provide a robust classification scheme
for the identification of stars, galaxies and quasi-stellar objects from
multi-band photometry. To quantify the efficiency of the method, realistic
simulations are performed which match the planned Large Zenith Telescope
survey. This survey is expected to provide spectral energy distributions with a
resolution $R\simeq40$ for $\sim10^6$ galaxies to $R\le23$ ($z\sim 1$), $\sim
10^4$ QSOs, and $\sim 10^5$ stars.
  We calculate that for a median signal-to-noise ratio of 6, 98% of stars, 100%
of galaxies and 93% of QSOs are correctly classified. These values increase to
100% of stars, 100% of galaxies and 100% of QSOs at a median signal-to-noise
ratio of 10. The 10-component PCA also allows measurement of redshifts with an
accuracy of $\sigma_\mathrm{Res.}\la0.05$ for galaxies with $z\la0.7$, and to
$\sigma_\mathrm{Res.}\la0.2$ for QSOs with $z\ga2$, at a median signal-to-noise
ratio of 6. At a median signal-to-noise ratio 20, $\sigma_\mathrm{Res.}\la0.02$
for galaxies with $z\la1$ and for QSOs with $z\ga2.5$ (note that for a median
$S/N$ ratio of 20, the bluest/reddest objects will have a signal-to-noise ratio
of $\la 2$ in their reddest/bluest filters). This redshift accuracy is inherent
to the $R\simeq40$ resolution provided by the set of medium-band filters used
by the Large Zenith Telescope survey. It provides an accuracy improvement of
nearly an order of magnitude over the photometric redshifts obtained from
broad-band $BVRI$ photometry.


title: Compton Scattered Transition Radiation from Very High Energy Particles

abstract:
  X-ray transition radiation can be used to measure the Lorentz factor of
relativistic particles. At energies approaching gamma = E/mc^2 = 10^5,
transition radiation detectors (TRDs) can be optimized by using thick (sim 5 -
10 mil) foils with large (5-10 mm) spacings. This implies X-ray energies >100
keV and the use of scintillators as the X-ray detectors. Compton scattering of
the X-rays out of the particle beam then becomes an important effect. We
discuss the design of very high energy detectors, the use of metal radiator
foils rather than the standard plastic foils, inorganic scintillators for
detecting Compton scattered transition radiation, and the application to the
ACCESS cosmic ray experiment.


title: Arcsecond Images of CH3CN Toward W75N

abstract:
  CH3CN (J=6-5) was observed with a resolution of 2'' toward W75N using the
BIMA interferometer. Two continuum sources were detected at 3 mm, designated
MM1 and MM2 in previous studies. Alignment of two mm continuum sources with the
outflow axis from MM1 suggests that these continuum sources may be the result
of the outflow interacting with the interstellar medium. MM1 is coincident with
compact CH3CN emission. CH3CN was not detected toward MM2. The distribution of
optical depth is derived. An excitation analysis was not done because of large
line optical depths.


title:
Resolving the Effects of Resonant X-ray Line Scattering in Cen X-3 with
  Chandra

abstract:
  The massive X-ray binary Cen X-3 was observed over approximately one quarter
of the system's 2.08 day orbit, beginning before eclipse and ending slightly
after eclipse center with the Chandra X-ray Observatory using its High-Energy
Transmission Grating Spectrometer. The spectra show K shell emission lines from
hydrogen- and helium-like ions of magnesium, silicon, sulfur, and iron as well
as a K-alpha fluorescence emission feature from near-neutral iron. The
helium-like n=2->1 triplet of silicon is fully resolved and the analogous
triplet of iron is partially resolved. The helium-like triplet component flux
ratios outside of eclipse are consistent with emission from recombination and
subsequent cascades (recombination radiation) from a photoionized plasma. In
eclipse, however, the w (resonance) lines of silicon and iron are stronger than
that expected for recombination radiation, and are consistent with emission
from a collisionally ionized plasma. The triplet line flux ratios at both
phases can be explained more naturally, however, as emission from a
photoionized plasma if the effects of resonant line scattering are included in
addition to recombination radiation. We show that the emissivity due to
resonant scattering depends sensitively on the line optical depth and, in the
case of winds in X-ray binaries, this allows constraints on the wind velocity
even when Doppler shifts cannot be resolved.


title:
Rotation of stars in NGC 6134: a comparison of Delta Scuti stars and
  non-variable stars

abstract:
  We present results of spectroscopic observations of selected stars in the
southern open cluster NGC 6134. We have determined the rotational velocities of
the six known Delta Scuti Stars in NGC 6134 as well as several other
non-variable stars with similar colour temperature in order to investigate if v
sin i and variability is somehow connected: we find no such correlation. We
also compare the distribution of v sin i of Delta Scuti Stars and non-variable
stars with four other well-studied open clusters to look for any systematic
behaviour, but we find no conclusive evidence for v sin i and variability to be
connected. We have also used the spectra to carry out an abundance analysis of
the Delta Scuti Stars in NGC 6134 to confirm the high metal content of the
cluster. We find [Fe/H] = +0.38 +/- 0.05 which is in agreement with the result
obtained from Stromgren photometry. We also present Delta-a photometry of the
cluster, but we find no chemical peculiar stars based on this index.


title:
Rebirth of Novae as Distance Indicators Due to Efficient Large
  Telescopes

abstract:
  Nova outbursts are the result of strong thermonuclear runaways on the surface
of a white dwarf accreting Hydrogen-rich material from a small mass companion.
These giant explosions cause the star to increase its brightness by hundreds of
thousands of times then making these objects powerful standard candles useful
to measure the extragalactic distances.We have used the Very Large Telescope,
located in the Chilean Atacama desert, to search for novae in NGC 1316--an
early type galaxy in the Fornax cluster. We discovered 4 novae with 3h of
observing time. The use of 8-10m class telescopes coupled with new detectors,
can dramatically improve the efficiency of nova searches in extragalactic
systems.


title: Weak Lensing Probes of the Galaxy-Mass Cross Power Spectrum

abstract:
  The angular correlation function of the background shear-foreground galaxy
distribution probes the three dimensional cross power spectrum between mass and
galaxies. The same cross power spectrum is also probed when foreground galaxy
distribution is cross-correlated with a distribution of background sources
disjoint in redshift space. The kernels that project three dimensional
clustering to the two dimensional angular space is different for these two
probes. When combined, they allow a study of the galaxy-mass cross power
spectrum from linear to non-linear scales. By inverting the background
shear-foreground galaxy correlation function measured by the Sloan Digital Sky
Survey, we present a first estimate of the cross power spectrum between mass
and galaxies at low redshifts.


title:
Polarimetric variations of binary stars. IV. Pre-main-sequence
  spectroscopic binaries located in Taurus, Auriga, and Orion

abstract:
  We present polarimetric observations of 14 pre-main-sequence (PMS) binaries
located in the Taurus, Auriga, and Orion star forming regions. The majority of
the average observed polarizations are below 0.5%, and none are above 0.9%.
After removal of estimates of the interstellar polarization, about half the
binaries have an intrinsic polarization above 0.5%, even though most of them do
not present other evidences for the presence of circumstellar dust. Various
tests reveal that 77% of the PMS binaries have or possibly have a variable
polarization. LkCa3, Par1540, and Par2494 present detectable periodic and
phase-locked variations. The periodic polarimetric variations are noisier and
of a lesser amplitude (~0.1%) than for other types of binaries, such as hot
stars. This could be due to stochastic events that produce deviations in the
average polarization, a non-favorable geometry (circumbinary envelope), or the
nature of the scatterers (dust grains are less efficient polarizers than
electrons). Par1540 is a Weak-line TTauri Star, but nonetheless has enough dust
in its environment to produce detectable levels of polarization and variations.
A fourth interesting case is W134, which displays rapid changes in polarization
that could be due to eclipses. We compare the observations with some of our
numerical simulations, and also show that an analysis of the periodic
polarimetric variations with the Brown, McLean, & Emslie (BME) formalism to
find the orbital inclination is for the moment premature: non-periodic events
introduce stochastic noise that partially masks the periodic low-amplitude
variations and prevents the BME formalism from finding a reasonable estimate of
the orbital inclination.


