title:
The search for optical emission on and before the GRB trigger with the
  WIDGET telescope

abstract:
  WIDGET is a robotic telescope for monitoring the HETE-2 field-of-view to
detect Gamma-ray Burst optical flashes or possible optical precursors. The
system has 62degx62deg wide field-of-view which covers about 80% of HETE-2 one
with a 2kx2k Apogee U10 CCD camera and a Canon EF 24mm f/1.4 wide-angle lens
without a bandpass filter. WIDGET has been in operation since June 2004 at
Akeno observing site where is about 200 km apart from Tokyo. Typical limiting
magnitude with S/N=3 at the site is V=10mag for 5 seconds exposure and V=11mag
for 30 seconds exposure. We had already six coincident observations with HETE-2
position alerts. It was, however, cloudy for all cases due to rainy season in
Japan. Expected number of coincident observations under clear sky is about 5
events per year. We will extend the system in early 2005 for Swift era to
monitor optical transients in wider field-of-view, multi-color or polarization
modes.


title: Kiso observations for 20 GRBs in HETE-2 era

abstract:
  We have established a GRB follow-up observation system at Kiso observatory
(Japan) in 2001. Since the east Asian area had been blank for the GRB follow-up
observational network, this observational system is very important in studying
the temporal and spectral evolution of early afterglows. Using this system, we
have performed quick observations for optical afterglows from early phase based
on HETE-2 and INTEGRAL alerts. Thanks to the quick follow-up observation
system, we have been able to use the Kiso observatory in 20 events, and conduct
their follow-up observations in optical and near infrared wavelengths.


title: GRBs Optical follow-up observation at Lulin observatory, Taiwan

abstract:
  The Lulin GRB program, using the Lulin One-meter Telescope (LOT) in Taiwan
started in July 2003. Its scientific aims are to discover optical counterparts
of XRFs and short and long GRBs, then to quickly observe them in multiple
bands. Thirteen follow-up observations were provided by LOT between July 2003
and Feb. 2005. One host galaxy was found at GRB 031203. Two optical afterglows
were detected for GRB 040924 and GRB 041006. In addition, the optical
observations of GRB 031203 and a discussion of the non-detection of the optical
afterglow of GRB 031203 are also reported in this article.


title: BeppoSAX/PDS serendipitous detections at high galactic latitudes

abstract:
  At a flux limit of ~10^(-11) erg/cm2/s in the 20-100 keV band, the PDS
instrument on-board BeppoSAX offers the opportunity to study the extragalactic
sky with an unprecedented sensitivity. In this work we report on the results of
a search in the BeppoSAX archive for serendipitous high energy sources at high
galactic latitudes (|b| > 13 deg). We have defined a set of twelve regions in
which the PDS/MECS cross-calibration constant is higher than the nominal value.
We attribute this mismatch to the presence of a serendipitous source in the PDS
field of view.In four cases the likely high energy emitter is also present in
the MECS field of view. In these cases, we have performed a broad band spectral
analysis (1.5-100 keV) so as to understand the source spectral behaviour and
compare it with previous BeppoSAX observations when available. In eight cases
the identification of the source likely to provide the PDS spectrum is based on
indirect evidence (extrapolation to lower energies and/or comparison to
previous observations). This approach leads to the discovery of six new hard
X-ray emitting objects (PKS 2356-611, 2MASX J14585116-1652223, NGC 1566, NGC
7319, PKS 0101-649 and ESO 025-G002) and to the presentation the PDS spectrum
of NGC 3227 for the first time. In the remaining five cases we provide extra
BeppoSAX observations that can be compared with measurements which are already
published and/or in the archive.


title:
A Comparison of Elemental Abundance Ratios in Globular Clusters, Field
  Stars, and Dwarf Spheroidal Galaxies

abstract:
  We have compiled a sample of globular clusters with high quality stellar
abundances from the literature to compare to the chemistries of stars in the
Galaxy and those in dwarf spheroidal galaxies. Of the 45 globular clusters
examined, 29 also have kinematic information. Most of the globular clusters
belong to the Galactic halo, however a signficant number have disk kinematics
or belong to the bulge. Focusing on the [alpha/Fe] and light r-process element
ratios, we find that most globular cluster stars mimic those of the field stars
of similar metallicities, and neither clearly resembles the presently available
stellar abundances in the dwarf galaxies (including the globular clusters in
the Large Magellanic Cloud). The exceptions to these general elemental ratio
comparisons are already known in the literature, e.g., omega Centauri, Palomar
12, and Terzan 7 associated with the Sagittarius remnant, and Ruprecht 106
which has a high radial velocity and low [alpha/Fe] ratio. A few other globular
clusters show more marginal peculiarities. The most notable one being the halo
cluster M68 which has a high Galactocentric rotational velocity, a slightly
younger age, and a unique [Si/Ti] ratio. The [Si/Ti] ratios decrease with
increasing [Fe/H] at intermediate metallicities, which is consistent with very
massive stars playing a larger role in the early chemical evolution of the
Galaxy. The chemical similarities between globular clusters and field stars
with [Fe/H]<-1.0 suggests a shared chemical history in a well mixed early
Galaxy. The differences to the published chemistries of stars in the dwarf
spheroidal galaxies suggests that neither the globular clusters, halo stars,
nor thick disk stars had their origins in small isolated systems like the
present-day Milky Way dwarf satellites.


title:
Differential rotation and meridional flow in the solar convection zone
  and beneath

abstract:
  The influence of the basic rotation on anisotropic and inhomogeneous
turbulence is discussed in the context of differential rotation theory. An
improved representation for the original turbulence leads to a $\Lam$-effect
which complies with the results of 3D numerical simulations. The resulting
rotation law and meridional flow agree well with both the surface observations
($\partial\Om/\partial r<0$ and meridional flow towards the poles) and with the
findings of helioseismology. The computed equatorward flow at the bottom of
convection zone has an amplitude of about 10 m/s and may be significant for the
solar dynamo. The depth of the meridional flow penetration into the radiative
zone is proportional to $\nu^{0.5}_\mathrm{core}$, where $\nu_\mathrm{core}$ is
the viscosity beneath the convection zone. The penetration is very small if the
tachocline is laminar.


title: High energy gamma-ray emission from the starburst nucleus of NGC 253

abstract:
  The high density medium that characterizes the central regions of starburst
galaxies and its power to accelerate particles up to relativistic energies make
these objects good candidates as $\gamma$-rays sources. In this paper, a
self-consistent model of the multifrequency emission of the starburst galaxy
NGC 253, from radio to gamma-rays, is presented. The model is in agreement with
all current measurements and provides predictions for the high energy behavior
of the NGC 253 central region. Prospects for observations with the HESS array
and GLAST satellite are especially discussed.


title: An XMM-Newton Study of the Coronae of $\sigma^2$ Coronae Borealis

abstract:
  (Abridged) We present results of XMM-Newton observations of the RS CVn binary
$\sigma^2$ Coronae Borealis. The RGS and EPIC MOS2 spectra were simultaneously
fitted with collisional ionization equilibrium plasma models to determine
coronal abundances of various elements. Contrary to the solar first ionization
potential (FIP) effect in which elements with a low FIP are overabundant in the
corona compared to the solar photosphere, and contrary to the ``inverse'' FIP
effect observed in several active RS CVn binaries, coronal abundance ratios in
$\sigma^2$ CrB show a complex pattern as supported by similar findings in the
Chandra HETGS analysis of $\sigma^2$ CrB with a different methodology (Osten et
al. 2003). Low-FIP elements ($<10$ eV) have their abundance ratios relative to
Fe consistent with the solar photospheric ratios, whereas high-FIP elements
have their abundance ratios increase with increasing FIP. We find that the
coronal Fe abundance is consistent with the stellar photospheric value,
indicating that there is no metal depletion in $\sigma^2$ CrB. However, we
obtain a higher Fe absolute abundance than in Osten et al. (2003). Except for
Ar and S, our absolute abundances are about 1.5 times larger than those
reported by Osten et al. (2003). However, a comparison of their model with our
XMM-Newton data (and vice versa) shows that both models work adequately in
general. We find, therefore, no preference for one methodology over the other
to derive coronal abundances. Despite the systematic discrepancy in absolute
abundances, our abundance ratios are very close to those obtained by Osten et
al. (2003). Finally, we confirm the measurement of a low density in \ion{O}{7}
($< 4 \times 10^{10}$ cm$^{-3}$), but could not confirm the higher densities
measured in spectral lines formed at higher temperatures.


title:
The Sgr B2 X-ray Echo of the Galactic Center Supernova Explosion that
  Produced Sgr A East

abstract:
  The possible impact Sgr A East is having on the Galactic center has fueled
speculation concerning its age and the energetics of the supernova explosion
that produced it. We have carried out the first in-depth analysis of the
remnant's evolution and its various interactions: with the stellar winds
flowing out from the inner ~2 pc, with the supermassive black hole, Sgr A*, and
with the 50 km/s molecular cloud behind and to the East of the nucleus. We have
found that a rather "standard" supernova explosion with energy ~1.5e51 ergs is
sufficient to create the remnant we see today, and that the latter is probably
only ~1,700 years old. The X-ray Ridge between ~9" and 15" to the NE of Sgr A*
appears to be the product of the current interaction between the remaining
supernova ejecta and the outflowing winds. Perhaps surprisingly, we have also
found that the passage of the remnant across the black hole would have enhanced
the accretion rate onto the central object by less than a factor 2. Such a
small increase cannot explain the current Fe fluorescence observed from the
molecular cloud Sgr B2; this fluorescence would have required an increase in
Sgr A*'s luminosity by 6 orders of magnitude several hundred years ago.
Instead, we have uncovered what appears to be a more plausible scenario for
this transient irradiation--the interaction between the expanding remnant and
the 50 km/s molecular cloud. The first impact would have occurred about 1,200
years after the explosion, producing a 2-200 keV luminosity of ~1e39 ergs/s.
During the intervening 300-400 years, the dissipation of kinetic energy
subsided considerably, leading to the much lower luminosity (~1e36 ergs/s at
2-10 keV) we see today.


title: Concurrent 43 and 86 GHz Very Long Baseline Polarimetry of 3C273

abstract:
  We present sub-milliarcsecond resolution total intensity and linear
polarization VLBI images of 3C273, using concurrent 43 and 86 GHz data taken
with the Very Long Baseline Array in May 2002. The structure seen in the
innermost jet suggest that we have fortuitously caught the jet in the act of
changing direction. The polarization images confirm that the core is
unpolarized (fractional polarization m < 1 %) at 86 GHz, but also show well
ordered magnetic fields (m ~ 15 %) in the inner jet, at a projected distance of
2.3 pc from the core. In this strongly polarized region, the rotation measure
changes across the jet by 4.2 x 10^{4} rad m^{-2} over an angular width of
about 0.3 milliarcseconds. If the lack of polarization in the core is also
attributed to a Faraday screen, then a rotation measure dispersion > 5.2 x
10^{4} rad m^{-2} must be present in or in front of that region. These are
among the highest rotation measures reported so far in the nucleus of any
active galaxy or quasar, and must occur outside (but probably close to) the
radio emitting region. The transverse rotation measure gradient is in the same
sense as that observed by Asada et al and by Zavala and Taylor at greater core
distances. The magnitude of the transverse gradient decreases rapidly with
distance down the jet, and appears to be variable.


