title:
Detecting Reflected Light from Close-In Extrasolar Giant Planets with
  the Kepler Photometer

abstract:
  NASA's Kepler Mission promises to detect transiting Earth-sized planets in
the habitable zones of solar-like stars. In addition, it will be poised to
detect the reflected light component from close-in extrasolar giant planets
(CEGPs) similar to 51 Peg b. Here we use the DIARAD/SOHO time series along with
models for the reflected light signatures of CEGPs to evaluate Kepler's ability
to detect such planets. We examine the detectability as a function of stellar
brightness, stellar rotation period, planetary orbital inclination angle, and
planetary orbital period, and then estimate the total number of CEGPs that
Kepler will detect over its four year mission. The analysis shows that
intrinsic stellar variability of solar-like stars is a major obstacle to
detecting the reflected light from CEGPs. Monte Carlo trials are used to
estimate the detection threshold required to limit the total number of expected
false alarms to no more than one for a survey of 100,000 stellar light curves.
Kepler will likely detect 100-760 51 Peg b-like planets by reflected light with
orbital periods up to 7 days.


title: Cosmology with the Ly-a forest

abstract:
  The Lya forest has emerged as one of the few systems capable of probing
small-scale structure at high-z with high precision. In this talk I highlight
two areas in which the Lya forest is shedding light on fundamental questions in
cosmology, one speculative and one which should be possible in the near future.


title: Quantifying the Bull's Eye Effect

abstract:
  We have used N-body simulations to develop two independent methods to
quantify redshift distortions known as the Bull's Eye effect (large scale
infall plus small scale virial motion). This effect depends upon the mass
density, $\Omega_0$, so measuring it can in principle give an estimate of this
important cosmological parameter. We are able to measure the effect and
distinguish between its strength for high and low values of $\Omega_0$. Unlike
other techniques which utilize redshift distortions, one of our methods is
relatively insensitive to bias. In one approach, we use path lengths between
contour crossings of the density field. The other is based upon percolation. We
have found both methods to be successful in quantifying the effect and
distinguishing between values of $\Omega_0$. However, only the path lengths
method exhibits low sensitivity to bias.


title: Old and Young X-ray Point Source Populations in Nearby Galaxies

abstract:
  We analyzed 1441 Chandra X-ray point sources in 32 nearby galaxies. The total
point-source X-ray luminosity L_XP is well correlated with B, K, and FIR+UV
luminosities of spiral host galaxies, and with the B and K luminosities for
ellipticals. This suggests an intimate connection between L_XP and both the old
and young stellar populations, for which K and FIR+UV luminosities are proxies
for the galaxy mass M and star-formation rate SFR. We derive proportionality
constants 1.3E29 erg/s/Msol and 0.7E39 erg/s/(Msol/yr), which can be used to
estimate the old and young components from M and SFR, respectively. The
cumulative X-ray luminosity functions for the point sources have quite
different slopes for the spirals (gamma ~= 0.5-0.8) and ellipticals (gamma ~=
1.4), implying *the most luminous point sources dominate L_XP* for the spirals.
Most of the point sources have X-ray colors that are consistent with either
LMXBs or Ultraluminous X-ray sources (ULXs a.k.a. IXOs) and we rule out
classical HMXBs (e.g. neutron-star X-ray pulsars) as contributing much to L_XP.
Thus, for spirals, the ULXs dominate L_XP. We estimate that >~20% of all ULXs
found in spirals originate from the older (pop II) stellar populations,
indicating that many of the ULXs that have been found in spiral galaxies are in
fact pop II ULXs, like those in elliptical galaxies. The linear dependence of
L_XP on the SFR argues for either a steepening in the X-ray luminosity function
of the young (pop I) X-ray source population at L_X >~10^(38.5-39) erg/s, or a
decreasing efficiency for producing all types of young X-ray point sources as
the galaxy SFR increases.


title:
Natural Coronagraphic Observations of the Eclipsing T Tauri System KH
  15D: Evidence for Accretion and Bipolar Outflow in a WTTS

abstract:
  We present high resolution (R $\sim$ 44,000) UVES spectra of the eclipsing
pre-main sequence star KH 15D covering the wavelength range 4780 to 6810 {\AA}
obtained at three phases: out of eclipse, near minimum light and during egress.
The system evidently acts like a natural coronagraph, enhancing the contrast
relative to the continuum of hydrogen and forbidden emission lines during
eclipse. At maximum light the H$\alpha$ equivalent width was $\sim$2 {\AA} and
the profile showed broad wings and a deep central absorption. During egress the
equivalent width was much higher ($\sim$70 {\AA}) and the broad wings, which
extend to $\pm$ 300 km/s, were prominent. During eclipse totality the
equivalent width was less than during egress ($\sim$40 {\AA}) and the high
velocity wings were much weaker. H$\beta$ showed a somewhat different behavior,
revealing only the blue-shifted portion of the high velocity component during
eclipse and egress. [OI] $\lambda\lambda$6300, 6363 lines are easily seen both
out of eclipse and when the photosphere is obscured and exhibit little or no
flux variation with eclipse phase. Our interpretation is that KH 15D, although
clearly a weak-line T Tauri star by the usual criteria, is still accreting
matter from a circumstellar disk, and has a well-collimated bipolar jet. As the
knife-edge of the occulting matter passes across the close stellar environment
it is evidently revealing structure in the magnetosphere of this pre-main
sequence star with unprecedented spatial resolution. We also show that there is
only a small, perhaps marginally significant, change in the velocity of the K7
star between the maximum light and egress phases probed here.


title: An analytic model of rotating hot spot and kHz QPOs in X-ray binaries

abstract:
  An analytic model of rotating hot spot is proposed to explain kilohertz
quasi-periodic oscillations (kHz QPO) in X-ray binaries, which is based on the
magnetic coupling (MC) of a rotating black hole (BH) with its surrounding
accretion disc. The hot spot in the inner region of the disc is produced by
energy transferred from a spinning BH with non-axisymmetric magnetic field. The
frequency and energy band of the hot spot turns out to be related to six
parameters, by which the strength and the azimuthal angular region of the
bulging magnetic field on the BH horizon, the mass and spin of the BH, and the
power-law index of the magnetic field varying with the radial coordinate on the
disc are described. In addition, the correlation of the fluctuation of the
bulging magnetic field with the widths of QPO frequency is discussed.


title: A New Population of Old Stars

abstract:
  We report the results of a coherent study of three chemically anomalous
metal-poor ([Fe/H] ~ -2) stars. These objects exhibit unusually low abundances
of Mg, Si, Ca (alpha-elements) and Sr, Y, and Ba (neutron-capture elements).
Our analyses confirm and expand upon earlier reports of atypical abundances in
BD+80~245, G4-36, and CS22966-043. We also find that the latter two stars
exhibit enhanced abundances of Cr, Mn, Ni, and Zn (iron-peak elements), along
with what appears to be large abundances of Ga, with respect to the abundance
of iron. Comparing the chemical abundances of these stars to supernova model
yields, we derive supernovae ratios of Type Ia versus Type II events in the
range of 0.6 <= (N_Ia/N_II) <= 1.3. Whereas, for the Sun, we derive supernovae
ratios in good agreement with those found in the literature: 0.18 +/- 0.01 <
(N_Ia/N_II)_sun < 0.25 +/- 0.06. Given the relatively low metallicity and high
(N_Ia/N_II) ratios of the low-alpha stars studied here, these objects may have
witnessed, or been born from material produced in the yields of the earliest
supernova Type Ia events.


title: The structure and evolution of M51-type galaxies

abstract:
  We discuss the integrated kinematic parameters of 20 M51-type binary
galaxies. A comparison of the orbital masses of the galaxies with the sum of
the individual masses suggests that moderately massive dark halos surround
bright spiral galaxies. The relative velocities of the galaxies in binary
systems were found to decrease with increasing relative luminosity of the
satellite. We obtained evidence that the Tully-Fisher relation for binary
members could be flatter than that for local field galaxies. An enhanced star
formation rate in the binary members may be responsible for this effect. In
most binary systems, the direction of orbital motion of the satellite coincides
with the direction of rotation of the main galaxy. Seven candidates for distant
M51-type objects were found in the Northern and Southern Hubble Deep Fields. A
comparison of this number with the statistics of nearby galaxies provides
evidence for the rapid evolution of the space density of M51-type galaxies with
redshift Z. We assume that M51-type binary systems could be formed through the
capture of a satellite by a massive spiral galaxy. It is also possible that the
main galaxy and its satellite in some of the systems have a common cosmological
origin.


title:
Correlation between the Mean Matter Density and the Width of the
  Saturated Lyman Alpha Absorption

abstract:
  We report a scaling of the mean matter density with the width of the
saturated Lyman alpha absorptions. This property is established using the
``pseudo-hydro'' technique (Croft et al. 1998). It provides a constraint for
the inversion of the Lyman alpha forest, which encounters difficulty in the
saturated region. With a Gaussian density profile and the scaling relation, a
simple inversion of the simulated Lyman alpha forests shows that the
one-dimensional mass power spectrum is well recovered on scales above 2 Mpc/h,
or roughly k < 0.03 s/km, at z=3. The recovery underestimates the power on
small scales, but improvement is possible with a more sophisticated algorithm.


title:
A reduced transfer equation in one-dimensional spherical geometry with
  central symmetry

abstract:
  The transfer equation in spherical geometry with central symmetry, which is a
partial differential equation in two variables r and m, is reduced to a
one-dimensional transfer equation in r parametric in m. This is done by
dropping the angular derivative from the equation in conservation form without
impeding the moments of the specific intensity. The justification for this
reduction of the transfer equation is demonstrated analytically and
numerically. The numerical demonstration is made by comparing the moments,
zeroth to fourth, obtained using the analytic solutions in r of both the
reduced equation and the transfer equation in conservation form using the
discrete ordinates method. The agreement between the two sets of data is
perfect within round-off errors.


title: The Bulk Motion of Flat Edge-On Galaxies Based on 2MASS Photometry

abstract:
  We report the results of applying the 2MASS Tully-Fisher (TF) relations to
study the galaxy bulk flows. For 1141 all-sky distributed flat RFGC galaxies we
construct J, H, K_s TF relations and find that Kron $J_{fe}$ magnitudes show
the smallest dispersion on the TF diagram. For the sample of 971 RFGC galaxies
with V_{3K} < 18000 km/s we find a dispersion $\sigma_{TF}=0.42^m$ and an
amplitude of bulk flow V= 199 +/-61 km/s, directed towards l=301 degr +/-18
degr, b=-2 degr +/-15 degr. Our determination of low-amplitude coherent flow is
in good agreement with a set of recent data derived from EFAR, PSCz, SCI/SCII
samples. The resultant two- dimensional smoothed peculiar velocity field traces
well the large-scale density variations in the galaxy distributions. The
regions of large positive peculiar velocities lie in the direction of the Great
Attractor and Shapley concentration. A significant negative peculiar velocity
is seen in the direction of Bootes and in the direction of the Local void. A
small positive peculiar velocity (100 -- 150 km/s) is seen towards the
Pisces-Perseus supercluster, as well as the Hercules - Coma - Corona Borealis
supercluster regions.


