title:
High Resolution Optical Velocity Fields of 11 Low Surface Brightness
  Galaxies

abstract:
  We present high resolution two-dimensional velocity fields from integral
field spectroscopy along with derived rotation curves for eleven low surface
brightness galaxies. We fit NFW and pseudo-isothermal halo models to the new
data combined with previous long-slit and HI data. In most cases we find the
pseudo-isothermal halo to better represent the data than the NFW halo, as the
NFW concentrations are often lower than expected for a LambdaCDM cosmology. We
also compare our results to previous studies and find that including the new
two-dimensional optical data does not significantly alter the halo parameters,
but does decrease the uncertainties by roughly a factor of 2.


title:
FLAMINGOS-2: The Facility Near-Infrared Wide-field Imager & Multi-Object
  Spectrograph for Gemini

abstract:
  We report on the design and status of the FLAMINGOS-2 instrument - a
fully-cryogenic facility near-infrared imager and multi-object spectrograph for
the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical
optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular
field-of-view on a 2048x2048-pixel HAWAII-2 0.9-2.4 mm detector array. A
slit/decker wheel mechanism allows the selection of up to 9 multi-object
laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute
field of view, and selectable grisms provide resolutions from $\sim$ 1300 to
$\sim $3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also
compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing
multi-object spectroscopic capabilities over a 3x1-arcminute field with high
spatial resolution (0.09-arcsec/pixel). We review the designs of optical,
mechanical, electronics, software, and On-Instrument WaveFront Sensor
subsystems. We also present the current status of the project, currently in
final testing in mid-2006.


title: The Maximum Mass of Star Clusters

abstract:
  When an universal untruncated star cluster initial mass function (CIMF)
described by a power-law distribution is assumed, the mass of the most massive
star cluster in a galaxy (M_max) is the result of the size-of-sample (SoS)
effect. This implies a dependence of M_max on the total number of star clusters
(N). The SoS effect also implies that M_max within a cluster population
increases with equal logarithmic intervals of age. This is because the number
of clusters formed in logarithmic age intervals increases (assuming a constant
cluster formation rate). This effect has been observed in the SMC and LMC.
Based on the maximum pressure (P_int) inside molecular clouds, it has been
suggested that a physical maximum mass (M_max[phys]) should exist. The theory
predicts that M_max[phys] should be observable, i.e. lower than M_max that
follows from statistical arguments, in big galaxies with a high star formation
rate. We compare the SoS relations in the SMC and LMC with the ones in M51 and
model the integrated cluster luminosity function (CLF) for two cases: 1) M_max
is determined by the SoS effect and 2) M_max=M_max[phys]=constant. The observed
CLF of M51 and the comparison of the SoS relations with the SMC and LMC both
suggest that there exists a M_max[phys] of 5*10^5 M_sun in M51. The CLF of M51
looks very similar to the one observed in the ``Antennae'' galaxies. A direct
comparison with our model suggests that there M_max[phys]=2*10^6 M_sun.


title:
Non-Gaussian corrections to the probability distribution of the
  curvature perturbation from inflation

abstract:
  We show how to obtain the probability density function for the amplitude of
the curvature perturbation, R, produced during an epoch of slow-roll,
single-field inflation, working directly from n-point correlation functions of
R. These n-point functions are the usual output of quantum field theory
calculations, and as a result we bypass approximate statistical arguments based
on the central limit theorem. Our method can be extended to deal with arbitrary
forms of non-Gaussianity, appearing at any order in the n-point hierarchy. We
compute the probability density for the total smoothed perturbation within a
Hubble volume, \epsilon, and for the spectrum of \epsilon. When only the
two-point function is retained, exact Gaussian statistics are recovered. When
the three-point function is taken into account, we compute explicitly the
leading slow-roll correction to the Gaussian result.


title: An Energetic Afterglow From A Distant Stellar Explosion

abstract:
  We present the discovery of radio afterglow emission from the high redshift
(z=6.295) burst GRB 050904. The peak flux density for this burst is similar to
typical low-redshift gamma-ray bursts (GRB). We further show that beyond a
redshift of order unity, the flux density of radio afterglows are largely
insensitive to redshift, consistent with predictions. By combining the existing
X-ray, near-infrared and radio measurements, we derive estimates for the
kinetic energy and opening angle of the blast wave, and for the density of the
circumburst medium into which it expands. Both the kinetic and radiated energy
indicate that GRB 050904 was an unusally energetic burst (10**52 erg). More
importantly, we are able to make an in situ measurement of the density
structure of the circumburst medium. We conclude that GRB 050904 exploded into
a constant density medium with n=680 cm**-3, which is two orders of magnitude
above the nominal value for low-redshift GRBs. The next generation of
centimeter (EVLA) and millimeter radio instuments (ALMA) will be able to
routinely detect events like GRB 050904 and use them to study magnetic fields,
and the atomic and molecular gas in the high redshift Universe.


title: Environment and the cosmic evolution of star formation

abstract:
  We present a mark correlation analysis of the galaxies in the Sloan Digital
Sky Survey using weights provided by MOPED. The large size of the sample
permits statistically significant statements about how galaxies with different
metallicities and star formation histories are spatially correlated. Massive
objects formed a larger fraction of their stars at higher redshifts and over
shorter timescales than did less massive objects (sometimes called
down-sizing). We find that those galaxies which dominated the cosmic star
formation at z~3 are predominantly in clusters today, whereas galaxies which
dominate the star formation at z~0 inhabit substantially lower mass objects in
less dense regions today. Hence, our results indicate that star formation and
chemical enrichment occured first in the denser regions of the Universe, and
moved to less dense regions at later times.


title: Neutral atom transport from the termination shock to 1 AU

abstract:
  Dynamics of H, D, and heavy Energetic Neutral Atoms (ENA) between the
termination shock and 1 AU is discussed in the context of the forthcoming NASA
SMEX mission IBEX. In particular, effects of the velocity-dependent radiation
pressure on atomic trajectories are considered and ionization losses between TS
and 1 AU are studied. It is shown, among others, that most of the dynamical
effects and ionization losses are induced within a few AU from the Sun, which
translates to the time domain into $\sim 1 - 3$ solar rotations before
detection. This loosens considerably time requirements for tracking the
ionization and radiation pressure history to just prior 3 months. ENA seem
excellent tracers of the processes within the heliospheric interface, with the
transport effects between the termination shock and detector relatively mild
and easy to account for.


title: Filaments, Bubbles, and Weak Shocks in the Gaseous Atmosphere of M87

abstract:
  We present the first results from a 500 ksec Chandra ACIS-I observation of
M87. At soft energies (0.5-1.0 keV), we detect filamentary structures
associated with the eastern and southwestern X-ray and radio arms. Many
filaments are spatially resolved with widths of ~300 pc. This filamentary
structure is particularly striking in the eastern arm where we suggest the
filaments are outer edges of a series of plasma-filled, buoyant bubbles whose
ages differ by ~6 x 10^6 years. These X-ray structures may be influenced by
magnetic filamentation. At hard energies (3.5-7.5 keV), we detect a nearly
circular ring of outer radius 2.8' (13 kpc) which provides an unambiguous
signature of a weak shock, driven by an outburst from the SMBH. The density
rise in the shock is ~1.3 (Mach number, M~1.2). The observed spectral hardening
in the ring corresponds to a temperature rise T_shock / T_0 ~ 1.2, or M~1.2, in
agreement with the Mach number derived independently from the gas density.
Thus, for the first time, we detect gas temperature and density jumps
associated with a classical shock in the atmosphere around a supermassive black
hole. We also detect two additional surface brightness edges and pressure
enhancements at radii of ~0.6' and ~1'. The ~0.6' feature may be
over-pressurized thermal gas surrounding the relativistic plasma in the radio
cocoon, the ``piston'', produced by the current episode of AGN activity. The
over-pressurized gas is surrounded by a cool gas shell. The ~1' feature may be
an additional weak shock from a secondary outburst. In an earlier episode, the
``piston'' was responsible for driving the 2.8' shock.


title:
The star formation rate at redshift one: H-alpha spectroscopy with
  CIRPASS

abstract:
  We have conducted an H-alpha survey of 38 0.77<z<1 galaxies over ~100
arcmin^2 of the Hubble Deep Field North and Flanking Fields, to determine star
formation rates (SFRs), with the near-infrared multi-object spectrograph
CIRPASS on the WHT. This represents the first successful application of this
technique to observing high redshift galaxies. Stacking the spectra in the
rest-frame to infer a total SFR for the field, we find a lower limit
(uncorrected for dust reddening) on the star formation rate density at redshift
z = 1 of 0.04Msol/yr/Mpc^3. This implies rapid evolution in the star formation
rate density from z = 0 to z = 1 which is proportional to (1+z)^{3.1}.


title: AGN Jet Mass Loading and Truncation by Stellar Winds

abstract:
  Active Galactic Nuclei can produce extremely powerful jets. While tightly
collimated, the scale of these jets and the stellar density at galactic centers
implies that there will be many jet/star interactions, which can mass-load the
jet through stellar winds. Previous work employed modest wind mass outflow
rates, but this does not apply when mass loading is provided by a small number
of high mass-loss stars. We construct a framework for jet mass-loading by
stellar winds for a broader spectrum of wind mass-loss rates than has been
previously considered. Given the observed stellar mass distributions in
galactic centers, we find that even highly efficient (0.1 Eddington luminosity)
jets from supermassive black holes of masses $M_{BH} \la 10^4M_{\odot}$ are
rapidly mass loaded and quenched by stellar winds. For $10^4
M_{\odot}<M_{BH}<10^8 M_{\odot}$, the quenching length of highly efficient jets
is independent of the jet's mechanical luminosity. Stellar wind mass-loading is
unable to quench efficient jets from more massive engines, but can account for
the observed truncation of the inefficient M87 jet, and implies a baryon
dominated composition on scales $\ga 2$ kpc therein even if the jet is
initially pair plasma dominated.


title: Planetary nebulae as probes for galactic chemical evolution

abstract:
  The role of planetary nebulae as probes for the galactic chemical evolution
is reviewed. Their abundances throughout the Galaxy are discussed for key
elements, in particular oxygen and other alpha elements. The abundance
distribution derived from planetary nebulae leads to the establishment of
radial abundance gradients in the galactic disk that are important constraints
to model the chemical evolution of the Galaxy. The radial gradient, well
determined for the solar neighborhood, is examined for distinct regions. For
the galactic anticenter in particular, the observational data confirm results
from galactic evolution models that point to a decreasing in the gradient slope
at large galactocentric distances. The possible time evolution of the radial
gradient is also examined comparing samples of planetary nebulae of different
ages, and the results indicate that a flattening in the gradient occurred,
which is confirmed by some galactic evolution models. The galactic bulge is
another important region whose modeling can be constrained by observational
results obtained from planetary nebulae. Results derived in the last few years
indicate that bulge nebulae have an abundance distribution similar to that of
disk objects, however with a larger dispersion.