title: A Scattered Light Echo around SN 1993J in M81

abstract:
  A light echo around SN 1993J was observed 8.2 years after explosion by a HST
WFPC2 observation, adding to the small family of supernovae with light echoes.
The light echo was formed by supernova light scattered from a dust sheet, which
lies 220 parsecs away from the supernova, 50 parsecs thick along the line of
sight, as inferred from radius and width of the light echo. The dust inferred
from the light echo surface brightness is 1000 times denser than the intercloud
dust. The graphite to silicate fraction can not be determined by our BVI
photometric measurements, however, a pure graphite model can be excluded based
on comparison with the data. With future observations, it will be possible to
measure the expansion rate of the light echo, from which an independent
distance to M81 can be obtained.


title: Extreme X-ray Iron Lines in Active Galactic Nuclei

abstract:
  We analyze X-ray spectra of heavily obscured (N_H > 10^{24} cm^{-2}) active
galaxies obtained with Chandra, concentrating on the iron K alpha fluorescence
line. We measure very large equivalent widths in most cases, up to 5 keV in the
most extreme example. The geometry of an obscuring torus of material near the
active galactic nucleus (AGN) determines the Fe emission, which we model as a
function of torus opening angle, viewing angle, and optical depth. The
starburst/AGN composite galaxies in this sample require small opening angles.
Starburst/AGN composite galaxies in general therefore present few direct lines
of sight to their central engines. These composite galaxies are common, and
their large covering fractions and heavy obscuration effectively hide their
intrinsically bright X-ray continua. While few distant obscured AGNs have been
identified, we propose to exploit their signature large Fe K alpha equivalent
widths to find more examples in X-ray surveys.


title:
A Comprehensive Study of Pulse Profile Evolution in SGR 1806-20 & SGR
  1900+14 with the RXTE PCA

abstract:
  Soft Gamma Repeaters undergo pulse profile changes in connection with their
burst activity. Here we present a comprehensive pulse profile history of SGR
1806-20 and SGR 1900+14 in three energy bands using Rossi X-ray Timing
Explorer/Proportional Counter Array observations performed between 1996 and
2001. Using the Fourier harmonic powers of pulse profiles, we quantify the
pulse shape evolution. Moreover, we determined the RMS pulsed count rates
(PCRs) of each profile. We show that the pulse profiles of SGR 1806$-$20 remain
single pulsed showing only modest changes for most of our observing span, while
those of SGR 1900+14 change remarkably in all energy bands. Highly significant
pulsations from SGR 1900+14 following the 1998 August 27 and 2001 April 18
bursts enabled us to study not only the decay of PCRs in different energy bands
but also their correlations with each other.


title:
Statistical Re-examination of Reported Emission Lines in the X-ray
  Afterglow of GRB 011211

abstract:
  (abridged) A 0.2-12 keV spectrum obtained with the XMM EPIC/pn instrument of
GRB 011211 was found by Reeves et al. (2002) to contain emission lines which
were interpreted to be from Mg XI, Si XIV, S XVI, Ar XVIII, and Ca XX, at a
lower redshift (z_{obs}=1.88) than the host galaxy (z_{host}=2.14). We examine
the spectrum independently, and find that the claimed lines would not be
discovered in a blind search. Specifically, Monte Carlo simulations show that
they would be observed in 10% of featureless spectra with the same
signal-to-noise. Imposing a model in which the two brightest lines would be Si
XIV and S XVI K-alpha emission possibly velocity shifted to between
z=1.88--2.40, such features would be found in between ~1.2-2.6% of observed
featureless spectra. We find the detection significances to be insufficient to
justify the claim of detection and the model put forth to explain them. K-alpha
line complexes are also found at z=1.2 and z=2.75 of significance equal to or
greater than that at z=1.88. If one adopts the z=1.88 complex as significant,
one must also adopt the other two complexes to be significant. The
interpretation of these data in the context of the model proposed by Reeves et
al. is therefore degenerate, and cannot be resolved by these data alone.


title: Search for QSO candidates in OGLE-II data

abstract:
  A search for faint slowly variable objects was undertaken in the hope of
finding QSO candidates behind the Small and Large Magellanic Clouds (SMC and
LMC). This search used the optical variability properties of point sources from
the Magellanic cloud OGLE-II photometric data. Objects bluer than V-I=0.9 and
within 17 < I < 20.5 were studied. Robust variograms/structure functions have
been computed for each time-series and only candidates showing a significant
increasing variability over longer time scales were selected.
  Several light curves were identified as having probable artifacts and were
therefore removed. Stars showing signs of periodicity or small trends in their
light curves were also removed and we are left with mostly either Be stars
(gamma Cas stars) or QSO candidates.
  We present a list of 25 slowly varying objects for SMC and 155 for LMC, out
of 15'000 and 53'000 variable objects respectively. Of these, about 15 objects
for the SMC and 118 objects for the LMC are QSO candidates.


title: Sulphur abundances in disk stars: a correlation with silicon

abstract:
  We have performed new determinations of sulphur and silicon abundances for a
sample of 26 disk stars based on high-resolution, high signal-to-noise spectra.
The results indicate a solar [S/Fe] for [Fe/H] >-0.3, below which [S/Fe]
increases to ~0.25 dex at [Fe/H] =-1.0. We find that there is a good
correlation between [S/H] and [Si/H], indicating the same nucleosynthetic
origin of the two elements. It seems that the ratio of sulphur to silicon does
not depend on metallicity for [Fe/H]> -1.0. The implications of these results
on models for the nucleosynthesis of alpha-capture elements and the chemical
evolution of the Galaxy are discussed.


title:
Limit shocks of relativistic magnetohydrodynamics, Punsly's waveguide
  and the Blandford-Znajek solution

abstract:
  In this paper we examine various issues closely related to the ongoing
discussion on the nature of the Blandford-Znajek mechanism of extraction of
rotational energy of black holes. In particular, we show that switch-on and
switch-off shocks are allowed by the shock equations of relativistic MHD and
have similar properties to their Newtonian counterparts. Just like in Newtonian
MHD they are limits of fast and slow shock solutions and as such they may be
classified as weakly evolutionary shocks. The analysis of Punsly's MHD
waveguide problem shows that its solution cannot have the form of a traveling
step wave and that both fast and Alfv\'en waves are essential for generating
the flow in the guide. Causality considerations are used to argue that the
Blandford-Znajek perturbative solution is in conflict with the membrane
paradigm. An alternative interpretation is presented according to which the
role of an effective unipolar inductor in the Blandford-Znajek mechanism is
played by the ergospheric region of a rotating black hole. Various implications
of this are discussed.


title:
NH3 in the Central 10 pc of the Galaxy. II. Determination of Opacity for
  Gas with Large Linewidths

abstract:
  The 23 GHz emission lines from the NH3 rotation inversion transitions are
widely used to investigate the kinematics and physical conditions in dense
molecular clouds. The line profile is composed of hyperfine components which
can be used to calculate the opacity of the gas (Ho & Townes 1983). If the
intrinsic linewidth of the gas exceeds one half of the separation of these
quadrupole hyperfine components (~5-10 km/s) these lines blend together and the
observed linewidths greatly overestimate the intrinsic linewidths. If
uncorrected, these artificially broad linewidths will lead to artificially high
opacities. We have observed this effect in our NH3 data from the central 10 pc
of the Galaxy where uncorrected NH3 (1,1) linewidths of ~30 km/s exaggerate the
intrinsic linewidths by more than a factor of two (Genzel & Townes 1987).
Models of the effect of blending on the line profile enable us to solve for the
intrinsic linewidth and opacity of NH3 using the observed linewidth and
intensity of two NH3 rotation inversion transitions. We present the result of
the application of this method to our Galactic Center data. We successfully
recover the intrinsic linewidth and opacity of the gas. Clouds close to the
nucleus in projected distance as well as those that are being impacted by Sgr A
East show the highest intrinsic linewidths. The cores of the ``southern
streamer'' (Ho et al. 1991; Coil & Ho 1999, 2000) and the ``50 km/s'' giant
molecular cloud have the highest opacities.


