title:
Chandra Monitoring of the Candidate Anomalous X-ray Pulsar AX
  J1845.0-0258

abstract:
  The population of clearly identified anomalous X-ray pulsars has recently
grown to seven, however, one candidate anomalous X-ray pulsar (AXP) still
eludes re-confirmation. Here, we present a set of seven Chandra ACIS-S
observations of the transient pulsar AX J1845.0-0258, obtained during 2003. Our
observations reveal a faint X-ray point source within the ASCA error circle of
AX J1845.0-0258's discovery, which we designate CXOU J184454.6-025653 and
tentatively identify as the quiescent AXP. Its spectrum is well described by an
absorbed single-component blackbody (kT~2.0 keV) or power law (Gamma~1.0) that
is steady in flux on timescales of at least months, but fainter than AX
J1845.0-0258 was during its 1993 period of X-ray enhancement by at least a
factor of 13. Compared to the outburst spectrum of AX J1845.0-0258, CXOU
J184454.6-025653 is considerably harder: if truly the counterpart, then its
spectral behaviour is contrary to that seen in the established transient AXP
XTE J1810-197, which softened from kT~0.67 keV to ~0.18 keV in quiescence. This
unexpected result prompts us to examine the possibility that we have observed
an unrelated source, and we discuss the implications for AXPs, and magnetars in
general.


title: A simplified approach for Chaplygin-type cosmologies

abstract:
  A new class of accelerating cosmological models driven by a one-parameter
version of the general Chaplygin-type equation of state is proposed. The
simplified version is naturally obtained from causality considerations with
basis on the adiabatic sound speed $v_S$ plus the observed accelerating stage
of the universe. We show that very stringent constraints on the unique free
parameter $\alpha$ describing the simplified Chaplygin model can be obtained
from a joint analysis involving the latest SNe type Ia data and the recent
Sloan Digital Sky Survey measurement of baryon acoustic oscillations (BAO). In
our analysis we have considered separately the SNe type Ia gold sample measured
by Riess et al. (2004) and the Supernova Legacy Survey (SNLS) from Astier et
al. (2006). At 95.4% (c.l.), we find for BAO + \emph{gold} sample, $0.91 \leq
\alpha \leq 1.0$ and $\Omega_{\rm{M}}= 0.28^{+0.043}_{-0.048}$ while BAO + SNLS
analysis provides $0.94 \leq \alpha \leq 1.0$ and $\Omega_{\rm
M}=0.27^{+0.048}_{-0.045}$.


title:
A three stage model for the inner engine of Gamma Ray Burst: Prompt
  emission and early afterglow

abstract:
  We propose a new model within the ``Quark-nova'' scenario to interpret the
recent observations of early afterglows of long Gamma-Ray Bursts (GRB) with the
Swift satellite. This is a three-stage model within the context of a
core-collapse supernova. Stage 1 is an accreting (proto-) neutron star leading
to a possible delay between the core collapse and the GRB. Stage 2 is an
accreting quark-star, generating the prompt GRB. Stage 3, which occurs only if
the quark-star collapses to form a black-hole, consists of an accreting
black-hole. The jet launched in this accretion process interacts with the
ejecta from stage 2, and could generate the flaring activity frequently seen in
X-ray afterglows. This model may be able to account for both the energies and
the timescales of GRBs, in addition to the newly discovered early X-ray
afterglow features.


title:
The Global Evolution of Giant Molecular Clouds. I: Model Formulation and
  Quasi-Equilibrium Behavior

abstract:
  We present semi-analytic dynamical models for giant molecular clouds evolving
under the influence of HII regions launched by newborn star clusters. In
contrast to previous work, we neither assume that clouds are in virial or
energetic equilibrium, nor do we ignore the effects of star formation feedback.
The clouds, which we treat as spherical, can expand and contract homologously.
Photoionization drives mass ejection; the recoil of cloud material both stirs
turbulent motions and leads to an effective confining pressure. The balance
between these effects and the decay of turbulent motions through isothermal
shocks determines clouds' dynamical and energetic evolution. We find that for
realistic values of the rates of turbulent dissipation, photoevaporation, and
energy injection by HII regions, the massive clouds where most molecular gas in
the Galaxy resides live for a few crossing times, in good agreement with recent
observational estimates that large clouds in local group galaxies survive
roughly 20-30 Myr. During this time clouds remain close to equilibrium, with
virial parameters of 1-3 and column densities near 10^22 H atoms cm^-2, also in
agreement with observed cloud properties. Over their lives they convert 5-10%
of their mass into stars, after which point most clouds are destroyed when a
large HII region unbinds them. In contrast, small clouds like those found in
the solar neighborhood only survive ~1 crossing time before being destroyed.


title:
The Tully-Fisher Relation and Its Residuals for a Broadly Selected
  Sample of Galaxies

abstract:
  We measure the relation between galaxy luminosity and disk circular velocity
(the Tully-Fisher [TF] relation), in the g, r, i, and z-bands, for a broadly
selected sample of galaxies from the Sloan Digital Sky Survey, with the goal of
providing well defined observational constraints for theoretical models of
galaxy formation. The input sample of 234 galaxies has a roughly flat
distribution of absolute magnitudes in the range -18.5 > Mr > -22, and our only
morphological selection is an axis-ratio cut b/a < 0.6 to allow accurate
inclination corrections. Long-slit spectroscopy yields usable H-alpha rotation
curves for 162 galaxies. Observational errors, including distance errors due to
peculiar velocities, are small compared to the intrinsic scatter of the TF
relation. The slope of the forward TF relation steepens from -5.5 +/- 0.2
mag/log(km/s) in the g-band to -6.6 +/- 0.2 mag/log(km/s) in the z-band. The
intrinsic scatter is approximately 0.4 mag in all bands. The scatter is not
dominated by rare outliers or by any particular class of galaxies, though it
drops slightly, to 0.36 mag, if we restrict the sample to nearly bulgeless
systems. Correlations of TF residuals with other galaxy properties are weak:
bluer galaxies are significantly brighter than average in the g-band but only
marginally brighter in the i-band; more concentrated galaxies are slightly
fainter than average; and the TF residual is virtually independent of
half-light radius, contrary to the trend expected for gravitationally dominant
disks. The observed residual correlations do not account for most of the
intrinsic scatter, implying that this scatter is instead driven largely by
variations in the ratio of dark to luminous matter within the disk galaxy
population.


title:
The Anatomy of a Magnetar: XMM Monitoring of the Transient Anomalous
  X-ray Pulsar XTE J1810-197

abstract:
  We present the latest results from a multi-epoch timing and spectral study of
the Transient Anomalous X-ray Pulsar XTE J1810-197. We have acquired seven
observations of this pulsar with the Newton X-ray Multi-mirror Mission
(XMM-Newton) over the course of two and a half years, to follow the spectral
evolution as the source fades from outburst. The spectrum is arguably best
characterized by a two-temperature blackbody whose luminosities are decreasing
exponentially with tau_1 = 870 days and tau_2 = 280 days, respectively. The
temperatures of these components are currently cooling at a rate of 22% per
year from a nearly constant value recorded at earlier epochs of kT_1 = 0.25 keV
and kT_2 = 0.67 keV, respectively. The new data show that the temperature T_1
and luminosity of that component have nearly returned to their historic
quiescent levels and that its pulsed fraction, which has steadily decreased
with time, is now consistent with the previous lack of detected pulsations in
quiescence. We also summarize the detections of radio emission from XTE
J1810-197, the first confirmed for any AXP. We consider possible models for the
emission geometry and mechanisms of XTE J1810-197.