title: The X-ray Ridge Surrounding Sgr A* at the Galactic Center

abstract:
  We present the first detailed simulation of the interaction between the
supernova explosion that produced Sgr A East and the wind-swept inner ~ 2-pc
region at the Galactic center. The passage of the supernova ejecta through this
medium produces an X-ray ridge ~ 9'' to 15'' to the NE of the supermassive
black hole Sagittarius A* (Sgr A*). We show that the morphology and X-ray
intensity of this feature match very well with recently obtained Chandra
images, and we infer a supernova remnant age of less than 2,000 years. This
young age--a factor 3--4 lower than previous estimates--arises from our
inclusion of stellar wind effects in the initial (pre-explosion) conditions in
the medium. The supernova does not clear out the central ~ 0.2-pc region around
Sgr~A* and does not significantly alter the accretion rate onto the central
black hole upon passage through the Galactic center.


title:
Extremely Luminous Water Vapor Emission from a Type 2 Quasar at Redshift
  z = 0.66

abstract:
  A search for water masers in 47 Sloan Digital Sky Survey Type 2 quasars using
the Green Bank Telescope has yielded a detection at a redshift of z = 0.660.
This maser is more than an order of magnitude higher in redshift than any
previously known and, with a total isotropic luminosity of 23,000 L_sun, also
the most powerful. The presence and detectability of water masers in quasars at
z ~ 0.3-0.8 may provide a better understanding of quasar molecular tori and
disks, as well as fundamental quasar and galaxy properties such as black hole
masses. Water masers at cosmologically interesting distances may also
eventually provide, via direct distance determinations, a new cosmological
observable for testing the reality and properties of dark energy, currently
inferred primarily through Type 1a supernova measurements.


title:
Toward a unified light curve model for multi-wavelength observations of
  V1974 Cygni (Nova Cygni 1992)

abstract:
  We present a unified model for optical, ultraviolet (UV), and X-ray light
curves of V1974 Cygni (Nova Cygni 1992). Based on an optically thick wind model
of nova outbursts, we have calculated light curves and searched for the best
fit model that is consistent with optical, UV, and X-ray observations. Our best
fit model is a white dwarf (WD) of mass 1.05 M_\sun with a chemical composition
of X=0.46, C+N+O=0.15, and Ne = 0.05 by mass weight. Both supersoft X-ray and
continuum UV 1455 \AA light curves are well reproduced. Supersoft X-rays
emerged on day ~ 250 after outburst, which is naturally explained by our model:
our optically thick winds cease on day 245 and supersoft X-rays emerge from
self-absorption by the winds. The X-ray flux keeps a constant peak value for ~
300 days followed by a quick decay on day ~ 600. The duration of X-ray flat
peak is well reproduced by a steady hydrogen shell burning on the WD. Optical
light curve is also explained by the same model if we introduce free-free
emission from optically thin ejecta. A t^{-1.5} slope of the observed optical
and infrared fluxes is very close to the slope of our modeled free-free light
curve during the optically thick wind phase. Once the wind stops, optical and
infrared fluxes should follow a t^{-3} slope, derived from a constant mass of
expanding ejecta. An abrupt transition from a t^{-1.5} slope to a t^{-3} slope
at day ~ 200 is naturally explained by the change from the wind phase to the
post-wind phase on day ~ 200. The development of hard X-ray flux is also
reasonably understood as shock-origin between the wind and the companion star.
The distance to V1974 Cyg is estimated to be ~ 1.7 kpc with E(B-V)= 0.32 from
the light curve fitting for the continuum UV 1455 \AA.


title: Discovery of pulsations in the X-ray transient 4U 1901+03

abstract:
  We describe observations of the 2003 outburst of the hard-spectrum X-ray
transient 4U 1901+03 with the Rossi X-ray Timing Explorer. The outburst was
first detected in 2003 February by the All-Sky Monitor, and reached a peak
2.5-25 keV flux of 8x10^-9 ergs/cm^2/s (around 240 mCrab). The only other known
outburst occurred 32.2 yr earlier, likely the longest presently known
recurrence time for any X-ray transient. Proportional Counter Array (PCA)
observations over the 5-month duration of the 2003 outburst revealed a 2.763 s
pulsar in a 22.58 d orbit. The detection of pulsations down to a flux of
3x10^-11 ergs/cm^2/s (2.5-25 keV), along with the inferred long-term accretion
rate of 8.1x10^-11 M_sun/yr (assuming a distance of 10 kpc) suggests that the
surface magnetic field strength is below ~5x10^11 G. The corresponding
cyclotron energy is thus below 4 keV, consistent with the non-detection of
resonance features at high energies. Although we could not unambiguously
identify the optical counterpart, the lack of a bright IR candidate within the
1' RXTE error circle rules out a supergiant mass donor. The neutron star in 4U
1901+03 probably accretes from the wind of a main-sequence O-B star, like most
other high-mass binary X-ray pulsars. The almost circular orbit e=0.036
confirms the system's membership in a growing class of wide, low-eccentricity
systems in which the neutron stars may have received much smaller kicks as a
result of their natal supernova explosions.


title: Lectures on High-Energy Neutrino Astronomy

abstract:
  Kilometer-scale neutrino detectors such as IceCube are discovery instruments
covering nuclear and partile physics, cosmology and astronomy. Examples of
their multidisciplinary mission include the search for the particle nature of
dark matter and for additional small dimensions of space. In these lectures, we
discuss the nature of cosmic neutrinos and their sources, the need for
kilometer-scale detectors and the status and methodologies of current
detectors.


title:
Statistical Analysis of Galaxy Surveys-II. The 3-point galaxy
  correlation function measured from the 2dFGRS

abstract:
  We present new results for the 3-point correlation function, \zeta, measured
as a function of scale, luminosity and colour from the final version of the
two-degree field galaxy redshift survey (2dFGRS). The reduced three point
correlation function, Q_3 is estimated for different triangle shapes and sizes,
employing a full covariance analysis. The form of Q_3 is consistent with the
expectations for the \Lambda-cold dark matter model, confirming that the
primary influence shaping the distribution of galaxies is gravitational
instability acting on Gaussian primordial fluctuations. However, we find a
clear offset in amplitude between Q_3 for galaxies and the predictions for the
dark matter. We are able to rule out the scenario in which galaxies are
unbiased tracers of the mass at the 9-sigma level. On weakly non-linear scales,
we can interpret our results in terms of galaxy bias parameters. We find a
linear bias term that is consistent with unity, b_1 = 0.93^{+0.10}_{-0.08} and
a quadratic bias c_2 = b_2 /b_1 = -0.34^{+0.11}_{-0.08}. This is the first
significant detection of a non-zero quadratic bias, indicating a small but
important non-gravitational contribution to the three point function. Our
estimate of the linear bias from the three point function is independent of the
normalisation of underlying density fluctuations, so we can combine this with
the measurement of the power spectrum of 2dFGRS galaxies to constrain the
amplitude of matter fluctuations. We find that the rms linear theory variance
in spheres of radius 8Mpc/h is \sigma_8 = 0.88^{+0.12}_{-0.10}, providing an
independent confirmation of values derived from other techniques. On non-linear
scales, where \xi>1, we find that Q_3 has a strong dependence on scale, colour
and luminosity.


title: Infrared Observations of Neutron-Capture Elements in Planetary Nebulae

abstract:
  We present results from an ongoing survey of the infrared emission lines [Kr
III] 2.199 and [Se IV] 2.287 micron in Galactic planetary nebulae (PNe).
Krypton and selenium may be produced by slow neutron-capture nucleosynthesis
(the ``s-process'') during the asymptotic giant branch (AGB) phase of PN
progenitor stars, and brought to the surface by convective dredge-up before PN
ejection. We detect emission from Se and Kr in 65 of 114 Galactic PNe, and use
the line fluxes to derive ionic abundances. We employ ionization correction
factors based on coincidences of ionization potentials to calculate total
elemental abundances, and discuss photoionization models designed to test the
veracity of these corrections. The derived Se and Kr abundances of our targets
range from approximately solar to enriched by a factor of 5, which indicates
varying degrees of dredge-up and s-process efficiencies in the progenitor
stars. In PNe exhibiting emission from both Se and Kr, we find that the
relative abundances of these elements are generally in agreement with
predictions from theoretical models of s-process nucleosynthesis. We examine
our results for correlations between s-process enrichments and other nebular
properties, such as CNO abundances, morphology, and characteristics of the
central stars. PNe with Wolf-Rayet central stars tend to exhibit more elevated
Se and Kr abundances than other nebulae. Bipolar nebulae, believed to arise
from the most massive of PN progenitors, may have lower n-capture abundances
than elliptical PNe.


title:
Optical Spectroscopy of the Surface Population of the rho Ophiuchi
  Molecular Cloud: The First Wave of Star Formation

abstract:
  We present the results of optical spectroscopy of 139 stars obtained with the
Hydra multi-object spectrograph. The objects extend over a 1.3 square degree
area surrounding the main cloud of the rho Oph complex. The objects were
selected from narrowband images to have H alpha in emission. Using the presence
of strong H alpha emission, lithium absorption, location in the
Hertzsprung-Russell diagram, or previously reported x-ray emission, we were
able to identify 88 objects as young stars associated with the cloud. Strong H
alpha emission was confirmed in 39 objects with line widths consistent with
their origin in magnetospheric accretion columns. Two of the strongest
emission-line objects are young, x-ray emitting brown dwarf candidates with M8
spectral types. Comparisons of the bolometric luminosities and effective
temperatures with theoretical models suggest a medianage for this population of
2.1 Myr which is signifcantly older than the ages derived for objects in the
cloud core. It appears that these stars formed contemporaneously with low mass
stars in the Upper Scorpius subgroup, likely triggered by massive stars in the
Upper-Centaurus subgroup.


title:
Formation and Evolution of Planetary Systems: Upper Limits the Gas Mass
  in HD105

abstract:
  We report infrared spectroscopic observations of HD 105, a nearby ($\sim 40$
pc) and relatively young ($\sim 30$ Myr) G0 star with excess infrared continuum
emission, which has been modeled as arising from an optically thin
circumstellar dust disk with an inner hole of size $\gtrsim 13$ AU. We have
used the high spectral resolution mode of the Infrared Spectrometer (IRS) on
the Spitzer Space Telescope to search for gas emission lines from the disk. The
observations reported here provide upper limits to the fluxes of H$_2$ S(0)
28$\mu$m, H$_2$ S(1) 17$\mu$m, H$_2$ S(2) 12 $\mu$m, [FeII] 26$\mu$m, [SiII]
35$\mu$m, and [SI] 25$\mu$m infrared emission lines. The H$_2$ line upper
limits directly place constraints on the mass of warm molecular gas in the
disk: $M({\rm H_2})< 4.6$, 3.8$\times 10^{-2}$, and $3.0\times 10^{-3}$ M$_J$
at $T= 50$, 100, and 200 K, respectively. We also compare the line flux upper
limits to predictions from detailed thermal/chemical models of various gas
distributions in the disk. These comparisons indicate that if the gas
distribution has an inner hole with radius $r_{i,gas}$, the surface density at
that inner radius is limited to values ranging from $\lesssim 3$ gm cm$^{-2}$
at $r_{i,gas}=0.5$ AU to 0.1 gm cm$^{-2}$ at $r_{i,gas}= 5-20$ AU. These values
are considerably below the value for a minimum mass solar nebula, and suggest
that less than 1 M$_J$ of gas (at any temperature) exists in the 1-40 AU
planet-forming region. Therefore, it is unlikely that there is sufficient gas
for gas giant planet formation to occur in HD 105 at this time.