title:
Probing the mass loss history of carbon stars using CO line and dust
  continuum emission

abstract:
  An extensive modelling of CO line emission from the circumstellar envelopes
around a number of carbon stars is performed. By combining radio observations
and infrared observations obtained by ISO the circumstellar envelope
characteristics are probed over a large radial range. In the radiative transfer
analysis the observational data are consistently reproduced assuming a
spherically symmetric and smooth wind expanding at a constant velocity. The
combined data set gives better determined envelope parameters, and puts
constraints on the mass loss history of these carbon stars. The importance of
dust in the excitation of CO is addressed using a radiative transfer analysis
of the observed continuum emission, and it is found to have only minor effects
on the derived line intensities. The analysis of the dust emission also puts
further constraints on the mass loss rate history. The stars presented here are
not likely to have experienced any drastic long-term mass loss rate
modulations, at least less than a factor of about 5, over the past thousands of
years. Only three, out of nine, carbon stars were observed long enough by ISO
to allow a detection of CO far-infrared rotational lines.


title: Sunyaev-Zeldovich Effect from Quasar-driven Blast-waves

abstract:
  Quasar-driven winds are currently the best candidates for accounting for the
pre-heating of the intergalactic medium in clusters. Such winds, occurring
during early phases of the evolution of spheroidal galaxies, shock-heat the
interstellar gas, thus inducing a detectable Sunyaev-Zeldovich effect. We
estimate the amplitude and the angular scale of such effect as well as its
counts as a function of the comptonization parameter $y$. The contamination due
to radio emission by the quasar itself is also discussed. The corresponding
mean Compton distortion of the cosmic microwave background spectrum is found to
be well below the COBE/FIRAS upper limit.


title:
Detection of the Neupert Effect in the Corona of an RS CVn Binary System
  by XMM-Newton and the VLA

abstract:
  The RS CVn-type binary $\sigma$ Geminorum was observed during a large,
long-duration flare simultaneously with {\it XMM-Newton} and the VLA. The light
curves show a characteristic time dependence that is compatible with the
Neupert effect observed in solar flares: The time derivative of the X-ray light
curve resembles the radio light curve. This observation can be interpreted in
terms of a standard flare scenario in which accelerated coronal electrons reach
the chromosphere where they heat the cool plasma and induce chromospheric
evaporation. Such a scenario can only hold if the amount of energy in the fast
electrons is sufficient to explain the X-ray radiative losses. We present a
plausibility analysis that supports the chromospheric evaporation model.


title:
High resolution spatial and timing observations of millisecond pulsar
  PSR J0218+4232 with Chandra

abstract:
  We report on high-resolution spatial and timing results for binary
millisecond pulsar PSR J0218+4232 obtained with the Chandra HRC-I and HRC-S in
imaging mode. We found no indications for extended emission at 1 arcsec scales.
With the HRC-S observation we obtained a 0.08-10 keV pulse profile with high
statistics which could be compared in absolute time with the pulse profiles at
radio-frequencies and at high-energy gamma-rays. The two X-ray pulses at
aligned with 2 of the 3 radio-pulses, and with the 2 gamma-ray pulses.


title: Cosmological constraints from evaporations of primordial black holes

abstract:
  The formula for the initial mass spectrum of primordial black holes (PBHs),
which can be used for a general case of the scale dependent spectral index, and
for a wide class of models of the gravitational collapse, is derived. The
derivation is based on the Press and Schechter formalism. The comparative
analysis of different types of initial mass spectra used in concrete
calculations is carried out. It is shown that densities of background
radiations ($\nu$, $\gamma$) from PBH evaporations depend rather strongly on a
type of the gravitational collapse and on a taking into account the spread of
horizon masses at which PBHs can form. Constraints on parameters of the
primordial density perturbation amplitudes based on PBH evaporation processes
and on atmospheric and solar neutrino data are obtained.


title:
Pulsating or not? A search for hidden pulsations below the red edge of
  the ZZ instability strip

abstract:
  The location of the red edge of the ZZ Ceti instability strip is defined
observationally as being the lowest temperature for which a white dwarf with a
H-rich atmosphere (DA) is known to exhibit periodic brightness variations.
Whether this cut-off in flux variations is actually due to a cessation of
pulsation or merely due to the attenuation of any variations by the convection
zone, rendering them invisible, is not clear. The latter is a theoretical
possibility because with decreasing effective temperature, the emergent flux
variations become an ever smaller fraction of the amplitude of the flux
variations in the interior. In contrast to the flux variations, the visibility
of the velocity variations associated with the pulsations is not thought to be
similarly affected. Thus, models imply that were it still pulsating, a white
dwarf just below the observed red edge should show velocity variations. In
order to test this possibility, we used time-resolved spectra of three DA white
dwarfs that do not show photometric variability, but which have derived
temperatures only slightly lower than the coolest ZZ Ceti variables. We find
that none of our three targets show significant periodic velocity variations,
and set 95% confidence limits on amplitudes of 3.0, 5.2, and 8.8km/s. Thus, for
two out of our three objects, we can rule out velocity variations as large as
5.4km/s observed for the strongest mode in the cool white dwarf pulsator ZZ
Psc. In order to verify our procedures, we also examined similar data of a
known ZZ Ceti, HL Tau 76. Applying external information from the light curve,
we detect significant velocity variations for this object with amplitudes of up
to 4km/s, making it only the third DAV for which velocity variations have been
measured. (abridged)


title:
Time delay and lens redshift for the doubly imaged BAL quasar
  SBS1520+530

abstract:
  We present optical R-band light curves of the gravitationally lensed quasar
SBS1520+530 derived from data obtained at the Nordic Optical Telescope. A time
delay of 130+/-3 days (1 sigma) is determined from the light curves. In
addition, spectra of SBS1520+530 obtained at the Keck Observatory are spatially
deconvolved in order to extract the spectrum of the faint lensing galaxy, free
of any contamination by the light from the bright quasar images. This spectrum
indicates a lens redshift z=0.717, in agreement with one of the absorption
systems found in the quasar spectra. The best mass model of the system includes
a second nearby galaxy and a cluster of galaxies in addition to the main
lensing galaxy. Adopting this model and an Omega=0.3, Lambda=0.7 cosmology, our
time-delay measurement yields a Hubble constant of H_0=51+/- 9, km/s/Mpc (1
sigma error).


title:
Statistical methods of automatic spectral classification and their
  application to the Hamburg/ESO Survey

abstract:
  We employ classical statistical methods of multivariate classification for
the exploitation of the stellar content of the Hamburg/ESO objective prism
survey (HES). In a simulation study we investigate the precision of a
three-dimensional classification (Teff, log g, [Fe/H]) achievable in the HES
for stars in the effective temperature range 5200<Teff<6800K, using Bayes
classification. The accuracy in temperature determination is better than 400K
for HES spectra with S/N>10 (typically corresponding to B_J<16.5). The
accuracies in log g and [Fe/H] are better than 0.68dex in the same S/N range.
These precisions allow for a very efficient selection of metal-poor stars in
the HES. We present a minimum cost rule for compilation of complete samples of
objects of a given class, and a rejection rule for identification of corrupted
or peculiar spectra. The algorithms we present are being used for the
identification of other interesting objects in the HES data base as well, and
they are applicable to other existing and future large data sets, such as those
to be compiled by the DIVA and GAIA missions.


title:
A Search for Disk Emission in Young Brown Dwarfs: L'-band Observations
  of sigma Orionis and TW Hydrae

abstract:
  Studies of disks around young brown dwarfs are of paramount importance to our
understanding of the origin, diversity and early evolution of sub-stellar
objects. Here we present first results from a systematic search for disk
emission in a spectroscopically confirmed sample of young objects near or below
the sub-stellar boundary in a variety of star-forming regions. Our VLT and Keck
L'-band observations of the sigma Orionis and TW Hydrae associations suggest
that if a majority of brown dwarfs are born with disks, at least the inner
regions of those disks evolve rapidly, possibly clearing out within a few
million years.


