title:
Evolution of Circumstellar Disks Around Normal Stars: Placing Our Solar
  System in Context

abstract:
  Over the past 10 years abundant evidence has emerged that many (if not all)
stars are born with circumstellar disks. Understanding the evolution of
post-accretion disks can provide strong constraints on theories of planet
formation and evolution. In this review, we focus on developments in
understanding: a) the evolution of the gas and dust content of circumstellar
disks based on observational surveys, highlighting new results from the Spitzer
Space Telescope; b) the physical properties of specific systems as a means to
interpret the survey results; c) theoretical models used to explain the
observations; d) an evolutionary model of our own solar system for comparison
to the observations of debris disks around other stars; and e) how these new
results impact our assessment of whether systems like our own are common or
rare compared to the ensemble of normal stars in the disk of the Milky Way.


title:
Toward Understanding the origin of the Fundamental Plane for Early-Type
  Galaxies

abstract:
  We present a panoramic review of several observational and theoretical
aspects of the modern astrophysical research about the origin of the
Fundamental Plane (FP) relation for Early-Type Galaxies (ETGs). The discussion
is focused on the problem of the tilt and the tightness of the FP, and on the
attempts to derive the luminosity evolution of ETGs with redshift. Finally, a
number of observed features in the FP are interpreted from the standpoint of a
new theoretical approach based on the two-component tensor virial theorem.


title:
Adaptive Optics Correction of the Wavefront Distortions Induced by
  Segments Misalignment in Extremely Large Telescope

abstract:
  The capability of the adaptive optics to correct for the segmentation error
is analyzed in terms of the residual wavefront RMS and the power spectral
density of the phase. The analytical model and the end-to-end simulation give
qualitatively equal results justifying the significance of the geometrical
matching between segmentation geometry and the actuators/subaperture
distribution of the adaptive optics. We also show that the design of the
wavefront sensor is rather critical.


title:
Observations of V838 Mon and the nearby region in the CO J = 1-0, 2-1
  and 3-2 transitions

abstract:
  We present observations of V838 Mon and its close vicinity in the three
lowest rotational transitions of CO. The J = 2-1 and 3-2 data were obtained
using the 3 m KOSMA telescope. They include on-the-fly maps covering a large
area (~3.4 sq. deg.) around V838 Mon and long integrations on the star
position. Complementary observations in the CO J = 1-0 transition were obtained
using the 13.7 m Delingha telescope. The star position as well as 25 other
points preselected in the near vicinity of the object have been measured in
this transition.
  We report on a detection of two narrow emission components in J = 2-1 and 3-2
transitions at the position of V838 Mon. Lines were found at radial velocities
of V_lsr=53.3 km/s and V_lsr=-11.0 km/s. Their origin is unclear. We also
shortly discuss results of the observations of the vicinity of V838 Mon.


title:
The VLT-FLAMES survey of massive stars: Mass loss and rotation of
  early-type stars in the SMC

abstract:
  We have studied the optical spectra of a sample of 31 O- and early B-type
stars in the Small Magellanic Cloud, 21 of which are associated with the young
massive cluster NGC 346. Stellar parameters are determined using an automated
fitting method. Comparison with predictions of stellar evolution that account
for stellar rotation does not result in a unique age, though most stars are
best represented by an age of 1-3 Myr. The present day v_sini distribution of
the 21 dwarf stars in our sample is consistent with an underlying rotational
velocity (v_r) distribution that can be characterised by a mean velocity of
about 160-190 km/s and an effective half width of 100-150 km/s. The v_r
distribution must include a small percentage of slowly rotating stars. If
predictions of the time evolution of the equatorial velocity for massive stars
within the environment of the SMC are correct, the young age of the cluster
implies that this underlying distribution is representative for the initial
rotational velocity distribution. The location in the Hertzsprung-Russell
diagram of the stars showing helium enrichment is in qualitative agreement with
evolutionary tracks accounting for rotation, but not for those ignoring v_r.
The mass loss rates of the SMC objects having luminosities of log L/L_sun > 5.4
are in excellent agreement with predictions. However, for lower luminosity
stars the winds are too weak to determine M_dot accurately from the optical
spectrum. Two of three spectroscopically classified Vz stars from our sample
are located close to the theoretical zero age main sequence, as expected.


title:
First direct detection of a Keplerian rotating disk around the Be star
  $\alpha$ Arae using the VLTI/AMBER instrument

abstract:
  Aims. We aim to study the geometry and kinematics of the disk around the Be
star $\alpha$ Arae as a function of wavelength, especially across the
Br$\gamma$ emission line. The main purpose of this paper is to answer the
question about the nature of the disk rotation around Be stars. Methods. We use
the VLTI/AMBER instrument operating in the K band which provides a gain by a
factor 5 in spatial resolution compared to previous VLTI/MIDI observations.
Moreover, it is possible to combine the high angular resolution provided with
the (medium) spectral resolution of AMBER to study the kinematics of the inner
part of the disk and to infer its rotation law. Results. We obtain for the
first time the direct evidence that the disk is in keplerian rotation,
answering a question that occurs since the discovery of the first Be star
$\gamma$ Cas by father Secchi in 1866. We also present the global geometry of
the disk showing that it is compatible with a thin disk + polar enhanced winds
modeled with the SIMECA code. We found that the disk around $\alpha$ Arae is
compatible with a dense equatorial matter confined in the central region
whereas a polar wind is contributing along the rotational axis of the central
star. Between these two regions the density must be low enough to reproduce the
large visibility modulus (small extension) obtained for two of the four VLTI
baselines. Moreover, we obtain that $\alpha$ Arae is rotating very close to its
critical rotation. This scenario is also compatible with the previous MIDI
measurements.


title:
The VLT-FLAMES Survey of Massive Stars: Observations centered on the
  Magellanic Cloud clusters NGC 330, NGC 346, NGC 2004, and the N11 region

abstract:
  We present new observations of 470 stars using the Fibre Large Array
Multi-Element Spectrograph (FLAMES) instrument in fields centered on the
clusters NGC 330 and NGC 346 in the Small Magellanic Cloud (SMC), and NGC 2004
and the N11 region in the Large Magellanic Cloud (LMC). A further 14 stars were
observed in the N11 and NGC 330 fields using the Ultraviolet and Visual Echelle
Spectrograph (UVES) for a separate programme. Spectral classifications and
stellar radial velocities are given for each target, with careful attention to
checks for binarity. In particular we have investigated previously unexplored
regions around the central LH9/LH10 complex of N11, finding ~25 new O-type
stars from our spectroscopy. We have observed a relatively large number of
Be-type stars that display permitted Fe II emission lines. These are primarily
not in the cluster cores and appear to be associated with classical Be-type
stars, rather than pre main-sequence objects. The presence of the Fe II
emission, as compared to the equivalent width of H$\alpha$, is not obviously
dependent on metallicity. We have also explored the relative fraction of Be- to
normal B-type stars in the field-regions near to NGC 330 and NGC 2004, finding
no strong evidence of a trend with metallicity when compared to Galactic
results. A consequence of service observations is that we have reasonable
time-sampling in three of our FLAMES fields. We find lower limits to the binary
fraction of O- and early B-type stars of 23 to 36%. One of our targets
(NGC346-013) is especially interesting with a massive, apparently hotter, less
luminous secondary component.


title:
High energy neutrino yields from astrophysical sources I: Weakly
  magnetized sources

abstract:
  We calculate the yield of high energy neutrinos produced in astrophysical
sources with negligible magnetic fields varying their interaction depth from
nearly transparent to opaque. We take into account the scattering of
secondaries on background photons as well as the direct production of neutrinos
in decays of charm mesons. If multiple scattering of nucleons becomes
important, the neutrino spectra from meson and muon decays are strongly
modified with respect to transparent sources. Characteristic for neutrino
sources containing photons as scattering targets is a strong energy-dependence
of the ratio $R^0$ of $\nu_\mu$ and $\nu_e$ fluxes at the sources, ranging from
$R^0=\phi_\mu/\phi_e\sim 0$ below threshold to $R^0\sim 4$ close to the energy
where the decay length of charged pions and kaons equals their interaction
length on target photons. Above this energy, the neutrino flux is strongly
suppressed and depends mainly on charm production.


title: Proto-Clusters with Evolved Populations around Radio Galaxies at z~2.5

abstract:
  We report a discovery of proto-cluster candidates around high redshift radio
galaxies at z~2.5 on the basis of clear statistical excess of colour-selected
galaxies around them seen in the deep near-infrared imaging data obtained with
CISCO on Subaru Telescope. We have observed six targets, all at similar
redshifts at z~2.5, and our data reach to J=23.5, H=22.6 and K=21.8 (5 sigma)
and cover a 1.6' x 1.6' field centered on each radio galaxy. We apply colour
cuts in JHKs in order to exclusively search for galaxies located at high
redshifts, z>2. Over the magnitude range of 19.5<K<21.5 we see a significant
excess of red galaxies with J-K>2.3 by a factor of two around the combined
radio galaxies fields compared to those found in the general field of GOODS
South. The excess of galaxies around the radio galaxies fields becomes more
than factor of three around 19.5<K<20.5 when the two-colours cuts are applied
with JHKs. Such overdensity of the colour-selected galaxies suggest that those
fields tend to host high density regions at high redshifts, although there
seems to be the variety of the density of the colour-selected galaxies in each
field. In particular, two radio galaxies fields out of the six observed fields
show very strong density excess and these are likely to be proto-clusters
associated to the radio galaxies which would evolve into rich clusters of
galaxies dominated by old passively evolving galaxies.


title:
An Interacting Dark Energy Model for the Expansion History of the
  Universe

abstract:
  We explore a model of interacting dark energy where the dark energy density
is related by the holographic principle to the Hubble parameter, and the decay
of the dark energy into matter occurs at a rate comparable to the current value
of the Hubble parameter. We find this gives a good fit to the observational
data supporting an accelerating Universe, and the model represents a possible
alternative interpretation of the expansion history of the Universe.


title:
The VLT-FLAMES Survey of Massive Stars: Stellar parameters and
  rotational velocities in NGC3293, NGC4755 and NGC6611

abstract:
  An analysis is presented of VLT-FLAMES spectroscopy for three Galactic
clusters, NGC3293, NGC4755 and NGC6611. Non-LTE model atmosphere calculations
have been used to estimate effective temperatures (from either the helium
spectrum or the silicon ionization equilibrium) and gravities (from the
hydrogen spectrum). Projected rotational velocities have been deduced from the
helium spectrum (for fast and moderate rotators) or the metal line spectrum
(for slow rotators). The observed Hertzsprung-Russell diagrams are compared
with theoretical predictions and some discrepancies including differences in
the main sequence luminosities are discussed. Cluster ages have been deduced
and evidence for non-coeval star formation is found for all three of the
clusters. Projected rotational velocities for targets in the older clusters,
NGC3293 and NGC4755, have been found to be systematically larger than those for
the field, confirming recent results in other similar age clusters. The
distribution of projected rotational velocities are consistent with a Gaussian
distribution of intrinsic rotational velocities. For the relatively unevolved
targets in the older clusters, NGC3293 and NGC4755, the peak of the velocity
distribution would be 250km/s with a full-width-half-maximum of approximately
180km/s. For NGC6611, the sample size is relatively small but implies a lower
mean rotational velocity. This may be evidence for the spin-down effect due to
angular momentum loss through stellar winds, although our results are
consistent with those found for very young high mass stars. For all three
clusters we deduce present day mass functions with Gamma-values in the range of
-1.5 to -1.8, which are similar to other young stellar clusters in the Milky
Way (Abridged).


