title:
Studies of the Relativistic Binary Pulsar PSR B1534+12. II. Origin and
  Evolution

abstract:
  We have recently measured the angle between the spin and orbital angular
momenta of PSR B1534+12 to be either 25+/-4 deg or 155+/-4 deg. This
misalignment was almost certainly caused by an asymmetry in the supernova
explosion that formed its companion neutron star. Here we combine the
misalignment measurement with measurements of the pulsar and companion masses,
the orbital elements, proper motion, and interstellar scintillation. We show
that the orbit of the binary in the Galaxy is inconsistent with a velocity kick
large enough to produce a nearly antialigned spin axis, so the true
misalignment must be ~25 deg. Similar arguments lead to bounds on the mass of
the companion star immediately before its supernova: 3+/-1 Msun. The result is
a coherent scenario for the formation of the observed binary. After the first
supernova explosion, the neutron star that would eventually become the observed
pulsar was in a Be/X-ray type binary system with a companion of at least 10--12
Msun. During hydrogen (or possibly helium) shell burning, mass transfer
occurred in a common envelope phase, leaving the neutron star in a roughly
half-day orbit with a helium star with mass above ~3.3 Msun. A second phase of
mass transfer was then initiated by Roche lobe overflow during shell helium
burning, further reducing both the helium star mass and orbital period before
the second supernova. Scenarios that avoid Roche lobe overflow by the helium
star require larger helium star masses and predict space velocities
inconsistent with our measurements. The companion neutron star experienced a
velocity kick of 230+/-60 km/s at birth, leading to a systemic kick to the
binary of 180+/-60 km/s.


title: Spin Rates and Magnetic Fields of Millisecond Pulsars

abstract:
  Observations made using the Rossi X-ray Timing Explorer have shown that
accreting weak-field neutron stars in low-mass X-ray binary systems (LMXBs)
produce three distinct types of millisecond X-ray oscillations that can be used
to determine the spin rates and estimate the magnetic fields of these stars.
These oscillations show that more than two dozen neutron stars in LMXBs have
spin rates and magnetic fields in the range that will make them radio-emitting
millisecond pulsars when accretion ceases, supporting the hypothesis that
neutron stars in LMXBs are the progenitors of the rotation-powered millisecond
pulsars. The spins of the 16 known accreting millisecond pulsars in LMXBs are
consistent with spin-up to accretion spin equilibrium for magnetic fields
ranging from 3 x 10^7 G to 3 x 10^8 G and time-averaged accretion rates ranging
from 3 x 10^{-3} MdotE to MdotE, provided these stars have been accreting long
enough. The P-Pdot distribution of rotation-powered millisecond pulsars
indicates that their initial spins are set by spin-up to spin equilibrium at
accretion rates ranging from 10^{-3} MdotE to MdotE or that they never reached
accretion spin equilibrium.


title:
Pulsar Wind Nebulae and the X-Ray Emission of Non-Accreting Neutron
  Stars

abstract:
  The general properties of the non-thermal non-pulsed X-ray emission of
rotation powered pulsars are investigated in the context of a pulsar wind
nebula model. An examination of the observed X-ray emission from a sample of 23
pulsars from ASCA in the energy range between 2-10 keV reveals that the
relation of X-ray luminosity, $L_x$, to the pulsar spin down power, $\dot{E}$,
is steeper for the non-pulsed component than for the pulsed component.
Specifically, $L_{x}^{npul} \propto \dot{E}^{1.4 \pm 0.1}$ for the non-pulsed
component, whereas $L_{x}^{pul} \propto \dot{E}^{1.2 \pm 0.08}$ for the pulsed
component. The former relation is consistent with emission from a pulsar wind
nebula model in which $L_{x}^{npul} \propto \dot{E}^{p/2}$ where $p$ is the
power law index of the electron energy distribution. The relation for the
pulsed component, on the other hand, is consistent with a magnetospheric
emission model.


title: Noise storm continua: power estimates for electron acceleration

abstract:
  We use a generic stochastic acceleration formalism to examine the power
$L_{\rm in}$ (${\rm erg s^{-1}}$) input to nonthermal electrons that cause
noise storm continuum emission. The analytical approach includes the derivation
of the Green's function for a general second-order Fermi process, and its
application to obtain the particular solution for the nonthermal electron
distribution resulting from the acceleration of a Maxwellian source in the
corona. We compare $L_{\rm in}$ with the power $L_{\rm out}$ observed in noise
storm radiation. Using typical values for the various parameters, we find that
$L_{\rm in} \sim 10^{23-26}$ ${\rm erg s^{-1}}$, yielding an efficiency
estimate $\eta \equiv L_{\rm out}/L_{\rm in}$ in the range $10^{-10} \lsim \eta
\lsim 10^{-6}$ for this nonthermal acceleration/radiation process. These
results reflect the efficiency of the overall process, starting from electron
acceleration and culminating in the observed noise storm emission.


title: A Homogenous Set of Globular Cluster Relative Distances and Reddenings

abstract:
  We present distance modulus and reddening determinations for 72 Galactic
globular clusters from the homogeneous photometric database of Piotto et al.
(2002), calibrated to the HST flight F439W and F555W bands. The distances have
been determined by comparison with theoretical absolute magnitudes of the ZAHB.
For low and intermediate metallicity clusters, we have estimated the apparent
Zero Age Horizontal Branch (ZAHB) magnitude from the RR Lyrae level. For metal
rich clusters, the ZAHB magnitude was obtained from the fainter envelope of the
red HB. Reddenings have been estimated by comparison of the HST
colour-magnitude diagrams (CMD) with ground CMDs of low reddening template
clusters. The homogeneity of both the photometric data and the adopted
methodological approach allowed us to obtain highly accurate relative cluster
distances and reddenings. Our results are also compared with recent
compilations in the literature.


title: Clusters and Superclusters in the Sloan Survey

abstract:
  We find clusters and superclusters of galaxies using the Data Release 1 of
the Sloan Digital Sky Survey. Density fields with smoothing lengthst of 10 and
0.8 Mpc/h are calculated. We found that galaxies and clusters in a high-density
environment have luminosities that are five to ten times higher than in a
low-density environment. Numerical simulations show that in underdense regions
most particles form a rarefied population of pregalactic matter whereas in
overdense regions most particles form a clustered population in rich clusters.
Simulations show also that very massive superclusters are great attractors and
have small bulk motions.


title: Is the radion a chameleon?

abstract:
  The chameleon mechanism is a way to give an effective mass to a light scalar
field via field self-interaction and interaction with matter. We study this
mechanism in models in which the couplings are field dependent and find that
the properties are very different from the case of constant couplings. The
consequence of a runaway potential for the radion field in brane world
scenarios and whether the radion can play the role of dark energy is
investigated. The cosmological evolution during the inflationary epoch, the
radiation and the matter dominated epochs are discussed as is the compatibility
of the radion field with local tests of gravity.


title:
H-alpha kinematics of a z ~ 1 disc galaxy from near-IR integral field
  spectroscopy

abstract:
  In this letter we present the first 3D spectroscopic study of H-alpha
emission in a z ~ 1 field galaxy with an integral field unit. Using the CIRPASS
spectrograph on Gemini-South we map the spatial and velocity distribution of
H-alpha emission in the z=0.819 galaxy CFRS 22.1313. We detect two H-alpha
emitting regions with a velocity separation of 220+/-10 km/s. Combining the 2D
map of H-alpha emission with HST F814W imaging, we determine a lower limit of
180+/-20 km/s for the rotation velocity of this M_B(rest) ~ -21 galaxy. We note
that our value is significantly higher than the rotation velocity of
120+/-10km/s reported by Barden et al. (2003) for their long-slit spectroscopic
study of this galaxy. Our lower limit on the rotation velocity is entirely
consistent with no evolution of the rest B-band Tully-Fisher relation. The
position of this galaxy relative to the mean rest B-band Tully-Fisher relation
of Tully & Pierce (2000) is consistent with brightening of no more than ~ 1mag
at z=0.8. A larger integral field unit sample, without the uncertainties
inherent to long-slit samples, is needed to accurately determine the evolution
of the Tully-Fisher relation out to z ~ 1.


title: The SCUBA Local Universe Galaxy Survey Optically-Selected Sample

abstract:
  We discuss the progress of the SCUBA Local Universe Galaxy Survey (SLUGS),
the first large, statistical sub-mm survey of the local universe. Since our
original survey of a sample of 104 IRAS-selected galaxies we have recently
completed a sample of 78 Optically-Selected galaxies. Since SCUBA is sensitive
to the large proportion of dust too cold to be detected by IRAS the addition of
this optically-selected sample allows us for the first time to determine the
amount of cold dust in galaxies of different Hubble types. We detect 6
ellipticals in the sample and find them to have dust masses in excess of 10^7
solar masses. We derive local sub-mm luminosity functions, both directly for
the two samples, and by extrapolation from the IRAS PSCz, and find excellent
agreement.


title: Type-I superconductivity and neutron star precession

abstract:
  Type-I proton superconducting cores of neutron stars break up in a magnetic
field into alternating domains of superconducting and normal fluids. We examine
two channels of superfluid-normal fluid friction where (i) rotational vortices
are decoupled from the non-superconducting domains and the interaction is due
to the strong force between protons and neutrons; (ii) the non-superconducting
domains are dynamically coupled to the vortices and the vortex motion generates
transverse electric fields within them, causing electronic current flow and
Ohmic dissipation. The obtained dissipation coefficients are consistent with
the Eulerian precession.


title: The clustering of Luminous Red Galaxies around MgII absorbers

abstract:
  We study the cross-correlation between 212 MgII quasar absorption systems and
\~20,000 Luminous Red Galaxies (LRGs) selected from the Sloan Digital Sky
Survey Data Release 1 in the redshift range 0.4<z<0.8. The MgII systems were
selected to have 2796 & 2803 rest-frame equivalent widths >=1.0 Angstrom and
identifications confirmed by the FeII 2600 or MgI 2852 lines. Over comoving
scales 0.05--13 h^-1 Mpc, the MgII--LRG cross-correlation has an amplitude
0.69+/-0.09 times that of the LRG--LRG auto-correlation. Since LRGs have
halo-masses greater than 3.5 x 10^12 solar masses for M_R<-21, this relative
amplitude implies that the absorber host-galaxies have halo-masses greater than
2--8 x 10^11 Msun. For 10^13 Msun LRGs, the absorber host-galaxies have
halo-masses 0.5--2.5 x 10^12 Msun. Our results appear consistent with those of
Steidel et al. (1994) who found that MgII absorbers with W_r>=0.3 Angstrom are
associated with ~0.7 L^*_B galaxies.


