title: Clues to Nuclear Star Cluster Formation from Edge-on Spirals

abstract:
  We find 9 nuclear cluster candidates in a sample of 14 edge-on, late-type
galaxies observed with HST/ACS. These clusters have magnitudes (M_I ~ -11) and
sizes (r_eff ~ 3pc) similar to those found in previous studies of face-on,
late-type spirals and dE galaxies. However, three of the nuclear clusters are
significantly flattened and show evidence for multiple, coincident structural
components. The elongations of these three clusters are aligned to within 10
degrees of the galaxies' major axes. Structurally, the flattened clusters are
well fit by a combination of a spheroid and a disk or ring. The nuclear cluster
disks/rings have F606W-F814W (~V-I) colors 0.3-0.6 magnitudes bluer than the
spheroid components, suggesting that the stars in these components have ages <
1 Gyr. In NGC 4244, the nearest of the nuclear clusters, we further constrain
the stellar populations and provide a lower limit on the dynamical mass via
spectroscopy. We also present tentative evidence that another of the nuclear
clusters (in NGC 4206) may also host a supermassive black hole. Based on our
observational results we propose an in situ formation mechanism for nuclear
clusters in which stars form episodically in compact nuclear disks, and then
lose angular momentum or heat vertically to form an older spheroidal structure.
We estimate the period between star formation episodes to be 0.5 Gyr and
discuss possible mechanisms for tranforming the disk-like components into
spheroids. We also note the connection between our objects and massive globular
clusters (e.g. $\omega$ Cen), UCDs, and SMBHs. (Abridged)


title: Virial Masses of Black Holes from Single Epoch Spectra of AGN

abstract:
  We describe the general problem of estimating black hole masses of AGN by
calculating the conditional probability distribution of M_BH given some set of
observables. Special attention is given to the case where one uses the AGN
continuum luminosity and emission line widths to estimate M_BH, and we outline
how to set up the conditional probability distribution of M_BH given the
observed luminosity, line width, and redshift. We show how to combine the broad
line estimates of M_BH with information from an intrinsic correlation between
M_BH and L, and from the intrinsic distribution of M_BH, in a manner that
improves the estimates of M_BH. Simulation was used to assess how the
distribution of M_BH inferred from the broad line mass estimates differs from
the intrinsic distribution, and we find that this can lead to an inferred
distribution that is too broad. We use these results and a sample of 25 sources
that have recent reverberation mapping estimates of AGN black hole masses to
investigate the effectiveness of using the C IV emission line to estimate M_BH
and to indirectly probe the C IV region size--luminosity (R--L) relationship.
We estimated M_BH from both C IV and H-Beta for a sample of 100 sources,
including new spectra of 29 quasars. We find that the two emission lines give
consistent estimates if one assumes R \propto L^{1/2}_{UV} for both lines.


title:
An X-ray Census of Young Stars in the Massive Southern Star-Forming
  Complex NGC 6357

abstract:
  We present the first high spatial resolution X-ray study of the massive star
forming region NGC 6357, obtained in a 38 ks Chandra/ACIS observation. Inside
the brightest constituent of this large HII region complex is the massive open
cluster Pismis 24. It contains two of the brightest and bluest stars known, yet
remains poorly studied; only a handful of optically bright stellar members have
been identified. We investigate the cluster extent and Initial Mass Function
and detect ~800 X-ray sources with a limiting sensitivity of 10^{30} ergs
s^{-1}; this provides the first reliable probe of the rich intermediate-mass
and low-mass population of this massive cluster, increasing the number of known
members from optical study by a factor of ~50. The high luminosity end (log
L_h[2-8 keV]\ge 30.3 ergs s^{-1}) of the observed X-ray luminosity function in
NGC 6357 is clearly consistent with a power law relation as seen in the Orion
Nebula Cluster and Cepheus B, yielding the first estimate of NGC 6357's total
cluster population, a few times the known Orion population. We investigate the
structure of the cluster, finding small-scale substructures superposed on a
spherical cluster with 6 pc extent, and discuss its relationship to the nebular
morphology. The long-standing Lx - 10^{-7}L_{bol} correlation for O stars is
confirmed. Twenty-four candidate O stars and one possible new obscured massive
YSO or Wolf-Rayet star are presented. Many cluster members are estimated to be
intermediate-mass stars from available infrared photometry (assuming an age of
1 Myr), but only a few exhibit K-band excess. We report the first detection of
X-ray emission from an Evaporating Gaseous Globule at the tip of a molecular
pillar; this source is likely a B0-B2 protostar.


title:
A Statistical Stability Analysis of Earth-like Planetary Orbits in
  Binary Systems

abstract:
  This paper explores the stability of an Earth-like planet orbiting a
solar-mass star in the presence of a stellar companion using ~ 400,000
numerical integrations. Given the chaotic nature of the systems being
considered, we perform a statistical analysis of the ensuing dynamics for ~500
orbital configurations defined by the following set of orbital parameters: the
companion mass; the companion eccentricity; the companion periastron; and the
planet's inclination angle relative to the stellar binary plane. Specifically,
we generate a large sample of survival times for each orbital configuration
through the numerical integration of N >> 1 equivalent experiments (e.g., with
the same orbital parameters but randomly selected initial orbital phases). We
then construct distributions of survival time using the variable mu_s = log
tau_s (where tau_s is in years) for each orbital configuration. The primary
objective of this work is twofold. First, we use the mean of the distributions
to gain a better understanding of what orbital configurations, while unstable,
have sufficiently long survival times to make them interesting to the study of
planet habitability. Second, we calculate the width, skew, and kurtosis of each
mu_s distribution and look for general features that may aid further
understanding and numerical exploration of these chaotic systems.


title:
Contribution of unresolved point sources to the galactic diffuse
  emission

abstract:
  The detection by the HESS atmospheric Cherenkov telescope of fifteen new
sources from the Galactic plane makes it possible to estimate the contribution
of unresolved point sources like those detected by HESS to the diffuse Galactic
emission measured by EGRET and recently at higher energies by the Milagro
Collaboration. Assuming that HESS sources have all the same intrinsic
luminosity, the contribution of this new source population can account for most
of the Milagro $\gamma$-ray emission at TeV energies and between 10 and 20 per
cent of EGRET diffuse Galactic $\gamma$-ray emission for energies bigger than
10 GeV. Also, by combining the HESS and the Milagro results, constraints can be
put on the distribution and the luminosities of gamma ray emitters in the
Galaxy.


title: Temporal variability of the telluric sodium layer

abstract:
  The temporal variability of the telluric sodium layer is investigated by
analyzing 28 nights of data obtained with the Colorado State University LIDAR
experiment. The mean height power spectrum of the sodium layer was found to be
well fit by a power law over the observed range of frequencies, 10 microhertz
to 4 millhertz. The best fitting power law was found to be 10^\beta \nu^\alpha,
with \alpha = -1.79 +/- 0.02 and \beta = 1.12 +/- 0.40. Applications to
wavefront sensing require knowledge of the behavior of the sodium layer at kHz
frequencies. Direct measurements at these frequencies do not exist.
Extrapolation from low-frequency behavior to high frequencies suggests that
this variability may be a significant source of error for laser-guide-star
adaptive optics on large-aperture telescopes.


title:
Evidence for Solar-Wind Charge-Exchange X-Ray Emission from the Earth's
  Magnetosheath

abstract:
  We report an apparent detection of the C VI 4p to 1s transition line at 459
eV, during a long-term enhancement (LTE) in the Suzaku north ecliptic pole
(NEP) observation of 2005 September 2. The observed intensity of the line is
comparable to that of the C VI 2p to 1s line at 367 eV. This is strong evidence
for the charge-exchange process. In addition to the C VI lines, emission lines
from O VII, O VIII, Ne X, and Mg XI lines showed clear enhancements. There are
also features in the 750 to 900 eV range that could be due to some combination
of Fe XVII and XVIII L-lines, higher order transitions of O VIII (3p to 1s and
6p to 1s), and a Ne IX line. From the correlation of the X-ray intensity with
solar-wind flux on time scales of about half a day, and from the short-term
(~10 minutes) variations of the X-ray intensity, these lines most likely arise
from solar-wind heavy ions interacting with neutral material in the Earth's
magnetosheath. A hard power-law component is also necessary to explain the LTE
spectrum. The origin of this component is not yet known. Our results indicate
that solar activity can significantly contaminate Suzaku cosmic X-ray spectra
below ~1 keV. Recommendations are provided for recognizing such contamination
in observations of extended sources.


title:
A Shell of Thermal X-ray Emission Associated with the Young Crab-like
  Remnant 3C58

abstract:
  Deep X-ray imaging spectroscopy of the bright pulsar wind nebula 3C58
confirms the existence of an embedded thermal X-ray shell surrounding the
pulsar PSR J0205+6449. Radially resolved spectra obtained with the XMM-Newton
telescope are well-characterized by a power-law model with the addition of a
soft thermal emission component in varying proportions. These fits reproduce
the well-studied increase in the spectral index with radius attributed to
synchrotron burn-off of high energy electrons. Most interestingly, a radially
resolved thermal component is shown to map out a shell-like structure ~6' in
diameter. The presence of a strong emission line corresponding to the Ne IX
He-like transition requires an overabundance of ~3 x [Ne/Ne(sun)] in the
Raymond-Smith plasma model. The best-fit temperature kT ~ 0.23 keV is
essentially independent of radius for the derived column density of N_H = (4.2
+/- 0.1)E21 per cm squared. Our result suggests that thermal shells can be
obscured in the early evolution of a supernova remnant by non-thermal pulsar
wind nebulae emission; the luminosity of the 3C58 shell is more than an order
of magnitude below the upper limit on a similar shell in the Crab Nebula. We
find the shell centroid to be offset from the pulsar location. If this neutron
star has a velocity similar to that of the Crab pulsar, we derive an age of
3700 yr and a velocity vector aligned with the long axis of the PWN. The shell
parameters and pulsar offset add to the accumulating evidence that 3C58 is not
the remnant of the supernova of CE 1181.