title:
Multiplicity of Nearby Free-floating Ultra-cool Dwarfs: a HST-WFPC2
  search for companions

abstract:
  We present HST/WFPC2 observations of a sample of 134 ultra-cool objects
(spectral types later than M7) coming from the DENIS, 2MASS and SDSS surveys,
with distances estimated to range from 7 pc to 105 pc. Fifteen new ultra-cool
binary candidates are reported here. Eleven known binaries are confirmed and
orbital motion is detected in some of them. We estimate that the closest binary
systems in this sample have periods between 5 and 20 years, and thus dynamical
masses will be derived in the near future. For the calculation of binary
frequency we restrict ourselves to systems with distances less than 20 pc.
After correction of the binaries bias, we find a ratio of visual binaries (at
the HST limit of detection) of around 10%, and that ~15% of the 26 objects
within 20 parsecs are binary systems with separations between 1 and 8 A.U. The
observed frequency of ultra-cool binaries is similar than that of binaries with
G-type primaries in the separation range from 2.1 A.U. to 140 A.U. There is
also a clear deficit of ultra-cool binaries with separations greater than 15
A.U., and a possible tendency for the binaries to have mass ratios near unity.
Most systems have indeed visual and near-infrared brightness ratios between 1
and 0.3. We discuss our results in the framework of current scenarios for the
formation and evolution of free-floating brown dwarfs.


title: Observing the CMB at High-l using the VSA and AMI

abstract:
  We discuss two experiments - the Very Small Array (VSA) and the Arcminute
MicroKelvin Imager (AMI) - and their prospects for observing the CMB at high
angular multipoles. Whilst the VSA is primarily designed to observe primary
anisotropies in the CMB, AMI is designed to image secondary anisotropies via
the Sunyaev-Zel'dovich effect. The combined l-range of these two instruments is
between l = 150 and ~10000.


title: Transition from collisionless to collisional MRI

abstract:
  Recent calculations by Quataert et al. (2002) found that the growth rates of
the magnetorotational instability (MRI) in a collisionless plasma can differ
significantly from those calculated using MHD. This can be important in hot
accretion flows around compact objects. In this paper we study the transition
from the collisionless kinetic regime to the collisional MHD regime, mapping
out the dependence of the MRI growth rate on collisionality. A kinetic closure
scheme for a magnetized plasma is used that includes the effect of collisions
via a BGK operator. The transition to MHD occurs as the mean free path becomes
short compared to the parallel wavelength $2\pi/k_{\Par}$. In the weak magnetic
field regime where the Alfv\'en and MRI frequencies $\omega$ are small compared
to the sound wave frequency $k_{\Par} c_0$, the dynamics are still effectively
collisionless even if $\omega \ll \nu$, so long as the collision frequency $\nu
\ll k_{\Par} c_{0}$; for an accretion flow this requires $\nu \lsim \Omega
\sqrt{\beta}$. The low collisionality regime not only modifies the MRI growth
rate, but also introduces collisionless Landau or Barnes damping of long
wavelength modes, which may be important for the nonlinear saturation of the
MRI.


title: The Local Interstellar Spectrum of Cosmic Ray Electrons

abstract:
  The local interstellar spectrum of cosmic ray electrons and positrons from
0.8 GeV to 2 TeV is derived by demodulating the measured spectra by balloon and
satellite experiments. It can be well represented by a single power law in
kinetic energy with spectral index 3.4 over the whole energy range, pushing for
the idea that it is not representative of the galactic average. Instead, the
spectrum has to reflect the nature of our local bubble, being mostly sensitive
to the last nearby supernova.


title: Chandra observations of NGC4698: a Seyfert-2 with no absorption

abstract:
  We present Chandra ACIS-S observations of the enigmatic
  Seyfert-2 galaxy NGC4698. This object together with several other bona-fide
Seyfert-2 galaxies show no absorption in the low spatial resolution ASCA data,
in contrast to the standard unification models. Our Chandra observations of
NGC4698 probe directly the nucleus allowing us to check whether nearby sources
contaminate the ASCA spectrum. Indeed, the Chandra observations show that the
  ASCA spectrum is dominated by two nearby AGN. The X-ray flux of NGC4698 is
dominated by a nuclear source with luminosity L(0.3-8 keV) ~ 10^39, erg s-1
coincident with the radio nucleus. Its spectrum is well represented by a
power-law, ~ 2.2, obscured by a small column density of 5x10^20 cm-2 suggesting
that NGC4698 is an atypical Seyfert galaxy.
  On the basis of its low luminosity we then interpret NGC4698 as a Seyfert
galaxy which lacks a broad-line region.


title:
XMM-Newton study of the persistent X-ray source 1E1743.1-2843 located in
  the Galactic Center direction

abstract:
  We report the results of an XMM-Newton observation of the persistent X-ray
source 1E1743.1-2843, located in the Galactic Center (GC) direction. We
determine the position of the source at alpha_J2000=17h46m21.0s,
delta_J2000=-28deg43'44" (with an uncertainty of 1.5"), which is the most
accurate to date, and will enable cross-identifications at other wavelengths.
The source was bright during this observation (L_2-10keV ~ 2.7 x 10^36
d^2_10kpc erg/s for a power-law continuum), with no significant variability. We
propose that 1E1743.1-2843 may be explained in terms of a black hole candidate
in a low/hard state. There is an indication that the source exhibits different
states from a comparison of our results with previous observations (e.g.,
ART-P, BeppoSAX). However, the present spectral analysis does not rule out the
hypothesis of a neutron star low-mass X-ray binary as suggested previously. If
1E1743.1-2843 is actually located in the GC region, we might expect to observe
significant 6.4keV fluorescent iron line emission from nearby molecular clouds
(e.g., GCM+0.25+0.01).


title:
Effects of the background radiation on radio pulsar and supernova
  remnant searches and the birth rates of these objects

abstract:
  In different directions of the Galaxy the Galactic background radio radiation
and radiation of complex star formation regions which include large number of
OB associations have different influences on radio pulsar (PSR) and supernova
remnant (SNR) searches. In this work we analyse the effects of these background
radiations on the observations of PSRs at 1400 MHz and SNRs at 1000 MHz. In the
interval l=0$^o$$\pm60^o$ the PSRs with flux F$_{1400}$$>$0.2 mJy and the SNRs
with surface brightness $\Sigma$$>10^{-21}$ Wm$^{-2}$Hz$^{-1}$sr$^{-1}$ are
observable for all values of l and b. All the SNRs with
$\Sigma$$>3\times10^{-22}$ Wm$^{-2}$Hz$^{-1}$sr$^{-1}$ can be observed in the
interval 60$^o$$<$l$<300^o$. We have examined samples of PSRs and SNRs to
estimate the birth rates of these objects in the region up to 3.2 kpc from the
Sun and also in the Galaxy. The birth rate of PSRs is about one in 200 years
and the birth rate of SNRs is about one in 65 years in our galaxy.


title: The s-Process in Rotating Asymptotic Giant Branch Stars

abstract:
  (abridged) We model the nucleosynthesis during the thermal pulse phase of a
rotating, solar metallicity AGB star of 3M_sun. Rotationally induced mixing
during the thermal pulses produces a layer (~2E-5M_sun) on top of the CO-core
where large amounts of protons and C12 co-exist. We follow the abundance
evolution in this layer, in particular that of the neutron source C13 and of
the neutron poison N14. In our AGB model mixing persists during the entire
interpulse phase due to the steep angular velocity gradient at the
core-envelope interface. We follow the neutron production during the interpulse
phase, and find a resulting maximum neutron exposure of tau_max =0.04 mbarn^-1,
which is too small to produce any significant s-process. In parametric models,
we then investigate the combined effects of diffusive overshooting from the
convective envelope and rotationally induced mixing. Models with overshoot and
weaker interpulse mixing - as perhaps expected from more slowly rotating stars
- yield larger neutron exposures. We conclude that the incorporation of
rotationally induce mixing processes has important consequences for the
production of heavy elements in AGB stars. Through a distribution of initial
rotation rates it may lead to a natural spread in the neutron exposures
obtained in AGB stars of a given mass - as appears to be required by
observations. Our results suggest that both processes, diffusive overshoot and
rotational mixing, may be required to obtain a consistent description of the
s-process in AGB stars which fulfils all observational constraints. Finally, we
find that mixing due to rotation within our current framework does increase the
production of N15 in the partial mixing zone, however still falling short of
what seems required by observations.


title: The First Data Release of the Sloan Digital Sky Survey

abstract:
  The Sloan Digital Sky Survey has validated and made publicly available its
First Data Release. This consists of 2099 square degrees of five-band (u, g, r,
i, z) imaging data, 186,240 spectra of galaxies, quasars, stars and calibrating
blank sky patches selected over 1360 square degrees of this area, and tables of
measured parameters from these data. The imaging data go to a depth of r ~ 22.6
and are photometrically and astrometrically calibrated to 2% rms and 100
milli-arcsec rms per coordinate, respectively. The spectra cover the range
3800--9200 A, with a resolution of 1800--2100. Further characteristics of the
data are described, as are the data products themselves.


title: Revised Rates of Stellar Disruption in Galactic Nuclei

abstract:
  We compute rates of tidal disruption of stars by supermassive black holes in
galactic nuclei, using downwardly-revised black hole masses from the M-sigma
relation. In galaxies with steep nuclear density profiles, which dominate the
overall event rate, the disruption frequency varies inversely with assumed
black hole mass. We compute a total rate for non-dwarf galaxies that is about a
factor ten higher than in earlier studies. Disruption rates are predicted to be
highest in nucleated dwarf galaxies, assuming that such galaxies contain black
holes. Monitoring of a rich galaxy cluster for a few years could rule out the
existence of intermediate mass black holes in dwarf galaxies.


title:
The Abundance Evolution of Oxygen, Sodium and Magnesium in Extremely
  Metal-Poor Intermediate Mass Stars: Implications for the Self-Polution
  Scenario in Globular Clusters

abstract:
  We present full stellar evolution and parametric models of the surface
abundance evolution of O16, Ne22, Na23 and the magnesium isotopes in an
extremely metal-poor intermediate mass star M_ZAMS=5M_sun, Z=0.0001. O16 and
Ne22 are injected into the envelope by the third dredge-up following thermal
pulses on the asymptotic giant branch. These species and the initially present
Mg24 are depleted by hot bottom burning (HBB) during the interpulse phase. As a
result, Na23, Mg25 and Mg26 are enhanced. If the HBB temperatures are
sufficiently high for this process to deplete oxygen efficiently, Na23 is first
produced and then depleted during the interpulse phase. Although the
simultaneous depletion of O16 and enhancement of Na23 is possible, the required
fine tuning of the dredge-up and HBB casts some doubt on the robustness of this
process as the origin of the O-Na anti-correlation observed in globular cluster
stars. However, a very robust prediction of our models are low Mg24/Mg25 and
Mg24/Mg26 ratios whenever significant O16 depletion can be achieved. This seems
to be in stark contrast with recent observations of the magnesium isotopic
ratios in the globular cluster NGC6752.