title: The Evolution of the ISM in the Mildly Disturbed Spiral Galaxy NGC 4647

abstract:
  We present matched-resolution maps of HI and CO emission in the Virgo Cluster
spiral NGC 4647. The galaxy shows a mild kinematic disturbance in which one
side of the rotation curve flattens but the other side continues to rise. This
kinematic asymmetry is coupled with a dramatic asymmetry in the molecular gas
distribution but not in the atomic gas. An analysis of the gas column densities
and the interstellar pressure suggests that the H2/HI surface density ratio on
the east side of the galaxy is three times higher than expected from the
hydrostatic pressure contributed by the mass of the stellar disk. We discuss
the probable effects of ram pressure, gravitational interactions, and
asymmetric potentials on the interstellar medium and suggest it is likely that
a m=1 perturbation in the gravitational potential could be responsible for all
of the galaxy's features. Kinematic disturbances of the type seen here are
common, but the curious thing about NGC 4647 is that the molecular distribution
appears more disturbed than the HI distribution. Thus it is the combination of
the two gas phases that provides such interesting insight into the galaxy's
history and into models of the interstellar medium.


title: The Stellar Imager (SI) Vision Mission

abstract:
  The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer designed
to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of
the Universe in general and asteroseismic imaging of stellar interiors. SI is
identified as a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar
System Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life
Observatory" in the Exploration of the Universe Division (EUD) Roadmap (May,
2005). SI will revolutionize our view of many dynamic astrophysical processes:
its resolution will transform point sources into extended sources, and
snapshots into evolving views. SI's science focuses on the role of magnetism in
the Universe, particularly on magnetic activity on the surfaces of stars like
the Sun. SI's prime goal is to enable long-term forecasting of solar activity
and the space weather that it drives. SI will also revolutionize our
understanding of the formation of planetary systems, of the habitability and
climatology of distant planets, and of many magneto-hydrodynamically controlled
processes in the Universe. The results of the SI "Vision Mission" Study are
presented in this paper. Additional information on the SI mission concept and
related technology development can be found at URL:
http://hires.gsfc.nasa.gov/si/.


title:
Non-Equilibrium Beta Processes in Neutron Stars: A Relationship between
  the Net Reaction Rate and the Total Emissivity of Neutrinos

abstract:
  Several different processes could be changing the density in the core of a
neutron star, leading to a departure from $\beta$ equilibrium, quantified by
the chemical potential difference $\delta\mu\equiv\mu_n-\mu_p-\mu_e$. The
evolution of this quantity is coupled to that of the star's interior
temperature $T$ by two functions that quantify the rate at which
neutrino-emitting reactions proceed: the net reaction rate (difference between
$\beta$ decay and capture rates), $\Gamma_{\rm net}(T,\delta\mu)$, and the
total emissivity (total energy emission rate in the form of neutrinos and
antineutrinos), $\epsilon_{\rm tot}(T,\delta\mu)$. Here, we present a simple
and general relationship between these variables, ${\partial\epsilon_{\rm
tot}/\partial\delta\mu=3\Gamma_{\rm net}}$, and show that it holds even in the
case of superfluid nucleons. This relation may simplify the numerical
calculation of these quantities, including superfluid reduction factors.


title:
High energy neutrino astronomy using upward-going muons in
  Super-Kamiokande-I

abstract:
  We present the results from several studies used to search for astrophysical
sources of high-energy neutrinos using the Super-Kamiokande-I (April 1996 to
July 2001) neutrino-induced upward-going muon data. The data set consists of
2359 events with minimum energy 1.6 GeV, of which 1892 are through-going and
467 stop within the detector. The results of several independent analyses are
presented, including searches for point sources using directional and temporal
information and a search for signatures of cosmic-ray interactions with the
interstellar medium in the upward-going muons. No statistically significant
evidence for point sources or any diffuse flux from the plane of the galaxy was
found, so specific limits on fluxes from likely point sources are calculated.
The 90% C.L. upper limits on upward-going muon flux from astronomical sources
which are located in the southern hemisphere and always under the horizon for
Super-Kamiokande are 1~4x10^{-15} cm^{-2} s^{-1}.


title:
Chandra Observations of Galactic Center: High Energy Processes at
  Arcsecond Resolution

abstract:
  About 2 million seconds of Chandra observing time have been devoted to the
Galactic center (GC), including large-scale surveys and deep pointings. These
observations have led to the detection of about 4000 discrete X-ray sources and
the mapping of diffuse X-ray emission in various energy bands. In this review,
I first summarize general results from recent studies and then present close-up
views of the three massive star clusters (Arches, Quintuplet, and GC) and their
interplay with the Galactic nuclear environment.


title: The alignment of dark matter halos with the cosmic web

abstract:
  We investigate the orientation of the axes and angular momentum of dark
matter halos with respect to their neighboring voids using high resolution
N-body cosmological simulations. We find that the minor axis of halos tends to
be aligned along the line joining the halo with the center of the void, and
that the major axis is perpendicular to this line. However, we find that the
angular momentum of halos does not have any particular orientation. These
results may provide information about the mechanisms whereby the large-scale
structure of the Universe affects galaxy formation and cast light upon the
issue of the orientation of galaxy disks with respect to their host halos.


title: Probing dark energy with the shear-ratio geometric test

abstract:
  We adapt the Jain--Taylor (2003) shear-ratio geometric lensing method to
measure the dark energy equation of state, and its time derivative from dark
matter haloes in cosmologies with arbitrary spatial curvature. The full
shear-ratio covariance matrix is calculated for lensed sources, including the
intervening large-scale structure and photometric redshift errors as additional
sources of noise, and a maximum likelihood method for applying the test is
presented. Combining with the expected results from the CMB we design an
optimal survey for probing dark energy. A targeted survey imaging 60 of the
largest clusters in a hemisphere with 5-band optical photometric redshifts to a
median galaxy depth of zm=0.9 could measure w0 to a marginal 1-sigma error of
$\Delta$w0=0.5. We marginalize over all other parameters including wa, where
the equation of state is parameterized in terms of scale factor a as
w(a)=w0+wa(1-a). For higher accuracy a large-scale photometric redshift survey
is required. Such a near-future 5-band survey covering 10,000 square degrees to
z_m=0.7 could measure w0 to $\Delta$w0=0.075 and $\Delta$wa=0.33. A stronger
combined constraint is measured at a pivot redshift zp=0.27 of
$\Delta$w(zp)=0.0298. We compare and combine the geometric test with the
cosmological and dark energy parameters measured from planned Baryon Acoustic
Oscillation (BAO) and supernova Type Ia experiments, and find that the
geometric test results combine with a significant reduction in errors due to
different degeneracies. A combination of geometric lensing, CMB and BAO
experiments could achieve a pivot redshift constraint of $\Delta$w(zp)=0.020 at
zp=0.62. Simple relations are presented that show how our lensing results can
be scaled to other telescope classes and survey parameters.


title: Chandra Observations of Red Sloan Digital Sky Survey Quasars

abstract:
  We present short \chandra observations of twelve bright (i<18) z_em~1.5
quasars from the Sloan Digital Sky Survey chosen to have significantly redder
optical colors than most quasars at the same redshift. Of the five quasars with
optical properties most consistent with dust reddening at the quasar redshift,
four show indirect evidence of moderate X-ray absorption (inferred N_H~10^22
cm^-2) with a dust-to-gas ratio <1% of the SMC value. The remaining seven
objects show no evidence for even moderate intrinsic X-ray absorption. Thus,
while optically red quasars are marginally more likely to show signatures of
X-ray absorption than optically selected quasars with normal colors,
dust-reddened type 1 AGN (as opposed to fully obscured type 2 AGN) are unlikely
to contribute significantly to the remaining unresolved hard X-ray background.
The red quasar population includes objects with intrinsically red continua as
well as objects with dust-reddened continua. Improved sample selection is thus
needed to increase our understanding of either subpopulation. To identify
dust-reddened quasars likely to exhibit X-ray absorption, some measure of
spectral curvature is preferable to simple cuts in observed or relative
broad-band colors.


title:
A weak lensing estimate from GEMS of the virial to stellar mass ratio in
  massive galaxies to z~0.8

abstract:
  We present constraints on the evolution of the virial to stellar mass ratio
of galaxies with high stellar masses in the redshift range 0.2<z<0.8, by
comparing weak lensing measurements of virial mass M_vir to estimates of
stellar mass M_star from COMBO-17. For a complete sample of galaxies with
log(M_star/ M_\odot) > 10.5, where the majority show an early-type morphology,
we find that the virial mass to stellar mass ratio is given by M_vir/M_star =
53^{+13}_{-16}. Assuming a baryon fraction from the concordance cosmology, this
corresponds to a stellar fraction of baryons in massive galaxies of
Omega_b^*/\Omega_b = 0.10 +/- 0.03. Analysing the galaxy sample in different
redshift slices, we find little or no evolution in the virial to stellar mass
ratio, and place an upper limit of ~2.5 on the growth of massive galaxies
through the conversion of gas into stars from z=0.8 to the present day.


title: A Genuine Intermediate-Age Globular Cluster in M33

abstract:
  We present deep integrated-light spectroscopy of nine M33 globular clusters
taken with the Hectospec instrument at the MMT Observatory. Based on our
spectroscopy and previous deep color-magnitude diagrams obtained with
HST/WFPC2, we present evidence for the presence of a genuine intermediate-age
globular cluster in M33. The analysis of Lick line indices indicates that all
globular clusters are metal-poor ([Z/H] <~ -1.0) and that cluster M33-C38 is
about 5-8 Gyr younger than the rest of the sample M33 star clusters. We find no
evidence for a population of blue horizontal branch stars in the CMD of
M33-C38, which rules out the possibility of an artificially young spectroscopic
age due to the presence of hot stars. We infer a total mass of 5-9 x 10^4 M_sol
for M33-C38, which implies that M33-C38 has survived ~2-3 times longer than
some dynamical evolution model predictions for star clusters in M33, although
it is not yet clear to which dynamical component of M33 - thin disk, thick
disk, halo - the cluster is associated.


