title: Black hole masses in narrow-line Seyfert 1 galaxies

abstract:
  The masses of central supermassive black holes in a soft X-ray selected
sample of the narrow-line Seyfert 1 galaxies (NLS1s) are estimated by some
different methods to test their theoretical models. Apart from the methods
using the H$\beta$ linewidth and the [O III] linewidth, soft X-ray excess as a
prominent character of NLS1s is used to estimate the black hole masses. The
virial mass derived from the H$\beta$ linewidth assuming random orbits of
broad-line reigns (BLRs) is consistent with that from the soft X-ray bump
luminosity for NLS1s but with a larger scatter. The virial black hole masses
showed that most of NLS1s are in the super-Eddington accretion state while most
of broad-line Seyfert 1 galaxies (BLS1s) are not. We found that the black hole
mass estimated from [O III] linewidth is not in agreement with above two
methods. Using the Eddington limit relation for the super-Eddington accretion
suggested by Wang (2004), we found that there are 16 NLS1s satisfied with this
Eddington limit relation. The masses of these 16 NLS1s derived from X-ray
luminosity are systematically larger than that from H$\beta$ linewidth assuming
random BLRs orbits. If the mass derived from X-ray luminosity is true, the mean
disk inclination to the line of sight in these 16 NLS1s is about $17^{\circ}$,
which provided new support for the pole-on orientation effect in NLS1s.


title: Bipolar outflow on the Asymptotic Giant Branch - the case of IRC+10011

abstract:
  Near-IR imaging of the AGB star IRC+10011 (= CIT3) reveals the presence of a
bipolar structure within the central ~0.1 arcsec of a spherical dusty wind. We
show that the image asymmetries originate from ~1E-4 Msun of swept-up wind
material in an elongated cocoon whose expansion is driven by bipolar jets. We
perform detailed 2D radiative transfer calculations with the cocoon modeled as
two cones extending to ~1,100 AU within an opening angle of ~30deg, imbedded in
a wind with the standard r^{-2} density profile. The cocoon expansion started
<~200 years ago, while the total lifetime of the circumstellar shell is ~5,500
years. Similar bipolar expansion, at various stages of evolution, has been
recently observed in a number of other AGB stars, culminating in jet breakout
from the confining spherical wind. The bipolar outflow is triggered at a late
stage in the evolution of AGB winds, and IRC+10011 provides its earliest
example thus far. These new developments enable us to identify the first
instance of symmetry breaking in the evolution from AGB to planetary nebula.


title: Theory of disk accretion onto supermassive black holes

abstract:
  Accretion onto supermassive black holes produces both the dramatic phenomena
associated with active galactic nuclei and the underwhelming displays seen in
the Galactic Center and most other nearby galaxies. I review selected aspects
of the current theoretical understanding of black hole accretion, emphasizing
the role of magnetohydrodynamic turbulence and gravitational instabilities in
driving the actual accretion and the importance of the efficacy of cooling in
determining the structure and observational appearance of the accretion flow.
Ongoing investigations into the dynamics of the plunging region, the origin of
variability in the accretion process, and the evolution of warped, twisted, or
eccentric disks are summarized.


title: Starburst-AGN Connection: A Lesson from High-z Powerful Radio Galaxies

abstract:
  Powerful radio galaxies at high redshift are highly useful in studies of
early evolution of AGN-hosting galaxies because their observed optical and near
infrared light are dominated by their stellar population rather than the
nonthermal continuum emitted by the central engine of AGNs. In addition, the
presence of AGN activity in them implies that a supermassive black hole has
been already made in their nuclei. These properties allow us to investigate a
possible starburst-AGN connection in early universe and then provide some
crucial hints for the formation mechanism of supermassive black holes. Taking
observational properties of high-z powerful radio galaxies into account, we
discuss a possible formation mechanism of supermassive black holes in their
nuclei.


title:
Reflection Component in the Hard X-Ray Emission from the Seyfert 2
  Galaxy Mrk 1210

abstract:
  The Seyfert 2 galaxy Mrk 1210 was found to exhibit a flat hard X-ray
component by ASCA, although ASCA could not distinguish whether it is an
absorbed direct component or a reflected one. We then observed Mrk 1210 with
BeppoSAX, and found that the X-ray spectral properties are quite different from
those of ASCA, as have been confirmed with XMM-Newton; the flux is
significantly higher than that in the ASCA observation, and a clear absorption
cut-off appears below 5 keV. A bright hard X-ray emission is detected up to 100
keV. The reflection component is necessary to describe the BeppoSAX PDS
spectrum, and represents the ASCA hard component very well. Therefore, the hard
component in the ASCA spectrum is a reflected one, whose intensity is almost
constant over 6 years. This indicates that a dramatic spectral variability is
attributed to a large change of the absorption column density by a factor of
>5, rather than the variability of the nuclear emission. The change in the
absorption-column density means that the torus is not homogeneous, but has a
blobby structure with a typical blob size of < 0.001


title:
Structure and kinematics of edge-on galaxy discs -- II. Observations of
  the neutral hydrogen

abstract:
  We present Australia Telescope Compact Array (ATCA) and Westerbork Synthesis
Radio Telescope (WSRT) HI observations of 15 edge-on spiral galaxies of
intermediate to late morphological type. The global properties and the
distribution and kinematics of the HI gas are analysed and discussed. We
determine the rotation curves using the envelope-tracing method. For 10 spiral
galaxies with a stellar disc truncation we find an average ratio of the HI
radius to the truncation radius of the stellar disc of 1.1 +/- 0.2 (1 sigma).
  This paper has been accepted by MNRAS and is available in pdf-format at the
following URL: http://www.astro.rug.nl/$\sim $vdkruit/jea3/homepage/paperII.pdf


title:
Structure and kinematics of edge-on galaxy discs -- III. The rotation
  curves in the gas

abstract:
  A technique is introduced for deriving the gaseous rotation curves of edge-on
spiral galaxies. The entire major axis position-velocity (XV) diagram is
modeled with a set of rings in a least-squares sense, allowing for the effects
of beam-smearing and line-of-sight projection. The feasibility of the technique
is demonstrated by applying it to good quality HI XV diagrams of eight edge-on
spirals. For seven additional spirals the XV diagrams are of insufficient
quality, and the HI rotational velocities derived earlier using the
envelope-tracing method are retained. The HI results are augmented with the
optical emission line (HII) kinematics to arrive at estimates of the full
rotation curves. A detailed comparison of the HI and HII kinematics shows that
the discs in our sample are sufficiently transparent at the heights above the
plane where we have taken our optical spectra to derive the stellar kinematics.
In several of these spirals the HII is mainly confined to spiral arms and does
not extend out to the edge of the HI layer, which may have caused the HII
velocity profiles to be significantly narrower than those of the HI.
  This paper has been accepted by MNRAS and is available in pdf-format at the
following URL: http://www.astro.rug.nl/$\sim
$vdkruit/jea3/homepage/paperIII.pdf


title: Solar Cycle Variations of p-Mode Frequencies

abstract:
  Observations show that the solar p-mode frequencies change with the solar
cycle. The horizontal-phase-velocity dependence of the relative frequency
change, scaled by mode mass, provides depth information on the perturbation in
the solar interior. We find that the smoothed scaled relative frequency change
varies along the solar cycle for horizontal phase velocities higher than a
critical value, which corresponds to a depth near the base of the convection
zone. This phenomenon suggests that the physical conditions in a region near
the base of the convection zone change with the solar cycle.


title: A photometric study of faint galaxies in the field of GRB000926

abstract:
  We present our B, V, Rc, and Ic observations of a 3.6' x 3' field centered on
the host galaxy of GRB000926 (RA(2000.0)=17h04m11s, DEC(2000.0)=+51d47'9.8'').
The observations were carried out on the 6-m Special Astrophysical Observatory
telescope using the SCORPIO instrument. The catalog of galaxies detected in
this field includes 264 objects for which the signal-to-noise ratio is larger
than 5 in each photometric band. The following limiting magnitudes in the
catalog correspond to this limitation: 26.6(B), 25.7(V), 25.8(Rc), and
24.5(Ic). The differential galaxy counts are in good agreement with previously
published CCD observations of deep fields. We estimated the photometric
redshifts for all of the cataloged objects and studied the color variations of
the galaxies with Z. For luminous spiral galaxies with M(B) < -18, we found no
evidence for any noticeable evolution of their linear sizes to Z~1.


title: Submillimetre Observations of z>6 Quasars

abstract:
  We report on submillimetre observations of three high redshift (z>6) quasars,
made using the SCUBA camera on the JCMT. Only one of the sample was detected at
850um-- SDSS J1148+5251 (z=6.43). It was also detected (>3 sigma significance)
at 450um, one of the few z>4 quasars for which this is the case. In combination
with existing millimetric data, the submm detections allow us to place limits
on the temperature of the submm-emitting dust, hence on the mass of dust to be
synthesized under the time constraint imposed by the quasar's redshift.


title: Millisecond Pulsars as Tools of Fundamental Physics

abstract:
  A new era in fundamental physics began when pulsars were discovered in 1967.
Soon it became clear that pulsars were useful tools for a wide variety of
physical and astrophysical problems. Further applications became possible with
the discovery of the first binary pulsar in 1974 and the discovery of
millisecond pulsars in 1982. Ever since pulsars have been used as precise
cosmic clocks, taking us beyond the weak-field limit of the solar-system in the
study of theories of gravity. Their contribution is crucial as no test can be
considered to be complete without probing the strong-field realm of
gravitational physics by finding and timing pulsars. This is particularly
highlighted by the discovery of the first double pulsar system in 2003. In this
review, I will explain some of the most important applications of millisecond
pulsar clocks in the study of gravity and fundamental constants.


title: The double pulsar -- A new testbed for relativistic gravity

abstract:
  The first ever double pulsar, discovered by our team a few months ago,
consists of two pulsars, one with period of 22 ms and the other with a period
of 2.7 s. This binary system with a period of only 2.4-hr provides a truly
unique laboratory for relativistic gravitational physics. In this contribution
we summarize the published results and look at the prospects of future
observations.