title: Cosmic Degeneracy with Dark Energy Equation of State

abstract:
  We discuss a degeneracy between the geometry of the universe and the dark
energy equation of state $w_{\rm X}$ which exists in the power spectrum of the
cosmic microwave background. In particular, for the case with $w_{\rm X} < -1$,
this degeneracy has interesting implications to a lower bound on $w_{\rm X}$
from observations. It is also discussed how this degeneracy can be removed
using current observations of type Ia supernovae.


title: Unstable Cold Dark Matter and the Cuspy Halo Problem in Dwarf Galaxies

abstract:
  We speculate that the dark halos of dwarf galaxies and low surface brightness
galaxies soften their central cusps by the decay of a fraction of cold dark
matter (CDM) particles to a stable particle with a recoiling velocity of a few
tens km s$^{-1}$, after they have driven the formation of galactic halos. This
process, however, does not necessarily produce a significant reduction of the
central dark matter density of satellite dwarf spheroidals like Draco or
Fornax. It is shown that the recovered distribution of concentration parameters
$c$ for the initial (before decay) Navarro-Frenk-White halos, is in good
agreement with CDM predictions. Other interesting potentials of unstable CDM
are highlighted.


title:
Chandra Detection of the X-ray counterpart of the High-magnetic field
  Radio Pulsar J1119-6127 in the Supernova Remnant G292.2-0.5

abstract:
  We report the Chandra Advanced CCD Imaging Spectrometer detection of the
X-ray counterpart of the high magnetic field, ~1600 year-old, 407 ms radio
pulsar J1119-6127 associated with the supernova remnant G292.2-0.5. The
powerful imaging capability of Chandra also unveiled, for the first time, a
faint 3"x6" pulsar wind nebula (PWN) at energies above ~1.2 keV. The X-ray
emission from the pulsar and its associated nebula is well described by an
absorbed power law model with a photon index of 2.2 (1.9-2.8). The
corresponding 0.5-10 keV unabsorbed X-ray luminosity is 5.5(2.2-15.5)x10^32
ergs/s (at 6 kpc). When compared to two other pulsars with similar spin and
magnetic properties, J1119-6127 stands out as being the least efficient at
turning rotational kinetic energy into X-ray emission. This study shows that
high magnetic field radio pulsars can be significant X-ray emitters and Chandra
is needed to study the emission properties of the pulsars and associated faint
PWNe.


title:
Beyond Lyman-alpha: Constraints and Consistency Tests from the
  Lyman-beta Forest

abstract:
  Absorption between the rest-frame wavelengths of 973 and 1026 Angstroms in
quasar spectra arises from two sources (apart from occasional metals): one is
due to Lyman-alpha (Lya) absorption by materials at a low redshift, and the
other from Lyman-beta (Lyb) at a higher redshift. These two sources of
absorption are to a good approximation uncorrelated because of their wide
physical separation. Therefore, the two-point correlation of absorption in this
region of quasar spectra neatly factorizes into two pieces: the Lyb correlation
at high z, and the Lya correlation at low z. The latter can be independently
measured from quasar spectra at lower redshifts using current techniques. A
simple division then offers a way to statistically separate out the Lyb
two-point correlation from the Lya correlation. Several applications of this
technique are discussed. First, since the Lyb absorption cross-section is lower
than Lya by about a factor of 5, the Lyb forest is a better probe of the
intergalactic medium (IGM) at higher redshifts where Lya absorption is often
saturated. Second, for the same reason, the Lyb forest allows a better
measurement of the equation of state of the IGM at higher overdensities,
yielding stronger constraints on its slope when used in conjunction with the
Lya forest. Third, models of the Lya forest based on gravitational instability
make unique predictions for the Lyb forest, which can be tested against
observations. We briefly point out that feedback processes that affect higher
density regions but leave low density structure intact may be better
constrained by the Lyb forest.


title: Discovery of Bright Variable X-ray Sources in NGC 1569 with Chandra

abstract:
  From the analysis of a ~100 ks Chandra observation of the dwarf starburst
galaxy NGC 1569, we have found that the X-ray point sources, CXOU
043048.1+645050 and CXOU 043048.6+645058, showed significant time variability.
During this observation, the X-ray flux of CXOU 043048.1+645050 increased by 10
times in only 2 x 10^4 s. Since the spectrum in its bright phase was fitted
with a disk blackbody model with kT_in ~0.43 keV and the bolometric luminosity
is L_bol ~10^38 ergs s^-1, this source is an X-ray binary with a stellar mass
black-hole. Since the spectrum in its faint phase was also fitted with a disk
blackbody model, the time variability can be explained by a change of the
accretion rate onto the black hole. The other variable source, CXOU
043048.6+645058, had a flat spectrum with a photon index of ~1.6. This source
may be an X-ray binary with an X-ray luminosity of several x 10^37 ergs s^-1.
In addition, three other weak sources showed possible time variability. Taking
all of the variability into account may suggest an abundant population of
compact X-ray sources in NGC 1569.


title:
The Stability of the Orbits of Earth-mass Planets in and near the
  Habitable Zones of Known Exoplanetary Systems

abstract:
  We have shown that Earth-mass planets could survive in variously restricted
regions of the habitable zones (HZs) of most of a sample of nine of the 93
main-sequence exoplanetary systems confirmed by May 2003. In a preliminary
extrapolation of our results to the other systems, we estimate that roughly a
third of the 93 systems might be able to have Earth-mass planets in stable,
confined orbits somewhere in their HZs. Clearly, these systems should be high
on the target list for exploration for terrestrial planets. We have reached
this conclusion by launching putative Earth-mass planets in various orbits and
following their fate with a mixed-variable symplectic integrator.


title: Young stars and their circumstellar disks in the Sigma Orionis cluster

abstract:
  The sigma Orionis cluster is a young association evolving under the
disruptive influence of its massive O-star namesake. We are analysing this
cluster as part of a program to characterise the influence of O-stars on the
early stages of stellar evolution. At an age of approximately 4 Myr, this
cluster is at a crucial stage in terms of disk evolution and therefore it is a
key case to better constrain disk dissipation timescales. We have obtained RI
photometry and optical spectroscopy of the sigma Ori cluster; we have analysed
the Li I and Na I features to establish cluster membership. We have thus
gathered a unique sample of spectroscopically confirmed low-mass cluster
members and brown dwarfs. Disk frequencies from K-band excesses from 2MASS
suggest that less than 7% of the very low-mass sigma Ori members have disks, in
stark contrast with even younger clusters (e.g. Trapezium). However,
near-infrared disk frequencies have to be taken with caution. We are currently
undertaking an L-band (imaging) and mid-infrared (imaging and spectroscopy)
program to identify and probe the properties of circumstellar disks around
young stars in this cluster. Preliminary results indicate that at least 30% of
cluster members have circumstellar disks.


title: Discovery of a dust cloud next to sigma Orionis

abstract:
  We report on the discovery of a mid-infrared source at a projected distance
of only 1200 AU from the O9.5 V star sigma Orionis. The spatially resolved,
fan-shaped morphology and the presence of an ionization front, as well as
evidence in the spectrum for processed dust grains, all suggest that it is a
proto-planetary disk being dispersed by the intense ultraviolet radiation from
sigma Orionis. We compute the mass budget and the photo-evaporation timescale,
and discuss the possible nature of this remarkable object.


title: Superlong Gamma-Ray Bursts

abstract:
  Before the BATSE/GRO launch GRBs seem to be a uniform phenomenon with
duration up to about 100 seconds. The BATSE has detected many events longer
than 100 s and a few longer than 500s. We performed the off-line scan of the
1024 ms continuous BATSE records and revealed several non-triggered episodes of
the BATSE GRB triggers which confidently belong to the same GRBs. There are
also several pairs of bursts which are candidates to single very long
(''superlong'') GRBs lasting up to 2000s. Their emission on 500-2000s is prompt
emission rather than afterglow. These superlong GRBs probably belong to the
class of ''long'' GRBs constituting the tail of their duration distribution.
The existence of such events can constrain some models and should be taken into
account in the studies of hard X-ray afterglows.


title:
A molecular line survey of the candidate massive Class 0 prototostar
  IRAS 23385+6053

abstract:
  We have carried out a molecular line survey of the candidate massive
protostar IRAS 23385+6053, covering a 27.2 GHz frequency range in the 330--360
GHz atmospheric window. We detected 27 lines originating from a total of 11
species.Over a third of the identified molecular lines are from the asymmetric
top molecule methanol (CH$_{3}$OH). We did not detect any emission from
high-excitation lines or typical hot core tracers (e.g. CH$_{3}$CN,
HCOOCH$_{3}$). We derive a rotation temperature and column density from the
methanol emission and estimate lower limits to the beam-averaged column density
of the remaining lines. Upper limits to the beam-averaged column density of
selected species were determined from the non-detection of their rotation
lines. We rule out the presence of a hot molecular core associated with IRAS
23385+6053 by a combination of the non-detection of CH$_{3}$CN emission and a
simple bolometric luminosity approach. The molecular inventory and chemistry of
IRAS 23385+6053 are contrasted to that of more evolved massive star-forming
regions and the abundances predicted by recent time-dependent chemical models.
The physical and chemical nature of IRAS 23385+6053 is shown to be consistent
with that immediately prior to the hot molecular core stage.


title:
A Hard Medium Survey with ASCA. IV: the Radio-Loud Type 2 QSO
  AXJ0843+294 2

abstract:
  We discuss the X-ray, optical and radio properties of AX J0843+2942, a high
luminosity Type 2 AGN found in the ASCA Hard Serendipitous Survey. The X-ray
spectrum is best described by an absorbed power-law model with photon index of
Gamma = 1.72 (+0.3 -0.6) and intrinsic absorbing column density of NH = 1.44
(+0.33 -0.52) x 10E23 cm-2. The intrinsic luminosity in the 0.5-10 keV energy
band is ~ 3x10E45 erg s-1, well within the range of quasar luminosities. AX
J0843+2942, positionally coincident with the core of a triple and strong (S_1.4
GHz ~ 1 Jy; P_1.4 GHz ~ 9 x 10E33 erg s-1 Hz-1) radio source, is
spectroscopically identified with a Narrow Line object (intrinsic FWHM of all
the permitted emission lines <= 1200 km s-1) at z=0.398, having line features
and ratios typical of Seyfert-2 like objects. The high X-ray luminosity,
coupled with the high intrinsic absorption, the optical spectral properties and
the radio power, allow us to propose AX J0843+2942 as a Radio-Loud "Type 2
QSO". A discussion of the SED of this object is presented here together with a
comparison with the SED of Ultra Luminous Infrared Galaxies, other "Type 2 QSO"
candidates from the literature, and "normal" Radio-Quiet and Radio-Loud QSOs.


title:
Variable stars as tracers of stellar populations in Local Group
  galaxies: Leo I and NGC 6822

abstract:
  Results are presented of a study of the variable star populations in the
dwarf spheroidal galaxy Leo I and in the dwarf irregular galaxy NGC 6822, based
on time series photometry obtained with the Wide Field Imager of the 2.2 m
ESO/MPI telescope (Leo I) and the Very Large Telescope (NGC 6822). We found
about 250 (lower limit) variables in Leo I most of which are RR Lyrae stars. In
NGC 6822 we identified 450 candidate variables among which about 20 are RR
Lyrae stars, and many are low-luminosity, small-amplitude Cepheids.