title: Dark matter halo response to the disk growth

abstract:
  We consider the sensitivity of the circular-orbit adiabatic contraction
approximation to the baryon condensation rate and the orbital structure of dark
matter halos in the $\Lambda$CDM paradigm. Using one-dimensional hydrodynamic
simulations including the dark matter halo mass accretion history and gas
cooling, we demonstrate that the adiabatic approximation is approximately valid
even though halos and disks may assemble simultaneously. We further demonstrate
the validity of the simple approximation for $\Lambda$CDM halos with isotropic
velocity distributions using three-dimensional N-body simulations. This result
is easily understood: an isotropic velocity distribution in a cuspy halo
requires more circular orbits than radial orbits. Conversely, the approximation
is poor in the extreme case of a radial orbit halo. It overestimates the
response a core dark matter halo, where radial orbit fraction is larger.
Because no astronomically relevant models are dominated by low-angular momentum
orbits in the vicinity of the disk and the growth time scale is never shorter
than a dynamical time, we conclude that the adiabatic contraction approximation
is useful in modeling the response of dark matter halos to the growth of a
disk.


title:
Integral Field Unit Observations of NGC 891: Kinematics of the Diffuse
  Ionized Gas Halo

abstract:
  We present high and moderate spectral resolution spectroscopy of diffuse
ionized gas (DIG) emission in the halo of NGC 891. The data were obtained with
the SparsePak integral field unit at the WIYN Observatory. The wavelength
coverage includes the [NII]6548,6583, Halpha, and [SII]6716,6731 emission
lines. Position-velocity (PV) diagrams, constructed using spectra extracted
from four SparsePak pointings in the halo, are used to examine the kinematics
of the DIG. Using two independent methods, a vertical gradient in azimuthal
velocity is found to be present in the northeast quadrant of the halo, with
magnitude approximately 15-18 km/s/kpc, in agreement with results from HI
observations. The kinematics of the DIG suggest that this gradient begins at
approximately 1 kpc above the midplane. In another part of the halo, the
southeast quadrant, the kinematics are markedly different, and suggest rotation
at about 175 km/s, much slower than the disk but with no vertical gradient. We
utilize an entirely ballistic model of disk-halo flow in an attempt to
reproduce the kinematics observed in the northeast quadrant. Analysis shows
that the velocity gradient predicted by the ballistic model is far too shallow.
Based on intensity cuts made parallel to the major axis in the ballistic model
and an Halpha image of NGC 891 from the literature, we conclude that the DIG
halo is much more centrally concentrated than the model, suggesting that
hydrodynamics dominate over ballistic motion in shaping the density structure
of the halo. Velocity dispersion measurements along the minor axis of NGC 891
seem to indicate a lack of radial motions in the halo, but the uncertainties do
not allow us to set firm limits.


title: The X-ray properties of the dwarf Magellanic-type galaxy NGC 55

abstract:
  We present an analysis of the X-ray properties of the Magellanic-type galaxy
NGC 55 based on two contiguous XMM-Newton observations. We detect a total of
137 X-ray sources in the field of view, 42 of which are located within the
optical confines of the galaxy. On the basis of X-ray colour classification and
after correcting for background objects, we conclude that our source sample
includes ~ 20 X-ray binaries, 5 supernova remnants and 7 very soft sources
(including 2 good candidate supersoft sources) associated with NGC 55. Detailed
spectral and timing analysis was carried out on 4 of the brightest X-ray
sources. One of these objects is identified with a Galactic foreground star and
is a possible new RS CVn system. The other three are consistent with accreting
X-ray binaries, though further evidence of short term variability is required
to confirm this. We also find evidence of an underlying component, which is
concentrated on the bar region but has an extent of at least 6' (3 kpc) in the
plane of the galaxy and +/- 1' (+/- 500 pc) perpendicular to it. This emission
is best fitted by a thermal plasma plus power-law model but with high intrinsic
absorption consistent with its location in the central disc of the galaxy. We
interpret the soft component as diffuse thermal emission linked to regions of
current star formation, whilst the hard power-law component may originate in
unresolved X-ray binary sources. The intrinsic luminosity of this residual disc
emission may exceed Lx ~ 6e38 ergs/s (0.3-6 keV). A comparison with other
Magellanic systems confirms that, in terms of both its discrete X-ray source
population and its extended emission, NGC 55 has X-ray properties which are
typical of its class.


title: An Empirical UBVRIJHK Color-Temperature Calibration for Stars

abstract:
  A collection of Johnson/Cousins photometry for stars with known [Fe/H] is
used to generate color-color relations that include the abundance dependence.
Literature temperature and bolometric correction dependences are attached to
the color relations. The main result of this work is the tabulation of seven
colors and the V-band bolometric correction as a function of Teff, log g, and
[Fe/H] for -1.06 < V-K < 10.2 and an accompanying interpolation program.
Improvements to the present calibration would involve filling photometry gaps,
obtaining more accurate and on-system photometry, knowing better log g and
[Fe/H] values, improving the statistics for data-impoverished groups of stars
such as K dwarfs, applying small tweaks in the processing pipeline, and
obtaining better empirical temperature and bolometric correction relations,
especially for supergiants and M stars. A way to estimate dust extinction from
M dwarf colors is pointed out.


title:
SHARC-2 350 Micron Observations of Distant Submillimeter Selected
  Galaxies

abstract:
  We present 350 micron observations of 15 Chapman et al. submillimeter
galaxies (SMGs) with radio counterparts and optical redshifts. We detect 12 and
obtain sensitive upper limits for three, providing direct, precise measurements
of their far-infrared luminosities and characteristic dust temperatures. With
these, we verify the linear radio--far-infrared correlation at redshifts of z ~
1--3 and luminosities of 10^11--10^13 L_sun, with a power-law index of
1.02+-0.12 and rms scatter of 0.12 dex. However, either the correlation
constant q or the dust emissivity index beta is lower than measured locally.
The best fitting q ~ 2.14 is consistent with SMGs being predominantly starbust
galaxies, without significant AGN contribution, at far-infrared wavelengths.
Gas-to-dust mass ratios are estimated at 54+-13 (kappa_850 / 0.15 m^2 kg^-1),
depending on the absoption efficiency kappa, with intrinsic dispersion ~40%
around the mean value. Dust temperatures consistent with 34.6+-3 K
(beta/1.5)^-0.71, at z ~ 1.5--3.5, suggest that far-infrared photometric
redshifts may be viable, and perhaps accurate to 10% < dz/(1+z), for up to 80%
of the SMG population in this range, if the above temperature characterizes the
full range of SMGs. However, observed temperature evolution of T_d ~ (1+z) is
also plausible and could result from selection effects. From the observed
luminosity-temperature (L-T) relation, L ~ T_obs^(2.82+-0.29), we derive
scaling relations for dust mass versus dust temperature, and we identify
expressions to inter-relate the observed quantities. These suggest that
measurements at a single wavelength, in the far-infrared, submillimeter or
radio wave bands, might constrain dust temperatures and far-infrared
luminosities for most SMGs with redshifts at z ~ 0.5--4.


title: Manganese Abundances in Cluster and Field Stars

abstract:
  We have derived Mn abundances for more than 200 stars in 19 globular
clusters. In addition, Mn abundance determinations have been made for a
comparable number of halo field and disk stars possessing an overlapping range
of metallicities and stellar parameters. Our primary data set was comprised of
high resolution spectra previously acquired at the McDonald, Lick and Keck
Observatories. To enlarge our data pool, we acquired globular and open cluster
spectra from several other investigators. Data were analyzed using synthetic
spectra of the 6000 \AA Mn I triplet. Hyperfine structure parameters were
included in the synthetic spectra computations. Our analysis shows that for the
metallicity range $-0.7>$[Fe/H]$>$$-$2.7 stars of 19 globular clusters have a a
mean relative abundance of $<$[Mn/Fe]$>$= $-0.37\pm0.01$ ($\sigma$ = 0.10), a
value in agreement with that of the field stars: $<$[Mn/Fe]$>$= $-0.36\pm0.01$
($\sigma$ = 0.08). Despite the 2 orders of magnitude span in metallicity, the
$<$[Mn/Fe]$>$ ratio remains constant in both stellar populations. Our Mn
abundance data indicate that there is no appreciable variation in the relative
nucleosynthetic contribution from massive stars that undergo core-collapse
supernovae and thus, no significant change of the associated initial mass
function in the specified metallicity range.


title:
Japanese Virtual Observatory (JVO) as an advanced astronomical research
  enviroment

abstract:
  We present the design and implementation of the Japanese Virtual Observatory
(JVO) system. JVO is a portal site to various kinds of astronomical resources
distributed all over the world. We have developed five components for
constructing the portal: (1) registry, (2) data service, (3) workflow system,
(4) data analysis service (5) portal GUI. Registry services are used for
publishing and searching data services in the VO, and they are constructed
using an OAI-PMH metadata harvesting protocol and a SOAP web service protocol
so that VO standard architecture is applied. Data services are developed based
on the Astronomical Data Query Language (ADQL) which is an international VO
standard and an extension of the standard SQL. The toolkit for building the
ADQL-based service is released to the public on the JVO web site. The toolkit
also provides the protocol translation from a Simple Image Access Protocol
(SIAP) to ADQL protocol, so that both the VO standard service can be
constructed using our toolkit. In order to federate the distributed databases
and analysis services, we have designed a workflow language which is described
in XML and developed execution system of the workflow. We have succeeded to
connect to a hundred of data resources of the world as of April 2006. We have
applied this system to the study of QSO environment by federating a QSO
database, a Subaru Suprim-Cam database, and some analysis services such a
SExtractor and HyperZ web services. These experiences are described is this
paper.


title: Outflows driven by Giant Protoplanets

abstract:
  We investigate outflows driven by a giant protoplanet using three-dimensional
MHD nested grid simulations. We consider a local region around the protoplanet
in the protoplanetary disk, and calculate three models: (a) unmagnetized disk
model, (b) magnetized disk model having magnetic field azimuthally parallel to
the disk, and (c) magnetic field perpendicular to the disk. Outflows with
velocities, at least, 10 km/s are driven by the protoplanets in both magnetized
disk models, while outflow does not appear in unmagnetized disk model.
Tube-like outflows along the azimuthal direction of the protoplanetary disk
appear in model with magnetic field being parallel to the disk. In this model,
the magnetically dominated regions (i.e., density gap) are clearly contrasted
from other regions and spiral waves appear near the protoplanet. On the other
hand, in model with magnetic field being perpendicular to the disk, outflows
are driven by a protoplanet with cone-like structure just as seen in the
outflow driven by a protostar. Magnetic field lines are strongly twisted near
the protoplanet and the outflows have well-collimated structures in this
model.These outflows can be landmarks for searching exo-protoplanets in their
formation stages. Our results indicate that the accretion rate onto the
protoplanet tend to have a larger value than that expected from previous
hydrodynamical calculations, since a fraction of the angular momentum of
circum-planetary disk is removed by outflows, enhanced non-axisymmetric
patterns caused by magnetic field, and magnetic braking. Possible implications
for observation are also briefly discussed.