title:
Revealing the X-ray emission processes of old rotation-powered pulsars:
  XMM-Newton Observations of PSR B0950+08,PSR B0823+26 and PSR J2043+2740

abstract:
  We have completed part of a program to study the X-ray emission properties of
old rotation-powered pulsars with XMM-Newton in order to probe and identify the
origin of their X-radiation. The X-ray emission from these old pulsars is
largely dominated by non-thermal processes. None of the observed spectra
required adding a thermal component consisting of either a hot polar cap or
surface cooling emission to model the data. The X-ray spectrum of PSR 0950+08
is best described by a single power law of photon-index
1.93^{+0.14}_{-0.12}.Taking optical data from the VLT FORS1 into account a
broken power law model is found to describe the pulsar's broadband spectrum
from the optical to the X-ray band. Temperature upper limits for possible
contributions from a heated polar cap or the whole neutron star surface are
T_{pc} < 0.87 x10^6 K and T_s < 0.48 x 10^6 K, respectively. We also find that
the X-ray emission from PSR 0950+08 is pulsed with two peaks per rotation
period. The phase separation between the two X-ray peaks is ~144 degree. The
main radio peak and the trailing X-ray peak are almost phase aligned. The
fraction of X-ray pulsed photons is ~30%. A phase-resolved spectral analysis
confirms the non-thermal nature of the pulsed emission. Detailed pulse profile
simulations constrain the pulsar's emission geometry to be that of an almost
orthogonal rotator. The spectral emission properties observed for PSR 0823+26
are similar to those of PSR 0950+08. For PSR J2043+2740 we report the first
detection of X-ray emission. A power law spectrum, or a combination of a
thermal and a power law spectrum all yield acceptable descriptions of its X-ray
spectrum. No X-ray pulses are detected from PSR J2043+2740. A pulsed fraction
upper limit is 57%.


title:
Primordial magnetic field and non-Gaussianity of the 1-year Wilkinson
  Microwave Anisotropy Probe (WMAP) data

abstract:
  Alfven turbulence caused by statistically isotropic and homogeneous
primordial magnetic field induces correlations in the cosmic microwave
background anisotropies. The correlations are specifically between spherical
harmonic modes a_{l-1,m} and a_{l+1,m}. In this paper we approach this issue
from phase analysis of the CMB maps derived from the WMAP data sets. Using
circular statistics and return phase mapping we examine phase correlation of
\Delta l=2 for the primordial non-Gaussianity caused by the Alfven turbulence
at the epoch of recombination. Our analyses show that such specific features
from the power-law Alfven turbulence do not contribute significantly in the
phases of the maps and could not be a source of primordial non-Gaussianity of
the CMB.


title:
Evidence for a Neutron Star in the non-pulsating massive X-ray binary
  4U2206+54

abstract:
  We present an analysis of archival RXTE and BeppoSAX data of the X-ray source
4U2206+54 . For the first time, high energy data (> 30 kev) are analyzed for
this source. The data are well described by comptonization models (CompTT and
BMC) in which seed photons with temperatures between 1.1 kev and 1.5 kev are
comptonized by a hot plasma at 50 kev thereby producing a hard tail which
extends up to, at least, 100 kev. We offer a new method of identification of
neutron star systems using a temperature - luminosity relation. If a given
X-ray source is characterized by a low bolometric luminosity and a relatively
high color blackbody temperature (>1 kev) it has necessarily to be a neutron
star rather than a black hole. From these arguments it is shown that the area
of the soft photon source must be small (r ~ 1 km) and that the accretion disk,
if present, must be truncated very far from the compact object. Here we report
on the possible existence of a cyclotron line around 30 kev. The presence of a
neutron star in the system is strongly favored by the available data.


title:
The Design of Radio Telescope Array Configurations using Multiobjective
  Optimization: Imaging Performance versus Cable Length

abstract:
  The next generation of radio telescope interferometric arrays requires
careful design of the array configuration to optimize the performance of the
overall system. We have developed a framework, based on a genetic algorithm,
for rapid exploration and optimization of the objective space pertaining to
multiple objectives. We have evaluated a large space of possible designs for
27-, 60-, 100-, and 160-station arrays. The 27-station optimizations can be
compared to the well-known VLA case, and the larger array designs apply to
arrays currently under design such as LOFAR, ATA, and the SKA. In the initial
implementation of our framework we evaluate designs with respect to two
metrics, array imaging performance and the length of cable necessary to connect
the stations. Imaging performance is measured by the degree to which the
sampling of the uv plane is uniform. For the larger arrays we find that
well-known geometric designs perform well and occupy the Pareto front of
optimum solutions. For the 27-element case we find designs, combining features
of the well-known designs, that are more optimal as measured by these two
metrics. The results obtained by the multiobjective genetic optimization are
corroborated by simulated annealing, which also reveals the role of entropy in
array optimization. Our framework is general, and may be applied to other
design goals and issues, such as particular schemes for sampling the uv plane,
array robustness, and phased deployment of arrays.


title: Cosmological Magnetic Fields vs. CMB

abstract:
  I present a short review of the effects of a cosmological magnetic field on
the CMB temperature and polarization anisotropies. Various possibilities for
constraining the magnetic field amplitude are discussed.


title: Non-linear inflationary perturbations

abstract:
  We present a method by which cosmological perturbations can be quantitatively
studied in single and multi-field inflationary models beyond linear
perturbation theory. A non-linear generalization of the gauge-invariant
Sasaki-Mukhanov variables is used in a long-wavelength approximation. These
generalized variables remain invariant under time slicing changes on long
wavelengths. The equations they obey are relatively simple and can be
formulated for a number of time slicing choices. Initial conditions are set
after horizon crossing and the subsequent evolution is fully non-linear. We
briefly discuss how these methods can be implemented numerically in the study
of non-Gaussian signatures from specific inflationary models.


title: Near Infrared Intraday Variability of Mrk 421

abstract:
  We report results from our monitoring of the BL Lac object Mrk 421 in the
near-IR $J$ band. The observations, aimed at studying the intraday variability
(IDV) of the object, were carried out systematically over an extended (and
near-continuous) period of eight nights from the 1.2m Mount Abu Infrared
Telescope, India. There are limited studies for Mrk 421 in the $J$ band for
such an extended period. The observation epoch for this study (25 February - 5
March 2003) was chosen to significantly overlap other concurrent studies of Mrk
421 in the X-ray/$\gamma$-ray regions being conducted using the Rossi X-ray
timing explorer (RXTE) and the solar tower atmospheric Cherenkov effect
experiment (STACEE). Hence these results could be useful for a multi-wavelength
analysis of the variability behavior of Mrk 421. We find that Mrk 421 was quite
active during the observed period and showed significant IDV and short term
variability. A maximum variation of 0.89 magnitudes is seen over the entirety
of the observed period. Flaring activity, with typical brightness variations of
$\sim 0.4$, are also seen on several occasions. The extent of the variability
observed by us is compared with the results of other similar studies of Mrk 421
in the $J$ band.


title:
Evidence for Solar Metallicities in Massive Star-forming Galaxies at
  z>~2

abstract:
  We present results of near-IR spectroscopic measurements of 7 star-forming
galaxies at 2.1<z<2.5. Drawn from a large spectroscopic survey of galaxies
photometrically pre-selected by their U_nGR colors to lie at z~2, these
galaxies were chosen for their bright rest-frame optical luminosities
(K_s<=20.0). Most strikingly, the majority of the sample of 7 galaxies exhibit
[NII]/Ha nebular emission line ratios indicative of at least solar HII region
metallicities, at a lookback time of 10.5 Gyr. The broadband colors of the
K_s-bright sample indicate that most have been forming stars for more than a
Gyr at z~2, and have already formed stellar masses in excess of 10^11 Msun. The
descendants of these galaxies in the local universe are most likely metal-rich
and massive spiral and elliptical galaxies, while plausible progenitors for
them can be found among the population of z~3 Lyman Break Galaxies. While the
K_s-bright z~2 galaxies appear to be highly evolved systems, their large Ha
luminosities and uncorrected Ha star-formation rates of 24-60 Msun/yr indicate
that active star formation is still ongoing. The luminous UV-selected objects
presented here comprise more than half of the high-redshift (z>1.5) tails of
current K-band-selected samples such as the K20 and Gemini Deep Deep surveys.


title:
The ACS Virgo Cluster Survey III. Chandra and HST Observations of
  Low-Mass X-Ray Binaries and Globular Clusters in M87

abstract:
  The ACIS instrument on board the Chandra X-ray Observatory has been used to
carry out the first systematic study of low-mass X-ray binaries (LMXBs) in M87.
We identify 174 X-ray point-sources, of which ~150 are likely LMXBs. This LMXB
catalog is combined with deep F475W and F850LP images taken with ACS on HST to
examine the connection between LMXBs and globular clusters in M87. Of the 1688
globular clusters in our catalog, f_X = 3.6 +- 0.5% contain a LMXB and we find
that the metal-rich clusters are 3 +- 1 times more likely to harbor a LMXB than
their metal-poor counterparts. In agreement with previous findings for other
galaxies, we find that brighter, more metal-rich clusters are more likely to
contain a LMXB. For the first time, however, we are able to demonstrate that
the probability, p_X, that a given cluster will contain a LMXB depends
sensitively on the dynamical properties of the host cluster. Specifically, we
use the HST images to measure the half-light radius, concentration index and
central density, \rho_0, for each globular, and define a parameter, \Gamma,
which is related to the tidal capture and binary-neutron star exchange rate.
Our preferred form for p_X is then p_X \propto \Gamma \rho_0^{-0.42\pm0.11}
(Z/Z_{\odot})^{0.33\pm0.1}. We argue that if the form of p_X is determined by
dynamical processes, then the observed metallicity dependence is a consequence
of an increased number of neutron stars per unit mass in metal-rich globular
clusters. Finally, we find no compelling evidence for a break in the luminosity
distribution of resolved X-ray point sources. Instead, the LMXB luminosity
function is well described by a power law with an upper cutoff at L_X ~ 10^39
erg/s. (abridged)


title: The Effect of Gas Cooling on the Shapes of Dark Matter Halos

abstract:
  We analyze the effect of dissipation on the shapes of dark matter (DM) halos
using high-resolution cosmological gasdynamics simulations of clusters and
galaxies in the LCDM cosmology. We find that halos formed in simulations with
gas cooling are significantly more spherical than corresponding halos formed in
adiabatic simulations. Gas cooling results in an average increase of the
principle axis ratios of halos by ~ 0.2-0.4 in the inner regions. The
systematic difference decreases slowly with radius but persists almost to the
virial radius. We argue that the differences in simulations with and without
cooling arise both during periods of quiescent evolution, when gas cools and
condenses toward the center, and during major mergers. We perform a series of
high-resolution N-body simulations to study the shapes of remnants in major
mergers of DM halos and halos with embedded stellar disks. In the DM halo-only
mergers, the shape of the remnants depends only on the orbital angular momentum
of the encounter and not on the internal structure of the halos. However,
significant shape changes in the DM distribution may result if stellar disks
are included. In this case the shape of the DM halos is correlated with the
morphology of the stellar remnants.