title: Discovery of High-Latitude CO in a HI Supershell in NGC 5775

abstract:
  We report the discovery of very high latitude molecular gas in the edge-on
spiral galaxy, NGC 5775. Emission from both the J=1-0 and 2-1 lines of 12CO is
detected up to 4.8 kpc away from the mid-plane of the galaxy. NGC 5775 is known
to host a number of HI supershells. The association of the molecular gas
M(H2,F2) = 3.1x10^7 solar masses reported here with one of the HI supershells
(labeled F2) is clear, which suggests that molecular gas may have survived the
process which originally formed the supershell. Alternatively, part of the gas
could have been formed in situ at high latitude from shock-compression of
pre-existing HI gas. The CO J=2-1/J=1-0 line ratio of 0.34+-40% is
significantly lower than unity, which suggests that the gas is excited
subthermally, with gas density a few times 100 cubic cm. The molecular gas is
likely in the form of cloudlets which are confined by magnetic and cosmic rays
pressure. The potential energy of the gas at high latitude is found to be
2x10^56 ergs and the total (HI + H2) kinetic energy is 9x10^53 ergs. Based on
the energetics of the supershell, we suggest that most of the energy in the
supershell is in the form of potential energy and that the supershell is on the
verge of falling and returning the gas to the disk of the galaxy.


title: Interpreting Offsets from the Tully-Fisher Relation

abstract:
  We have previously demonstrated that Tully-Fisher residuals correlate with
tracers of star formation history (color and emission line equivalent width)
for a broad sample of Sa--Sd spiral galaxies (Kannappan, Fabricant, & Franx
2002). Here we use these correlations to study two other classes of galaxies:
(1) galaxies in close pairs and (2) galaxies at intermediate redshift.


title: A Reappraisal of the Solar Photospheric C/O Ratio

abstract:
  Accurate determination of photospheric solar abundances requires detailed
modeling of the solar granulation and accounting for departures from local
thermodynamical equilibrium (LTE). We argue that the forbidden C I line at 8727
A is largely immune to departures from LTE, and can be realistically modeled
using LTE radiative transfer in a time-dependent three-dimensional simulation
of solar surface convection. We analyze the [C I] line in the solar flux
spectrum to derive the abundance log epsilon(C)= 8.39 +/- 0.04 dex. Combining
this result with our parallel analysis of the [O I] 6300 A line, we find
C/O=0.50 +/- 0.07, in agreement with the ratios measured in the solar corona
from gamma-ray spectroscopy and solar energetic particles.


title: Measuring starspots on magnetically active stars with the VLTI

abstract:
  We present feasibility studies to directly image stellar surface features,
which are caused by magnetic activity, with the Very Large Telescope
Interferometer (VLTI). We concentrate on late type magnetically active stars,
for which the distribution of starspots on the surface has been inferred from
photometric and spectroscopic imaging analysis. The study of the surface spot
evolution during consecutive rotation cycles will allow first direct
measurements (apart from the Sun) of differential rotation which is the central
ingredient of magnetic dynamo processes. The VLTI will provide baselines of up
to 200 m, and two scientific instruments for interferometric studies at near-
and mid-infrared wavelengths. Imaging capabilities will be made possible by
closure-phase techniques. We conclude that a realistically modeled cool surface
spot can be detected on stars with angular diameters exceeding ~2 mas using the
VLTI with the first generation instrument AMBER. The spot parameters can then
be derived with reasonable accuracy. We discuss that the lack of knowledge of
magnetically active stars of the required angular size, especially in the
southern hemisphere, is a current limitation for VLTI observations of these
surface features.


title:
A catalogue of damped Lyman alpha absorption systems and radio flux
  densities of the background quasars

abstract:
  We present a catalogue of the 322 damped Lyman alpha absorbers taken from the
literature. All damped Lyman alpha absorbers are included, with no selection on
redshift or quasar magnitude. Of these, 123 are candidates and await
confirmation using high resolution spectroscopy. For all 322 objects we
catalogue the radio properties of the background quasars, where known. Around
60 quasars have radio flux densities above 0.1 Jy and approximately half of
these have optical magnitudes brighter than V = 18. This compilation should
prove useful in several areas of extragalactic/cosmological research.


title:
Testing Stellar Population Models with Star Clusters in the Large
  Magellanic Cloud

abstract:
  We present high S/N integrated spectra of 24 star clusters in the LMC
obtained using the FLAIR spectrograph at the UK Schmidt. The spectra have been
placed onto the Lick/IDS system in order to test the calibration of Simple
Stellar Population (SSP) models. We have compared the SSP-predicted
metallicities of the clusters with literature Ca-Triplet values, and find that
there is good agreement in the range --2.10 < [Fe/H] < 0. However, the
magnesium indices systematically predict higher metallicities than iron, among
the possible explanations for this are that the LMC clusters possess [alpha/Fe]
> 0. We present metallicities for 11 clusters with no previous measurements.
Comparison of the SSP ages of the clusters (from Balmer lines) with the
literature data shows good agreement for the majority. This includes six old
globular clusters in our sample, which have ages consistent with their HST CMD
turn-offs. However, two clusters, NGC 1754 and NGC 2005, have Hbeta
line-strengths which lead to ages which are too young (~8 and ~6 Gyr
respectively at 3 sigma) for their HST CMDs. Comparison between the horizontal
branch (HB) morphology and Balmer lines of these clusters suggests that blue
HBs have increased their Balmer indices by up to ~1.0 angstrom. We conclude
that the Lick/IDS indices, used in conjunction with contemporary SSP models,
are able to reproduce the ages and metallicities of the LMC clusters
reassuringly well. However, SSP model ages derived for metal-poor globular
clusters are ambiguous without a priori knowledge of HB morphology (abridged).


title: 1/f noise and other systematic effects in the Planck-LFI radiometers

abstract:
  We use an analytic approach to study the susceptibility of the Planck Low
Frequency Instrument radiometers to various systematic effects. We examine the
effects of fluctuations in amplifier gain, in amplifier noise temperature and
in the reference load temperature. We also study the effect of imperfect gain
modulation, non-ideal matching of radiometer parameters, imperfect isolation in
the two legs of the radiometer and back-end 1/f noise. We find that with proper
gain modulation 1/f gain fluctuations are suppressed, leaving fluctuations in
amplifier noise temperature as the main source of 1/f noise. We estimate that
with a gain modulation factor within +- 1% of its ideal value the overall 1/f
knee frequency will be relatively small (< 0.1 Hz).


title: The intermediate-age open cluster NGC 2112

abstract:
  We report on $BVI$ CCD photometry of a field centered on the region of the
intermediate-age open cluster NGC 2112 down to V=21. Due to the smaller field
coverage, we are able to limit the effect of field star contamination which
hampered in the past precise determinations of the cluster age and distance.
This way, we provide updated estimates of NGC 2112 fundamental parameters.
Having extended the photometry to the $I$ pass-band, we are able to construct a
colour-colour diagram, from which we infer a reddening $E_{B-V}= 0.63\pm0.14$
mag. The comparison of the Colour-Magnitude Diagram (CMD) with theoretical
isochrones leads to a distance of $850 \pm 100$ pc, and an age of $2.0 \pm 0.3$
Gyr. While the distance is in agreement with previous determinations, the age
turns out to be much better constrained and significantly lower than previous
estimates.


title: A long hard look at MCG-6-30-15 with XMM-Newton

abstract:
  We present first results from a 325 ks observation of the Seyfert 1 galaxy
MCG-6-30-15 with XMM-Newton and BeppoSAX. The strong, broad, skewed iron line
is clearly detected and is well characterised by a steep emissivity profile
within 6r_g (i.e. 6GM/c^2) and a flatter profile beyond. The inner radius of
the emission appears to lie at about 2r_g, consistent with results reported
from both an earlier XMM-Newton observation of MCG-6-30-15 by Wilms et al. and
part of an ASCA observation by Iwasawa et al. when the source was in a lower
flux state. The radius and steep emissivity profile do depend however on an
assumed incident power-law continuum and a lack of complex absorption above 2.5
keV. The blue wing of the line profile is indented, either by absorption at
about 6.7 keV or by a hydrogenic iron emission line. The broad iron line flux
does not follow the continuum variations in a simple manner.