title: How JWST can measure First Light, Reionization and Galaxy Assembly

abstract:
  We summarize the design and performance of the James Webb Space Telescope
that is to be launched to an L2 orbit in 2011, and how it is designed, in
particular, to study the epochs of First Light, Reionization and Galaxy
Assembly.


title: Deuterated H$_3^+$ in proto-planetary disks

abstract:
  Probing the gas and dust in proto-planetary disks is central for
understanding the process of planet formation. In disks surrounding solar type
protostars, the bulk of the disk mass resides in the outer midplane, which is
cold ($\leq$20 K), dense ($\geq 10^7$ cm$^{-3}$) and depleted of CO. Observing
the disk midplane has proved, therefore, to be a formidable challenge.
Ceccarelli et al. (2004) detected H$_2$D$^+$ emission in a proto-planetary disk
and claimed that it probes the midplane gas. Indeed, since all heavy-elements
bearing molecules condense out onto the grain mantles, the most abundant ions
in the disk midplane are predicted to be H$_3^+$ and its isotopomers. In this
article, we carry out a theoretical study of the chemical structure of the
outer midplane of proto-planetary disks. Using a self-consistent physical model
for the flaring disk structure, we compute the abundances of H$_3^+$ and its
deuterated forms across the disk midplane. We also provide the average column
densities across the disk of H$_3^+$, H$_2$D$^+$, HD$_2^+$ and D$_3^+$, and
line intensities of the ground transitions of the ortho and para forms of
H$_2$D$^+$ and HD$_2^+$ respectively. We discuss how the results depend on the
cosmic ray ionization rate, dust-to-gas ratio and average grain radius, and
general stellar/disk parameters. An important factor is the poorly understood
freeze-out of N$_2$ molecules onto grains, which we investigate in depth. We
finally summarize the diagnostic values of observations of the H$_3^+$
isotopomers.


title: Cosmological Constraints on a Power Law Universe

abstract:
  Linearly coasting cosmology is comfortably concordant with a host of
cosmological observations. It is surprisingly an excellent fit to SNe Ia
observations and constraints arising from age of old quasars. In this article
we highlight the overall viability of an open linear coasting cosmological
model.The model is consistent with the latest SNe Ia ``gold'' sample and
accommodates a very old high-redshift quasar, which the standard cold-dark
model fails to do.


title: Quark stars and quantum-magnetically induced collapse

abstract:
  Quark matter is expected to exist in the interior of compact stellar objects
as neutron stars or even the more exotic strange stars, based on the
Bodmer-Witten conjecture. Bare strange quark stars and (normal) strange
quark-matter stars, those possessing a baryon (electron-supported) crust, are
hypothesized as good candidates to explain the properties of a set of peculiar
stellar sources as the enigmatic X-ray source RX J1856.5-3754, some pulsars as
PSR B1828-11 and PSR B1642-03, and the anomalous X-ray pulsars and soft
gamma-ray repeaters. In the MIT bag model, quarks are treated as a degenerate
Fermi gas confined to a region of space having a vacuum energy density
$B_{bag}$ (the Bag constant). In this note, we modif{}y the MIT Bag Model by
including the electromagnetic interaction. We also show that this version of
the MIT model implies the anisotropy of the Bag pressure due to the presence of
the magnetic field. The equations of state of degenerate quarks gases are
studied in the presence of ultra strong magnetic fields. The behavior of a
system made-up of quarks having (or not) anomalous magnetic moment is reviewed.
A structural instability is found, which is related to the anisotropic nature
of the pressures in this highly magnetized matter. The conditions for the
collapse of this system are obtained and compared to a previous model of
neutron stars build-up on a neutron gas having anomalous magnetic moment.


title:
Spectroscopic classification of red high proper motion objects in the
  Southern Sky

abstract:
  We present the results of spectroscopic follow-up observations for a sample
of 71 red objects with high proper motions in the range 0.08-1.14 arcsec/yr as
detected using APM and SSS measurements of multi-epoch photographic Schmidt
plates. Red objects were selected by combining the photographic BjRI magnitudes
with 2MASS near-infrared JHKs magnitudes. Some 50 of the 71 spectroscopically
classified objects turn out to be late-type (>M6) dwarfs and in more detail,
the sample includes 35 ultracool dwarfs with spectral types between M8 and L2,
some previously reported, as well as five M-type subdwarfs, including a cool
esdM6 object, SSSPM J0500-5406. Distance estimates based on the spectral types
and 2MASS J magnitudes place almost all of the late-type (>M6) dwarfs within 50
pc, with 25 objects located inside the 25 pc limit of the catalogue of nearby
stars. Most of the early-type M dwarfs are located at larger distances of
100-200 pc, suggesting halo kinematics for some of them. All objects with
Halpha equivalent widths larger than 10 Angstroms have relatively small
tangential velocities (<50 km/s). Finally, some late-type but blue objects are
candidate binaries.


title:
Chandra Study of X-Ray Point Sources in the Early-Type Galaxy NGC 4552
  (M89)

abstract:
  We present a Chandra ACIS study of the early-type galaxy NGC 4552. We detect
47 X-ray point sources, most of which are likely LMXBs, within 4 R_e. The
brightest X-ray source coincides with the optical/UV/radio center of the
galaxy, and shows variability on >1 hr timescales, indicating the possible
existence of a LLAGN. The 46 off-center sources and the unresolved point
sources contribute about 29% and 20% to the total luminosity of the galaxy,
respectively. The corrected cumulative XLF of the off-center sources is best
fit by a broken power-law model with a break at L_b=4.4+2.0-1.4 e38 ergs/s. We
identified 210 GCs candidates in a HST WFPC2 optical image of the galaxy's
central region. Of the 25 off-center LMXBs that fall within the WFPC2 FOV, 10
sources are coincident with a GC. Thus the fraction of the GCs hosting bright
LMXBs and the fraction of the LMXBs associated with GCs are 4.8% and 40%,
respectively. In the V and I bands, the GCs hosting bright LMXBs are typically
1-2 magnitudes brighter than the GCs with no detected LMXBs. There are about
1.9+-0.4 times as many LMXBs in the red, metal-rich GCs as there are in the
blue, metal-poor ones. We find no obvious difference between the luminosity
distributions of LMXBs in GCs and in field, but the cumulative spectrum of the
LMXBs in GCs tends to be softer than that of the LMXBs in field. We detected 3
X-ray sources that have isotropic luminosities larger than 1e39 erg/s. The one
located in the joint Chandra-HST field is found to be associated with a GC. By
studying the ACIS spectra we infer that the this may be a candidate black hole
system with a mass of 15-135 M_sun. One of the other sources with a luminosity
brighter than 1e39 ergs/s reveals temporal variations in brightness on
timescales greater than an hour.


title: Early re-brightening of the afterglow of GRB 050525a

abstract:
  We present time resolved optical data acquired by the TAROT automated
observatory on the afterglow of GRB 050525a from 6 to 136 minutes after the
GRB. We evidence a rapid re-brightening of 0.65 magnitude of the afterglow at
$\sim$ 33 min after the GRB. The decay slope $\alpha$ is $1.14\pm 0.07$ in the
first part and is $1.23\pm 0.27$ after the re-brightening event. The afterglow
of GRB 050525a is the third known afterglow that exhibits a re-brightening
event begining at 0.01--0.02 day in the rest time frame.


title:
Chandra Observation of the Cluster of Galaxies MS 0839.9+2938 at
  z=0.194: the Central Excess Iron and SN Ia Enrichment

abstract:
  We present the Chandra study of the intermediately distant cluster of
galaxies MS 0839.9+2938. By performing both the projected and deprojected
spectral analyses, we find that the gas temperature is approximately constant
at about 4 keV in 130-444h_70^-1 kpc. In the inner regions, the gas temperature
descends towards the center, reaching <~ 3 keV in the central 37h_70^-1 kpc.
This infers that the lower and upper limits of the mass deposit rate are 9-34
M_sun yr^-1 and 96-126 M_sun yr^-1, respectively within 74h_70^-1 kpc where the
gas is significantly colder. Along with the temperature drop, we detect a
significant inward iron abundance increase from about 0.4 solar in the outer
regions to about 1 solar within the central 37h_70^-1 kpc. Thus MS 0839.9+2938
is the cluster showing the most significant central iron excess at z>~ 0.2. We
argue that most of the excess iron should have been contributed by SNe Ia. By
utilizing the observed SN Ia rate and stellar mass loss rate, we estimate that
the time needed to enrich the central region with excess iron is 6.4-7.9 Gyr,
which is similar to those found for the nearby clusters. Coinciding with the
optical extension of the cD galaxy (up to about 30h_70^-1 kpc), the observed
X-ray surface brightness profile exhibits an excess beyond the distribution
expected by either the beta model or the NFW model, and can be well fitted with
an empirical two-beta model that leads to a relatively flatter mass profile in
the innermost region.


title:
Laboratory simulation of cometary x rays using a high-resolution
  microcalorimeter

abstract:
  X-ray emission following charge exchange has been studied on the University
of California Lawrence Livermore National Laboratory electron beam ion traps
EBIT-I and EBIT-II using a high-resolution microcalorimeter. The measured
spectra include the K-shell emission from hydrogenlike and heliumlike C, N, O,
and Ne needed for simulations of cometary x-ray emission. A comparison of the
spectra produced in the interaction of O8+ with N2 and CH4 is presented that
illustrates the dependence of the observed spectrum on the interaction gas.


title: A New delta N Formalism for Multi-Component Inflation

abstract:
  The delta N formula that relates the final curvature perturbation on comoving
slices to the inflaton perturbation on flat slices after horizon crossing is a
powerful and intuitive tool to compute the curvature perturbation spectrum from
inflation. However, it is customarily assumed further that the conventional
slow-roll condition is satisfied, and satisfied by all components, during
horizon crossing. In this paper, we develop a new delta N formalism for
multi-component inflation that can be applied in the most general situations.
This allows us to generalize the idea of general slow-roll inflation to the
multi-component case, in particular only applying the general slow-roll
condition to the relevant component. We compute the power spectrum of the
curvature perturbation in multi-component general slow-roll inflation, and find
that under quite general conditions it is invertible.