title:
The Anisotropy in the Galaxy Velocity Field Originated from the
  Gravitational Pancaking Effect

abstract:
  We analyze the Millennium run semi-analytic galaxy catalog to explore
quantitatively the gravitational pancaking effect on the orientation of galaxy
velocity field. We first calculate the probability density distribution of the
cosine of the angle between the velocity of a field galaxy and the direction
normal to a local pancake plane which is determined using two nearest neighbor
field galaxies. A clear signal of alignment is detected for the case that the
pancake scale is in the range of $5-8h^{-1}$ Mpc. The tendency of the
velocity-pancake alignment is found to still exist when the pancakes are
determined using three neighbor galaxies, indicating that it has a spatial
coherence. The degree of the velocity-pancake alignment is shown to increase
with the velocity magnitude and the local density, while it decreases with the
separation distance from the galaxy to the pancake and disappears when the
pancake has a filamentary shape. A final conclusion is that our work may
provide another clue to understanding the large-scale structure in the
universe.


title:
Inverse Compton e-p pair cascade model for the gamma-ray production in
  massive binary LSI +61^o 303

abstract:
  We apply an inverse Compton $e^\pm$ pair cascade model for $\gamma$-ray
production in massive binary system LSI +61$^{\rm o}$ 303 assuming that
electrons are accelerated already inside the inner part of the jet launched by
the compact object. $\gamma$-ray spectra, affected by the cascade process, and
lower energy spectra, from the synchrotron cooling of the highest energy
electrons in the jet, are calculated as a function of the phase of this binary
system. $\gamma$-ray spectra expected in such model have different shape than
that ones produced by electrons in the jet directly to observer. Moreover, the
model predicts clear anti-correlation between $\gamma$-ray fluxes in the GeV
(1-10 GeV) and TeV ($>200$ GeV) energy ranges with the peak of the TeV emission
at the phase $\sim$0.5 (the peak half width ranges between the phases
$\sim$0.4-0.9 for the inclination of the binary system equal to $60^{\rm o}$,
and $\sim$0.4-0.1 for $30^{\rm o}$). The fine features of TeV $\gamma$-ray
emission (fluxes and spectral shapes) as a function of the phase of the binary
system are consistent with recent observations reported by the MAGIC
collaboration. Future simultaneous observations in the GeV energies (by the
GLAST and AGILE telescopes) and in the TeV energies (by the MAGIC and VERITAS
telescopes) should test other predictions of the considered model supporting or
disproving the hypothersis of acceleration of electrons already in the inner
part of the microquasar jets.


title:
CO(1-0) in z >/~ 4 Quasar Host Galaxies: No Evidence for Extended
  Molecular Gas Reservoirs

abstract:
  We present CO(1-0) observations of the high-redshift quasi-stellar objects
(QSOs) BR 1202-0725 (z=4.69), PSS J2322+1944 (z=4.12), and APM 08279+5255
(z=3.91) using the NRAO Green Bank Telescope (GBT) and the MPIfR Effelsberg
100m telescope. We detect, for the first time, the CO ground-level transition
in BR 1202-0725. For PSS J2322+1944 and APM 08279+5255, our observations result
in line fluxes that are consistent with previous NRAO Very Large Array (VLA)
observations, but they reveal the full line profiles. We report a typical
lensing-corrected velocity-integrated intrinsic CO(1-0) line luminosity of
L'(CO) = 5 x 10^10 K km/s pc^2 and a typical total H_2 mass of M(H2) = 4 x
10^10 M_sun for the sources in our sample. The CO/FIR luminosity ratios of
these high-z sources follow the same trend as seen for low-z galaxies, leading
to a combined solution of log(L_FIR) = (1.39 +/- 0.05) x log(L(CO))-1.76. It
has previously been suggested that the molecular gas reservoirs in some quasar
host galaxies may exhibit luminous, extended CO(1-0) components that are not
observed in the higher-J CO transitions. Utilizing the line profiles and the
total intensities of our observations and large velocity gradient (LVG) models
based on previous results for higher-J CO transitions, we derive that emission
from all CO transitions is described well by a single gas component where all
molecular gas is concentrated in a compact nuclear region. Thus, our
observations and models show no indication of a luminous extended, low surface
brightness molecular gas component in any of the high-redshift QSOs in our
sample. If such extended components exist, their contribution to the overall
luminosity is limited to at most 30%.


title:
Anisotropic Galactic Outflows and Enrichment of the Intergalactic
  Medium. I: Monte Carlo Simulations

abstract:
  We have developed an analytical model to describe the evolution of
anisotropic galactic outflows. With it, we investigate the impact of varying
opening angle on galaxy formation and the evolution of the IGM. We have
implemented this model in a Monte Carlo algorithm to simulate galaxy formation
and outflows in a cosmological context. Using this algorithm, we have simulated
the evolution of a comoving volume of size [12h^(-1)Mpc]^3 in the LCDM
universe. Starting from a Gaussian density field at redshift z=24, we follow
the formation of ~20,000 galaxies, and simulate the galactic outflows produced
by these galaxies. When these outflows collide with density peaks, ram pressure
stripping of the gas inside the peak may result. This occurs in around half the
cases and prevents the formation of galaxies. Anisotropic outflows follow the
path of least resistance, and thus travel preferentially into low-density
regions, away from cosmological structures (filaments and pancakes) where
galaxies form. As a result, the number of collisions is reduced, leading to the
formation of a larger number of galaxies. Anisotropic outflows can
significantly enrich low-density systems with metals. Conversely, the
cross-pollution in metals of objects located in a common cosmological
structure, like a filament, is significantly reduced. Highly anisotropic
outflows can travel across cosmological voids and deposit metals in other,
unrelated cosmological structures.


title: The Spectropolarimetric Evolution of V838 Monocerotis

abstract:
  I review photo-polarimetric and spectropolarimetric observations of V838 Mon,
which revealed that it had an asymmetrical inner circumstellar envelope
following its 2nd photometric outburst. Electron scattering, modified by pre-
or post-scattering H absorption, is the polarizing mechanism in V838 Mon's
envelope. The simplest geometry implied by these observations is that of a
spheroidal shell, flattened by at least 10% and having a projected position
angle on the sky of $\sim37^{\circ}$. Analysis of V838 Mon's polarized flux
reveals that this electron scattering shell lies interior to the envelope
region in which H$\alpha$ and Ca II triplet emission originates. To date, none
of the theoretical models proposed for V838 Mon have demonstrated that they can
reproduce the evolution of V838 Mon's inner circumstellar environment, as
probed by spectropolarimetry.


title:
Temporal Evolution of Pair Attenuation Signatures in Gamma-Ray Burst
  Spectra

abstract:
  The spectra obtained above 100 MeV by the EGRET experiment aboard the Compton
Gamma-Ray Observatory for a handful of gamma-ray bursts has given no indication
of any spectral attenuation that might preclude detection of bursts at higher
energies. With the discovery of optical afterglows and counterparts to bursts
in the last few years, enabling the determination of significant redshifts for
these sources, it is anticipated that profound spectral attenuation will arise
in the Gamma-Ray Large Area Space Telescope (GLAST) energy band of 30 MeV-300
GeV for many if not most bursts. This paper explores time-dependent
expectations for burst spectral properties in the EGRET/GLAST band, focusing on
how attenuation of photons by pair creation internal to the source generates
distinctive spectral signatures. The energy of spectral breaks and the
associated spectral indices provide valuable information that constrains the
bulk Lorentz factor of the GRB outflow at a given time. Moreover, the distinct
temporal behavior that is present for internal attenuation is easily
distinguished from extrinsic absorption due to intervening cosmic background
fields. These characteristics define palpable observational goals for both
spaced-based hard gamma-ray experiments such as GLAST, and ground-based
Cherenkov telescopes, and strongly impact the observability of bursts above 300
MeV.


title: Long-term Variability in the Length of the Solar Cycle

abstract:
  Detailed models of the solar cycle require information about the starting
time and rise time as well as the shape and amplitude of the cycle. However,
none of these models includes a discussion of the variations in the length of
the cycle, which has been known to vary from $\sim$7 to 17 years. The focus of
our study was to investigate whether this range was associated with a secular
pattern in the length of the sunspot cycle. To provide a basis for the analysis
of the long-term behavior of the Sun, we analyzed archival data of sunspot
numbers from 1700 - 2005 and sunspot areas from 1874 - 2005. The independent
techniques of power spectrum analysis and phase dispersion minimization were
used to confirm the $\sim$11-year Schwabe Cycle, and to illustrate the large
range in the length of this cycle. Long-term cycles were identified in archival
data from 1610 -- 2000 using median trace analyses of the length of the cycle,
and from power spectrum analyses of the (O-C) residuals of the dates of sunspot
minima and maxima. The median trace analysis suggested that the cycle length
had a period of 183 - 243 years, while the more precise power spectrum analysis
identified a period of 188 $\pm$ 38 years. We found that the 188-year cycle was
consistent with the variation of sunspot numbers and seems to be related to the
Schwabe Cycle. We found a correlation between the times of historic minima and
the length of the sunspot cycle such that the length of the cycle was usually
highest when the actual number of sunspots was lowest. The cycle length was
growing during the Maunder Minimum when there were almost no sunspots visible
on the Sun. This information can now be used to improve the accuracy of the
current solar cycle models, to better predict the starting time of a given
cycle.


title: Capture Rates of Compact Objects by Supermassive Black Holes

abstract:
  Capture rates of compact objects were calculated by using a recent solution
of the Fokker-Planck equation in energy-space, including two-body resonant
effects. The fraction of compact objects (white dwarfs, neutron stars and
stellar black holes) was estimated as a function of the luminosity of the
galaxy from a new grid of evolutionary models. Stellar mass densities at the
influence radius of central supermassive black holes were derived from
brightness profiles obtained by Hubble Space Telescope observations. The
present study indicates that the capture rates scale as $\propto
M_{bh}^{-1.048}$, consequence of the fact that dwarf galaxies have denser
central regions than luminous objects. If the mass distribution of supermassive
black holes has a lower cutoff at $\sim 1.4\times 10^6$ M$_{\odot}$
(corresponding to the lowest observed supermassive black hole mass, located in
M32), then 9 inspiral events are expected to be seen by LISA (7-8 corresponding
to white dwarf captures and 1-2 to neutron star and stellar black hole
captures) after one year of operation. However, if the mass distribution
extends down to $\sim 2\times 10^5$ M$_{\odot}$, then the total number of
expected events increases up to 579 (corresponding to $\sim$ 274 stellar black
hole captures, $\sim$ 194 neutron star captures and $\sim$ 111 white dwarf
captures).


title:
The Variability and Rotation of Pre-main Sequence Stars in IC 348: Does
  Intracluster Environment Influence Stellar Rotation?