title: Discoveries of Diffuse Iron Line Sources from the Sgr B Region

abstract:
  The radio complex Sgr B region is observed with the X-Ray Imaging
Spectrometers (XIS) on board Suzaku. This region exhibits diffuse iron lines at
6.4, 6.7 and 6.9 keV, which are K$\alpha$ lines of Fe \emissiontype{I} (neutral
iron), Fe\emissiontype{XXV} (He-like iron) and Fe\emissiontype{XXVI} (H-like
iron), respectively. The high energy resolving power of the XIS provides the
separate maps of the K-shell transition lines from Fe\emissiontype{I} (6.4 keV)
and Fe\emissiontype{XXV} (6.7 keV). Although the 6.7 keV line is smoothly
distributed over the Sgr B region, a local excess is found near at $(l, b) =
(\timeform {0D.61}, \timeform{0D.01})$, possibly a new SNR. The plasma
temperature is \textit{kT} $\sim$3 keV and the age is estimated to be around
several$\times10^{3}$ years. The 6.4 keV image is clumpy with local excesses
nearby Sgr B2 and at $(l, b) = (\timeform{0D.74}, -\timeform{0D.09})$. Like Sgr
B2, this excess may be another candidate of an X-ray reflection nebula (XRN).


title: Report by the ESA-ESO Working Group on "The Herschel-ALMA Synergies"

abstract:
  The Herschel Satellite and the Atacama Large Millimeter Array (ALMA) are two
very large sub-mm and far infrared (FIR) astronomy projects that are expected
to come into operation in this decade. This report contains descriptions of
these instruments, emphasising the overlaps in wavelength range and additional
complementarities.
  A short rationale for studying sub-mm and far infrared astronomy is given.
Following this, brief presentations of Herschel and ALMA are presented, with
references to more detailed documents and use cases. Emphasis is placed on the
synergies between these facilities, and the challenges of comparing data
produced using both. Specific examples of projects are given for a number of
areas of astronomical research where these facilities will lead to dramatic
improvements.
  This report is addressed to an audience of non-specialist astronomers who may
be interested in extending their areas of research by making use of Herschel
and ALMA instruments.


title:
Chemical stratification in the atmosphere of Ap star HD 133792.
  Regularized solution of the vertical inversion problem

abstract:
  High spectral resolution studies of cool Ap stars reveal conspicuous
anomalies of the shape and strength of many absorption lines. This is a
signature of large atmospheric chemical gradients produced by the selective
radiative levitation and gravitational settling of chemical species. Here we
present a new approach to mapping the vertical chemical structures in stellar
atmospheres. We have developed a regularized chemical inversion procedure that
uses all information available in high-resolution stellar spectra. The new
technique for the first time allowed us to recover chemical profiles without
making a priori assumptions about the shape of chemical distributions. We have
derived average abundances and applied the vertical inversion procedure to the
high-resolution VLT UVES spectra of the weakly magnetic, cool Ap star HD
133792. Our analysis yielded improved estimates of the atmospheric parameters
of HD 133792. We show that this star has negligible vsini and the mean magnetic
field modulus <B>=1.1+/-0.1 kG. We have derived average abundances for 43 ions
and obtained vertical distributions of Ca, Si, Mg, Fe, Cr, and Sr. All these
elements except Mg show high overabundance in the deep layers and solar or
sub-solar composition in the upper atmosphere of HD 133792. In contrast, the Mg
abundance increases with height. We find that transition from the
metal-enhanced to metal-depleted zones typically occurs in a rather narrow
range of depths in the atmosphere of HD 133792. Based on the derived
photospheric abundances, we conclude that HD 133792 belongs to the rare group
of evolved cool Ap stars, which possesses very large Fe-peak enhancement, but
lacks a prominent overabundance of the rare-earth elements.


title: Energy Conservation at the Gravitational Collapse

abstract:
  We apply the principle of energy conservation to the motion of the test
particle in gravitational field by requiring that its energy, gained by
gravitation, has to be balanced by decrease of its rest mass. Due to the change
of mass in gravitational field Newton's force law between gravitating bodies is
modified, too. With this modified force law we build up the the classical field
theory of gravitation in which all relevant field quantities are in the
definition domain $r\in [0,\infty)$ finite and positive. We show that under
such circumstances, the energy release at any gravitational collapse is finite.
On the other side, the energy conservation leads to an equation which relates
the mass change of the test particle due to gravitation and the metric of the
corresponding gravitational field. The mass change in Newton's gravitational
field lead to a remarkable simple metric which shifts, in contrast to the
Schwarzschild metric, the horizon of events to the gravity center of the
gravitational collapse.


title:
Revisiting the Baryon Fractions of Galaxy Clusters: A Comparison with
  WMAP 3-year Results

abstract:
  The universal baryonic mass fraction (Omega_b/Omega_m) can be sensitively
constrained using X-ray observations of galaxy clusters. In this paper, we
compare the baryonic mass fraction inferred from measurements of the cosmic
microwave background with the gas mass fractions (f_gas) of a large sample of
clusters taken from the recent literature. In systems cooler than 4 keV, f_gas
declines as the system temperature decreases. However, in higher temperature
systems, f_gas(r500) converges to approx. (0.12 +/- 0.02)(h/0.72)^{-1.5}, where
the uncertainty reflects the systematic variations between clusters at r500.
This is significantly lower than the maximum-likelihood value of the baryon
fraction from the recently released WMAP 3-year results. We investigate
possible reasons for this discrepancy, including the effects of radiative
cooling and non-gravitational heating, and conclude that the most likely
solution is that Omega_m is higher than the best-fit WMAP value (we find
Omega_m = 0.36^{+0.11}_{-0.08}), but consistent at the 2-sigma level.
Degeneracies within the WMAP data require that sigma_8 must also be greater
than the maximum likelihood value for consistency between the data sets.


title:
Reinterpreting quintessential dark energy through averaged inhomogeneous
  cosmologies

abstract:
  Regionally averaged relativistic cosmologies have recently been considered as
a possible explanation for the apparent late time acceleration of the Universe.
This contribution reports on a mean field description of the backreaction in
terms of a minimally coupled regionally homogeneous scalar field evolving in a
potential, then giving a physical origin to the various phenomenological scalar
fields generically called quintessence fields. As an example, the
correspondence is then applied to scaling solutions.


title:
A Canis Major over-density imaging survey. I. Stellar content and
  star-count maps : A distinctly elongated body of main sequence stars

abstract:
  [Abridged] We present first results from a large-area (~80degx20deg),
sparsely sampled two-filter (B,R) imaging survey towards the Canis Major
stellar over-density, claimed to be a disrupting Milky Way satellite galaxy.
Utilizing stellar colour-magnitude diagrams reaching to B ~ 22 mag, we provide
a first delineation of its surface density distribution using main sequence
stars. Its projected shape is highly elongated, nearly parallel to the Galactic
plane, with an axis ratio of >~ 5:1, substantially more so than what Martin et
al. originally found. We also provide a first map of a prominent over-density
of blue, presumably younger main sequence stars, which appears to have a
maximum near [l,b = 240,-7 deg]. The young population is markedly more
localized. We estimate an upper limit on the line-of-sight (l.o.s.) depth of
the old population based on the main sequence width, obtaining sigma_los < 1.8
+/- 0.3 kpc, at an adopted D_helio = 7.5 +/- 1 kpc. For the young stellar
population, we find sigma_los < 1.5 kpc. There are different explanations for
the CMa over-density: (a) a partially disrupting dwarf galaxy on a low-latitude
orbit, (b) a projection of the warped outer Galactic disk, and (c) a projection
of an out-of-plane spiral arm. While the data provide no firm arguments against
the less well-defined third scenario, they have clear implications for each of
the others: (a) We infer from the strong elongation in longitude, and
simulations in the literature, that the over-density is unlikely to be a
gravitationally bound system at the present epoch, but may well be just a
recently disrupted satellite remnant. (b) Based on modeling, the line-of-sight
depth of the over-density in old stars is clearly inconsistent with published
locally axi-symmetric descriptions of the warped Galactic disk.


title: GRBs search results with the ARGO-YBJ experiment operated in Scaler Mode

abstract:
  The ARGO-YBJ experiment is almost completely installed at the YangBaJing
Cosmic Ray Laboratory (4300 m a.s.l., Tibet, P.R. China). The lower energy
limit of the detector (E $\sim$ 1 GeV) is reached with the scaler mode, i.e.,
recording the single particle rate at fixed time intervals. In this technique,
due to its high altitude location and large area ($\sim$ 6700 m$^2$), this
experiment is the most sensitive among all present and past ground-based
detectors. In the energy range under investigation, signals due to local (e.g.
solar GLEs) and cosmological (e.g. GRBs) phenomena are expected as significant
enhancements of the counting rate over the background. Results on the search
for GRBs in coincidence with satellite detections are presented.


title: C- and O-Rich Miras and Galactic Structure

abstract:
  This paper summarizes the conclusions of an extensive investigation of
variable carbon AGB stars in our Galaxy. The zero-point of the period-M(bol)
relation for Galactic C-Miras is found to be close to that in the LMC. The mean
age of Galactic C-Miras is about 1.8 Gyr and their initial masses about 1.8
solar masses with some evidence that age decreases and initial mass increases
with increasing pulsation period. Kinematic studies of Galactic C- and O-Miras
show that the relative frequency of these two Mira classes depends on the age
of the parent population. The lack of carbon stars in the Galactic Bulge seems
due to a high oxygen abundance. The velocity dispersion of O-Miras allows one
to distinguish between two possible models of Galactic kinematics.


title:
Long term spectral variability in the Soft Gamma-ray Repeater SGR
  1900+14

abstract:
  We present a systematic analysis of all the BeppoSAX data of SGR1900+14. The
observations spanning five years show that the source was brighter than usual
on two occasions: ~20 days after the August 1998 giant flare and during the
10^5 s long X-ray afterglow following the April 2001 intermediate flare. In the
latter case, we explore the possibility of describing the observed short term
spectral evolution only with a change of the temperature of the blackbody
component. In the only BeppoSAX observation performed before the giant flare,
the spectrum of the SGR1900+14 persistent emission was significantly harder and
detected also above 10 keV with the PDS instrument. In the last BeppoSAX
observation (April 2002) the flux was at least a factor 1.2 below the
historical level, suggesting that the source was entering a quiescent period.


title: Optical Physics of Imaging and Interferometric Phased Arrays

abstract:
  Microwave, submillimetre-wave, and far-infrared phased arrays are of
considerable importance for astronomy. We consider the behaviour imaging phased
arrays and interferometric phased arrays from a functional perspective. It is
shown that the average powers, field correlations, power fluctuations, and
correlations between power fluctuations at the output ports of an imaging or
interferometric phased array can be found once the synthesised reception
patterns are known. The reception patterns do not have to be orthogonal or even
linearly independent. It is shown that the operation of phased arrays is
intimately related to the mathematical theory of frames, and that the theory of
frames can be used to determine the degree to which any class of intensity or
field distribution can be reconstructed unambiguously from the complex
amplitudes of the travelling waves at the output ports. The theory can be used
to set up a likelihood function that can, through Fisher information, be used
to determine the degree to which a phased array can be used to recover the
parameters of a parameterised source. For example, it would be possible to
explore the way in which a system, perhaps interferometric, might observe two
widely separated regions of the sky simultaneously.