title:
The energy spectrum of tau leptons induced by the high energy
  Earth-skimming neutrinos

abstract:
  We present a semi-analytic calculation of the tau-lepton flux emerging from
the Earth, induced by the incident high energy neutrinos interacting inside the
Earth for $10^{5} \leq E_{\nu}/{\rm GeV} \leq 10^{10}$. We obtain results for
the energy dependence of the tau-lepton flux coming from the Earth-skimming
neutrinos, because of the neutrino-nucleon charged-current scattering as well
as the resonant $\bar{\nu}_e e^-$ scattering. We illustrate our results for
several anticipated high energy astrophysical neutrino sources such as the
AGNs, the GRBs, and the GZK neutrino fluxes. The tau lepton fluxes resulting
from rock-skimming and ocean-skimming neutrinos are compared. Such comparisons
can render useful information for the spectral indices of incident neutrino
fluxes.


title: Molecular gas in the central regions of the latest-type spiral galaxies

abstract:
  Using the IRAM 30m telescope, we have surveyed an unbiased sample of 47
nearby spiral galaxies of very late (Scd-Sm) Hubble-type for emission in the
CO(1-0) and CO(2-1) lines. The sensitivity of our data (a few mK) allows
detection of about 60% of our sample in at least one of the CO lines. The
median detected H2 mass is $1.4\times 10^7 \msun$ within the central few kpc,
assuming a standard conversion factor. We use the measured line intensities to
complement existing studies of the molecular gas content of spiral galaxies as
a function of Hubble-type and to significantly improve the statistical
significance of such studies at the late end of the spiral sequence. We find
that the latest-type spirals closely follow the correlation between molecular
gas content and galaxy luminosity established for earlier Hubble types. The
molecular gas in late-type galaxies seems to be less centrally concentrated
than in earlier types. We use Hubble Space Telescope optical images to
correlate the molecular gas mass to the properties of the central galaxy disk
and the compact star cluster that occupies the nucleus of most late-type
spirals. There is no clear correlation between the luminosity of the nuclear
star cluster and the molecular gas mass, although the CO detection rate is
highest for the brightest clusters. It appears that the central surface
brightness of the stellar disk is an important parameter for the amount of
molecular gas at the galaxy center. Whether stellar bars play a critical role
for the gas dynamics remains unclear, in part because of uncertainties in the
morphological classifications of our sample.


title: High Accretion Rate during Class 0 Phase due to External Trigger

abstract:
  Recent observations indicate that some class 0 sources have orders of
magnitude higher accretion rates than those of class I. We investigated the
conditions for the high accretion rates of some class 0 sources by numerical
calculations, modelling an external trigger. For no external trigger, we find
that the maximum value of the accretion rate is determined by the ratio
$\alpha$ of the gravitational energy to the thermal one within a flat inner
region of the cloud core. The accretion rate reaches $\sim 10^{-4} M_{\sun}
yr^{-1}$ if the cloud core has $ \alpha > 2$. For an external trigger we find
that the maximum value of the accretion rate is proportional to the momentum
given to the cloud core. The accretion rate reaches $ > 10^{-4} M_{\sun}
yr^{-1}$ with a momentum of $\sim 0.1 M_{\sun} km s^{-1}$ when the initial
central density of the cloud core is $\sim 10^{-18} g cm^{-3}$. A comparison
between recent observational results for prestellar cores and our no triggered
collapse model indicates that the flat inner regions of typical prestellar
cores are not large enough to cause accretion rates of $\sim 10^{-4} M_{\sun}
yr^{-1}$. Our results show that the triggered collapse of the cloud core is
more preferable for the origin of the high accretion rates of class 0 sources
than no triggered collapse.


title: The Variable Jet of the Vela Pulsar

abstract:
  Observations of the Vela pulsar-wind nebula (PWN) with the Chandra X-ray
Observatory have revealed a complex, variable PWN structure, including inner
and outer arcs, a jet in the direction of the pulsar's proper motion, and a
counter-jet in the opposite direction, embedded in diffuse nebular emission.
  From the analysis of thirteen Chandra observations spread over about 2.5
years we found that this outer jet shows particularly strong variability,
changing its shape and brightness. We observed bright blobs in the outer jet
moving away from the pulsar with apparent speeds (0.3-0.6)c and fading on
time-scales of days to weeks. The spectrum of the outer jet fits a power-law
model with a photon index of 1.3. The X-ray emission of the outer jet can be
interpreted as synchrotron radiation of ultrarelativistic electrons/positrons.
This interpretation allows one to estimate the magnetic field, ~100 microGauss,
maximum energy of X-ray emitting electrons, $2 \times 10^{14}$ eV, and energy
injection rate, $8\times 10^{33}$ erg/s, for the outer jet. In the summed PWN
image, we see a faint, strongly bent, extension of the outer jet. The more
extreme bends closer to the pulsar, as well as the apparent side motions of the
outer jet, can be associated with kink instabilities of a magnetically
confined, pinched jet flow. Another feature found in the summed image is a dim,
2'-long outer counter-jet, which also shows a power-law spectrum with photon
index of 1.2-1.5. Southwest of the jet/counter-jet (i.e., approximately
perpendicular to the direction of pulsar's proper motion), an extended region
of diffuse emission is seen. Relativistic particles responsible for this
radiation are apparently supplied by the outer jet.


title: Single and Composite Hot Subdwarf Stars in the Light of 2MASS Photometry

abstract:
  Utilizing the Two Micron All Sky Survey (2MASS) Second Incremental Data
Release Catalog, we have retrieved near-IR magnitudes for several hundred hot
subdwarfs (sdO and sdB stars) drawn from the "Catalogue of Spectroscopically
Identified Hot Subdwarfs" (Kilkenny, Heber, & Drilling 1988, 1992). This sample
size greatly exceeds that of previous studies of hot subdwarfs. Examining 2MASS
photometry alone or in combination with visual photometry (Johnson BV or
Stromgren uvby) available in the literature, we show that it is possible to
identify hot subdwarf stars that exhibit atypically red IR colors that can be
attributed to the presence of an unresolved late type companion. Utilizing this
large sample, we attempt for the first time to define an approximately volume
limited sample of hot subdwarfs. We discuss the considerations, biases, and
difficulties in defining such a sample.
  We find that, of the hot subdwarfs in Kilkenny et al., about 40% in a
magnitude limited sample have colors that are consistent with the presence of
an unresolved late type companion. Binary stars are over-represented in a
magnitude limited sample. In an approximately volume limited sample the
fraction of composite-color binaries is about 30%.


title: Interactions and Mergers of Cluster Galaxies

abstract:
  The high-density environment of galaxy clusters is ripe for collisional
encounters of galaxies. While the large velocity dispersion of clusters was
originally thought to preclude slow encounters, the infall of smaller groups
into the cluster environment provides a mechanism for promoting slow encounters
and even mergers within clusters. The dynamical and star-forming response of
galaxies to a close encounter depends on both their internal structure and on
the collisional encounter speed -- fast encounters tend to trigger modest,
disk-wide responses in luminous spirals, while slow encounters are more able to
drive instabilities that result in strong nuclear activity. While the combined
effects of the cluster tidal field and ram pressure stripping make it difficult
for individual cluster galaxies to participate in many merger-driven
evolutionary scenarios, infalling groups represent a natural site for these
evolutionary processes and may represent a "preprocessing" stage in the
evolution of cluster galaxies. Meanwhile, the efficiency of tidal stripping
also drives the formation of the diffuse intracluster light in galaxy clusters;
deep imaging of clusters is beginning to reveal evidence for significant
substructure in the intracluster light.


title: Element Yields of Intermediate-Mass Stars

abstract:
  Intermediate mass stars occupy the mass range between 0.8-8 solar masses. In
this review, evolutionary models of these stars from numerous sources are
compared in terms of their input physics and predicted yields. In particular,
the results of Renzini & Voli, van den Hoek & Groenewegen, and Marigo are
discussed. Generally speaking, it is shown that yields of He-4, C-12, and N-14
decrease with increasing metallicity, reduced mass loss rate, and increased
rotation rate. Integrated yields and recently published chemical evolution
model studies are used to assess the relative importance of intermediate mass
and massive stars in terms of their contributions to universal element buildup.
Intermediate mass stars appear to play a major role in the chemical evolution
of N-14, a modest role in the case of C-12, and a small role for He-4.
Furthermore, the time delay in their release of nuclear products appears to
play an important part in explaining the apparent bimodality in the
distribution of damped Lyman alpha systems in the N/alpha--alpha/H plane.


title:
CNO Line Radiation and the X-ray Bowen Fluorescence Mechanism in
  Optically-Thick, Highly-Ionized Media

abstract:
  Radiative transfer effects due to overlapping X-ray lines in a
high-temperature, optically-thick, highly-ionized medium are investigated. One
particular example, where the O VIII Ly-alpha doublet coincide in frequency
with the N VII Ly-zeta lines is studied in detail to illustrate the effects on
the properties of the emergent line spectrum. We solve the radiative transfer
equation to study the energy transport of resonance line radiation in a static,
infinite, plane-parallel geometry, which is used to compute the
destruction/escape probabilities for each of the lines for various total
optical thicknesses of the medium, as well as destruction probabilities by
sources of underlying photoelectric opacity. It is found that a large fraction
of the O VIII Ly-alpha line radiation can be destroyed by N VII, which can
result in an reversal of the O VIII Ly-alpha/N VII Ly-alpha line intensity
ratio similar to what may be seen under non-solar abundances. Photoelectric
absorption by ionized carbon and nitrogen can also subsequently increase the
emission line intensities of these ions. We show that line ratios, which are
directly proportional to the abundance ratios in optically thin plasmas, are
not good indicators of the true CNO abundances. Conversely, global spectral
modeling that assumes optically thin conditions may yield incorrect abundance
estimates when compared to observations, especially if the optical depth is
large. Other potentially important overlapping lines and continua in the X-ray
band are also identified and their possible relevance to recent high resolution
spectroscopic observations with Chandra and XMM-Newton are briefly discussed.


title: Distances and Cosmology From Galaxy Cluster CMB Data

abstract:
  The measurement of angular diameter distance to galaxy clusters, through
combined Sunyaev-Zel'dovich (SZ) effect data with X-ray emission observations,
is now a well-known probe of cosmology. Using a combination of SZ data and a
map of the lensed CMB anisotropies by the galaxy cluster potential, we propose
an alternative geometric technique to measure distance information primarily
through cluster related multi-frequency CMB measurements. We discuss necessary
requirements to implement this measurement, potential errors including
systematic biases, and the extent to which cosmological parameters can be
extracted. While individual cluster distances are not likely to be precise,
with upcoming subarcminute resolution wide-area CMB observations, useful
information on certain cosmological parameters, such as the equation of state
of dark energy, can be obtained from a large sample of galaxy clusters.