abstract:
  A variability study of the young cluster IC 348 at Van Vleck Observatory has
been extended to a total of seven years. Twelve new periodic stars have been
found in the last two years, bringing the total discovered by this program to
40. In addition, we confirm 16 of the periods reported by others and resolve
some discrepancies. The total number of known rotation periods in the cluster,
from all studies has now reached 70. This is sufficient to demonstrate that the
parent population of K5-M2 stars is rotationally indistinguishable from that in
the Orion Nebula Cluster even though their radii are 20% smaller and they would
be expected to spin about twice as fast if angular momentum were conserved. The
median radius and, therefore, inferred age of the IC 348 stars actually closely
matches that of NGC 2264, but the stars spin significantly more slowly. This
suggests that another factor besides mass and age plays a role in establishing
the rotation properties within a cluster and we suggest that it is environment.
If disk locking were to persist for longer times in less harsh environments,
because the disks themselves persist for longer times, it could explain the
generally slower rotation rates observed for stars in this cluster, whose
earliest type star is of class B5. We have also obtained radial velocities, the
first for PMS stars in IC348, and v sin i measurements for 30 cluster stars to
assist in the study of rotation and as an independent check on stellar radii.
Several unusual variable stars are discussed; in some or all cases their
behavior may be linked to occultations by circumstellar material. A strong
correlation exists between the range of photometric variability and the slope
of the spectral energy distribution in the infrared. Nineteen of the 21 stars
with I ranges exceeding 0.4 mag show infrared evidence for circumstellar disks.


title: Difficulties for Compact Composite Object Dark Matter

abstract:
  It has been suggested ``that DM particles are strongly interacting composite
macroscopically large objects ... made of well known light quarks (or ...
antiquarks)." In doing so it is argued that these compact composite objects
(CCOs) are ``natural explanations of many observed data, such as [the] 511 keV
line from the bulge of our galaxy" observed by INTEGRAL and the excess of
diffuse gamma-rays in the 1-20 MeV band observed by COMPTEL. Here we argue that
the atmospheres of positrons that surround CCOs composed of di-antiquark pairs
in the favoured Colour-Flavour-Locked superconducting state are sufficiently
dense as to stringently limit the penetration of interstellar electrons
incident upon them, resulting in an extreme suppression of previously estimated
rates of positronium, and hence the flux of 511 keV photons resulting from
their decays, and also in the rate of direct electron-positron annihilations,
which yield the MeV photons proposed to explain the 1-20 MeV excess. We also
demonstrate that even if a fraction of positrons somehow penetrated to the
surface of the CCOs, the extremely strong electric fields generated from the
bulk antiquark matter would result in the destruction of positronium atoms long
before they decay.


title:
On Predicting the Polarization of Low Frequency Emission by Diffuse
  Interstellar Dust

abstract:
  Several of the current and next-generation cosmic microwave background (CMB)
experiments have polarimetric capability, promising to add to the finesse of
precision cosmology. One of the contaminating Galactic foregrounds is thermal
emission by dust. Since optical interstellar polarization is commonly seen,
from differential extinction by aligned aspherical dust particles, it is
expected that thermal emission from these grains will be polarized. Indeed, in
the Galactic plane and in dark (molecular) clouds, dust emission in the
infrared and submillimetre has been measured to be polarized. It seems likely
that the faint diffuse cirrus emission, of more relevance to CMB experiments,
will be polarized too. We discuss how well the amount of polarization of this
component can be predicted, making use of what is known about optical (and
infrared and ultraviolet) interstellar polarization and extinction. Some
constraints on the alignment of the carrier of the dust-correlated anomalous
microwave emission can be made as well.


title:
A model-independent dark energy reconstruction scheme using the
  geometrical form of the luminosity-distance relation

abstract:
  We put forward a new model-independent reconstruction scheme for dark energy
which utilises the expected geometrical features of the luminosity-distance
relation. The important advantage of this scheme is that it does not assume
explicit ansatzes for cosmological parameters but only some very general
cosmological properties via the geometrical features of the reconstructed
luminosity-distance relation. Using the recently released supernovae data by
the Supernova Legacy Survey together with a phase space representation, we show
that the reconstructed luminosity-distance curves best fitting the data
correspond to a slightly varying dark energy density with the Universe
expanding slightly slower than the Lambda CDM model. However, the Lambda CDM
model fits the data at 1 sigma significance level and the fact that our best
fitting luminosity-distance curve is lower than that of the corresponding
Lambda CDM model could be due to systematics. The transition from an
accelerating to a decelerating expansion occurs at a redshift larger than
z=0.35. Interpreting the dark energy as a minimally coupled scalar field we
also reconstruct the scalar field and its potential. We constrain
$\Omega_{m_0}$ using the baryon acoustic oscillation peak in the SDSS luminous
red galaxy sample and find that the best fit is obtained with
$\Omega_{m_0}=0.27$, in agreement with the CMB data.


title: Spitzer/IRAC Photometry of M, L, and T Dwarfs

abstract:
  We present the results of a program to acquire photometry for eighty-six
late-M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer
Space Telescope. We examine the behavior of these cool dwarfs in various
color-color and color-magnitude diagrams composed of near-IR and IRAC data. The
T dwarfs exhibit the most distinctive positions in these diagrams. In M_5.8
versus [5.8]-[8.0], the IRAC data for T dwarfs are not monotonic in either
magnitude or color, giving the clearest indication yet that the T dwarfs are
not a one parameter family in Teff. Because metallicity does not vary enough in
the solar neighborhood to act as the second parameter, the most likely
candidate then is gravity, which in turn translates to mass. Among objects with
similar spectral type, the range of mass suggested by our sample is about a
factor of five (~70 M_Jup to ~15 M_Jup), with the less massive objects making
up the younger members of the sample. We also find the IRAC 4.5 micron fluxes
to be lower than expected, from which we infer a stronger CO fundamental band
at ~4.67 microns. This suggests that equilibrium CH_4/CO chemistry
underestimates the abundance of CO in T dwarf atmospheres, confirming earlier
results based on M-band observations from the ground. In combining IRAC
photometry with near-IR JHK photometry and parallax data, we find the
combination of Ks, IRAC 3.6 micron, and 4.5 micron bands to provide the best
color-color discrimination for a wide range of M, L, and T dwarfs. Also
noteworthy is the M_Ks versus Ks-[4.5] relation, which shows a smooth
progression over spectral type and splits the M, L, and T types cleanly.


title: Nonlinear Diffusive Shock Acceleration with Magnetic Field Amplification

abstract:
  We introduce a Monte Carlo model of nonlinear diffusive shock acceleration
allowing for the generation of large-amplitude magnetic turbulence. The model
is the first to include strong wave generation, efficient particle acceleration
to relativistic energies in nonrelativistic shocks, and thermal particle
injection in an internally self-consistent manner. We find that the upstream
magnetic field can be amplified by large factors and show that this
amplification depends strongly on the ambient Alfven Mach number. We also show
that in the nonlinear model large increases in the magnetic field do not
necessarily translate into a large increase in the maximum particle momentum a
particular shock can produce, a consequence of high momentum particles
diffusing in the shock precursor where the large amplified field converges to
the low ambient value. To deal with the field growth rate in the regime of
strong fluctuations, we extend to strong turbulence a parameterization that is
consistent with the resonant quasi-linear growth rate in the weak turbulence
limit. We believe our parameterization spans the maximum and minimum range of
the fluctuation growth and, within these limits, we show that the nonlinear
shock structure, acceleration efficiency, and thermal particle injection rates
depend strongly on the yet to be determined details of wave growth in strongly
turbulent fields. The most direct application of our results will be to
estimate magnetic fields amplified by strong cosmic-ray modified shocks in
supernova remnants.


title: Migration of dust particles to the terrestrial planets

abstract:
  The orbital evolution of asteroidal, trans-Neptunian, and cometary dust
particles under the gravitational influence of planets, the Poynting-Robertson
drag, radiation pressure, and solar wind drag was integrated. Results of our
runs were compared with the spacecraft observations of the number density of
dust particles and with the WHAM observations of velocities of zodiacal
particles. This comparison shows that the fraction of cometary dust particles
of the overall dust population inside Saturn's orbit is significant and can be
dominant. The probability of a collision of an asteroidal or cometary dust
particle with the Earth during its dynamical lifetime is maximum at diameter
about 100 micron.


title:
Thermal evolution of the primordial clouds in warm dark matter models
  with keV sterile neutrinos

abstract:
  We analyze the processes relevant for star formation in a model with dark
matter in the form of sterile neutrinos. Sterile neutrino decays produce an
X-ray background radiation that has a two-fold effect on the collapsing clouds
of hydrogen. First, the X-rays ionize the gas and cause an increase in the
fraction of molecular hydrogen, which makes it easier for the gas to cool and
to form stars. Second, the same X-rays deposit a certain amount of heat, which
could, in principle, thwart the cooling of gas. We find that, in all the cases
we have examined, the overall effect of sterile dark matter is to facilitate
the cooling of gas. Hence, we conclude that dark matter in the form of sterile
neutrinos can help the early collapse of gas clouds and the subsequent star
formation.


title:
A study on the use of the PACS bolometer arrays for submillimeter
  ground-based telescopes

abstract:
  A new kind of bolometric architecture has been successfully developed for the
PACS photometer onboard the Herschel submillimeter observatory. These new
generation CCD-like arrays are buttable and enable the conception of large
fully sampled focal planes. We present a feasibility study of the adaptation of
these bolometer arrays to ground-based submillimeter telescopes. We have
developed an electro-thermal numerical model to simulate the performances of
the bolometers under specific ground-based conditions (different wavelengths
and background powers for example). This simulation permits to determine the
optimal parameters for each condition and shows that the bolometers can be
background limited in each transmission window between 200 and 450 microns. We
also present a new optical system that enables to have a maximum absorption of
the bolometer in each atmospheric windows. The description of this system and
measurements are showed.


title:
Cosmological production of H_2 before the formation of the first
  galaxies

abstract:
  Previous calculations of the pregalactic chemistry have found that a small
amount of H_2, x[H_2]=n[H_2]/n[H] = 2.6e-6, is produced catalytically through
the H^-, H_2^+, and HeH^+ mechanisms. We revisit this standard calculation
taking into account the effects of the nonthermal radiation background produced
by cosmic hydrogen recombination, which is particularly effective at destroying
H^- via photodetachment. We also take into consideration the non-equilibrium
level populations of H_2^+, which occur since transitions among the
rotational-vibrational levels are slow compared to photodissociation. The new
calculation predicts a final H_2 abundance of x[H_2] = 6e-7 for the standard
cosmology. This production is due almost entirely to the H^- mechanism, with ~1
per cent coming from HeH^+ and ~0.004 per cent from H_2^+. We evaluate the
heating of the diffuse pregalactic gas from the chemical reactions that produce
H_2 and from rotational transitions in H_2, and find them to be negligible.