title: ASTRA Spectrophotometer: Reduction and Flux Calibrations

abstract:
  The ASTRA Cassegrain Spectrophotometer and its automated 0.5-m telescope at
Fairborn Observatory in Arizona will produce a large quantity of high precision
stellar flux distributions. A separate paper (Adelman et al. 2007) presented a
review of the design criteria for the system and an overview of its operation.
This paper discusses the techniques used in the data reduction to final flux
calibrations.


title:
Gemini Near Infrared Integral Field Spectroscopy of the Narrow-Line
  Region of ESO428-G14: kinematics, excitation and the role of the radio jet

abstract:
  We present 2D gas kinematics and excitation of the inner 300 pc of the
Seyfert galaxy ESO428-G14 at a sampling of 14 pc^2, from near-IR spectroscopic
observations at R~6000 obtained with the IFU of the Gemini Near-Infrared
Spectrograph. From measurements of fluxes and profiles of the emission lines
[FeII]lambda1.257, Pa_beta, H_2lambda2.121 and Br_gamma, we construct 2D maps
of line intensities and ratios, radial velocities and velocity dispersions.
Emission lines "tomography" is provided by velocity slices obtained across the
line profiles, which allows the mapping of not only of peak velocities but
including also the wings. We compare these maps with a previously published
high spatial resolution radio map and find a tight relation between the radio
structure and the emission-line flux distributions and kinematics, revealing
that the radio-jet plays a fundamental role not only in shaping the NLR but
also in the imprint of its kinematics. Blueshifts of up to 400 km/s and
velocity dispersions of up to 150 km/s are observed in association with the
radio jet at position angle PA=129, which is also the PA of the photometric
major axis of the galaxy. The [FeII] shows the largest blueshifts and velocity
dispersions and its flux distribution is concentrated along the jet, while the
H_2 shows the lowest velocity dispersions and has additional flux contribution
from regions beyond the jet. We use the 2D velocity dispersion maps to estimate
upper limits to the contribution of the radio jet to the excitation of [FeII]
and H_2 which may reach 90% for [FeII] and 80% for H_2 in the jet region. The
[FeII]/Pa_beta emission-line ratios and the association of the [FeII] flux
distribution and kinematics with the radio structure supports a stronger
contribution of the radio jet to the [FeII] excitation than to that of H_2.


title: Evidence for a High Carbon Abundance in the Local Interstellar Cloud

abstract:
  The nature of the Local Interstellar Cloud (LIC) is highly constrained by the
combination of in situ heliospheric and line-of-sight data towards nearby
stars. We present a new interpretation of the LIC components of the absorption
line data towards epsilon CMa, based on recent atomic data that include new
rates for the Mg+ to Mg0 dielectronic recombination rate, and using in situ
measurements of the temperature and density of neutral helium inside of the
heliosphere. With these data we are able to place interesting limits on the gas
phase abundance of carbon in the LIC. If the C/S abundance ratio is solar, ~20,
then no simultaneous solution exists for the N(Mg I), N(Mg II), N(C II) and N(C
II*) data. The combined column density and in situ data favor an abundance
ratio A(C)/A(S) = 47 +22 -26.
  We find that the most probable gas phase C abundance is in the range 400 to
800 ppm with a lower limit of ~330. We speculate that such a supersolar
abundance could have come to be present in the LIC via destruction of decoupled
dust grains. Similar enhanced C/H ratios are seen in very low column density
material, N(H) < 10^19 cm^-2, towards several nearby stars.


title: Stellar Fluxes as Probes of Convection in Stellar Atmospheres

abstract:
  Convection and turbulence in stellar atmospheres have a significant effect on
the emergent flux from late-type stars. The theoretical advancements in
convection modelling over recent years have proved challenging for the
observers to obtain measurements with sufficient precision and accuracy to
allow discrimination between the various predictions.
  An overview of the current observational techniques used to evaluate various
convection theories is presented, including photometry, spectrophotometry, and
spectroscopy. The results from these techniques are discussed, along with their
successes and limitations.
  The prospects for improved observations of stellar fluxes are also given.


title: Light Curves for Rapidly-Rotating Neutron Stars

abstract:
  We present raytracing computations for light emitted from the surface of a
rapidly-rotating neutron star in order to construct light curves for X-ray
pulsars and bursters. These calculations are for realistic models of
rapidly-rotating neutron stars which take into account both the correct
exterior metric and the oblate shape of the star. We find that the most
important effect arising from rotation comes from the oblate shape of the
rotating star. We find that approximating a rotating neutron star as a sphere
introduces serious errors in fitted values of the star's radius and mass if the
rotation rate is very large. However, in most cases acceptable fits to the
ratio M/R can be obtained with the spherical approximation.


title:
Baryonic Collapse within Dark Matter Halos and the Formation of Gaseous
  Galactic Disks

abstract:
  This paper constructs an analytic framework for calculating the assembly of
galactic disks from the collapse of gas within dark matter halos, with the goal
of determining the surface density profiles. Gas parcels (baryons) fall through
the potentials of dark matter halos on nearly ballistic, zero energy orbits and
collect in a rotating disk. The dark matter halos have a nearly universal form,
as determined previously through numerical simulations. The calculation is
first carried out for a variety of pre-collapse mass distributions and rotation
profiles, including polytropic spheres in hydrostatic equilibrium with the halo
potential. The resulting disk surface density profiles have nearly power-law
forms, with well-defined edges. This idealized scenario is generalized to
include non-spherical starting states and multiple accretion events (due to gas
being added to the halo via merger events). This latter complication is
explored in detail and considers a log-normal distribution for the angular
momenta of the pre-collapse states. If this distribution is wide, then the
composite surface density approaches a universal power-law form, independent of
the shape of the constituent profiles. When the angular momentum distribution
has an intermediate width, the composite surface density attains a nearly
exponential form, roughly consistent with profiles of observed galaxies.


title:
On the efficiency of particle acceleration by rotating magnetospheres in
  AGN

abstract:
  To investigate the efficiency of centrifugal acceleration of particles as a
possible mechanism for the generation of ultra-high $\gamma$-ray nonthermal
emission from TeV blazars, we study the centrifugal acceleration of electrons
by rotating magnetic field lines, for an extended range of inclination angles
and determine the maximum Lorentz factors $\gamma_{max}$ attainable by the
electrons via this process. {Two principal limiting mechanisms for the particle
acceleration, inverse Compton scattering and breakdown of the bead-on-the-wire
approximation, are examined. Particles may be centrifugally accelerated up to
$\gamma_{max} \simeq 10^8$ and the main limiting mechanism for the
$\gamma_{max}$ is the inverse Compton scattering. The energy of centrifugally
accelerated particles can be amply sufficient for the generation (via inverse
Compton scattering) of the ultra-high energy (up to $20TeV$) gamma emission in
TeV blazars.


title:
Swift/BAT and RXTE Observations of the Peculiar X-ray Binary 4U 2206+54
  - Disappearance of the 9.6 Day Modulation

abstract:
  Observations of the high-mass X-ray binary 4U 2206+54 with the Swift Burst
Alert Telescope (BAT) do not show modulation at the previously reported period
of 9.6 days found from observations made with the Rossi X-ray Timing Explorer
(RXTE) All-Sky Monitor (ASM). Instead, the strongest peak in the power spectrum
of the BAT light curve occurs at a period of 19.25 +/- 0.08 days, twice the
period found with the RXTE ASM. The maximum of the folded BAT light curve is
also delayed compared to the maximum of the folded ASM light curve. The most
recent ASM data folded on twice the 9.6 day period show similar morphology to
the folded BAT light curve. This suggests that the apparent period doubling is
a recent secular change rather than an energy-dependent effect. The 9.6 day
period is thus not a permanent strong feature of the light curve. We suggest
that the orbital period of 4U 2206+54 may be twice the previously proposed
value.


title: Evaluation of the ALMA Prototype Antennas

abstract:
  The ALMA North American and European prototype antennas have been evaluated
by a variety of measurement systems to quantify the major performance
specifications. Nearfield holography was used to set the reflector surfaces to
17 microns RMS. Pointing and fast switching performance was determined with an
optical telescope and by millimeter wavelength radiometry, yielding 2 arcsec
absolute and 0.6 arcsec offset pointing accuracies. Path length stability was
measured to be less than or approximately equal to 20 microns over 10 minute
time periods using optical measurement devices. Dynamical performance was
studied with a set of accelerometers, providing data on wind induced tracking
errors and structural deformation. Considering all measurements made during
this evaluation, both prototype antennas meet the major ALMA antenna
performance specifications.


title: Past and present star formation in the SMC: NGC 346 and its neighborhood

abstract:
  In the quest of understanding how star formation occurs and propagates in the
low metallicity environment of the Small Magellanic Cloud (SMC), we acquired
deep F555W (~V), and F814W (~I) HST/ACS images of the young and massive star
forming region NGC 346. These images and their photometric analysis provide us
with a snapshot of the star formation history of the region. We find evidence
for star formation extending from ~10 Gyr in the past until ~150 Myr in the
field of the SMC. The youngest stellar population (~3 +/- 1 Myr) is associated
with the NGC 346 cluster. It includes a rich component of low mass pre-main
sequence stars mainly concentrated in a number of sub-clusters, spatially co-
located with CO clumps previously detected by Rubio et al. (2000). Within our
analysis uncertainties, these sub-clusters appear coeval with each other. The
most massive stars appear concentrated in the central sub-clusters, indicating
possible mass segregation. A number of embedded clusters are also observed.
This finding, combined with the overall wealth of dust and gas, could imply
that star formation is still active. An intermediate age star cluster, BS90,
formed ~4.3 +/-0.1 Gyr ago, is also present in the region. Thus, this region of
the SMC has supported star formation with varying levels of intensity over much
of the cosmic time.


title: Balmer-Dominated Shocks Revisited

abstract:
  We present a new formalism to describe the ratios and profiles of emission
lines from hydrogen in Balmer-dominated shocks. We use this model to interpret
the measured widths and ratios of broad and narrow H-alpha, H-beta and Ly-alpha
emission lines in supernova remnants (SNRs). Our model results agree fairly
well with those obtained previously by Chevalier, Kirshner & Raymond (1980) and
are consistent with observations of several SNRs. The same model fails to
account for the ratio of broad to narrow line emission from the reverse shock
in SNR 1987A as observed by Heng et al. (2006). We suggest that this
discrepancy between theory and observation results from a faulty assumption
that Balmer-dominated shocks can be treated as sharp discontinuities. If the
spatial structure of the shock transition zone is taken into account, the
predicted ratios of broad to narrow line emission in most SNRs will change by
modest factors, but the ratio in SNR 1987A will increase substantially.
Significantly greater shock velocities will be required to account for the
observed full widths at half-maximum of the broad emission lines in most SNRs.