title:
Circumnuclear Structure and Black Hole Fueling: HST/NICMOS Imaging of
  250 Active and Normal Galaxies

abstract:
  Why are the nuclei of some galaxies more active than others? If most galaxies
harbor a central massive black hole, the main difference is probably in how
well it is fueled by its surroundings. We investigate the hypothesis that such
a difference can be seen in the detailed circumnuclear morphologies of galaxies
using several quantitatively defined features, including bars, isophotal
twists, boxy and disky isophotes, and strong non-axisymmetric features in
unsharp masked images. These diagnostics are applied to 250 high-resolution
images of galaxy centers obtained in the near-infrared with NICMOS on HST. To
guard against the influence of possible biases and selection effects, we have
carefully matched samples of Seyfert 1, Seyfert 2, LINER, starburst and normal
galaxies in their basic properties, taking particular care to ensure that each
was observed with a similar average scale (10-15 parsecs per pixel). Several
morphological differences among our five different spectroscopic
classifications emerge from the analysis. The HII/starburst galaxies show the
strongest deviations from smooth elliptical isophotes, while the normal
galaxies and LINERS have the least disturbed morphology. The Seyfert 2 galaxies
have significantly more twisted isophotes than any other category, and the
early-type Seyfert 2s are significantly more disturbed than the early-type
Seyfert 1s. The morphological differences between Seyfert 1s and 2s suggest
that more is at work than simply the viewing angle of the central engine. They
may correspond to different evolutionary stages.


title: Detectability of Extrasolar Planets in Radial Velocity Surveys

abstract:
  Radial velocity surveys are beginning to reach the time baselines required to
detect Jupiter analogs, as well as sub-Saturn mass planets in close orbits.
Therefore it is important to understand the sensitivity of these surveys at
long periods and low amplitudes. In this paper, I derive analytic expressions
for the detectability of planets at both short and long periods, for circular
and eccentric orbits. I suggest an extension of the Lomb-Scargle periodogram
for Keplerian orbits, and describe how to estimate the false alarm probability
associated with a Keplerian fit. Using this to investigate the detectability of
eccentric orbits shows that there are significant selection effects against
eccentric orbits for e>0.6, and the small number of highly eccentric planets
discovered so far may reflect this. Finally, I present a Bayesian approach to
the periodogram, which emphasises the equivalence of least squares and
periodogram techniques.


title:
The HARPS survey for southern extra-solar planets II. A 14 Earth-masses
  exoplanet around mu Arae

abstract:
  In this letter we present the discovery of a very light planetary companion
to the star mu Ara (HD160691). The planet orbits its host once every 9.5days,
and induces a sinusoidal radial velocity signal with a semi-amplitude of 4.1
m/s, the smallest Doppler amplitude detected so far. These values imply a mass
of m2 sini = 14 earth-masses. This detection represents the discovery of a
planet with a mass slightly smaller than that of Uranus, the smallest ``ice
giant" in our Solar System. Whether this planet can be considered an ice giant
or a super-earth planet is discussed in the context of the core-accretion and
migration models.


title: Flare-induced fountains and buried flares in AGN

abstract:
  We discuss the local physical changes at the surface of an AGN accretion disk
after the onset of a magnetic flare. The X-ray irradiation by a flare creates a
hot spot at the disk surface where the plasma both heats up and expands in the
vertical direction in order to regain the hydrostatic equilibrium. Assuming
that the magnetic loop causing the flare is anchored deeply within the disk
interior, we derive analytical estimates for the vertical dimension H_hot and
the optical depth tau_es of the heated atmosphere as a function of the position
within the spot. We perform computations for various values of the accretion
rate dm/dt, the fraction f_cor of radiation dissipated within the disk corona,
and the covering factor f_cover of the disk surface with flare-illuminated
patches. It turns out that generally we can distinguish three characteristic
radial zones within the disk showing a qualitatively different behavior of the
heated material. In the innermost regions of the disk (inner zone) the
expansion of the disk material is restricted by strong gravitational forces.
Further out, the flare source, initially above the disk, soon becomes embedded
by the expanding disk atmosphere. At these intermediate disk radii (middle
zone) the material is optically thick thus greatly modifying the observed
radiation by multiple Compton scattering. We show exemplary spectra models
obtained from Monte Carlo simulations illustrating the trends. In the outermost
regions of the disk (outer zone) the expanding material is optically thin and
its influence on the observed spectra is smaller but pressure gradients in
radial directions should cause the development of a fountain-like dynamical
structure around the flare source. We discuss the observational consequences of
our results.


title: Seti with Ska

abstract:
  SETI with SKA would be by far the most powerful SETI search ever undertaken,
covering enough stars with enough sensitivity to probe significantly further
towards those other Earth civilisations than previous ones. This paper
discusses the rationale behind radio SETI searches, and explains why SKA will
be such as big step forward and will make few demands on telescope time.


title: Extra-solar planets with SKA

abstract:
  SKA would have distinct capabilities for studies associated with extra-solar
planets, their formation and properties.


title:
Semi-analytical model of galaxy formation with high-resolution N-body
  simulations

abstract:
  We model the galaxy formation in a series of high-resolution N-body
simulations using the semi-analytical approach. Unlike many earlier
investigations based on semi-analytical models, we make use of the subhalos
resolved in the $N$-body simulations to follow the mergers of galaxies in dark
halos, and we show that this is pivotal in modeling correctly the galaxy
luminosity function at the bright end and the bimodal nature of galaxy color
distribution. Mergers of galaxies based on subhalos also result in many more
bright red galaxies at high $z$. The semi-analytical model we adopt is similar
to those used in earlier semi-analytical studies, except that we consider the
effect of a prolonged cooling in small halos and that we explicitly follow the
chemical enrichment in the interstellar medium. We use our model to make
predictions for the properties of the galaxy population at low redshift and
compare them with various current observations. We find that our model
predictions can match the luminosity functions of galaxies in various wavebands
redder than the u-band. The shape of the luminosity function at bright end is
well reproduced if galaxy mergers are modeled with the merger trees of subhalos
and the steep faint-end slope can be moderated if the gas cooling time in
low-mass halos is comparable to the age of the universe. The model with
subhalos resolved can reproduce the main features in the observed color bimodal
distribution, though it still predicts too many bright blue galaxies. The same
model can also match the color-magnitude relation for elliptical galaxies in
clusters, the metallicity-luminosity relation.


title:
Polarization properties of broad absorption line QSOs : new statistical
  clues

abstract:
  We report the results of statistical tests performed on a sample of 139 broad
absorption line (BAL) QSOs with good quality optical spectra and/or optical
polarization data. Correlations between optical indices and the polarization
degree p_0 are systematically searched for. In order to identify the most
important correlations, we perform a principal component analysis with a sample
of 30 BAL QSOs and eight quantities (including p_0). Most of the variance in
the data is contained in two principal components (PC): PC1 is mainly dominated
by the correlation between the balnicity index BI and the strength of the feii
emission, and may be driven by the accretion rate of matter onto the central
compact object. The variance in PC2 is essentially due to the anti-correlation
between p_0 and the detachment index DI. PC2 may be related to the orientation
of the BAL QSOs with respect to the line of sight. We also consider a
spectropolarimetric sample of 21 BAL QSOs for which we define four indices
describing the polarization properties of the absorption and emission lines. We
find a possible anti-correlation between the detachment index and a quantity SI
which measures the ratio of the depths of the civ absorption in the polarized
flux and in the total flux. This correlation indicates that in BAL QSOs with P
cygni profiles, the BAL troughs in the polarized flux are nearly as deep as in
the total flux while, in BAL QSOs with detached absorptions, the BAL troughs in
the polarized flux are much weaker than in the total flux. We show that our
main results may be explained in the framework of a 'two-component' wind model.
In this model, the broad absorption occurs in a dense equatorial wind emerging
from the accretion disk, while scattering and polarization mainly take place in
a polar region.


title:
The Strong Magnetic Field Decay and Evolution of Radio Pulsars on the
  P--\.{P} Diagram

abstract:
  In this work we have analysed various data on radio pulsars and we have shown
that magnetic field decay of a factor about 10-20 is necessary to explain their
evolution, in particular to remove the discrepancy between the characteristic
and the real ages. The character of the field decay is exponential with a
characteristic time of about 3$\times10^6$ yr. Observational data on single
X-ray pulsars which radiate due to cooling also support this result.


title:
The Lyman-alpha glow of gas falling into the dark matter halo of a z=3
  galaxy

abstract:
  Quasars are the visible signatures of super-massive black holes in the
centres of distant galaxies. It has been suggested that quasars are formed
during ``major merger events'' when two massive galaxies collide and merge,
leading to the prediction that quasars should be found in the centres of the
regions of largest overdensity in the early Universe. In dark matter
(DM)-dominated models of the early Universe, massive DM halos are predicted to
attract the surrounding gas, which falls towards its centre. The neutral gas is
not detectable in emission by itself, but gas falling into the ionizing cone of
such a quasar will glow in the Lyman-alpha line of hydrogen, effectively
imaging the DM halo. Here we present a Lyman-alpha image of a DM halo at
redshift 3, along with a two-dimensional spectrum of the gaseous halo. Our
observations are best understood in the context of the standard model for DM
halos; we infer a mass of (2-7) x 10^12 solar masses (Msun) for the halo.


title: Caught in the Act?

abstract:
  Which came first, the stars and gas that make up a galaxy, or the giant black
hole at its centre? Observations of a distant galaxy, caught as it forms, could
help solve this chicken-and-egg problem.


title: Properties of Young Massive Cluster Derived from Photometry

abstract:
  I will show that photometry -- if extending over a reasonable choice of
passbands -- can give fairly precise information about young star clusters and
their evolutionary state. Optical colors alone are known to leave severe
ambiguities due to degeneracies between age, metallicity and extinction. High
quality photometry including $U, B, V$ or $I$, and a NIR band, however, in
combination with an extensive grid of evolutionary synthesis models for star
clusters and a dedicated tool to analyse spectral energy distributions allows
to assess and largely disentangle star cluster ages, metallicities, extinction
values and, hence, to derive their masses. Gaseous emission contributions
sensibly affect broad band colors during the youngest stages, depending on
metallicity. Mass functions of young star cluster systems may considerably
differ in shape from luminosity functions. An ESO ASTROVIRTEL project provides
multi-color photometry for a large number of young, intermediate age and old
star cluster systems. As a first example I show results obtained for NGC 1569.