title:
High Resolution Mid-Infrared Observations of Low-Luminosity AGN with the
  Keck Telescope and LWS

abstract:
  We present high-resolution Keck LWS SiC filter (10.5-12.9 micron) mid-IR
(MIR) images and photometry of a sample of nearby LLAGN. All MIR images show
extended emission on small scales (e.g. 90% maximum widths 18 - 106 pc) deep
within the nucleus. Because the profile of this small-scale emission is
inconsistent with the near-IR stellar emission profile, we conclude the MIR
emission is not from the stellar population. Because strong starburst emission
is not reported for our objects, we eliminate this origin as well, and conclude
that the extended component of the MIR emission is most likely due to a warm
dust structure deep in the nucleus, consistent with the gross details of a
Unified Model Torus.
  Because MIR and X-ray flux measurements are very insensitive to the effects
of pure dust extinction, the ratio of MIR and X emission can be used as a
discriminator of emission processes that is insensitive to dust extinction. X
and MIR emission are known to be correlated in quasars and Seyfert galaxies.
Our LLAGN objects follow this correlation with small scatter down to extremely
low luminosity, suggesting that the same continuum emission mechanisms are
present in LLAGN as in Seyferts and quasars. This result suggests that weak UV
emission (relative to other bands) in LLAGN compared to Seyferts and quasars
could be due to dust extinction; it then follows that modifications to standard
AGN continuum emission models for LLAGN (e.g. ADAF accretion) are not required.


title:
Profile variability of the H-alpha and H-beta broad emission lines in
  NGC5548

abstract:
  Between 1996 and 2002, we have carried out a spectral monitoring program for
the Seyfert galaxy NGC 5548. High quality spectra (S/N>50), covering the
spectral range (4000-7500)AA were obtained with the 6 m and 1 m telescopes of
SAO (Russia) and with the 2.1 m telescope GHO (Mexico). We found that both the
flux in the lines and the continuum gradually decreased, reaching minimum
values during May-June 2002. The mean, rms, and the averaged over years,
observed and difference line profiles of H-alpha and H-beta reveal the double
peaked structure at the radial velocity ~+-1000km/s. The relative intensity of
these peaks changes with time. During 1996, the red peak was the brightest,
while in 1998 - 2002, the blue peak became the brighter one. In 2000-2002 a
distinct third peak appeared in the red wing of H-alpha and H-beta line
profiles. The radial velocity of this feature decreased between 2000 and 2002
from ~+2500 km/s to ~+2000 km/s. The fluxes of the various parts of the line
profiles are well correlated with each other and also with the continuum flux.
Shape changes of the different parts of the broad line are not correlated with
continuum variations and, apparently, are not related to reverberation effects.
Changes of the integral Balmer decrement are, on average, anticorrelated with
the continuum flux variations. This is probably due to an increasing role of
collisional excitation as the ionizing flux decreases. Our results favor the
formation of the broad Balmer lines in a turbulent accretion disc with large
and moving "optically thick" inhomogeneities, capable of reprocessing the
central source continuum.


title: Al(26) Studies with INTEGRAL's Spectrometer SPI

abstract:
  Al(26) radioactivity traces recent nucleosynthesis throughout the Galaxy, and
is known to be produced in massive stars and novae. The map from its decay
gamma-ray line suggests massive stars to dominate, but high-resolution line
spectroscopy is expected to supplement imaging of Al(26) source regions and
thus to help decide about the Al(26) injection process and interstellar
environment, hence about the specific massive-star subgroup and phase which
produces interstellar Al(26). The INTEGRAL Spectrometer SPI has observed
Galactic Al(26) radioactivity in its 1809 keV gamma-ray line during its first
inner-Galaxy survey. Instrumental background lines make analysis difficult;
yet, a clear signal from the inner Galaxy agrees with expectations. In
particular, SPI has constrained the line width to exclude previously-reported
line broadenings corresponding to velocities >500 km/s. The
signal-to-background ratio of percent implies that detector response and
background modeling need to be fine-tuned to eventually enable line shape
deconvolution in order to extract source location information along the line of
sight.


title:
A large stellar evolution database for population synthesis studies. I.
  Scaled solar models and isochrones

abstract:
  We present a large and updated stellar evolution database for low-,
intermediate- and high-mass stars in a wide metallicity range, suitable for
studying Galactic and extragalactic simple and composite stellar populations
using population synthesis techniques. The stellar mass range is between
\sim0.5Mo and 10Mo with a fine mass spacing. The metallicity [Fe/H] comprises
10 values ranging from -2.27 to 0.40, with a scaled solar metal distribution.
The initial He mass fraction ranges from Y=0.245, for the more metal-poor
composition, up to 0.303 for the more metal-rich one, with Delta Y/Delta Z\sim
1.4. For each adopted chemical composition, the evolutionary models have been
computed without and with overshooting from the Schwarzschild boundary of the
convective cores during the central H-burning phase. The whole set of
evolutionary models can be used to compute isochrones in a wide age range, from
\sim30 Myr to \sim15Gyr. Both evolutionary tracks and isochrones are available
in several observational planes, employing updated set of bolometric
corrections and color-Te relations computed for this project. The number of
points along the models and the resulting isochrones is selected in such a way
that interpolation for intermediate metallicities not contained in the grid is
straightforward. We compare our isochrones with results from different stellar
evolution databases and perform some empirical tests for the reliability of our
models. Since this work is devoted to scaled solar compositions, we focus our
attention on the Galactic disk populations, employing multicolor photometry of
unevolved field MS stars with precise Hipparcos parallaxes, well-studied open
clusters and one eclipsing binary system with precise measurements of masses,
radii and [Fe/H] of both components.


title:
The Highly Relativistic Binary Pulsar PSR J0737-3039A: Discovery and
  Implications

abstract:
  PSR J0737-3039A is a millisecond pulsar with a spin period of 22.7 ms
included in a double-neutron star system with an orbital period of 2.4 hrs. Its
companion has also been detected as a radio pulsar, making this binary the
first known double-pulsar system. Its discovery has important implications for
relativistic gravity tests, gravitational wave detection and plasma physics.
Here we will shortly describe the discovery of the first pulsar in this unique
system and present the first results obtained by follow-up studies.


title: PAHs in Circumstellar Disks around Herbig Ae/Be stars

abstract:
  We investigate the presence and properties of PAHs on the surface of
circumstellar disks around Herbig Ae/Be stars by comparing the predictions of
disk models with observations. We present results of a radiation transfer code
for disks heated by the central star, in hydrostatic equilibrium in the
vertical direction (flared disks). The dust is a mixture of large grains in
thermal equilibrium, transiently heated small grains and PAHs. Special
attention is given to the influence of the stellar, disk and PAHs properties on
the strength of the PAH emission lines and their spatial distribution. The
models predict an infrared SED showing PAH features at 3.3, 6.2, 7.7, and 11.3
\um clearly visible above the continuum, and with some of them very strong. The
PAH emission, spatially extended, comes mostly from the outer disk region
($R\sim$100 AU) while the continuum emission at similar wavelengths, mostly due
to warm large grains, is confined to the innermost disk regions ($R\sim$few
AU). We compare the model results to infrared observations from ISO and
ground-based telescopes of some thirty Herbig Ae/Be stars. Most of the observed
PAH features in objects with spectral type later than B9 are well described by
our disk models and we discuss in some detail the PAH characteristics one can
derive from the existing data. Objects with strong radiation field (generally
earlier than about B9) have the 3.3 $\mu$m feature (often the only one
observed) much weaker than predicted, and we discuss possible explanations
(dissipation of the disk, photoevaporation or modification of the PAH
properties).


title: The Minimal Cooling of Neutron Stars

abstract:
  A general overview of the main physical processes driving the cooling of an
isolated neutron star is presented. Among the most important ones are the
various possible neutrino emission processes and the occurrence of baryon
pairing. Special emphasis is also put on the importance of the chemical
composition of the upper layers of the star. A detailed analysis of a Minimal
Scenario, which explicitly postulates that no ``exotic'' form of matter be
present, is summarized and compared with presently available observational
data. No striking incompatibility of the data with the predictions of the
Minimal Scenario is found. Nevertheless, two, possibly three, conspicuous stars
are identified which may, when better data are available, constitute strong
astrophysical evidence for the occurrence of a new state of matter at high
density.


title:
Kinematic and structural analysis of the Minispiral in the Galactic
  Center from BEAR spectro-imagery

abstract:
  Integral field spectroscopy of the inner region of the Galactic Center, over
a field of roughly 40"x40" was obtained at 2.06 microns (He I) and 2.16 microns
(Brackett-gamma) using BEAR, an imaging Fourier Transform Spectrometer, at
spectral resolutions respectively of 52.9 km/s and 21.3 km/s, and a spatial
resolution of ~0.5". The analysis of the data was focused on the kinematics of
the gas flows, traditionally called the "Minispiral", concentrated in the
neighborhood of the central black hole, Sgr A*. From the decomposition into
several velocity components of the line profile extracted at each point of the
field, velocity features were identified. Nine distinguishable structures are
described: the standard Northern Arm, Eastern Arm, Bar, Western Arc, and five
additional, coherently-moving patches of gas. From this analysis, the Northern
Arm appears not limited, as usually thought, to the bright, narrow North-South
lane seen on intensity images, but it instead consists of a weak, continuous,
triangular-shaped surface, drawn out into a narrow stream in the vicinity of
Sgr A* where it shows a strong velocity gradient, and a bright western rim. The
Eastern Arm is split into three components. We also report extinction of some
interstellar structures by others, providing information on their relative
position along the line of sight. A system of Keplerian orbits can be fitted to
most of the Northern Arm, and the bright rim of this feature can be interpreted
in terms of line-of-sight orbit crowding caused by the warping of the flowing
surface at the western edge facing Sgr A*. The question of the origin of the
ionized gas is addressed and a discussion of the lifetime of these features is
presented.


title:
The Geneva-Copenhagen survey of the Solar neighbourhood: Ages,
  metallicities, and kinematic properties of 14,000 F and G dwarfs

abstract:
  We present and discuss new determinations of metallicity, rotation, age,
kinematics, and Galactic orbits for a complete, magnitude-limited, and
kinematically unbiased sample of 16,682 nearby F and G dwarf stars. Our 63,000
new, accurate radial-velocity observations for nearly 13,500 stars allow
identification of most of the binary stars in the sample and, together with
published data complete the kinematic information for 14,139 stars. A major
effort has been devoted to the determination of new isochrone ages for all
stars for which this is possible. Particular attention has been given to a
realistic treatment of statistical biases and error estimates, as standard
techniques tend to underestimate these effects and introduce spurious features
in the age distributions. We demonstrate, however, how strong observational and
theoretical biases cause the distribution of the observed ages to be very
different from that of the true age distribution of the sample. Our first
results confirm the lack of metal-poor G dwarfs relative to closed-box model
predictions (the ``G dwarf problem''), the existence of radial metallicity
gradients in the disk, the small change in mean metallicity of the thin disk
since its formation and the substantial scatter in metallicity at all ages, and
the continuing kinematic heating of the thin disk with an efficiency consistent
with that expected for a combination of spiral arms and giant molecular clouds.
Distinct features in the distribution of the V component of the space motion
are extended in age and metallicity, corresponding to the effects of stochastic
spiral waves rather than classical moving groups, and may complicate the
identification of thick-disk stars from kinematic criteria. (abridged)


title: Discovery of Optical Bursts from MS1603.6+2600 = UW CrB

abstract:
  We report the discovery of several optical burst-like events from the
low-mass X-ray binary MS1603.6+2600 (UW CrB). The events last for a few tens of
seconds, exhibit a very fast rise and slow decay, and involve optical
brightening of a factor of 2-3. The flares appear distinct from the lower level
flickering and instead strongly resemble reprocessed type-I X-ray bursts as
seen in a number of other neutron star low-mass X-ray binaries. In conjunction
with the previously reported candidate X-ray burst, these confirm that the
compact object in UW CrB is a neutron star. We examine the optical burst
brightness and recurrence times and discuss how the nature of the system can be
constrained. We conclude that the source is most likely an accretion disk
corona source at an intermediate distance, rather than a nearby quiescent
system or very distant dipper.