title: Mid-IR selected Quasars in the First Look Survey

abstract:
  We present a preliminary investigation of the spectral energy distributions
(SEDs), and star-formation properties of a sample of Mid-IR selected Quasars.
The mid-infrared SEDs of our objects are consistent with that expected from
clumpy torus models. At longer wavelengths, the radio to infrared ratios of
several objects are consistent with those of star-forming galaxies.


title: Bigradient Phase Referencing

abstract:
  We propose bigradient phase referencing (BPR), a new radio-observation
technique, and report its performance using the Japanese
very-long-baseline-interferometry network (JVN). In this method, a weak source
is detected by phase-referencing using a primary calibrator, in order to play a
role as a secondary calibrator for phase-referencing to a weak target. We will
be given the opportunity to select a calibrator from lots of milli-Jansky
sources, one of which may be located at the position closer to the target. With
such a smaller separation, high-quality phase-referencing can be achieved.
Furthermore, a subsequent more-sophisticated calibration can relocate array's
focus to a hypothetical point much closer to the target; a higher quality of
phase referencing is available. Our demonstrative observations with strong
radio sources have proved the capabilities of BPR in terms of image dynamic
ranges and astrometric reproducibility. The image dynamic range on a target has
been improved with a factor of about six compared to that of normal
phase-referencing; the resultant position difference of target's emission
between two epochs was only 62+-50 micro-arcsecond, even with less than 2300-km
baselines at 8.4 GHz and fast-switching of a target-calibrator pair of a
2.1-degree separation.


title:
Optical spectroscopy of (candidate) ultra-compact X-ray binaries:
  constraints on the composition of the donor stars

abstract:
  We present optical spectroscopy of several (candidate) ultra-compact X-ray
binaries (UCXBs) obtained with the ESO VLT and Gemini-North telescopes. In only
one of five observed UCXB candidates did we find evidence for H in its spectrum
(4U 1556-60). For XB 1905+00 the optical counterpart is not detected. For the
known UCXBs 4U 1626-67 and XB 1916-05 we find spectra consistent with a C/O and
a He/N accretion disc respectively, the latter is the first optical spectrum of
a He-rich donor in an UCXB. Interestingly, the C/O spectrum of 4U 1626-67 shows
both similarities as well as marked differences from the optical C/O spectrum
of 4U 0614+09. We obtained phase resolved spectroscopy of 4U 0614+09 and the 44
min transient XTE J0929-314. In neither object were we able to detect clear
orbital periodicities, highlighting the difficulties of period determinations
in UCXBs. We reanalysed the spectra of XTE J0929-314 that were taken close to
the peak of its 2003 X-ray outburst and do not confirm the detection of Halpha
emission as was claimed in the literature. The peak spectra do show strong C or
N emission around 4640A, as has also been detected in other UCXBs. We discuss
the implications of our findings for our understanding of the formation of
UCXBs and the Galactic population of UCXBs. At the moment all studied systems
are consistent with having white dwarf donors, the majority being C/O rich.


title:
Gravitational Clustering in Redshift Space: Non-Gaussian Tail of the
  Cosmological Density Distribution Function

abstract:
  We study the non-Gaussian tail of the probability distribution function of
density in cosmological N-Body simulations for a variety of initial conditions.
We compare the behaviour of the non-Gaussian tail in the real space with that
in the redshift space. The form of the PDF in redshift space is of great
significance as galaxy surveys probe this and not the real space analogue
predicted using theoretical models. We model the non-Gaussian tail using the
halo model. In the weakly non-linear regime the moments of counts in cells in
the redshift space approach the values expected from perturbation theory for
moments in real space. We show that redshift space distortions in the
non-linear regime dominate over signatures of initial conditions or the
cosmological background. We illustrate this using Skewness and higher moments
of counts in cells, as well as using the form of the non-Gaussian tail of the
distribution function. We find that at scales smaller than the scale of
non-linearity the differences in Skewness, etc. for different models are very
small compared to the corresponding differences in real space. We show that
bias also leads to smaller values of higher moments, but the redshift space
distortions are typically the dominant effect.


title:
Internal dynamics of the massive cluster Abell 697: a multiwavelength
  analysis

abstract:
  We conduct an intensive study of the rich, X-ray luminous, and hot galaxy
cluster Abell 697 (at z=0.282), likely containing a diffuse radio emission, to
determine its dynamical status. Our analysis is based on new spectroscopic data
obtained at the TNG telescope for 93 galaxies and on new photometric data
obtained at the INT telescope. We combine galaxy velocity and position
information to select 68 cluster members, determine global dynamical
properties, and detect possible substructures. The investigation of the
dynamical status is also performed by using X-ray data stored in the Chandra
archive. We compute the line-of-sight (LOS) velocity dispersion of galaxies,
sigma_v=1334 km s^-1, in agreement with the high average X-ray temperature
T_X=10.2 keV recovered from Chandra data. Assuming that the cluster is in
dynamical equilibrium and mass follows the galaxy distribution, we find that
A697 is a very massive cluster obtaining M(<R_max=0.75 Mpc h^-1)=9.5x10^14
solar masses h^-1 and M(<R_vir=3.85 Mpc h^-1)=4.5x10^15 solar masses h^-1 for
the region well sampled by the spectroscopic data and for the entire virialized
region, respectively. Further investigations find that A697 is not fully
relaxed, as shown by the non Gaussianity of the velocity distribution, the
elongation of the X-ray emission, and the presence of small-size substructures
in the central region. Our results suggest that we are looking at a cluster
undergone to a complex cluster merger occurring roughly mainly along the LOS,
with a transverse component in the SSE-NNW direction. Our study supports the
hypothesis of a relation between extended radio emission and merging phenomena.


title:
Simultaneous X-ray and optical observations of S5 0716+714 after the
  outburst of March 2004

abstract:
  At the end of March 2004, the blazar S5 0716+714 underwent an optical
outburst that prompted for quasi-simultaneous target-of-opportunity
observations with the INTEGRAL and XMM-Newton satellites. In this paper, we
report the results of the XMM-Newton and INTEGRAL OMC data analysis. The X-ray
spectrum is well-represented by a concave broken power-law model, with the
break at about 2 keV. In the framework of the synchrotron self-Compton model,
the softer part of the spectrum, which is described by a power law of index
$\alpha \simeq 1.8$ ($f_\nu \propto \nu^{-\alpha}$), is probably due to
synchrotron emission, while the harder part of the spectrum, which has $\alpha
\simeq 1$, is due to inverse Compton emission. The blazar shows the long and
short-term variability typical of low-frequency peaked BL Lac (LBL): the former
is manifested by a gradual decrease in the optical flux from the peak as
observed by ground telescopes at the end of March 2004, while the latter is
characterized by soft X-ray and optical flares on time scales from a few
thousand seconds to few hours. We can follow spectral variations on sub-hour
time scales and study their correlation with the flux variability. We find
evidence that the peak energy of the time-resolved spectra is increasing with
flux. The modeling of the spectral energy distribution compared with archival
observations suggests that the long-term variability (from outburst to
quiescence or viceversa) could be due to a change in the injected power, while
the short-term variability (flares) could be explained with changes in the
slope of the distribution of the electrons.


title:
Gaussian Decomposition of HI Surveys - II. Separation of Problematic
  Gaussians

abstract:
  We have analyzed the Gaussian decomposition of the Leiden/Dwingeloo Survey
(LDS) of galactic neutral hydrogen for the presence of Gaussians probably not
directly related to galactic HI emission. It is demonstrated that at least
three classes of such components can be distinguished. The narrowest Gaussians
mostly represent stronger random noise peaks in profiles and some still
uncorrected radio-interferences. Many of slightly wider weak Gaussians are
caused by increased uncertainties near the profile edges and with the still
increasing width the baseline problems become dominating among weak components.
Statistical criteria are given for separation of the parameter space regions,
most likely populated with the problematic components from those where the
Gaussians are with higher probability describing the actual Milky Way HI
emission. The same analysis is applied to the Leiden/Argentina/Bonn survey
(LAB). It is demonstrated that the selection criteria for dividing the
parameter space are to a great extent independent of the particular survey in
use. The presence of the baseline problems in the LDS is indicated by the
peculiarities of the distribution of the widest Gaussians in the sky. A similar
plot for the northern part of the LAB demonstrates considerably lower numbers
of spurious components, but there are still problems with the southern part of
the LAB. The strange characteristics of the observational noise in the southern
part of the LAB are pointed out.


title: Coupled Quintessence and CMB

abstract:
  We revise the stability of the tracking solutions and briefly review the
potentials of quintessence models. We discuss the evolution of linear
perturbations for $V(\phi) = V_{0} \exp(\lambda \phi^2/2)$ potential in which
the scalar field is non-minimally coupled to cold dark matter. We consider the
effects of this coupling on both cosmic microwave background temperature
anisotropies and matter perturbations. We find that the phenomenology of this
model is consistent with current observations up to the coupling power $n_{c}
\leq 0.01$ while adopting the current parameters measured by WMAP,
$\Omega_{\phi}^{(0)}=0.76$, $\Omega_{cdm}^{(0)}=0.191$,
$\Omega_{b}^{(0)}=0.049$, and $h=0.70$. Upcoming cosmic microwave background
observations continuing to focus on resolving the higher peaks may put strong
constraints on the strength of the coupling.


title: A detailed modelling of the chemically rich clumps along the CB3 outflow

abstract:
  In order to investigate the origin and the structure of the low velocity,
chemically rich clumps observed along the lobes of low- and intermediate-mass
outflows, we construct a detailed model of the S1 clump along the CB3 outflow.
We use a time-dependent chemical model coupled with a radiative transfer model
to reproduce the observed line profile for a direct comparison with previous
observations of this clump. We find that the simultaneous fitting of multiple
species and transitions is a powerful tool in constraining the physical
parameters of the gas. Different scenarios for the clump formation have been
investigated. The models that better reproduce all the observed lines are those
where the clump is formed, at least partially, before the advent of the
outflow; with the advent of the outflow the clump undergoes a short period of
non-dissociative shock and the consequent release of the icy mantle together
with the high temperature chemistry leads to the observed chemical enrichment.
Our results also suggest the presence of substructure within the clump: a more
extended component traced by CS, SO and the lower energy transitions (3_k-2_k
and 2_k-1_k) of CH_3OH, and a more compact component traced by H_2CO, SO_2 and
the higher energy transitions (5_k-4_k) of CH_3OH.