title: An Infrared Survey of Neutron-Capture Elements in Planetary Nebulae

abstract:
  We present results from an ongoing survey of infrared emission lines from the
neutron-capture elements Se and Kr in Galactic planetary nebulae (PNe). Se and
Kr may be produced in the initial steps of the s-process during the asymptotic
giant branch (AGB) phase of PN progenitor stars, and brought to the surface by
convective dredge-up before PN ejection. Therefore, enriched Se and Kr
abundances in PNe indicate that the s-process and dredge-up were active within
the progenitor stars. We have detected the emission lines [Kr III] 2.199 and
[Se IV] 2.287 microns in 68 of 119 Galactic PNe, and used these line fluxes to
derive ionic and total elemental abundances. Using the ionization correction
factors Se^{3+}/Se = Ar^{++}/Ar and Kr^{++}/Kr = S^{++}/S, we find a range of
Se and Kr abundances, from nearly solar to enriched by a factor of 5-10 times,
which implies varying degrees of dredge-up efficiency in the progenitor stars.
We have searched for correlations between n-capture element abundances and
other nebular properties, and find that PNe with Wolf-Rayet central stars tend
to exhibit more elevated Se and Kr abundances than other nebulae. Bipolar
nebulae, believed to arise from the most massive of PN progenitors, may have
lower n-capture abundances than elliptical PNe.


title:
High-Resolution NIR Observations of the Circumstellar Disk System in the
  Bok Globule CB 26

abstract:
  We report on results of near-infrared and optical observations of the mm disk
embedded in the Bok globule CB 26 (Launhardt & Sargent 2001). The near-infrared
images show a bipolar reflection nebula with a central extinction lane which
coincides with the mm disk. Imaging polarimetry of this object yielded a
polarization pattern which is typical for a young stellar object surrounded by
a large circumstellar disk and an envelope, seen almost edge-on. The strong
linear polarization in the bipolar lobes is caused by single scattering at dust
grains and allowed to locate the illuminating source which coincides with the
center of the mm disk. The spectral energy distribution of the YSO embedded in
CB 26 resembles that of a ClassI source with a luminosity of 0.5 L_sun.Using
the pre-main-sequence evolutionary tracks and the stellar mass inferred from
the rotation curve of the disk, we derive an age of the system of <10^6 yr.
H_alpha and [SII] narrow-band imaging as well as optical spectroscopy revealed
an Herbig-Haro object 6.15 arcmin northwest of CB 26 YSO 1, perfectly aligned
with the symmetry axis of the bipolar nebula. This Herbig-Haro object (HH 494)
indicates ongoing accretion and outflow activity in CB 26 YSO 1. Its excitation
characteristics indicate that the Herbig-Haro flow is propagating into a
low-density environment. We suggest that CB 26 YSO 1 represents the transition
stage between embedded protostellar accretion disks and more evolved
protoplanetary disks around T Tauri stars in an undisturbed environment.


title: The star formation history of Seyfert 2 nuclei

abstract:
  We present a study of the stellar populations in the central ~ 200 pc of a
large and homogeneous sample comprising 79 nearby galaxies, most of which are
type 2 Seyferts. The star-formation history of these nuclei is reconstructed by
means of state-of-the art population synthesis modeling of their spectra in the
3500--5200 A interval. A QSO-like featureless continuum (FC) is added to the
models to account for possible scattered light from a hidden AGN.
  We find that: (1) The star-formation history of Seyfert 2 nuclei is
remarkably heterogeneous: young starbursts, intermediate age, and old stellar
populations all appear in significant and widely varying proportions. (2) A
significant fraction of the nuclei show a strong FC component, but this FC is
not always an indication of a hidden AGN: it can also betray the presence of a
young, dusty starburst. (3) We detect weak broad Hbeta emission in several
Seyfert 2s after cleaning the observed spectrum by subtracting the synthesis
model. These are most likely the weak scattered lines from the hidden Broad
Line Region envisaged in the unified model, given that in most of these cases
independent spectropolarimetry data finds a hidden Seyfert 1. (4) The FC
strengths obtained by the spectral decomposition are substantially larger for
the Seyfert 2s which present evidence of broad lines, implying that the
scattered non-stellar continuum is also detected. (5) There is no correlation
between the star-formation in the nucleus and either the central or overall
morphology of the parent galaxies.


title: Cluster Survey Studies of the Dark Energy

abstract:
  Galaxy cluster surveys are power tools for studying the dark energy. In
principle, the equation of state parameter w of the dark energy and its time
evolution can be extracted from large solid angle, high yield surveys that
deliver tens of thousands of clusters. Robust constraints require accurate
knowledge of the survey selection, and crude cluster redshift estimates must be
available. A simple survey observable like the cluster flux is connected to the
underlying cluster halo mass through a so--called mass--observable relation.
The calibration of this mass--observable relation and its redshift evolution is
a key challenge in extracting precise cosmological constraints. Cluster survey
self--calibration is a technique for meeting this challenge, and it can be
applied to large solid angle surveys. In essence, the cluster redshift
distribution, the cluster power spectrum, and a limited number of mass
measurements can be brought together to calibrate the survey and study the dark
energy simultaneously. Additional survey information like the shape of the mass
function and its evolution with redshift can then be used to test the
robustness of the dark energy constraints.


title: Wolf-Rayet Stars as IMF Probes

abstract:
  Wolf-Rayet stars are the evolved descendents of massive stars. Their
extraordinary properties make them useful tracers of the stellar initial mass
function (IMF) in a young stellar population. I discuss how the interpretation
of spectral diagnostics are complicated by the interplay of stellar, nebular,
and dust properties. There is mounting observational evidence for spatial
inhomogeneities in the gas and dust distribution. The interplay of these
inhomogeneities can significantly alter frequently used star-formation and IMF
indicators. Specific examples presented in this contribution are the starburst
galaxies NGC 1614, NGC 2798, and NGC 3125.


title: The Cosmic Ray Muon Flux at WIPP

abstract:
  In this work a measurement of the muon intensity at the Waste Isolation Pilot
Plant (WIPP) near Carlsbad, NM, USA is presented. WIPP is a salt mine with a
depth of 655 m. The vertical muon flux was measured with a two panels
scintillator coincidence setup to
Phi_{vert}=3.10(+0.05/-0.07)*10^(-7)s^(-1)cm^(-2)sr^(-1).


title:
Radio Afterglows of Gamma-Ray Bursts and Hypernovae at High Redshift,
  and their Potential for 21-cm Absorption Studies

abstract:
  We investigate the radio afterglows of gamma-ray bursts (GRBs) and hypernovae
(HNe) at high redshifts and quantify their detectability, as well as their
potential usefulness for 21 cm absorption line studies of the intergalactic
medium (IGM) and intervening structures. We examine several sets of source and
environment model parameters that are physically plausible at high redshifts.
The radio afterglows of GRBs would be detectable out to z ~ 30, while the
energetic HNe could be detectable out to z ~ 20 even by the current Very Large
Array (VLA). We find that the 21 cm absorption line due to the diffuse neutral
IGM is difficult to detect even by the proposed Square Kilometer Array (SKA),
except for highly energetic sources. We also find that the 21 cm line due to
collapsed gas clouds with high optical depth may be detected on rare occasions.


title: Supersonic Motions of Galaxies in Clusters

abstract:
  We study motions of galaxies in galaxy clusters formed in the concordance
LCDM cosmology. We use high-resolution cosmological simulations that follow
dynamics of dark matter and gas and include various physical processes critical
for galaxy formation: gas cooling, heating and star formation. Analysing
motions of galaxies and the properties of intracluster gas in the sample of
eight simulated clusters at z=0, we study velocity dispersion profiles of the
dark matter, gas, and galaxies. We measure the mean velocity of galaxy motions
and gas sound speed as a function of radius and calculate the average Mach
number of galaxy motions. The simulations show that galaxies, on average, move
supersonically with the average Mach number of ~1.4, approximately independent
of the cluster-centric radius. The supersonic motions of galaxies may
potentially provide an important source of heating for the intracluster gas by
driving weak shocks and via dynamical friction, although these heating
processes appear to be inefficient in our simulations. We also find that
galaxies move faster than the dark matter particles in clusters. The magnitude
of the velocity bias, b_v~1.1, is, however, smaller than the bias estimated for
subhalos in dissipationless simulations. Interestingly, we find velocity bias
in the tangential component of the velocity dispersion, but not in the radial
component. Finally, we find significant random bulk motions of gas. The typical
gas velocities are of order ~20-30% of the gas sound speed. These random
motions provide about 10% of the total pressure support in our simulated
clusters. The non-thermal pressure support, if neglected, will bias
measurements of the total mass in the hydrostatic analyses of the X-ray cluster
observations.


title:
The spectrum of particles accelerated in relativistic, collisionless
  shocks

abstract:
  We analytically study diffusive particle acceleration in relativistic,
collisionless shocks. We find a simple relation between the spectral index s
and the anisotropy of the momentum distribution along the shock front. Based on
this relation, we obtain s = (3beta_u - 2beta_u*beta_d^2 + beta_d^3) / (beta_u
- beta_d) for isotropic diffusion, where beta_u (beta_d) is the upstream
(downstream) fluid velocity normalized to the speed of light. This result is in
agreement with previous numerical determinations of s for all (beta_u,beta_d),
and yields s=38/9 in the ultra-relativistic limit. The spectrum-anisotropy
connection is useful for testing numerical studies and for constraining
non-isotropic diffusion results. It implies that the spectrum is highly
sensitive to the form of the diffusion function for particles travelling along
the shock front.


title:
Studying The Star Formation Histories of Galaxies in Clusters from
  Composite Spectra

abstract:
  We have formed ``composite spectra'' by combining the integrated-light
spectra of individual galaxies in 8 intermediate-redshift and 12 low-redshift
clusters of galaxies. Because these composite spectra have much higher
signal-to-noise ratios than individual galaxy spectra, they are particularly
useful in quantifying general trends in star formation for galaxy populations
in distant clusters, z > 0.3. By measuring diagnostic features that represent
stellar populations of very different ages, a grand-composite spectrum can
reflect the fractions of those populations as accurately as if excellent
spectral measurements were available for each galaxy.
  Measuring the equivalent widths of spectral features in composite spectra is
especially well-suited for comparing cosmic variance of star formation in
clusters at a given redshift, or comparing clusters over a range of redshifts.
When we do this we find that [O II] emission and especially Balmer absorption
is strong in each of our intermediate-redshift clusters, and completely
separable from a sample of 12 present-epoch clusters, where these features are
weak. Specifically, we show by comparing to the H-delta strengths of
present-epoch populations of continuously star-forming galaxies that the
higher-redshift samples must contain a much higher fraction of starburst
galaxies than are found today in any environment.


title: Top 10 Problems on Massive Stars

abstract:
  We have asked a number of researchers to compile their lists of the top 10
problems in the field of massive stars. This paper is a compilation of these
lists. We attempted to survey observers and theorists and those studying all
evolutionary stages in the lives of massive stars. Each list reflects the
proposer's personal point of view, but hopefully, this compilation will
motivate new young astronomers and begin a new series of discussion.