title: Sources for Gravitational Fields and Cosmology

abstract:
  Analysis of the gravitational source for the Schwarzschild metric indicates
that the time and the radial components of the energy momentum tensor are
equal. Imposing such a condition on cosmology, we propose a cosmological model
that is a modification of the Friedman-Robertson-Walker (FRW) universe. An
accelerating universe emerges as a natural consequence of this ansatz.


title:
A bound on galactic mass loss rates obtaind from globular cluster
  dynamics

abstract:
  Using tidal disruption of globular clusters by the galactic center, we put
limits on the total mass ever enclosed into orbits of observed globular
clusters. Under the assumption that the rate of mass loss from the Galaxy is
steady, we then deduce a bound on this rate. In particular this bound can be
used to constrain the galactic gravitational wave luminosity.


title: High Speed Photometry of SDSS J013701.06-091234.9

abstract:
  We present high speed photometry of the Sloan Digital Sky Survey cataclysmic
variable SDSS J013701.06-091234.9 in quiescence and during its 2003 December
superoutburst. The orbital modulation at 79.71\pm0.01 min is double humped; the
superhump period is 81.702\pm0.007 min. Towards the end of the outburst late
superhumps with a period of 81.29\pm0.01 min were observed. We argue that this
is a system of very low mass transfer rate, and that it probably has a long
outburst interval.


title: CHANDRA Detection of the AM CVn binary ES Cet (KUV 01584-0939)

abstract:
  We report on CHANDRA ACIS observations of the ultracompact AM CVn binary ES
Cet. This object has a 10.3 minute binary period and is the most compact of the
confirmed AM CVn systems. We have, for the first time, unambiguously detected
the X-ray counterpart to ES Cet. In a 20 ksec ACIS-S image a point-like X-ray
source is found within 1'' of the catalogued optical position. The mean
countrate in ACIS-S is 0.013 cts/s, and there is no strong evidence for
variability. We extract the first X-ray spectrum from ES Cet, and find that it
is not well described by simple continuum models. We find suggestive evidence
for discrete spectral components at about 470 and 890 eV, that can be modelled
as gaussian emission lines. In comparison with recent X-ray detections of
nitrogen and neon in another AM CVn system (GP Com), it appears possible that
these features may represent emission lines from these same elements; however,
deeper spectroscopy will be required to confirm this.


title: Scientific Performance of the ISDC Quick Look Analysis

abstract:
  The INTEGRAL Science Data Centre (ISDC) routinely monitors the Near Real Time
data (NRT) from the INTEGRAL satellite. A first scientific analysis is made in
order to check for the detection of new, transient or highly variable sources
in the data. Of primary importance for this work is the Interactive Quick Look
Analysis (IQLA), which produces JEM-X and ISGRI images and monitors them for
interesting astrophysical events


title: Large-Scale Correlations in the Lyman-alpha Forest at z = 3-4

abstract:
  We present a study of the spatial coherence of the intergalactic medium
toward two pairs of high-redshift quasars with moderate angular separations
observed with Keck/ESI, Q1422+2309A/Q1424+2255 (z_em = 3.63, theta = 39") and
Q1439-0034A/B (z_em = 4.25, theta = 33"). The crosscorrelation of transmitted
flux in the Lyman-alpha forest shows a 5-7 sigma peak at zero velocity lag for
both pairs. This strongly suggests that at least some of the absorbing
structures span the 230-300/h_70 proper kpc transverse separation between
sightlines. We also statistically examine the similarity between paired spectra
as a function of transmitted flux, a measure which may be useful for comparison
with numerical simulations. In investigating the dependence of the correlation
functions on spectral characteristics, we find that photon noise has little
impact for S/N >~ 10 per resolution element. However, the agreement between the
autocorrelation along the line sight and the crosscorrelation between
sightlines, a potential test of cosmological geometry, depends significantly on
instrumental resolution. Finally, we present an inventory of metal lines. These
include a a pair of strong C IV systems at z ~ 3.4 appearing only toward
Q1439B, and a Mg II + Fe II system present toward Q1439 A and B at z = 1.68.


title:
Revision of the properties of the GRS 1915+105 jets: Clues from the
  large-scale structure

abstract:
  The jets of GRS 1915+105 carry a considerable energy away from the central
source into the ISM. The similarity of the jets of this source and jets in
radio galaxies or radio-loud quasars suggests that we should detect
large-scale, synchrotron emitting radio structures surrounding GRS 1915+105.
However, these large structures have not been found. We show that by adapting a
model for the radio lobes of extragalatic jet sources we predict a radio
surface brightness of the equivalent structures of GRS 1915+105 below the
current detection limits. The model uses an energy transport rate of the jets
averaged over the jet lifetime. This transport rate is found to be considerably
lower than the power of the jets during the rare major ejection events. Thus
the lobes contain less energy than would be inferred from these events and
produce a lower radio luminosity. The model also predicts a lifetime of the
jets of order $10^6$ years and a gas density of the ISM in the vicinity of GRS
1915+105 of $\sim 150$ cm$^{-3}$. The impact sites of the jets are identified
with two {\sc iras} regions with a flat radio spectrum located on either side
of GRS 1915+105. Observations of molecular lines and dust emission from these
objects are consistent with our interpretation. Distance estimates for the {\sc
iras} regions give 6.5 kpc and our model implies that this is also the distance
to GRS 1915+105. This low distance estimate in combination with the observed
motions of jet ejections on small scales yields a jet velocity of about 0.7 c
and an angle of $53^{\circ}$ of the jets to our line of sight.


title: Contribution of point sources to the soft gamma-ray Galactic emission

abstract:
  The nature of the soft gamma-ray (20-200 keV) Galactic emission has been a
matter of debate for a long time. Previous experiments have tried to separate
the point source contribution from the real interstellar emission, but with a
rather poor spatial resolution, they concluded that the interstellar emission
could be a large fraction of the total Galactic emission. INTEGRAL, having both
high resolution and high sensitivity, is well suited to reassess more precisely
this problem. Using the INTEGRAL core program Galactic Center Deep Exposure
(GCDE), we estimate the contribution of detected point sources to the total
Galactic flux.


title:
The Oxford-Dartmouth Thirty Degree Survey I: Observations and
  Calibration of a Wide-Field Multi-Band Survey

abstract:
  The Oxford Dartmouth Thirty Degree Survey (ODTS) is a deep, wide, multi-band
imaging survey designed to cover a total of 30 square degrees in BVRi'Z, with a
subset of U and K band data, in four separate fields of 5-10 deg^2 centred at
00:18:24 +34:52, 09:09:45 +40:50, 13:40:00 +02:30 and 16:39:30 +45:24.
Observations have been made using the Wide Field Camera on the 2.5-m Isaac
Newton Telescope in La Palma to average limiting depths (5 sigma Vega, aperture
magnitudes) of U=24.8, B=25.6, V=25.0, R=24.6, and i'=23.5, with observations
taken in ideal conditions reaching the target depths of U=25.3, B=26.2, V=25.7,
R=25.4, and i'=24.6. The INT Z band data was found to be severely effected by
fringing and, consequently, is now being obtained at the MDM observatory in
Arizona. A complementary K-band survey has also been carried out at MDM,
reaching an average depth of K_{5\sigma}~18.5. At present, approximately 23
deg^2 of the ODTS have been observed, with 3.5 deg^2 of the K band survey
completed. This paper details the survey goals, field selection, observation
strategy and data reduction procedure, focusing on the photometric calibration
and catalogue construction. Preliminary photometric redshifts have been
obtained for a subsample of the objects with R <= 23. These results are
presented alongside a brief description of the photometric redshift
determination technique used. The median redshift of the survey is estimated to
be z~0.7 from a combination of the ODTS photometric redshifts and comparison
with the redshift distributions of other surveys. Finally, galaxy number counts
for the ODTS are presented which are found to be in excellent agreement with
previous studies.


title: Simulations of Turbulent Thermonuclear Burning in Type Ia Supernovae

abstract:
  Type Ia supernovae have recently received considerable attention because it
appears that they can be used as "standard candles" to measure cosmic distances
out to billions of light years away from us. Observations of type Ia supernovae
seem to indicate that we are living in a universe that started to accelerate
its expansion when it was about half its present age. These conclusions rest
primarily on phenomenological models which, however, lack proper theoretical
understanding, mainly because the explosion process, initiated by thermonuclear
fusion of carbon and oxygen into heavier elements, is difficult to simulate
even on supercomputers. Here, we investigate a new way of modeling turbulent
thermonuclear deflagration fronts in white dwarfs undergoing a type Ia
supernova explosion. Our approach is based on a level set method which treats
the front as a mathematical discontinuity and allows for full coupling between
the front geometry and the flow field. New results of the method applied to the
problem of type Ia supernovae are obtained. It is shown that in 2-D with high
spatial resolution and a physically motivated subgrid scale model for the
nuclear flames numerically "converged" results can be obtained, but for most
initial conditions the stars do not explode. In contrast, simulations in 3-D,
do give the desired explosions and many of their properties, such as the
explosion energies, lightcurves and nucleosynthesis products, are in very good
agreement with observed type Ia supernovae.


title: Photoionization Modeling and the K Lines of Iron

abstract:
  We calculate the efficiency of iron K line emission and iron K absorption in
photoionized models using a new set of atomic data. These data are more
comprehensive than those previously applied to the modeling of iron K lines
from photoionized gases, and allow us to systematically examine the behavior of
the properties of line emission and absorption as a function of the ionization
parameter, density and column density of model constant density clouds. We show
that, for example, the net fluorescence yield for the highly charged ions is
sensitive to the level population distribution produced by photoionization, and
these yields are generally smaller than those predicted assuming the population
is according to statistical weight. We demonstrate that the effects of the many
strongly damped resonances below the K ionization thresholds conspire to smear
the edge, thereby potentially affecting the astrophysical interpretation of
absorption features in the 7-9 keV energy band. We show that the centroid of
the ensemble of K$\alpha$ lines, the K$\beta$ energy, and the ratio of the
K$\alpha_1$ to K$\alpha_2$ components are all diagnostics of the ionization
parameter of our model slabs


title: Type Ia supernova rate at a redshift of ~ 0.1

abstract:
  We present the type Ia rate measurement based on two EROS supernova search
campaigns (in 1999 and 2000). Sixteen supernovae identified as type Ia were
discovered. The measurement of the detection efficiency, using a Monte Carlo
simulation, provides the type Ia supernova explosion rate at a redshift ~ 0.13.
The result is $0.125^{+0.044+0.028}_{-0.034-0.028} h_{70}^2$ SNu where 1 SNu =
1 SN / $10^{10} L_{sun}^B$ / century. This value is compatible with the
previous EROS measurement (Hardin et al. 2000), done with a much smaller
sample, at a similar redshift. Comparison with other values at different
redshifts suggests an evolution of the type Ia supernova rate.