title:
Warm Dust and Spatially Variable PAH Emission in the Dwarf Starburst
  Galaxy NGC 1705

abstract:
  We present Spitzer observations of the dwarf starburst galaxy NGC 1705
obtained as part of SINGS. The galaxy morphology is very different shortward
and longward of ~5 microns: short-wavelength imaging shows an underlying red
stellar population, with the central super star cluster (SSC) dominating the
luminosity; longer-wavelength data reveals warm dust emission arising from two
off-nuclear regions offset by ~250 pc from the SSC. These regions show little
extinction at optical wavelengths. The galaxy has a relatively low global dust
mass (~2E5 solar masses, implying a global dust-to-gas mass ratio ~2--4 times
lower than the Milky Way average). The off-nuclear dust emission appears to be
powered by photons from the same stellar population responsible for the
excitation of the observed H Alpha emission; these photons are unassociated
with the SSC (though a contribution from embedded sources to the IR luminosity
of the off-nuclear regions cannot be ruled out). Low-resolution IRS
spectroscopy shows moderate-strength PAH emission in the 11.3 micron band in
the eastern peak; no PAH emission is detected in the SSC or the western dust
emission complex. There is significant diffuse 8 micron emission after scaling
and subtracting shorter wavelength data; the spatially variable PAH emission
strengths revealed by the IRS data suggest caution in the interpretation of
diffuse 8 micron emission as arising from PAH carriers alone. The metallicity
of NGC 1705 falls at the transition level of 35% solar found by Engelbracht and
collaborators; the fact that a system at this metallicity shows spatially
variable PAH emission demonstrates the complexity of interpreting diffuse 8
micron emission. A radio continuum non-detection, NGC 1705 deviates
significantly from the canonical far-IR vs. radio correlation. (Abridged)


title: A periodically active pulsar giving insight into magnetospheric physics

abstract:
  PSR B1931+24 (J1933+2421) behaves as an ordinary isolated radio pulsar during
active phases that are 5-10 days long. However, the radio emission switches off
in less than 10 seconds and remains undetectable for the next 25-35 days, then
it switches on again. This pattern repeats quasi-periodically. The origin of
this behaviour is unclear. Even more remarkably, the pulsar rotation slows down
50% faster when it is on than when it is off. This indicates a massive increase
in magnetospheric currents when the pulsar switches on, proving that pulsar
wind plays a substantial role in pulsar spin-down. This allows us, for the
first time, to estimate the currents in a pulsar magnetospheric during the
occurrence of radio emission.


title:
Global properties of the HI high velocity sky, a statistical
  investigation based on the LAB survey

abstract:
  We study the properties of all major HVC complexes from a sample compiled
1991 by Wakker & van Woerden (WvW). We use the Leiden/Argentine/Bonn all sky
21-cm line survey and decompose the profiles into Gaussian components. We find
a well defined multi-component structure for most of the HVC complexes. The
cold HVC phase has lines with typical velocity dispersions of sigma = 3 km/s
and exists only within more extended broad line regions, typically with sigma =
12 km/s. The motions of the cores relative to the envelopes are characterized
by Mach numbers M = 1.5. The center velocities of the cores within a HVC
complex have typical dispersions of 20 km/s. Remarkable is the well defined
two-component structure for some prominent HVC complexes in the outskirts of
the Milky Way: Complex H, the Magellanic Stream and the Leading Arm. There
might be some indications for an interaction between HVCs and disk gas at
intermediate velocities. This is possible for complex H, M, C, WB, WD, WE, WC,
R, G, GCP, and OA, but not for complex A, MS, ACVHV, EN, WA, and P.
Conclusions: The line widths, determined by us, imply that estimates of HVC
masses, as far as derived from the WvW database, need to be scaled up by a
factor 1.4. Correspondingly, guesses for the external pressure of a confining
coronal gas need to be revised upward by a factor of 2. The HVC multi-phase
structure implies in general that currently the halo pressure is significantly
underestimated. In consequence, the HVC multi-phase structure may indicate that
most of the complexes are circum-galactic. HVCs have turbulent energy densities
which are an order of magnitude larger than that of comparable clumps in the
Galactic disk.


title:
A method of measurement of extragalactic magnetic fields by TeV gamma
  ray telescopes

abstract:
  We propose a method of measurement of extragalactic magnetic fields in
observations of TeV gamma-rays from distant blazars. Multi-TeV gamma-rays are
emitted by these sources in narrow jet with opening angle of few degrees. These
primary gamma-rays interact with the infrared photon background producing
secondary electrons and positrons, which can be just slightly deflected by
extragalactic magnetic fields before they emit secondary gamma-rays via inverse
Compton scattering of cosmic microwave background photons. Secondary gamma-rays
emitted toward an observer on the Earth can be detected as extended emission
around initially point source. Energy dependent angular size of extended
emission is related to the value of extragalactic magnetic field along the line
of sight. Small magnetic fields B < 10^{-12} G in the voids of the large scale
structure can be measured in this way.


title: An IR study of pure and ion irradiated frozen formamide

abstract:
  Context. The chemical evolution of formamide (HCONH2), a molecule of
astrobiological interest that has been tentatively identified in interstellar
ices and in cometary coma, has been studied in laboratory under simulated
astrophysical conditions such as ion irradiation at low temperature.
  Aims. To evaluate the abundances of formamide observed in space or in
laboratory, the integrated absorbances for all the principal IR features of
frozen amorphous pure formamide deposited at 20 K were measured. Further
evidence that energetic processing of ices occurring in space is extremely
relevant both to astrochemistry and to astrobiology has been found, showing
that new molecular species are synthesized by ion irradiation at a low
temperature.
  Methods. Pure formamide were deposited at 20 K and IR transmission spectra
measured for different ice thicknesses. The ice thickness was derived by
looking at the interference pattern (intensity versus time) of a He-Ne laser
beam reflected at an angle of 45 deg by the vacuum-film and film-substrate
interfaces. Samples of formamide ice were irradiated with 200 keV H+ ions and
IR spectra recorded at different ion fluences.
  Results. New molecules were synthesized among which are CO, CO2, N2O,
isocyanic acid (HNCO), and ammonium cyanate (NH4+OCN-). Some of these species
remain stable after warming up to room temperature.


title:
Solar ions in the heliosheath: a possible new source of heavy neutral
  atoms

abstract:
  We show that multiply ionized coronal C, N, O, Mg, Si, S ions carried by the
solar wind and neutralized by consecutive electron captures from neutral
interstellar atoms constitute an important new source of neutral atoms in the
inner heliosheath, with energies up to ~ 1 keV/n. In the model we developed,
the heavy ions are treated as test particles carried by hydrodynamic plasma
flow (with a Monte-Carlo description of interstellar neutrals) and undergoing
all relevant atomic processes determining the evolution of all charge-states of
considered species (radiative and dielectronic recombination, charge exchange,
photo-, and electron impact ionization). The total strength of the source is
from ~10^6 g/s for S to ~10^8 g/s for O, deposited as neutrals below the
heliopause. These atoms should provide, as they drift to supersonic wind
region, important sources of PUIs and eventually ACRs, especially for species
that are excluded from entering the heliosphere because of their ionization in
the LISM. The expected corresponding ENA fluxes at 1 AU are in the range 10^-4
- 10^0 at./(cm^2 s sr), depending on the species and direction (Table 2).


title:
The FSVS Cluster Catalogue: Galaxy Clusters and Groups in the Faint Sky
  Variability Survey

abstract:
  We describe a large sample of 598 galaxy clusters and rich groups discovered
in the data of the Faint Sky Variability Survey. The clusters have been
identified using a fully automated, semi-parametric technique based on a
maximum likelihood approach applied to Voronoi tessellation, and enhanced by
colour discrimination. The sample covers a wide range of richness, has a
density of ~28 clusters per sqdeg, and spans a range of estimated redshifts of
0.05 < z < 0.9 with mean <z> = 0.345. Assuming the presence of a cluster red
sequence, the uncertainty of the estimated cluster redshifts is assessed to be
\~0.03. Containing over 100 clusters with z > 0.6, the catalogue contributes
substantially to the current total of optically-selected, intermediate-redshift
clusters, and complements the existing, usually X-ray selected, samples. The
FSVS fields are accessible for observation throughout the whole year, making
them particularly suited for large follow-up programmes. The construction of
this FSVS Cluster Catalogue completes a fundamental component of our continuing
programmes to investigate the environments of quasars and the chemical
evolution of galaxies. We publish here the list of all clusters with their
basic parameters, and discuss some illustrative examples in more detail. The
full FSVS Cluster Catalogue, together with images and lists of member galaxies
etc., will be issued as part of the ``NOAO data products'', and accessible at
http://www.noao.edu/dpp/. We describe the format of these data and access to
them.


title: Non-gaussianity for a Two Component Hybrid Model of Inflation

abstract:
  We consider a two component hybrid inflation model, in which two fields drive
inflation. Our results show that this model generates an observable
non-gaussian contribution to the curvature spectrum, within the limits allowed
by the recent WMAP year 3 data. We show that if one field has a mass less than
zero, and an initial field value less than 0.06Mpl while the other field has a
mass greater than zero, and initial field value ranging between 0.5Mpl and Mpl
then the non-gaussianity is observable with 1<fnl<1.5, but that fnl becomes
much less than the observable limit should we take both masses to have the same
sign, or if we loosened the constraints on the initial field values.


title: Near-IR spectroscopy of OH/IR stars in the Galactic Centre

abstract:
  Context. Galactic Centre (GC) OH/IR stars can be, based on the expansion
velocities of their circumstellar shells, divided into two groups which are
kinematically different and therefore are believed to have evolved from
different stellar populations. Aims. To study the metallicity distribution of
the OH/IR stars population in the GC on basis of a theoretical relation between
EW(Na), EW(Ca) and EW(CO) and the metallicity. Methods. For 70 OH/IR stars in
the GC, we obtained near-IR spectra. The equivalent line widths of NaI, CaI,
12CO(2,0) and the curvature of the spectrum around 1.6 micron due to water
absorption are determined. Results. The near-IR spectrum of OH/IR stars is
influenced by several physical processes. OH/IR stars are variable stars
suffering high mass-loss rates. The dust that is formed around the stars
strongly influences the near-IR spectra and reduces the equivalent line widths
of NaI, CaI. A similar effect is caused by the water content in the outer
atmosphere of the OH/IR star. Because of these effects, it is not possible with
our low resolution near-infrared spectroscopy to determine the metallicities of
these stars.