title:
How black holes get their kicks: Radiation recoil in binary black hole
  mergers

abstract:
  Gravitational waves from the coalescence of binary black holes carry linear
momentum, causing center of mass recoil. This ``radiation rocket'' has
important implications for systems with escape speeds of order the recoil
velocity. We describe new recoil calculations using high precision black hole
perturbation theory to estimate the magnitude of the recoil for the slow
``inspiral'' coalescence phase; coupled with a cruder calculation for the final
``plunge'', we estimate the total recoil imparted to a merged black hole. We
find that velocities of many tens to a few hundred km/sec can be achieved
fairly easily. The recoil probably never exceeds about 500 km/sec.


title: The spectrum features of UHECRs below and surrounding GZK

abstract:
  The energy spectrum of UHECRs is discussed on the basis of the Yakutsk array
database analysis. In the region E=0.1 to 30 EeV the showers are detected under
trigger-500, while at energies above 30 EeV the whole acceptance area for
trigger-1000 is used in order to utilize all the data available in the region
of GZK cutoff.


title: The BAT-Swift Science Software

abstract:
  The BAT instrument tells the Swift satellite where to point to make immediate
follow-up observations of GRBs. The science software on board must efficiently
process gamma-ray events coming in at up to 34 kHz, identify rate increases
that could be due to GRBs while disregarding those from known sources, and
produce images to accurately and rapidly locate new Gamma-ray sources.


title: Can vacuum decay in our Universe?

abstract:
  We take a phenomenological approach to study the cosmological evolution of
decaying vacuum cosmology ($\Lambda(t)$CDM) based on a simple assumption about
the form of the modified matter expansion rate. In this framework, almost all
the current vacuum decaying models can be unified in a simple manner. We argue
that the idea of letting vacuum decay to resolve the fine-tuning problem is
inconsistent with cosmological observations. We also discuss some issues in
confronting $\Lambda(t)$CDM with observation. Using the effective equation of
state formalism, we indicate that $\Lambda(t)$CDM is a possible candidate for
phantom cosmology. Moreover, confronted with a possible trouble of effective
equation of state formalism, we construct the effect dark energy density.
Finally, we discuss the evolution of linear perturbation.


title: Electric field screening by a proton counterflow in the pulsar polar cap

abstract:
  We propose a new mechanism to screen the electric field in the pulsar polar
cap. Previous studies have shown that if an electron beam from the stellar
surface is accelerated to energies high enough to create electron-positron
pairs, the required electric field parallel to the magnetic field lines is too
strong to be screened out by the produced pairs. We argue here that if
non-relativistic protons are supplied from the magnetosphere to flow towards
the stellar surface, they can provide an anode to screen out such a strong
electric field. Injected electron-positron pairs yield an asymmetry of the
electrostatic potential around the screening point. The required pair creation
rate in this model is consistent with the conventional models.


title:
Radial Variation of Optical and Near-Infrared Colours in Luminous
  Early-Type Galaxies in ABELL 2199

abstract:
  We performed K band surface photometry for luminous early-type galaxies in a
nearby rich cluster ABELL 2199. Combining it with B and R band surface
photometry, radial variations of B-R and R-K colours in the galaxies were
investigated. It is found that the inner regions of the galaxies are redder in
both of B-R and R-K colours. Comparing the radial variations of both of the
colours with predictions of Simple Stellar Population (SSP) models for a range
of ages and metallicities, it is suggested that the cluster ellipticals have
negative metallicity gradients but their age gradients are consistent with
zero, although our sample is small; the typical metallicity gradient is
estimated to be -0.16+- 0.09 in dlogZ/dlogr, while the age gradient is
estimated to be -0.10 +- 0.14 in dlog(age)/dlogr. Considering that similar
results have also been derived in the other recent studies using samples of
ellipticals in the Coma cluster and less dense environments, it seems that
there is no strong dependence on galaxy environment in radial gradient of
stellar population in elliptical galaxy.


title: Effects of Thermal Fluctuations in the SPOrt Experiment

abstract:
  The role of systematic errors induced by thermal fluctuations is analyzed for
the SPOrt experiment with the aim at estimating their impact on the measurement
of the Cosmic Microwave Background Polarization (CMBP). The transfer functions
of the antenna devices from temperature to data fluctuations are computed, by
writing them in terms of both instrument and thermal environment parameters. In
addition, the corresponding contamination maps are estimated, along with their
polarized power spectra, for different behaviours of the instabilities. The
result is that thermal effects are at a negligible level even for fluctuations
correlated with the Sun illumination provided their frequency $f_{tf}$ is
larger than that of the Sun illumination ($f_{day}$) by a factor $f_{tf} /
f_{day} > 30$, which defines a requirement for the statistical properties of
the temperature behaviour as well. The analysis with actual SPOrt operative
parameters shows that the instrument is only weakly sensitive to temperature
instabilities, the main contribution coming from the cryogenic stage. The
contamination on the E-mode spectrum does not significantly pollute the CMBP
signal and no specific data cleaning seems to be needed.


title:
The "missing link": a 4-day period transiting exoplanet around
  OGLE-TR-111

abstract:
  We report the discovery of a transiting hot Jupiter around OGLE-TR-111, from
our radial velocity follow-up of OGLE transiting candidates in Carina. The
planet has a mass of 0.53 +- 0.11 M_J and a radius of 1.0 +0.13-0.06 R_J. Three
transiting exoplanets have already been found among OGLE candidates, all with
periods near 1.5 days. The planet presented here, with P=4.0 days, is the first
exoplanet detected by transits with the characteristics of a "normal" hot
Jupiter, as found in abundance by radial velocity surveys The radius of
OGLE-TR-111b and the scarcity of hot Jupiters detected among OGLE transit
candidates tend to indicate that the case of HD209458b, with a radius of 1.4
R_J, is exceptional, with most hot Jupiters being smaller.


title: Multiwavelength Study Of Two Unidentified Gamma-ray Sources

abstract:
  Most counterparts of the identified low-latitude gamma-ray sources are
Isolated Neutron Stars (INSs). They are characterized by an extremely high
value of the X/optical flux ratio, therefore a systematic X-ray/optical
coverage of the fields of unidentified low-latitude gamma-ray sources is the
best way to unveil possible INS counterparts. Since the low-latitude sources
are heavily affected by the interstellar absorption in both the X-ray and
optical bands, we decided to apply the above strategy to two middle-latitude
EGRET sources, which could belong to a local galactic population: 3EG
J0616-3310 and 3EG J1249-8330. Here we report on the global X-ray
characterisation of about 300 objects, on their candidate optical counterparts
and on the preliminary results of their identification.


title: The gas temperature in the surface layers of protoplanetary disks

abstract:
  Models for the structure of protoplanetary disks have so far been based on
the assumption that the gas and the dust temperature are equal. The gas
temperature, an essential ingredient in the equations of hydrostatic
equilibrium of the disk, is then determined from a continuum radiative transfer
calculation, in which the continuum opacity is provided by the dust. It has
been long debated whether this assumption still holds in the surface layers of
the disk, where the dust infrared emission features are produced. In this paper
we compute the temperature of the gas in the surface layers of the disk in a
self-consistent manner. The gas temperature is determined from a
heating-cooling balance equation in which processes such as photoelectric
heating, dissociative heating, dust-gas thermal heat exchange and line cooling
are included. The abundances of the dominant cooling species such as CO, C, C+
and O are determined from a chemical network based on the atomic species H, He,
C, O, S, Mg, Si, Fe (Kamp & Bertoldi 2000). The underlying disk models to our
calculations are the models of Dullemond, van Zadelhoff & Natta (2002). We find
that in general the dust and gas temperature are equal to withing 10% for A_V
>~ 0.1, which is above the location of the `super-heated surface layer' in
which the dust emission features are produced (e.g. Chiang & Goldreich 1997).
High above the disk surface the gas temperature exceeds the dust temperature
and can can become -- in the presence of polycyclic aromatic hydrocarbons -- as
high as 600 K at a radius of 100 AU. This is a region where CO has fully
dissociated, but a significant fraction of hydrogen is still in molecular form.
The densities are still high enough for non-negligible H_2 emission to be
produced.....(see paper for full abstract)


title:
Properties of Molecular Gas in Massive Low Surface Brightness Galaxies,
  Including New 12CO Observations of Three Malin 1 `Cousins'

abstract:
  To date, the only low surface brightness (LSB) galaxies which have been
detected in CO are the Massive LSB (MLSB) galaxies. In 2003, O'Neil,
Schinnerer, & Hofner hypothesized that is the prominent bulge component in MLSB
galaxies, not present in less massive low surface brightness galaxies, which
gives rise to the detectable quantities of CO gas. To test this hypothesis, we
have used the IRAM 30m telescope to obtain three new, deep CO J(1-0) and J(2-1)
observations of MLSB galaxies. Two of the three galaxies observed were detected
in CO - one in the J(1-0) line and the other in both the J(1-0) and J(2-1)
lines, bringing the total number of MLSB galaxies with CO detections to 5, out
of a total of 9 MLSB galaxies observed at CO to date. The third object had no
detection to 2 mK at CO J(1-0). Comparing all MLSB galaxy CO results with
surveys of high surface brightness galaxies, we find the MLSB galaxies' MH2 and
MH2/MHI values fall within the ranges typically found for high surface
brightness objects, albeit at the low end of the distribution, with the two
MLSB galaxies detected at CO in this survey having the highest MH2/MHI values
yet measured for any LSB system, by factors of 2-3.


title: The gas temperature in flaring disks around pre-main sequence stars

abstract:
  A model is presented which calculates the gas temperature and chemistry in
the surface layers of flaring circumstellar disks using a code developed for
photon-dominated regions. Special attention is given to the influence of dust
settling. It is found that the gas temperature exceeds the dust temperature by
up to several hundreds of Kelvins in the part of the disk that is optically
thin to ultraviolet radiation, indicating that the common assumption that
Tgas=Tdust is not valid throughout the disk. In the optically thick part, gas
and dust are strongly coupled and the gas temperature equals the dust
temperature. Dust settling has little effect on the chemistry in the disk, but
increases the amount of hot gas deeper in the disk. The effects of the higher
gas temperature on several emission lines arising in the surface layer are
examined. The higher gas temperatures increase the intensities of molecular and
fine-structure lines by up to an order of magnitude, and can also have an
important effect on the line shapes.


title:
An Empirical Algorithm for Broad-band Photometric Redshifts of Quasars
  from the Sloan Digital Sky Survey

abstract:
  We present an empirical algorithm for obtaining photometric redshifts of
quasars using 5-band Sloan Digital Sky Survey (SDSS) photometry. Our algorithm
generates an empirical model of the quasar color-redshift relation, compares
the colors of a quasar candidate with this model, and calculates possible
photometric redshifts. Using the 3814 quasars of the SDSS Early Data Release
Quasar Catalog to generate a median color-redshift relation as a function of
redshift we find that, for this same sample, 83% of our predicted redshifts are
correct to within |Delta z|<0.3. The algorithm also determines the probability
that the redshift is correct, allowing for even more robust photometric
redshift determination for smaller, more restricted samples. We apply this
technique to a set of 8740 quasar candidates selected by the final version of
the SDSS quasar-selection algorithm. The photometric redshifts assigned to
non-quasars are restricted to a few well-defined values. In addition, 90% of
the objects with spectra that have photometric redshifts between 0.8 and 2.2
are quasars with accurate (|Delta z|<0.3) photometric redshifts. Many of these
quasars lie in a single region of color space; judicious application of
color-cuts can effectively select quasars with accurate photometric redshifts
from the SDSS database. When the SDSS is complete, this technique will allow
the determination of photometric redshifts for ~10^6 faint SDSS quasar
candidates, enabling advances in our knowledge of the quasar luminosity
function, gravitational lensing of quasars, and correlations among quasars and
between galaxies.