title:
The Signature of Primordial Grain Growth in the Polarized Light of the
  AU Mic Debris Disk

abstract:
  We have used the Hubble Space Telescope/ACS coronagraph to make polarization
maps of the AU Mic debris disk. The fractional linear polarization rises
monotonically from about 0.05 to 0.4 between 20 and 80 AU. The polarization is
perpendicular to the disk, indicating that the scattered light originates from
micron sized grains in an optically thin disk. Disk models, which
simultaneously fit the surface brightness and polarization, show that the inner
disk (< 40-50 AU) is depleted of micron-sized dust by a factor of more than
300, which means that the disk is collision dominated. The grains have high
maximum linear polarization and strong forward scattering. Spherical grains
composed of conventional materials cannot reproduce these optical properties. A
Mie/Maxwell-Garnett analysis implicates highly porous (91-94%) particles. In
the inner Solar System, porous particles form in cometary dust, where the
sublimation of ices leaves a "bird's nest" of refractory organic and silicate
material. In AU Mic, the grain porosity may be primordial, because the dust
"birth ring" lies beyond the ice sublimation point. The observed porosities
span the range of values implied by laboratory studies of particle coagulation
by ballistic cluster-cluster aggregation. To avoid compactification, the upper
size limit for the parent bodies is in the decimeter range, in agreement with
theoretical predictions based on collisional lifetime arguments. Consequently,
AU Mic may exhibit the signature of the primordial agglomeration process
whereby interstellar grains first assembled to form macroscopic objects.


title: The high-mass stellar IMF in different environments

abstract:
  The massive-star IMF is found to be invariable. However, integrated IMFs
probably depend on galactic mass.


title: Multiwavelength Mass Comparisons of the z~0.3 CNOC Cluster Sample

abstract:
  Results are presented from a detailed analysis of optical and X-ray
observations of moderate-redshift galaxy clusters from the Canadian Network for
Observational Cosmology (CNOC) subsample of the EMSS. The combination of
extensive optical and deep X-ray observations of these clusters make them ideal
candidates for multiwavelength mass comparison studies. X-ray surface
brightness profiles of 14 clusters with 0.17<z<0.55 are constructed from
Chandra observations and fit to single and double beta-models. Spatially
resolved temperature analysis is performed, indicating that five of the
clusters in this sample exhibit temperature gradients within their inner 60-200
kpc. Integrated spectra extracted within R_2500 provide temperature, abundance,
and luminosity information. Under assumptions of hydrostatic equilibrium and
spherical symmetry, we derive gas and total masses within R_2500 and R_200. We
find an average gas mass fraction within R_200 of 0.136 +/- 0.004, resulting in
Omega_m=0.28 +/- 0.01 (formal error). We also derive dynamical masses for these
clusters to R_200. We find no systematic bias between X-ray and dynamical
methods across the sample, with an average M(dyn)/M(X-ray) = 0.97 +/- 0.05. We
also compare X-ray masses to weak lensing mass estimates of a subset of our
sample, resulting in a weighted average of M(lens)/M(X-ray) of 0.99 +/- 0.07.
We investigate X-ray scaling relationships and find powerlaw slopes which are
slightly steeper than the predictions of self-similar models, with an E(z)^(-1)
Lx-Tx slope of 2.4 +/- 0.2 and an E(z) M_2500-Tx slope of 1.7 +/- 0.1.
Relationships between red-sequence optical richness (B_gc,red) and global
cluster X-ray properties (Tx, Lx and M_2500) are also examined and fitted.


title: TrES-2: The First Transiting Planet in the Kepler Field

abstract:
  We announce the discovery of the second transiting hot Jupiter discovered by
the Trans-atlantic Exoplanet Survey. The planet, which we dub TrES-2, orbits
the nearby star GSC 03549-02811 every 2.47063 days. From high-resolution
spectra, we determine that the star has T_eff = 5960 +/- 100 K and log(g) = 4.4
+/- 0.2, implying a spectral type of G0V and a mass of 1.08 +0.11/-0.05 M_sun.
High-precision radial-velocity measurements confirm a sinusoidal variation with
the period and phase predicted by the photometry, and rule out the presence of
line-bisector variations that would indicate that the spectroscopic orbit is
spurious. We estimate a planetary mass of 1.28 +0.09/-0.04 M_Jup. We model B,
r, R, and I photometric timeseries of the 1.4%-deep transits and find a
planetary radius of 1.24 +0.09/-0.06 R_Jup. This planet lies within the field
of view of the NASA Kepler mission, ensuring that hundreds of upcoming transits
will be monitored with exquisite precision and permitting a host of
unprecedented investigations.


title:
Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate
  of Short GRBs in Field and Cluster Early-Type Galaxies

abstract:
  We determine the relative rates of short GRBs in cluster and field early-type
galaxies as a function of the age probability distribution of their
progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the
difference in the growth of stellar mass in clusters and in the field, which
arises from the combined effects of the galaxy stellar mass function, the
early-type fraction, and the dependence of star formation history on mass and
environment. This approach complements the use of the early- to late-type host
galaxy ratio, with the added benefit that the star formation histories of
early-type galaxies are simpler than those of late-type galaxies, and any
systematic differences between progenitors in early- and late-type galaxies are
removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n =
-2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2,
corresponding to n ~ 0 - 1. This is similar to the value inferred from the
ratio of short GRBs in early- and late-type hosts, but it differs from the
value of n ~ -1 for NS binaries in the Milky Way. We stress that this general
approach can be easily modified with improved knowledge of the effects of
environment and mass on the build-up of stellar mass, as well as the effect of
globular clusters on the short GRB rate. It can also be used to assess the age
distribution of Type Ia supernova progenitors.


title:
Temporal Evolution of Coronagraphic Dynamic Range, and Constraints on
  Companions to Vega

abstract:
  The major obstacle to the direct detection of companions to nearby stars is
the overwhelming brightness of the host star. Current instruments employing the
combination of adaptive optics (AO) and coronagraphy can typically detect
objects within 2'' of the star that are 10^{4-5} times fainter. Correlated
speckle noise is one of the biggest obstacles limiting such high-contrast
imaging. We have obtained a series of 284 8 s, AO-corrected, coronagraphically
occulted H-band images of the star Vega at the 3.63 m AEOS telescope located on
Haleakala, Hawaii. This dataset is unique for studying the temporal behavior of
speckle noise, and represents the first time such a study on highly corrected
_coronagraphic_ AO images has been carried out in a quantitative way. We find
the speckle pattern to be highly stable in both position and time in our data.
This is due to the fact that the AO system corrects disturbances to the stellar
wave front at the level where the instrumental wave front errors dominate.
Because of this, we find that our detection limit is not significantly improved
simply with increased exposure time alone. However, we are able to improve our
dynamic range by 1.5-2 magnitudes through subtraction of static/quasi-static
speckles in two rotating frames: the telescope pupil frame and the deformable
mirror frame. Furthermore, from our data, we are able to constrain the mass of
any purported companion to Vega to be less than 45 M_J at 8 AU and less than 30
M_J at 16 AU, radii not previously probed at these sensitivities.


title: Color Tomography

abstract:
  Lensing tomography with multi-color imaging surveys can probe dark energy and
the cosmological power spectrum. However accurate photometric redshifts for
tomography out to high redshift require imaging in five or more bands, which is
expensive to carry out over thousands of square degrees. Since lensing makes
coarse, statistical use of redshift information, we explore the prospects for
tomography using limited color information from two or three band imaging. With
an appropriate calibration sample, we find that it is feasible to create up to
four redshift bins using imaging data in just the g, r and i bands. We
construct such redshift sub-samples from mock catalogs by clustering galaxies
in color space and discarding regions with poorly-defined redshift
distributions. The loss of galaxy number density decreases the accuracy of
lensing measurements, but even losing half or more of the galaxies is not a
severe loss for large area surveys. We estimate the errors on lensing power
spectra and dark energy parameters with color tomography and discuss trade-offs
in survey area and filter choice. We discuss the systematic errors that may
change our conclusions, especially the information needed to tackle intrinsic
alignments.


title: The Effect of Lensing on the Large-Scale CMB Anisotropy

abstract:
  We first compare the CMB lensing model of Seljak (1996) with the empirical
model of Lieu & Mittaz (2005) to determine if the latter approach implies a
larger effect on the CMB power-spectrum. We find that the empirical model gives
significantly higher results for the magnification dispersion, assuming
standard cosmological parameters. However, when the empirical foreground model
is modelled via correlation functions and used in the Seljak formalism, the
agreement is considerably improved. Thus we conclude that the main difference
may be in the assumed foregrounds. We then discuss a foreground mass
distribution which gives a lensing dispersion which is constant with angle. In
Seljak's formalism, we show this can lead to a smoothing of the CMB
power-spectrum which may be able to move the first acoustic peak to smaller l,
if the mass clustering amplitude is high enough. Evidence for such a high
amplitude comes from the QSO magnification results of Myers et al (2003, 2005)
who suggest that foreground galaxy groups may be more massive than expected,
implying that Omega_m ~ 1 and strong galaxy anti-bias. We then show that an
inflationary model with neither CDM nor a cosmological constant and that
predicts a primordial first peak at l=330 may fit the first acoustic peak of
the WMAP data. This fit may be regarded as somewhat contrived since it also
requires high redshift reionisation at the upper limit of what is allowed by
the WMAP results. But given the finely-tuned nature of the standard LCDM model,
the contrivance may be small in comparison and certainly the effect of lensing
and other foregrounds may still have a considerable influence on the
cosmological interpretation of the CMB.


title:
Multi-site campaign on the open cluster M67. I. Observations and
  photometric reductions

abstract:
  We report on an ambitious multi-site campaign aimed at detecting stellar
variability, particularly solar-like oscillations, in the red giant stars in
the open cluster M67 (NGC 2682). During the six-week observing run, which
comprised 164 telescope nights, we used nine 0.6-m to 2.1-m class telescopes
located around the world to obtain uninterrupted time-series photometry. We
outline here the data acquisition and reduction, with emphasis on the
optimisation of the signal-to-noise of the low amplitude (50-500 micromag)
solar-like oscillations. This includes a new and efficient method for obtaining
the linearity profile of the CCD response at ultra high precision (~10 parts
per million). The noise in the final time series is 0.50 mmag per minute
integration for the best site, while the noise in the Fourier spectrum of all
sites combined is 20 micromag. In addition to the red giant stars, this data
set proves to be very valuable for studying high-amplitude variable stars such
as eclipsing binaries, W UMa systems and delta Scuti stars.