title: The luminous and dark matter content of disk galaxies

abstract:
  For a compiled sample of disk galaxies with available photometry (B and K
bands), velocity line-widths and HI integral fluxes, several parameters which
trace the luminous, baryonic and dark matter contents were inferred. We
investigated how these parameters do vary with different galaxy properties, and
confronted the results with predictions of galaxy evolutionary models in the
context of the LCDM cosmogony. The ratio of disk-to-total maximum circular
velocity, vd/vt, depends mainly on the central disk surface density Sig_d (or
surface brightness, SB), increasing roughly as Sig_d^0.15. While a fraction of
high SB galaxies have a vd/vt ratio corresponding to the maximum disk solution,
the low SB are completely dark matter dominated. The trend is similar for the
models, although they have slightly smaller vd/vt ratios than observations. An
analysis of residuals of the vd/vt-Sig_d relation shows that vd/vt tends to
decrease as the galaxy is redder, more luminous (massive), and of earlier type.
The models allow us to explain the physics of these results, which imply a
connexion between halo structure and luminous properties. The estimated
dynamical-to-baryon mass and dynamical mass-to-light ratios at a given radius,
for observations and models, decrease with the SB and do not correlate with the
galaxy scale, contrary to what has been reported in previous works, based on
the analysis of rotation curve shapes. We discuss this difference and state the
importance to solve the controversy on whether the dark and luminous contents
in disk galaxies depend on SB or luminosity. The broad agreement between models
and observations favors the LCDM scenario. However, the excess of dark matter
inside the optical region of disk galaxies remains as the main difficulty.
(abridged)


title:
Early Structure Formation and Reionization in a Cosmological Model with
  a Running Primordial Power Spectrum

abstract:
  (abridged) We study high redshift structure formation and reionization in a
LCDM universe under the assumption that the spectral power index of primordial
density fluctuations is a function of length scale. We adopt a particular
formulation of the running spectral index (RSI) model as suggested by the
recent WMAP data. While early structure forms hierarchically in the RSI model,
the reduced power on small scales causes a considerable delay in the formation
epoch of low mass (~ 10^6 Msun) ``mini-halos'' compared to the LCDM model. The
extremely small number of gas clouds in the RSI model indicates that
reionization is initiated later than z<15, generally resulting in a smaller
total Thomson optical depth than in the LCDM model. By carrying out radiative
transfer calculations, we also study reionization by stellar populations formed
in galaxies. Even with a top-heavy intial mass function representing an early
population of massive stars and/or an extraordinarily high photon emission rate
from galaxies, the total optical depth can only be as large as tau ~ 0.1 for
reasonable models of early star-formation. The RSI model is thus in conflict
with the large Thomson optical depth inferred by the WMAP satellite.


title:
Can We Observe Galaxies that Recede Faster than Light ? -- A More
  Clear-Cut Answer

abstract:
  A more clear-cut answer to the title question is, ``Yes'' if the universal
expansion started with a big bang; ``No'' if it started infinitely slowly.


title: Migration of Trans-Neptunian Objects to the Terrestrial Planets

abstract:
  The orbital evolution of more than 22000 Jupiter-crossing objects under the
gravitational influence of planets was investigated. We found that the mean
collision probabilities of Jupiter-crossing objects (from initial orbits close
to the orbit of a comet) with the terrestrial planets can differ by more than
two orders of magnitude for different comets. For initial orbital elements
close to those of some comets (e.g. 2P and 10P), about 0.1% of objects got
Earth-crossing orbits with semi-major axes a<2 AU and moved in such orbits for
more than a Myr (up to tens or even hundreds of Myrs). Results of our runs
testify in favor of at least one of these conclusions: 1) the portion of 1-km
former trans-Neptunian objects (TNOs) among near-Earth objects (NEOs) can
exceed several tens of percents, 2) the number of TNOs migrating inside solar
system could be smaller by a factor of several than it was earlier considered,
3) most of 1-km former TNOs that had got NEO orbits disintegrated into
mini-comets and dust during a smaller part of their dynamical lifetimes if
these lifetimes are not small.


title:
The [CII] 158 um Line Deficit in Ultraluminous Infrared Galaxies
  Revisited

abstract:
  We present a study of the [CII] 157.74 um fine-structure line in a sample of
15 ultraluminous infrared (IR) galaxies (L_IR>10^12 Lsun; ULIRGs) using the
Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). We
confirm the observed order of magnitude deficit (compared to normal and
starburst galaxies) in the strength of the [CII] line relative to the far-IR
dust continuum emission found in our initial report (Luhman et al. 1998), but
here with a sample that is twice as large. This result suggests that the
deficit is a general phenomenon affecting 4/5 ULIRGs. We present an analysis
using observations of generally acknowledged photodissociation region (PDR)
tracers ([CII], [OI] 63 and 145 um, and FIR continuum emission), which suggests
that a high UV flux G_o incident on a moderate density n PDR could explain the
deficit. However, comparisons with other ULIRG observations, including CO
(1-0), [CI] (1-0), and 6.2 um polycyclic aromatic hydrocarbon (PAH) emission,
suggest that high G_o/n PDRs alone cannot produce a self-consistent solution
that is compatible with all of the observations. We propose that non-PDR
contributions to the FIR continuum can explain the apparent [CII] deficiency.
Here, unusually high G_o and/or n physical conditions in ULIRGs as compared to
those in normal and starburst galaxies are not required to explain the [CII]
deficit. Dust-bounded photoionization regions, which generate much of the FIR
emission but do not contribute significant [CII] emission, offer one possible
physical origin for this additional non-PDR component. Such environments may
also contribute to the observed suppression of FIR fine-structure emission from
ionized gas and PAHs, as well as the warmer FIR colors found in ULIRGs. The
implications for observations at higher redshifts are also revisited.


title: The Tully-Fisher Relation of Barred Galaxies

abstract:
  We present new data exploring the scaling relations, such as the Tully-Fisher
relation (TFR), of bright barred and unbarred galaxies. A primary motivation
for this study is to establish whether barredness correlates with, and is a
consequence of, virial properties of galaxies. Various lines of evidence
suggest that dark matter is dominant in disks of bright unbarred galaxies at
2.2 disk scale lengths, the point of peak rotation for a pure exponential disk.
We test the hypothesis that the TF plane of barred high surface brightness
galaxies is offset from the mean TFR of unbarred galaxies, as might be expected
if barred galaxies are ``maximal'' in their inner parts. We use existing and
new TF data to search for basic structural differences between barred and
unbarred galaxies. Our new data consist of 2-dimensional Halpha velocity fields
derived from SparsePak integral field spectroscopy (IFS) and V,I-band CCD
images collected at the WIYN Observatory for 14 strongly barred galaxies. We
use WIYN/SparsePak (2-D) velocity fields to show that long-slit (1-D) spectra
yield reliable circular speed measurements at or beyond 2.2 disk scale lengths,
far from any influence of the bar. This enables us to consider line width
measurements from extensive TF surveys which include barred and nonbarred disks
and derive detailed scaling relation comparisons. We find that for a given
luminosity, barred and unbarred galaxies have comparable structural and
dynamical parameters, such as peak velocities, scale lengths, or colors. In
particular, the location of a galaxy in the TF plane is independent of
barredness. In a global dynamical sense, barred and unbarred galaxies behave
similarly and are likely to have, on average, comparable fractions of luminous
and dark matter at a given radius. (abridged)


title: Terrestrial Planet Finding with a Visible Light Coronagraph

abstract:
  Directly imaging extrasolar planets using a monolithic optical telescope
avoids many pitfalls of space interferometry and opens up the prospect of
visible light studies of extrasolar planetary systems. Future astronomical
missions may require interferometry for high spatial resolution, but given that
the first direct imaging missions will probably fit into a single launch
vehicle, the astrophysics of planet finding calls for a visible light
coronagraph as the first space mission to search for extrasolar terrestrial
planets. New coronagraphic techniques place the necessary dynamic range within
reach for detecting planets in reflected starlight.


title:
Kaluza-Klein Burst: a New Mechanism for Generating Ultrahigh-Energy
  Cosmic Rays

abstract:
  By invoking small extra dimensions as a good energy bearer, a new scenario
for understanding the origin of ultrahigh-energy cosmic rays (UHECRs), from
both the bottom-up and the top-down viewpoints, is proposed. We explore the
possibility of generating UHECRs via Kaluza-Klein (KK) bursts, a violent energy
transfer from extra dimensions to ordinary dimensions through collisions
between KK modes, in particular, within clumps of KK modes. The possible scales
of these clumps range from the astronomical, e.g. KK stellar compact objects,
to the microscopic, e.g. "KKonium". Advantages of this KK burst model of UHECRs
and possible signatures of clumped KK modes are discussed.


title:
The multiple stellar population in omega Centauri: spatial distribution
  and structural properties

abstract:
  We present a detailed analysis of the spatial distribution of the stellar
populations in the Galactic globular cluster omega Centauri. Taking advantage
of the large photometric catalog published by Pancino et al. (2000), we confirm
that metal-rich populations have a spatial distribution which is significantly
different from the metal-poor dominant population. In particular: (i) the
different sub-populations have different centroids and (ii) the metal-poor
population is elongated along the E-W direction, while the metal-rich
populations are oriented along the orthogonal direction, i.e., N-S. The
evidence presented here can partially explain the weird spatial metallicity
segregation found by Jurcsik (1998), and further supports the hyphothesis that
different sub-populations in omega Centauri might have had different origins.


title: Acceleration Method of Neighbor Search with GRAPE and Morton-ordering

abstract:
  We describe a new method to accelerate neighbor searches on GRAPE, i.e. a
special purpose hardware that efficiently calculates gravitational forces and
potentials in $N$-body simulations. In addition to the gravitational
calculations, GRAPE simultaneously constructs the lists of neighbor particles
that are necessary for Smoothed Particle Hydrodynamics (SPH). However, data
transfer of the neighbor lists from GRAPE to the host computer is time
consuming, and can be a bottleneck. In fact, the data transfer can take about
the same time as the calculations of forces themselves. Making use of GRAPE's
special treatment of neighbor lists, we can reduce the amount of data transfer
if we search neighbors in the order that the neighbor lists, constructed in a
single GRAPE run, overlap each other. We find that the Morton-ordering requires
very low additional calculation and programming costs, and results in
successful speed-up on data transfer. We show some benchmark results in the
case of GRAPE-5. Typical reduction in transferred data becomes as much as 90%.
This method is suitable not only for GRAPE-5, but also GRAPE-3 and the other
versions of GRAPE.


title: Revealing the Nature of Dark Energy Using Bayesian Evidence

abstract:
  We apply the Bayesian concept of `evidence' to reveal systematically the
nature of dark energy from present and future supernova luminosity distance
measurements. We express the unknown dark energy equation of state w(z) as a
low order polynomial in redshift and use evidence to find the polynomial order,
thereby establishing the minimum order required by the data. We apply this
method to the current supernova data, and with a prior -1 < w(z) < 1 and
Omega_m = 0.3 \pm 0.05, obtain a large probability of 91% for the cosmological
constant model, with the remaining 9% assigned to the two more complex models
tested. We also investigate the use of evidence for future supernova data sets
such as distances obtainable from surveys like the Supernova Acceleration Probe
(SNAP). Given a low uncertainty on the present day matter density we find that,
if the underlying dark energy model is only modestly evolving, then a constant
$w(z)$ fit is sufficient. However, if the evolution of the dark energy equation
of state to linear order is larger than |w_1| ~ 0.5, then the evolution can be
established with statistical significance. For models where we can assume the
prior -1 < w(z) < 1, the correct polynomial order can be established even for
modestly evolving equations of state.