title: Interaction of a Moreton/EIT wave and a coronal hole

abstract:
  We report high-cadence H-alpha observations of a distinct Moreton wave
observed at Kanzelhoehe Solar Observatory associated with the 3B/X3.8 flare and
CME event of 2005 January 17. The Moreton wave can be identified in about 40
H-alpha frames over a period of 7 min. The EIT wave is observed in only one
frame but the derived propagation distance is close to that of the
simultaneously measured Moreton wave fronts indicating that they are closely
associated phenomena. The large angular extent of the Moreton wave allows us to
study the wave kinematics in different propagation directions with respect to
the location of a polar coronal hole (CH). In particular we find that the wave
segment whose propagation direction is perpendicular to the CH boundary
(``frontal encounter'') is stopped by the CH which is in accordance with
observations reported from EIT waves (Thompson et al. 1998). However, we also
find that at a tongue-shaped edge of the coronal hole, where the front
orientation is perpendicular to the CH boundary (the wave ``slides along'' the
boundary), the wave signatures can be found up to 100 Mm inside the CH. These
findings are briefly discussed in the frame of recent modeling results.


title: Polarimetric survey of asteroids with the Asiago telescope

abstract:
  We present the first results of an asteroid photo--polarimetry program
started at Asiago--Cima Ekar Observatory. The aim of our survey is to estimate
diversity in polarimetric properties of asteroids belonging to different
taxonomic and dynamical classes. The data were obtained with the polarization
analyser placed inside the Faint Object Spectrographic Camera (AFOSC) of the
1.8m telescope. This instrument allows simultaneous measurements of the two
first Stokes parameters without any lambda/2 retarding plate. Our survey began
in 2002, and up to now we have obtained data on a sample of 36 asteroids; most
of them are being investigated with the polarimetric technique for the first
time. Combining our data with those already available in literature, we present
an estimate of the inversion angle for 7 asteroids in this paper. Furthermore,
we present the polarimetric measurements of the rare asteroid classes belonging
to the A and D types and a detailed VRI observations at extremely small phase
angles of the low albedo asteroid 1021 Flammario


title: Star formation through gravitational collapse and competitive accretion

abstract:
  Competitive accretion, a process to explain the origin of the IMF, occurs
when stars in a common gravitational potential accrete from a distributed
gaseous component. We show that concerns recently raised on the efficiency of
competitive accretion are incorrect as they use globally averaged properties
which are inappropriate for the detailed physics of a forming stellar cluster.
A full treatment requires a realistic treatment of the cluster potential, the
distribution of turbulent velocities and gas densities. Accreting gas does not
travel at the global virial velocity of the system due to the
velocity-sizescale relation inherent in turbulent gas and due to the lower
velocity dispersion of small-N clusters in which much of the accretion occurs.
Stars located in the gas-rich centres of such systems initially accrete from
low relative velocity gas attaining larger masses before needing to accrete the
higher velocity gas. Stars not in the centres of such potentials, or that enter
the cluster later when the velocity dispersion is higher, do not accrete
significantly and thus retain their low-masses. In competitive accretion, most
stars do not continue to accrete significantly such that their masses are set
from the fragmentation process. It is the few stars which continue to accrete
that become higher-mass stars. Competitive accretion is therefore likely to be
responsible for the formation of higher-mass stars and can explain the mass
distribution, mass segregation and binary frequency of these stars. Global
kinematics of competitive accretion models include large-scale mass infall,
with mean inflow velocities of order 0.5 km/s at scales of 0.5 pc, but infall
signatures are likely to be confused by the large tangential velocities and the
velocity dispersion present.


title: Extending the WMAP Bound on the Size of the Universe

abstract:
  Clues to the shape of our Universe can be found by searching the CMB for
matching circles of temperature patterns. A full sky search of the CMB, mapped
extremely accurately by NASA's WMAP satellite, returned no detection of such
matching circles and placed a lower bound on the size of the Universe at 24
Gpc. This lower bound can be extended by optimally filtering the WMAP power
spectrum. More stringent bounds can be placed on specific candidate topologies
by using a a combination statistic. We use optimal filtering and the
combination statistic to rule out the infamous "soccer ball universe'' model.


title:
Elemental Abundance Measurements in Low-redshift Damped Lyman Alpha
  Absorbers

abstract:
  We present elemental abundance measurements for 9 damped Ly-alpha systems
(DLAs) and 1 sub-DLA at 0.1 < z < 1.5 from recent observations with the
Multiple Mirror Telescope. Most of these absorbers are found to be metal-poor,
while 2 are found to have ~ 30-50 solar metallicities. Combining our data with
other data from the literature, we find that the systems with higher [Zn/H]
also have stronger depletion as measured by [Cr/Zn] and [Fe/Zn]. The
relationship between the metallicity and H I column density is also
investigated. Together with our previous MMT survey (Khare et al. 2004) we have
discovered 2 of the 4 known absorbers at z < 1.5 that lie above (although near)
the "obscuration threshold". This appears to be a result of selecting absorbers
with strong metal lines in our sample. It would be interesting to find other
similar systems by observing a larger sample and study how much such systems
contribute to the cosmic budget of metals. Finally, an analysis of the N(H
I)-weighted mean metallicity vs. redshift for our sample combined with data
from the literature supports previous conclusions that the N(H I)-weighted mean
global DLA metallicity rises slowly at best and falls short of solar levels by
a factor of > 4 even at z=0.


title:
Swift observations of the 2006 outburst of the recurrent nova RS
  Ophiuchi: I. Early X-ray emission from the shocked ejecta and red giant wind

abstract:
  RS Ophiuchi began its latest outburst on 2006 February 12. Previous outbursts
have indicated that high velocity ejecta interact with a pre-existing red giant
wind, setting up shock systems analogous to those seen in Supernova Remnants.
However, in the previous outburst in 1985, X-ray observations did not commence
until 55 days after the initial explosion. Here we report on Swift observations
covering the first month of the 2006 outburst with the Burst Alert (BAT) and
X-ray Telescope (XRT) instruments. RS Oph was clearly detected in the BAT 14-25
keV band from t=0 to $t\sim6$ days. XRT observationsfrom 0.3-10 keV, started at
3.17 days after outburst. The rapidly evolving XRT spectra clearly show the
presence of both line and continuum emission which can be fitted by thermal
emission from hot gas whose characteristic temperature, overlying absorbing
column, $[N_H]_W$, and resulting unabsorbed total flux decline monotonically
after the first few days. Derived shock velocities are in good agreement with
those found from observations at other wavelengths. Similarly, $[N_H]_W$ is in
accord with that expected from the red giant wind ahead of the forward shock.
We confirm the basic models of the 1985 outburst and conclude that standard
Phase I remnant evolution terminated by $t\sim10$ days and the remnant then
rapidly evolved to display behaviour characteristic of Phase III. Around t=26
days however, a new, luminous and highly variable soft X-ray source began to
appear whose origin will be explored in a subsequent paper.


title:
Mass segregation in rich LMC clusters from modelling of deep HST
  colour-magnitude diagrams

abstract:
  We used the deep colour-magnitude diagrams (CMDs) of five rich LMC clusters
(NGC1805, 1818, 1831, 1868, and Hodge14) observed with HST/WFPC2 to derive
their present day mass function (PDMF) and its variation with position within
the cluster. The PDMF was parameterized as a power law in the available
main-sequence mass range of each cluster, typically 0.9 <~ m/M_sun <~ 2.5; its
slope was determined at different positions spanning from the very centre out
to several core radii. The CMDs in the central regions of the clusters were
carefully studied earlier, resulting in accurate age, metallicity, distance
modulus, and reddening values. The slope alpha (where Salpeter is 2.35) was
determined in annuli by following two distinct methods: 1) a power law fit to
the PDMF obtained from the systemic luminosity function (LF); 2) a statistical
comparison between observed and model CMDs. In all clusters, significant mass
segregation is found from the positional dependence of the PDMF slope: alpha <~
1.8 for R <= 1.0 R_core and alpha ~ Salpeter inside R=2~3 R_core (except for
Hodge 14, where alpha ~ Salpeter for R ~ 4 R_core). The results are robust in
the sense that they hold true for both methods used. The CMD method reveals
that unresolved binaries flatten the PDMF obtained form the systemic LF, but
this effect is smaller than the uncertainties in the alpha determination. For
each cluster we estimated dynamical ages inside the core and for the entire
system. In both cases we found a trend in the sense that older clusters have
flatter PDMF, consistent with a dynamical mass segregation and stellar
evaporation.


title: A Two-Zone Model for Type I X-ray Bursts on Accreting Neutron Stars

abstract:
  We construct a two-zone model to describe H and He burning on the surface of
an accreting neutron star and use it to study the triggering of type I X-ray
bursts. Although highly simplified, the model reproduces all of the bursting
regimes seen in the more complete global linear stability analysis of Narayan &
Heyl (2003), including the regime of delayed mixed bursts. The results are also
consistent with observations of type I X-ray bursts. At accretion rates Mdot <
0.1 Mdot_Edd, thermonuclear He burning via the well-known thin-shell thermal
instability triggers bursts. As Mdot increases, however, the trigger mechanism
evolves from the fast thermal instability to a slowly growing overstability
involving both H and He burning. The competition between nuclear heating via
the beta-limited CNO cycle and the triple-alpha process on the one hand, and
radiative cooling via photon diffusion and emission on the other hand, drives
oscillations with a period approximately equal to the H-burning timescale. If
these oscillations grow, the gradually rising temperature at the base of the
helium layer eventually provokes a thin-shell thermal instability and hence a
delayed mixed burst. For Mdot > 0.25 Mdot_Edd, there is no instability or
overstability, and there are no bursts. Nearly all other theoretical models
predict that bursts should occur for all Mdot < Mdot_Edd, in conflict with both
our results and observations. We suggest that this discrepancy arises from the
assumed strength of the hot CNO cycle breakout reaction 15O(alpha,gamma)19Ne in
these other models. That observations agree much better with the results of
Narayan & Heyl and our two-zone model, both of which neglect breakout
reactions, may imply that the true 15O(alpha,gamma)19Ne cross section is much
smaller than assumed in previous investigations.


title:
The new sample of giant radio sources II. Update of optical
  counterparts, further spectroscopy of identified faint host galaxies,
  high-frequency radio maps, and polarisation properties of the sources

abstract:
  Our sample of giant radio-source candidates, published in Paper I (Machalski
et al. 2001), is updated and supplemented with further radio and optical data.
In this paper we present: (i) newly detected host galaxies, their photometric
magnitude, and redshift estimate for the sample sources not identified yet,
(ii) optical spectra and spectroscopic redshift for the host galaxies fainter
than about 18.5 mag taken with the Apache Point Observatory 3.5m telescope, and
(iii) the VLA 4.9 GHz total-intensity and polarised-intensity radio maps of the
sample members. In a few cases they reveal extremely faint radio cores
undetected before, which confirm the previously uncertain optical
identifications. The radio maps are analysed and the polarisation properties of
the sample sources summarised. A comparison of our updated sample with three
samples published by other authors implies that all these four samples probe
the same part of the population of extragalactic radio sources. There is no
significant difference between the distributions of intrinsic size and radio
power among these samples. The median redshift of 0.38 +/- 0.07 in our sample
is the highest among the corresponding values in the four samples, indicating
that the angular size and flux-density limits in our sample, lower than those
for the other three samples, result in effective detections of more distant,
giant-size galaxies compared to those detected in the other samples. This
sample and a comparison sample of `normal'-size radio galaxies will be used in
Paper III (Machalski & Jamrozy 2006) to investigate of a number of trends and
correlations in the entire data.