title: Ultracool dwarfs

abstract:
  We present results of modeling of spectra of M-, L-, T-dwarfs. Theoretical
spectra are fitted to observed spectra to study the main parameters of the
low-mass objects beyond the bottom of Main Sequence. Application of ``lithium''
and ``deuterium'' tests for assessment of ultra-cool dwarfs are discussed.


title: Frequency dependence of the drifting subpulses of PSR B0031-07

abstract:
  The well known drifter PSR B0031-07 is known to exhibit drifting subpulses
where the spacing between the drift bands (P_3) shows three distinct modes A, B
and C corresponding to 12, 6 and 4 seconds respectively. We have investigated
periodicities and polarisation properties of PSR B0031-07 for a sequence of
2700 single pulses taken simultaneously at 328 MHz and 4.85 GHz. We found that
mode A occurs simultaneously at these frequencies, while modes B and C only
occur at 328 MHz. However, when the pulsar is emitting in mode B at the lower
frequency there is still emission at the higher frequency, hinting towards the
presence of mode B emission at a weaker level. Further, we have established
that modes A and B are associated with two orthogonal modes of polarisation,
respectively. Based on these observations, we suggest a geometrical model where
modes A and B at a given frequency are emitted in two concentric rings around
the magnetic axis with mode B being nested inside mode A. Further, it is
evident that this nested configuration is preserved across frequency with the
higher frequency arising closer to the stellar surface compared to the lower
one, consistent with the well known radius-to-frequency mapping operating in
pulsars.


title: Secular Evolution of Galaxies

abstract:
  In current $\Lambda$CDM galaxy formation scenarios, at least three physical
phenomena could contribute to the mass assembly: monolithic collapse,
hierarchical mergers and more quiescent external gas accretion, with secular
evolution. The three processes are described, and their successes and problems
are reviewed. It is shown that monolithic collapse is likely to be quite
restricted to sub-components of galaxies, while the two main scenarii,
hierarchical merging and secular evolution, might have comparable roles,
depending on environment. Evidences are reviewed for the important role of gas
accretion, followed by secular evolution. In particular the existence of thin
and cold disks, the occurence of bars and spiral structure, the frequency of
lopsided instabilities, and the history of star formation, all point towards
large amounts of cold gas accretion. Some examples of N-body simulations are
reviewed in support of secular evolution.


title:
The double-mode nature of the HADS star GSC 00144-03031 and the Petersen
  diagram of the class

abstract:
  The double--mode pulsation of GSC 00144-03031 has been detected when
searching for COROT targets. A very large dataset composed of 4722 photometric
measurements was collected at six observatories in Europe and America. There is
no hint of the excitation of additional modes (down to 0.6 mmag) and therefore
GSC 00144-03031 seems to be a pure double--mode pulsator, with a very short
fundamental radial mode (P=84 min). From Stromgren photometry and evolutionary
tracks it appears to be a Pop. I star with M=1.75 solar masses, located in the
middle of the instability strip, close to the Zero--Age Main Sequence. We also
discovered other new double--mode pulsators in the databases of large--scale
projects: OGLE BW2_V142, OGLE BW1_V207, ASAS3 094303-1707.3, ASAS3
000116-6037.0, NSVS 3234596 and NSVS 3324715. An observational Petersen diagram
is presented and explained by means of new models. A common sequence connecting
Pop. I stars from the shortest to the longest periods is proposed and the
spreads in the period ratios are ascribed to different metallicities (at the
shortest periods) and to different masses (at the longest ones). The paper is
based on data collected at S. Pedro Martir and Sierra Nevada Observatories and
on the contributions from several amateur astronomers.


title: Photometric observations from theoretical flip-flop models

abstract:
  Some active stars show a so-called flip-flop phenomenon in which the main
spot activity periodically switches between two active longitudes that are 180
degrees apart. In this paper we study the flip-flop phenomenon by converting
results from dynamo calculations into long-term synthetic photometric
observations, which are then compared to the real stellar observations. We show
that similar activity patterns as obtained from flip-flop dynamo calculations,
can also be seen in the observations. The long-term light-curve behaviour seen
in the synthesised data can be used for finding new stars exhibiting the
flip-flop phenomenon.


title: A sample of radio-loud AGN in the Sloan Digital Sky Survey

abstract:
  A sample of 2712 radio-luminous galaxies is defined from the second data
release of the Sloan Digital Sky Survey (SDSS) by cross-comparing the main
spectroscopic galaxy sample with two radio surveys: the NRAO VLA Sky Survey
(NVSS) and the Faint Images of the Radio Sky at Twenty centimetres (FIRST)
survey. The comparison is carried out in a multi-stage process and makes
optimal use of both radio surveys by exploiting the sensitivity of the NVSS to
extended and multi-component radio sources in addition to the high angular
resolution of the FIRST images. A radio source sample with 95% completeness and
98.9% reliability is achieved, far better than would be possible for this
sample if only one of the surveys was used. The radio source sample is then
divided into two classes: radio-loud AGN and galaxies in which the radio
emission is dominated by star formation. The division is based on the location
of a galaxy in the plane of 4000Ang break strength versus radio luminosity per
unit stellar mass and provides a sample of 2215 radio-loud AGN and 497 star
forming galaxies brighter than 5mJy at 1.4GHz. A full catalogue of positions
and radio properties is provided for these sources. The local radio luminosity
function is then derived both for radio-loud AGN and for star-forming galaxies
and is found to be in agreement with previous studies. By using the radio to
far-IR correlation, the radio luminosity function of star forming galaxies is
also compared to the luminosity function derived in the far-infrared. It is
found to agree well at high luminosities but less so at lower luminosities,
confirming that the linearity of the radio to far-IR correlation breaks down
below about 10^22 W/Hz at 1.4GHz.


title:
The host galaxies of radio-loud AGN: mass dependencies, gas cooling and
  AGN feedback

abstract:
  The properties of the host galaxies of a well-defined sample of 2215
radio-loud AGN with redshifts 0.03 < z < 0.3, defined from the SDSS, are
investigated. These are predominantly low radio luminosity sources, with 1.4GHz
luminosities of 10^23 to 10^25 W/Hz. The fraction of galaxies that host
radio-loud AGN with L(1.4GHz) > 10^23 W/Hz is a strong function of stellar
mass, rising from nearly zero below a stellar mass of 10^10 Msun to more than
30% at 5x10^11 Msun. The integral radio luminosity function is derived in six
ranges of stellar and black hole mass. Its shape is very similar in all of
these ranges and can be well fitted by a broken power-law. Its normalisation
varies strongly with mass, as M_*^2.5 or M_BH^1.6; this scaling only begins to
break down when the predicted radio-loud fraction exceeds 20-30%. There is no
correlation between radio and emission line luminosities for the radio-loud AGN
in the sample and the probability that a galaxy of given mass is radio-loud is
independent of whether it is optically classified as an AGN. The host galaxies
of the radio-loud AGN have properties similar to those of ordinary galaxies of
the same mass.
  All of these findings support the conclusion that the optical AGN and low
radio luminosity AGN phenomena are independent and are triggered by different
physical mechanisms. Intriguingly, the dependence on black hole mass of the
radio-loud AGN fraction mirrors that of the rate at which gas cools from the
hot atmospheres of elliptical galaxies. It is speculated that gas cooling
provides a natural explanation for the origin of the radio-loud AGN activity,
and it is argued that AGN heating could plausibly balance the cooling of the
gas over time. [Abridged]


title: Three-dimensional stability of the solar tachocline

abstract:
  The three-dimensional, hydrodynamic stability of the solar tachocline is
investigated based on a rotation profile as a function of both latitude and
radius. By varying the amplitude of the latitudinal differential rotation, we
find linear stability limits at various Reynolds numbers by numerical
computations. We repeated the computations with different latitudinal and
radial dependences of the angular velocity. The stability limits are all higher
than those previously found from two-dimensional approximations and higher than
the shear expected in the Sun. It is concluded that any part of the tachocline
which is radiative is hydrodynamically stable against small perturbations.


title:
On the origin of the X-ray emission towards the early Herbig Be star MWC
  297

abstract:
  We present high resolution AO-corrected coronographic near-infrared imaging
on the early-type Herbig Be star MWC 297. X-ray flaring has been reported
towards this young object, however this has been difficult to reconcile with
its early spectral type (B1.5) and relatively high mass (10 Msun). Our infrared
and X-ray analysis shows that the X-ray flaring is likely due to a late-type
star in the same field. The case of MWC 297 emphasizes the need for
coronographic imaging to address the reality of X-ray emission towards Herbig
Ae/Be stars, which is needed to understand the differences between low and
high-mass star formation.


title: Brief history of the metal accumulation in the intracluster medium

abstract:
  We use models of the rates of Type Ia supernovae (SNe Ia) and core-collapse
supernovae, built in such a way that both are consistent with recent
observational constraints at z<1.6 and can reproduce the measured cosmic star
formation rate, to recover the history of the metals accumulation in the
intra-cluster medium. We show that these SN rates, in unit of SN number per
comoving volume and rest-frame year, provide on average a total amount of Iron
that is marginally consistent with the value measured in galaxy clusters in the
redshift range 0-1, and a relative evolution with redshift that is in agreement
with the observational constraints up to z~1.2. Moreover, we verify that the
predicted metals to Iron ratios reproduce the measurements obtained in nearby
clusters through X-ray analysis, implying that (1) about half of the Iron mass
and >75 per cent of the Nickel mass observed locally are produced by SN Ia
ejecta, (2) the SN Ia contribution to the metal budget decreases steeply with
redshift and by z~1 is already less than half of the local amount and (3) a
transition in the abundance ratios relative to the Iron is present between
redshifts ~0.5 and 1.4, with core-collapse SN products becoming dominant at
higher redshifts.


title: Properties of FIRBACK-ELAIS 175 um sources in the ELAIS N2 region

abstract:
  We report on a search for the optical counterparts of 175 um - selected
sources from the Far-Infrared Background (FIRBACK) survey in the European Large
Area ISO Survey (ELAIS) N2 field. Applying a likelihood ratio technique to
optical catalogues from the Isaac Newton Telescope - Wide Field Survey
(INT--WFS), we found optical identifications for 33 out of 55 FIRBACK sources
in this field. These were then reassessed in the light of associations with the
ELAIS final catalogue for the the N2 field, to yield a final set of 31
associations. We have investigated the nature of this population through a
comparison of their observed spectral energy distributions with predictions
from radiative transfer models which simulate the emission from both cirrus and
starburst components. We find the far-infrared sources to be 80 per cent star
bursting galaxies with their starburst component at a high optical depth. The
resulting SEDs were used to estimate far-infrared luminosities, star formation
rates, dust temperatures and dust masses. The N2 FIRBACK population is found to
consist of four suspected ULIRGs, a number of LIRGs and a population of low
redshift quiescently star forming galaxies. We also discuss the implications of
these results for current evolutionary models.