title: Photo-evaporation by thermal winds in dwarf galaxies

abstract:
  We revisit the evaporation process of gas from dwarf galaxies after it has
been photo-ionized by the UV flux from the first stars and AGNs and heated to
T~10^4K or 2x10^4K respectively. Earlier estimates, based on the balance
between pressure and gravity, indicated that dark haloes of virial velocity
lower than Vevap ~ 11-13 km/s have lost most of their gas in a dynamical time.
We follow the continuous evaporation by a thermal wind during the period when
the ionizing flux was effective. We find that the critical virial velocity for
significant evaporation is significantly higher. For example, if the ionization
starts at z-ion=10 and is maintained until z=2, a mass loss of one e-fold
occurs in haloes of Vevap ~ 25 (or 35 km/s) for T ~ 10^4K (or 2x10^4K). Haloes
of Vevap ~ 21 km/s (or 29 km/s) lose one e-fold within the first Hubble time at
z=10. Any dwarf galaxies with virial velocities smaller than Vevap must have
formed their stars from a small fraction of their gas before z-ion, and then
lost the rest of the gas by photo-evaporation. This may explain the gas-poor,
low surface brightness dwarf spheroidal galaxies. By z<1, most of the IGM gas
was evaporated at least once form dwarf galaxies, thus providing a lower bound
to its metallicity.


title: Inflation and Braneworlds

abstract:
  An introductory review of the Randall-Sundrum type II braneworld scenario is
presented, with emphasis on the relationship between the density and
gravitational wave perturbations that are generated during inflation. The
implications of relaxing the reflection symmetry in the fifth dimension are
considered. The effects of including a Gauss-Bonnet combination of higher-order
curvature invariants in the bulk action are briefly discussed.


title:
Measurement of Cosmic-Ray Proton, Antiproton and Muon Spectra at
  Mountain Altitude

abstract:
  Measurement of cosmic-ray proton, antiproton and muon spectra was carried out
at mountain altitude. We observed 2 x 10^5 protons and 10^2 antiprotons in a
kinetic energy region of 0.25 -- 3.3 GeV. Zenith-angle dependence of proton
fluxes was obtained. Atmospheric muon spectra were measured simultaneously. The
observed antiproton spectrum showed some deviation from theoretical predictions
particularly in a low energy region.


title:
Dynamical modelling of a remarkable four-armed barred spiral galaxy ESO
  566-24

abstract:
  ESO 566-24 is an extraordinary barred galaxy, which has four regularly spaced
spiral arms in blue light images. This type of four-armed spiral structure,
which is rare among the spiral population, is clearly seen also in
near-infrared images, and thus is present in the old stellar population. We
have constructed dynamical models of ESO 566-24 in order to understand the
cause of its four-armed structure. The disk gravitational potential is
determined from near-infrared photometry, and the gas dynamics is modelled as
inelastically colliding particles. The resulting morphology and kinematics with
different assumed pattern speeds, disk vertical thicknesses and dark halo
contributions is compared with observations. Our models can reproduce the main
morphological features of this galaxy: the four-armed spiral, and the inner and
nuclear rings. The pattern speed of the bar in this galaxy is such that the
corotation resonance is well outside the bar radius, the resonance radius is
1.6 +/- 0.3 times the bar radius. The four-armed spiral resides in the region
between inner and outer 4/1-resonances. Also, the main kinematical features,
including bar-induced deviations from circular rotation, are explained by our
models. The best fit is obtained when the dark halo contribution is just enough
to make the modelled rotation curve match the observed one. This ``minimum
halo'' is rather moderate: luminous matter dominates the rotation curve within
the disk region.


title:
The age, life expectancy, and space density of Post Common Envelope
  Binaries

abstract:
  We present a sample of 30 well observed Post Common Envelope Binaries
(PCEBs). Deriving the cooling age of the white dwarfs, we show that the PCEB
population is dominated by young systems. Having calculated the orbital
evolution of the systems under the assumption of two different prescriptions
for the angular momentum loss, we find that most of the systems have not yet
completed a significant fraction of their PCEB life time. We therefore predict
the existence of a large population of old PCEBs containing cold white dwarfs
(T_eff<15000 K). Our calculations show that nearly half of the PCEBs in our
sample will evolve into a semi-detached configuration and start mass transfer
in less than the Hubble-time. These systems are thus representative for
progenitors of the current CV population. Only one of them (V471 Tau) will
evolve into a long-period (Porb>4h) CV, and a significant fraction of the
systems will start mass transfer in the period gap. Having estimated the
distances of the PCEBs in the sample, we derive a space density of ~6-30x1e-6
[pc-3], depending on the assumed angular momentum loss prescription. Taking
into account the evolutionary time scales we compute a lower limit for the CV
space density, predicted by the currently known PCEB population of ~10 x 1e-5
[pc-3]. Finally, we discuss possible observational selection effects and
conclude that the observed PCEB population is probably highly incomplete.


title:
SEDs of flared dust disks: radiation transfer model versus two-layer
  model

abstract:
  A radiation transfer model for the top-layer of a flared dust disk around a
low mass star is presented. The disk structure, temperature distribution and
spectral energy distribution are compared with the results of the analytical
two-layer model of Chiang & Goldreich. We find that both, a proper iterative
calculation of the main parameters and proper radiation transfer calculations,
are important to not overestimate the disk structure and its emission
especially at long wavelengths.


title:
The Ecosphere and the Value of the Electromagnetic Fine Structure
  Constant

abstract:
  Following the coincidence A x atomic year ~ Earth year (s), (A = Avogardo
number, atomic year=a_B/alpha c, a_B=Bohr radius, alpha= fine structure
constant, c=light velocity) and considering the "niche" for alpha, i.e.
180^{-1}<alpha<85^{-1}, the Ecosphere radius is calculated. Key words: Fine
structure constant; Planet orbit radii.


title: Axion searches at CERN with the CAST Telescope

abstract:
  The CERN Axion Solar Telescope (CAST) searches for axions coming from photon
to axion conversion in the sun's core, as stated by the Primakoff effect.
Axions arise in particle physics as a consequence of the breaking of
Peccei-Quinn symmetry which has been introduced as a solution to the strong CP
problem. As cosmological axions they are candidates for at least some part of
cold Dark Matter.They are also expected to be produced copiously in stellar
interiors with energies as high as the thermal photons undergoing photon to
axion conversion. In our sun the axion energy spectrum peaks at about 4.4 keV,
extending up to 10 keV. CAST collected preliminary data in 2002 and data taking
with its full capability will start in the beginning of 2003.


title:
The Hamburg/RASS Catalogue of optical identifications. Northern
  high-galactic latitude ROSAT Bright Source Catalogue X-ray sources

abstract:
  We present the Hamburg/RASS Catalogue (HRC) of optical identifications of
X-ray sources at high-galactic latitude. The HRC includes all X-ray sources
from the ROSAT Bright Source Catalogue (RASS-BSC) with galactic latitude |b| >=
30 degr and declination delta >= 0 degr. In this part of the sky covering ~10
000 deg^2 the RASS-BSC contains 5341 X-ray sources. For the optical
identification we used blue Schmidt prism and direct plates taken for the
northern hemisphere Hamburg Quasar Survey (HQS) which are now available in
digitized form. The limiting magnitudes are 18.5 and 20, respectively. For 82%
of the selected RASS-BSC an identification could be given. For the rest either
no counterpart was visible in the error circle or a plausible identification
was not possible. With ~42% AGN represent the largest group of X-ray emitters,
\~31% have a stellar counterpart, whereas galaxies and cluster of galaxies
comprise only ~4% and ~5%, respectively. In ~3% of the RASS-BSC sources no
object was visible on our blue direct plates within 40 arcsec around the X-ray
source position. The catalogue is used as a source for the selection of
(nearly) complete samples of the various classes of X-ray emitters.


title: Masses and orbital inclinations of planets in the PSR B1257+12 system

abstract:
  We present measurements of the true masses and orbital inclinations of the
two Earth-mass planets in the PSR B1257+12 system, based on the analysis of
their mutual gravitational perturbations detectable as microsecond variations
of the arrival times of radio pulses from the pulsar. The 6.2-millisecond
pulsar, PSR B1257+12, has been regularly timed with the Arecibo telescope since
late 1990. Assuming the standard pulsar mass of 1.4 M_Sun, the derived masses
of planets B and C are 4.3 +/- 0.2 M_Earth and 3.9 +/- 0.2 M_Earth,
respectively. The corresponding orbital inclinations of 53.4 and 47.3 deg (or
127 and 133 deg) imply that the two orbits are almost coplanar. This result,
together with the known near 3:2 resonance between the orbits of the two
planets, strongly supports the hypothesis of a disk origin of the PSR B1257+12
planetary system. The system's long-term stability is guaranteed by the low,
Earth-like masses of planets B and C.


title: Gauss--Legendre Sky Pixelization (GLESP) for CMB maps

abstract:
  A new scheme of sky pixelization is developed for CMB maps. The scheme is
based on the Gauss--Legendre polynomials zeros and allows one to create strict
orthogonal expansion of the map. A corresponding code has been implemented and
comparison with other methods has been done.


title:
Luminous hot accretion flows: thermal equilibrium curve and thermal
  stability

abstract:
  In a previous paper, we presented the global solution of a new accretion flow
model, namely luminous hot accretion flows (LHAFs). In this {\em Letter}, we
first show the corresponding thermal equilibrium curve of LHAFs in the mass
accretion rate vs. surface density diagram. Then we examine its thermal
stability again local perturbations. We find that LHAFs are thermally unstable
when thermal conduction is neglected. However, when the accretion rate is not
very large, the timescale of the growth of perturbations is longer than the
accretion timescale, therefore the instability has no dynamical effect on the
accretion flow. When the accretion rate is large, the perturbations can grow
very fast at a certain radius. As a result, some cold clumps may form and the
accretion flow will become multi-phase.


title:
Constraints on stellar convection from multi-colour photometry of Delta
  Scuti stars

abstract:
  In Delta Scuti star models, the calculated amplitude ratios and phase
differences for multi-colour photometry exhibit a strong dependence on
convection. These observables are tools for determination of the spherical
harmonic degree of the excited modes. The dependence on convection enters
through the complex parameter f, which describes bolometric flux perturbation.
We present a method of simultaneous determination of f and spherical harmonic
degree from multi-colour data and apply it to three Delta Scuti stars. The
method indeed works. Determination of the degree appears unique and the
inferred f's are sufficiently accurate to yield a useful constraint on models
of stellar convection. Furthermore, the method helps to refine stellar
parameters, especially if the identified mode is radial.