title: GEO debris and interplanetary dust: fluxes and charging behavior

abstract:
  In September 1996, a dust/debris detector: GORID was launched into the
geostationary (GEO) region as a piggyback instrument on the Russian Express-2
telecommunications spacecraft. The instrument began its normal operation in
April 1997 and ended its mission in July 2002. The goal of this work was to use
GORID's particle data to identify and separate the space debris to
interplanetary dust particles (IDPs) in GEO, to more finely determine the
instrument's measurement characteristics and to derive impact fluxes. While the
physical characteristics of the GORID impacts alone are insufficient for a
reliable distinction between debris and interplanetary dust, the temporal
behavior of the impacts are strong enough indicators to separate the
populations based on clustering. Non-cluster events are predominantly
interplanetary, while cluster events are debris. The GORID mean flux
distributions (at mass thresholds which are impact speed dependent) for IDPs,
corrected for dead time, are 1.35x10^{-4} m^{-2} s^{-1} using a mean detection
rate: 0.54 d^{-1}, and for space debris are 6.1x10^{-4} m^{-2} s^{-1} using a
mean detection rate: 2.5 d^{-1}. Beta-meteoroids were not detected. Clusters
could be a closely-packed debris cloud or a particle breaking up due to
electrostatic fragmentation after high charging.


title: On the two-dimensional magnetic reconnection with nonuniform resistivity

abstract:
  In this paper two theoretical approaches for the calculation of the rate of
quasi-stationary, two-dimensional magnetic reconnection with nonuniform
anomalous resistivity are considered in the framework of incompressible
magnetohydrodynamics (MHD). In the first, ``global'' equations approach the MHD
equations are approximately solved for a whole reconnection layer, including
the upstream and downstream regions and the layer center. In the second,
``local'' equations approach the equations are solved across the reconnection
layer, including only the upstream region and the layer center. Both approaches
give the same approximate answer for the reconnection rate. Our theoretical
model is in agreement with the results of recent simulations of reconnection
with spatially nonuniform resistivity by Baty, Priest and Forbes (2006),
contrary to their conclusions.


title:
The Near-infrared S0 Survey III: Morphology of 15 Southern Early-type
  Disk Galaxies

abstract:
  Structural analysis has been performed for a sample of 15 Southern early-type
disk galaxies, mainly S0s, using high resolution $K_s$-band images. The
galaxies are mostly barred and many of them show multiple structures including
bars and ovals, typical for S0s. The new images are of sufficient quality to
reveal new detail on the morphology of the galaxies. For example, we report a
hitherto undetected nuclear ring in NGC 1387, a nuclear bar in NGC 1326, and in
the residual image also a weak primary bar in NGC 1317. For the galaxies we (1)
measure the radial profiles of the orientation parameters derived from the
elliptical isophotes, (2) apply Fourier methods for calculating tangential
forces, and particularly, (3) apply structural decomposition methods. For
galaxies with multiple structures a 2-dimensional method is found to be
superior to a 1-dimensional method, but only if in addition to the bulge and
the disk, at least one other component is taken into account. {\it We find
strong evidence of pseudo-bulges in S0s}: ten of the galaxies have the shape
parameter of the bulge near to $n$ = 2, indicating that the bulges are more
disk-like than following the R$^{1/4}$-law. Also, six of the galaxies have
either nuclear rings, nuclear bars or nuclear disks. In all non-elliptical
galaxies in our sample the $B/T < $ 0.4, as typically found in galaxies having
pseudo-bulges. In two of the galaxies the $B/T$ flux ratio is as small as in
typical Sc-type spirals. This might be the hitherto undiscovered link in the
scenario in which spirals are transformedinto S0s. Also, bars in S0s are found
to be shorter and less massive, and have smaller bar torques than bars in
S0/a-type galaxies.


title:
General Relativistic Magnetohydrodynamic Simulations of Jet Formation
  with a Thin Keplerian Disk

abstract:
  We have performed several simulations of black hole systems (non-rotating,
black hole spin parameter a=0.0 and rapidly rotating, a=0.95) with a
geometrically thin Keplerian disk using the newly developed RAISHIN code. The
simulation results show the formation of jets driven by the Lorentz force and
the gas pressure gradient. The jets have mildly relativistic speed (\sim 0.4c).
The matter is continuously supplied from the accretion disk and the jet
propagates outward until each applicable terminal simulation time
(non-rotating: t/\tau_S = 275 and rotating: t/tau_S = 200, \tau_S \equiv
r_S/c). It appears that a rotating black hole creates an additional, faster,
and more collimated matter-dominated inner outflow (\sim 0.5c) formed and
accelerated by the twisted magnetic field resulting from frame-dragging in the
black hole ergosphere. This is the first known simulation confirming the
formation of an inner magnetically-driven, matter-dominated jet by the
frame-dragging effect from a black hole co-rotating with a thin Keplerian disk
threaded by a vertical magnetic field. This result indicates that jet kinematic
structure depends on black hole rotation and on the initial magnetic field
configuration and strength.


title: Kinematic frames and "active longitudes": does the Sun have a face?

abstract:
  It has recently been claimed that analysis of Greenwich sunspot data over 120
years reveals that sunspot activity clusters around two longitudes separated by
180 degrees (``active longitudes'') with clearly defined differential rotation
during activity cycles.In the present work we extend this critical examination
of methodology to the actual Greenwich sunspot data and also consider newly
proposed methods of analysis claiming to confirm the original identification of
active longitudes. Our analysis revealed that values obtained for the
parameters of differential rotation are not stable across different methods of
analysis proposed to track persistent active longitudes. Also, despite a very
thorough search in parameter space, we were unable to reproduce results
claiming to reveal the century-persistent active longitudes. We can therefore
say that strong and well substantiated evidence for an essential and
century-scale persistent nonaxisymmetry in the sunspot distribution does not
exist.


title:
Discovery of hard X-ray delays in the X-ray emission of the Seyfert 1
  galaxy Mrk~110: possible evidence for Comptonization

abstract:
  We report the discovery of hard X-ray delays in the X-ray emission of the
Seyfert 1 galaxy Mrk 110, based on a long XMM-Newton observation. Cross
correlation between the X-ray light curves of different energy bands reveals an
energy dependent delay ranging from a few minutes to an hour. We find that the
energy spectrum can be modeled by Comptonization of disk blackbody photons. The
energy dependent delay can be modeled as due to the effect of Comptonization in
a hot plasma confined within 10 Schwarzschild radius of the black hole. We
discuss our results in the context of inverse Comptonization of the soft
photons by highly energetic plasma.


title: Electron acceleration in relativistic GRB shocks

abstract:
  The shock model of gamma-ray bursts (GRBs) contains two equipartition
parameters: the magnetic energy density and the kinetic energy density of the
electrons relative to the total energy density of the shock, "epsilon_B" and
"epsilon_e", respectively. These are free parameters within the model. Whereas
the Weibel shock theory and numerical simulations fix "epsilon_B" at the level
of ~few times(10^{-3}...10^{-4}), no understanding of "epsilon_e" exists so
far. Here we demonstrate that it inevitably follows from the theory that
"epsilon_e"~(epsilon_B)^(1/2). The GRB afteglow data fully agree with this
theoretical prediction. Our result explains why the electrons are close to
equipartition in GRBs. The "epsilon_e"-"epsilon_B" relation can potentially be
used to reduce the number of free parameters in afterglow models.


title:
Statistical analysis of undetected point sources in cosmic microwave
  background maps

abstract:
  Cosmic microwave background (CMB) temperature anisotropies follow a Gaussian
statistical distribution in the standard inflationary model, but there are
non-Gaussian contributions due to astrophysical foregrounds. The detection of
the non-Gaussian signal due to extragalactic point sources and its distinction
from the possible intrinsic non-Gaussianity is an issue of great importance in
CMB analysis. The Mexican Hat Wavelet Family (MHWF), which has been proved very
useful for the detection of extragalactic point sources, is applied here to the
study of non-Gaussianity due to point sources in CMB maps. We carry out
simulations of CMB maps with the characteristics of the forthcoming Planck
mission at 70 and 100 GHz and filter them with the MHWF. By comparing the
skewness and kurtosis of simulated maps with and without point sources, we are
able to detect clearly the non-Gaussian signal due to point sources for flux
limits as low as 0.4 Jy (70 GHz) and 0.3 Jy (100 GHz). The second and third
members of the MHWF perform better in this respect than the Mexican Hat Wavelet
(MHW1) and much better than the Daubechies 4 wavelet. We have also estimated
the third order, $K_3$, and fourth order, $K_4$, cumulants produced by point
sources at these Planck channels by means of a fit with the MHWF. The average
relative errors with respect to the real values are below 12% for fluxes down
to 0.6 Jy (70 GHz) and 0.4 Jy (100 GHz). The values of these cumulants allow us
to distinguish between different source counts models.


title: Imprint of spatial curvature on inflation power spectrum

abstract:
  If the universe had a large curvature before inflation there is a deviation
from the scale invariant perturbations of the inflaton at the beginning of
inflation. This may have some effect on the CMB anisotropy at large angular
scales. We calculate the density perturbations for both open and closed
universe cases using the Bunch-Davies vacuum condition on the initial state. We
use our power spectrum to calculate the temperature anisotropy spectrum and
compare the results with the WMAP three year data. We find that our power
spectrum gives a lower quadrupole anisotropy when $\Omega-1 >0$, but matches
the temperature anisotropy calculated from the standard Ratra-Peebles power
spectrum at large $l$. The determination of spatial curvature from temperature
anisotropy data is not much affected by the different power spectra which arise
from the choice of different boundary conditions for the inflaton perturbation.