title: X-ray emission from the old pulsar B0950+08

abstract:
  We present the timing and spectral analyses of theXMM-newton data on the
17-Myr-old, nearby radio pulsar B0950+08. This observation revealed pulsations
of the X-ray flux of the pulsar at its radio period. The pulse shape and pulsed
fraction are apparently different at lower and higher energies of the observed
0.2-10 keV energy range, which suggests that the radiation cannot be explained
by a single emission mechanism. The X-ray spectrum of the pulsar can be fitted
with a power-law model with a photon index about 1.75 and an (isotropic)
luminosity about 9.8e29 erg/s in the 0.2-10 keV. Better fits are obtained with
two-component, power-law plus thermal, models with index of 1.30 and 9.7e29
erg/s for the power-law component that presumably originates from the pulsar's
magnetosphere. The thermal component, dominating at E>0.7 keV, can be
interpreted as radiation from heated polar caps on the neutron star surface
covered with a hydrogen atmosphere. The inferred effective temperature, radius,
and bolometric luminosity of the polar caps are about 1 MK, 250 m, and 3e29
erg/s. Optical through X-ray nonthermal spectrum of the pulsar can be described
as a single power-law with index 1.3-1.4 for the two-component X-ray fit. The
ratio of the nonthermal X-ray (1-10 keV) luminosity to the nonthermal optical
(4000-9000 \AA) luminosity is within the range of 1e2-1e3 observed for younger
pulsars, which suggests that the magnetospheric X-ray and optical emissions are
powered by the same mechanism in all pulsars. An upper limit on the temperature
of the bulk of the neutron star surface, inferred from the optical and X-ray
data, is about 0.15 MK. We also analyze X-ray observations of several other old
pulsars, B2224+65, J2043+2740, B0628-28, B1813-36, B1929+10, and B0823+26.


title: XMM-Newton observations of three high-redshift radio galaxies

abstract:
  We present the results of XMM-Newton observations of three high-redshift
powerful radio galaxies 3C 184, 3C 292 and 3C 322. Although none of the sources
lies in as rich an X-ray-emitting environment as is seen for some powerful
radio galaxies at low redshift, the environments provide sufficient pressure to
confine the radio lobes. The weak gas emission is particularly interesting for
3C 184, where a gravitational arc is seen, suggesting the presence of a massive
cluster. Here Chandra data complement the XMM-Newton measurements by spatially
separating X-rays from the extended atmosphere, the nucleus and the small-scale
radio source. For 3C 292 the X-ray-emitting gas has a temperature of ~2 keV and
luminosity of 6.5E43 erg/s, characteristic of a poor cluster. In all three
cases, structures where the magnetic-field strength can be estimated through
combining measurements of radio-synchrotron and inverse-Compton-X-ray emission,
are consistent with being in a state of minimum total energy. 3C 184 and 3C 292
(and possibly 3C 322) have a heavily absorbed component of nuclear emission of
N_H ~ $ few 10^{23} cm^{-2}.


title: Early Stages of the GRB Explosion

abstract:
  Physics of GRB blast waves is discussed with a focus on two effects: (1) pair
creation in the external medium by the gamma-ray front and (2) decay of
neutrons ahead of the decelerating blast wave. Both effects impact the
afterglow mechanism at radii up to 10^{17}cm.


title: Planet Formation by Coagulation: A Focus on Uranus and Neptune

abstract:
  Planets form in the circumstellar disks of young stars. We review the basic
physical processes by which solid bodies accrete each other and alter each
others' random velocities, and we provide order-of-magnitude derivations for
the rates of these processes. We discuss and exercise the two-groups
approximation, a simple yet powerful technique for solving the evolution
equations for protoplanet growth. We describe orderly, runaway, neutral, and
oligarchic growth. We also delineate the conditions under which each occurs. We
refute a popular misconception by showing that the outer planets formed quickly
by accreting small bodies. Then we address the final stages of planet
formation. Oligarchy ends when the surface density of the oligarchs becomes
comparable to that of the small bodies. Dynamical friction is no longer able to
balance viscous stirring and the oligarchs' random velocities increase. In the
inner-planet system, oligarchs collide and coalesce. In the outer-planet
system, some of the oligarchs are ejected. In both the inner- and outer-planet
systems, this stage ends once the number of big bodies has been reduced to the
point that their mutual interactions no longer produce large-scale chaos.
Subsequently, dynamical friction by the residual small bodies circularizes and
flattens their orbits. The final stage of planet formation involves the clean
up of the residual small bodies. Clean up has been poorly explored.


title:
Search for Small-Mass Black Hole Dark Matter with Space-Based
  Gravitational Wave Detectors

abstract:
  The high sensitivity of upcoming space-based gravitational wave detectors
suggests the possibility that if halo dark matter were composed of primordial
black holes (PBHs) with mass between $10^{16}$ g and 10$^{20}$ g, the
gravitational interaction with detector test masses will lead to a detectable
pulse-like signal during the fly-by. For an improved version of the Laser
Interferometer Space Antenna with a reduced acceleration noise at the low-end
of its frequency spectrum, we find an event rate, with signal-to-noise ratios
greater than 5, of $\sim$ a few per decade involving black holes of mass $\sim$
10$^{17}$ g. The detection rate improves significantly for second generation
space based interferometers that are currently envisioned, though these events
must be distinguished from those involving perturbations due to near-Earth
asteroids. While the presence of primordial black holes below a mass of $\sim$
10$^{16}$ g is now constrained based on the radiation released during their
evaporation, the gravitational wave detectors will extend the study of PBHs to
a several orders of magnitude higher masses.


title: Prospects for the Detection of Earth-Mass Planets

abstract:
  We compare potential state-of-the-art experiments for detecting Earth-mass
planets around main-sequence stars using radial velocities, transits,
astrometry, and microlensing. For conventionally-discussed signal-to-noise
ratio (S/N) thresholds, S/N ~ 8, the last three methods are roughly comparable
in terms of both the total number of planets detected and the mass distribution
of their host stars. However we argue that S/N ~ 25 is a more conservative and
realistic S/N threshold. We show analytically and numerically that the decline
in the number of detections as a function of S/N is very steep for radial
velocities, transits, and astrometry, such that the number of expected
detections at S/N ~ 25 is more than an order-of-magnitude smaller than at
conventional S/N thresholds. Indeed, unless Earth-mass planets are very common
or are packed much closer to their parent stars than in the solar system,
future searches using these methods (as they are currently planned) may not
yield any reliable Earth-mass planet detections. On the other hand,
microlensing has a much shallower S/N slope than the other techniques and so
has much greater sensitivity at realistic S/N thresholds. We show that even if
all stars have Earth-mass planets at periods of one year (and adopting other
optimistic assumptions as well), the combined yield of all four techniques
would be the detection of only about five such planets at S/N ~ 25.


title: Search for Neutrino-Induced Cascades with AMANDA

abstract:
  We report on a search for electro-magnetic and/or hadronic showers (cascades)
induced by high energy neutrinos in the data collected with the AMANDA II
detector during the year 2000. The observed event rates are consistent with the
expectations for atmospheric neutrinos and muons. We place upper limits on a
diffuse flux of extraterrestrial electron, tau and muon neutrinos. A flux of
neutrinos with a spectrum $\Phi \propto E^{-2}$ which consists of an equal mix
of all flavors, is limited to $E^2 \Phi(E)=8.6 x 10^{-7} GeV/(cm^{2} s sr)$ at
a 90% confidence level for a neutrino energy range 50 TeV to 5 PeV. We present
bounds for specific extraterrestrial neutrino flux predictions. Several of
these models are ruled out.


title: Possible Detection of Cosmological Reionization Sources

abstract:
  We compare the available catalogs of $z\approx6$ galaxies in the Hubble
Ultra-Deep Field (UDF) and in the Great Observatories Origins Deep Survey
(GOODS) with the expected properties of the sources of cosmological
reionization from our previous theoretical study. Our approach is based on the
mean surface brightness of the sources required for reionization and depends on
relatively few undetermined parameters. We find that the observed mean surface
brightness of galaxies at $z \approx 6$ is sufficient for reionization,
provided that the sources are composed of hot metal-free or metal-poor stars,
regardless of whether reionization occurs over a short or long interval of
redshift. The broad agreement between the new observations and our predictions
suggests that we may have detected the sources responsible for some or even all
of the reionization of hydrogen.


title: A Parallel TreePM Code

abstract:
  We present an algorithm for parallelising the TreePM code. We use both
functional and domain decompositions. Functional decomposition is used to
separate the computation of long range and short range forces, as well as the
task of coordinating communications between different components. Short range
force calculation is time consuming and benefits from the use of domain
decomposition. We have tested the code on a Linux cluster. We get a speedup of
31.4 for 128^3 particle simulation on 33 processors; speedup being better for
larger simulations. The time taken for one time step per particle is 6.5 micro
seconds for a 256^3 particle simulation on 65 processors, thus a simulation
that runs for 4000 time steps takes 5 days on this cluster.


title:
A Subaru Search for Ly-alpha Blobs in and around the Proto-cluster
  Region at Redshift z=3.1

abstract:
  We report the properties of the 35 robust candidates of Ly-alpha blobs
(LABs), which are larger than 16 arcsec^2 in isophotal area and brighter than
0.7 x 10^-16 ergs s^-1 cm^-2, searched in and around the proto-cluster region
at redshift z=3.1 discovered by Steidel et al. in the SSA22 field, based on
wide-field (31'x23') and deep narrow-band (NB497; 4977/77) and broad-band (B,V,
and R) images taken with the prime-focus camera on the Subaru telescope. The
two previously known giant LABs are the most luminous and the largest ones in
our survey volume of 1.3 x 10^5 Mpc^3. We revealed the internal structures of
the two giant LABs and discovered some bubble-like features, which suggest that
intensive starburst and galactic superwind phenomena occurred in these objects
in the past. The rest 33 LABs have isophotal area of about 16-78 arcsec^2 and
flux of 0.7-7 x 10^-16 ergs s^-1 cm^-2. These 35 LABs show a continuous
distribution of isophotal area and emission line flux. The distributions of
average surface brightness and morphology are widespread from relatively
compact high surface brightness objects to very diffuse low surface brightness
ones. The physical origins of these LABs may be (i) photo-ionization by massive
stars, or active galactic nuclei, or (ii) cooling radiation from
gravitationally heated gas, or (iii) shock heating by starburst driven galactic
superwind. One third of them are apparently not associated with ultra-violet
continuum sources that are bright enough to produce Ly-alpha emission, assuming
a Salpeter initial mass function. The 90% of these LABs are located inside the
high surface density region of the 283 relatively compact and strong Ly-alpha
emitters selected in our previous study. This suggests that these LABs may be
the phenomena related to dense environment at high redshift.