title: A Bayesian model selection analysis of WMAP3

abstract:
  We present a Bayesian model selection analysis of WMAP3 data using our code
CosmoNest. We focus on the density perturbation spectral index $n_S$ and the
tensor-to-scalar ratio $r$, which define the plane of slow-roll inflationary
models. We find that while the Bayesian evidence supports the conclusion that
$n_S \neq 1$, the data are not yet powerful enough to do so at a strong or
decisive level. If tensors are assumed absent, the current odds are
approximately 8 to 1 in favour of $n_S \neq 1$ under our assumptions, when
WMAP3 data is used together with external data sets. WMAP3 data on its own is
unable to distinguish between the two models. Further, inclusion of $r$ as a
parameter weakens the conclusion against the Harrison-Zel'dovich case (n_S = 1,
r=0), albeit in a prior-dependent way. In appendices we describe the CosmoNest
code in detail, noting its ability to supply posterior samples as well as to
accurately compute the Bayesian evidence. We make a first public release of
CosmoNest, now available at http://www.cosmonest.org.


title:
Model selection forecasts for the spectral index from the Planck
  satellite

abstract:
  The recent WMAP3 results have placed measurements of the spectral index n_S
in an interesting position. While parameter estimation techniques indicate that
the Harrison-Zel'dovich spectrum n_S=1 is strongly excluded (in the absence of
tensor perturbations), Bayesian model selection techniques reveal that the case
against n_S=1 is not yet conclusive. In this paper, we forecast the ability of
the Planck satellite mission to use Bayesian model selection to convincingly
exclude (or favour) the Harrison-Zel'dovich model.


title: GRB 060313: A New Paradigm for Short-Hard Bursts?

abstract:
  We report the simultaneous observations of the prompt emission in the
gamma-ray and hard X-ray bands by the Swift-BAT and the KONUS-Wind instruments
of the short-hard burst, GRB 060313. The observations reveal multiple peaks in
both the gamma-ray and hard X-ray bands suggesting a highly variable outflow
from the central explosion. We also describe the early-time observations of the
X-ray and UV/Optical afterglows by the Swift XRT and UVOT instruments. The
combination of the X-ray and UV/Optical observations provide the most
comprehensive lightcurves to date of a short-hard burst at such an early epoch.
The afterglows exhibit complex structure with different decay indices and
flaring. This behavior can be explained by the combination of a structured jet,
radiative loss of energy, and decreasing microphysics parameters occurring in a
circum-burst medium with densities varying by a factor of approximately two on
a length scale of 10^17 cm. These density variations are normally associated
with the environment of a massive star and inhomogeneities in its windy medium.
However, the mean density of the observed medium (n approximately 10^−4
cm^3) is much less than that expected for a massive star. Although the collapse
of a massive star as the origin of GRB 060313 is unlikely, the merger of a
compact binary also poses problems for explaining the behavior of this burst.
Two possible suggestions for explaining this scenario are: some short bursts
may arise from a mechanism that does not invoke the conventional compact binary
model, or soft late-time central engine activity is producing UV/optical but no
X-ray flaring.


title: The Central Regions of M31 in the 3 - 5 micron Wavelength Region

abstract:
  Images obtained with NIRI on the Gemini North telescope are used to
investigate the photometric properties of the central regions of M31 in the 3 -
5 micron wavelength range. The light distribution in the central arcsecond
differs from what is seen in the near-infrared in the sense that the difference
in peak brigh tness between P1 and P2 is larger in M' than in K'; no obvious
signature of P3 is dete cted in M'. These results can be explained if there is
a source of emission that contributes ~ 20% of the peak M' light of P1 and has
an effective temperature of no more than a few hundred K that is located
between P1 and P2. Based on the red K-M' color of this source, it is suggested
that the emission originates in a circumstellar dust shell surrounding a single
bright AGB star. A similar bright source that is ~ 8 arcsec from the center of
the galaxy is also detected in M'. Finally, the (L', K-L') color-magnitude
diagram of unblended stars shows a domin ant AGB population with photometric
characteristics that are similar to those of the most luminous M giants in the
Galactic bulge.


title: Predicting the Starquakes in PSR J0537-6910

abstract:
  We report on more than 7 years of monitoring of PSR J0537-6910, the 16 ms
pulsar in the Large Magellanic Cloud, using data acquired with the RXTE. During
this campaign the pulsar experienced 23 sudden increases in frequency
(``glitches'') amounting to a total gain of over six ppm of rotation frequency
superposed on its gradual spindown of d(nu)/d(t) = -2e-10 Hz/s. The time
interval from one glitch to the next obeys a strong linear correlation to the
amplitude of the first glitch, with a mean slope of about 400 days ppm (6.5
days per uHz), such that these intervals can be predicted to within a few days,
an accuracy which has never before been seen in any other pulsar. There appears
to be an upper limit of ~40 uHz for the size of glitches in_all_ pulsars, with
the 1999 April glitch of J0537 as the largest so far. The change in the
spindown of J0537 across the glitches, Delta(d(nu)/d(t)), appears to have the
same hard lower limit of -1.5e-13 Hz/s, as, again, that observed in all other
pulsars. The spindown continues to increase in the long term,
d(d(nu)/d(t))/d(t) = -1e-21 Hz/s/s, and thus the timing age of J0537 (-0.5 nu
d(nu)/d(t)) continues to decrease at a rate of nearly one year every year,
consistent with movement of its magnetic moment away from its rotational axis
by one radian every 10,000 years, or about one meter per year. J0537 was likely
to have been born as a nearly-aligned rotator spinning at 75-80 Hz, with a
|d(nu)/d(t)| considerably smaller than its current value of 2e-10 Hz/s. The
pulse profile of J0537 consists of a single pulse which is found to be flat at
its peak for at least 0.02 cycles.


title: Simulations of globular clusters merging in galactic nuclear regions

abstract:
  We present the results of detailed N-body simulations regarding the
interaction of four massive globular clusters in the central region of a
triaxial galaxy. The systems undergo a full merging event, producing a sort of
'Super Star Cluster' (SSC) whose features are close to those of a superposition
of the individual initial mergers. In contrast with other similar simulations,
the resulting SSC structural parameters are located along the observed scaling
relations of globular clusters. These findings seem to support the idea that a
massive SSC may have formed in early phases of the mother galaxy evolution and
contributed to the growth of a massive nucleus.


title:
The galaxy cluster X-ray luminosity--gravitational mass relation in the
  light of the WMAP 3rd year data

abstract:
  The 3rd year WMAP results mark a shift in best fit values of cosmological
parameters compared to the 1st year data and the concordance cosmological
model. We test the consistency of the new results with previous constraints on
cosmological parameters from the HIFLUGCS galaxy cluster sample and the impact
of this shift on the X-ray luminosity-gravitational mass relation. The measured
X-ray luminosity function combined with the observed luminosity-mass relation
are compared to mass functions predicted for given cosmological parameter
values. The luminosity function and luminosity-mass relation derived previously
from HIFLUGCS are in perfect agreement with mass functions predicted using the
best fit parameter values from the 3rd year WMAP data (OmegaM=0.238,
sigma8=0.74) and inconsistent with the concordance cosmological model
(OmegaM=0.3, sigma8=0.9), assuming a flat Universe. Trying to force consistency
with the concordance model requires artificially decreasing the normalization
of the luminosity-mass relation by a factor of 2. The shift in best fit values
for OmegaM and sigma8 has a significant impact on predictions of cluster
abundances. The new WMAP results are now in perfect agreement with previous
results on the OmegaM-sigma8 relation determined from the mass function of
HIFLUGCS clusters and other X-ray cluster samples (the ``low cluster
normalization''). We conclude that - unless the true values of OmegaM and
sigma8 differ significantly from the 3rd year WMAP results - the
luminosity-mass relation is well described by their previous determination from
X-ray observations of clusters, with a conservative upper limit on the bias
factor of 1.5. These conclusions are currently being tested in a complete
follow-up program of all HIFLUGCS clusters with Chandra and XMM-Newton.


title: Dark viscous fluid described by a unified equation of state in cosmology

abstract:
  We generalize the $\Lambda$CDM model by introducing a unified EOS to describe
the Universe contents modeled as dark viscous fluid, motivated by the fact that
a single constant equation of state (EOS) $p=-p_0$ ($p_0>0$) reproduces the
$\Lambda$CDM model exactly. This EOS describes the perfect fluid term, the
dissipative effect, and the cosmological constant in a unique framework and the
Friedmann equations can be analytically solved. Especially, we find a relation
between the EOS parameter and the renormalizable condition of a scalar field.
We develop a completely numerical method to perform a $\chi^2$ minimization to
constrain the parameters in a cosmological model directly from the Friedmann
equations, and employ the SNe data with the parameter $\mathcal{A}$ measured
from the SDSS data to constrain our model. The result indicates that the
dissipative effect is rather small in the late-time Universe.


title:
The new sample of giant radio sources III. Statistical trends and
  correlations

abstract:
  In this paper we analyse whether `giant' radio galaxies (GRGs) differ from
`normal'-size galaxies (NSGs) except for the linear extent of their radio
structure. We compare a number of properties of GRGs with the corresponding
properties of NSGs, and analyse the statistical trends and correlations of
physical parameters, homogeneously determined for the sources, with their
`fundamental' parameters. Using the Pearson partial-correlation test on the
correlation between two variables in the presence of one or two other
variables, we examine which correlation is the strongest. The analysis clearly
shows that GRGs do not form a separate class of radio sources. They most likely
evolve with time from smaller sources, however under specific circumstances.
Analysing properties of GRGs and NSGs together, we find that (i) the core
prominence does not correlate with the total radio luminosity (as does the core
power), but it anti-correlates with the surface brightness of the lobes of
sources, (ii) the energy density (and possibly the internal pressure) in the
lobes is independent of redshift for constant radio luminosity and size of the
sources, (iii) the equipartition magnetic-field strength, transformed into
constant source luminosity and redshift, strongly correlates with the source
size. We argue that this B_{eq} - D correlation reflects a more fundamental
correlation between B_{eq} and the source age, (iv) both the rotation and
depolarisation measures suggest Faraday screens local to the lobes of sources,
however their geometry and the composition of intervening material cannot be
determined from the global polarisation characteristics.