title: Effects of Rotation and Input Energy Flux on Convective Overshooting

abstract:
  We study convective overshooting by means of local 3D convection
calculations. Using a mixing length model of the solar convection zone (CZ) as
a guide, we determine the Coriolis number (Co), which is the inverse of the
Rossby number, to be of the order of ten or larger at the base of the solar CZ.
Therefore we perform convection calculations in the range Co = 0...10 and
interpret the value of Co realised in the calculation to represent a depth in
the solar CZ. In order to study the dependence on rotation, we compute the
mixing length parameters alpha_T and alpha_u relating the temperature and
velocity fluctuations, respectively, to the mean thermal stratification. We
find that the mixing length parameters for the rapid rotation case,
corresponding to the base of the solar CZ, are 3-5 times smaller than in the
nonrotating case. Introducing such depth-dependent alpha into a solar structure
model employing a non-local mixing length formalism results in overshooting
which is approximately proportional to alpha at the base of the CZ. Although
overshooting is reduced due to the reduced alpha, a discrepancy with
helioseismology remains due to the steep transition to the radiative
temperature gradient. In comparison to the mixing length models the transition
at the base of the CZ is much gentler in the 3D models. It was suggested
recently (Rempel 2004) that this discrepancy is due to the significantly larger
(up to seven orders of magnitude) input energy flux in the 3D models in
comparison to the Sun and solar models, and that the 3D calculations should be
able to approach the mixing length regime if the input energy flux is decreased
by a moderate amount. We present results from local convection calculations
which support this conjecture.


title: Wavelets on the sphere. Application to the detection problem

abstract:
  A new method is presented for the construction of a natural continuous
wavelet transform on the sphere. It incorporates the analysis and synthesis
with the same wavelet and the definition of translations and dilations on the
sphere through the spherical harmonic coefficients. We construct a couple of
wavelets as an extension of the flat Mexican Hat Wavelet to the sphere and we
apply them to the detection of sources on the sphere. We remark that no
projections are used with this methodology.


title: Accelerated-like expansion: inhomogeneities versus dark energy

abstract:
  The currently available cosmological data yield, as a most striking result,
that the expansion rate of the universe seems to be increasing at late times,
contrary to the standard (zero cosmological constant) FLRW prediction. The
usual explanation for this discrepancy is that a new component of the energy
density of the universe, known as dark energy, dominates this recent evolution.
Since the existence of such a new component would have a revolutionary impact
on our understanding of the fundamental laws of physics, we think important to
check other interpretations. We have therefore shown that the SNIa observations
could be reproduced by the effect of inhomogeneities. This idea has been
further developed by different teams, and enlarged to other cosmological data.
We will give here a review of the results of these works and the prospects for
future developments.


title: Integrated Light 2MASS IR Photometry of Galactic Globular Clusters

abstract:
  We have mosaiced 2MASS images to derive surface brightness profiles in JHK
for 104 Galactic globular clusters. We fit these with King profiles, and show
that the core radii are identical to within the errors for each of these IR
colors, and are identical to the core radii at V in essentially all cases. We
derive integrated light colors V-J, V-H, V-K_s, J-H and J-K_s for these
globular clusters. Each color shows a reasonably tight relation between the
dereddened colors and metallicity. Fits to these are given for each color. The
IR--IR colors have very small errors due largely to the all-sky photometric
calibration of the 2MASS survey, while the V-IR colors have substantially
larger uncertainties. We find fairly good agreement with measurements of
integrated light colors for a smaller sample of Galactic globular clusters by
Aaronson, Malkan & Kleinmann from 1977. Our results provide a calibration for
the integrated light of distant single burst old stellar populations from very
low to Solar metallicities. A comparison of our dereddened measured colors with
predictions from several models of the integrated light of single burst old
populations shows good agreement in the low metallicity domain for V-K_s
colors, but an offset at a fixed [Fe/H] of ~0.1 mag in J-K_s, which we ascribe
to photometric system transformation issues. Some of the models fail to
reproduce the behavior of the integrated light colors of the Galactic globular
clusters near Solar metallicity.


title:
Probing Dark Energy with Baryonic Acoustic Oscillations at High
  Redshifts

abstract:
  The phases as well as the amplitudes of baryonic acoustic oscillations can be
extracted out of a galaxy power spectrum and used as a standard ruler in a
cosmological test. A non-oscillating phenomenological fitting function is used
to extract the oscillatory part of the galaxy power spectrum and to disentangle
phase information from amplitude information. The method (FITEX) is tested with
simulated data of the Hubble Volume Simulation to include redshift space
effects, non-linear structure growth and biasing. A cosmological test is
introduced, which compares the extracted oscillations against a theoretical
model template to derive constraints on the $w$ parameter.
  The phenomenological fitting function is found to model the various
distortions of the galaxy power spectrum to the sub-percent level. The various
distortions only boost the amplitude of the oscillations. The theoretical
template is accurate enough to test for small deviations in the phases of the
oscillations, resulting from different $w$ values. A cosmological test, using
the baryonic acoustic oscillations as a standard ruler, is able to constrain
$w$ in a robust way.


title:
A possible bias on the estimate of Lbol/Ledd in AGN as a function of
  luminosity and redshift

abstract:
  The BH mass (and the related Eddington ratio) in broad line AGN is usually
evaluated by combining estimates (often indirect) of the BLR radius and of the
FWHM of the broad lines, under the assumption that the BLR clouds are in
Keplerian motion around the BH. Such an evaluation depends on the geometry of
the BLR. There are two major options for the BLR configuration: spherically
symmetric or ``flattened''. In the latter case the inclination to the line of
sight becomes a relevant parameter. This paper is devoted to evaluate the bias
on the estimate of the Eddington ratio when a spherical geometry is assumed
(more generally when inclination effects are ignored), while the actual
configuration is ``flattened'', as some evidence suggests. This is done as a
function of luminosity and redshift, on the basis of recent results which show
the existence of a correlation between the fraction of obscured AGN and these
two parameters up to at least z=2.5. The assumed BLR velocity field is akin to
the ``generalized thick disk'' proposed by Collin et al. (2006). Assuming an
isotropic orientation in the sky, the mean value of the bias is calculated as a
function of luminosity and redshift. It is demonstrated that, on average, the
Eddington ratio obtained assuming a spherical geometry is underestimated for
high luminosities, and overestimated for low luminosities. This bias converges
for all luminosities at z about 2.7, while nothing can be said on this bias at
larger redshifts due to the lack of data. The effects of the bias, averaged
over the luminosity function of broad line AGN, have been calculated. The
results imply that the bias associated with the a-sphericity of the BLR make
even worse the discrepancy between the observations and the predictions of
evolutionary models.


title:
Discovery of 9 New Companions to Nearby Young M Stars with the Altair AO
  System

abstract:
  We present results of a high-resolution, near-infrared survey of 41 nearby,
young (<~300 Myr) M0-M5.0 dwarfs using the Altair natural guide star adaptive
optics system at the Gemini North telescope. Twelve of the objects appear to be
binaries, 7 of which are reported here for the first time. One triple system
was discovered. Statistical properties are studied and compared with earlier (F
to K) and later (>= M6 very low-mass, VLM) populations. We find that the
separation distribution of the binaries in this sample peaks at 13+14-9 AU,
which is consistent with previous measurements of early-M binaries. Hence,
early-M binaries seem to occur in--on average--tighter systems than G binaries.
At the same time they are significantly wider than field VLM binary stars. The
distribution of mass ratios q of primary and secondary stars was found to show
an intermediate distribution between the strongly q-->1 peaked distribution of
field VLM systems and the almost flat distribution of earlier-type stars.
Consequently, we show evidence for relatively young, early-M binaries
representing a transition between the well known earlier star distributions and
the recently examined field VLM population characteristics. Despite the fact
that this survey was dedicated to the search for faint brown dwarf and
planetary mass companions, all planetary mass candidates were background
objects. We exclude the existence of physical companions with masses greater
than 10 Jupiter masses (M_Jup) at separations of >~40 AU and masses greater
than 24 M_Jup for separations >~10 AU around 37 of the 41 observed objects.


title: The orbits of 48 globular clusters in a Milky-Way-Like Barred Galaxy

abstract:
  The effect of a barred potential (such as the one of the Milky Way) on the
galactic orbits of forty-eight globular clusters for which absolute proper
motions are known is studied. The orbital characteristics are compared with
those obtained for the case of an axisymmetric galactic potential. Tidal radii
are computed and discussed for both the better known axisymmetric case and that
including a bar. The destruction rates due to bulge and disk shocking are
calculated and compared in both galactic potentials.


title: The Impact of Stochastic Attenuation on Photometric Redshift Estimates

abstract:
  We model the attenuation due to HI along a random line of sight (LOS) using
differential distribution functions constrained from observations (Kim et al.
97) in a Monte Carlo fashion (Bershady et al. 99) as described in Tepper Garcia
& Fritze-v.A. (in prep.). We generate an ensemble of thousands of lines of
sight out to a given redshift z, each of them containing a random absorber
population. For each LOS we calculate an absorption mask, i.e. we compute the
photoelectric and Lyman-Series line absorption (as yet just for the first five
Lyman transitions) caused by each absorber for a flat input spectrum, modeling
line profiles as in Tepper Garcia 2006. We compute model galaxy spectra
corresponding to a CSFR for redshifts in the range 0.0 < z < 4.5 using the
Evolutionary Synthesis code GALEV (Bicker et al. 2004). For a given redshift,
we multiply each of the masks with our input spectrum and thus obtain an
ensemble of an equal number of attenuated spectra. For each of these we compute
a SED in the Johnson system. Using AnalySED (Anders et al. 2006) and a set of
template SEDs that include only the mean attenuation (Madau 95) for every
redshift, we determine to which extent the redshifts of our simulated spectral
energy distributions are recovered.


title: Source population synthesis and the Galactic diffuse gamma-ray emission

abstract:
  Population synthesis is used to study the contribution from undetected
sources to the Galactic ridge emission measured by EGRET. Synthesized source
counts are compared with the 3rd EGRET catalogue at low and high latitudes. For
pulsar-like populations, 5-10% of the emission >100 MeV comes from sources
below the EGRET threshold. A steeper luminosity function can increase this to
20% without violating EGRET source statistics. Less luminous populations can
produce much higher values without being detected. Since the unresolved source
spectrum is different from the interstellar spectrum, it could provide an
explanation of the observed MeV and GeV excesses above the predictions, and we
give an explicit example of how this could work.