title:
Efficient Photometric Selection of Quasars from the Sloan Digital Sky
  Survey: 100,000 z<3 Quasars from Data Release One

abstract:
  We present a catalog of 100,563 unresolved, UV-excess (UVX) quasar candidates
to g=21 from 2099 deg^2 of the Sloan Digital Sky Survey (SDSS) Data Release One
(DR1) imaging data. Existing spectra of 22,737 sources reveals that 22,191
(97.6%) are quasars; accounting for the magnitude dependence of this
efficiency, we estimate that 95,502 (95.0%) of the objects in the catalog are
quasars. Such a high efficiency is unprecedented in broad-band surveys of
quasars. This ``proof-of-concept'' sample is designed to be maximally
efficient, but still has 94.7% completeness to unresolved, g<~19.5, UVX quasars
from the DR1 quasar catalog. This efficient and complete selection is the
result of our application of a probability density type analysis to training
sets that describe the 4-D color distribution of stars and spectroscopically
confirmed quasars in the SDSS. Specifically, we use a non-parametric Bayesian
classification, based on kernel density estimation, to parameterize the color
distribution of astronomical sources -- allowing for fast and robust
classification. We further supplement the catalog by providing photometric
redshifts and matches to FIRST/VLA, ROSAT, and USNO-B sources. Future work
needed to extend the this selection algorithm to larger redshifts, fainter
magnitudes, and resolved sources is discussed. Finally, we examine some science
applications of the catalog, particularly a tentative quasar number counts
distribution covering the largest range in magnitude (14.2<g<21.0) ever made
within the framework of a single quasar survey.


title: O VII and O VIII absorption by hot gas in the vicinity of the Galaxy

abstract:
  (abridged) We searched for evidence of soft X-ray absorption by hot gas in
the vicinity of the Galaxy in a small sample of fifteen type I AGN observed
with the high resolution X-ray gratings on board Chandra. We find that around
half of the sight lines in our sample exhibit absorption due to local H- or
He-like Oxygen (or both) at confidence levels ranging from >90% to >3sigma.
Depending on the sight line, the absorption can be identified with hot gas in
particular local structures, the Local Group (LG) or the putative local hot
intergalactic medium (IGM). Several sight lines in our sample coincide with
sight lines in a study of O VI absorption by local gas, so an assumption of
collisional ionization equilibrium (CIE) allows us to constrain the temperature
of the local hot gas. We show that some portion of the hot absorbing outflows
apparently detected in the spectra of NGC 4051, PDS 456 and PG 1211+143
respectively could actually correspond to absorption by hot local gas since the
outflow velocity from each of these AGN coincides with the respective
cosmological recession velocity of the AGN.


title: The narrow-line quasar NAB 0205+024 observed with XMM-Newton

abstract:
  The XMM-Newton observation of the narrow-line quasar NAB 0205+024 reveals
three striking differences since it was last observed in the X-rays with ASCA.
Firstly, the 2-10 keV power-law is notably steeper. Secondly, a hard X-ray
flare is detected, very similar to that seen in I Zw 1. Thirdly, a strong and
broad emission feature is detected with the bulk of its emission redward of 6.4
keV, and extending down to ~5 keV in the rest frame. The most likely
explanation for the broad feature is neutral iron emission emitted from a
narrow annulus of an accretion disc close to the black hole. The hard X-ray
flare could be the mechanism which illuminates this region of the disc,
allowing for the emission line to be detected. The combination of effects can
be understood in terms of the `thundercloud' model proposed by Merloni &
Fabian.


title: Circumstellar interaction of the type Ia supernova 2002ic

abstract:
  We propose a model to account for the bolometric light curve, quasi-continuum
and the Ca II emission features of the peculiar type Ia supernova (SN) 2002ic,
which exploded in a dense circumstellar envelope. The model suggests that the
SN Ia had the maximum possible kinetic energy and that the ejecta expand in an
approximately spherically symmetric (possibly clumpy) circumstellar
environment. The Ca II and quasi-continuum are emitted by shocked SN ejecta
that underwent deformation and fragmentation in the intershock layer. Modeling
of the Ca II triplet implies that the contribution of the O I 8446 A line is
about 25% of the 8500 A feature on day 234, which permits us to recover the
flux in the Ca II 8579 A triplet from the flux of 8500 A blend reported by Deng
et al. (2004). We use the Ca II doublet and triplet fluxes on day 234 to derive
the electron temperature (~4400 K) in the Ca II line-emitting zone and the
ratio of the total area of dense fragments to the area of the shell, S/S_0 ~
100. We argue that Ca II bands and quasi-continuum originate from different
zones of the shocked ejecta that reflect the abundance stratification of the
supernova.


title: The abundance of HOC+ in diffuse clouds

abstract:
  We used the Plateau de Bure Interferometer to search for $\lambda$3mm
absorption lines of HOC+ from local diffuse and translucent clouds occulting
compact extragalactic mm-wave continuum sources. We detected HOC+ in three
directions with column densities only 70-120 times below those of the HCO+
isomer, a factor 5-50 higher than typically found in dense dark gas but
comparable to recent observations of dense photon-dominated regions. The
observed amounts of HOC+, N(HOC+)/N(\HH) $ = 3-6\times 10^{-11} $, can be made
in quiescent diffuse gas at thermal gas-kinetic rates if the {\HH O}/OH ratio
is of order unity, in mild violation of extant observational limits. %


title: Nonlinear Scale Invariance in Local Disk Flows

abstract:
  An exact nonlinear scaling transformation is presented for the local
three-dimensional dynamical equations of motion for differentially rotating
disks. The result is relevant to arguments that have been put forth claiming
that numerical simulations lack the necessary numerical resolution to resolve
nonlinear instabilities that are supposedly present. We show here that any time
dependent velocity field satisfying the local equations of motion and existing
on small length scales, has an exact rescaled counterpart that exists on
arbitrarily larger scales as well. Large scale flows serve as a microscope to
view small scale behavior. The absence of any large scale instabilities in
local numerical simulations of Keplerian disks suggests that the equations in
this form have no instabilities at any scale, and that finite Reynolds number
suppression is not the reason for the exhibited stable behavior. While this
argument does not rule out the possibility of global hydrodynamical
instability, it does imply that differential rotation {\em per se} is not
unstable in a manner analogous to shear layers or high Reynolds number
Poiseuille flow. Analogies between the stability behavior of accretion disks
and these flows are specious.


title:
The influence of rotation in radiation driven winds from hot stars II.
  CAK topological analysis

abstract:
  The topological analysis from Bjorkman (1995) for the standard model that
describes the winds from hot stars by Castor, Abbott & Klein (1975) has been
extended to include the effect of stellar rotation and changes in the
ionization of the wind. The differential equation for the momentum of the wind
is non--linear and transcendental for the velocity gradient. Due to this
non--linearity the number of solutions that this equation possess is not known.
After a change of variables and the introduction of a new physically
meaningless independent variable, we manage to replace the non--linear momentum
differential equation by a system of differential equations where all the
derivatives are {\it{explicitely}} given. We then use this system of equations
to study the topology of the rotating--CAK model. For the particular case when
the wind is frozen in ionization ($\delta=0$) only one physical solution is
found, the standard CAK solution, with a X--type singular point. For the more
general case ($\delta \neq 0$), besides the standard CAK singular point, we
find a second singular point which is focal--type (or attractor). We find also,
that the wind does not adopt the maximal mass--loss rate but almost the
minimal.


title: Setting the Triggering Threshold on Swift

abstract:
  Swift has two main types of ``rate'' triggers: short and long. Short trigger
time scales range from 4ms to 64ms, while long triggers are 64ms to ~ 16
seconds. While both short and long trigger have criteria with one background
sample (traditional ``one-sided'' triggers), the long triggers can also have
criteria with two background samples (``bracketed'' triggers) which remove
trends in the background. Both long and short triggers can select energy ranges
of 15-25, 15-50, 25-100 and 50-350 KeV. There are more than 180 short
triggering criteria and approximately 500 long triggering criteria used to
detect gamma ray bursts. To fully utilize these criteria, the thresholds must
be set correctly. The optimum thresholds are determined by a tradeoff between
avoiding false triggers and capturing as many bursts as possible. We use
realistic simulated orbital variations, which are the prime cause of false
triggers.


title: Swift's Ability to Detect Gamma-Ray Bursts

abstract:
  The Swift satellite will be a self-contained observatory that will bring new
capabilities to the observing of the early afterglow emission of Gamma-ray
Bursts. Swift is completely autonomous and will do all of the observations
without help from the ground. There are three instruments on Swift. A large
(5200 sq cm) coded aperture imager will locate the bursts within about 15
seconds. The satellite will be able to slew to point at the location within a
minute or two. There are two narrow field of view instruments: an optical
telescope and an x-ray telescope. Thus, Swift will provide simultaneous
gamma-ray, x-ray, and optical observations of Gamma-ray bursts soon after the
burst. A key to the success of Swift will be its ability to detect and locate a
large number of gamma-ray bursts quick enough that the narrow field of view
instruments can follow up. The results of simulations show that Swift will be
able to detect about 300 bursts a year and locate about 150. The number that
Swift will be able to slew to depends on constraints built into the satellite
bus. Preliminary results indicate that we might be able to slew to 100 bursts
per year, but that is heavily dependent on satellite operations.


title: The Trigger Algorithm for the Burst Alert Telescope on Swift

abstract:
  The Swift Burst Alert Telescope (BAT) is a huge (5200 cm2) coded aperture
imager that will detect gamma-ray bursts in real time and provide a location
that the Swift satellite will use to slew the optical and x-ray telescopes. The
huge size of BAT is a challenge for the on-board triggering: a change as small
as 1% is equivalent to a 1 sigma statistical variation in 1 second. There will
be three types of triggers, two based on rates and one based on images. The
first type of trigger is for short time scales (4 msec to 64 msec). These will
be traditional triggers (single background) and we check about 25,000
combinations of time-energy-focal plane subregions per second. The second type
of trigger will be similar to what is used on HETE: fits to multiple background
regions to remove trends for time scales between 64 msec and 64 seconds. About
500 triggers will be checked per second. For these rate triggers, false
triggers and variable non-GRB sources will be rejected by requiring a new
source to be present in an image. The third type of trigger works on longer
time scales (minutes), and will be based on routine images that are made of the
field of view.