title: Gravitational instability via the Schrodinger equation

abstract:
  We explore a novel approach to the study of large-scale structure formation
in which self-gravitating cold dark matter (CDM) is represented by a complex
scalar field whose dynamics are governed by coupled Schrodinger and Poisson
equations. We show that, in the quasi-linear regime, the Schrodinger equation
can be reduced to the free-particle Schrodinger equation. We advocate using the
free-particle Schrodinger equation as the basis of a new approximation method -
the free-particle approximation - that is similar in spirit to the successful
adhesion model. In this paper we test the free-particle approximation by
appealing to a planar collapse scenario and find that our results are in
excellent agreement with those of the Zeldovich approximation, provided care is
taken when choosing a value for the effective Planck constant in the theory. We
also discuss how extensions of the free-particle approximation are likely to
require the inclusion of a time-dependent potential in the Schrodinger
equation. Since the Schrodinger equation with a time-dependent potential is
typically impossible to solve exactly, we investigate whether standard
quantum-mechanical approximation techniques can be used, in a cosmological
setting, to obtain useful solutions of the Schrodinger equation. In this paper
we focus on one particular approximation method: time-dependent perturbation
theory (TDPT). We elucidate the properties of perturbative solutions of the
Schrodinger equation by considering a simple example: the gravitational
evolution of a plane-symmetric density fluctuation. We use TDPT to calculate an
approximate solution of the relevant Schrodinger equation and show that this
perturbative solution can be used to successfully follow gravitational collapse
beyond the linear regime, but there are several pitfalls to be avoided.


title: Wave-mechanics and the adhesion approximation

abstract:
  The dynamical equations describing the evolution of a self-gravitating fluid
of cold dark matter (CDM) can be written in the form of a Schrodinger equation
coupled to a Poisson equation describing Newtonian gravity. It has recently
been shown that, in the quasi-linear regime, the Schrodinger equation can be
reduced to the exactly solvable free-particle Schrodinger equation. The
free-particle Schrodinger equation forms the basis of a new approximation
scheme -the free-particle approximation - that is capable of evolving
cosmological density perturbations into the quasi-linear regime. The
free-particle approximation is essentially an alternative to the adhesion model
in which the artificial viscosity term in Burgers' equation is replaced by a
non-linear term known as the quantum pressure. Simple one-dimensional tests of
the free-particle method have yielded encouraging results. In this paper we
comprehensively test the free-particle approximation in a more cosmologically
relevant scenario by appealing to an N-body simulation. We compare our results
with those obtained from two established methods: the linearized fluid approach
and the Zeldovich approximation. We find that the free-particle approximation
comprehensively out-performs both of these approximation schemes in all tests
carried out and thus provides another useful analytical tool for studying
structure formation on cosmological scales.


title:
The Positions, Colors, and Photometric Variability of Pluto's Small
  Satellites from HST Observations 2005-2006

abstract:
  Pluto's two small satellites, temporarily designated S/2005 P 1 and S/2005 P
2, were observed on four dates (15.1 and 18.1 May 2005, 15.7 February 2006, and
2.8 March 2006) using the Hubble Space Telescope's (HST) Advanced Camera for
Surveys (ACS). Here we collect together the astrometric positions of these two
satellites (henceforth P1 and P2), as well as a single color measurement for
each satellite and initial constraints on their photometric variability
obtained during these observations. We find that both satellites have
essentially neutral (grey) reflectivities, like Charon. We also find that
neither satellite exhibited strong photometric variation, which might suggest
that P1 and P2 are toward the large end of their allowable size range, and
therefore may have far lower reflectivities than Charon.


title:
Imaging and Spectroscopy of Arp 104: A Post-starburst Interacting Pair
  with Cross-Fuelling?

abstract:
  We perform UBR imaging and optical spectroscopy of the interacting galaxy
pair Arp 104, at z=0.0098. This consists of NGC5218, a disturbed Sb barred
spiral with an inclined outer shell, the round spheroidal NGC5216, a connecting
bridge of length 50 kpc and a curved plume. Neither galaxy shows emission
lines. NGC5218 has strong Balmer lines and appears to have undergone a major
starburst some 0.2 Gyr ago, triggered by the last close passage of the two
galaxies. The galaxy is very red in its centre, suggesting it is dusty, but its
outer regions, and the bridge connecting the two galaxies, have the blue
colours of 0.2-0.4 Gyr old stars. NGC5216 lacks strong Balmer lines but outside
its centre is blue in U-B, suggesting it experienced a star-formation episode
only about 40 Myr ago. This could have been fuelled by gas from
  NGC5218, transfered through the bridge. The bridge passes through NGC5216 to
emerge as a plume extending 14 kpc to the SW. The plume, from its colours, is
very young and may be a site of ongoing star-formation or the formation of a
tidal dwarf galaxy.


title:
The GRB early optical flashes from internal shocks: application to
  GRB990123, GRB041219a and GRB060111b

abstract:
  With the successful launch of the Swift Gamma-Ray Burst Explorer, people
expected the prompt optical flash like GRB990123 would be easily detected.
However the fact that early optical flash have not been detected for a number
of GRBs indicates the reverse shock must be suppressed. Here we explore the
possibility that the optical flash may arise from the internal shock. We find
that, under certain circumstance, the optical flash of GRB990123 and GRB060111b
can really be explained by the internal shock. For GRB041219a, the prompt
optical emission was correlated with the gamma-ray emission, we explain this
feature also in the internal shock scenario, the optical emission is the low
energy extension of the gamma-ray emission, and we can restrict its redshift
$z\sim 0.2$. As for GRB050904, we have shown in previous paper that the optical
flash was produced by synchrotron radiation and the X-ray flare was produced by
the synchrotron-self-Compton mechanism. Therefore we conclude that the early
optical flash of GRBs can usually come from the internal shock. Meanwhile since
the condition to produce the optical flash is not easily satisfied, so the
optical flash like GRB990123 should not be common in GRBs. In addition, we also
discussed the synchrotron-self-Compton effect in the internal shock model, and
find that for different values of parameters, there would be soft gamma-ray
(100 KeV), hard gamma-ray (10 MeV) and GeV flare accompanying the optical
flash. For GRB like GRB990123, a GeV flare with fluence about 10^{-8} erg
cm^{-2} s^{-1} is expected, which may be detected by the GLAST satellite.


title:
NGC 7419: A young open cluster with a number of very young intermediate
  mass pre-MS stars

abstract:
  We present a photometric and spectroscopic study of the young open cluster
NGC 7419, which is know to host a large number of classical Be stars for
reasons not well understood. Based on CCD photometric observations of 327 stars
in UBV passbands, we estimated the cluster parameters as, reddening E(B-V) =
1.65 +/- 0.15 mag and distance = 2900 +/- 400 pc. The turn off age of the
cluster was estimated as 25 +/- 5 Myr using isochrone fits. UBV data of the
stars were combined with JHK data from 2MASS and were used to create the near
infrared (NIR) (J-H) vs (H-K) colour-colour diagram. A large fraction of stars
(42%) was found to have NIR excess and their location in the diagram was used
to identify them as intermediate mass pre-MS stars. The isochrone fits to
pre-MS stars in the optical colour-magnitude diagram showed that the turn-on
age of the cluster is 0.3 - 3 Myr. This indicates that there has been a recent
episode of star formation in the vicinity of the cluster. Slit-less spectra
were used to identify 27 stars which showed H-alpha in emission in the field of
the cluster, of which 6 are new identifications. All these stars were found to
show NIR excess and located closer to the region populated by Herbig Ae/Be
stars in the (J-H) vs (H-K) diagram. Slit spectra of 25 stars were obtained in
the region 3700A - 9000A. The spectral features were found to be very similar
to those of Herbig Be stars. Those stars were found to be more reddened than
the main sequence stars by 0.4 mag on an average. Thus the emission line stars
found in this cluster are more similar to the Herbig Be type stars where the
circumstellar material is the remnant of the accretion disk.


title:
CMB power spectrum contribution from cosmic strings using
  field-evolution simulations of the Abelian Higgs model

abstract:
  We present the first field-theoretic calculations of the contribution made by
cosmic strings to the temperature power spectrum of the cosmic microwave
background (CMB). Unlike previous work, in which strings were modeled as
idealized one-dimensional objects, we evolve the simplest example of an
underlying field theory containing local U(1) strings, the Abelian Higgs model.
Limitations imposed by finite computational volumes are overcome using the
scaling property of string networks and a further extrapolation related to the
lessening of the string width in comoving coordinates. The strings and their
decay products, which are automatically included in the field theory approach,
source metric perturbations via their energy-momentum tensor, the unequal-time
correlation functions of which are used as input into the CMB calculation
phase. These calculations involve the use of a modified version of CMBEASY,
with results provided over the full range of relevant scales. We find that the
string tension $\mu$ required to normalize to the WMAP 3-year data at multipole
$\ell = 10$ is $G\mu = [2.04\pm0.06\textrm{(stat.)}\pm0.12\textrm{(sys.)}]
\times 10^{-6}$, where we have quoted statistical and systematic errors
separately, and $G$ is Newton's constant. This is a factor 2-3 higher than
values in current circulation.


title:
The Wide Field Imager Lyman-Alpha Search (WFILAS) for Galaxies at
  Redshift ~5.7: II. Survey Design and Sample Analysis

abstract:
  Context: Wide-field narrowband surveys are an efficient way of searching
large volumes of high-redshift space for distant galaxies.
  Aims: We describe the Wide Field Imager Lyman-Alpha Search (WFILAS) over 0.74
sq. degree for bright emission-line galaxies at z~5.7.
  Methods: WFILAS uses deep images taken with the Wide Field Imager (WFI) on
the ESO/MPI 2.2m telescope in three narrowband (70 A), one encompassing
intermediate band (220 A) and two broadband filters, B and R. We use the novel
technique of an encompassing intermediate band filter to exclude false
detections. Images taken with broadband B and R filters are used to remove low
redshift galaxies from our sample.
  Results: We present a sample of seven Lya emitting galaxy candidates, two of
which are spectroscopically confirmed. Compared to other surveys all our
candidates are bright, the results of this survey complements other narrowband
surveys at this redshift. Most of our candidates are in the regime of bright
luminosities, beyond the reach of less voluminous surveys. Adding our
candidates to those of another survey increases the derived luminosity density
by ~30%. We also find potential clustering in the Chandra Deep Field South,
supporting overdensities discovered by other surveys. Based on a FORS2/VLT
spectrum we additionally present the analysis of the second confirmed Lya
emitting galaxy in our sample. We find that it is the brightest Lya emitting
galaxy (1 x 10^-16 erg s^-1 cm^-2) at this redshift to date and the second
confirmed candidate of our survey. Both objects exhibit the presence of a
possible second Lya component redward of the line.