title:
HST/STIS Spectroscopy of the Lyman-Alpha Emission Line in the Central
  Dominant Galaxies in A426, A1795, and A2597: Constraints on Clouds in the
  Intracluster Medium

abstract:
  We report on HST/STIS spectra of the Lyman-alpha emission in the central
dominant galaxies in three rich clusters of galaxies. We find evidence for a
population of clouds in the intracluster medium.We detect 10 Ly-alpha
absorption systems towards the nucleus of NGC1275 with columns of N(HI)
1E12-1E14 cm-2. The detected absorption features are most consistent with
associated nuclear absorption systems. There is very little nuclear absorption
at the systemic velocity in NGC1275. This implies that the large columns
detected in the 21 cm line towards the parsec scale radio source avoid the line
of sight to the nucleus. This gas may be located in a circumnuclear disk or
torus. We detect at least one and possibly two absorption features towards the
extended Ly-alpha in A426. We do not detect absorption towards the extended
Ly-alpha emission in A1795, and A2597 with upper limits N(HI) 1E13 cm-2 for
optically thin absorbers. Our data constrain the covering factor of any high
column density gas in the ICM to be less than 25%. Our results suggest that the
lack of observed intermediate temperature gas is not explained by obscuration.
In addition, the low columns of gas on the 100 kpc scales in the ICM suggests
that (1) the rate at which cold gas accumulates in the ICM on these scales is
very low, and (2) the dense nebulae in the central 10 kpc must have cooled or
been deposited in situ.


title: The Discovery of Spiral Arms in the Starburst Galaxy M82

abstract:
  We report the discovery of two symmetric spiral arms in the near-infrared
(NIR) images of the starburst galaxy M82. The spiral arms are recovered when an
axi-symmetric exponential disk is subtracted from the NIR images. The arms
emerge from the ends of the NIR bar and can be traced up to three disk
scalelengths. The winding of the arms is consistent with an m=2 logarithmic
spiral mode of pitch angle 14 degrees. The arms are bluer than the disk in
spite of their detection on the NIR images. If the northern side of the galaxy
is nearer to us, as is normally assumed, the observed sense of rotation implies
trailing arms. The nearly edge-on orientation, high disk surface brightness,
and the presence of a complex network of dusty filaments in the optical images,
are responsible for the lack of detection of the arms in previous studies.


title:
FUSE observations of molecular hydrogen on the line of sight towards
  HD141569A

abstract:
  We present an analysis of the Far Ultraviolet Spectroscopic Explorer (FUSE)
spectrum of HD141569A, a transitional object known to possess a circumstellar
disk. We observe two components of gas at widely different temperatures along
the line of sight. We detect cold H2, which is thermalized up to J=2 at a
kinetic temperature of 51K. Such low temperatures are typical of the diffuse
interstellar medium. Since the line of sight to HD141569A does not pass through
its disk, it appears that we are observing the cold H2 in a low extinction
envelope associated with the high Galactic latitude dark cloud complex L134N,
which is in the same direction and at nearly the same distance as HD141569A.
The column densities of the higher J-levels of H2 suggest the presence of warm
gas along the line of sight. The excitation conditions do not seem to be
consistent with what is generally observed in diffuse interstellar clouds. The
observed radial velocity of the gas implies that the UV spectral lines we
observe are likely interstellar in origin rather than circumstellar, although
our absorption line study does not definitely rule out the possibility that the
warm gas is close to the star. The discovery of such warm gas along the line of
sight may provide evidence for turbulent phenomena in the dark cloud L134N.


title:
On the detection of relativistic magnetic monopoles by deep underwater
  and underice neutrino telescopes

abstract:
  I present here some reflections and very speculative remarks on the detection
of relativistic magnetic monopoles by currently operating deep underwater/ice
neutrino telescopes.


title:
Deriving stellar properties from photometry: maximizing information
  content and minimizing biases

abstract:
  I study the importance of the accurate calibration of photometric systems in
order to produce meaningful comparisons between the observed colors +
magnitudes and model SEDs. Possible sources of errors are discussed and two
examples are analyzed. I show that well-calibrated Tycho-2 photometry is stable
and precise enough for such comparisons. On the contrary, the available
calibrations for Johnson UBV photometry yield relative large systematic errors,
which has prompted me to develop a new, more precise calibration. The
advantages of multicolor photometry over the standard single-color + magnitude
diagrams for the derivation of physical properties of stars (elimination of
degeneracies, inclusion of multiple parameters, avoidance of linearizing
approximations, possibility of a more precise treatment of errors) are
discussed through the use of CHORIZOS, a code developed specifically for this
purpose.


title:
On the Extreme Positive Feedback Star-Forming Mode from Massive and
  Compact Superstar Clusters

abstract:
  The force of gravity acting within the volume occupied by young, compact and
massive superstar clusters, is here shown to drive in situ all the matter
deposited by winds and supernovae into several generations of star formation.
These events are promoted by radiative cooling which drains the thermal energy
of the ejected gas causing its accumulation to then rapidly exceed the
gravitational instability criterion. A detailed account of the integrated
ionizing radiation and mechanical luminosity as a function of time is here
shown to lead to a new stationary solution. In this, the mass deposition rate
$\dot M$, instead of causing a wind as in the adiabatic solution, turns into a
positive feedback star-forming mode equal to the star formation rate. Some of
the implications of this extreme positive feedback mode are discussed.


title:
Discovery of the Binary Pulsar PSR B1259-63 in Very-High-Energy Gamma
  Rays around Periastron with H.E.S.S

abstract:
  We report the discovery of very-high-energy (VHE) gamma-ray emission of the
binary system PSR B1259-63/SS 2883 of a radio pulsar orbiting a massive,
luminous Be star in a highly eccentric orbit. The observations around the 2004
periastron passage of the pulsar were performed with the four 13 m Cherenkov
telescopes of the H.E.S.S. experiment, recently installed in Namibia and in
full operation since December 2003. Between February and June 2004, a gamma-ray
signal from the binary system was detected with a total significance above 13
sigma. The flux was found to vary significantly on timescales of days which
makes PSR B1259-63 the first variable galactic source of VHE gamma-rays
observed so far. Strong emission signals were observed in pre- and
post-periastron phases with a flux minimum around periastron, followed by a
gradual flux decrease in the months after. The measured time-averaged energy
spectrum above a mean threshold energy of 380 GeV can be fitted by a simple
power law F_0(E/1 TeV)^-Gamma with a photon index Gamma =
2.7+-0.2_stat+-0.2_sys and flux normalisation F_0 = (1.3+-0.1_stat+-0.3_sys)
10^-12 TeV^-1 cm^-2 s^-1. This detection of VHE gamma-rays provides unambiguous
evidence for particle acceleration to multi-TeV energies in the binary system.
In combination with coeval observations of the X-ray synchrotron emission by
the RXTE and INTEGRAL instruments, and assuming the VHE gamma-ray emission to
be produced by the inverse Compton mechanism, the magnetic field strength can
be directly estimated to be of the order of 1 G.


title:
Analytic Gravitational-Force Calculations for Models of the Kuiper Belt,
  with Application to the Pioneer Anomaly

abstract:
  We use analytic techniques to study the gravitational force that would be
produced by different Kuiper-Belt mass distributions. In particular, we study
the 3-dimensional rings (and wedge) whose densities vary as the inverse of the
distance, as a constant, as the inverse-squared of the distance, as well as
that which varies according to the Boss-Peale model. These analytic
calculations yield physical insight into the physics of the problem. They also
verify that physically viable models of this type can produce neither the
magnitude nor the constancy of the Pioneer anomaly.


title: On the new short orbital period cataclysmic variable Halpha0242-2802

abstract:
  We present results from our phase-resolved spectroscopy of the newly
identified cataclysmic variable Halpha0242-2802. Halpha0242-2802 was identified
from a deep UK Schmidt Halpha-R band survey as a candidate cataclysmic
variable. Although initial spectroscopy revealed an optical spectrum very
similar to that of the famous short orbital period system WZ Sge, the analysis
of our data shows that this is not the case. Halpha0242-28 differs from WZ Sge
in both the accretion disk structure and the orbital period. In particular,
Halpha0242-28 appears to be a system which has not reached the orbital period
minimum, yet.


title: IMF biases and how to correct them

abstract:
  We discuss possible sources of biases in the determination of the initial
mass function (IMF) introduced by the binning of the data, the uncertainty in
the determinations of masses, and the existence of unresolved multiple systems.
Those three effects tend to produce IMFs that are flatter than the real one. We
analyze the importance of each effect and suggest techniques that minimize or
eliminate the biases. We also report the detection of the first astrometric
binary system composed of two very-early O-type stars, HD 93129 A.


title:
Cosmography, Decelerating Past, and Cosmological Models: Learning the
  Bayesian Way

abstract:
  In this paper, using a significantly improved version of the
model-independent, cosmographic approach to cosmology (John, M. V. 2004, ApJ,
614, 1), we address an important question: Was there a decelerating past for
the universe? To answer this, the Bayes's probability theory is employed, which
is the most appropriate tool for quantifying our knowledge when it changes
through the acquisition of new data. The cosmographic approach helps to sort
out the models in which the universe was always accelerating from those in
which it decelerated for at least some time in the period of interest. Bayesian
model comparison technique is used to discriminate these rival hypotheses with
the aid of recent releases of supernova data. We also attempt to provide and
improve another example of Bayesian model comparison, performed between some
Friedmann models, using the same data. Our conclusion, which is consistent with
other approaches, is that the apparent magnitude-redshift data alone cannot
discriminate these competing hypotheses. We also argue that the lessons learnt
using Bayesian theory are extremely valuable to avoid frequent U-turns in
cosmology.


title: Metals in Star-Forming Galaxies at High Redshift

abstract:
  The chemical composition of high-redshift galaxies is an important property
that gives clues to their past history and future evolution. Measuring
abundances in distant galaxies with current techniques is often a challenge,
and the canonical metallicity indicators can often not be applied. I discuss
currently available metallicity indicators based on stellar and interstellar
absorption and emission lines, and assess their limitations and systematic
uncertainties. Recent studies suggest that star-forming galaxies at redshift
around 3 have heavy-element abundances already close to solar, in agreement
with predictions from cosmological models.


title:
Seismic analysis of the second ionization region of helium in the Sun:
  I. Sensitivity study and methodology

abstract:
  The region of the second ionization of helium in the Sun is a narrow layer
near the surface. Ionization induces a local change of the adiabatic exponent
$\Gamma_1$, which produces a characteristic signature in the frequencies of
p-modes. By adapting the method developed by (Monteiro et al. 1994), we propose
a methodology for determining the properties of this region by studying such a
signature in the frequencies of oscillation.
  Using solar data we illustrate how the signal from the helium ionization zone
can be isolated. Using solar models with different physics -- theory of
convection, equation of state and low temperature opacities -- we establish how
the characteristics of the signal depend on the different aspects contributing
to the structure in the ionization layer. We further discuss how the method can
be used to measure the solar helium abundance in the envelope and to constrain
the physics affecting this region of the Sun.
  The potential usefulness of the method we propose is shown. It may complement
other inversion methods developed to study the solar structure and to determine
the envelope helium abundance.