title:
Multifrequency analysis of 21 cm fluctuations from the Era of
  Reionization

abstract:
  We study the prospects for extracting detailed statistical properties of the
neutral Hydrogen distribution during the era of reionization using the
brightness temperature fluctuations from redshifted 21 cm line emission.
Detection of this signal is complicated by contamination from foreground
sources such as diffuse Galactic synchrotron and free-free emission at low
radio frequencies, extragalactic free-free emission from ionized regions and
radio point sources. We model these foregrounds to determine the extent to
which 21 cm fluctuations can be detected with upcoming experiments. We find
that not only the level of correlation from one frequency to another, but also
the functional form of the foreground correlations has a substantial impact on
foreground removal. We calculate how well the angular power spectra of the 21cm
fluctuations can be determined. We also show that the large-scale bias of the
neutral Hydrogen gas distribution with respect to the density field, can be
determined with high precision and used to distinguish between different
reionization histories.


title:
Cosmic Star Formation History to z=1 from a Narrow Emission Line
  Selected Tunable Filter Survey

abstract:
  We report the results of a deep 3D imaging survey of the Hubble Deep Field
North using the Taurus Tunable Filter and the William Herschel Telescope. This
survey was designed to search for new line emitting populations of objects
missed by other techniques and to measure the cosmic star-formation rate
density from a line-selected survey. We observed in three contiguous sequences
of narrow band slices in the 7100, 8100 and 9100A regions of the spectrum,
corresponding to a cosmological volume of up to 1000 Mpc^3 at z=1, down to a
flux limit of 2x 10^-17 ergs cm^-2 s^-1. The survey is deep enough to be highly
complete for low line luminosity galaxies. Cross-matching with existing
spectroscopy in the field results in a small line-luminosity limited sample,
with very highly redshift identification completeness containing seven [OII],
Hbeta and Halpha emitters over the redshift range 0.3 - 0.9. Treating this as a
direct star-formation rate selected sample we estimate the star-formation
history of the Universe to z=1. We find no evidence for any new population of
line emitting objects contributing significantly to the cosmological
star-formation rate density. Rather from our complete narrow-band sample we
find the star-formation history is consistent with earlier estimates from
broad-band imaging surveys and other less deep line-selected surveys.


title: FeII/MgII Emission Line Ratios of QSOs. II. z>6 Objects

abstract:
  Near-infrared spectra of four QSOs located at $z>6$ are obtained with the
OH-airglow suppressor mounted on the Subaru telescope. The FeII/MgII
emission-line ratios of these QSOs are examined by the same fitting algorithm
as in our previous study of $z<5.3$ QSOs. The fitting results show that two out
of the four $z>6$ QSOs have significant FeII emission in their rest-UV spectra,
while the other two have almost no FeII features. We also applied our fitting
algorithm to more than 10,000 SDSS QSOs and found two trends in the
distribution of FeII/MgII against redshift: (1) the upper envelope of the
FeII/MgII distribution at $z>3$ shows a probable declination toward high
redshift, and (2) the median distribution settles into lower ratios at $z\sim
1.5$ with small scatter compared to the other redshift. We discuss an Fe/Mg
abundance evolution of QSOs with a substantial contribution from the diverse
nature of the broad-line regions in high-redshift QSOs.


title: Large Scale CO and [CI] emission in the rho Ophiuchi Molecular Cloud

abstract:
  We present a comprehensive study of the rho Ophiuchi molecular cloud that
addresses aspects of the physical structure and condition of the molecular
cloud and its photodissociation region (PDR) by combining far-infrared and
submillimeter-wave observations with a wide range of angular scale and
resolution. We present 40'x40' maps in CO(4-3) and [CI](3P1-3P0) line emission
from the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO), and
pointed observations in the CO(7-6) and [CI](3P2-3P1) lines. Within, smaller
spectral line maps of the cloud in CO, CS, HCO+ and their rare isotopomers are
made at the Heinrich Hertz Submillimeter Telescope Observatory (HHT) in
Arizona. Comparison with far-infrared and submillimeter continuum emission, and
near-infrared H2 emission allows clearer determination of the physical and
chemical structure of the rho Oph photodissociation region (PDR). The
excitation conditions needed to produce the observed HCO+ and [OI] emission
directly imply inhomogeneous structure. Strong chemical gradients are observed
in HCO+ and CS; the former is ascribed to a local enhancement in the H2
ionization rate, the latter is principally due to shocks. The distribution of
[CI] is very similar to C18O, and generally consistent with illumination from
the 'far' side of the cloud. A notable exception is found at the the western
edge of the cloud, where UV photons create a PDR viewed `edge-on'. The
abundance of atomic carbon is accurately modeled using a radiation field that
decreases with increasing projected distance from the exciting star HD147889.
In contrast to conclusions of other studies, we find that no non-equilibrium
chemistry is needed to enhance the atomic carbon abundance.


title: The New Interpretation of the Uniformly Expanding Universe

abstract:
  The spacetime structure of the spatially uniformly expanding universe is
described in terms of a kind of global space and global time instead of the
space and time we usually recognize. The global space at some instant is a
space in which the global time is equal and the global time is equal to the
proper time of any point moving together with the expansion of the universe
which has elapsed since the big bang. The universe descibed in terms of the
global space and time thus defined is open spatially and the Einstein's
equations give a solution that the space expands eternally regardless of the
mass density of the universe indicating that any expanding universe is open
dynamically as well, as it is the case only when the density is less than the
critical value in the standard model. In fact the critical density has not any
particular meaning in the new frame. Finally the equations for the light path
in the new frame are studied and are found similar to those in the standard
model.


title: Discovery of six Ly alpha emitters near a radio galaxy at z ~ 5.2

abstract:
  We present the results of narrow-band and broad-band imaging with the Very
Large Telescope of the field surrounding the radio galaxy TN J0924-2201 at z =
5.2. Fourteen candidate Ly alpha emitters with a rest-frame equivalent width of
> 20 A were detected. Spectroscopy of 8 of these objects showed that 6 have
redshifts similar to that of the radio galaxy. The density of emitters at the
redshift of the radio galaxy is estimated to be a factor 1.5-6.2 higher than in
the field, and comparable to the density of Ly alpha emitters in radio galaxy
protoclusters at z = 4.1, 3.1 and 2.2. The Ly alpha emitters near TN J0924-2201
could therefore be part of a structure that will evolve into a massive cluster.
These observations confirm that substantial clustering of Ly alpha emitters
occurs at z > 5 and support the idea that radio galaxies pinpoint high density
regions in the early Universe.


title: "Permanence" - An Adaptationist Solution to Fermi's Paradox?

abstract:
  A new solution of Fermi's paradox sketched by SF writer Karl Schroeder in his
2002. novel "Permanence" is critically investigated. It is argued that this
solution is tightly connected with adaptationism - a widely discussed working
hypothesis in evolutionary biology. Schroeder's hypothesis has important
ramifications for astrobiology, SETI projects, and future studies. Its
weaknesses should be explored without succumbing to the emotional reactions
often accompanying adaptationist explanations.


title:
The Formation of Free-Floating Brown Dwarves and Planetary-Mass Objects
  by Photo-Erosion of Prestellar Cores

abstract:
  We explore the possibility that, in the vicinity of an OB star, a prestellar
core which would otherwise have formed an intermediate or low-mass star may
form a free-floating brown dwarf or planetary-mass object, because the outer
layers of the core are eroded by the ionizing radiation from the OB star before
they can accrete onto the protostar at the centre of the core. The masses of
objects formed in this way are given approximately by $\sim 0.010 M_\odot
(a_{\rm I} / 0.3 {\rm km} {\rm s}^{-1})^6 (\dot{\cal N}_{\rm Lyc} / 10^{50}
{\rm s}^{-1})^{-1/3} (n_{\rm 0} / 10^3 {\rm cm}^{-3})^{-1/3} $, where $a_{\rm
I}$ is the isothermal sound speed in the neutral gas of the core, $\dot{\cal
N}_{\rm Lyc}$ is the rate of emission of Lyman continuum photons from the OB
star (or stars), and $n_{\rm 0}$ is the number-density of protons in the HII
region surrounding the core. We conclude that the formation of low-mass objects
by this mechanism should be quite routine, because the mechanism operates over
a wide range of conditions ($10^{50} {\rm s}^{-1} \la \dot{\cal N}_{\rm Lyc}
\la 10^{52} {\rm s}^{-1}$, $10 {\rm cm}^{-3} \la n_0 \la 10^5 {\rm cm}^{-3}$,
$0.2 {\rm km} {\rm s}^{-1} \la a_{\rm I} \la 0.6 {\rm km} {\rm s}^{-1}$) and is
very effective. However, it is also a rather wasteful way of forming low-mass
objects, in the sense that it requires a relatively massive initial core to
form a single low-mass object. The effectiveness of photo-erosion also implies
that that any intermediate-mass protostars which have formed in the vicinity of
a group of OB stars must already have been well on the way to formation before
the OB stars switched on their ionizing radiation; otherwise these protostars
would have been stripped down to extremely low mass.


title: Big Bang Nucleosynthesis with a New Neutron Lifetime

abstract:
  We show that the predicted primordial helium production is significantly
reduced when new measurements of the neutron lifetime and the implied
enhancement in the weak reaction rates are included in big-bang
nucleosynthesis. Therefore, even if a narrow uncertainty in the observed helium
abundance is adopted, this brings the constraint on the baryon-to-photon ratio
from BBN and the observed helium into better accord with the independent
determination of the baryon content deduced from the WMAP spectrum of power
fluctuations in the cosmic microwave background,and measurements of primordial
deuterium in narrow-line quasar absorption systems at high redshift.


title: A top-down scenario for the formation of massive Tidal Dwarf Galaxies

abstract:
  Among those objects formed out of collisional debris during galaxy mergers,
the prominent gaseous accumulations observed near the tip of some long tidal
tails are the most likely to survive long enough to form genuine recycled
galaxies. Using simple numerical models, Bournaud, Duc & Masset (2003) claimed
that tidal objects as massive as 10^9 Msun could only form, in these
simulations, within extended dark matter (DM) haloes. We present here a new set
of simulations of galaxy collisions to further investigate the structure of
tidal tails. First of all, we checked that massive objects are still produced
in full N-body codes that include feedback and a large number of particles.
Using a simpler N-body code with rigid haloes, we noticed that dissipation and
self-gravity in the tails, although important, are not the key factors.
Exploiting toy models, we found that, for truncated DM haloes, material is
stretched along the tail, while, within extended haloes, the tidal field can
efficiently carry away from the disk a large fraction of the gas, while
maintaining its surface density to a high value. This creates a density
enhancement near the tip of the tail. Only later-on, self-gravity takes over;
the gas clouds collapse and start forming stars. Thus, such objects were
fundamentally formed following a kinematical process, according to a top-down
scenario, contrary to the less massive Super Star Clusters that are also
present around mergers. This conclusion leads us to introduce a restrictive
definition for Tidal Dwarf Galaxies (TDGs) and their progenitors, considering
only the most massive ones, initially mostly made of gas, that were able to
pile up in the tidal tails. More simulations will be necessary to precisely
determine the fate of these proto--TDGs and estimate their number.