title:
Luminosity Dependence in the Fundamental Plane Projections of Elliptical
  Galaxies

abstract:
  We analyze the fundamental plane projections of elliptical galaxies as a
function of luminosity, using a sample of approximately 80,000 galaxies drawn
from Data Release 4 (DR4) of the Sloan Digital Sky Survey (SDSS). We separate
brightest cluster galaxies (BCGs) from our main sample and reanalyze their
photometry due to a problem with the default pipeline sky subtraction for BCGs.
The observables we consider are effective radius (R_e), velocity dispersion
(sigma), dynamical mass (M_dyn ~ R_e sigma2), effective density (sigma2/R_e2),
and effective surface brightness (mu_e). With the exception of the L-M_dyn
correlation, we find evidence of variations in the slope (i.e. the power-law
index) of the fundamental plane projections with luminosity for our normal
elliptical galaxy population. In particular, the radius-luminosity and
Faber-Jackson relations are steeper at high luminosity relative to low
luminosity, and the more luminous ellipticals become progressively less dense
and have lower surface brightnesses than lower luminosity ellipticals. These
variations can be understood as arising from differing formation histories,
with more luminous galaxies having less dissipation. Data from the literature
and our reanalysis of BCGs show that BCGs have radius-luminosity and
Faber-Jackson relations steeper than the brightest non-BCG ellipticals in our
sample, consistent with significant growth of BCGs via dissipationless mergers.
The variations in slope we find in the Faber-Jackson relation of non-BCGs are
qualitatively similar to that reported in the black hole mass-velocity
dispersion (M_BH-sigma) correlation. This similarity is consistent with a
roughly constant value of M_BH/M_star over a wide range of early type galaxies,
where M_star is the stellar mass.


title:
Suzaku Observations of HESS J1616-508: Evidence for a Dark Particle
  Accelerator

abstract:
  We observed the bright unidentified TeV gamma-ray source HESS J1616-508 with
the X-ray Imaging Spectrometers onboard the Suzaku satellite. No X-ray
counterpart was found to a limiting flux of 3.1e-13 erg/s/cm^2 in the 2--10 keV
band, which is some 60 times below the gamma-ray flux in the 1--10 TeV band.
This object is bright in TeV gamma-rays but very dim in the X-ray band, and
thus is one of the best examples in the Galaxy of a "dark particle
accelerator." We also detected soft thermal emission with kT=0.3--0.6 keV near
the location of HESSJ1616. This may be due to the dust grain scattering halo
from the nearby bright supernova remnant RCW103.


title: High frequency oscillations during magnetar flares

abstract:
  The recent discovery of high frequency oscillations during giant flares from
the Soft Gamma Repeaters SGR 1806-20 and SGR 1900+14 may be the first direct
detection of vibrations in a neutron star crust. If this interpretation is
correct it offers a novel means of testing the neutron star equation of state,
crustal breaking strain, and magnetic field configuration. We review the
observational data on the magnetar oscillations, including new timing analysis
of the SGR 1806-20 giant flare using data from the Ramaty High Energy Solar
Spectroscopic Imager (RHESSI) and the Rossi X-ray Timing Explorer (RXTE). We
discuss the implications for the study of neutron star structure and crust
thickness, and outline areas for future investigation.


title: Probable association of T Tauri stars with the L1014 dense core

abstract:
  Using the Wide Field Grism Spectrograph 2 (WFGS2), we have carried out
slit-less spectroscopy, g'r'i' photometry, and slit spectroscopy on the L1014
dense core. We detected three Halpha emission line stars. We interpret one as
weak-line T Tauri star (WTTS) and the others as classical T Tauri stars (CTTS).
Since their g'-i' colors and/or classified spectral types are consistent with
those of T Tauri stars and two of them show less extinction than the cloud,
these three stars are likely to be T Tauri stars associated with L1014.
Adopting an age range for T Tauri stars, 1-10 Myr, the color-magnitude diagram
suggests a distance of ~400-900 pc, rather than the previously assumed
distance, 200 pc. This could strongly affect on the mass estimate of L1014-IRS,
which is thought to be either a very young protostar or proto-brown dwarf.


title: On the age of the TW Hydrae Association and 2M1207334-393254

abstract:
  We have estimated the age of the young moving group TW Hydrae Association, a
cohort of a few dozen stars and brown dwarfs located near the Sun which share
the same kinematic properties and, presumably, the same origin and age. The
chronology has been determined by analyzing different properties (magnitudes,
colors, activity, lithium) of its members and comparing them with several
well-known star forming regions and open clusters, as well as theoretical
models. In addition, by using medium-resolution optical spectra of two M8
members of the association (2M1139 and 2M1207 -an accreting brown dwarf with a
planetary mass companion), we have derived spectral types and measured H(alpha)
and lithium equivalent widths. We have also estimated their effective
temperature and gravity, which were used to produce an independent age
estimation for these two brown dwarfs. We have also collected spectra of
2M1315, a candidate member with a L5 spectral type and measured its H(alpha)
equivalent width. Our age estimate for the association, 10 Myr (in the range
3-20 Myr), agrees with previous values cited in the literature. In the case of
the two brown dwarfs, we have derived an age of 15 Myr (in the range 5-30 Myr),
which also agree with our estimate for the whole group. We compared our results
with recent articles published on the same subject using other techniques, and
discuss the limits of the age-dating techniques.


title:
The distribution of absorption in AGN detected in the XMM-Newton
  observations of the CDFS

abstract:
  We have used very deep XMM-Newton observations of the Chandra Deep
Field-South to examine the spectral properties of the faint active galactic
nucleus (AGN) population. Crucially, redshift measurements are available for
84% (259/309) of the XMM-Newton sample. We have calculated the absorption and
intrinsic luminosities of the sample using an extensive Monte Carlo technique
incorporating the specifics of the XMM-Newton observations. Twenty-three
sources are found to have substantial absorption and intrinsic X-ray
luminosities greater than 10^44 erg/s, putting them in the "type-2" QSO regime.
We compare the redshift, luminosity and absorption distributions of our sample
to the predictions of a range of AGN population models. In contrast to recent
findings from ultra-deep Chandra surveys, we find that there is little evidence
that the absorption distribution is dependent on either redshift or intrinsic
X-ray luminosity. The pattern of absorption in our sample is best reproduced by
models in which ~75% of the AGN population is heavily absorbed at all
luminosities and redshifts.


title: The Cluster Mass Function from Weak Gravitational Lensing

abstract:
  We present the first measurement of the mass function of galaxy clusters
based directly on cluster masses derived from observations of weak
gravitational lensing. To investigate the degree of sample incompleteness
resulting from the X-ray based selection of the target clusters, we use a
sample of 50 clusters with weak lensing mass measurements to empirically
determine the relation between lensing mass and X-ray luminosity and the
scatter about this relation. We use a complete, volume-limited sub-sample of 35
X-ray luminous clusters of galaxies at 0.15<z<0.3 to constrain the abundance of
very massive (M >~ 10^15/h M_sun) clusters. From this, we constrain
sigma_8(Omega_m/0.3)^{0.37} = 0.67^{+0.04}_{-0.05} (68% confidence limits),
agreeing well with constraints from the 3-year WMAP CMB measurements and
estimates of cluster abundances based on X-ray observations, but somewhat lower
than constraints from ``cosmic shear'' weak lensing measurements in random
fields.


title: 3C254: MERLIN observations of a highly asymmetric quasar

abstract:
  Multifrequency, high-resolution radio observations of the quasar 3C254 using
MERLIN are presented. The quasar has a highly asymmetric radio structure, with
the eastern component of the double-lobed structure being much closer to the
nucleus and significantly less polarized than the western one. However, the two
lobes are more symmetric in their total flux densities. The observations show
the detailed structure of the hotspots which are very different on opposite
sides of the radio core, reveal no radio jet and suggest that the
oppositely-directed jets may be intrinsically asymmetric.