title:
The Cornell High-order Adaptive Optics Survey for Brown Dwarfs in
  Stellar Systems-I: Observations, Data Reduction, and Detection Analysis

abstract:
  In this first of a two-paper sequence, we report techniques and results of
the Cornell High-order Adaptive Optics Survey for brown dwarf companions
(CHAOS). At the time of this writing, this study represents the most sensitive
published population survey of brown dwarf companions to main sequence stars,
for separation akin to our own outer solar system. The survey, conducted using
the Palomar 200-inch Hale Telescope, consists of K-short coronagraphic
observations of 80 main sequence stars out to 22 parsecs. At 1 arcsecond
separations from a typical target system, the survey achieves median
sensitivities 10 magnitudes fainter than the parent star. In terms of companion
mass, the survey achieves typical sensitivities of 25 Jupiter masses (1 Gyr),
50 Jupiter masses (solar age), and 60 Jupiter masses (10 Gyr), using
evolutionary models of Baraffe et al. (2003). Using common proper motion to
distinguish companions from field stars, we find that no systems show positive
evidence of a substellar companion (searchable separation 1-15 arcseconds
[projected separation ~ 10-155 AU at the median target distance]). In the
second paper of the series we shall present our Monte Carlo population
simulations.


title: A Deep Infrared Search for AXP 1E 1841-045

abstract:
  Multi-colour (JHKs) imaging and photometry of the field of the Anomalous
X-ray Pulsar AXP 1E 1841-045 is analysed in the light of new, accurate
coordinates from Chandra (Wachter et al, 2004). From excellentquality images,
we find multiple sources in and around the position error circle. Of these,
none can be confidently identified as the infrared counterpart. The limiting
magnitudes reached were J=22.1, H=20.7 and Ks=19.9$ (95% confidence).


title:
Extragalactic Globular Clusters: Old Spectroscopic Ages and New Views on
  Their Formation

abstract:
  We present the results of a meta-analysis of Keck spectra of extragalactic
globular clusters (GCs) in a sample of eight galaxies, ranging from dwarfs to
massive ellipticals. We infer ages for the metal-poor and metal-rich GCs in
these galaxies through comparisons to Galactic GCs. Both subpopulations appear
to be no younger than their Galactic counterparts, with ages ~> 10 Gyr. This is
the largest sample of galaxies for which ages have been constrained
spectroscopically. Our results support the formation of most GCs in massive
galaxies at high redshift. We propose a scenario for the formation of GC
subpopulations that synthesizes aspects of both accretion and in situ
approaches in the context of galaxy formation through hierarchical merging.


title: Preservation of Cuspy Profiles in Disk Galaxy Mergers

abstract:
  We carried out three self-consistent $N$-body simulations of galaxy mergers,
with a cuspy dark matter profile, in order to study if the inner dark density
slope is preserved in the remnants. In these simulations the progenitors
include both a stellar disk and an intrinsic angular momentum for the halos,
unlike previous similar studies. The mass-ratios of progenitor galaxies are
about 1:1, 1:3 and 1:10. We find that the initial cuspy density profile of the
dark halos is preserved in the remnants for the cases considered here.


title: Exploring Terrestrial Planet Formation in the TW Hydrae Association

abstract:
  Spitzer Space Telescope infrared measurements are presented for 24 members of
the TW Hydrae association (TWA). High signal-to-noise 24-micron (um) photometry
is presented for all of these stars, including 20 stars that were not detected
by IRAS. Among these 20 stars, only a single object, TWA 7, shows excess
emission at 24um and at the level of only 40% above the star's photosphere. TWA
7 also exhibits a strong 70um excess that is a factor of 40 brighter than the
stellar photosphere at this wavelength. At 70um, an excess of similar magnitude
is detected for TWA 13, though no 24um excess was detected for this binary. For
the 18 stars that failed to show measurable IR excesses, the sensitivity of the
current 70um observations does not rule out substantial cool excesses at levels
10-40x above their stellar continua. Measurements of two T Tauri stars, TW Hya
and Hen 6-300, confirm that their spectacular IR spectral energy distributions
(SEDs) do not turn over even by 160um, consistent with the expectation for
their active accretion disks. In contrast, the Spitzer data for the luminous
planetary debris systems in the TWA, HD 98800B and HR 4796A, are consistent
with single-temperature blackbody SEDs. The major new result of this study is
the dramatic bimodal distribution found for the association in the form of
excess emission at a wavelength of 24um, indicating negligible amounts of warm
(>100 K) dust and debris around 20 of 24 stars in this group of very young
stars. This bimodal distribution is especially striking given that the four
stars in the association with strong IR excesses are >100x brighter at 24um
than their photospheres.


title:
Interplanetary coronal mass ejection effect on the muon flux at sea
  level

abstract:
  We present the results of 720 hours of observations of transient solar events
at ground level, during the summer season 2005 (Souther Hemisphere). Data were
taken with the TUPI muon telescope, working at a high counting rate (up to 100
KHz) and always pointing on the IMF lines (45 degrees of pitch angle). An
anti-correlation among the arrival of keV protons (observed by EPAM detector
aboard the ACE spacecraft) and sudden depressions in the muon flux at sea level
have been observed. The phenomena is discussed in the context that they can be
considered as mini-Forbush, caused by a shielding effect of the passage of a
disturbance (shock and plasma) and may be a signature of interplanetary
manifestations of coronal mass ejections.


title:
Tentative Identification of Interstellar Dust in the Nose of the
  Heliosphere

abstract:
  Observations of the weak polarization of light from nearby stars, reported by
Tinbergen (1982), are consistent with polarization by small, radius <0.14
microm, interstellar dust grains entrained in the magnetic wall of the
heliosphere. The direction of maximum polarization is offset by ~35 deg from
the heliosphere nose, and extends to low ecliptic latitudes. An offset is found
between the direction of the best aligned dust grains, and the upwind direction
of the undeflected large interstellar grains seen by Ulysses and Galileo. In
the aligned-grain region, the strength of polarization anti-correlates with
ecliptic latitude, indicating that the magnetic wall is predominantly at
negative ecliptic latitudes, which is consistent with predictions of Linde
(1998). These data are consistent with an interstellar magnetic field tilt of
60 deg with respect to the ecliptic plane, and parallel to the galactic plane.
Interstellar dust grains captured in the heliosheath may also introduce a weak,
but important, large scale contaminant for the cosmic microwave background
signal with a symmetry consistent with the relative tilts of \Bis and the
ecliptic.


title:
Constraints on the Process that Regulates the Growth of Supermassive
  Black Holes Based on the Intrinsic Scatter in the M_bh-sigma Relation

abstract:
  We show that the observed scatter in the relations between the mass of
supermassive black holes (SMBHs), M_bh, and the velocity dispersion sigma or
mass M_sph of their host spheroid, place interesting constraints on the process
that regulates SMBH growth in galaxies. When combined with the observed
properties of early-type SDSS galaxies, the observed intrinsic scatters imply
that SMBH growth is regulated by the spheroid velocity dispersion rather than
its mass. The M_bh-M_sph relation is therefore a by-product of a more
fundamental M_bh-sigma relation. We construct a theoretical model for the
scatter among baryon modified dark matter halo profiles, out of which we
generate a population of spheroid hosts and show that these naturally lead to a
relation between effective radius and velocity dispersion of the form R_sph ~
sigma^1.5 with a scatter of ~0.2dex, in agreement with the corresponding
projection of the fundamental plane for early type galaxies in SDSS. At the
redshift of formation, our model predicts the minimum scatter that SMBHs can
have at fixed velocity dispersion or spheroid mass under different formation
scenarios. We also estimate the additional scatter that is introduced into
these relations through collisionless mergers of purely stellar spheroids at
z<1. We find that the observed scatter in the M_bh-sigma and M_bh-M_sph
relations preclude the properties of dark matter halos from being the governing
factor in SMBH growth. Finally, we show that SMBH growth governed by the
properties of the host spheroid can lead to the observed values of scatter in
the M_bh-sigma and M_bh-M_sph relations, only if the SMBH growth is limited by
momentum or energy feedback over the dynamical time of the host spheroid.


title:
The optical counterpart of XTE J0929-314, the third transient
  millisecond X-ray pulsar

abstract:
  A blue and variable optical counterpart of the X-ray transient XTE J0929-314
was identified on 2002 May 1. We conducted frequent BVRI broadband photometry
on this object using the Mt Canopus 1-m telescope during May and June until it
had faded to below 21'st magnitude. Nearly continuous I band CCD photometry on
2002 May 2, 3 and 4 revealed a ~ 10 % sinusoidal modulation at the binary
period lasting ~ 6 cycles during the latter half of May 2. The phase indicates
that the modulation may be due to a combination of emission by a hot spot on
the disc and X-ray heating of the secondary. The emission generally trended
bluer with B-I decreasing by 0.6 magnitudes during the observations but there
were anomalous changes in colour during the first few days after optical
identification when the I band flux decreased slightly while fluxes in other
bands increased. Spectral analysis of the BVRI broadband photometry show
evidence of a variable excess in the R and I bands. We suggest that this may be
due to synchrotron emission in matter flowing out of the system and note that
similar processes may have been responsible for anomalous V and I band
measurements in 1998 of the persistent millisecond X-ray pulsar SAX
J1808.4-3658.


title: Disc radius variations in binaries

abstract:
  A thermal/viscous instability of the accretion disc arising when hydrogen is
partially ionized is the most popular explanation of the outbursts of both
dwarf novae (DN) and soft X-ray transients (SXT). During an outburst, the disc
expands and may reach the 3:1 resonance radius, triggering the so-called tidal
instability. The consequences of such an instability are still debated; it is
generally accepted that it results in the observed periodic modulation in SU
UMa systems, and to large amplitude outbursts in these systems, the latter
being more controversial. We discuss both the theoretical and observational
evidences for such radius variations in DNs and SXTs, and the consequences of
the application of the tidal instability in SXT.


title: Pulsating stars in the ASAS-3 database. I. Beta Cephei stars

abstract:
  We present results of an analysis of the ASAS-3 data for short-period
variables from the recently published catalogue of over 38 000 stars. Using the
data available in the literature we verify the results of the automatic
classification related to $\beta$ Cephei pulsators. In particular, we find that
14 stars in the catalogue can be classified unambiguously as new $\beta$ Cephei
stars. By means of periodogram analysis we derive the frequencies and
amplitudes of the excited modes. The main modes in the new $\beta$ Cephei stars
have large semi-amplitudes, between 35 and 80 mmag. Up to four modes were found
in some stars. Two (maybe three) new $\beta$ Cephei stars are members of
southern young open clusters: ASAS 164409-4719.1 belongs to NGC 6200, ASAS
164630-4701.2 is a member of Hogg 22, and ASAS 164939-4431.7 could be a member
of NGC 6216.
  We also analyze the photometry of four known $\beta$ Cephei stars in the
ASAS-3 catalogue, namely IL Vel, NSV 24078, V1449 Aql and SY Equ. Finally, we
discuss the distribution of $\beta$ Cephei stars in the Galaxy.