title: Predicted FeII Emission-Line Strengths from Active Galactic Nuclei

abstract:
  We present theoretical FeII emission line strengths for physical conditions
typical of Active Galactic Nuclei with Broad-Line Regions. The FeII line
strengths were computed with a precise treatment of radiative transfer using
extensive and accurate atomic data from the Iron Project. Excitation mechanisms
for the FeII emission included continuum fluorescence, collisional excitation,
self-fluorescence amoung the FeII transitions, and fluorescent excitation by
Lyman-alpha and Lyman-beta. A large FeII atomic model consisting of 827 fine
structure levels (including states to E ~ 15 eV) was used to predict fluxes for
approximately 23,000 FeII transitions, covering most of the UV, optical, and IR
wavelengths of astrophysical interest. Spectral synthesis for wavelengths from
1600 Angstroms to 1.2 microns is presented. Applications of present theoretical
templates to the analysis of observations are described. In particular, we
discuss recent observations of near-IR FeII lines in the 8500 Angstrom -- 1
micron region which are predicted by the Lyman-alpha fluorescence mechanism. We
also compare our UV spectral synthesis with an empirical iron template for the
prototypical, narrow-line Seyfert galaxy I Zw 1. The theoretical FeII template
presented in this work should also applicable to a variety of objects with FeII
spectra formed under similar excitation conditions, such as supernovae and
symbiotic stars.


title: Luminosity profiles of advanced mergers of galaxies using 2MASS data

abstract:
  A sample of 27 disturbed galaxies that show signs of interaction but have a
single nucleus were selected from the Arp and the Arp-Madore catalogues. For
these, the K_s band images from the Two Micron All Sky Survey (2MASS) are
analysed to obtain their radial luminosity profiles and other structural
parameters. We find that in spite of their similar optical appearance, the
sample galaxies vary in their dynamical properties, and fall into two distinct
classes. The first class consists of galaxies which can be described by a
single r^{1/4} law and the second class consists of galaxies that show an outer
exponential disk. A few galaxies that have disturbed profiles cannot be fit
into either of the above classes. However, all the galaxies are similar in all
other parameters such as the far-infrared colours, the molecular hydrogen
content and the central velocity dispersion. Thus, the dynamical parameters of
these sets seem to be determined by the ratio of the initial masses of the
colliding galaxies. We propose that the galaxies in the first class result from
a merger of spiral galaxies of equal masses whereas the second class of
galaxies results from a merger of unequal mass galaxies. The few objects that
do not fall into either category show a disturbed luminosity profile and a
wandering centre, which is indicative of these being unrelaxed mergers. Of the
27 galaxies in our sample, 9 show elliptical-like profiles and 13 show an outer
exponential. Interestingly, Arp 224, the second oldest merger remnant of the
Toomre sequence shows an exponential disk in the outer parts.


title:
Intrinsic correlation of halo ellipticity and its implications for
  large-scale weak lensing surveys

abstract:
  We use a large set of state-of-the-art cosmological N-body simulations [512^3
particles] to study the intrinsic ellipticity correlation functions of halos.
With the simulations of different resolutions, we find that the ellipticity
correlations converge once the halos have more than 160 members. For halos with
fewer members, the correlations are underestimated, and the underestimation
amounts to a factor of 2 when the halos have only 20 particles. After
correcting for the resolution effects, we show that the ellipticity
correlations of halos in the bigger box (L=300 mpc) agree very well with those
obtained in the smaller box (L=100 mpc). Combining these results from the
different simulation boxes, we present accurate fitting formulae for the
ellipticity correlation function c_{11}(r) and for the projected correlation
functions Sigma_{11}(r_p) and Sigma_{22}(r_p) over three orders of magnitude in
halo mass. The latter two functions are useful for predicting the contribution
of the intrinsic correlations to deep lensing surveys. With reasonable
assumptions for the redshift distribution of galaxies and for the mass of
galaxies, we find that the intrinsic ellipticity correlation can contribute
significantly not only to shallow surveys but also to deep surveys. Our results
indicate that previous similar studies significantly underestimated this
contribution for their limited simulation resolutions.


title: A box-fitting algorithm in the search for periodic transits

abstract:
  We study the statistical characteristics of a box-fitting algorithm to
analyze stellar photometric time series in the search for periodic transits by
extrasolar planets. The algorithm searches for signals characterized by a
periodic alternation between two discrete levels, with much less time spent at
the lower level. We present numerical as well as analytical results to predict
the possible detection significance at various signal parameters. It is shown
that the crucial parameter is the effective signal-to-noise ratio -- the
expected depth of the transit divided by the standard deviation of the measured
photometric average within the transit. When this parameter exceeds the value
of 6 we can expect a significant detection of the transit. We show that the
box-fitting algorithm performs better than other methods available in the
astronomical literature, especially for low signal-to-noise ratios.


title: Far-red spectroscopy of peculiar stars and the GAIA mission

abstract:
  The coming GAIA Cornerstone mission by ESA will provide micro-arcsec
astrometry, 10 bands photometry and far-red spectroscopy for a huge number of
stars in the Galaxy (10^9). GAIA spectroscopy will cover the range 8480--8740
Ang, which includes the CaII triplet and the head of the Paschen series. In
this paper we address the diagnostic potential of this wavelength range toward
detection and characterization of peculiar stars.


title: High-energy radiation from pulsars: a challenge to polar-cap models

abstract:
  Spectacular results of pulsar observations in X-ray and gamma-ray domains
gave a new boost to theoretical models of pulsar magnetospheric activity. A
challenging aspect of these efforts is that lightcurves and broadband energy
spectra of the brightest HE sources exhibit unexpected richness of features,
making each object almost a unique case to be interpreted with a custom-made
model. This review offers our subjective account of how the models of
high-energy radiation used within the framework of SCLF polar-cap scenarios
tackle these challenges. We describe major characteristics of all radiative
processes relevant for modeling the observed features. Then we address
successes as well as noticeable disadvantages of these models upon their
confrontation with the available data.


title: On the distance of Magellanic Clouds: first overtone Cepheids

abstract:
  We present a detailed comparison between predicted and empirical PL_{I,K}
relations and Wesenheit function for Galactic and Magellanic Clouds (MCs) First
Overtone (FO) Cepheids. We find that zero-points predicted by Galactic Cepheid
models based on a noncanonical (mild overshooting) Mass-Luminosity (ML)
relation are in very good agreement with empirical zero-points based on
HIPPARCOS parallaxes, while those based on canonical (no overshooting) ML
relation are about 0.2-0.3 mag brighter. We also find that predicted and
empirical PL_K relation and Wesenheit function give, according to optical (V,I
OGLE) and near-infrared (NIR, K, 2mass) data, mean distances to the MCs that
agree at the 2% level. Individual distances to the Large and the Small Cloud
are: 18.53+-0.08-19.04+-0.11 (theory) and 18.48+-0.13-19.01+-0.13 (empirical).
Moreover, predicted and empirical FO relations do not present, within the
errors, a metallicity dependence. Finaly, we find that the upper limit in the
FO period distribution is a robust observable to constrain the accuracy of
pulsation models. Current models agree within 0.1 in log P with the observed FO
upper limits.


title: Weak lensing study of galaxy biasing

abstract:
  We combine weak lensing measurements from the Red-Sequence Cluster Survey and
the VIRMOS-DESCART survey, and present the first direct measurements of the
bias parameter b and the galaxy-mass cross-correlation coefficient r on scales
ranging from 0.2 to 9.3 h_{50}^{-1} Mpc at a lens redshift z~0.35. We find
strong evidence that both b and r change with scale for our sample of lens
galaxies (19.5<R_C<21), which have luminosities around L_*. For the currently
favored cosmology (\Omega_m=0.3,\Omega_\Lambda=0.7), we find b=0.71^+0.06_-0.04
on a scale of 1-2 Mpc, increasing to ~1 on larger scales. The value of r has
only minimal dependence on the assumed cosmology. The variation of r with scale
is very similar to that of b, and reaches a minimum value of r=0.57^+0.08_-0.07
(at 1 Mpc). This suggests significant stochastic biasing and/or non-linear
biasing. On scales larger than ~4 Mpc the value of r is consistent with a value
of 1. In addition we use RCS data alone to measure the ratio b/r on scale
ranging from 0.15 to 12.5 Mpc, and find that the ratio varies somewhat with
scale. We obtain an average value of b/r=1.090+-0.035, in good agreement with
previous estimates. A (future) careful comparison of our results with models of
galaxy formation can provide unique constraints, as r is linked intimately to
the details of galaxy formation.