title:
A combined re-analysis of existing blank-field SCUBA surveys:
  comparative 850-micron source lists, combined number counts, and evidence for
  strong clustering of the bright sub-mm galaxy population

abstract:
  Taken together, the blank-field sub-mm surveys undertaken with SCUBA prior to
the SHADES survey cover a total area of 460 sq. arcmin to a range of depths.
However combining the results from these surveys has hitherto been complicated
by the fact that different survey groups have used different methods of data
reduction and source extraction. Here we present the results of re-reducing and
analysing all of these blank field SCUBA in an almost identical manner to that
employed in the SCUBA 8-mJy Survey. Comparative source catalogues are given
which include a number of new significant source detections as well as failing
to confirm some of those objects previously published. These new source
catalogues have been combined to produce the most accurate number counts to
date from 2 to 12.5 mJy. The cumulative number counts appear to steepen beyond
S(850)=8mJy, which could indicate an intrinsic turn-over in the underlying
luminosity function placing an upper limit on the luminosity (and hence mass)
of a high redshift galaxy. We have also investigated the clustering properties
of the bright SCUBA population by means of 2-point angular correlation
functions. We find evidence for strong clustering broadly consistent with that
measured for Extremely Red Objects (EROs). Nearest-neighbour analyses further
support strong clustering on arcmin scales, rejecting the null hypothesis that
the distribution of the bright submm sources is random at the 99% confidence
level.


title:
Evidence for a Binary Companion to the Central Compact Object 1E
  1207.4-5209

abstract:
  Unique among neutron stars, 1E 1207.4-5209 is an X-ray pulsar with a spin
period of 424 ms that contains at least two strong absorption features in its
energy spectrum. This neutron star has been identified as a member of the
radio-quiet compact central objects in supernova remnants. It has been found
that 1E 1207.4-5209 is not spinning down monotonically suggesting that this
neutron star undergoes strong, frequent glitches, contains a fall-back disk, or
possess a binary companion. Here, we report on a sequence of seven XMM-Newton
observations of 1E 1207.4-5209 performed during a 40 day window in June/July
2005. Due to unanticipated variance in the phase measurements beyond the
statistical uncertainties, we could not identify a unique phase-coherent timing
solution. The three most probable timing solutions give frequency time
derivatives of +0.9, -2.6, and +1.6 X 10^(-12) Hz/s (listed in descending order
of significance). We conclude that the local frequency derivative during our
XMM-Newton observing campaign differs from the long-term spin-down rate by more
than an order of magnitude, effectively ruling out glitch models for 1E
1207.4-5209. If the long-term spin frequency variations are caused by timing
noise, the strength of the timing noise in 1E 1207.4-5209 is much stronger than
in other pulsars with similar period derivatives. Therefore, it is highly
unlikely that the spin variations are caused by the same physical process that
causes timing noise in other isolated pulsars. The most plausible scenario for
the observed spin irregularities is the presence of a binary companion to 1E
1207.4-5209. We identified a family of orbital solutions that are consistent
with our phase-connected timing solution, archival frequency measurements, and
constraints on the companions mass imposed by deep IR and optical observations.


title:
HD3651B: the first directly imaged brown dwarf companion of an exoplanet
  host star

abstract:
  In the course of our ongoing multiplicity study of exoplanet host stars we
detected a faint companion located at ~43arcsec (480AU physical projected
separation) north-west of its primary -- the exoplanet host star HD3651 at
11pc. The companion, HD3651B, clearly shares the proper motion of the exoplanet
host star in our four images, obtained with ESO/NTT and UKIRT, spanning three
years in epoch difference. The magnitude of the companion is H=16.75+-0.16mag,
the faintest co-moving companion of an exoplanet host star imaged directly.
HD3651B is not detected in the POSS-II B-, R- and I-band images, indicating
that this object is fainter than ~20mag in the B- and R-band and fainter than
\~19mag in the I-band. With the Hipparcos distance of HD3651 of 11pc, the
absolute magnitude of HD3651B is about 16.5mag in the H band. Our H-band
photometry and the Baraffe et al. (2003) evolutionary models yield a mass of
HD3651B to be 20 to 60MJup for assumed ages between 1 and 10Gyr. The effective
temperature ranges between 800 and 900K, consistent with a spectral type of T7
to T8. We conclude that HD3651B is a brown-dwarf companion, the first of its
kind directly imaged as a companion of an exoplanet host star, and one of the
faintest T dwarfs found in the solar vicinity (within 11pc).


title: Faint X-ray Structure in the Crab Pulsar-Wind Nebula

abstract:
  We report on a Chandra observation of the Crab Nebula that gives the first
clear view of the faint boundary of the Crab's X-ray-emitting Pulsar Wind
Nebula, or PWN.
  There is structure in all directions. Fingers, loops, bays, and the South
Pulsar Jet all indicate that either filamentary material or the magnetic field
are controlling the relativistic electrons. In general, spectra soften as
distance from the pulsar increases but do not change rapidly along linear
features. This is particularly true for the Pulsar Jet. The termination of the
Jet is abrupt; the E side is close to an [O {\small III}] optical filament
which may be blocking propagation on this side. We argue that linear features
have ordered magnetic fields and that the structure is determined by the
synchrotron lifetime of particles diffusing perpendicular and parallel to the
magnetic field. We find no significant evidence for thermal X-rays inside the
filamentary envelope.


title:
Astrophysical tau neutrino detection in kilometer-scale Cherenkov
  detectors via muonic tau decay

abstract:
  Kilometer-scale deep under-ice or -water Cherenkov neutrino detectors may
detect muon and electron neutrinos from astrophysical sources at energies of a
TeV and above. Tau neutrinos are also expected from these sources due to
neutrino flavor oscillations in vacuum, and tau neutrinos are free of
atmospheric background at a much lower energy than muon and electron neutrinos.
Identification of tau neutrinos is expected to be possible above the PeV energy
range through the "double bang" and "lollipop" signatures. We discuss another
signature of tau in the PeV-EeV range, arising from the decay of tau leptons
inside the detector to much brighter muons.


title:
Hubble Space Telescope Observations of Comet 9P/Tempel 1 during the Deep
  Impact Encounter

abstract:
  We report on the Hubble Space Telescope program to observe periodic comet
9P/Tempel 1 in conjunction with NASA's Deep Impact mission. Our objectives were
to study the generation and evolution of the coma resulting from the impact and
to obtain wide-band images of the visual outburst generated by the impact. Two
observing campaigns utilizing a total of 17 HST orbits were carried out: the
first occurred on 2005 June 13-14 and fortuitously recorded the appearance of a
new, short-lived fan in the sunward direction on June 14. The principal
campaign began two days before impact and was followed by contiguous orbits
through impact plus several hours and then snapshots one, seven, and twelve
days later. All of the observations were made using the Advanced Camera for
Surveys (ACS). For imaging, the ACS High Resolution Channel (HRC) provides a
spatial resolution of 36 km (16 km/pixel) at the comet at the time of impact.
Baseline images of the comet, made prior to impact, photometrically resolved
the comet's nucleus. The derived diameter, 6.1 km, is in excellent agreement
with the 6.0 +/- 0.2 km diameter derived from the spacecraft imagers. Following
the impact, the HRC images illustrate the temporal and spatial evolution of the
ejecta cloud and allow for a determination of its expansion velocity
distribution. One day after impact the ejecta cloud had passed out of the
field-of-view of the HRC.