title: The application of slim disk models to ULX: the case of M33 X-8

abstract:
  A comparative XMM-Newton archival data spectral study of the ultraluminous
X-ray source (ULX) M33 X-8 has been performed by using both the standard disk
model and the newly developed slim disk models. The results of this analysis
tend to confirm the hypothesis that M33 X-8 is an X-ray binary with a
stellar-mass black hole accreting at super-Eddington rate.


title:
Fourier Resolved Spectroscopy of the XMM-Newton Observations of MCG
  -6-30-15

abstract:
  We study the Frequency Resolved Spectra of the Seyfert galaxy MCG -6-30-15
obtained during two recent XMM-Newton observations. Splitting the Fourier
spectra in soft (<2 keV) and hard (>2 keV) bands, we find that the soft band
has a variability amplitude larger than the hard one on time scales longer than
10 ksec, while the opposite is true on time scales shorter than 3 ksec. Both
the soft and hard band spectra are well fitted by power laws of different
indices. The spectra of the hard band become clearly softer as the Fourier
Frequency decreases from 7x10^{-4} Hz to 10^{-5} Hz, while the spectral slope
of the soft band power law component is independent of the Fourier frequency.
The well known broad Fe Ka feature is absent at all frequency bins; this result
implies that this feature is not variable on time scales shorter than ~10^5
sec, in agreement with recent line variability studies. Strong spectral
features are also present in the soft X-ray band (at E~0.7), clearly
discernible in all Fourier Frequency bins. This fact is consistent with the
assumption that they are due to absorption by intervening matter within the
source.


title: Integral Field Spectroscopy of Faint Haloes of Planetary Nebulae

abstract:
  We present the first integral field spectroscopy observations of the two
planetary nebulae NGC3242 and NGC4361 with the VIMOS instrument attached to
VLT-UT3. By co-adding a large number of spaxels we reach an emission line
detection limit of 5.E-18 erg cm^{-2} s^{-1} arcsec^{-2}. In the case of
NGC3242, we succeed in determining some properties of the halo. The radial
surface brightness profile in [OIII] implies increasing mass loss before the
formation of the PN. Traces of the mysterious 'rings' are clearly visible. We
find for the first time an apparent temperature gradient across a halo: from
about 16000 K close to the shell/halo transition to 20000 K at the halo's outer
edge. No line emission is seen in the suspected halo region of NGC4361 down to
the sensitivity limit.


title: Spectroscopic classification of cataclysmic variable candidates

abstract:
  We present low resolution optical spectroscopy for six cataclysmic variable
candidates and the old nova V888 Cen. We confirm the classification as
cataclysmic variable for LB 9963 and FQ Mon, while the other four candidates
turn out to be different type of stars. We discuss the individual spectra and
pay special attention to the mass transfer rate and disc temperature and
density of the three cataclysmic variables.


title: Electromagnetic extraction of energy from Kerr black holes

abstract:
  We elucidate the `right' process for energy extraction from Kerr black holes
through `FFDE' magnetospheres, free from causality violation. It is shown that
the magnetosphere of a Kerr black hole possesses the double-structure,
consisting of the inner and outer magnetospheres with the pair-creation gap
between them and with respective unipolar batteries at the inner and outer
surfaces of the gap.


title: Massive Young Stellar Objects in high-mass star-forming regions

abstract:
  High-quality K-band spectra of point sources, deeply embedded in massive
star-forming regions, have revealed a population of 20 young massive stars
showing no photospheric absorption lines, but only emission lines. The K-band
spectra exhibit one or more features commonly associated with massive Young
Stellar Objects surrounded by circumstellar material: a very red color (J-K) =
2, CO bandhead emission, hydrogen emission lines (sometimes doubly peaked), and
FeII and/or MgII emission lines. The CO emission comes from a relatively dense
(~10^10 cm^(-3)) and hot (T ~ 2000-5000 K) region, sufficiently shielded from
the intense UV radiation field of the young massive star. Modeling of the
CO-first overtone emission shows that the CO gas is located within 5 AU of the
star. The hydrogen emission is produced in an ionized medium exposed to UV
radiation. The best geometrical configuration is a dense and neutral
circumstellar disk causing the CO bandhead emission, and an ionized upper layer
where the hydrogen lines are produced. We argue that the circumstellar disk is
likely a remnant of the accretion via a circumstellar disk.


title: Comment on non-Gaussianity in hybrid inflation

abstract:
  In the literature there have been incompatible estimates for the amount of
non-Gaussianity in hybrid inflation. In this note we point out the sources for
the discrepancies and show that the results for the amount of non-Gaussianity
in hybrid inflation obtained by two different methods, namely, perturbing
Einstein equation to second order and the separate universe approach, indeed
are compatible. This provides confidence in the methods themselves and in the
actual computation of non-Gaussianities.


title:
X-rays from the Type II quasar in the hyperluminous infrared galaxy IRAS
  F15307+3252

abstract:
  We report the detection of X-ray emission from the hyperluminous infrared
galaxy IRAS F15307+3252 at z=0.93 and its properties obtained from XMM-Newton
observations. Although the X-ray emission is very faint and the data are noisy,
a prominent line-like feature in the observed 3-4 keV range is inferred from
both photometric and spectroscopic techniques. It indicates an X-ray spectrum
dominated by 6.4 keV Fe K emission and the presence of a Compton-thick AGN. Our
estimate of the luminosity of the illuminating source (L(2-10keV)>=1e45 erg/s),
required to produce the observed Fe K emission in reflection from cold matter,
means that the hidden quasar nucleus accounts for a significant fraction of the
large bolometric luminosity. The soft X-ray emission below 2 keV is found to be
spatially extended and probably of a separate origin. The temperature and
bolometric luminosity (kT=2 keV and L(bol,CL)=1e44 erg/s) obtained from a
thermal spectrum place this X-ray source on the L-Tx relation of galaxy
clusters. The possible association with a galaxy cluster can be added to the
list of remarkable similarities between IRAS F15307+3252 and another
hyperluminous infrared galaxy IRAS 09104+4109 (z=0.44), both of which have
bolometric luminosities dominated by hidden quasar nuclei. Our result on IRAS
F15307+3252 illustrates how difficult it is to detect Compton thick Type II
quasars at z>=1, particularly if their bolometric outputs do not rival the
hyperluminous population.


title: X-ray chemistry in envelopes around young stellar objects

abstract:
  We present chemical models of the envelope of a young stellar object (YSO)
exposed to a central X-ray source. The models are applied to the massive
star-forming region AFGL 2591 for different X-ray fluxes. The total X-ray
ionization rate is dominated by the `secondary' ionization rate of H2 resulting
from fast electrons. The carbon, sulphur and nitrogen chemistries are
discussed. It is found that He+ and H3+ are enhanced and trigger a peculiar
chemistry. Several molecular X-ray tracers are found and compared to tracers of
the far ultraviolet (FUV) field. Like ultraviolet radiation fields, X-rays
enhance simple hydrides, ions and radicals. In contrast to ultraviolet photons,
X-rays can penetrate deep into the envelope and affect the chemistry even at
large distances from the source. Whereas the FUV enhanced species cover a
region of 200-300 AU, the region enhanced by X-rays is >1000 AU. Best-fit
models for AFGL 2591 predict an X-ray luminosity LX > 1e+31 ergs/s with a hard
X-ray spectrum TX > 3e+07 K. Furthermore, we find LX/Lbol ~ 1e-6. The chemistry
of the bulk of the envelope mass is dominated by cosmic-ray induced reactions
rather than by X-ray induced ionization for X-ray luminosities LX < 1e+33
ergs/s. The calculated line intensities of HCO+ and HCS+ show that high-J lines
are more affected than lower J lines by the presence of X-rays due to their
higher critical densities, and that such differences are detectable even with
large aperture single-dish telescopes. Future instruments such as Herschel-HIFI
or SOFIA will be able to observe X-ray enhanced hydrides whereas the
sensitivity and spatial resolution of ALMA is well-suited to measure the size
and geometry of the region affected by X-rays.


title: Mass loss at the lowest stellar masses

abstract:
  We report the discovery of a jet in a [SII] image of Par-Lup3-4, a remarkable
M5-type pre-main sequence object in the Lupus 3 star-forming cloud. The
spectrum of this star is dominated by the emission lines commonly interpreted
as tracers of accretion and outflows. Par-Lup3-4 is therefore at the very
low-mass end of the exciting sources of jets. High resolution spectroscopy
shows that the [SII] line profile is double-peaked, implying that the low
excitation jet is seen at a small angle (probably larger than 8 degrees) with
respect to the plane of the sky. The width of the H_alpha line suggests a
dominating contribution from the accretion columns and from the shocks on the
stellar surface. Unresolved H_alpha emission coming from an object located at
4.2" from Par-Lup3-4 is detected at a position angle ~30 degrees or ~210
degrees, with no counterpart seen either in visible or infrared images.We also
confirm previous evidence of strong mass loss from the very low mass star
LS-RCrA 1, with spectral type M6.5 or later. All its forbidden lines are
blueshifted with respect to the local standard of rest (LSR) of the molecular
cloud at a position very close to the object and the line profile of the [OI]
lines is clearly asymmetric. Thus, the receding jet could be hidden by a disk
which is not seen edge-on. If an edge-on disk does not surround Par-Lup3-4 or
LS-RCrA 1, an alternative explanation, possibly based on the effects of mass
accretion, is required to account for their unusually low luminosities.


title: Fast directional continuous spherical wavelet transform algorithms

abstract:
  We describe the construction of a spherical wavelet analysis through the
inverse stereographic projection of the Euclidean planar wavelet framework,
introduced originally by Antoine and Vandergheynst and developed further by
Wiaux et al. Fast algorithms for performing the directional continuous wavelet
analysis on the unit sphere are presented. The fast directional algorithm,
based on the fast spherical convolution algorithm developed by Wandelt and
Gorski, provides a saving of O(sqrt(Npix)) over a direct quadrature
implementation for Npix pixels on the sphere, and allows one to perform a
directional spherical wavelet analysis of a 10^6 pixel map on a personal
computer.


title:
Helium Recombination Lines as a Probe of Abundance and Temperature
  Problems

abstract:
  The paper presents a simplified formula to determine an electron temperature,
Te(He I), for planetary nebulae (PNe) using the He I 7281/6678 line flux ratio.
In our previous studies of Te(He I) (Zhang et al. 2005), we used the He I line
emission coefficients given by Benjamin et al. (1999). Here we examine the
results of using more recent atomic data presented by Porter et al. (2005). A
good agreement is shown, suggesting that the effect of uncertainties of atomic
data on the resultant Te(He I) is negligible. We also present an analytical
formula to derive electron temperature using the He I discontinuity at 3421 A.
Our analysis shows that Te(He I) values are significantly lower than electron
temperatures deduced from the Balmer jump of H I recombination spectra, Te(H
I), and that inferred from the collisionally excited [O III] nebular-to-auroral
forbidden line flux ratio, Te([O III]). In addition, Te(H I) covers a wider
range of values than either Te(He I) or Te([O III]). This supports the
two-abundance nebular model with hydrogen-deficient material embedded in
diffuse gas of a ``normal'' chemical composition (i.e. ~solar).