title:
Implications Regarding the Energetics Of the Collisional Formation of
  Kuiper Belt Satellites

abstract:
  Recently, it has been discovered that at least 1% of Kuiper Belt Objects
(KBOs) are accompanied by large satellites. Here we examine the energetics of
KBO satellite formation via collisions, finding collisions require a
dynamically excited Kuiper Belt. Further, even under optimistic assumptions
(including perfect accretion of the satellites), we find that collisional
processes cannot make KBO satellites at the observed frequency of occurrence
unless KBO projectiles large enough to generate the observed satellites were
\~40 times more numerous in the ancient past, resulting in an increased
collision rate with sufficiently large projectiles, or unless the fraction of
impact energy estimated to be imparted to ejecta is of order unity. Neither
alternative is very palatable. However, an easier to accept alternative also
exists: KBO primary and/or KBO satellite surface albedos presently be
underestimated by making the canonical assumption of 4% surface albedos;
specifically, surface albedos of KBO primaries and/or their satellites could be
in the neighborhood of 15% (or higher). This would reduce KBO primary and/or
satellite sizes and masses, thereby in turn reducing the required size of the
impacting projectiles required to generate KBO satellites, which in turn would
increase the impact rate with sufficiently large projectiles to values in line
with the observed fraction of KBOs with large satellites. This proposition is
expected to be easily testable with by SIRTF and by other means in the next 2
to 3 years.


title:
Imaging the disk around the luminous young star LkHalpha 101 with
  infrared interferometry

abstract:
  The Herbig Ae/Be star LkHalpha 101 has been imaged at high angular resolution
at a number of wavelengths in the near-infrared (from 1 to 3 microns) using the
Keck 1 Telescope, and also observed in the mid-infrared (11.15 microns) using
the U.C. Berkeley Infrared Spatial Interferometer (ISI). The resolved circular
disk with a central hole or cavity reported in Tuthill et al. (2001) is
confirmed. This is consistent with an almost face-on view (inclination < 35
deg) onto a luminous pre- or early-main sequence object surrounded by a massive
circumstellar disk. With a multiple-epoch study spanning almost four years,
relative motion of the binary companion has been detected, together with
evidence for changes in the brightness distribution of the central disk/star.
The resolution of the LkHalpha 101 disk by ISI mid-infrared interferometry
constitutes the first such measurement of a young stellar object in this
wavelength region. The angular size was found to increase only slowly from 1.6
to 11.15 microns, inconsistent with standard power-law temperature profiles
usually encountered in the literature, supporting instead models with a hot
inner cavity and relatively rapid transition to a cool or tenuous outer disk.
The radius of the dust-free inner cavity is consistent with a model of
sublimation of dust in equilibrium with the stellar radiation field.
Measurements from interferometry have been combined with published photometry
enabling an investigation of the energetics and fundamental properties of this
prototypical system.


title: The ionized gas in the Galactic Center Radio Arc

abstract:
  We present Infrared Space Observatory (ISO) observations of fine structure
lines toward the Radio Arc region, close to Sgr A, in the Galactic center
region (GCR). The ionization at large scale is dominated by the clusters of
massive stars in this region: the Quintuplet and the Arches cluster. Any other
possible mechanism as interaction with the magnetic fields revealed by the
Non-Thermal Filaments (NTFs) must play a minor role. The radiation in this area
is relatively hard ($T_\mathrm{eff}\sim 33-35$ kK) but diluted. It reaches
large distances due to the inhomogeneity of the medium.


title:
Enlarging the Parameter Space and our Understanding or The Radio
  Emission of Millisecond Pulsars

abstract:
  The understanding of pulsar radio emission demands a close look at all
regions of the huge parameter space present for pulsar observations. In this
review we concentrate on the space given by the range of observed pulse
periods, spanning four orders of magnitude. A comparative study of the emission
properties of millisecond pulsars and normal pulsars, both at radio and high
energy frequencies, promises to shed light on the still poorly understood
emission theory.


title: Warm molecular gas in the Galactic center region

abstract:
  We present some recent studies on the physical conditions and the chemistry
of the interstellar medium (ISM) in the Galactic center region (GCR). Large
scale shocks in the context of a bar potential can play a role in explaining
the observed properties, at least in some particular regions. Alternatively, we
propose that the observed properties (inhomogeneity, high temperatures of the
molecular gas, rich chemistry,...) of the GCR ISM can be the consequence of the
recent past ($10^6-10^7$ years ago) of massive star formation in the GCR.


title:
Photometric amplitudes and phases of nonradial oscillation in rotating
  stars

abstract:
  Effects of rotational mode coupling on photometric parameters of stellar
oscillations are studied. At moderate rotation rates, a strong coupling between
modes of spherical harmonic degree, $\ell$, differing by 2 and of the same
azimuthal order, $m$, takes place if the frequencies are close. This is a
common situation amongst main sequence pulsators. Numerical results for a
sequence of $\beta$ Cephei star models are reported for the two- and three-mode
couplings.
  One consequence of mode coupling is that modes of higher degree should be
considered in photometric mode identification. Modes with nominal degree
$\ell>2$ acquire substantial $\ell\le2$ components and therefore are more
likely to reach detectable amplitudes. Coupled mode positions in the amplitude
ratio - phase difference diagrams, based on multicolour photometry, become both
aspect- and $m$-dependent. Examples of the mode path in the diagram with
varying aspect are given. The diagrams remain a useful tool for mode
identification in rotating stars but the tool must be used with care.


title: Coordinated Multiwavelength Observations of V410Tau

abstract:
  In November 2001 we undertook a coordinated observing campaign to study the
connection between X-ray and optical variability in the weak-line T Tauri star
V410Tau. The observing plan included three 15 ksec observations with Chandra
using the Advanced CCD Imaging Spectrometer for Spectroscopy scheduled for
different phases of the known 1.87 d starspot cycle. Photometric and
spectroscopic monitoring of V410Tau involving telescopes on three different
continents was scheduled simultaneously with the Chandra exposures.


title:
Study of Proto Strange Stars (PSS) in Temperature and Density Dependent
  Quark Mass Model

abstract:
  We report on the study of the mass-radius (M-R) relation and the radial
oscillations of proto strange stars. For the quark matter we have employed the
well known density dependent quark mass model and its very recent modification,
the temperature and density dependent quark mass model. We find that the
maximum mass the star can support increases significantly with the temperature
of the star in this model which implies that transition to a black hole at the
early stage of formation of the star is inhibited. As for the neutrinos, we
find, contrary to the expectation that the M-R and oscillation frequencies are
almost independent of the neutrino chemical potentials.


title: XMM-Newton detection of Nova Muscae 1991 in Quiescence

abstract:
  The soft X-ray transient GU Mus has been detected by XMM-Newton in the
quiescent state. The source is very faint, with a 0.5-10.0 keV unabsorbed flux
of $\simeq 1.1 \times 10^{-14}$ ergs cm$^{-2}$ s$^{-1}$. The spectra is well
fit by an absorbed powerlaw with a photon index of $ \alpha = 1.6 \pm 0.4$,
close to the value seen when the source was in the low/hard state in Aug. 1991.
  From our observed luminosity, it seems unlikely that the quiescent state
emission is dominated by coronal X-rays from the secondary. The flux also
appears to be in agreement with the ADAF model of BH-transients in quiescence.


title:
Generalised mass variation formula for a stationary axisymmetric star or
  black hole with surrounding accretion disc

abstract:
  The general relativistic mass-energy variation formula for axisymmetric
equilibrium states of a selfgravitating system is developed in the particular
case for which the relevant matter consists of a perfectly conducting
multiconstituent fluid (or superfluid) with stationary circular or convective
motion.