title: Fusion reactions in multicomponent dense matter

abstract:
  We analyze thermonuclear and pycnonuclear fusion reactions in dense matter
containing atomic nuclei of different types. We extend a phenomenological
expression for the reaction rate, proposed recently by Gasques et al. (2005)
for the one-component plasma of nuclei, to the multi-component plasma. The
expression contains several fit parameters which we adjust to reproduce the
best microscopic calculations available in the literature. Furthermore, we show
that pycnonuclear burning is drastically affected by an (unknown) structure of
the multi-component matter (a regular lattice, a uniform mix, etc.). We apply
the results to study nuclear burning in a carbon_12-oxygen_16 mixture. In this
context we present new calculations of the astrophysical S-factors for
carbon-oxygen and oxygen-oxygen fusion reactions. We show that the presence of
a CO lattice can strongly suppress carbon ignition in white dwarf cores and
neutron star crusts at densities > 3e9 g cm^{-3} and temperatures T<1e8 K.


title: On the Search For Transits of the Planets Orbiting Gl 876

abstract:
  We report the results of a globally coordinated photometric campaign to
search for transits by the P ~ 30 d and P ~ 60 d outer planets of the 3-planet
system orbiting the nearby M-dwarf Gl 876. These two planets experience strong
mutual perturbations, which necessitate use of a dynamical (four-body) model to
compute transit ephemerides for the system. Our photometric data have been
collected from published archival sources, as well as from our photometric
campaigns that were targeted to specific transit predictions. Our analysis
indicates that transits by planet "c" (P ~ 30 d) do not currently occur, in
concordance with the best-fit i = 50 degree co-planar configuration obtained by
dynamical fits to the most recent radial velocity data for the system. Transits
by planet "b" (P ~ 60 d) are not entirely ruled out by our observations, but
our data indicate that it is very unlikely that they occur. Our experience with
the Gl 876 system suggests that a distributed ground-based network of small
telescopes can be used to search for transits of very low mass M-stars by
terrestrial-sized planets.


title:
Nucleosynthesis in neutrino heated matter: The vp-process and the
  r-process

abstract:
  This manuscript reviews recent progress in our understanding of the
nucleosynthesis of medium and heavy elements in supernovae. Recent
hydrodynamical models of core-collapse supernovae show that a large amount of
proton rich matter is ejected under strong neutrino fluxes. This matter
constitutes the site of the vp-process where antineutrino absorption reactions
catalyze the nucleosynthesis of nuclei with A > 64. Supernovae are also
associated with the r-process responsible for the synthesis of the heaviest
elements in nature. Fission during the r-process can play a major role in
determining the final abundance patter and in explaining the almost universal
features seen in metal-poor r-process-rich stars.


title: Effect of turbulent diffusion on iron abundance profiles

abstract:
  We compare the observed peaked iron abundance profiles for a small sample of
groups and clusters with the predictions of a simple model involving the metal
ejection from the brightest galaxy and the subsequent diffusion of metals by
stochastic gas motions. Extending the analysis of Rebusco et al. (2005) we
found that for 5 out of 8 objects in the sample an effective diffusion
coefficient of the order of $10^{29}$ cm$^{2}$ s$^{-1}$ is needed. For AWM4,
Centaurus and AWM7 the results are different suggesting substantial
intermittence in the process of metal spreading across the cluster. There is no
obvious dependence of the diffusion coefficient on the mass of the system.
  We also estimated the characteristic velocities and the spatial scales of the
gas motions needed to balance the cooling losses by the dissipation of the same
gas motions. A comparison of the derived spatial scales and the sizes of
observed radio bubbles inflated in the ICM by a central active galactic nucleus
(AGN) suggests that the AGN/ICM interaction makes an important (if not a
dominant) contribution to the gas motions in the cluster cores.


title: Thermal neutrinos from pre-supernova

abstract:
  We would like to discuss prospects for neutrino observations of the
core-collapse supernova progenitor during neutrino-cooled stage. We will
present new theoretical results on thermal neutrino and antineutrino spectra
produced deep inside the pre-supernova core. Three competing processes: pair-,
photo and plasma-neutrino production, are taken into account. The results will
be used to estimate signal in existing and future neutrino detectors. Chance
for supernova prediction is estimated, with possible aid to core-collapse
neutrino and gravitational wave detectors in the form of early warning.


title: LISA Observations of Supermassive Black Hole Growth

abstract:
  Based on a high resolution cosmological n-body simulation, we track the
hierarchical growth of black holes in galaxy clusters from z=20 to z=0. We
present a census of black holes as function of redshift and will determine
their mass assembly history under a variety of assumptions regarding the
importance of gas accretion in black hole growth, from early supercritical
Eddington accretion to gas-poor hierarchical assembly. Following a galaxy
merger, black holes are expected to form, inspiral and merge after strongly
radiating energy via gravitational waves. For each binary black hole inspiral
and merger, we determine the expected gravitational wave signal for the Laser
Interferometer Space Antenna (LISA), and calculate the LISA event rate as a
function of time. We will calculate the black hole mass assembly history for
several black hole growth scenerios, so that we can explore tests to
characterize each model observationally. In particular, we will study how well
LISA observations will be able to distinguish between these very different
assembly scenarios.


title:
A Technique for Weak Lensing with Velocity Maps: Eliminating Ellipticity
  Noise in HI Radio Observations

abstract:
  Weak lensing surveys have become a powerful tool for mapping mass
distributions and constraining the expansion history of our Universe, but
continuum surveys must average over a large number of galaxies to average down
the ellipticity noise due to the unknown ellipticity and orientation of the
lensed galaxies. This Letter presents a technique for measuring weak lensing
with velocity maps that avoids the ellipticity noise. By studying the inherent
noise characteristics, we argue this new technique could rival or exceed the
sensitivity of traditional continuum observations for upcoming HI radio
surveys.


title:
The survival and disruption of CDM micro-haloes: implications for direct
  and indirect detection experiments

abstract:
  If the dark matter particle is a neutralino then the first structures to form
are cuspy cold dark matter (CDM) haloes collapsing after redshifts z ~ 100 in
the mass range 10^{-6} - 10^{-3} Msun. We carry out a detailed study of the
survival of these micro-haloes in the Galaxy as they experience tidal
encounters with stars, molecular clouds, and other dark matter substructures.
We test the validity of analytic impulsive heating calculations using high
resolution N-body simulations. A major limitation of analytic estimates is that
mean energy inputs are compared to mean binding energies, instead of the actual
mass lost from the system. This energy criterion leads to an overestimate of
the stripped mass and underestimate of the disruption timescale since CDM
haloes are strongly bound in their inner parts. We show that a significant
fraction of material from CDM micro-haloes can be unbound by encounters with
Galactic substructure and stars, however the cuspy central regions remain
relatively intact. Furthermore, the micro-haloes near the solar radius are
those which collapse significantly earlier than average and will suffer very
little mass loss. Thus we expect a fraction of surviving bound micro-haloes, a
smooth component with narrow features in phase space, which may be uncovered by
direct detection experiments, as well as numerous surviving cuspy cores with
proper motions of arc-minutes per year, which can be detected indirectly via
their annihilation into gamma-rays.


title: Gravitational lensing model degeneracies: Is steepness all-important?

abstract:
  In gravitational lensing, steeper mass profiles generically produce longer
time delays but smaller magnifications, without necessarily changing the image
positions or magnification ratios between different images. This is well known.
We find in this paper, however, that even if steepness is fixed, time delays
can still have significant model dependence, which we attribute to shape
modeling degeneracies. This conclusion follows from numerical experiments with
models of 35 galaxy lenses. We suggest that varying and twisting ellipticities,
features that are explored by pixelated lens models but not so far by
parametric models, have an important effect on time delays.