title:
Constraints on holographic dark energy from type Ia supernova
  observations

abstract:
  In this paper, we use the type Ia supernovae data to constrain the
holographic dark energy model proposed by Li. We also apply a cosmic age test
to this analysis. We consider in this paper a spatially flat
Friedmann-Robertson-Walker Universe with matter component and holographic dark
energy component. The fit result shows that the case $c<1$ ($c=0.21$) is
favored, which implies that the holographic dark energy behaves as a
quintom-type dark energy. Furthermore, we also perform a joint analysis of
SNe+CMB+LSS to this model; the result is well improved, and still upholds the
quintom dark energy conclusion. The best fit results in our analysis are
$c=0.81$, $\Omega_m^0=0.28$, and $h=0.65$, which lead to the present equation
of state of dark energy $w_0=-1.03$ and the deceleration/acceleration
transition redshift $z_T=0.63$. Finally, an expected SNAP simulation using
$\Lambda$CDM as a fiducial model is performed on this model, and the result
shows that the holographic dark energy model takes on $c<1$ ($c=0.92$) even
though the dark energy is indeed a cosmological constant.


title: Gl86B: a white dwarf orbits an exoplanet host star

abstract:
  In this letter we present our first high contrast NACO/SDI observations of
the exoplanet host star Gl86 and results from NACO spectroscopy. Els et al.
(2001) found a faint co-moving companion located only ~2arcsec east of the
exoplanet host star Gl86A. Our high contrast SDI observations rule out
additional stellar companions from 1AU up to 23AU, and are sensitive for faint
T dwarf companions down to 35MJup. We present evidence for orbital motion of
Gl86B around the exoplanet host star Gl86A, which finally confirms that this is
a bound binary system. With the given photometry from Els et al. (2001) and the
obtained NACO spectroscopy we prove that the companion Gl86B is a cool white
dwarf with an effective temperature of 5000+-500K. This is the first confirmed
white dwarf companion to an exoplanet host star and the first observational
confirmation that planets survive the post main sequence evolution of a star
from which they are separated by only one to two dozen astronomical units
(giant phase and planetary nebula) as expected from theory.


title: Optical Constraints on an X-ray Transient Source in M31

abstract:
  We have detected a transient X-ray source in the M31 bulge through a
continuing monitoring campaign with the Chandra ACIS-I camera. The source was
detected at R.A.=00:42:33.428 +/- 0.11'', Dec.=+41:17:03.37 +/- 0.11'' in only
a single observation taken 2004 May 23. Fortuitous optical HST/ACS imaging of
the transient location prior to the X-ray outburst, along with follow-up
HST/ACS imaging during and after the outburst, reveals no transient optical
source brighter than B (equivalent) = 25.5. The location of the source and its
X-ray properties suggest it is a low mass X-ray binary (LMXB). Assuming the
transient is similar to many Galactic X-ray novae, the X-ray luminosity of (3.9
+/- 0.5) X 10$^{37}$ erg s$^{-1}$ and the upper-limit on the optical luminosity
provide a prediction of <1.6 days for the orbital period of the binary system.


title: Issues with Core-Collapse Supernova Progenitor Models

abstract:
  The status of core collapse supernoova progenitor models is reviewed with a
focus on some of the current uncertainties arising from the difficulties of
modeling important macrophysics and microphysics. In particular, I look at
issues concerned with modeling convection, the implications of the still
uncertain 12C(alpha,gamma)16O reaction rate, the uncertainties involved with
the incorporation of mass loss, rotation, and magnetic fields in the stellar
models, and the possible generation of global instabilities in stellar models
at the late evolutionary stages.


title:
The ACS Virgo Cluster Survey V: SBF Calibration for Giant and Dwarf
  Early-type Galaxies

abstract:
  As part of the Advanced Camera for Survey (ACS) Virgo Cluster Survey, we have
measured Surface Brightness Fluctuations (SBF) in a sample of 100 early-type
Virgo galaxies. Distances derived from these measurements are needed to explore
the three-dimensional structure of the Virgo Cluster, study the intrinsic
parameters of globular clusters associated with the program galaxies, and
compare with the galaxy distances derived from globular cluster luminosity
functions. Our SBF measurements have been performed in the F850LP bandpass of
the Wide Field Channel of the ACS on the Hubble Space Telescope. These are the
first measurements of this kind, and we present the first SBF calibration for
this bandpass. The measured fluctuations depend on galaxy stellar population
variations, which we quantify by galaxy color (g_475-z_850)_0, where g_475 and
z_850 are the galaxy magnitudes, respectively, in the F475W and F850LP ACS
filters. We derive the following calibration for the absolute SBF magnitude
M_850: M_850 = -2.06 +/- 0.04 + (2.0 +/ 0.2) [ (g_475-z_850)_0-1.3 ] in the
range 1.3 <(g_475-z_850)_0 <= 1.6, and M_850 = -2.06 +/- 0.04 + (0.9 +/- 0.2) [
(g_475-z_850)_0-1.3 ] in the range 1.0 <=(g_475-z_850)_0 <= 1.3. Physically,
the two different color regimes correspond to different galaxy types: giant
ellipticals and S0s at the red end, and early-type dwarfs at the blue end. For
the first time in SBF studies, we are able to provide a firm empirical
calibration of SBF in early-type dwarf galaxies. Our results agree with stellar
population model predictions from Bruzual & Charlot (2003).


title: GMOS-IFU Spectroscopy of 167-317 (LV2) Proplyd in Orion

abstract:
  We present high spatial resolution spectroscopic observations of the proplyd
167-317 (LV2) near the Trapezium cluster in the Orion nebula, obtained during
the System Verification run of the Gemini Multi Object Spectrograph (GMOS)
Integral Field Unit (IFU) at the Gemini South Observatory. We have detected 38
forbidden and permitted emission lines associated with the proplyd and its
redshifted jet. We have been able to detect three velocity components in the
profiles of some of these lines: a peak with a 28-33 km/s systemic velocity
that is associated with the photoevaporated proplyd flow, a highly redshifted
component associated with a previously reported jet (which has receding
velocities of about 80-120 km/s with respect to the systemic velocity and is
spatially distributed to the southeast of the proplyd) and a less obvious,
approaching structure, which may possibly be associated with a faint
counter-jet with systemic velocity of (-75 +/- 15) km/s. We find evidences that
the redshifted jet has a variable velocity, with slow fluctuations as a
function of the distance from the proplyd. We present several background
subtracted, spatially distributed emission line maps and we use this
information to obtain the dynamical characteristics over the observed field.
Using a simple model and with the extinction corrected Halpha fluxes, we
estimate the mass loss rate for both the proplyd photoevaporated flow and the
redshifted microjet, obtaining (6.2 +/- 0.6) x 10^{-7} M_sun/year and (2.0 +/-
0.7) x 10^{-8} M_sun/year, respectively.


title:
Black Hole Masses and Host Galaxy Evolution of Radio-loud Active
  Galactic Nuclei

abstract:
  We report stellar velocity dispersion measurements for a sample of 28 AGN
host galaxies including our previous work. Using the mass-dispersion
($M_{\bullet}-\sigma$) and the fundamental plane relations, we estimate the
black hole mass for a sample of 66 BL Lac objects and investigate the role of
black hole mass in the energetics of BL Lac objects. The black hole mass range
for different BL Lac spectral types is similar, $10^{7} < M_{\bullet} < 4
\times 10^{9}$. Neither X-ray nor radio luminosity correlates with black hole
mass. Low-frequency-peaked BL Lac objects have higher Eddington ratios on
average, because of either more beaming or higher intrinsic power. For the
black hole mass range $3 \times 10^{7} < M_{\bullet} < 10^{9}$, the radio
luminosity of BL Lac objects and flat-spectrum radio quasars spans over 4
orders of magnitude, with BL Lac objects being low-power AGNs. We also
investigate the evolution of host galaxies for 39 AGNs out to $z \approx 0.5$
with measuredstellar velocity dispersions. Comparing the mass-to-light ratio
evolution in the observed frame with population synthesis models, we find that
single burst star formation models with $z_{form} = 1.4^{+0.9}_{-0.2} $ are
consistent with the observations. From our $z_{form}=1.4$ model, we estimated
the intrinsic mass-to-light ratio evolution in the Cousins $R$ band, $\Delta
log (M/L)/ \Delta z = -0.502 \pm 0.08$, consistent with that of normal early
type galaxies.


title:
The open cluster initial-final mass relationship and the high-mass tail
  of the white dwarf distribution

abstract:
  Recent studies of white dwarfs in open clusters have provided new constraints
on the initial - final mass relationship (IFMR) for main sequence stars with
masses in the range 2.5 - 6.5 Mo. We re-evaluate the ensemble of data that
determines the IFMR and argue that the IFMR can be characterised by a mean
initial-final mass relationship about which there is an intrinsic scatter. We
investigate the consequences of the IFMR for the observed mass distribution of
field white dwarfs using population synthesis calculations. We show that while
a linear IFMR predicts a mass distribution that is in reasonable agreement with
the recent results from the PG survey, the data are better fitted by an IFMR
with some curvature. Our calculations indicate that a significant (~28%)
percentage of white dwarfs originating from single star evolution have masses
in excess of ~0.8 Mo, obviating the necessity for postulating the existence of
a dominant population of high-mass white dwarfs that arise from binary star
mergers.


title: On the shape of the UHE cosmic ray spectrum

abstract:
  We fit the ultra high energy cosmic ray spectra above 10$^{19}$ eV with
different injection spectra at cosmic ray sources that are uniformly and
homogeneously distributed in the Universe. We conclude that the current UHE
spectra are consistent with power laws of index $\alpha$ between 2.4 and 2.7.
There is a slow dependence of these indices on the cosmological evolution of
the cosmic ray sources, which in this model determines the end of the galactic
cosmic rays spectrum.


title: Observations of Mkn 421 in 2004 with H.E.S.S. at large zenith angles

abstract:
  Mkn 421 was observed during a high flux state for nine nights in April and
May 2004 with the fully operational High Energy Stereoscopic System (H.E.S.S.)
in Namibia. The observations were carried out at zenith angles of
60$^\circ$--65$^\circ$, which result in an average energy threshold of 1.5 TeV
and a collection area reaching 2~km$^2$ at 10~TeV. Roughly 7000 photons from
Mkn~421 were accumulated with an average gamma-ray rate of 8 photons/min. The
overall significance of the detection exceeds 100 standard deviations. The
light-curve of integrated fluxes above 2~TeV shows changes of the diurnal flux
up to a factor of 4.3. For nights of high flux, intra-night variability is
detected with a decay time of less than 1 hour. The time averaged energy
spectrum is curved and is well described by a power-law with a photon index
$\egamm$ and an exponential cutoff at $\ecut$~TeV and an average integral flux
above 2~TeV of 3 Crab flux units. Significant variations of the spectral shape
are detected with a spectral hardening as the flux increases. Contemporaneous
multi-wavelength observations at lower energies (X-rays and gamma-rays above
$\approx 300$~GeV) indicate smaller relative variability amplitudes than seen
above 2~TeV during high flux state observed in April 2004.