title:
XMM and Chandra measurements of the AGN intrinsic absorption: dependence
  on luminosity and redshift

abstract:
  We combine bright XMM data with the Chandra Deep Field South observations in
order to explore the behavior of the intrinsic AGN absorption, as a function of
redshift and luminosity.Our sample consists of 359 sources selected in the hard
2-8 keV band, spanning the flux range 6\times10^{-16}-$3\times10^{-13} erg s^-1
cm^-2 with a high rate of spectroscopic or photometric redshift completeness
(100 and 85 per cent respectively for the Chandra and XMM data. We derive the
column density values using X-ray spectral fits. We find that the fraction of
obscured AGN falls with increasing luminosity in agreement with previous
findings. The fraction of obscured AGN shows an apparent increase at high
redshifts (z>2). Simulations show that this effect can be most probably
attributed to the fact that at high redshifts the column densities are
overestimated.


title: Deep and wide field imaging of the Coma cluster: the data

abstract:
  We have obtained deep and wide field imaging of the Coma cluster of galaxies
with the CFH12K camera at CFHT in the B, V, R and I filters. In this paper, we
present the observations, data reduction, catalogs and first scientific
results.
  We investigated the quality of our data by internal and external literature
comparisons. We also checked the realisation of the observational requirements
we set.
  Our observations cover two partially overlapping areas of $42 \times 28$
arcmin$^2$, leading to a total area of 0.72 $\times$ 0.82 deg$^2$. We have
produced catalogs of objects that cover a range of more than 10 magnitudes and
are complete at the 90% level at B$\sim$25, V$\sim$24, R$\sim$24 and
I$\sim$23.5 for stellar-like objects, and at B$\sim$22, V$\sim$21, R$\sim$20.75
and I$\sim$20.5 for faint low-surface-brightness galaxy-like objects.
Magnitudes are in good agreement with published values from R$\sim$16 to
R$\sim$25. The photometric uncertainties are of the order of 0.1 magnitude at
R$\sim$20 and of 0.3 magnitude at R$\sim$25. Astrometry is accurate to
0.5~arcsec and also in good agreement with published data.
  Our catalog provides a rich dataset that can be mined for years to come to
gain new insights into the formation and evolution of the Coma cluster and its
galaxy population. As an illustration of the data quality, we examine the
bright part of the Colour Magnitude Relation (B-R versus R) derived from the
catalog and find that it is in excellent agreement with that derived for
galaxies with redshifts in the Coma cluster, and with previous CMRs estimated
in the literature.


title: The GALEX Ultraviolet Atlas of Nearby Galaxies

abstract:
  We present images, integrated photometry, surface-brightness and color
profiles for a total of 1034 nearby galaxies recently observed by the GALEX
satellite in its far-ultraviolet (FUV; 1516A) and near-ultraviolet (NUV; 2267A)
bands. (...) This data set has been complemented with archival optical,
near-infrared, and far-infrared fluxes and colors. We find that the integrated
(FUV-K) color provides robust discrimination between elliptical and
spiral/irregular galaxies and also among spiral galaxies of different
sub-types. Elliptical galaxies with brighter K-band luminosities (i.e. more
massive) are redder in (NUV-K) color but bluer in (FUV-NUV) than less massive
ellipticals. In the case of the spiral/irregular galaxies our analysis shows
the presence of a relatively tight correlation between the (FUV-NUV) color and
the total infrared-to-UV ratio. The correlation found between (FUV-NUV) color
and K-band luminosity (with lower luminosity objects being bluer than more
luminous ones) can be explained as due to an increase in the dust content with
galaxy luminosity.
  The images in this Atlas along with the profiles and integrated properties
are publicly available through a dedicated web page at
http://nedwww.ipac.caltech.edu/level5/GALEX_Atlas/


title: Flares in GRB afterglows from delayed magnetic dissipation

abstract:
  One of the most intriguing discoveries made by the Swift satellite is the
flaring activity in about half of the afterglow lightcurves. Flares have been
observed on both long and short duration GRBs and on time scales that range
from minutes to ~1 day after the prompt emission. The rapid evolution of some
flares led to the suggestion that they are caused by late central engine
activity. Here, I propose an alternative explanation that does not need
reviving of the central engine. Flares can be powered by delayed magnetic
dissipation in strongly magnetized (i.e. with initial Poynting to kinetic flux
ratio $\simmore 1$) ejecta during its deceleration due to interaction with the
external medium. A closer look at the length scales of the dissipation regions
shows that magnetic dissipation can give rise to fast evolving and energetic
flares. Multiple flares are also expected in the context of the model.


title:
Towards event-by-event studies of the ultrahigh-energy cosmic-ray
  composition

abstract:
  We suggest a method which improves the precision of studies of the primary
composition of ultra-high-energy cosmic rays. Two principal ingredients of the
method are (1) comparison of the observed and simulated parameters for
individual showers, without averaging over arrival directions and (2)
event-by-event selection of simulated showers by the physical observables and
not by the reconstructed primary parameters. A detailed description of the
algorithm is presented and illustrated by several examples.


title: Massive perturber-driven interactions of stars with a massive black hole

abstract:
  We study the role of massive perturbers (MPs) in deflecting stars and
binaries to almost radial ("loss-cone") orbits, where they pass near the
central massive black hole (MBH), interact with it at periapse, and are
ultimately destroyed. MPs dominate dynamical relaxation when the ratio of the
2nd moments of the MP and star mass distributions,
mu_2=(N_p*<M_p^2>)/(N_s*<M_s^2>), satisfies mu_2>>1. We compile the MP mass
function from published observations, and show that MPs in the nucleus of the
Galaxy (mainly giant molecular clouds), and plausibly in late type galaxies
generally, have 10^2<mu_2<10^8. MPs thus shorten the relaxation timescale by
10^1-10^7 relative to 2-body relaxation by stars alone. We show this increases
by 10-1000 the rate of \emph{large}-periapse interactions with the MBH, where
loss-cone refilling by stellar 2-body relaxation is inefficient. We extend the
Fokker-Planck loss-cone formalism to approximately account for relaxation by
rare encounters with MPs. We show that binary stars--MBH exchanges driven by
MPs can explain the origin of the young main sequence B stars that are observed
very near the Galactic MBH, and increase by orders of magnitude the ejection
rate of hyper-velocity stars. In contrast, the rate of \emph{small}-periapse
interactions of single stars with the MBH, such as tidal disruption, is only
increased by a factor of a few. We suggest that MP-driven relaxation plays an
important role in the 3-body exchange capture of single stars on very tight
orbits around the MBH. These captured stars may later be disrupted by the MBH
via tidal orbital decay or direct scattering into the loss cone; captured
compact objects may inspiral into the MBH by the emission of gravitational
waves from zero-eccentricity orbits.


title: Dust in starburst nuclei and ULIRGs: SED models for observers

abstract:
  We provide a library of some 7000 SEDs (available at www.eso.org/~rsiebenm)
for the nuclei of starburst and ultra luminous galaxies. Its purpose is to
quickly obtain estimates of the basic parameters, such as luminosity, size and
dust or gas mass and to predict the flux at yet unobserved wavelengths. The
procedure is simple and consists of finding an element in the library that
matches the observations. The objects may be in the local universe or at high
z.
  We calculate the radiative transfer in spherical symmetry for a stellar
cluster permeated by an interstellar medium with standard (Milky Way) dust
properties. The cluster contains two stellar populations: old bulge stars and
OB stars. Because the latter are young, a certain fraction of them will be
embedded in compact clouds which constitute hot spots that determine the MIR
fluxes.
  We present SEDs for a broad range of luminosities, sizes and obscurations. We
argue that the assumption of spherical symmetry and the neglect of clumpiness
of the medium are not severe shortcomings for computing the dust emission. The
validity of the approach is demonstrated by matching the SED of seven of the
best studied galaxies, including M82 and Arp220, by library elements. In all
cases, one finds an element which fits the observed SED very well, and the
parameters defining the element are in full accord with what is known about the
galaxy from detailed studies. We also compare our method of computing SEDs with
other techniques described in the literature.


title: [CI] 492 GHz mapping toward Cas A

abstract:
  We have mapped the [C I] emission at 492 GHz toward the supernova remnant Cas
A. We detect [C I] emission from the periphery of the diffuse Photon Dominated
Region (PDR) covering the disk of Cas A, as traced by the carbon recombination
lines, as well as from the denser PDRs associated with the molecular clouds
towards the south-east. [C I] emission is detected from both the Perseus and
Orion arm molecular clouds, with the -47 km s^-1 Perseus arm feature being
strong enough to be detected at all positions. We estimate the C/CO relative
abundance to be 0.2 at the position of the identified CO clouds and >1 for most
of the cloud. Here we show that the distribution of [C I] emitting regions
compared to the C+ region and molecular cloud is consistent with a scenario
involving PDRs. Using physical models for PDRs we constrain the physical
properties of the [C I] line-forming regions. We estimate the densities of the
[C I] emitting regions to be between 10^2 and 10^3 cm^-3. Based on rather high
volume filling factors (~50%) we conclude that [C I] emission mainly arises
from diffuse neutral gas in the Perseus arm.


title: Nickel Bubble Expansion in Type Ia Supernovae: Adiabatic Solutions

abstract:
  This paper presents hydrodynamical and radiation-hydrodynamical simulations
of the nickel bubble effect in Type Ia supernovae, comparison of results to
self-similar solutions, and application to observations of Type Ia supernova
remnants, with a particular emphasis on Tycho's SNR.


title: Galaxy Galaxy Lensing as a Probe of Galaxy Dark Matter Halos

abstract:
  Gravitational lensing has now become a popular tool to measure the mass
distribution of structures in the Universe on various scales. Here we focus on
the study of galaxy's scale dark matter halos with galaxy-galaxy lensing
techniques: observing the shapes of distant background galaxies which have been
lensed by foreground galaxies allows us to map the mass distribution of the
foreground galaxies. The lensing effect is small compared to the intrinsic
ellipticity distribution of galaxies, thus a statistical approach is needed to
derive some constraints on an average lens population. An advantage of this
method is that it provides a probe of the gravitational potential of the halos
of galaxies out to very large radii, where few classical methods are viable,
since dynamical and hydrodynamical tracers of the potential cannot be found at
this radii. We will begin by reviewing the detections of galaxy-galaxy lensing
obtained so far. Next we will present a maximum likelihood analysis of
simulated data we performed to evaluate the accuracy and robustness of
constraints that can be obtained on galaxy halo properties. Then we will apply
this method to study the properties of galaxies which stand in massive cluster
lenses at z~0.2. The main result of this work is to find dark matter halos of
cluster galaxies to be significantly more compact compared to dark matter halos
around field galaxies of equivalent luminosity, in agreement with early
galaxy-galaxy lensing studies and with theoretical expectations, in particular
with the tidal stripping scenario. We thus provide a strong confirmation of
tidal truncation from a homogeneous sample of galaxy clusters. Moreover, it is
the first time that cluster galaxies are probed successfully using
galaxy-galaxy lensing techniques from ground based data.