title:
A Subaru Search for Lyman-Alpha Emitters at z=5.8 with an
  Intermediate-Band Filter

abstract:
  We present the results of a survey for Ly-alpha emitters at z ~ 5.8 using a
new intermediate-band filter centered at lambda_c = 8275 AA with
Delta-lambda_FWHM = 340 AA (i.e., the spectroscopic resolution is R ~ 23) with
a combination with a traditional narrow-band centered at lambda_c = 8150 AA
with
  Delta-lambda_FWHM = 120 AA (R ~ 68). Our observations were made with use of
the Subaru Prime Focus Camera, Suprime-Cam, on the 8.2 m Subaru telescope in a
sky area surrounding the high redshift quasar, SDSSp J104433.04-012522.2 at
z=5.74, covering an effective sky area with ~ 720 arcmin^2. In this survey, we
have found four Ly-alpha-emitter candidates from the intermediate-band image (z
\~ 5.8 with Delta z ~ 0.3). Combined with our previous results based on the
NB816 imaging, we discuss the star formation activity in galaxies between z ~
5.7 and z ~ 5.9.


title:
Clusters outskirts at X-ray wavelengths: current status and future
  prospects

abstract:
  A solid observational characterization of cluster regions around the virial
radius would allow us to improve considerably our understanding of the physics
of galaxy clusters as a whole: sadly current and planned experiments will not
allow us to study these regions. Unbeknownst to most but not all, the
development of an experiment sensitive to cluster outer regions could be
achieved with currently available technology, with no need for breakthroughs.
Amongst the major factors that will decide whether and when such an experiment
will be flown are the awareness of the cluster community of the importance of
such a mission and its determination in supporting it.


title: The Coma Cluster at gamma-ray energies: multifrequency constraints

abstract:
  The Coma cluster exhibits evidence for a high-energetic non-thermal particle
population. At frequencies >1 GHz recent radio halo observations confirm a
significant spectral steepening of the volume-integrated emission. We calculate
the volume-averaged high-energy spectrum due to inverse Compton scattering off
the CMB radiation field and non-thermal bremsstrahlung according to an
exponential cutoff in the electron spectrum as deduced from the radio
observations. The synchrotron radiation from secondary pairs, created from the
decay of charged mesons produced in hadronic pp-interactions, is found to set
significant constraints on the energy content of relativistic hadrons in Coma.
This limits the maximum flux at high energies. Our findings support a low ratio
of relativistic hadron to thermal energy density. Predictions for Coma's high
energy emission are discussed in the light of current and expected abilities of
upcoming gamma-ray instruments.


title:
XMM Cluster Survey: X-ray source identification using the Sloan Digital
  Sky Survey

abstract:
  [ABRIDGED] The XMM Cluster Survey (XCS) is predicted to detect thousands of
clusters observed serendipitously in XMM-Newton pointings. We investigate
automating optical follow-up of cluster candidates using the SDSS public
archive, concentrating on 42 XMM observations that overlap the SDSS First Data
Release. Restricting to the inner 11 arcminutes of the XMM field-of-view gives
637 unique X-ray sources across a 3.09 deg^2 region with SDSS coverage. The log
N-log S relation indicates survey completeness to a flux limit of around
1x10^{-14} erg s^-1 cm^-2. We have cross-correlated XMM point sources with SDSS
quasars, finding 103 unique matches from which we determine a matching radius
of 3.8 arcseconds. Using this we make immediate identifications of roughly half
of all XMM point sources as quasars (159) or stars (55). We have estimated the
typical error on SDSS-determined photometric cluster redshifts to be 5% for
relaxed systems, and 11% for disturbed systems, by comparing them to
spectroscopic redshifts for eight previously-known clusters. The error for
disturbed systems may be problematic for cluster surveys relying on photometric
redshifts alone. We use the False Discovery Rate to select 41 XMM sources (25
point-like, 16 extended) statistically associated with SDSS galaxy
overdensities. Of the extended sources, 5 are new cluster candidates and 11 are
previously-known clusters (0.044<z<0.782). There are 83 extended X-ray sources
not associated with SDSS galaxy overdensities, which are strong candidates for
new high-redshift clusters. We highlight two previously-known z>1 clusters
rediscovered by our wavelet-based detection software. These results show that
the SDSS can provide useful automated follow-up to X-ray cluster surveys, but
cannot provide all the optical follow-up necessary for X-ray cluster surveys.


title: The effect of dust settling on the appearance of protoplanetary disks

abstract:
  We analyze how the process of dust settling affects the spectral energy
distribution and optical appearance of protoplanetary disks. Using simple
analytic estimates on the one hand, and detailed 1+1-D models on the other
hand, we show that, while the time scale for settling down to the equator may
exceed the life time of the disk, it takes much less time for even small grains
of 0.1 micron to settle down to a few pressure scale heights. This is often
well below the original location of the disk's photosphere, and the disk
therefore becomes effectively 'flatter'. If turbulent stirring is included, a
steady state solution can be found, which is typically reached after a few
times 1E5 years. Dependent on the strength of the turbulence, the shape of the
disk in such a steady state can be either fully flaring, or flaring only up to
a certain radius and self-shadowed beyond that radius. We show that these
partly self-shadowed disks have a much weaker mid- to far-infrared flux than
the fully flaring ones. We also show that these self-shadowed regions of the
disk are very weak in resolved images of scattered light, in contrast to the
fully flaring disks. From the calculations with compact grains it follows that,
after about 1E6 years, most disks should be self-shadowed. The fact that some
older disks are still observed with the characteristics of flaring disks
therefore seems somewhat inconsistent with the time scales predicted by the
settling model based on compact grains. This suggests that perhaps even the
small grains (lesssim 0.1 micron) have a porous or fractal structure, or that
the different geometries of observed disks is merely a reflection of the
turbulent state of these disks.


title:
Gravitational bar and spiral arm torques from K_s-band observations and
  implications for the pattern speeds

abstract:
  We have obtained deep near-infrared K_s-band William Herschel Telescope
observations of a sample of 15 nearby spiral galaxies having a range of Hubble
types and apparent bar strengths. The near-infrared light distributions are
converted into gravitational potentials, and the maximum relative gravitational
torques due to the bars and the spirals are estimated. We find that spiral
strength, Q_s, and bar strength, Q_b, correlate well with other measures of
spiral arm and bar amplitudes, and that spiral and bar strengths also correlate
well with each other. We also find a correlation between the position angle of
the end of the bar and the position angle of the inner spiral. These
correlations suggest that the bars and spirals grow together with the same
rates and pattern speeds. We also show that the strongest bars tend to have the
most open spiral patterns. Because open spirals imply high disk-to-halo mass
ratios, bars and spirals most likely grow together as a combined disk
instability. They stop growing for different reasons, however, giving the
observed variation in bar-spiral morphologies. Bar growth stops because of
saturation when most of the inner disk is in the bar, and spiral growth stops
because of increased stability as the gas leaves and the outer disk heats up.


title: Seed fields for galactic dynamos by the magnetorotational instabilities

abstract:
  A linear but global numerical model for the magnetorotational instability
(MRI) in disk geometry is considered to estimate the instability parameters for
galaxies. Similarity rules suggested by a local analysis are applied to reveal
a universal behavior approached by the results of global calculations for large
magnetic Prandtl numbers. The findings are used to estimate the MRI
characteristics for galaxies with their very large magnetic Prandtl numbers
which cannot be attained in any numerical simulations. The resulting minimum
field for the instability, Bmin 10-25 G, is small compared to any seed fields
currently discussed. The growth times of MRI are estimated to be on the order
of the rotation period of the inner rigidly-rotating core, i.e. ~100 Myr.
Global MRI excites preferentially the magnetic field modes of quadrupolar
symmetry.


title:
Soft X-ray precursors of the non-thermal flares in blazars - theoretical
  predictions

abstract:
  Popular internal shock models, developed to explain production of high energy
flares in blazar jets, involve collisions between local overdensities of matter
being ejected by a central engine and moving along the jet with different
velocities. Prior to such collisions, the matter is relatively cold and
therefore does not produce intrinsic non-thermal radiation. However, due to
Comptonization of external radiation by cold electrons, the presence of such
matter should be apparent by prominent precursor soft X-ray flares, visible
prior to non-thermal $\gamma$-ray flares. In this paper we discuss the
predicted properties of such precursors and study the dependence of their
properties (luminosities and light curves) on kinematic parameters of
relativistic ejecta and on an angle of view. We demonstrate that the lack of
evidence for luminous soft X-ray precursors can be reconciled with our
predictions for their properties if acceleration and collimation of a jet takes
about three distance decades. We briefly discuss the severe constraints on the
internal shock models that would be imposed by a non-detection of such
precursors.


title: A Unified Picture of the FIP and Inverse FIP Effects

abstract:
  We discuss models for coronal abundance anomalies observed in the coronae of
the sun and other late-type stars following a scenario first introduced by
Schwadron, Fisk & Zurbuchen of the interaction of waves at loop footpoints with
the partially neutral gas. Instead of considering wave heating of ions in this
location, we explore the effects on the upper chromospheric plasma of the wave
ponderomotive forces. These can arise as upward propagating waves from the
chromosphere transmit or reflect upon reaching the chromosphere-corona
boundary, and are in large part determined by the properties of the coronal
loop above. Our scenario has the advantage that for realistic wave energy
densities, both positive and negative changes in the abundance of ionized
species compared to neutrals can result, allowing both FIP and Inverse FIP
effects to come out of the model. We discuss how variations in model parameters
can account for essentially all of the abundance anomalies observed in solar
spectra. Expected variations with stellar spectral type are also qualitatively
consistent with observations of the FIP effect in stellar coronae.


title: Diurnal and Annual Modulation of Cold Dark Matter Signals

abstract:
  We calculate the diurnal and annual modulation of the signals in axion and
WIMP dark matter detectors on Earth caused by a cold flow of dark matter in the
Solar neighborhood. The effects of the Sun's and the Earth's gravity, and of
the orbital and rotational motions of the Earth are included. A cold flow on
Earth produces a peak in the spectrum of microwave photons in cavity detectors
of dark matter axions, and a plateau in the nuclear recoil energy spectrum in
WIMP detectors. Formulas are given for the positions and heights of these peaks
and plateaux as a function of time in the course of day and year, including all
corrections down to the 0.1% level of precision. The results can be applied to
an arbitrary dark matter velocity distribution $f(\vec{v})$ by integrating the
one-flow results over velocities. We apply them to the set of flows predicted
by the caustic ring model of the Galactic halo. The caustic ring model predicts
the dark matter flux on Earth to be largest in December $\pm$ one month.
Nonetheless, because of the role of energy thresholds, the model is consistent
with the annual modulation results published by the DAMA collaboration provided
the WIMP mass is larger than approximately 100 GeV.