title:
Newtonian motion as origin of anisotropy of the local velocity field of
  galaxies

abstract:
  The origins of recently reported anisotropy of the local velocity field of
nearby galaxies (velocities < 500 km/s corresponding to the distance less than
8 Mpc) are studied. The exact solution of the Newtonian equation for the
expanding Universe is obtained. This solution allows us to separate the
Newtonian motion of nearby galaxies from the Hubble flow by the transition to
the conformal coordinates. The relation between the Hubble flow and the
Newtonian motion is established. We show that the anisotropic local velocity
field of nearby galaxies can be formed by such a Newtonian motion in the
expanding Universe, if at the moment of the capture of galaxies by the central
gravitational field.


title:
Detection of delta Scuti-like pulsation in H254, a pre-main sequence
  F-type star in IC 348

abstract:
  We present time series observations of intermediate mass PMS stars belonging
to the young star cluster IC 348. The new data reveal that a young member of
the cluster, H254, undergoes periodic light variations with delta Scuti-like
characteristics. This occurrence provides an unambiguous evidence confirming
the prediction that intermediate-mass pre-main sequence (PMS) stars should
experience this transient instability during their approach to the
main-sequence. On the basis of the measured frequency f=7.406 c/d, we are able
to constrain the intrinsic stellar parameters of H254 by means of linear, non
adiabatic, radial pulsation models. The range of the resulting luminosity and
effective temperature permitted by the models is narrower than the
observational values. In particular, the pulsation analysis allows to derive an
independent estimate of the distance to IC 348 of about 320 pc. Further
observations could either confirm the monoperiodic nature of H254 or reveal the
presence of other frequencies.


title: X-ray spectral diagnostics of the immediate environment of GRB 991216

abstract:
  The recent report of iron line features in the afterglow of the gamma-ray
burst (GRB) 991216 has important implications for the properties of the
radiating material and hence the nature of the immediate burst environment. We
argue that the putative strong Fe emission line can be attributed to the
reflected emission from Thomson-thick matter which is illuminated by a
power-law continuum. The ionization parameter of the material (i.e., the flux
to density ratio) is around 10^3, resulting in a Fe K line from He-like iron. A
supersolar abundance of iron is not required by the data. Interestingly, the
ionizing continuum must be harder than the observed one. We interpret this as
due to the fact that the observed continuum is dominated by the standard blast
wave emission, while the line is produced by reprocessing material located at
much smaller radii.


title: The Brightest Black Holes

abstract:
  I suggest that there are two classes of ultraluminous X-ray sources (ULXs),
corresponding to super-Eddington mass inflow in two situations: (a)
thermal-timescale mass transfer in high-mass X-ray binaries, and (b)
long-lasting transient outbursts in low-mass X-ray binaries. These two classes
are exemplified by SS433 and microquasars like GRS 1915+105 respectively. The
observed ULX population is a varying mixture of the two, depending on the star
formation history of the host galaxy. ULXs in galaxies with vigorous star
formation (such as the Antennae) are generally SS433--like, while ULXs in
elliptical galaxies must be of the microquasar type. The latter probably have
significantly anisotropic radiation patterns. They should also be variable, but
demonstrating this may require observations over decades. The close analogy
between models of X-ray binaries and active galactic nuclei (AGN) suggests that
there should exist an apparently super-Eddington class of the latter, which may
be the ultrasoft AGN, and a set of X-ray binaries with Doppler--boosted X-ray
emission. These are presumably a subset of the ULXs, but remain as yet
unidentified.


title:
Giant low surface brightness halos in distant radio galaxies:
  USS0828+193

abstract:
  We present results on the spectroscopic study of the ionized gas in the high
redshift radio galaxy USS0828+193 at z=2.57. Thanks to the high S/N of the
emission lines in the Keck spectrum, we have been able to perform a detailed
kinematic study by means of the spectral decomposition of the emission line
profiles. This study reveals the existence of two types of material in this
object: a) a low surface brightness component with apparent quiescent
kinematics consistent with gravitational motions and b) a perturbed component
with rather extreme kinematics. The quiescent halo extends across the entire
object for ~80 kpc. It is enriched with heavy elements and apparently ionized
by the continuum from the active nucleus.
  The properties of the quiescent halo and its origin are discussed in this
paper. We propose that it could be part of a structure that surrounds the
entire object, although its nature is not clear (a rotating disc? low surface
brightness satellites? a cooling flow nebula? material ejected in galactic
winds? other?).


title: Comparative Chemistry of Diffuse Clouds IV: CH

abstract:
  We observed the 3335 MHz (9cm) F=1-1 line of CH toward a sample of diffuse
clouds occulting compact extragalactic mm-wave continuum sources, using the old
NRAO 43m telescope. Because radiofrequency observations of CH really must be
calibrated with reference to a known CH abundance, we begin by deriving the
relationships between CH, EB-V, H2 and other hydrides found by optical
spectroscopy. No simple relationship exists between N(CH) and EB-V, since N(CH)
is strongly bimodal with respect to reddening for EB-V < 0.3 mag and the
typical range in the N(CH)/EB-V ratio is an order of magnitude or more at any
given EB-V > 0.3 mag. However, N(CH)/N(H2) = 4.3 +/- 1.9 x 10^-8 in the mean
and N(CH) varies as N(H2)^(1.00+/-0.06) for 10^{19} < N(H2) < 10^{21} cm^-2. If
CH is a good predictor of H2, 40-45% of the hydrogen in the local
diffuse/translucent ISM is in the molecular form at the accepted mean density,
higher than previous estimates found in samples of lower-than-average mean
density. Optical observations of the population ratios in the upper and lower
halves of the CH lambda-doublet suggest that the brightness of the 3335 MHz CH
line should be double-valued at a given CH column density in diffuse gas:
double-valuedness is noticeable in our data when comparing CH with CO or HCO+.
The CH brightness at 3335 MHz is mildly bimodal with respect to CO emission in
our diffuse cloud data but much more strongly bimodal when comparing diffuse or
translucent gas and dark gas. The CH Lambda-doublet is generally inverted in
diffuse gas but we did not succeed in measuring the excitation temperature
except toward 3C123 where we confirm one older value Tex ~ -10 K.


title:
Gravitating mass profiles of nearby galaxy clusters and relations with
  X-ray gas temperature, luminosity and mass

abstract:
  We consider a sample of 22 nearby clusters of galaxies observed with the
Medium Energy Concentrator Spectrometer (MECS) on board of BeppoSAX. They cover
the range in gas temperature between 3 and 10 keV, with bolometric X-ray
luminosity between 2e44 erg/s and 6e45 erg/s. Using the de-projected gas
temperature and density profiles resolved in a number of bins between 5 and 7
and obtained from this dataset only, we recover the total gravitating mass
profiles for 20 objects just applying the (i) spherical symmetry and (ii)
hydrostatic equilibrium assumptions. We investigate the correlations between
total mass, gas temperature, luminosity at several overdensities values and
find that the slopes of these relations are independent from the considered
overdensity and consistent with what is predicted from the cluster scaling
laws. The best-fit results on the normalization of the M-T relation are
slightly lower, but still consistent considering the large errors that we
measure, with hydrodynamical simulations. A segregation between relaxed and
non-relaxed systems is present in each plane of these relations pointing out to
a significant component in their intrinsic scatter. This segregation becomes
more evident at higher overdensities and when physical quantities, like M_gas
and L, that are direct function of the amount of gas observed, are considered.