title:
The Centaurus Group and the Outer Halo of NGC 5128: Are they Dynamically
  Connected?

abstract:
  NGC 5128, a giant elliptical galaxy only $\sim 4$ Mpc away, is the dominant
member of a galaxy group of over 80 probable members. The Centaurus group
provides an excellent sample for a kinematic comparison between the halo of NGC
5128 and its surrounding satellite galaxies. A new study, presented here, shows
no kinematic difference in rotation amplitude, rotation axis, and velocity
dispersion between the halo of NGC 5128, determined from over $\sim340$ of its
globular clusters, and those of the Centaurus group as a whole. These results
suggest NGC 5128 could be behaving in part as the inner component to the galaxy
group, and could have begun as a large initial seed galaxy, gradually built up
by minor mergers and satellite accretions, consistent with simple cold dark
matter models. The mass and mass-to-light ratios in the B-band, corrected for
projection effects, are determined to be $(1.3\pm0.5) \times 10^{12}$
M$_{\sun}$ and $52\pm22$ M$_{\sun}$/L$_{\sun}$ for NGC 5128 out to a
galactocentric radius of 45 kpc, and $(9.2\pm3.0) \times 10^{12}$ M$_{\sun}$
and $153\pm50$ M$_{\sun}$/L$_{\sun}$ for the Centaurus group, consistent with
previous studies.


title:
Galaxy Clusters Associated with Short GRBs. I. The Fields of GRBs
  050709, 050724, 050911 and 051221a

abstract:
  We present a search for galaxy clusters in the fields of three bona-fide
short GRBs (050709, 050724, and 051221a) and the putative short burst GRB
050911 using multi-slit optical spectroscopy. These observations are part of a
long-term program to constrain the progenitor age distribution based on the
fraction of short GRBs in galaxy clusters and early-type galaxies. We find no
evidence for cluster associations at the redshifts of the first three bursts,
but we confirm the presence of the cluster EDCC 493 within the error circle of
GRB 050911 and determine its redshift, z=0.1646, and velocity dispersion, ~660
km/s. In addition, our analysis of Swift/XRT observations of this burst reveals
diffuse X-ray emission coincident with the optical cluster position, with a
luminosity, 4.9e42 erg/s, and a temperature, kT=0.9 keV. The inferred mass of
the cluster is 2.5e13 Msun, and the probability of chance coincidence is about
0.1-1%, indicating an association with GRB 050911 at the 2.6-3.2 sigma
confidence level. A search for diffuse X-ray emission in coincidence with the
fifteen other short GRBs observed with XRT and Chandra reveals that with the
exception of the previously noted cluster ZwCl 1234.0+02916 likely associated
with GRB 050509b, no additional associations are evident to a typical limit of
3e-14 erg/s/cm^2, or M<5e13 Msun assuming a typical z=0.3. The resulting
fraction of short GRBs hosted by galaxy clusters of about 20% is in rough
agreement with the fraction of stellar mass in clusters of ~10-20%.


title:
Using Weak Lensing Dilution to Improve Measurements of the Luminous and
  Dark Matter in A1689

abstract:
  The E/SO sequence of a cluster defines a boundary redward of which a reliable
weak lensing signal can be obtained from background galaxies, uncontaminated by
cluster members. For bluer colors, both background and cluster members are
present, reducing the distortion signal by the proportion of unlensed cluster
members. In deep Subaru and HST/ACS images of A1689 the tangential distortion
of galaxies with bluer colors falls rapidly toward the cluster center relative
to the lensing signal of the red background. We use this dilution effect to
derive the cluster light profile and luminosity function to large radius, with
the advantage that no subtraction of far-field background counts is required.
The light profile declines smoothly to the limit of the data, r<2Mpc/h, with a
constant slope, dlog(L)/dlog(r)=-1.12+-0.06, unlike the lensing mass profile
which steepens continuously with radius, so that M/L peaks at an intermediate
radius, ~100kpc/h. A flatter behavior is found for the more physically
meaningful ratio of dark-matter to stellar-matter, when accounting for the
color-mass relation of cluster members. The cluster luminosity function has a
flat slope, alpha=-1.05+-0.07, independent of radius and with no faint upturn
to M_i'<-12. We establish that the very bluest objects are negligibly
contaminated by the cluster V-i'<0.2, because their distortion profile rises
towards the center following the red background, but offset higher by ~20%.
This larger amplitude is consistent with the greater estimated depth of the
faint blue galaxies, z~=2.0 compared to z~=0.85 for the red background, a
purely geometric effect related to cosmological parameters. Finally, we improve
upon our earlier mass profile by combining both the red and blue background
populations, clearly excluding low concentration CDM profiles.


title: Map Projections Minimizing Distance Errors

abstract:
  It is useful to have mathematical criteria for evaluating errors in map
projections. The Chebyshev criterion for minimizing rms (root mean square)
local scale factor errors for conformal maps has been useful in developing
conformal map projections of continents. Any local error criterion will be
minimized ultimately by map projections with multiple interruptions, on which
some pairs of points that are close on the globe are far apart on the map.
Since it is as bad to have two points on the map at two times their proper
separation as to have them at half their proper separation, it is the rms
logarithmic distance, s, between random points in the mapped region that we
will minimize. The best previously known projection of the entire sphere for
distances is the Lambert equal-area azimuthal with an rms logarithmic distance
error of s=0.343. For comparison, the Mercator has s=0.444, and the Mollweide
has s=0.390. We present new projections: the "Gott equal-area elliptical" with
perfect shapes on the central meridian, the "Gott-Mugnolo equal-area
elliptical" and the "Gott-Mugnolo azimuthal" with rms logarithmic distance
errors of s=0.365, s=0.348, and s=0.341 respectively, which improve on previous
projections of their type. The "Gott-Mugnolo azimuthal" has the lowest distance
errors of any map and is produced by a new technique using "forces" between
pairs of points on a map which make them move so as to minimize s. The "Gott
equal-area elliptical" projection produces a particularly attractive map of
Mars, and the "Gott-Mugnolo azimuthal" projection produces an interesting map
of the moon.


title: Flexion and Skewness in Map Projections of the Earth

abstract:
  Tissot indicatrices have provided visual measures of local area and isotropy
distortions. Here we show how large scale distortions of flexion (bending) and
skewness (lopsidedness) can be measured. Area and isotropy distortions depend
on the map projection metric, flexion and skewness, which manifest themselves
on continental scales, depend on the first derivatives of the metric. We
introduce new indicatrices that show not only area and isotropy distortions but
flexion and skewness as well. We present a table showing error measures for
area, isotropy, flexion, skewness, distances, and boundary cuts allowing us to
compare different world map projections. We find that the Winkel-Tripel
projection (already adopted for world maps by the National Geographic), has low
distortion on most measures and excellent quality overall.