title: Anisotropy of the primary cosmic-ray flux in Super-Kamiokande

abstract:
  A first-ever 2-dimensional celestial map of primary cosmic-ray flux was
obtained from 2.10x10^8 cosmic-ray muons accumulated in 1662.0 days of
Super-Kamiokande. The celestial map indicates an (0.104 \pm 0.020)% excess
region in the constellation of Taurus and a -(0.094 \pm 0.014)% deficit region
toward Virgo. Interpretations of this anisotropy are discussed.


title: Wronskian Formulation of the Spectrum of Curvature Perturbations

abstract:
  We present a new formulation for the evaluation of the primordial spectrum of
curvature perturbations generated during inflation, using the fact that the
Wronskian of the scalar field perturbation equation is constant. In the
literature, there are many works on the same issue focusing on a few specific
aspects or effects. Here we deal with the general multi-component scalar field,
and show that our new formalism gives a method to evaluate the final amplitude
of the curvature perturbation systematically and economically. The advantage of
the new method is that one only has to solve a single mode of the scalar field
perturbation equation backward in time from the end of inflation to the stage
at which the perturbation is within the Hubble horizon, at which the initial
values of the scalar field perturbations are given. We also clarify the
relation of the new method with the new delta N formalism recently developed in
Lee et al.(2005).


title: The radii of thousands of star clusters in M51 with HST/ACS

abstract:
  We exploit the superb resolution of the new HST/ACS mosaic image of M51 to
select a large sample of young (< 1 Gyr) star clusters in the spiral disk,
based on their sizes. The image covers the entire spiral disk in B, V, I and
H_alpha, at a resolution of 2 pc per pixel. The surface density distribution of
4357 resolved clusters shows that the clusters are more correlated with clouds
than with stars, and we find a hint of enhanced cluster formation at the
corotation radius. The radius distribution of a sample of 769 clusters with
more accurate radii suggests that young star clusters have a preferred
effective radius of ~3 pc, which is similar to the preferred radius of the much
older GCs. However, in contrast to the GCs, the young clusters in M51 do not
show a relation between radius and galactocentric distance. This means that the
clusters did not form in tidal equilibrium with their host galaxy, nor that
their radius is related to the ambient pressure.


title: The effect of giant molecular clouds on star clusters

abstract:
  We study the encounters between stars clusters and giant molecular clouds
(GMCs). The effect of these encounters has previously been studied analytically
for two cases: 1) head-on encounters, for which the cluster moves through the
centre of the GMC and 2) distant encounters, where the encounter distance p >
3*R_n, with p the encounter parameter and R_n the radius of the GMC. We
introduce an expression for the energy gain of the cluster due to GMC
encounters valid for all values of p and R_n. This analytical result is
confronted with results from N-body simulations and excellent agreement is
found. From the simulations we find that the fractional mass loss is only 25%
of the fractional energy gain. This is because stars escape with velocities
much higher than the escape velocity. Based on the mass loss, we derive a
disruption time for star clusters due to encounters with GMCs of the form t_dis
[Gyr] = 2.0*S*(M_c/10^4 M_sun)^gamma, with S=1 for the solar neighbourhood and
inversely proportional with the global GMC density and gamma=1-3lambda, with
lambda the index that relates the cluster half-mass radius to the cluster mass
(r_h ~ M_c^lambda). The observed shallow relation between cluster radius and
mass (e.g. lambda=0.1), makes the index (gamma=0.7) similar to the index found
both from observations and from simulations of clusters dissolving in tidal
fields (gamma=0.62). The constant of 2.0 Gyr, which is the disruption time of a
10^4 M_sun cluster in the solar neighbourhood, is close to the value of 1.3 Gyr
which was empirically determined from the age distribution of open clusters.
This suggests that the combined effect of GMC encounters, stellar evolution and
galactic tidal field can explain the lack of old open clusters in the solar
neighbourhood.


title: Broad band X-ray spectrum of KS 1947+300 with BeppoSAX

abstract:
  We present results obtained from three BeppoSAX observations of the
accretion-powered transient X-ray pulsar KS 1947+300 carried out during the
declining phase of its 2000 November -- 2001 June outburst. A detailed spectral
study of KS 1947+300 across a wide X-ray band (0.1--100.0 keV) is attempted for
the first time here. Timing analysis of the data clearly shows a 18.7 s
pulsation in the X-ray light curves in the above energy band. The pulse profile
of KS 1947+300 is characterized by a broad peak with sharp rise followed by a
narrow dip. The dip in the pulse profile shows a very strong energy dependence.
Broad-band pulse-phase-averaged spectroscopy obtained with three of the
BeppoSAX instruments shows that the energy spectrum in the 0.1--100 keV energy
band has three components, a Comptonized component, a ~0.6 keV blackbody
component, and a narrow and weak iron emission line at 6.7 keV with a low
column density of material in the line of sight. We place an upper limit on the
equivalent width of the iron K_\alpha line at 6.4 keV of ~13 eV (for a width of
100 eV). Assuming a spherical blackbody emitting region and the distance of the
source to be 10 kpc, the radius of the emitting region is found to be in the
range of 14--22 km, which rules out the inner accretion disk as the soft X-ray
emitting region.


title: The Field of Streams: Sagittarius and its Siblings

abstract:
  We use Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) u,g,r,i,z
photometry to study Milky Way halo substructure in the area around the North
Galactic Cap. A simple color cut (g-r < 0.4) reveals the tidal stream of the
Sagittarius dwarf spheroidal, as well as a number of other stellar structures
in the field. Two branches (A and B) of the Sagittarius stream are clearly
visible in an RGB-composite image created from 3 magnitude slices, and there is
also evidence for a still more distant wrap behind the A branch. A comparison
of these data with numerical models suggests that the shape of the Galactic
dark halo is close to spherical.


title: The Origin of the Bifurcation in the Sagittarius Stream

abstract:
  The latest Sloan Digital Sky Survey data reveal a prominent bifurcation in
the distribution of debris of the Sagittarius dwarf spheroidal (Sgr) beginning
at a right ascension of roughly 190 degrees. Two branches of the stream (A and
B) persist at roughly the same heliocentric distance over at least 50 degrees
of arc. There is also evidence for a more distant structure (C) well behind the
A branch. This paper provides the first explanation for the bifurcation. It is
caused by the projection of the young leading (A) and old trailing (B) tidal
arms of the Sgr, whilst the old leading arm (C) lies well behind A. This
explanation is only possible if the halo is close to spherical, as the angular
difference between the branches is a measure of the precession of the orbital
plane.


title:
X-ray Absorption in Type II Quasars: Implications for the Equatorial
  Paradigm of Broad Absorption Line Quasars

abstract:
  In this article, the hydrogen column densities derived from X-ray
observations of type II (hidden) quasars and broad absorption line quasars
(BALQSOs) are compared. These column densities represent the amount of
absorbing material between the X-ray source and the observer. A sample of type
II QSOs with strong narrow emission lines, weak UV continuum and no broad
emission lines that also have deep X-ray observations was collected from the
literature for analysis. The standard model of equatorial BAL (broad absorption
line) winds predicts that the column densities of this type II QSO sample
should significantly exceed BALQSO column densities. Based on the existing
published deep hard X-ray observations this does not seem to be true, the
BALQSO absorption columns are anomalously large. Actually, the limited existing
data indicate that BALQSOs have column densities which are larger than the type
II QSO column densities at a statistically significant level. The implication
to BAL outflows and the fundamental physical geometry of QSOs is discussed.


title: Searching for sub-millisecond pulsars: A theoretical view

abstract:
  Sub-millisecond pulsars should be triaxial (Jacobi ellipsoids), which may not
spin down to super-millisecond periods via gravitation wave radiation during
their lifetimes if they are extremely low mass bare strange quark stars. It is
addressed that the spindown of sub-millisecond pulsars would be torqued
dominantly by gravitational wave radiation (with braking index n ~ 5). The
radio luminosity of sub-millisecond pulsars could be high enough to be detected
in advanced radio telescopes. Sub-millisecond pulsars, if detected, should be
very likely quark stars with low masses and/or small equatorial ellipticities.


title: High Resolution Irradiance Spectrum from 300 to 1000 nm

abstract:
  The FTS scans that made up the Kitt Peak Solar Flux Atlas by Kurucz,
Furenlid, Brault, and Testerman (1984) have been re-reduced. An approximate
telluric atmospheric model was determined for each FTS scan. Large-scale
features produced by O3 and O2 dimer were computed and divided out. The solar
continuum level was found by fitting a smooth curve to high points in each
scan. The scans were normalized to the fitted continuum to produce a residual
flux spectrum for each FTS scan. The telluric line spectrum was computed using
HITRAN and other line data for H2O, O2, and CO2. The line parameters were
adjusted for an approximate match to the observed spectra. The scans were
divided by the computed telluric spectra to produce residual irradiance
spectra. Artifacts from wavelength mismatches, deep lines, etc, were removed by
hand and replaced by linear interpolation. Overlapping scans were fitted
together to make a continuous spectrum from 300 to 1000 nm. All the above steps
were iterative. The monochromatic error varies from 0.1 to 1.0 percent. The
residual spectrum was calibrated two different ways: First by normalizing it to
the continuum of theoretical solar model ASUN (Kurucz 1992), and second, by
degrading the spectrum to the resolution of the observed irradiance (Thuillier
et al. 2004) to determine a normalization function that was then applied to the
high resolution spectrum.


title:
The Discovery of Three New z>5 Quasars in the AGN and Galaxy Evolution
  Survey

abstract:
  We present the discovery of three z>5 quasars in the AGN and Galaxy Evolution
Survey (AGES) spectroscopic observations of the NOAO Deep Wide-Field Survey
(NDWFS) Bootes Field. These quasars were selected as part of a larger Spitzer
mid-infrared quasar sample with no selection based on optical colors. The
highest redshift object, NDWFS J142516.3+325409, z=5.85, is the
lowest-luminosity z>5.8 quasar currently known. We compare mid-infrared
techniques for identifying z>5 quasars to more traditional optical techniques
and show that mid-infrared colors allow for selection of high-redshift quasars
even at redshifts where quasars lie near the optical stellar locus and at z>7
where optical selection is impossible. Using the superb multi-wavelength
coverage available in the NDWFS Bootes field, we construct the spectral energy
distributions (SEDs) of high-redshift quasars from observed Bw-band to 24
microns (rest-frame 600 Angstroms - 3.7 microns). We show that the three
high-redshift quasars have quite similar SEDs, and the rest-frame composite SED
of low-redshift quasars from the literature shows little evolution compared to
our high-redshift objects. We compare the number of z>5 quasars we have
discovered to the expected number from published quasar luminosity functions.
While analyses of the quasar luminosity function are tenuous based on only
three objects, we find that a relatively steep luminosity function with Psi
L^(-3.2) provides the best agreement with the number of high-redshift quasars
discovered in our survey.