title:
Supernova / Acceleration Probe: A Satellite Experiment to Study the
  Nature of the Dark Energy

abstract:
  The Supernova / Acceleration Probe (SNAP) is a proposed space-based
experiment designed to study the dark energy and alternative explanations of
the acceleration of the Universe's expansion by performing a series of
complementary systematics-controlled measurements. We describe a
self-consistent reference mission design for building a Type Ia supernova
Hubble diagram and for performing a wide-area weak gravitational lensing study.
A 2-m wide-field telescope feeds a focal plane consisting of a 0.7
square-degree imager tiled with equal areas of optical CCDs and near infrared
sensors, and a high-efficiency low-resolution integral field spectrograph. The
SNAP mission will obtain high-signal-to-noise calibrated light-curves and
spectra for several thousand supernovae at redshifts between z=0.1 and 1.7. A
wide-field survey covering one thousand square degrees resolves ~100 galaxies
per square arcminute. If we assume we live in a cosmological-constant-dominated
Universe, the matter density, dark energy density, and flatness of space can
all be measured with SNAP supernova and weak-lensing measurements to a
systematics-limited accuracy of 1%. For a flat universe, the
density-to-pressure ratio of dark energy can be similarly measured to 5% for
the present value w0 and ~0.1 for the time variation w'. The large survey area,
depth, spatial resolution, time-sampling, and nine-band optical to NIR
photometry will support additional independent and/or complementary dark-energy
measurement approaches as well as a broad range of auxiliary science programs.
(Abridged)


title: The Swift Gamma-Ray Burst Mission

abstract:
  The Swift mission, scheduled for launch in early 2004, is a multiwavelength
observatory for gamma-ray burst (GRB) astronomy. It is the first-of-its-kind
autonomous rapid-slewing satellite for transient astronomy and pioneers the way
for future rapid-reaction and multiwavelength missions. It will be far more
powerful than any previous GRB mission, observing more than 100 bursts per year
and performing detailed X-ray and UV/optical afterglow observations spanning
timescales from 1 minute to several days after the burst. The objectives are to
determine the origin of GRBs; classify GRBs and search for new types; study the
interaction of the ultra-relativistic outflows of GRBs with their surrounding
medium; and use GRBs to study the early universe out to z>10. The mission is
being developed by a NASA-led international collaboration. It will carry three
instruments: a new-generation wide-field gamma-ray (15-150 keV) detector; a
narrow-field X-ray telescope; and a narrow-field UV/optical telescope. Redshift
determinations will be made for most bursts. In addition to the primary GRB
science, the mission will perform a hard X-ray survey to a sensitivity of ~1
mCrab (~2x10^{-11} erg cm^{-2} s^{-1} in the 15-150 keV band), more than an
order of magnitude better than HEAO A-4. A flexible data and operations system
will allow rapid follow-up observations of all types of high-energy transients,
with rapid data downlink and uplink available through the NASA TDRSS system.
The mission is currently funded for 2 years of operations and the spacecraft
will have a lifetime to orbital decay of ~8 years. [ABRIDGED]


title:
A Halo-Based Galaxy Group Finder: Calibration and Application to the
  2dFGRS

abstract:
  We use the halo occupation model to calibrate galaxy group finders in
magnitude-limited redshift surveys. Since, according to the current scenario of
structure formation, galaxy groups are associated with cold dark matter halos,
we make use of the properties of the halo population in the design of our group
finder. The method starts with an assumed mass-to-light ratio to assign a
tentative mass to each group. This mass is used to estimate the size and
velocity dispersion of the underlying halo that hosts the group, which in turn
is used to determine group membership (in redshift space). This procedure is
repeated until no further changes occur in group memberships. We find that the
final groups selected this way are insensitive to the mass-to-light ratio
assumed. We use mock catalogues, constructed using the conditional luminosity
function (CLF), to test the performance of our group finder in terms of
completeness of true members and contamination by interlopers. Our group finder
is more successful than the conventional Friends-of-Friends group finder in
assigning galaxies in common dark matter halos to a single group. We apply our
group finder to the 2-degree Field Galaxy Redshift Survey and compare the
resulting group properties with model predictions based on the CLF. For the
$\Lambda$CDM `concordance' cosmology we find a clear discrepancy between the
model and data in the sense that the model predicts too many rich groups. In
order to match the observational results we have to either increase the
mass-to-light ratios of rich clusters to a level significantly higher than
current observational estimates, or to assume $\sigma_8 \simeq 0.7$, compared
to the `concordance' value of 0.9.


title: Supersymmetric Dark Matter and the Extragalactic Gamma Ray Background

abstract:
  We trace the origin of the newly determined extragalactic gamma ray
background from EGRET data to an unresolved population of blazars and
neutralino annihilation in cold dark matter halos. Using results of
high-resolution simulations of cosmic structure formation, we calculate
composite spectra and compare with the EGRET data. The resulting best-fit value
for the neutralino mass is m_chi = (515 +/- 110/75) GeV (systematic errors
\~30%).


title:
RXTE broadband X-ray spectra of intermediate polars and white dwarf mass
  estimates

abstract:
  We present results of an analysis of broadband spectra of 14 intermediate
polars obtained with the RXTE observatory (PCA and HEXTE spectrometers, 3-100
keV). By means of our calculations of the structure and the emergent spectrum
of the post-shock region of intermediate polars we fitted the observed spectra
and obtained estimates of the white dwarf masses. The estimated masses are
compared with masses obtained by other authors.


title: A natural mechanism to induce an electric charge into a black hole

abstract:
  We present a natural mechanism which may induce an electric charge into an
accretting black hole in the presence of a strong, high energy radiation field.
We study this mechanism using Newtonian physics, and we also discuss the
process within the context of a Kerr Newman black hole. Finally, we consider
possible astrophysical applications in X-ray variability and jet formation in
the Active Galactic Nuclei (AGN).


title:
Quasisoft X-Ray Sources: Unusual States of Stellar-Mass Objects, or
  Intermediate Mass Black Holes?

abstract:
  Chandra observations of nearby galaxies have revealed a number of X-ray
sources characterized by high luminosities ($L_X > \sim10^{36}$ erg s$^{-1}$)
and $k T$ in the range $100 - 350$ eV. These ``quasisoft X-ray sources'' (QSSs)
are harder than luminous supersoft X-ray sources (SSSs), whose characteristic
temperatures are tens of eV, but, with little or no emission above 2 keV, they
are significantly softer than most canonical X-ray sources. They are likely to
include a range of physical systems; some may be common systems in unusual
states: neutron stars or stellar-mass black holes (BHs), or SNRs. Others may be
accreting BHs of intermediate mass. We have analyzed {\it Chandra} data from
$19 $ near-by galaxies to identify QSSs with sufficiently high count rates to
allow spectral fits. Six of these galaxies have been studied in great detail;
in these we find 89 SSSs and 122 QSSs. In this paper we present spectra for
QSSs those with more than 50 counts. We also use data from six of these
galaxies to study the broadband spectral distributions of QSSs and to compare
them with those of other X-ray sources. Since QSSs in the Milky Way are likely
to be missed by our selection procedures, we discuss other signatures by which
they can be found. If some of the QSSs for which we have spectra are accreting
BHs, the lower bounds for the BH mass range from roughly $30 M_\odot$ to $1000
M_\odot$.


title: A Quasar Without Broad Lyman-alpha Emission

abstract:
  The z=3.02 quasar SDSS J095253.83+011421.9 exhibits broad metal-line emission
(CIV FWHM=9000 km/s), but broad Ly-alpha emission is not present. Instead, only
a narrow Ly-alpha line is observed (FWHM=1140 km/s). The large CIV/Ly-alpha
ratio in the broad-line region (BLR) emission from this object can be matched
most closely by a BLR dominated by gas at very high densities (10^15 cm^-3),
which suppresses the Ly-alpha emission, and illuminated by an incident
power-law extending to ~200 micron, which yields increased emission from purely
collisionally excited coolant lines (such as CIV, NV and OVI) but not from
recombination lines like Ly-alpha. However, the strong CIII emission predicted
by this model is not observed, and the observed broad CIII] emission must come
from a lower-density BLR component and should be accompanied by broad Ly-alpha
emission which is not observed. The least unlikely explanation for this
spectrum seems to be that any intrinsic broad Ly-alpha emission is removed by
smooth NV absorption in the red wing of the Ly-alpha emission line and by
smooth Ly-alpha absorption in the blue wing of the Ly-alpha emission line. This
postulated smooth absorption would be in addition to the strong, associated,
narrow absorption seen in numerous ions. Smooth absorption in Ly-alpha, NV and
OVI but not in CIV would be unusual, but not impossible, although it is
suspicious that the postulated absorption must almost exactly cancel the
postulated intrinsic broad emission. We conclude that the spectrum of SDSS
J0952+0114 appears unique (among ~3600 SDSS spectra of quasars at z>2.12)
because of some_combination_ of unusual parameters, and we discuss possible
observations to determine the combination of circumstances responsible for the
spectrum.


title:
A Laboratory for Constraining Cosmic Evolution of the Fine Structure
  Constant: Conjugate 18 cm OH Lines Toward PKS 1413+135 at z=0.2467

abstract:
  We report the detection of the satellite 18 cm OH lines at 1612 and 1720 MHz
in the z=0.2467 molecular absorption system toward the radio source PKS
1413+135. The two OH lines are conjugate; the 1612 MHz line is seen in
absorption while the 1720 MHz line is seen in weak maser emission of equal, but
negative, optical depth. We do not detect the main 18 cm OH lines at 1667 and
1665 MHz down to 1.1 mJy rms in 4.0 km/s channels. The detected and undetected
18 cm OH lines support a scenario of radiatively pumped stimulated absorption
and emission with pumping dominated by the intraladder 119 micron line of OH,
suggesting a column density N(OH) ~= 10^15 to 10^16 cm^-2. Combined with
simultaneous HI 21 cm observations and published CO data, we apply the OH
redshifts to measurements of cosmic evolution of the fine structure constant
alpha = e^2/(hbar c). We obtain highly significant (~25 sigma) velocity offsets
between the OH and HI lines and the OH and CO lines, but measurements of
alpha-independent systematics demonstrate that the observed velocity
differences are entirely attributable to physical velocity offsets between
species rather than a change in alpha. The OH alone, in which conjugate line
profiles guarantee that both lines originate in the same molecular gas,
provides a weak constraint of Delta alpha/alpha_o = (+0.51 +/- 1.26) x 10^-5 at
z=0.2467. Higher frequency OH line detections can provide a larger lever arm on
Delta alpha and can increase precision by an order of magnitude. The OH
molecule can thus provide precise measurements of the cosmic evolution of alpha
that include quantitative constraints on systematic errors. Application of this
technique is limited only by the detectability of |tau|~0.01 OH lines toward
radio continuum sources and may be possible to z~5.