title:
Tracing the Warm-Hot Intergalactic Medium at Low Redshift: X-ray Forest
  Observations Towards H1821+643

abstract:
  We present a high resolution (R~500) X-ray spectrum of the bright quasar
H1821+643 (z=0.297), obtained in a 470 ksec Chandra observation. We search for
X-ray absorption by highly ionized metal species, OVII and OVIII in particular,
at the redshifts of the six intervening OVI absorption systems known from UV
studies. We detect features with >~2-sigma significance at the predicted OVII
and OVIII wavelengths of one OVI system, at the OVII wavelength of a second,
and at the NeIX wavelength of a third. We find two additional features of
comparable strength (one OVII and one OVIII) within 1000 km/s of OVI redshifts.
The 1-sigma constraints in the two detected OVI systems imply gas overdensities
lower than the values delta>100 expected in virialized systems, suggesting that
the absorption arises in lower density, filamentary structures. At the 2-sigma
level, however, the physical constraints are weak. If we treat our 2-sigma
detections of known OVI systems as real, but assume minimal OVII and OVIII in
the other systems, we estimate [f(OVI)+f(OVII)+f(OVIII)]/f(OVI) = 32 +/- 9 for
the average ratio of all highly ionized oxygen species to OVI. Combined with
estimates of the total column density of OVI absorption per unit redshift, this
ratio implies a total baryon fraction associated with detected OVI absorbers
Omega_b(OVI)~0.03/h_70, a substantial fraction of the baryon density predicted
by BBN, and larger than that in known low redshift components. Because of the
limited S/N of the detections, these results must be treated with caution.
Nonetheless, the combination of the OVI data with these X-ray forest
measurements provides the most direct evidence to date for the pervasive,
moderate density, shock-heated intergalactic medium predicted by leading
cosmological scenarios. (Abridged.)


title: Galaxies with a Central Minimum in Stellar Luminosity Density

abstract:
  We used HST WFPC2 images to identify six early-type galaxies with surface-
brightness profiles that decrease inward over a limited range of radii near
their centers. The implied luminosity density profiles of these galaxies have
local minima interior to their core break radii. NGC 3706 harbors a high
surface brightness ring of starlight with radius ~20 pc. Its central structure
may be related to that in the double-nucleus galaxies M31 and NGC 4486B. NGC
4406 and NGC 6876 have nearly flat cores that on close inspection are centrally
depressed. Colors for both galaxies imply that this is not due to dust
absorption. The surface brightness distributions of both galaxies are
consistent with stellar tori that are more diffuse than the sharply defined
system in NGC 3706. The remaining three galaxies are the brightest cluster
galaxies in A260, A347, and A3574. Color information is not available for these
objects, but they strongly resemble NGC 4406 and NGC 6876 in their cores. The
thin ring in NGC 3706 may have formed dissipatively. The five other galaxies
resemble the endpoints of some simulations of the merging of two gas-free
stellar systems, each harboring a massive nuclear black hole. In one version of
this scenario, diffuse stellar tori are produced when stars initially bound to
one black hole are tidally stripped away by the second black hole.
Alternatively, some inward-decreasing surface-brightness profiles may reflect
the ejection of stars from a core during the hardening of the binary black hole
created during the merger.


title: Chandra observations of the nearby spiral galaxy NGC6503

abstract:
  We have observed the nearby spiral galaxy NGC6503 using Chandra. Seven
discrete sources associated with the galaxy have been found, one of them
coincident with its Liner-starburst nucleus. One of the sources corresponds to
a ULX with Lx >~ 10e39 ergs/s. Previous ROSAT observations of the galaxy show
that this source has varied by at least a factor 3 in the last 6 years. No
evidence is found for strong diffuse emission in the nuclear region or the
presence of a low luminosity AGN.


title:
Mini-LANNDD: A Very Sensitive Neutrino Detector To Measure sin sup 2(2
  theta sub 13)

abstract:
  The ICARUS Detector at the LGNS will carry out a sensitive search for a sin
sup 2(2 theta sub 13). We describe a small version for the LANNDD proton decay
detector (70kT Liquid Argon) to measure nu sub mu -> nu sub e in a low energy
or off-axis neutrino beam. We find an optimal detector size is 5 kT and at a
distance of about 700 km from a high-energy neutrino source. This detector uses
the ICARUS method.


title:
The Failure of Self-Interacting Dark Matter to solve the Overabundance
  of Dark Satellites and the Soft Core Question

abstract:
  Self-interacting dark matter was proposed by Spergel & Steinhardt (2000) to
alleviate two conflicts between Cold Dark Matter (CDM) models and observations.
Firstly, CDM N-body simulations predict dark matter halo density profiles that
diverge at the centre in disagreement with the constant density cores observed
in late-type dwarf and Low Surface Brightness (LSB) galaxies. Secondly, N-body
simulations predict an overabundance of subhalos in the Galactic halo. Using a
simple semi-analytical argument we show that weakly self-interacting dark
matter models, which can produce halo cores of the sizes observed in dark
matter dominated galaxies, are unable to reconcile the number of satellites in
the Galactic halo with the observed number of dwarf galaxies in the Local
Group.


title: Properties of Dark Matter Haloes

abstract:
  An overview is presented of the main properties of dark matter haloes, as we
know them from observations, essentially from rotation curves around spiral and
dwarf galaxies. Detailed rotation curves are now known for more than a thousand
galaxies, revealing that they are not so flat in the outer parts, but rising
for late-types, and falling for early-types. A well established result now is
that most bright galaxies are not dominated by dark matter inside their optical
disks. Only for dwarfs and LSB (Low Surface Brightness galaxies) dark matter
plays a dominant role in the visible regions. The 3D-shape of haloes are
investigated through several methods, that will be discussed: polar rings,
flaring of HI planes, X-ray isophotes.
  It is not yet possible with rotation curves to know how far haloes extend,
but tentatives have been made. It will be shown that the dark matter appears to
be coupled to the gas in spirals and dwarfs, suggesting that dark baryons could
play the major role in rotation curves. Theories proposing to replace the
non-baryonic dark matter by a different dynamical or gravity law, such as MOND,
have to take into account the dark baryons, especially since their spatial
distribution is likely to be quite different from the visible matter.


title: Identifying X-ray Sources in Bulge and Disk Galaxies from X-ray Colors

abstract:
  The X-ray populations of Local group galaxies have been classified in detail
by Einstein, ROSAT and ASCA revealing a mix of binaries, supernova remnants and
HII regions. However, these observatories were unable to resolve X-ray sources
in galaxies beyond the local group. With Chandra's exquisite spatial resolution
we are able to resolve sources in a sample of nearby galaxies. We show that
there are highly significant differences in the X-ray colors of sources in
bulge and disk systems. These differences can be used as a basis to classify
sources as low and high mass X-ray binaries, supernova remnants and supersoft
sources. While it is impossible to identify any individual source on the basis
of X-ray color alone, the observations presented here suggest that it is
possible to separate sources into groups dominated by a single type of source.
This classification scheme is likely to be very useful in population studies,
where it is crucial to distinguish between different classes of objects.


title: Convective Core Mixing: a Metallicity Dependence?

abstract:
  The main scope of this paper is to investigate the possible existence of a
metallicity dependence of the overshooting from main sequence stars turbulent
cores. We focus on objects with masses in the range ~2.5 Msol - ~25 Msol.
Basically, evolutionary time scale ratios are compared with star numbers ratios
on the main sequence. Star populations are synthesized using grids of
evolutionary tracks computed with various overshooting amounts. Observational
material is provided by the large and homogeneous photometric database of OGLE
2 project for the Magellanic clouds. Attention is paid to the study of
uncertainties: distance modulus, intergalactic and interstellar reddening, IMF
slope and average binarity rate. Rotation and chemical composition gradient are
also considered. The result for the overshooting distance is l_over(SMC)= 0.40
+0.12-0.06 Hp (Z=0.004) and l_over(LMC)= 0.10+0.17-0.10 Hp (Z=0.008) suggesting
a possible dependence of the extent of the mixed central regions with
metallicity within the considered mass range. Unfortunately it is not yet
possible to fully disentangle effects of mass and chemical composition.


title: Evidence for a Collisional Mechanism Affecting Kuiper Belt Object Colors

abstract:
  The Kuiper Belt (KB) region of the solar system, stretching from 30 to at
least 50 AU, contains Pluto-Charon, some ~105 Kuiper Belt Objects (KBOs) larger
than 100 km in diameter, and myriad smaller bodies produced by collisions among
KBOs (Farinella, Davis, & Stern 2000). The most notable physical attribute of
the KBOs discovered to date is their reflectance color diversity, ranging from
gray (i.e., neutral) to very red (Tegler & Romanishin 2000). We report here
evidence for a statistical correlation between the colors of KBOs and the mean
random impact speed that these objects experience, lending evidence to
suggestions some years ago by modelers (Jewitt & Luu 1996) that a competition
between collisional resurfacing and radiation reddening may contribute to the
color diversity of KBOs.