title: Constraining Black Hole Spin Via X-ray Spectroscopy

abstract:
  We present an analysis of the observed broad iron line feature and putative
warm absorber in the long 2001 XMM-Newton observation of the Seyfert-1.2 galaxy
MCG-6-30-15. The new "kerrdisk" model we have designed for simulating line
emission from accretion disk systems allows black hole spin to be a free
parameter in the fit, enabling the user to formally constrain the angular
momentum of a black hole, among other physical parameters of the system. In an
important extension of previous work, we derive constraints on the black hole
spin in MCG-6-30-15 using a self-consistent model for X-ray reflection from the
surface of the accretion disk while simultaneously accounting for absorption by
dusty photoionized material along the line of sight (the warm absorber). Even
including these complications, the XMM-Newton/EPIC-pn data require extreme
relativistic broadening of the X-ray reflection spectrum; assuming no emission
from within the radius of marginal stability, we derive a formal constraint on
the dimensionless black hole spin parameter of a > 0.987 at 90% confidence. The
principal unmodeled effect that can significantly reduce the inferred black
hole spin is powerful emission from within the radius of marginal stability.
Although significant theoretical developments are required to fully understand
this region, we argue that the need for a rapidly spinning black hole is robust
to physically plausible levels of emission from within the radius of marginal
stability. In particular, we show that a non-rotating black hole is strongly
ruled out.


title: Intracluster Medium through three years of WMAP

abstract:
  Wilkinson Microwave Anisotropy Probe (WMAP) has provided us with the yet
highest resolution all-sky maps of the Cosmic Microwave Background. As a result
of thermal Sunyaev-Zel'dovich effect, clusters of galaxies are imprinted as
tiny, poorly resolved dips on top of primary CMB anisotropies in these maps.
Here, I describe different efforts to extract the physics of Intracluster
Medium (ICM) from the sea of primary CMB, through combining WMAP with
low-redshift galaxy or X-ray cluster surveys. This finally culminates at a mean
(universal) ICM pressure profile, which is for the first time directly
constrained from WMAP 3yr maps, and leads to interesting constraints on the ICM
baryonic budget.


title: Accurate fundamental parameters for Lower Main Sequence Stars

abstract:
  We derive an empirical effective temperature and bolometric luminosity
calibration for G and K dwarfs, by applying our own implementation of the
InfraRed Flux Method to multi-band photometry. Our study is based on 104 stars
for which we have excellent BVRIJHK photometry, excellent parallaxes and good
metallicities. Colours computed from the most recent synthetic libraries
(ATLAS9 and MARCS) are found to be in good agreement with the empirical colours
in the optical bands, but some discrepancies still remain in the infrared.
Synthetic and empirical bolometric corrections also show fair agreement. A
careful comparison to temperatures, luminosities and angular diameters obtained
with other methods in literature shows that systematic effects still exist in
the calibrations at the level of a few percent. Our InfraRed Flux Method
temperature scale is 100K hotter than recent analogous determinations in the
literature, but is in agreement with spectroscopically calibrated temperature
scales and fits well the colours of the Sun. Our angular diameters are
typically 3% smaller when compared to other (indirect) determinations of
angular diameter for such stars, but are consistent with the limb-darkening
corrected predictions of the latest 3D model atmospheres and also with the
results of asteroseismology. Very tight empirical relations are derived for
bolometric luminosity, effective temperature and angular diameter from
photometric indices. We find that much of the discrepancy with other
temperature scales and the uncertainties in the infrared synthetic colours
arise from the uncertainties in the use of Vega as the flux calibrator. Angular
diameter measurements for a well chosen set of G and K dwarfs would go a long
way to addressing this problem.


title: Non-Circular beam correction to the CMB power spectrum

abstract:
  In the era of high precision CMB measurements, systematic effects are
beginning to limit the ability to extract subtler cosmological information. The
non-circularity of the experimental beam has become progressively important as
CMB experiments strive to attain higher angular resolution and sensitivity. The
effect of non-circular beam on the power spectrum is important at multipoles
larger than the beam-width. For recent experiments with high angular
resolution, optimal methods of power spectrum estimation are computationally
prohibitive and sub-optimal approaches, such as the Pseudo-Cl method, are used.
We provide an analytic framework for correcting the power spectrum for the
effect of beam non-circularity and non-uniform sky coverage (including
incomplete/masked sky maps). The approach is perturbative in the distortion of
the beam from non-circularity allowing for rapid computations when the beam is
mildly non-circular. When non-circular beam effect is important, we advocate
that it is computationally advantageous to employ `soft' azimuthally apodized
masks whose spherical harmonic transform die down fast with m.


title:
Theoretical Limits on Extrasolar Terrestrial Planet Detection with
  Coronagraphs

abstract:
  Many high contrast coronagraph designs have recently been proposed. In this
paper, their suitability for direct imaging of extrasolar terrestrial planets
is reviewed. We also develop a linear-algebra based model of coronagraphy that
can both explain the behavior of existing coronagraphs and quantify the
coronagraphic performance limit imposed by fundamental physics. We find that
the maximum theoretical throughput of a coronagraph is equal to one minus the
non-aberrated non-coronagraphic PSF of the telescope. We describe how a
coronagraph reaching this fundamental limit may be designed, and how much
improvement over the best existing coronagraph design is still possible. Both
the analytical model and numerical simulations of existing designs also show
that this theoretical limit rapidly degrades as the source size is increased:
the ``highest performance'' coronagraphs, those with the highest throughput and
smallest Inner Working Angle (IWA), are the most sensitive to stellar angular
diameter. This unfortunately rules out the possibility of using a small IWA
(lambda/d) coronagraph for a terrestrial planet imaging mission.
  Finally, a detailed numerical simulation which accurately accounts for
stellar angular size, zodiacal and exozodiacal light is used to quantify the
efficiency of coronagraph designs for direct imaging of extrasolar terrestrial
planets in a possible real observing program. We find that in the photon noise
limited regime, a 4m telescope with a theoretically optimal coronagraph is able
to detect Earth-like planets around 50 stars with 1hr exposure time per target
(assuming 25% throughput and exozodi levels similar to our solar system). We
also show that at least 2 existing coronagraph design can approach this level
of performance in the ideal monochromatic case considered in this study.


title:
VLBI observations of the most radio-loud, narrow-line quasar SDSS
  J094857.3+002225

abstract:
  We observed the narrow-line quasar SDSS J094857.3+002225, which has the
highest known radio loudness for a narrow-line Seyfert~1 galaxy (NLS1), at
1.7--15.4 GHz with the Very Long Baseline Array (VLBA). This is the first
very-long-baseline interferometry (VLBI) investigation for a radio-loud NLS1.
We independently found very high brightness temperatures from (1) its
compactness in a VLBA image and (2) flux variation among the VLBA observation,
our other observations with the VLBA, and the Very Large Array (VLA). A Doppler
factor larger than 2.7--5.5 was required to meet an intrinsic limit of
brightness temperature in the rest frame. This is evidence for highly
relativistic nonthermal jets in an NLS1. We suggest that the Doppler factor is
one of the most crucial parameters determining the radio loudness of NLS1s. The
accretion disk of SDSS J094857.3+002225 is probably in the very high state,
rather than the high/soft state, by analogy with X-ray binaries with strong
radio outbursts and superluminal jets such as GRS 1915+105.


title:
Gravitational scalar field coupled directly to the Maxwell field and its
  effect to solar-system experiments

abstract:
  The effect of the massless gravitational scalar field assumed to couple
directly to the Maxwell field to the solar-system experiments is estimated. We
start with discussing the theoretical significances of this coupling. Rather
disappointingly, however, we find that the scalar-field parameters never affect
the observation in the limit of the geometric optics, indicating a marked
difference from the well-known contribution through the spacetime metric.


title:
Neutrino signals from the formation of black hole: a probe of equation
  of state of dense matter

abstract:
  The gravitational collapse of a non-rotating, black-hole-forming massive star
is studied by neutrino-radiation-hydrodynamical simulations for two different
sets of realistic equation of state of dense matter. We show that the event
will produce as many neutrinos as the ordinary supernova, but with distinctive
characteristics in luminosities and spectra that will be an unmistakable
indication of black hole formation. More importantly, the neutrino signals are
quite sensitive to the difference of equation of state and can be used as a
useful probe into the properties of dense matter. The event will be unique in
that they will be shining only by neutrinos (and, possibly, gravitational
waves) but not by photons, and hence they should be an important target of
neutrino astronomy.