title:
Connection between the Age Distributions of Star Clusters and Field
  Stars: A First Application to the Small Magellanic Cloud

abstract:
  We present the age distributions for star clusters and individual stars in
the Small Magellanic Cloud (SMC) based on data from the Magellanic Clouds
Photometric Survey by Zaritsky and collaborators. The age distribution of the
SMC clusters shows a steep decline, dN_{cluster}/dt \propto t^{-0.85\pm0.15},
over the period 10^7 < t <10^9 yr. This decline is essentially identical to
that observed previously for more massive clusters in the merging Antennae
galaxies, and also for lower-mass embedded clusters in the solar neighborhood.
The SMC cluster age distribution therefore provides additional evidence for the
rapid disruption of star clusters (``infant mortality''). These disrupted
clusters deliver their stars to the general field population, implying that the
field star age distribution, dN_{fld star}/dt, should have an inverse relation
to dN_{cluster}/dt if most stars form initially in clusters. We make specific
predictions for dN_{fldstar}/dt based on our cluster disruption models, and
compare them with current data available for stars in the SMC. While these data
do not extend to sufficiently young ages for a definitive test, they are
consistent with a scenario wherein most SMC stars formed in clusters. Future
analyses of dN_{fldstar}/dt that extend down to ages of approximately few
million years are needed to verify the age relationship between stars residing
in clusters and in the field.


title: Triaxial vs. Spherical Dark Matter Halo Profiles

abstract:
  When analysing dark matter halos forming in cosmological N-body simulations
it is common practice to obtain the density profile utilizing spherical shells.
However, it is also known that the systems under investigation are far from
spherical symmetry and rather follow a triaxial mass distribution. In this
study we present an estimator for the error introduced by spherically averaging
an elliptical mass distribution. We systematically investigate the differences
arising when using a triaxial density profile under the assumption of spherical
symmetry. We show that the variance in the density can be as large as 50% in
the outer parts of dark matter halos for extreme (but still credible) axis
ratios of 0.55:0.67:1. The inner parts are less affected but still show a
scatter at the 16% level for these prolate systems. For more moderate
ellipticities, i.e. axis ratios of 0.73:0.87:1, the error is smaller but still
as large as 10-20% depending on distance. We further provide a simple formula
that allows to estimate this variance as a function of radius for arbitrary
axis ratios. We conclude that highly prolate and/or oblate systems are better
fit by analytical profiles that take into account the triaxial nature of
cosmological objects.


title: High dynamic range imaging by pupil single-mode filtering and remapping

abstract:
  Because of atmospheric turbulence, obtaining high angular resolution images
with a high dynamic range is difficult even in the near infrared domain of
wavelengths. We propose a novel technique to overcome this issue. The
fundamental idea is to apply techniques developed for long baseline
interferometry to the case of a single-aperture telescope. The pupil of the
telescope is broken down into coherent sub-apertures each feeding a single-mode
fiber. A remapping of the exit pupil allows interfering all sub-apertures
non-redundantly. A diffraction-limited image with very high dynamic range is
reconstructed from the fringe pattern analysis with aperture synthesis
techniques, free of speckle noise. The performances of the technique are
demonstrated with simulations in the visible range with an 8 meter telescope.
Raw dynamic ranges of 1:$10^6$ can be obtained in only a few tens of seconds of
integration time for bright objects.


title: Early evolution of Tidal Dwarf Galaxies

abstract:
  Our aim is to study the evolution of tidal dwarf galaxies. The first step is
to understand whether a model galaxy without Dark Matter can sustain the
feedback of the ongoing star formation. We present tests of the evolution of
models in which star formation efficiency, temperature threshold, initial
distribution of gas and infall are varied. We conclude that it is feasible to
keep a fraction of gas bound for several hundreds of Myr and that the
development of galactic winds does not necessarily stop continuous star
formation.


title: Magnetar oscillations pose challenges for strange stars

abstract:
  Compact relativistic stars allow us to study the nature of matter under
extreme conditions, probing regions of parameter space that are otherwise
inaccessible. Nuclear theory in this regime is not well constrained: one key
issue is whether neutron stars are in fact composed primarily of strange quark
matter. Distinguishing the two possibilities, however, has been difficult. The
recent detection of seismic vibrations in the aftermath of giant flares from
two magnetars (highly magnetized compact stars) is a major breakthrough. The
oscillations excited seem likely to involve the stellar crust, the properties
of which differ dramatically for strange stars. We show that the resulting mode
frequencies cannot be reconciled with the observations for reasonable magnetar
parameters. Ruling out strange star models would place a strong constraint on
models of dense quark matter.


title:
Line-of-sight velocity distributions of elliptical galaxies from
  collisionless mergers

abstract:
  We analyse the skewness of the line-of-sight velocity distributions in model
elliptical galaxies built through collisionless galaxy mergers. We build the
models using large N-body simulations of mergers between either two spiral or
two elliptical galaxies. Our aim is to investigate whether the observed ranges
of skewness coefficient (h3) and the rotational support (V/sigma), as well as
the anticorrelation between h3 and V, may be reproduced through collisionless
mergers. Previous attempts using N-body simulations failed to reach V/sigma ~
1-2 and corresponding high h3 values, which suggested that gas dynamics and
ensuing star formation might be needed in order to explain the skewness
properties of ellipticals through mergers. Here we show that high V/sigma and
high h3 are reproduced in collisionless spiral-spiral mergers whenever a
central bulge allows the discs to retain some of their original angular
momentum during the merger. We also show that elliptical-elliptical mergers,
unless merging from a high-angular momentum orbit, reproduce the strong
skewness observed in non-rotating, giant, boxy ellipticals. The behaviour of
the h3 coefficient therefore associates rapidly-rotating disky ellipticals to
disc-disc mergers, and associates boxy, slowly-rotating giant ellipticals to
elliptical-elliptical mergers, a framework generally consistent with the
expectations of hierarchical galaxy formation.


title:
A near-infrared spectroscopic detection of the brown dwarf in the post
  common envelope binary WD0137-349

abstract:
  We present a near-infrared spectrum of the close, detached white dwarf +
brown dwarf binary WD0137-349 (Maxted et al 2006), that directly reveals the
substellar companion through an excess of flux longwards of 1.95 microns. We
best match the data with a white dwarf + L8 composite model. For ages ~1 Gyr,
the spectral type of the cool secondary is in agreement with the mass
determined by Maxted et al. (2006) from radial velocity measurements (0.053 +/-
0.006Msun), and supports an evolutionary scenario in which the brown dwarf
survived a previous phase of common envelope evolution which resulted in the
formation of this close binary. The brown dwarf is the lowest mass companion to
a white dwarf yet found, and the lowest mass object known to have survived a
common envelope phase. At 1300 < T < 1400K WD0137-349B is also the coolest
known companion to a white dwarf. At a separation a = 0.65Rsun the hemisphere
of the brown dwarf facing the 16,500K white dwarf is being heated through
irradiation. We discuss the possible effects of this additional heating, with
particular relevance to those other close binaries with substellar companions,
the hot Jupiters. We propose future observations to investigate the likely
temperature differences between the ``day'' and ``night'' sides of the brown
dwarf.


title: Diagnostics of the black hole candidate SS433 with the RXTE

abstract:
  We present our analysis of the extensive monitoring of SS433 by the RXTE
observatory collected over the period 1996-2005. The difference between energy
spectra taken at different precessional and orbital phases shows the presence
of strong photoabsorption (N_H>10^{23}cm^{-2}) near the optical star, probably
due to its powerful, dense wind. Therefore the size of the secondary deduced
from analysis of X-ray orbital eclipses might be significantly larger than its
Roche lobe size, which must be taken into account when evaluating the mass
ratio from analysis of X-ray eclipses. Assuming that a precessing accretion
disk is geometrically thick, we recover the temperature profile in the X-ray
emitting jet that best fits the observed precessional variations in the X-ray
emission temperature. The hottest visible part of the X-ray jet is located at a
distance of l_0/a~0.06-0.09, or ~2-3*10^{11}cm from the central compact object,
and has a temperature of about T_{max}~30 keV. We discovered appreciable
orbital X-ray eclipses at the ``crossover'' precessional phases (jets are in
the plane of the sky, disk is edge-on), which under model assumptions put a
lower limit on the size of the optical component R/a>0.5 and an upper limit on
a mass ratio of binary companions q=M_x/M_{opt}<0.3-0.35, if the X-ray opaque
size of the star is not larger than 1.2R_{Roche, secondary}.


title: Using polarization to study the winds of massive stars

abstract:
  The topic of wind-clumping has been the subject of much activity in recent
years, due to the impact that it can have on derived mass-loss rates. Here we
present an alternative method of investigating wind-clumping, that of
polarimetry. We present simulations of the polarization produced by a clumpy
wind, and argue that the observations may be reproduced just by statistical
deviations from spherical symmetry when the outflow is only slightly
fragmented. Here, the polarization scales with $\dot{M}$, which is consistent
with observations of LBVs, WRs and O supergiants. Finally, we find clumping
factors in the inner 2$R_{\star}$ of $\sim 2-3$, and speculate as to the
clumping stratification of hot stars.


title:
HAT-P-1b: A Large-Radius, Low-Density Exoplanet Transiting one Member of
  a Stellar Binary

abstract:
  Using small automated telescopes in Arizona and Hawaii, the HATNet project
has detected an object transiting one member of the double star system ADS
16402 AB. This system is a pair of G0 main-sequence stars with age about 3 Gyr
at a distance of ~139 pc and projected separation of ~1550 AU. The transit
signal has a period of 4.46529 days and depth of 0.015 mag. From follow-up
photometry and spectroscopy, we find that the object is a "hot Jupiter" planet
with mass about 0.53 M_jup and radius ~1.36 R_jup traveling in an orbit with
semimajor axis 0.055 AU and inclination about 85.9 deg, thus transiting the
star at impact parameter 0.74 of the stellar radius. Based on a data set
spanning three years, ephemerides for the transit center are: T_C = 2453984.397
+ N_tr * 4.46529. The planet, designated HAT-P-1b, appears to be at least as
large in radius, and smaller in mean density, than any previously-known planet.


title: The birth and early evolution of star clusters

abstract:
  Star clusters are observed to form in a highly compact state and with low
star-formation efficiencies, and only 10 per cent of all clusters appear to
survive to middle- and old-dynamical age. If the residual gas is expelled on a
dynamical time the clusters disrupt. Massive clusters may then feed a hot
kinematical stellar component into their host-galaxy's field population thereby
thickening galactic disks, a process that theories of galaxy formation and
evolution need to accommodate. If the gas-evacuation time-scale depends on
cluster mass, then a power-law embedded-cluster mass function may transform
within a few dozen Myr to a mass function with a turnover near 10^5 Msun,
thereby possibly explaining this universal empirical feature. Discordant
empirical evidence on the mass function of star clusters leads to the insight
that the physical processes shaping early cluster evolution remain an issue of
cutting-edge research.