title:
Concerning the instantaneous mass and the extent of an expanding
  universe

abstract:
  In this article we want to answer the cosmologically relevant question what,
with some good semantic and physical reason, could be called the mass of an
infinitely extended, homogeneously matter-filled and expanding universe. To
answer this question we produce a space-like sum of instantaneous cosmic energy
depositions surrounding equally each spacepoint in the homogeneous universe. We
calculate the added-up instantaneous cosmic energy per volume around an
arbitrary space point in the expanding universe. To carry out this sum we use
as basic metrics an analogy to the inner Schwarzschild metric applied to stars,
but this time applied to the spacepoint-related universe. It is then shown that
this leads to the added-up proper energy within a sphere of a finite outer
critical radius defining the point-related infinity. As a surprise this radius
turns out to be reciprocal to the square root of the prevailing average cosmic
energy density. The equivalent mass of the universe can then also be calculated
and, by the expression which is obtained here, shows a scaling with this
critical radius of this universe, a virtue of the universe which was already
often called for in earlier works by E.Mach, H.Thirring and F.Hoyle and others.
This radius on the other hand can be shown to be nearly equal to the
Schwarzschild radius of the so-defined mass of the universe.


title: Secondary Maximum in the Near-Infrared Lightcurves of Type Ia Supernovae

abstract:
  We undertake a theoretical study of the near-infrared (NIR) lightcurves of
Type Ia supernovae (SNe Ia). In these bands, the lightcurves are distinguished
by a secondary maximum occurring roughly 20 to 30 days after the initial one.
Using time-dependent multi-group radiative transfer calculations, we calculate
the UBVRIJHK-band lightcurves of model SN Ia ejecta structures. Our synthetic
NIR lightcurves show distinct secondary maxima, and provide favorable fits to
observed SNe Ia. We offer a detailed explanation of the origin of the NIR
secondary maximum, which is shown to relate directly to the ionization
evolution of iron group elements in the ejecta. This understanding provides
immediate intuition into the dependence of the NIR lightcurves on the physical
properties of the ejecta, and in particular explains why brighter supernovae
have a later and more prominent secondary maximum. We demonstrate the
dependence of the NIR lightcurves on the mass of 56Ni, the degree of 56Ni
mixing, the mass of electron caputre elements, the progenitor metallicity, and
the abundance of intermediate mass elements (especially calcium). The secondary
maximum is shown to be a valuable diagnostic of these important physical
parameters. The models further confirm that SNe Ia should be excellent standard
candles in the NIR, with a dispersion < 0.2 mag even when the physical
properties of the ejecta are varied widely. This study emphasizes the
consummate value of NIR observations in probing the structure of SNe Ia and in
furthering their cosmological utility.


title: Supernova Fallback: A Possible Site for the r-Process

abstract:
  The conditions for the leading r-process site candidate, neutrino-driven
winds, can not be reproduced self-consistently in current supernova models. For
that reason, we investigate an alternate model involving the mass ejected by
fallback in a supernova explosion, through hydrodynamic and nucleosynthesis
calculations. The nucleosynthetic products of this ejected material produces
r-process elements, including those in the vicinity of the elusive 3rd peak at
mass number 195. Trans-iron element production beyond the second peak is made
possible by a rapid (<1ms) freezeout of alpha particles which leaves behind a
large nucleon (including protons!) to r-process seed ratio. This rapid phase is
followed by a relatively long (>15 ms) simmering phase at ~2e9 K, which is the
thermodynamic consequence of the hydrodynamic trajectory of the turbulent flows
in the fallback outburst. During the slow phase high mass elements beyond the
second peak are first made through rapid capture of both protons and neutrons.
The flow stays close to valley of stability during this phase. After freeze-out
of protons the remaining neutrons cause a shift out to short-lived isotopes as
is typical for the r-process. A low electron fraction isn't required in this
model, however, the detailed final distribution is sensitive to the electron
fraction. Our simulations suggest that supernova fallback is a viable
alternative scenario for the r-process.


title: Star cluster disruption by giant molecular clouds

abstract:
  We investigate encounters between giant molecular clouds (GMCs) and star
clusters. We propose a single expression for the energy gain of a cluster due
to an encounter with a GMC, valid for all encounter distances and GMC
properties. This relation is verified with N-body simulations of cluster-GMC
encounters and excellent agreement is found. The fractional mass loss from the
cluster is 0.25 times the fractional energy gain. This is because 75% of the
injected energy goes to the velocities of escaping stars, that are higher than
the escape velocity. We derive an expression for the cluster disruption time
(t_dis) based on the mass loss from the simulations, taking into account the
effect of gravitational focusing by the GMC. The disruption time depends on the
cluster mass (M_c) and half-mass radius (r_h) as t_dis=2.0 S (M_c/10^4
M_sun)(3.75 pc/r_h)^3 Gyr, with S=1 for the solar neighbourhood and inversely
proportional to the GMC density. The observed shallow relation between cluster
radius and mass gives t_dis a power-law dependence on the mass with index 0.7,
similar to that found from observations and from simulations of clusters
dissolving in tidal fields (0.62). The constant of 2.0 Gyr is about a factor of
3.5 shorter than found from earlier simulations of clusters dissolving under
the combined effect of galactic tidal field and stellar evolution. It is
somewhat higher than the observationally determined value of 1.3 Gyr. It
suggests, however, that the combined effect of tidal field and encounters with
GMCs can explain the lack of old open clusters in the solar neighbourhood. GMC
encounters can also explain the (very) short disruption time that was observed
for star clusters in the central region of M51, since there rho_n is an order
of magnitude higher than in the solar neighbourhood.


title: Inflation and WMAP three year data: Features have a Future!

abstract:
  The new three year WMAP data seem to confirm the presence of non-standard
large scale features in the Cosmic Microwave Anisotropies power spectrum. While
these features may hint at uncorrected experimental systematics, it is also
possible to generate, in a cosmological way, oscillations on large angular
scales by introducing a sharp step in the inflaton potential. Using current
cosmological data, we derive constraints on the position, magnitude and
gradient of a possible step. We show that a step in the inflaton potential,
while strongly constrained by current data, is still allowed and may provide an
interesting explanation to the currently measured deviations from the standard
featureless spectrum. Moreover, we show that inflationary oscillations in the
primordial power spectrum can significantly bias parameter estimates from
standard ruler methods involving measurements of baryon oscillations.


title:
A Spectroscopic Study of the Near-IR [SIII] Lines in a Sample of HII
  Galaxies: chemical abundances

abstract:
  A detailed spectroscopic study, from lambda 3700 A to 1 um, was performed for
a sample of 34 HII galaxies in order to derive fundamental parameters for their
HII regions and ionizing sources, as well as gaseous metal abundances. All the
spectra included the nebular [SIII]9069,9532 A lines, given their importance in
the derivation of the S/H abundance and relevant ionization diagnostics. A
systematic method was followed to correct the near-IR [SIII] line fluxes for
the effects of the atmospheric transmission.A comparative analysis of the
predictions of the empirical abundance indicators R23 and S23 has been
performed. The relative hardness of their ionizing sources was studied using
the eta parameter, and exploring the role played by metallicity. For 22
galaxies of the sample a direct value of te[SIII] was derived, along with their
ionic and total S/H abundances. Their ionic and total O/H abundances were
derived using direct determinations of te[OIII].For the rest of the objects,
the total S/H abundance was derived using S23. The abundance range covered by
our sample goes from 1/20 solar up to solar metallicity. The mean S/O ratio
derived is log (S/O)=-1.68+/-0.20 dex, 1 sigma below the solar S/O value. The
S/O abundance ratio shows no significant trend with O/H over the range of
abundance covered in this work, in agreement with previous findings.There is a
trend for HII galaxies with lower gaseous metallicity to present harder
ionizing spectra. We compared the distribution of the ionic ratios O+/O++ vs.
S+/S++ derived for our sample with the predictions of a grid of photoionization
models performed for different stellar effective temperatures. This analysis
indicates that a large fraction of galaxies in our sample seem to be ionized by
extremely hard spectra.


title: Mosaicking with cosmic microwave background interferometers

abstract:
  Measurements of cosmic microwave background (CMB) anisotropies by
interferometers offer several advantages over single-dish observations. The
formalism for analyzing interferometer CMB data is well developed in the
flat-sky approximation, valid for small fields of view. As the area of sky is
increased to obtain finer spectral resolution, this approximation needs to be
relaxed. We extend the formalism for CMB interferometry, including both
temperature and polarization, to mosaics of observations covering arbitrarily
large areas of the sky, with each individual pointing lying within the flat-sky
approximation. We present a method for computing the correlation between
visibilities with arbitrary pointing centers and baselines and illustrate the
effects of sky curvature on the l-space resolution that can be obtained from a
mosaic.


title:
[ArIII]/[OIII] and [SIII]/[OIII]: well-behaved oxygen abundance
  indicators for HII regions and star forming galaxies

abstract:
  We propose two statistical methods to derive oxygen abundances in HII regions
and star forming galaxies and calibrate them with a sample of several hundred
giant HII regions in spiral and blue compact galaxies as well as of galaxies
from the Sloan Digital Sky Survey. We show the advantages of our new abundance
indicators over previous ones.


title:
High Contrast L' Band Adaptive Optics Imaging to Detect Extrasolar
  Planets

abstract:
  We are carrying out a survey to search for giant extrasolar planets around
nearby, moderate-age stars in the mid-infrared L' and M bands (3.8 and 4.8
microns, respectively), using the Clio camera with the adaptive optics system
on the MMT telescope. To date we have observed 7 stars, of a total 50 planned,
including GJ 450 (distance about 8.55pc, age about 1 billion years, no real
companions detected), which we use as our example here. We report the methods
we use to obtain extremely high contrast imaging in L', and the performance we
have obtained. We find that the rotation of a celestial object over time with
respect to a telescope tracking it with an altazimuth mount can be a powerful
tool for subtracting telescope-related stellar halo artifacts and detecting
planets near bright stars. We have carried out a thorough Monte Carlo
simulation demonstrating our ability to detect planets as small as 6 Jupiter
masses around GJ 450. The division of a science data set into two independent
parts, with companions required to be detected on both in order to be
recognized as real, played a crucial role in detecting companions in this
simulation. We mention also our discovery of a previously unknown faint stellar
companion to another of our survey targets, HD 133002. Followup is needed to
confirm this as a physical companion, and to determine its physical properties.