title:
Deep imaging survey of the environment of Alpha Centauri - I. Adaptive
  optics imaging of Alpha Cen B with VLT-NACO

abstract:
  Context: Alpha Centauri is our closest stellar neighbor, at a distance of
only 1.3 pc, and its two main components have spectral types comparable to the
Sun. This is therefore a favorable target for an imaging search for extrasolar
planets. Moreover, indications exist that the gravitational mass of Alpha Cen B
is higher than its modeled mass, the difference being consistent with a
substellar companion of a few tens of Jupiter masses. Aims: We searched for
faint comoving companions to Alpha Cen B. As a secondary objective, we built a
catalogue of the detected background sources. Methods: We used the NACO
adaptive optics system of the VLT in the J, H, and Ks bands to search for
companions to Alpha Cen B. This instrument allowed us to achieve a very high
sensitivity to point-like sources, with a limiting magnitude of m\_Ks ~ 18 at
7" from the star. We complemented this data set with archival coronagraphic
images from the HST-ACS instrument to obtain an accurate astrometric
calibration. Results: Over the observed area, we did not detect any comoving
companion to Alpha Cen B down to an absolute magnitude of 19-20 in the H and Ks
bands. However, we present a catalogue of 252 background objects within about
15" of the star. This catalogue fills part of the large void area that
surrounds Alpha Cen in sky surveys due to the strong diffused light. We also
present a model of the diffused light as a function of angular distance for the
NACO instrument, that can be used to predict the background level for bright
star observations. Conclusions: According to recent numerical models, the
limiting magnitude of our search sets the maximum mass of possible companions
to 20-30 times Jupiter, between 7 and 20 AU from Alpha Cen B.


title:
Quantifying galactic clustering and departures from randomness of the
  inter-galactic void probability function using information geometry

abstract:
  We study a family of parametric statistical models based on gamma
distributions, which do give realistic descriptions for other stochastic porous
media. Gamma distributions contain as a special case the exponential
distributions, which correspond to the `random' void size probability arising
from Poisson processes.
  The space of parameters is a surface with a natural Riemannian metric
structure. This surface contains the Poisson processes as an isometric
embedding and a recent theorem shows that it contains neighbourhoods of all
departures from randomness. The method provides thereby a geometric setting for
quantifying departures from randomness and on which may be formulated
cosmological evolutionary dynamics for galactic clustering and for the
concomitant development of the void size distribution.
  The 2dFGRS data offer the possibility of more detailed investigation of this
approach than was possible when it was originally suggested and some parameter
estimations are given.


title:
Luminosity Functions of Lyman-Break Galaxies at z~4 and 5 in the Subaru
  Deep Field

abstract:
  We investigate the luminosity functions of Lyman-break galaxies (LBG) at z~4
and 5 based on the optical imaging data obtained in the Subaru Deep Field
Project. Three samples of LBGs in a contiguous 875 arcmin^2 area are
constructed. One consists of 3,808 LBGs at z~4 down to i'=26.85 selected with
the B-R vs R-i' diagram. The other two consist of 539 and 240 LBGs at z~5 down
to z'=26.05 selected with two kinds of two-color diagrams: V-i' vs i'-z' and
R-i' vs i'-z'. The adopted selection criteria are proved to be fairly reliable
by spectroscopic observation. We derive the luminosity functions of the LBGs at
rest-frame ultraviolet wavelengths down to M_{UV}=-19.2 at z~4 and M_{UV}=-20.3
at z~5. We find clear evolution of the luminosity function over the redshift
range of 0<z<6, which is accounted for by a sole change in the characteristic
magnitude, M^*. The cosmic star formation rate (SFR) density at z~4 and z~5 is
measured from the luminosity functions. We examine the evolution of the cosmic
SFR density and its luminosity dependence over 0<z<6. The SFR density
contributed from brighter galaxies is found to change more drastically with
cosmic time. The contribution from brighter galaxies has a sharp peak around
z=3-4, while that from fainter galaxies evolves relatively mildly with a broad
peak at earlier epoch. Combining the observed SFR density with the standard
Cold Dark Matter model, we compute the cosmic SFR per unit baryon mass in dark
haloes, i.e., the specific SFR. The specific SFR is found to scale with
redshift as (1+z)^3 up to z~4, implying that the efficiency of star formation
is on average higher at higher redshift in proportion to the cooling rate
within dark haloes, while this is not simply the case at z>4.


title: Detection of a population gradient in the Sagittarius Stream

abstract:
  We present a quantitative comparison between the Horizontal Branch morphology
in the core of the Sagittarius dwarf spheroidal galaxy (Sgr) and in a wide
field sampling a portion of its tidal stream (Sgr Stream), located tens of kpc
away from the center of the parent galaxy. We find that the Blue Horizontal
Branch (BHB) stars in that part of the Stream are five times more abundant than
in the Sgr core, relative to Red Clump stars. The difference in the ratio of
BHB to RC stars between the two fields is significant at the 4.8 sigma level.
This indicates that the old and metal-poor population of Sgr was preferentially
stripped from the galaxy in past peri-Galactic passages with respect to the
intermediate-age metal rich population that presently dominates the bound core
of Sgr, probably due to a strong radial gradient that was settled within the
galaxy before its disruption. The technique adopted in the present study allows
to trace population gradients along the whole extension of the Stream.


title:
Detection potential to point-like neutrino sources with the NEMO-km3
  telescope

abstract:
  The NEMO Collaboration is conducting an R&D activity towards the construction
of a Mediterranean km3 neutrino telescope. In this work, we present the results
of Monte Carlo simulation studies on the capability of the proposed NEMO
telescope to detect and identify point-like sources of high energy muon
neutrinos.


title: Sensitivity of the NEMO telescope to neutrinos from microquasars

abstract:
  We present the results of Monte Carlo simulation studies of the capability of
the proposed NEMO telescope to detect TeV muon neutrinos from Galactic
microquasars. In particular we determined the number of the detectable events
from each known microquasar together with the expected atmospheric neutrino and
muon background events. We also discuss the detector sensitivity to neutrino
fluxes expected from microquasars, optimizing the event selection in order to
reject the atmospheric background, and we show the number of events surviving
the event selection.


title: Winds and Infalling Gas in Lyman Break Galaxies

abstract:
  A model for gas outflows is proposed which simultaneously explains the
correlations between the (i) equivalent width of low ionization and Ly-alpha
lines, (ii) outflow velocity, and (iii) star formation rate observed in Lyman
Break Galaxies (LBGs). Our interpretation implies that LBGs host short-lived
(30 +/- 5 Myr) starburst episodes observed at different evolutionary phases.
Initially, the starburst powers a hot wind bound by a denser cold shell, which
after about 5 Myr becomes dynamically unstable and fragments; afterwards the
fragment evolution is approximately ballistic while the hot bubble continues to
expand. As the fragments are gravitationally decelerated, their screening
ability of the starlight decreases as the UV starburst luminosity progressively
dims. LBG observations sample all these evolutionary phases. Finally, the
fragments fall back onto the galaxy after approximately 60 Myr. This phase
cannot be easily probed as it occurs when the starburst UV luminosity has
already largely faded; however, galaxies dimmer in the UV than LBGs should show
infalling gas.