title: Protostellar Disks: Formation, Fragmentation, and the Brown Dwarf Desert

abstract:
  We argue that gravitational instability of typical protostellar disks is not
a viable mechanism for the fragmentation into multiple systems -- binary stars,
brown dwarf companions, or gas giant planets -- except at periods above roughly
20,000 years. Our conclusion is based on a comparison between prior numerical
work on disk self-gravity by Gammie (2001) with our own analytical models for
the dynamical and thermal state of protostellar disks. For this purpose we
first develop a simple theory for the initial conditions of low-mass star
formation, accounting for the effect of turbulence on the characteristic mass,
accretion rate, and angular momentum of collaping cores. Second, we examine the
criterion for fragmentation to occur during star formation, concentrating on
the self-gravitational instabilities of protostellar accretion disks in their
main accretion phase. Self-gravitational instabilities are strongly dependent
on the thermal state of the disk, and we find that the combination of viscous
heating and stellar irradiation quenches fragmentation due to Toomre's local
instability. Global instability of the disk may be required to process mass
supply, but is unlikely to produce fragments. Our findings help to explain the
dearth of substellar companions to stellar type stars: the brown dwarf desert.


title: The Luminous Erupting Dwarf Nova CV1 in the Dense Globular Cluster M15

abstract:
  Despite decades-old predictions of the expected presence of dozens of
cataclysmic variables in the cores of globular clusters, the number of
irrefutable, out-bursting candidates is still barely a handful. Using
multi-wavelength, multi-epoch HST images we have produced outburst and
quiescence light curves for the recently discovered large amplitude variable
CV1 in the core of the post core-collapse globular cluster M15. The light
curves and blue colors show that the object is a bona fide dwarf nova, with
absolute magnitude at maximum light rivaling that of the most luminous known
dwarf novae.


title: Diffusive Shock Acceleration in Unmodified Relativistic, Oblique Shocks

abstract:
  We present results from a fully relativistic Monte Carlo simulation of
diffusive shock acceleration (DSA) in unmodified shocks. The computer code uses
a single algorithmic sequence to smoothly span the range from nonrelativistic
speeds to fully relativistic shocks of arbitrary obliquity, providing a
powerful consistency check. While known results are obtained for
nonrelativistic and ultra-relativistic parallel shocks, new results are
presented for the less explored trans- relativistic regime and for oblique,
fully relativistic shocks. We find, for a wide trans-relativistic range
extending to shock Lorentz factors >30, that the particle spectrum produced by
DSA varies strongly from the canonical f(p) proportional to p^{-4.23} spectrum
known to result in ultra-relativistic shocks. Trans- relativistic shocks may
play an important role in gamma-ray bursts and other sources and most
relativistic shocks will be highly oblique.


title:
Initial Results from the Palomar Adaptive Optics Survey of Young
  Solar-Type Stars: a Brown Dwarf and Three Stellar Companions

abstract:
  We present first results from the Palomar Adaptive Optics Survey of Young
Stars conducted at the Hale 5 m telescope. Through direct imaging we have
discovered a brown dwarf and two low-mass stellar companions to the young
solar-type stars HD 49197, HD 129333 (EK Dra), and V522 Per, and confirmed a
previously suspected companion to RX J0329.1+0118 (Sterzik et al. 1997), at
respective separations of 0.95" (43 AU), 0.74" (25 AU), 2.09" (400 AU), and
3.78" (380 AU). Physical association of each binary system is established
through common proper motion and/or low-resolution infrared spectroscopy. Based
on the companion spectral types, we estimate their masses at 0.06, 0.20, 0.13,
and 0.20 Msun, respectively. From analysis of our imaging data combined with
archival radial velocity data, we find that the spatially resolved companion to
HD 129333 is potentially identical to the previously identified spectroscopic
companion to this star (Duquennoy & Mayor 1991). However, a discrepancy with
the absolute magnitude suggests that the two companions could also be distinct,
with the resolved one being the outermost component of a triple system. The
brown dwarf HD 49197B is a new member of a growing list of directly imaged
sub-stellar companions at 10-1000 AU separations from main sequence stars,
indicating that such brown dwarfs may be more common than initially speculated.


title:
The metal enrichment of the intracluster medium in hierarchical galaxy
  formation models

abstract:
  We investigate the metal enrichment of the intracluster medium (ICM) in the
framework of hierarchical models of galaxy formation. We calculate the
formation and evolution of galaxies and clusters using a semi-analytical model
which includes the effects of flows of gas and metals both into and out of
galaxies. For the first time in a semi-analytical model, we calculate the
production of both alpha and iron-peak elements based on theoretical models for
the lifetimes and ejecta of type Ia and type II supernovae (SNe Ia and SNe II).
It is essential to include the long lifetimes of the SNIa progenitors in order
to correctly model the evolution of the iron-peak elements. We find that if all
stars form with an IMF similar to that found in the solar neighbourhood, then
the metallicities of O, Mg, Si and Fe in the ICM are predicted to be 2-3 times
lower than observed values. In contrast, a model (also favoured on other
grounds) in which stars formed in bursts triggered by galaxy mergers have a
top-heavy IMF reproduces the observed ICM abundances of O, Mg, Si and Fe. The
same model predicts ratios of ICM mass to total stellar luminosity in clusters
which agree well with observations. According to our model, the bulk of the
metals in clusters are produced by L* and brighter galaxies. [abridged]


title: A search for circumstellar dust disks with ADONIS

abstract:
  We present results of a coronographic imaging search for circumstellar dust
disks with the Adaptive Optics Near Infrared System (ADONIS) at the ESO 3.6m
telescope in La Silla (Chile). 22 candidate stars, known to be orbited by a
planet or to show infrared excess radiation, were examined for circumstellar
material. In the PSF-subtracted images no clear disk was found. We further
determine the detection sensitivities and outline how remaining atmospheric
fluctuations still can hamper adaptive optics observations.


title:
Detection of 21 Centimeter HI Absorption at z = 0.78 in a Survey of
  Radio Continuum Sources

abstract:
  We report the detection of a deep broad HI 21 cm absorption system at z =
0.78 toward the radio source [HB89] 2351+456 (4C+45.51) at z = 1.992. The HI
absorption was identified in a blind spectral line survey conducted at the
Green Bank Telescope spanning 0.63 < z < 1.10 toward a large sample of radio
continuum sources. The HI column density is N(HI) = 2.35 x 10^19 (T_s/f) cm^-2,
where T_s is the spin temperature and f is the continuum covering factor of the
absorbing gas. For T_s/f > 8.5 K, this system is by definition a damped Ly
alpha absorption system (N(HI) >= 2 x 10^20 cm^-2). The line is unusually
broad, with a FWHM of 53 km/s and a full span of 163 km/s, suggesting a
physically extended HI gas structure. Radio surveys identify damped Ly alpha
systems in a manner that bypasses many of the selection effects present in
optical/UV surveys, including dust extinction and the atmospheric cutoff for z
< 1.65. The smooth broad profile of this HI 21 cm absorption system is similar
to the z = 0.89 HI absorption toward PKS 1830-211, which suggests that the
absorber toward [HB89] 2351+456 is also a gravitational lens and a molecular
absorption system. However, very long baseline interferometry and Hubble Space
Telescope observations show little evidence for gravitational lensing, and BIMA
millimeter observations show no HCO+ (1-2) or HCN (1-2) absorption down to tau
= 0.15 (3 sigma) in 5 km/s channels. Although this radio damped Ly alpha
selection technique would include dusty, molecule-rich systems, [HB89] 2351+456
appears to be a ``vanilla'' HI 21 cm absorber.


title: The massive star IMF at high metallicity

abstract:
  The question of the variation of the upper IMF at high metallicity is briefly
reviewed. I show recent results suggesting a revision in the definition of
`high metallicity' in extragalactic H II regions. I present preliminary results
concerning constraints on the upper mass limit in metal-rich spiral galaxies
derived from the detection of Wolf-Rayet stars in the spectra of their H II
regions.
  The current evidence is in support of an IMF extending up to at least 60-70
solar masses at an oxygen abundance 1-1.5 times the solar value.


title: The Case of the Off-Center, Levitating Bar in the Large Magellanic Cloud

abstract:
  I explore the hypothesis that many of the unusual aspects of the apparent
stellar bar of the Large Magellanic Cloud are the result of viewing a triaxial
stellar bulge that is embedded in a highly obscuring thin disk. Specifically,
this hypothesis explains the observed off-center position of the bar within the
disk, the differing apparent distances of the bar and disk, the near alignment
of the bar's major axis position angle and the disk's line-of-nodes, and the
asymmetric appearance of the bar itself. Indirectly, it may also play a role in
explaining the microlensing rate toward the LMC and the recently observed large
velocity dispersion of RR Lyrae stars.


title: Radio observations of a few giant sources

abstract:
  We present multifrequency observations with the Giant Metrewave Radio
Telescope (GMRT) and the Very Large Array (VLA) of a sample of seventeen
largely giant radio sources (GRSs). These observations have either helped
clarify the radio structures or provided new information at a different
frequency. The broad line radio galaxy, J0313+413, has an asymmetric, curved
radio jet and a variable radio core, consistent with a moderate angle of
inclination to the line of sight. We attempt to identify steep spectrum radio
cores (SSCs), which may be a sign of recurrent activity, and find four
candidates. If confirmed, this would indicate a trend for SSCs to occur
preferentially in GRSs. From the structure and integrated spectra of the
sources we suggest that the lobes of emission in J0139+399 and J0200+408 may be
due to an earlier cycle of nuclear activity. We find that inverse-Compton
losses with the cosmic microwave background radiation dominate over synchrotron
radiative losses in the lobes of all the sources, consistent with earlier
studies. We also show that prominence of the bridge emission decreases with
increasing redshift, possibly due to inverse-Compton losses. This could affect
the appearance and identification of GRSs at large redshifts.


title: The Double-Lined Spectroscopic Binary Haro 1-14c

abstract:
  We report detection of the low-mass secondary in the spectroscopic binary
Haro 1-14c in the Ophiuchus star forming region. The secondary/primary mass
ratio is $0.310\pm 0.014$. With an estimated photometric primary mass of 1.2
$M_{\odot}$, the secondary mass is $\sim 0.4 M_{\odot}$ and the projected
semi-major axis is $\sim 1.5$ AU. The system is well-suited for astrometric
mapping of its orbit with the current generation of ground-based IR
interferometers. This could yield precision values of the system's component
masses and distance.