title: The Discovery of New Galaxy Members in the NGC 5044 and NGC 1052 Groups

abstract:
  We present the results of neutral hydrogen (HI) observations of the NGC 5044
and NGC 1052 groups, as part of a GEMS (Group Evolution Multiwavelength Study)
investigation into the formation and evolution of galaxies in nearby groups.
Two new group members have been discovered during a wide-field HI imaging
survey conducted using the ATNF Parkes telescope. These results, as well as
those from followup HI synthesis and optical imaging, are presented here.
J1320-1427, a new member of the NGC 5044 Group, has an HI mass of
M_HI=1.05e9Msun and M_HI/L_B=1.65 Msun/Lsun, with a radial velocity of
v=2750km/s. The optical galaxy is characterised by two regions of star
formation, surrounded by an extended, diffuse halo. J0249-0806, the new member
of the NGC 1052 Group, has M_HI=5.4e8Msun, M_HI/L_R=1.13 Msun/Lsun and
v=1450km/s. The optical image reveals a low surface brightness galaxy. We
interpret both of these galaxies as irregular type, with J0249-0806 possibly
undergoing first infall into the NGC 1052 group.


title:
Stellar polytropes and Navarro--Frenk--White dark matter halos: a
  connection to Tsallis entropy

abstract:
  We present an alternative for the description of galactic halos based on
Tsallis' non--extensive entropy formalism; on this scheme, halos are stellar
polytropes characterized by three parameters, the central density, $\rho_c$,
the central velocity dispersion, $\sigma_c$ and the polytropic index, $n$. To
evaluate these parameters we take the Navarro-Frenk-White paradigm as a
comparative model and make the following assumptions: both halo models must
have the same virial mass, the same total energy and the same maximal velocity.
These three conditions fix all the parameters for a given stellar polytrope
allowing us to compare both halo models. The halos studied have virial masses
on the range $10^{12}-10^{15} M_\odot$, and it was found after the analysis
that they are described, at all scales, by almost the same polytropic index,
$n\approx 4.8$, implying an empirical estimation of Tsallis non--extensive
parameter for this type of dynamical systems: $q\approx 1.3$.


title:
HI in NGC 5433 and its Environment: High-Latitude Emission in a Small
  Galaxy Group

abstract:
  We present HI synthesis maps of the edge-on starburst NGC 5433 and its
environment, obtained with the VLA in its C and D configurations. The
observations and spectral model residuals of the main disc emission in NGC 5433
reveal 3 extraplanar features. We associate 2 of these features with coherent
extraplanar extensions across multiple spectral channels in our data, including
a complete loop in position-velocity space. Interpreting the latter as an
expanding shell we derive a corresponding input energy of 2 x 10^54 ergs,
comparable to that for the largest supershells found in the Galaxy and those in
other edge-on systems. NGC 5433 is in a richer environment than previously
thought. We confirm that KUG 1359+326 is a physical companion to NGC 5433 and
find two new faint companions, both with Minnesota Automated Plate Scanner
identifications, that we label SIS-1 and SIS-2. Including the more distant IC
4357, NGC 5433 is the dominant member of a group of at least 5 galaxies,
spanning over 750 kpc in a filamentary structure. A variety of evidence
suggests that interactions are occurring in this group. While a number of
underlying mechanisms are consistent with the morphology of the high-latitude
features in NGC 5433, we argue that environmental effects may play a role in
their generation.


title:
Models of Chemistry, Thermal Balance and Infrared Spectra from
  Intermediate-Aged Disks around G and K stars

abstract:
  We model gas and dust emission from regions 0.3-20 AU from a central low mass
star in intermediate-aged(~10Myr) disks with optically thin dust. The models
treat thermal balance and chemistry self-consistently and calculate the
vertical density temperature structure of the gas in a disk. The gas and dust
temperatures are calculated separately. We focus on IR gas emission lines and
find that the [SI]25.23 micron line is the strongest emission line for a wide
range of disk and stellar parameters, followed by emission from [SiII]34.8 um,
[FeII]26 um and [OI]63um. [FeI]24um and rotational lines of OH and H2O are
strong when gas masses are high (>0.1 M_J). Emission from the rotational lines
of H2 is difficult to detect, unless disk gas masses are substantial (>0.1
M_J).


title: Mid Infrared Observations of Van Maanen 2: No Substellar Companion

abstract:
  The results of a comprehensive infrared imaging search for the putative 0.06
solar mass astrometric companion to the 4.4 pc white dwarf van Mannen 2 are
reported. Adaptive optics images acquired at 3.8 microns reveal a diffraction
limited core of 0.09" and no direct evidence of a secondary. Models predict
that at 5 Gyr, a 50 jupiter mass brown dwarf would be only 1 magnitude fainter
than van Maanen 2 at this wavelength and the astrometric analysis suggested a
separation of 0.2". In the case of a chance alignment along the line of sight,
a 0.4 mag excess should be measured. An independent photometric observation at
the same wavelength reveals no excess. In addition, there exist published ISO
observations of van Maanen 2 at 6.8 and 15.0 microns which are consistent with
photospheric flux of a 6750 K white dwarf. If recent brown dwarf models are
correct, there is no substellar companion with T > 500 K.


title: X-Ray Spectral Variability in Cygnus X-1

abstract:
  Spectral variability in different energy bands of X-rays from Cyg X-1 in
different states is studied with RXTE observations and time domain approaches.
In the hard tail of energy spectrum above $\sim 10$ keV, average peak aligned
shots are softer than the average steady emission and the hardness ratio
decreases when the flux increases during a shot for all states. In regard to a
soft band lower $\sim 10$ keV, the hardness in the soft state varies in an
opposite way: it peaks when the flux of the shot peaks. For the hard and
transition states, the hardness ratio in respect to a soft band during a shot
is in general lower than that of the steady component and a sharp rise is
observed at about the shot peak. For the soft state, the correlation
coefficient between the intensity and hardness ratio in the hard tail is
negative and decreases monotonically as the timescale increases from 0.01 s to
50 s, which is opposite to that in regard to a soft band. For the hard and
transition states, the correlation coefficients are in general negative and
have a trend of decrease with increasing timescale.


title: Nonaxisymmetric Neutral Modes in Relativistic Disks

abstract:
  We perform a linear stability analysis of the axisymmetric, relativistic,
self-similar isothermal disk against non-axisymmetric perturbations. Two sets
of neutral modes are discovered. The first set corresponds to marginally
unstable perturbations driven by gravitational radiation, and the other signals
the onset of bifurcation to non-axisymmetric equilibrium solutions to the
Einstein equations.


title: Outflows in Regions of Star Formation

abstract:
  The high spatial and spectral resolution offered by the new generation of
infrared spectrometers at ESO is optimally suited for the observational study
of outflows from young stellar objects. Models of interstellar shock waves
would benefit from observations of spectrally resolved line profiles. This
applies also to attempts of measuring the rotation rates of jets very close to
their driving source, which in general suffer considerable extinction.
Observations of forbidden lines of ionised iron, [Fe II], could be used to
accomplish this. The possibility of using rotational lines of molecular
hydrogen, H2, to study the temporal evolution of outflow and disk gas is
discussed. Similarly, high resolution IR observations of fluorescent water
lines, H2O, open up the possibility to access outflow and disk water.


title: Breaking the core-envelope symmetry in p-mode pulsating stars

abstract:
  It has been shown that there is a potential ambiguity in the asteroseismic
determination of the location of internal structures in a pulsating star. We
show how, in the case of high-order non-radial acoustic modes, it is possible
to remove this ambiguity by considering modes of different degree. To support
our conclusions we have investigated the seismic signatures of sharp density
variations in the structure of quasi-homogeneous models.


title: On the nature of bimodal initial velocity distribution of neutron stars

abstract:
  We propose that the bimodal nature of the kick velocity distribution of radio
pulsars is connected with the dichotomy between hadronic stars ({\it i.e.}
neutron stars with no quark matter content) and quark stars. Bimodality can
appear due to different mechanisms of explosion which leads to the formation of
two types of compact stars or due to two different sets of parameters mastering
a particular kick mechanism. The low velocity maximum (at $\sim 100$ km
s$^{-1}$) is connected with hadronic star formation, whereas the second peak
corresponds to quark stars. In the model of delayed collapse of hadronic stars
to quark stars (Berezhiani et al. 2003\nocite{bbd2003}) quark deconfinement
leads to a second energy release, and to a second kick, in addition to the kick
imparted to the newly formed hadronic star during the supernova explosion. If
the electromagnetic rocket mechanism can give a significant contribution to
pulsar kicks, then the high velocity peak can be connected with the shorter
initial spin periods of quark stars with respect to hadronic stars. We discuss
{\it pro et contra} of these scenarios.


title: Radio emission and particle acceleration in plerionic supernova remnants

abstract:
  Plerionic supernova remnants exhibit radio emission with remarkably flat
spectral indices ranging from $\alpha=0.0$ to $\alpha=-0.3$. The origin of very
hard particle energy distributions still awaits an explanation, since shock
waves generate particle distributions with synchrotron spectra characterized by
$\alpha\le-0.5$. Acceleration of high energy leptons in magnetohydrodynamic
turbulence instead may be responsible for the observed hard spectra. This
process is studied by means of relativistic test particle calculations using
electromagnetic fields produced by three-dimensional simulations of resistive
magnetohydrodynamical turbulence. The particles receive power-law energy
spectra $N(\gamma)\propto \gamma^{-s}$ with $s$ ranging from 1.2 to 1.6, i.e.
particle spectra that are required to explain the radio emission of plerions.


title:
The HARPS search for southern extra-solar planets I. HD330075 b: a new
  'hot Jupiter'

abstract:
  We report on the first extra-solar planet discovered with the brand new HARPS
instrument. The planet is a typical 'hot Jupiter' with m2sini = 0.62 MJup and
an orbital period of 3.39 days, but from the photometric follow-up of its
parent star HD330075 we can exclude the presence of a transit. The induced
radial-velocity variations exceed 100 m/s in semi-amplitude and are easily
detected by state-of-the-art spectro-velocimeters. Nevertheless, the faint
magnitude of the parent star (V = 9.36) benefits from the efficient instrument:
With HARPS less than 10 observing nights and 3 hours of total integration time
were needed to discover the planet and characterize its orbit. The orbital
parameters determined from the observations made during the first HARPS run in
July 2003 have been confirmed by 7 additional observations carried out in
February 2004. The bisector analysis and a photometric follow-up give no hint
for activity-induced radial-velocity variations, indicating that the velocity
curve is best explained by the presence of a low-mass companion to the star. In
this paper we present a set of 21 measurements of excellent quality with
weighted rms as low as 2.0 m/s. These measurements lead to a well defined orbit
and consequently to the precise orbital parameters determination of the
extra-solar planet HD330075b.