title: Search for the Optical Counterpart of the Vela Pulsar X-ray Nebula

abstract:
  Observations of the Vela pulsar region with the Chandra X-ray observatory
have revealed the fine structure of its synchrotron pulsar-wind nebula (PWN),
which showed an overall similarity with the Crab PWN. However, contrary to the
Crab, no firm detection of the Vela PWN in optical has been reported yet. To
search for the optical counterpart of the X-ray PWN, we analyzed deep optical
observations performed with different telescopes. We compared the optical
images with those obtained with the Chandra ACIS to search for extended
emission patterns which could be identified as counterparts of the X-ray nebula
elements. Although some features are seen in the optical images, we find no
correlation with the X-ray structure. Thus, we conclude that the diffuse
optical emission is more likely associated with filaments in the host Vela SNR.
The derived upper limits on the optical flux from the PWN are compatibile,
within the uncertainties, with the values expected on the basis of the
extrapolations of the X-ray data.


title: Black Hole Winds

abstract:
  We show that black holes accreting at or above the Eddington rate probably
produce winds which are optically thick in the continuum, whether in quasars or
X-ray binaries. The photospheric radius and outflow speed are proportional to
\mo^2 and \mo^-1 respectively, where \mo is the mass outflow rate. The outflow
momentum rate is always of order L_Edd/c. Blackbody emission from these winds
may provide the big blue bump in some quasars and AGN, as well as ultrasoft
X-ray components in ULXs.


title: DAMA results

abstract:
  DAMA is an observatory for rare processes based on the development and use of
various kinds of radiopure scintillators. Several low background set-ups have
been realized with passing and many rare processes have been investigated. Main
activities are briefly summarized in the following and the main arguments on
the results achieved in the investigation of the WIMP annual modulation
signature are addressed. Next perspectives are also mentioned.


title: VLBI observations of T Tauri S

abstract:
  We report observations of the T Tauri system at 8.4 GHz with a VLBI array
comprising the VLBA, VLA and Effelsberg 100m telescopes. We detected a compact
source offset approximately 40 mas from the best infrared position of the T Tau
Sb component. This source was unresolved, and constrained to be less than 0.5
mas in size, corresponding to 0.07 AU or 15 R$_{\odot}$ at a distance of 140
pc. The other system components (T Tau Sa, T Tau N) were not detected in the
VLBI data. The separate VLA map contains extended flux not accounted for by the
compact VLBI source, indicating the presence of extended emission on arcsecond
scales. The compact source shows rapid variability, which together with
circular polarization and its compact nature indicate that the observed flux
arises from a magnetically-dominated region. Brightness temperatures in the MK
range point to gyrosynchrotron as the emission mechanism for the steady
component. The rapid variations are accompanied by dramatic changes in
polarization, and we record an at times 100% polarized component during
outbursts. This strongly suggests a coherent emission process, most probably an
electron cyclotron maser. With this assumption it is possible to estimate the
strength of the local magnetic field to be 1.5-3 kilogauss.


title: Redshifts in the Hubble Deep Field South

abstract:
  We present a catalog of 97 spectroscopic redshifts of z<1 galaxies in the
Hubble Deep Field South (HDFS) and its Flanking Fields (FFs). In the HDFS
proper, we observed approximately half the galaxies brighter than I(AB)=24 and
obtained redshifts for 76% of them. Targets in our HDFS sample were
pre-selected to be at z<1 based on photometric redshifts, while in the FFs a
simple magnitude cut was used. The photometric redshift pre-selection in the
HDFS resulted in a spectroscopic success rate that is significantly higher than
in the FFs, where no pre-selection was applied. The RMS precision of our
redshift measurements, determined from repeat observations, is delta_z=0.0003.
We present the photometry and redshifts for the 97 objects for which we secured
spectroscopic redshifts and describe the basic properties of this sample.


title: Harmonic E/B decomposition for CMB polarization maps

abstract:
  The full sky cosmic microwave background polarization field can be decomposed
into 'electric' (E) and 'magnetic' (B) components that are signatures of
distinct physical processes. We give a general construction that achieves
separation of E and B modes on arbitrary sections of the sky at the expense of
increasing the noise. When E modes are present on all scales the separation of
all of the B signal is no longer possible: there are inevitably ambiguous modes
that cannot be separated. We discuss the practicality of performing E/B
decomposition on large scales with realistic non-symmetric sky-cuts, and show
that separation on large scales is possible by retaining only the well
supported modes. The large scale modes potentially contain a great deal of
useful information, and E/B separation at the level of the map is essential for
clean detection of B without confusion from cosmic variance due to the E
signal. We give simple matrix manipulations for creating pure E and B maps of
the large scale signal for general sky cuts. We demonstrate that the method
works well in a realistic case and give estimates of the performance with data
from the Planck satellite. In the appendix we discuss the simple analytic case
of an azimuthally symmetric cut, and show that exact E/B separation is possible
on an azimuthally symmetric cut with a finite number of non-intersecting
circular cuts around foreground sources.


title: Simulations of Gaseous Disc-Embedded Planet Interaction

abstract:
  We present three-dimensional self-gravitating smoothed-particle hydrodynamics
(SPH) simulations of an isothermal gaseous disc interacting with an embedded
planet. Discs of varying stability are simulated with planets ranging from 10
Earth-masses to 2 Jupiter-masses. The SPH technique provides the large dynamic
range needed to accurately capture the large scale behavior of the disc as well
as the small scale interaction of the planet with surrounding material. Most
runs used 10^5 gas particles, giving us the spatial resolution required to
observe the formation of planets. We find four regions in parameter space:
low-mass planets undergo Type I migration; higher-mass planets can form a gap;
the gravitational instability mode of planet formation in marginally stable
discs can be triggered by embedded planets; discs that are completely unstable
can fragment to form many planets. The disc stability is the most important
factor in determing which interaction a system will exhibit. For the stable
disc cases, our migration and accretion time-scales are shorter and scale
differently than previously suggested.


title: Extracting the Dark Matter Profile of a Relaxed Galaxy Cluster

abstract:
  Knowledge of the structure of galaxy clusters is essential for an
understanding of large scale structure in the universe, and may provide
important clues to the nature of dark matter. Moreover, the shape of the dark
matter distribution in the cluster core may offer insight into the structure
formation process. Unfortunately, cluster cores also tend to be the site of
complicated astrophysics. X-ray imaging spectroscopy of relaxed clusters, a
standard technique for mapping their dark matter distributions, is often
complicated by the presence of cool components in cluster cores, and the dark
matter profile one derives for a cluster is sensitive to assumptions made about
the distribution of this component. In addition, fluctuations in the
temperature measurements resulting from normal statistical variance can produce
results which are unphysical. We present here a procedure for extracting the
dark matter profile of a spherically symmetric, relaxed galaxy cluster which
deals with both of these complications. We apply this technique to a sample of
galaxy clusters observed with the Chandra X-ray Observatory, and comment on the
resulting mass profiles. For some of the clusters we compare their masses with
those derived from weak and strong gravitational measurements.


title:
Cosmological Perturbations From Inhomogeneous Reheating, Freeze-Out, and
  Mass Domination

abstract:
  We generalize a recently proposed mechanism for the origin of primordial
metric perturbations in inflationary models. Quantum fluctuations of light
scalar fields during inflation give rise to super-horizon fluctuations of
masses and reaction rates of various particles. Reheating, freeze-out, and
matter-domination processes become inhomogeneous and generate super-horizon
metric perturbations. We also calculate the degree of non-Gaussianity $f_{nl}$
for this new model of cosmological perturbations. The precise value of $f_{nl}$
depends on the specific models, but $|f_{nl}|\sim$few is a natural lower bound
for our mechanisms. This is much larger than the currently assumed theoretical
value $f_{nl}\sim tilt \lesssim 0.05$, and is thought to be observable. In a
particularly attractive model of inhomogeneous mass-domination, the
non-Gaussianity of perturbations generated by our mechanism is simply
$f_{nl}=5$, irrespective of the detailed structure of the underlying field
theory.


title:
Constraining amplitude and slope of the mass fluctuation spectrum using
  cluster baryon mass function

abstract:
  We derive the baryon mass function for a complete sample of low-redshift
clusters and argue that it is an excellent proxy for the total mass function if
the ratio f_b=M_b/M_tot in all clusters is close to its universal value,
Omega_b/Omega_M. Under this assumption, the baryon mass function can be used to
constrain the amplitude and slope of the density fluctuations power spectrum on
cluster scales. This method does not use observational determinations of the
total mass and thus bypasses major uncertainties in the traditional analyses
based on the X-ray temperature function. However, it is sensitive to possible
systematic variations of the baryon fraction as a function of cluster mass.
Adapting a weak dependence f_b(M) suggested by observations and numerical
simulations by Bialek et al., we derive sigma_8=0.72+-0.04 and the shape
parameter Omega_M*h=0.13+-0.07, in good agreement with a number of independent
methods. We discuss the sensitivity of these values to other cosmological
parameters and to different assumptions about variations in f_b.


title:
Methods for Constraining Fine Structure Constant Evolution with OH
  Microwave Transitions

abstract:
  We investigate the constraints that OH microwave transitions in megamasers
and molecular absorbers at cosmological distances may place on the evolution of
the fine structure constant alpha=e^2/(hbar c). The centimeter OH transitions
are a combination of hyperfine splitting and lambda-doubling that can constrain
the cosmic evolution of alpha from a single species, avoiding systematic errors
in alpha measurements from multiple species which may have relative velocity
offsets. The most promising method compares the 18 and 6 cm OH lines, includes
a calibration of systematic errors, and offers multiple determinations of alpha
in a single object. Comparisons of OH lines to the HI 21 cm line and CO
rotational transitions also show promise.


title: Confirmation of solar-like oscillations in eta Bootis

abstract:
  We obtained time-series spectroscopy of the G0 subgiant eta Boo in an attempt
to confirm the solar-like oscillations reported by Kjeldsen et al. (1995). We
recorded 1843 spectra over six consecutive nights with the Nordic Optical
Telescope, which we used to measure equivalent widths of strong
temperature-sensitive lines. We also measured velocities from 1989 spectra
obtained through an iodine reference cell at Lick Observatory over 56 nights
that were badly affected by weather. Our analysis also included velocity
measurements published by Brown et al. (1997) and the original equivalent-width
measurements by Kjeldsen et al. (1995). All four data sets show power excesses
consistent with oscillations, although with a range of amplitudes that
presumably reflects the stochastic nature of the excitation. The highest peaks
show regularity with a large separation of Delta nu = 40.4 microHz and we
identify 21 oscillation frequencies from the combined data.


title:
Molecular Gas and the Nuclear Star Cluster in IC342: Sufficient Inflow
  for Recurring Star Formation Events?