title: Mira B Rejuvenated

abstract:
  Recent ultraviolet spectra from the Hubble Space Telescope (HST) and Far
Ultraviolet Spectroscopic Explorer (FUSE) satellites demonstrate that UV line
and continuum fluxes observed from Mira B are increasing back towards the
levels that the International Ultraviolet Explorer observed in 1979-1980 and
1990-1995, after having been found in a very low state by HST and FUSE in
1999-2001. The UV emission is associated with accretion of material onto Mira B
from Mira A's massive wind, so the variability is presumably due to variations
in accretion rate. From wind absorption features, we estimate a Mira B mass
loss rate of 2.5e-12 M_sun/yr, indicating that Mira B's wind has increased in
strength along with the accretion rate. The UV variability may be associated
with a previously reported 14-year periodicity in Mira B's optical emission.


title:
Properties of Galaxy Groups in the SDSS: II.- AGN Feedback and Star
  Formation Truncation

abstract:
  Successfully reproducing the galaxy luminosity function and the bimodality in
the galaxy distribution requires a mechanism that can truncate star formation
in massive haloes. Current models of galaxy formation consider two such
truncation mechanisms: strangulation, which acts on satellite galaxies, and AGN
feedback, which predominantly affects central galaxies. The efficiencies of
these processes set the blue fraction of galaxies as function of galaxy
luminosity and halo mass. In this paper we use a galaxy group catalogue
extracted from the Sloan Digital Sky Survey (SDSS) to determine these
fractions. To demonstrate the potential power of this data as a benchmark for
galaxy formation models, we compare the results to the semi-analytical model
for galaxy formation of Croton et al. (2006). Although this model accurately
fits the global statistics of the galaxy population, as well as the shape of
the conditional luminosity function, there are significant discrepancies when
the blue fraction of galaxies as a function of mass and luminosity is compared
between the observations and the model. In particular, the model predicts (i)
too many faint satellite galaxies in massive haloes, (ii) a blue fraction of
satellites that is much too low, and (iii) a blue fraction of centrals that is
too high and with an inverted luminosity dependence. In the same order, we
argue that these discrepancies owe to (i) the neglect of tidal stripping in the
semi-analytical model, (ii) the oversimplified treatment of strangulation, and
(iii) improper modeling of dust extinction and/or AGN feedback. The data
presented here will prove useful to test and calibrate future models of galaxy
formation and in particular to discriminate between various models for AGN
feedback and other star formation truncation mechanisms.


title:
Primordial He4 Abundance Constrains the Possible Time Variation of the
  Higgs Vacuum Expectation Value

abstract:
  We constrain the possible time variation of the Higgs vacuum expectation
value ($v$) by recent results on the primordial $^4He$ abundance ($Y_P$). For
that, we use an analytic approach which enables us to take important issues
into consideration, that have been ignored by previous works, like the
$v$-dependence of the relevant cross sections of deuterium production and
photodisintegration, including the full Klein- Nishina cross section.
Furthermore, we take a non-equilibrium Ansatz for the freeze-out concentration
of neutrons and protons and incorporate the latest results on the neutron
decay. Finally, we approximate the key-parameters of the primordial $^4He$
production (the mean lifetime of the free neutron and the binding energy of the
deuteron) by terms of $v\over v_0$ (where $v_0$ denotes the present theoretical
estimate). Eventually, we derive the relation $Y_P \simeq 0.2479 - 5.54
(\frac{v-v_0}{v_0})^2 - 0.808~ (\frac{v-v_0}{v_0})$ and the most stringent
limit on a possible time variation of $v$ is given by: $-5.4 \cdot 10^{-4} \leq
\frac{v-v_0}{v_0} \leq 4.4 \cdot 10^{-4}$.


title: The Connection Between Barstrength and Circumnuclear Dust Structure

abstract:
  We present a comparison of barstrength Qb and circumnuclear dust morphology
for 75 galaxies in order to investigate how bars affect the centers of
galaxies. We trace the circumnuclear dust morphology and amount of dust
structure with structure maps generated from visible-wavelength HST data,
finding that tightly wound nuclear dust spirals are primarily found in weakly
barred galaxies. While strongly barred galaxies sometimes exhibit grand design
structure within the central 10 percent of D25, this structure rarely extends
to within ~10 pc of the galaxy nucleus. In some galaxies, these spiral arms
terminate at a circumnuclear starburst ring. Galaxies with circumnuclear rings
are generally more strongly barred than galaxies lacking rings. Within these
rings, the dust structure is fairly smooth and usually in the form of a loosely
wound spiral. These data demonstrate that multiple nuclear morphologies are
possible in the most strongly barred galaxies: chaotic central dust structure
inconsistent with a coherent nuclear spiral, a grand design spiral that loses
coherence before reaching the nucleus, or a grand design spiral that ends in a
circumnuclear ring. These observations may indicate that not all strong bars
are equally efficient at fueling material to the centers of their host
galaxies. Finally, we investigate the longstanding hypothesis that SB(s)
galaxies have weak bars and SB(r) galaxies have strong bars, finding the
opposite to be the case: namely, SB(r) galaxies are less strongly barred and
have less dust structure than SB(s) galaxies. In general, more strongly barred
galaxies tend to have higher nuclear dust contrast.


title: Chandra Observations of Candidate "True" Seyfert 2 Nuclei

abstract:
  The Unification Model for active galactic nuclei posits that Seyfert 2s are
intrinsically like Seyfert 1s, but that their broad-line regions (BLRs) are
hidden from our view. A Seyfert 2 nucleus that truly lacked a BLR, instead of
simply having it hidden, would be a so-called "true" Seyfert 2. No object has
as yet been conclusively proven to be one. We present a detailed analysis of
four of the best "true" Seyfert 2 candidates discovered to date: IC 3639, NGC
3982, NGC 5283, and NGC 5427. None of the four has a broad H-alpha emission
line, either in direct or polarized light. All four have rich, high-excitation
spectra, blue continua, and Hubble Space Telescope (HST) images showing them to
be unresolved sources with no host-galaxy obscuration. To check for possible
obscuration on scales smaller than that resolvable by HST, we obtained X-ray
observations using the Chandra X-ray Observatory. All four objects show
evidence of obscuration and therefore could have hidden BLRs. The picture that
emerges is of moderate to high, but not necessarily Compton-thick, obscuration
of the nucleus, with extra-nuclear soft emission extended on the
hundreds-of-parsecs scale that may originate in the narrow-line region. Since
the extended soft emission compensates, in part, for the nuclear soft emission
lost to absorption, both absorption and luminosity are likely to be severely
underestimated unless the X-ray spectrum is of sufficient quality to
distinguish the two components. This is of special concern where the source is
too faint to produce a large number of counts, or where the source is too far
away to resolve the extended soft X-ray emitting region.


title: Temporal Variation in Excited Fe^+ Near a GRB Afterglow

abstract:
  Excited Si^+ and Fe^+ species are routinely observed in the host environment
of gamma-ray burst (GRB) afterglows, but are not commonly seen in other
extragalactic locations. Their presence signals unusual properties in the
gaseous environment of these GRB hosts that arise either as a result of the
intense ionizing radiation of the afterglow or through collision excitation in
a dense cloud. In particular, the photon pumping scenario has explicit
expectations for temporal variation in the strength of the excited lines, owing
to the decline in the ionizing flux of the GRB afterglow. We analyze afterglow
spectra of GRB 020813 obtained in two epochs of ~16 hours apart, and examine
transitions from the first excited state of Fe^+ at J=7/2 in these two sets of
data. We report a significant decline by at least a factor of five in the
equivalent width of the FeII 2396 transition, the strongest from the J=7/2
state. We perform a Monte-Carlo analysis and determine that this temporal
variation is present at more than 3sigma level of significance. This
observation represents the first detection in the temporal variation of the
excited Fe+ states in the GRB host ISM, a direct influence of the burst itself
on its environment. We further estimate that the Fe^+ gas resides in 50-100 pc
from the afterglow, based on the afterglow lightcurve and the presence and
absence of the excited FeII 2396 in the two-epoch observations.


title: Gaseous Tidal Debris found in the NGC 3783 Group

abstract:
  We have conducted wide-field HI mapping of a ~5.5 x 5.5 degree region
surrounding the NGC 3783 galaxy group, to an HI mass limit of ~4 x 10^8 Msun.
The observations were made using the multibeam system on the Parkes 64-m
radiotelescope, as part of the Galaxy Evolution Multiwavelength Study (GEMS).
We find twelve HI detections in our Parkes data, four more than catalogued in
HIPASS. We find two new group members, and discover an isolated region of HI
gas with an HI mass of ~4 x 10^8 Msun, without a visible corresponding optical
counterpart. We discuss the likelihood of this HI region being a low surface
brightness galaxy, primordial gas, or a remnant of tidal debris. For the NGC
3783 group we derive a mean recession velocity of 2903 km/s, and a velocity
dispersion of 190 km/s. The galaxy NGC 3783 is the nearest galaxy to the
luminosity weighted centre of the group, and is at the group mean velocity.
  From the X-ray and dynamical state of this galaxy group, this group appears
to be in the early stages of its evolution.


title: pMatlab Parallel Matlab Library

abstract:
  MATLAB has emerged as one of the languages most commonly used by scientists
and engineers for technical computing, with ~1,000,000 users worldwide. The
compute intensive nature of technical computing means that many MATLAB users
have codes that can significantly benefit from the increased performance
offered by parallel computing. pMatlab (www.ll.mit.edu/pMatlab) provides this
capability by implementing Parallel Global Array Semantics (PGAS) using
standard operator overloading techniques. The core data structure in pMatlab is
a distributed numerical array whose distribution onto multiple processors is
specified with a map construct. Communication operations between distributed
arrays are abstracted away from the user and pMatlab transparently supports
redistribution between any block-cyclic-overlapped distributions up to four
dimensions. pMatlab is built on top of the MatlabMPI communication library
(www.ll.mit.edu/MatlabMPI) and runs on any combination of heterogeneous systems
that support MATLAB, which includes Windows, Linux, MacOSX, and SunOS.
Performance is validated by implementing the HPC Challenge benchmark suite and
comparing pMatlab performance with the equivalent C+MPI codes. These results
indicate that pMatlab can often achieve comparable performance to C+MPI at
usually 1/10th the code size. Finally, we present implementation data collected
from a sample of 10 real pMatlab applications drawn from the ~100 users at MIT
Lincoln Laboratory. These data indicate that users are typically able to go
from a serial code to a well performing pMatlab code in about 3 hours while
changing less than 1% of their code.