title:
Trends in the Globular Cluster Luminosity Function of Early-Type
  Galaxies

abstract:
  We present results from a study of the globular cluster luminosity function
(GCLF) in a sample of 89 early-type galaxies observed as part of the ACS Virgo
Cluster Survey. Using a Gaussian parametrization of the GCLF, we find a highly
significant correlation between the GCLF dispersion, sigma, and the galaxy
luminosity, M_B, in the sense that the GC systems in fainter galaxies have
narrower luminosity functions. The GCLF dispersions in the Milky Way and M31
are fully consistent with this trend, implying that the correlation between
sigma and galaxy luminosity is more fundamental than older suggestions that
GCLF shape is a function of galaxy Hubble type. We show that the sigma - M_B
relation results from a bonafide narrowing of the distribution of (logarithmic)
cluster masses in fainter galaxies. We further show that this behavior is
mirrored by a steepening of the GC mass function for relatively high masses, M
>~ 3 x 10^5 M_sun, a mass regime in which the shape of the GCLF is not strongly
affected by dynamical evolution over a Hubble time. We argue that this trend
arises from variations in initial conditions and requires explanation by
theories of cluster formation. Finally, we confirm that in bright galaxies, the
GCLF "turns over" at the canonical mass scale of M_TO ~ 2 x 10^5 M_sun.
However, we find that M_TO scatters to lower values (~1-2 x 10^5 M_sun) in
galaxies fainter than M_B >~ -18.5, an important consideration if the GCLF is
to be used as a distance indicator for dwarf ellipticals.


title:
Evidence for Mass-dependent Circumstellar Disk Evolution in the 5
  Myr-old Upper Scorpius OB Association

abstract:
  We present 4.5, 8, and 16um photometry from the Spitzer Space Telescope for
204 stars in the Upper Scorpius OB Association. The data are used to
investigate the frequency and properties of circumstellar disks around stars
with masses between ~ 0.1 and 20 Msun at an age of ~ 5 Myr. We identify 35
stars that have emission at 8um or 16um in excess of the stellar photosphere.
The lower mass stars (~ 0.1-1.2 Msun) appear surrounded by primordial optically
thick disks based on the excess emission characteristics. Stars more massive
than ~ 1.8 Msun have lower fractional excess luminosities suggesting that the
inner ~ 10 AU of the disk has been largely depleted of primordial material.
None of the G and F stars (~ 1.2-1.8 Msun) in our sample have an infrared
excess at wavelengths <= 16um. These results indicate that the mechanisms for
dispersing primordial optically thick disks operate less efficiently on average
for low mass stars, and that longer time scales are available for the buildup
of planetary systems in the terrestrial zone for stars with masses < 1 Msun.


title:
ARCADE: Absolute Radiometer for Cosmology, Astrophysics, and Diffuse
  Emission

abstract:
  The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission
(ARCADE) is a balloon-borne instrument designed to measure the temperature of
the cosmic microwave background at centimeter wavelengths. ARCADE searches for
deviations from a blackbody spectrum resulting from energy releases in the
early universe. Long-wavelength distortions in the CMB spectrum are expected in
all viable cosmological models. Detecting these distortions or showing that
they do not exist is an important step for understanding the early universe. We
describe the ARCADE instrument design, current status, and future plans.


title: The MicroJansky Radio Galaxy Population

abstract:
  We use highly spectroscopically complete observations of the radio sources
from the VLA 1.4 GHz survey of the HDF-N region to study the faint radio galaxy
population and its evolution. We spectrally classify the sources into four
spectral types: absorbers, star formers, Seyfert galaxies, and broad-line AGNs,
and we analyze their properties by type. We supplement the spectroscopic
redshifts with photometric redshifts measured from the rest-frame UV to MIR
spectral energy distributions. Using deep X-ray observations of the field, we
do not confirm the existence of an X-ray-radio correlation for star-forming
galaxies. We also do not observe any correlations between 1.4 GHz flux and R
magnitude or redshift. We find that the radio powers of the host galaxies rise
dramatically with increasing redshift, while the optical properties of the host
galaxies show at most small changes. Assuming that the locally determined
FIR-radio correlation holds at high redshifts, we estimate total FIR
luminosities for the radio sources. We note that the FIR luminosity estimates
for any radio-loud AGNs will be overestimates. Considering only the radio
sources with quasar-like bolometric luminosities, we find a maximum ratio of
candidate highly-obscured AGNs to X-ray-luminous (>10^42 ergs/s) sources of
about 1.9. We use source-stacking analyses to measure the X-ray surface
brightnesses of various X-ray and radio populations. We find the contributions
to the 4-8 keV light from our candidate highly-obscured AGNs to be very small,
and hence these sources are unable to account for the light that has been
suggested may be missing at these energies.


title: Sterile dark matter and reionization

abstract:
  Sterile neutrinos with masses in the keV range can be the dark matter, and
their emission from a supernova can explain the observed velocities of pulsars.
The sterile neutrino decays could produce the x-ray radiation in the early
universe, which could have an important effect on the formation of the first
stars. X-rays could ionize gas and could catalyze the production of molecular
hydrogen during the ``dark ages''. The increased fraction of molecular hydrogen
could facilitate the cooling and collapse of the primordial gas clouds in which
the first stars were formed.


title: Interpretation of the expansion law of planetary nebulae

abstract:
  We reproduce the expansion velocity--radius ($V_{\rm{exp}}$--$R_{\rm{n}}$)
relation in planetary nebulae by considering a simple dynamical model, in order
to investigate the dynamical evolution and formation of planetary nebulae. In
our model, the planetary nebula is formed and evolving by interaction of a fast
wind from the central star with a slow wind from its progenitor, the AGB star.
In particular, taking account of the mass loss history of the AGB star makes us
succeed in the reproduction of the observed $V_{\rm{exp}}$-$R_{\rm{n}}$
sequence. As a result, examining the ensemble of the observational and
theoretical evolution models of PNe, we find that if the AGB star pulsates and
its mass loss rate changes with time (from $\sim 10^{-6.4}M_{\odot}$ yr$^{-1}$
to $\sim 10^{-5}M_{\odot}$ yr$^{-1}$), the model agrees with the observations.
In terms of observation, we suggest that there are few planetary nebulae with
larger expansion velocity and smaller radius because the evolutionary
time-scale of such nebulae is so short and the size of nebulae is so compact
that it is difficult for us to observe them.


title:
The Effect of Orbital Eccentricity on Gravitational Wave Background
  Radiation from Supermassive Black Hole Binaries

abstract:
  A compact binary in an eccentric orbit radiates gravitational waves (GWs) at
all integer harmonics of its orbital frequency. In this study, we investigate
the effect of orbital eccentricity on the expected gravitational background
radiation (GWBR) from supermassive black hole (SMBH) binaries in the nuclei of
galaxies. For this purpose, we formulate a power spectrum of the GWBR from
cosmological evolving eccentric binaries. Then, we apply this formulation to
the case of the GWBR from SMBH binaries. The key to doing this is to correctly
estimate the number density of coalescing SMBH binaries. In this study, we use
a semi-analytic model of galaxy and SMBH formation. We find that the power
spectrum of the GWBR from SMBH binaries on eccentric orbits is suppressed for
frequencies $f \lesssim 1~{\rm nHz}$ if the initial eccentricity, $e_0$,
satisfies $e_0 > 0.2$ and the initial semi-major axis is 300 times Scwarzschild
radius. Our model predicts that while the overall shape and amplitude of the
power spectrum depend strongly on the processes of galaxy formation, the
eccentricity of binaries can affect the shape of the power spectrum for lower
frequencies, i.e., $f \lesssim 1~{\rm nHz}$. Pulsar timing measurements, which
can detect GW in this frequency range, could constrain the effect of
eccentricity on the power spectrum of the GWBR from SMBH binaries.


title: Threshold between Spontaneous and Cloud-Collisional Star Formation

abstract:
  Based on simple physical and geometric assumptions, we have calculated the
mean surface molecular density of spiral galaxies at the threshold between star
formation induced by cloud-cloud collision and spontaneous gravitational
collapse. The calculated threshold is approximately $\log \Sigma_\mathrm{crit}
\sim 2.5$, where $ \Sigma \quad \mathrm{M_{\solar}}\cdot \mathrm{pc}^{-2}$ is
the observed surface mass density of an assumed flat gas disk. Above this
limit, the rate of molecular cloud collisions dominates over spontaneous
molecular cloud collapse. This model may explain the apparent discontinuity in
the Schmidt law found recently at $2 \lesssim \log \Sigma \lesssim 3$.


title: Eclipsing binaries in the open cluster NGC 2243 - I. Photometry

abstract:
  We obtained BV time series photometry for 12 variable stars from the field of
the old open cluster NGC 2243. The sample includes 3 newly identified
detached/semi-detached binaries. There are now four detached eclipsing binaries
which are likely members of the cluster. Determination of the absolute
parameters of the components would provide a valuable check on evolutionary
models of low-mass stars. An accurate ephemeris and orbital period analysis are
presented for the previously-known detached binary NV CMa. We also provide
ephemerides for 7 other periodic variables. We show that 3 contact binaries are
likely members of the cluster.


title:
Eclipsing binaries in the open cluster NGC 2243 - II. Absolute
  properties of NV CMa

abstract:
  We present echelle spectroscopic data for five eclipsing binary stars and two
giant stars in the field of the open cluster NGC 2243. The average cluster
velocity is determined to be +60.4 +- 0.6 km/s. Four of the eclipsing binaries
are very likely members of the cluster based on their observed radial
velocities. The absolute parameters of cluster member NV CMa are determined by
analysing photometric and radial velocity data. We obtain 1.089+-0.010 Msun and
1.221+-0.031 Rsun for the primary, and 1.069+-0.010 Msun and 178+-0.037 Rsun
for the secondary. Both components of the binary are located on the Main
Sequence, about 1 mag. below the turn-off point on the cluster color-magnitude
diagram. Using model age-luminosity and age-radius relations we obtain
4.35+-0.25 Gyr for the age of NV CMa. The derived age is, however, very
sensitive to the adopted metallicity of the cluster. We demonstrate that a
meaningful determination of the ages of objects like NV CMa based on
evolutionary models is possible only if their metallicity is know with a
relative accuracy of a few percent. The distance moduli calculated for the
components of NV CMa agree closely with each other, and imply an apparent
distance modulus of the cluster of (m-M)_V=13.25+-0.08.


title: Dynamical processes in the solar radiative interior

abstract:
  Recent seismic observations coming from acoustic and gravity modes clearly
show that the solar standard model has reached its limits and can no longer be
used to interpret satisfactorily seismic observations. In this paper, we
present a review of the non-standard processes that may be added to the solar
models in order to improve our understanding of the helioseismic data. We also
present some results obtained when applying ``non-standard'' stellar evolution
to the modelling of the Sun.