title: The 2dF Galaxy Redshift Survey: the local E+A galaxy population

abstract:
  We select a sample of low-redshift (z ~ 0.1) E+A galaxies from the 2dF Galaxy
Redshift Survey (2dFGRS). The spectra of these objects are defined by strong
hydrogen Balmer absorption lines (H-delta, H-gamma, H-beta) combined with a
lack of [OII] 3727A emission, together implying a recently-truncated burst of
star formation. The E+A spectrum is thus a signpost to galaxies in the process
of evolution. We quantify the local environments, clustering properties and
luminosity function of the E+A galaxies. We find that the environments are
consistent with the ensemble of 2dFGRS galaxies: low-redshift E+A systems are
located predominantly in the field, existing as isolated objects or in poor
groups. However, the luminosity distribution of galaxies selected using three
Balmer absorption lines H-delta-gamma-beta appears more typical of ellipticals.
Indeed, morphologically these galaxies are preferentially spheroidal (E/S0)
systems. In a small but significant number we find evidence for recent major
mergers, such as tidal tails. We infer that major mergers are one important
formation mechanism for E+A galaxies, as suggested by previous studies. At low
redshift the merger probability is high in the field and low in clusters, thus
these recently-formed spheroidal systems do not follow the usual
morphology-density relation for ellipticals. Regarding the selection of E+A
galaxies: we find that basing the Balmer-line criterion solely on H-delta
absorption leads to a significant sub-population of disk systems with
detectable H-alpha emission. In these objects the [OII] emission is presumably
either obscured by dust or present with a low signal-to-noise ratio, whilst the
(H-gamma, H-beta) absorption features are subject to emission-filling.


title: Submillimeter Observations of Low Metallicity Galaxy NGC 4214

abstract:
  Results of submillimeter (450 micron and 850 micron) observations of a nearby
dwarf irregular galaxy NGC 4214 with SCUBA on JCMT are presented. We aimed at
examining the far-infrared to submillimeter spectral energy distribution (SED)
and properties of dust thermal emission in a low metallicity environment by
choosing NGC 4214 of which gas metallicity (log O/H + 12) is 8.34. We found
that the SED is quite similar to those of IRAS bright galaxies sample (IBGS)
which are local bright star-forming galaxies with metallicity comparable to the
solar abundance. A dust temperature and an emissivity index for NGC 4214
obtained by a fitting to the single temperature greybody model are T_d = 35 \pm
0.8 K and beta = 1.4 \pm 0.1, respectively, which are typical values for IBGS.
Compiling the previous studies on similar nearby dwarf irregular galaxies, we
found that NGC 1569 shows similar results to those of NGC 4214, while NGC 4449
and IC 10 SE show different SEDs and low emissivity indices. There seems to be
a variety of SEDs among metal poor dwarf irregular galaxies. We examined
dependence on intensity of interstellar radiation field as well as
two-temperature model, but the origin of the difference is not clear. Some
mechanism(s) other than metallicity and interstellar radiation field must be
responsible for controlling dust emission property.


title: High Energy Emission from Magnetars

abstract:
  The recently discovered soft gamma-ray emission from the anomalous X-ray
pulsar 1E 1841-045 has a luminosity L_g ~ 10^{36} ergs/s. This luminosity
exceeds the spindown power by three orders of magnitude and must be fed by an
alternative source of energy such as an ultrastrong magnetic field. A gradual
release of energy in the stellar magnetosphere is expected if it is twisted and
a strong electric current is induced on the closed field lines. We examine two
mechanisms of gamma-ray emission associated with the gradual dissipation of
this current. (1) A thin surface layer of the star is heated by the downward
beam of current-carrying charges, which excite Langmuir turbulence in the
layer. As a result, it can reach a temperature kT ~ 100 keV and emit
bremsstrahlung photons up to this characteristic energy. (2) The magnetosphere
is also a source of soft gamma rays at a distance of ~100 km from the star,
where the electron cyclotron energy is in the keV range. A large electric field
develops in this region in response to the outward drag force felt by the
current-carrying electrons from the flux of keV photons leaving the star. A
seed positron injected in this region undergoes a runaway acceleration and
upscatters keV photons above the threshold for pair creation. The created pairs
emit a synchrotron spectrum consistent with the observed 20-100 keV emission.
This spectrum is predicted to extend to higher energies and reach a peak at ~1
MeV.


title:
Protoplanetary Earth Formation: Further Evidence and Geophysical
  Implications

abstract:
  Recently, I showed that the "standard model" of solar system formation is
wrong,yielding the contradiction of terrestrial planets having insufficiently
massive cores, and showed instead the consistency of Eucken's 1944 concept of
planets raining out in the central regions of hot, gaseous protoplanets.
Planets generally consist of concentric shells of matter, but there has been no
adequate geophysical explanation to account for the Earth's non-contiguous
crustal continental rock layer, except by assuming that the Earth in the
distant past was smaller and subsequently expanded. Here, I show that formation
of Earth, from within a Jupiter-like protoplanet, will account for the
compression of the rocky Earth to about 64 percent of its current radius,
yielding a closed, contiguous continental shell with concomitant Earth
expansion commencing upon the subsequent removal of its protoplanetary gaseous
shell. I now propose that Earth expansion progresses, not from spreading at
mid-oceanic ridges as usually assumed, but primarily by the formation of
expansion cracks (often near continental margins) and the in-filling of those
cracks with basalt (produced from volume expansion in the mantle), which is
extruded mainly at mid-oceanic ridges, solidifies and traverses the ocean floor
by gravitational creep to regions of lower gravitational potential energy,
ultimately plunging downward into distant expansion cracks, emulating
subduction. Viewed from that perspective, most of the evidence presented in
support of plate tectonics supports Earth expansion; mantle convection is not
required, and the timescale for Earth expansion is no longer constrained to
about 200 million years, the maximum age of the current ocean floor.


title:
Pulsation of M-type Mira variables with moderately different mass:
  search for observable mass effects

abstract:
  Models of M-type Miras with masses of 1 $M_\odot$ and 1.2 $M_\odot$, i.e.
with envelope masses of about 0.4 $M_\odot$ and 0.6 $M_\odot$, have been
constructed, and a comparison has been made of their observable properties.
Geometric pulsation of continuum-forming layers is found to be little affected
by the mass difference. The influence of molecular contamination of
near-infrared continuum bandpasses upon interferometrically measured fit
diameters ranges from undetectable to quite significant. Some pulsation cycles
of the lower-mass model Mira show substantially stronger contamination than
that found in any cycle of the higher-mass star. Observations which sample
pulsation phase well and continuously are crucial for avoiding
misinterpretations, because the assignment of absolute pulsation phases is
inherently uncertain by at least 0.1 cycles, diameter changes may be strongly
phase-dependent, and cycle-to-cycle variations may be substantial. In accord
with expectations, we find that cycle-to-cycle variations that show up in light
curves and in near-continuum diameters tend to be larger and more common in the
low-mass models, leading to one possible way to discriminate mass. Two other
methods, based on high-precision measurements of the pulsation amplitude and on
derivation of pre-maximum effective temperatures from diameter measurements,
are also discussed. High-layer features that may be strongly affected by mass
are not well described by present dust-free models.


title:
Chandra Observation of a Group of Galaxies HCG 80: Does the Spiral-Only
  Group Have Hot Intragroup Gas?

abstract:
  We present an analysis of Chandra X-ray observations of a compact group of
galaxies, HCG 80 (z=0.03). The system is a spiral-only group composed of four
late-type galaxies, and has a high-velocity dispersion of 309 km/s. With
high-sensitivity Chandra observations, we searched for diffuse X-ray emission
from the intragroup medium (IGM); however, no significant emission was
detected. We place a severe upper limit on the luminosity of the diffuse gas as
LX < 6e40 erg/s. On the other hand, significant emission from three of the four
members were detected. In particular, we discovered huge halo emission from HCG
80a that extends on a scale of ~30 kpc perpendicular to the galactic disk,
whose X-ray temperature and luminosity were measured to be ~0.6 keV and ~4e40
erg/s in the 0.5-2 keV band, respectively. It is most likely to be an outflow
powered by intense starburst activity. Based on the results, we discuss
possible reasons for the absence of diffuse X-ray emission in the HCG 80 group,
suggesting that the system is subject to galaxy interactions, and is possibly
at an early stage of IGM evolution.


title:
Calculation of the dependence of transition frequencies on the fine
  structure constant and the search for variation of alpha in QSO spectra

abstract:
  We calculate the dependence of atomic transition frequencies on the fine
structure constant, $\alpha = e^2/\hbar c$, for some ions of Ti, Mn, Na, C, and
O. The results of these calculations will be used in the search for variation
of alpha in quasar absorption spectra.


title: The metallicity distribution of F/G dwarfs derived from BATC survey data

abstract:
  Based on synthetic flux spectra calculated from theoretical atmospheric
models, a calibration of temperature and metallicity for the dwarfs observed in
the Beijing-Arizona-Taiwan-Connecticut (BATC) multicolor photometric system is
presented in this paper. According to this calibration, stellar effective
temperatures can be obtained from some temperature-sensitive color indices. The
sample stars have colors and magnitudes in the ranges 0.1<d-i<0.9 and
14.0<i<20.5. The photometric metallicities for these sample stars can be
derived by fitting SEDs. We determine the average stellar metallicity as a
function of distance from the Galactic plane. The metallicity gradient is found
to be d[Fe/H]/dz=-0.37+-0.1dex/kpc for z<4 kpc and
d[Fe/H]/dz=-0.06+-0.09dex/kpc between 5 and 15 kpc. These results can be
explained in terms of different contributions in density distribution for
Galactic models `thin disk', `thick disk' and `halo' components. However, for
the gradient in z>5 kpc, it could not be interpreted according to the different
contributions from the three components because of the large uncertainty. So it
is possible that there is little or no gradient for z>5 kpc. The overall
distribution shows a metallicity gradient d[Fe/H]/dz=-0.17+-0.04dex/kpc for
z<15 kpc.


title:
Cumulative analysis of the association between the gravitational wave
  detectors NAUTILUS and EXPLORER and the gamma-ray bursts detected by BATSE
  and BeppoSAX

abstract:
  The statistical association between the output of the Gravitational Wave (GW)
detectors EXPLORER and NAUTILUS and a list of Gamma Ray Bursts (GRBs) detected
by the satellite experiments BATSE and BeppoSAX has been analyzed using
cumulative algorithms. GW detector data collected between 1991 and 1999 have
been correlated to the GRB flux peak times. The cumulative analysis of a large
number of GRBs (387) allows to push the upper bound for the corresponding GW
burst amplitude down to $h = 2.5\cdot10^{-19}$.