title: Discovery of two pulsars towards the Galactic Centre

abstract:
  We report the discovery of two highly dispersed pulsars in the direction of
the Galactic Centre made during a survey at 3.1 GHz with the Parkes radio
telescope. Both PSRs J1745-2912 and J1746-2856 have an angular separation from
the Galactic Centre of less than 0.3 degrees and dispersion measures in excess
of 1100 cm-3pc, placing them in the top 10 pulsars when ranked on this value.
The frequency dependence of the scatter-broadening in PSR J1746-2856 is much
shallower than expected from simple theory. We believe it likely that the
pulsars are located between 150 and 500 pc from the Galactic Centre on the near
side, and are part of an excess population of neutron stars associated with the
Centre itself. A second survey made at 8.4 GHz did not detect any pulsars. This
implies either that there are not many bright, long-period pulsars at the
Galactic Centre or that the scattering is more severe at high frequencies than
current models would suggest.


title:
A Search for EUV Emission from Comets with the Cosmic Hot Interstellar
  Plasma Spectrometer (CHIPS)

abstract:
  We have obtained EUV spectra between 90 and 255 \AA of the cometsC/2002 T7
(LINEAR), C/2001 Q4 (NEAT), and C/2004 Q2 (Machholz) near their perihelion
passages in 2004 with the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS).
We obtained contemporaneous data on Comet NEAT Q4 with the $Chandra$ X-ray
Observatory ACIS instrument, marking the first simultaneous EUV and X-ray
spectral observations of a comet. The total CHIPS/EUV observing times were 337
ks for Q4, 234 ks for T7, and 483 ks for Machholz and for both CHIPS and
$Chandra$ we calculate we have captured all the comet flux in the instrument
field of view. We set upper limits on solar wind charge exchange emission lines
of O, C, N, Ne and Fe occurring in the spectral bandpass of CHIPS. The spectrum
of Q4 obtained with $Chandra$ can be reproduced by modeling emission lines of
C, N O, Mg, Fe, Si, S, and Ne solar wind ions. The measured X-ray emission line
intensities are consistent with our predictions from a solar wind charge
exchange model. The model predictions for the EUV emission line intensities are
determined from the intensity ratios of the cascading X-ray and EUV photons
arising in the charge exchange processes. They are compatible with the measured
limits on the intensities of the EUV lines. For comet Q4, we measured a total
X-ray flux of 3.7$\times 10^{-12}$ ergs cm$^{-2}$ s$^{-1}$, and derive from
model predictions a total EUV flux of 1.5$\times 10^{-12}$ erg cm$^{-2}$
s$^{-1}$. The CHIPS observations occurred predominantly while the satellite was
on the dayside of Earth. For much of the observing time, CHIPS performed
observations at smaller solar angles than it was designed for and EUV emission
from the Sun scattered into the instrument limited the sensitivity of the EUV
measurements.


title: Violent Stellar Merger Model for Transient Events

abstract:
  We derive the constraints on the mass ratio for a binary system to merge in a
violent process. We find that the secondary to primary stellar mass ratio
should be ~0.003 < (M_2/M_1) < ~0.15. A more massive secondary star will keep
the primary stellar envelope in synchronized rotation with the orbital motion
until merger occurs. This implies a very small relative velocity between the
secondary star and the primary stellar envelope at the moment of merger, and
therefore very weak shock waves, and low flash luminosity. A too low mass
secondary will release small amount of energy, and will expel small amount of
mass, which is unable to form an inflated envelope. It can however produce a
quite luminous but short flash when colliding with a low mass main sequence
star.
  Violent and luminous mergers, which we term mergebursts, can be observed as
V838 Monocerotis type events, where a star undergoes a fast brightening lasting
days to months, with a peak luminosity of up to ~10^6 Lo followed by a slow
decline at very low effective temperatures.


title: Terrestrial planetary dynamics: a view from U, Th geochemistry

abstract:
  The migration of U and Th inside a planet is controlled by its oxidation
state imposed by the volatile composition. In the deep interior of a planet, an
absence of oxidative volatiles will cause U and Th to stay in a state of metal
or low valance compounds with a big density. Consequently, they migrate to the
bottom of its mantle first, and then are gradually sequestered to its liquid
metal core. Earth is rich in oxidative volatiles including water, therefore, U
and Th in the core can be moved up by an internal circulation system consisting
of the outer core, hot super plumes, asthenosphere and subduction zone (or cold
super plumes). This internal circulation system is the key for the formation of
plate tectonics, the geodynamo and the consequent geomagnetic field. Moreover,
plentiful oxidative volatiles and water within Earth is the precondition to
form such a circulation system. In the early stage (> 4 Ga), Mars developed an
Earth-like internal circulation system due to relatively large amount of
oxidative volatile compositions coming from its building material. This would
have produced a dynamo and correspondingly an Earth-like magnetic field.
However, this internal circulation system was destroyed by one or several giant
impact events in the early stage, which drove off these volatile compositions.
These events also shaped the striking hemispheric dichotomy structure on the
Martian surface. The other result is that its dynamo and geomagnetic field have
also disappeared. Since then, Mars has been the same as Mercury and Venus in
that the heat release from the U and Th in their cores can not be moved by an
internal circulation system gently, but by sporadically catastrophic
resurfacing events (Venus), or super plumes (Mars) or gradual heat conduction
(Mercury).


title:
A search for distant radio galaxies from SUMSS and NVSS: III. radio
  spectral energy distributions and the z-alpha correlation

abstract:
  This is the third in a series of papers that present observations and results
for a sample of 76 ultra-steep-spectrum radio sources designed to find galaxies
at high redshift. Here we present multi-frequency radio observations, from the
Australia Telescope Compact Array, for a subset of 37 galaxies from the sample.
Matched resolution observations at 2.3, 4.8 and 6.2GHz are presented for all
galaxies, with the z<2 galaxies additionally observed at 8.6 and 18GHz. New
angular size constraints are reported for 19 sources based on high resolution
4.8 and 6.2GHz observations. Functional forms for the rest-frame spectral
energy distributions are derived: 89% of the sample is well characterised by a
single power law, whilst the remaining 11% show some flattening toward higher
frequencies: not one source shows any evidence for high frequency steepening.
We discuss the implications of this result in light of the empirical
correlation between redshift and spectral index seen in flux limited samples of
radio galaxies. Finally, a new physical mechanism to explain the redshift --
spectral index correlation is posited: extremely steep spectrum radio galaxies
in the local universe usually reside at the centres of rich galaxy clusters. We
argue that if a higher fraction of radio galaxies, as a function of redshift,
are located in environments with densities similar to nearby rich clusters,
then this could be a natural interpretation for the correlation. We briefly
outline our plans to pursue this line of investigation.


title:
INTEGRAL and XMM-Newton observations towards the unidentified MeV source
  GRO J1411-64

abstract:
  The COMPTEL unidentified source GRO J1411-64 was observed by INTEGRAL, and
its central part, also by XMM-Newton. The data analysis shows no hint for new
detections at hard X-rays. The upper limits in flux herein presented constrain
the energy spectrum of whatever was producing GRO J1411-64, imposing, in the
framework of earlier COMPTEL observations, the existence of a peak in power
output located somewhere between 300-700 keV for the so-called low state. The
Circinus Galaxy is the only source detected within the 4$\sigma$ location error
of GRO J1411-64, but can be safely excluded as the possible counterpart: the
extrapolation of the energy spectrum is well below the one for GRO J1411-64 at
MeV energies. 22 significant sources (likelihood $> 10$) were extracted and
analyzed from XMM-Newton data. Only one of these sources, XMMU
J141255.6-635932, is spectrally compatible with GRO J1411-64 although the fact
the soft X-ray observations do not cover the full extent of the COMPTEL source
position uncertainty make an association hard to quantify and thus risky. The
unique peak of the power output at high energies (hard X-rays and gamma-rays)
resembles that found in the SED seen in blazars or microquasars. However, an
analysis using a microquasar model consisting on a magnetized conical jet
filled with relativistic electrons which radiate through synchrotron and
inverse Compton scattering with star, disk, corona and synchrotron photons
shows that it is hard to comply with all observational constrains. This and the
non-detection at hard X-rays introduce an a-posteriori question mark upon the
physical reality of this source, which is discussed in some detail.


title: Low-mass star formation in Lynds 1333

abstract:
  Medium-resolution optical spectroscopy of the candidate YSOs associated with
the small, nearby molecular cloud Lynds~1333 revealed four previously unknown
classical T Tauri stars, two of which are components of a visual double, and a
Class I source, IRAS 02086+7600. The spectroscopic data, together with new V,R_
C,I_C photometric and 2MASS J, H, and K_s data allowed us to estimate the
masses and ages of the new T Tauri stars. We touch on the possible scenario of
star formation in the region. L1333 is one of the smallest and nearest known
star forming clouds, therefore it may be a suitable target for studying in
detail the small scale structure of a star forming environment.


title: HH135/HH136 - a luminous H$_2$ outflow towards a high-mass protostar

abstract:
  Near-infrared observations towards the luminous IRAS source IRAS11101-5928
and the associated Herbig-Haro objects HH135/HH136 are presented. The
observations reveal the presence of a well-collimated, parsec-sized H$_2$
outflow with a total H$_2$ luminosity of about $2L_\odot$. The bulk of the
molecular gas is characterized by a ro-vibrational excitation temperature of
$2000\pm200$ K. A small fraction (0.3%) of the molecular gas is very hot, with
excitation temperatures around 5500 K. The molecular emission is associated
with strong [FeII] emission. The H$_2$ and [FeII] emission characteristics
indicate the presence of fast, dissociative J-shocks at speeds of $v_\mathrm{s}
\approx$ 100 km s$^{-1}$. Electron densities of $n_\mathrm{e}$ = 3500-4000
cm$^{-3}$ are inferred from the [FeII] line ratios. The large H$_2$ luminosity
combined with the very large source luminosity suggests that the high-mass
protostar that powers the HH135/HH136 flow forms via accretion, but with a
significantly increased accretion rate compared to that of low-mass protostars.


title:
Experimental evidence for magnetorotational instability in a helical
  magnetic field

abstract:
  A recent paper [R. Hollerbach and G. Rudiger, Phys. Rev. Lett. 95, 124501
(2005)] has shown that the threshold for the onset of the magnetorotational
instability (MRI) in a Taylor-Couette flow is dramatically reduced if both
axial and azimuthal magnetic fields are imposed. In agreement with this
prediction, we present results of a Taylor-Couette experiment with the liquid
metal alloy GaInSn, showing evidence for the existence of the MRI at Reynolds
numbers of order 1000 and Hartmann numbers of order 10.


title: Transplanckian signatures in WMAP3?

abstract:
  In this note we investigate how a possible signal in the WMAP3 data of rapid
oscillations in the primordial spectrum can be accommodated into an effective
model of transplanckian physics including back reaction. The results, if due to
a real effect, would indicate the presence of a low fundamental scale --
possibly the string scale -- around $2.2\cdot10^{-5}M_{pl}$.