abstract:
  We present high spatial resolution (1.2") mm-interferometric observations of
the CO(2-1) line emission in the central 300pc of the late-type spiral galaxy
IC342. The data, obtained with the Owens Valley Radio Observatory, allow
first-time detection of a molecular gas disk that coincides with the luminous
young stellar cluster in the nucleus of IC342. The nuclear CO disk has a
diameter of ~30pc and a molecular gas mass of M(H2) ~ 2x10^5 M_sun. It connects
via two faint CO bridges to the well-known, 100pc diameter circumnuclear gas
ring. Analysis of the gas kinematics shows that the line-of-nodes in the inner
15pc is offset by about 45degree from the major kinematic axis, indicating
non-circular motion of the gas within a few parsec of the dynamical center of
IC342. Both the morphology and the kinematics of the CO gas indicate ongoing
inflow of molecular gas into the central few parsec of IC342. We infer a gas
inflow rate between 0.003 and 0.14 M_sun/yr, based on the observed surface
density of the nuclear gas disk and estimates of the radial velocities of the
surrounding gas. Inflow rates of this order can support repetitive star
formation events in the nucleus of IC342 on timescales much smaller than a
Hubble time.


title: First Results from the Arcminute Cosmology Bolometer Array Receiver

abstract:
  We review the first science results from the Arcminute Cosmology Bolometer
Array Receiver (ACBAR); a multifrequency millimeter-wave receiver optimized for
observations of the Cosmic Microwave Background (CMB) and the
Sunyaev-Zel'dovich (SZ) effect in clusters of galaxies. ACBAR was installed on
the 2 m Viper telescope at the South Pole in January 2001 and the results
presented here incorporate data through July 2002. We present the power
spectrum of the CMB at 150 GHz over the range \ell = 150 - 3000 measured by
ACBAR as well as estimates for the values of the cosmological parameters within
the context of Lambda-CDM models. We find that the inclusion of Omega_Lambda
greatly improves the fit to the power spectrum. We also observe a slight excess
of small-scale anisotropy at 150 GHz; if interpreted as power from the SZ
effect of unresolved clusters, the measured signal is consistent with CBI and
BIMA within the context of the SZ power spectrum models tested.


title: LSR1610-0040: the first early-type L subdwarf

abstract:
  We report the discovery of LSR1610-0040, a previously unreported r=17.5 star
with a very high proper motion mu=1.46"/yr. This very cool star (b-i=6.3) is
found to have a peculiar spectrum that does not fit into the standard sequence
of late-M dwarfs and L dwarfs. Rather, the spectrum is more typical of an
ultra-cool subdwarf, with weak bands of TiO and no detectable VO. But because
LSR1610-0040 is so much redder than any other sdM known, and because it does
not appear to fit well into the sdM sequence, we propose that LSR1610-0040 be
assigned a spectral type sdL, making it the first early-type L subdwarf known.
Evidence suggests that LSR1610-0040 is an old, metal-poor star whose mass is
just above the limit of hydrogen burning (M ~ 0.08 M_sun).


title:
Nucleosynthesis of Light Elements and Heavy r-Process Elements through
  the nu-Process in Supernova Explosion

abstract:
  We study the nucleosyntheses of the light elements 7Li and 11B and the
r-process elements in Type II supernovae from the point of view of supernova
neutrinos and Galactic chemical evolution. We investigate the influence of the
luminosity and average energy (temperature) of supernova neutrinos on these two
nucleosynthesis processes. Common models of the total energy E_nu and the decay
time of the neutrino luminosity tau_nu of supernova neutrinos are adopted to
understand both processes. We adopt the model of the supernova explosion of a
16.2 M_odot star, which corresponds to SN 1987A, and calculate the
nucleosynthesis of the light elements by the postprocessing. We find that the
ejected masses of 7Li and 11B are roughly proportional to the total neutrino
energy and weakly dependent on the decay time of the neutrino luminosity. As
for the r-process nucleosynthesis, we adopt the same models of the neutrino
luminosity in the neutrino-driven wind models of a 1.4 M_odot neutron star. We
find that the r-process nucleosynthesis is affected through the peak neutrino
luminosity, which depends on E_nu/tau_nu. We also discuss the unresolved
problem of the overproduction of 11B in the Galactic chemical evolution of the
light elements. We have to assume E_{nu} < 1.2 \times 10^{53} ergs to avoid the
overproduction of 11B, which is too small to accept in comparison to 3.0 \times
10^{53} ergs deduced from the observation of SN1987A. We propose to reduce the
temperature of nu_{mu, tau} and their anti-particles to T_{nu_{mu, tau}} =
T_{bar{nu}_{mu,tau}} = 6.0 MeV/k. This modification of the neutrino temperature
is shown to resolve the overproduction problem of 11B while still keeping a
successful r-process abundance pattern.


title:
Implications of the WMAP Age Measurement for Stellar Evolution and Dark
  Energy

abstract:
  The WMAP satellite has provided a new measurement of the age of the Universe,
of $13.7 \pm 0.2$ Gyr. A comparison of this limit with constraints from stellar
evolution imply that the oldest globular clusters in the Milky Way galaxy have
a reasonable probability of have formed significantly after reionization. At
the same time, one can derive a direct {\it upper limit} on the time after the
big bang before globular clusters in our galaxies formed of $\approx 3$ Gyr,
which significantly reduces our uncertainty since before the CMB age estimate.
The WMAP age constraint can also be shown to provide a stringent {\it lower
bound} on the equation of state of dark energy. A precise value of this lower
bound would require a global analysis of the WMAP parameter constraints.
However, making conservative assumptions about allowed parameter ranges and
correlations one derives a lower bound of $ w > -1.22$. Combining this with the
WMAP-quoted upper limit on $w$ thus gives roughly symmetric 95% confidence
range $w =-1 \pm 0.22$.


title:
Vacuum nonlinear electrodynamic effects in hard emission of pulsars and
  magnetars

abstract:
  The possibilities of observing some nonlinear electrodynamic effects, which
can be manifested in hard emission of X-ray, gamma ray pulsars and magnetars by
X-ray and gamma ray astronomy methods are discussed. The angular resolution and
sensitivity of modern space observatories give the opportunity to study the
nonlinear electrodynamic effects, which can occur in very strong magnetic
fields of pulsars ($B\sim 10^{12}$ G) and magnetars ($B\sim 10^{15}$ G). Such
magnetic field magnitudes are comparable with the typical value of magnetic
field induction necessary for manifestation of electrodynamics non-linearity in
vacuum. Thus, near a magneticneutron star the electromagnetic emission should
undergo nonlinear electrodynamic effects in strong magnetic fields (such as
bending of rays, fluxes dispersing, changing of spectra and polarization
states). Manifestations of these effects in detected hard emission from
magnetic neutron stars are discussed on the base of nonlinear generalizations
of the Maxwell equation in vacuum. The dispersion equations for electromagnetic
waves propagating in the magnetic dipole field were obtained in the framework
of these theories.The possibility of observing the bending of a ray and gamma
ray flux dispersing in the neutron star magnetic field are analyzed. The only
nonlinear electrodynamicseffect, which can be measured principally, is the
effect of gamma ray flux dispersion by the neutron star magnetic field.
Studying this effect we can also obtain information on the nonlinear
electrodynamics bending of a ray in the source. The main qualitative difference
in predictions of different nonlinear electrodynamics theories are discussed.


title: Identification of Showers with Cores Outside the ARGO-YBJ Detector

abstract:
  In any EAS array, the rejection of events with shower cores outside the
detector boundaries is of great importance. A large difference between the true
and the reconstructed shower core positions may lead to a systematic
miscalculation of some shower characteristics. Moreover, an accurate
determination of the shower core position for selected internal events is
important to reconstruct the primary direction using conical fits to the shower
front, improving the detector angular resolution, or to performe an efficient
gamma/hadron discrimination. In this paper we present a procedure able to
identify and reject showers with cores outside the ARGO-YBJ carpet boundaries.
A comparison of the results for gamma and proton induced showers is reported.


title: You need not be afraid of phantom energy

abstract:
  Phantom energy which violates the dominant-energy condition and is not
excluded by current constraints on the equation of state may be dominating the
evolution of the universe now. It has been pointed out that in such a case the
fate of the universe may be a big rid where the expansion is so violent that
all galaxies, planet and even atomic nuclei will be successively ripped apart
in finite time. Here we show however that there are certain unified models for
dark energy which are stable to perturbations in matter density where the
presence of phantom energy does not lead to such a cosmic doomsday.


title:
Sensitivity of the ARGO-YBJ strip size spectrum to different models of
  the primary cosmic ray composition in the energy range 10 - 500 TeV

abstract:
  The ARGO-YBJ experiment is currently under construction at the Yangbajing
Cosmic Ray Laboratory (4300 m a.s.l.). The detector will cover 74 X 78 m^2 with
a single layer of Resistive Plate Counters (RPCs), surrounded by a partially
instrumented guard ring. Signals from each RPC are picked-up with 80 read out
strips 6 cm wide and 62 cm long. These strips allow one to count the particle
number of small size air showers. In this paper we discuss the digital response
of the detector for showers with core located in a small fiducial area inside
the carpet. The results enable us to assess the sensitivity of the strip size
spectrum measurement to discriminate between different models of the Primary
Cosmic Ray composition in the energy range 10 - 500 TeV.


title: TNG photometry of the open cluster NGC 6939

abstract:
  We present CCD UBVI photometry of the intermediate age open cluster NGC 6939
for three TNG-DOLORES fields. The fields A and B cover the center of the
cluster; the third one is located about 30 arcmin away, and is used for field
stars decontamination.
  The V-I, B-V and U-B color-magnitude diagrams (CMDs), obtained joining very
different exposures show: i) a Main Sequence (MS) extending down to V = 24,
much deeper (~ 5 magnitudes) than any previous study; ii) a clearly defined
Turn Off (TO) and iii) a well populated Red Giant Clump (RC) at about V = 13.


title: Cosmology from the Top Down

abstract: Cosmology from the Top Down.


title: The Luminous X-ray Source Population in M51 Observed with Chandra

abstract:
  We present the results of two Chandra observations (separated by 1 year) of
the population of X-ray sources in the spiral galaxy M51 (NGC 5194 and NGC
5195). 113 X-ray sources have been detected in an 8'.4x8'.4 region. Nine and 28
sources have luminosities exceeding 10^39 erg/s (ULXs) and 10^38 erg/s in the
0.5-8 keV band, respectively, assuming they are associated with M51. The number
of ULXs is much higher than found in most normal spiral and elliptical
galaxies. Most of the X-ray sources and all seven of the ULXs in NGC 5194 are
located in, or close to, a spiral arm, suggesting a connection with recent star
formation. The cumulative luminosity function of the X-ray sources in NGC 5194
with Lx>10^38 erg/s is well described by a power law N(>Lx) \propto Lx^-\alpha
with \alpha=0.91. The X-ray spectra of most of the detected sources are
consistent with a power law with a photon index between 1 and 2, with a few
sources showing harder or softer spectra. The spectra of most ULXs are
consistent with both a power law and a multicolor disk blackbody (MCD) model,
while a power law model is preferable to a MCD model in two ULXs. A drastic
spectral variability and emission lines in ULXs are also presented. The masses
of the compact objects and mass accretion rates in ULXs and other X-ray sources
are not well constrained by these observations. If we adopt a MCD
interpretation, their MCD parameters imply that most of the X-ray sources are
stellar mass (~5-10 M_solar) black holes accreting near or above the Eddington
rate.(abridged)