title:
Suppression of star formation in early-type galaxies by feedback from
  supermassive black holes

abstract:
  Detailed high-resolution observations of the innermost regions of nearby
galaxies have revealed the presence of supermassive black holes1. These black
holes may interact with their host galaxies by means of 'feedback' in the form
of energy and material jets; this feedback affects the evolution of the host
and gives rise to observed relations between the black hole and the host. Here
we report observations of the ultraviolet emissions of massive early-type
galaxies. We derive an empirical relation for a critical black-hole mass (as a
function of velocity dispersion) above which the outflows from these black
holes suppress star formation in their hosts by heating and expelling all
available cold gas. Supermassive black holes are negligible in mass compared to
their hosts but nevertheless seem to play a critical role in the star formation
history of galaxies.


title: A torque reversal of 4U 1907+09

abstract:
  We present an analysis of the accreting X-ray pulsar system 4U 1907+09 based
on INTEGRAL data. The main focus of this analysis is a study of the timing
behavior of this source. In addition we also show an analysis of the 5-90 keV
spectrum. The data were extracted using the official INTEGRAL software OSA 5.1.
Timing analysis was performed using epoch folding and pulsar pulse phasing. We
have measured 12 individual pulse periods for the years 2003 to 2005. We
confirm earlier RXTE results that during 2003 the spin down became slower and
show furthermore that after this phase 4U 1907+09 started to spin up with dP/dt
= -0.158 s/yr in 2004. The similarity of the pulse period histories of 4U
1907+09 and 4U 1626-26 suggests that accretion onto an oblique rotator, as
recently proposed by Perna et al., is a possible explanation for this change.


title: Baryon loading and the Weibel instability in gamma-ray bursts

abstract:
  The dynamics of two counter-streaming electron-positron-ion unmagnetized
plasma shells with zero net charge is analyzed in the context of magnetic field
generation in GRB internal shocks due to the Weibel instability. The effects of
large thermal motion of plasma particles, arbitrary mixture of plasma species
and space charge effects are taken into account. We show that, although thermal
effects slow down the instability, baryon loading leads to a non-negligible
growth rate even for large temperatures and different shell velocities, thus
guaranteeing the robustness and the occurrence of the Weibel instability for a
wide range of scenarios.


title:
Non-LTE models for synthetic spectra of type Ia supernovae/hot stars
  with extremely extended atmospheres

abstract:
  Realistic atmospheric models that link the properties and the physical
conditions of supernova ejecta to observable spectra are required for the
quantitative interpretation of observational data of type Ia supernovae (SN Ia)
and the assessment of the physical merits of theoretical supernova explosion
models. The numerical treatment of the radiation transport - yielding the
synthetic spectra - in models of SN Ia ejecta in early phases is usually
carried out in analogy to atmospheric models of `normal' hot stars. Applying
this analogy indiscriminately leads to inconsistencies in SN Ia models because
a diffusive lower boundary, while justified for hot stars, is invalid for
hydrogen and helium-deficient supernova ejecta. In type Ia supernovae the
radiation field does not thermalize even at large depths, and large optical
depths are not reached at all wavelengths. We derive an improved description of
the lower boundary that allows a more consistent solution of the radiation
transfer in SN Ia and therefore yields more realistic synthetic spectra. We
analyze the conditions that lead to a breakdown of the conventional diffusion
approximation as the lower boundary in SN Ia. For the radiative transfer, we
use a full non-LTE code originally developed for radiatively driven winds of
hot stars, with adaptations for the physical conditions in SN Ia. In addition
to a well-tested treatment of the underlying microphysical processes, this code
allows a direct comparison of the results for SN Ia and hot stars. We develop a
semi-analytical description that allows us to overcome some of the limiting
assumptions in the conventional treatment of the lower boundary in SN Ia
radiative transfer models. We achieve good agreement in a comparison between
the synthetic spectrum of our test model and an observed spectrum.


title: The M-sigma Relation for Nucleated Galaxies

abstract:
  Momentum feedback from super-Eddington accretion offers a simple explanation
for the observed M-sigma and M-M_{spheroid} relations between supermassive
black holes (SMBH) and the spheroids of their host galaxies. Recently Ferrarese
et al. and Wehner & Harris observed analogous relations between the masses of
central star clusters and their hosts. We show that stellar winds and
supernovae from such nuclear clusters (NC) give similar feedback explanations
for this case also, and we discuss the connection to the Faber-Jackson relation
for the spheroids themselves.


title:
Discovery of Extensive Optical Emission Associated with the X-ray
  Bright, Radio Faint Galactic SNR G156.2+5.7

abstract:
  We present wide-field Halpha images of the Galactic supernova remnant
G156.2+5.7 which reveal the presence of considerable faint Halpha line emission
coincident with the remnant's X-ray emission. The outermost Halpha emission
consists largely of long and thin (unresolved), smoothly curved filaments of
Balmer-dominated emission presumably associated with the remnant's forward
shock front. Patches of brighter Halpha emission along the western,
south-central, and northeastern regions appear to be radiative shocked ISM
filaments like those commonly seen in supernova remnants, with relatively
strong [O I] 6300,6364 and [S II] 6716,6731 line emissions.
  Comparison of the observed Halpha emission with the ROSAT PSPC X-ray image of
G156.2+5.7 shows that the thin Balmer-dominated filaments lie along the
outermost edge of the remnant's detected X-ray emission. Brighter radiative
emission features are not coincident with the remnant's brightest X-ray or
radio regions. Areas of sharply weaker X-ray flux seen in the ROSAT image of
G156.2+5.7 appear spatially coincident with dense interstellar clouds visible
on optical and IRAS 60 and 100 micron emission images, as well as maps of
increased optical extinction. This suggests significant X-ray absorption in
these regions due to foreground interstellar dust, especially along the western
and southern limbs. The close projected proximity and alignment of the
remnant's brighter, radiative filaments with several of these interstellar
clouds and dust lanes hint at a possible physically interaction between the
G156.2+5.7 remnant and these interstellar clouds and may indicate a smaller
distance to the remnant than previously estimated.


title: Scalar Field Dark Matter: non-spherical collapse and late time behavior

abstract:
  We show the evolution of non-spherically symmetric balls of a
self-gravitating scalar field in the Newtonian regime or equivalently an ideal
self-gravitating condensed Bose gas. In order to do so, we use a finite
differencing approximation of the Shcr\"odinger-Poisson (SP) system of
equations with axial symmetry in cylindrical coordinates. Our results indicate:
1) that spherically symmetric ground state equilibrium configurations are
stable against non-spherical perturbations and 2) that such configurations of
the SP system are late-time attractors for non-spherically symmetric initial
profiles of the scalar field, which is a generalization of such behavior for
spherically symmetric initial profiles. Our system and the boundary conditions
used, work as a model of scalar field dark matter collapse after the turnaround
point. In such case, we have found that the scalar field overdensities tolerate
non-spherical contributions to the profile of the initial fluctuation.


title: Synchrotron Radiation from Outer Space and the Chandra X-Ray Observatory

abstract:
  The universe provides numerous extremely interesting astrophysical sources of
synchrotron X radiation. The Chandra X-ray Observatory and other X-ray missions
provide powerful probes of these and other cosmic X-ray sources. Chandra is the
X-ray component of NASA's Great Observatory Program which also includes the
Hubble Space telescope, the Spitzer Infrared Telescope Facility, and the now
defunct Compton Gamma-Ray Observatory. The Chandra X-Ray Observatory provides
the best angular resolution (sub-arcsecond) of any previous, current, or
planned (for the foreseeable near future) space-based X-ray instrumentation. We
present here a brief overview of the technical capability of this X-Ray
observatory and some of the remarkable discoveries involving cosmic synchrotron
sources.


title:
The distribution of maser stars in the inner Milky Way: the effect of a
  weak, rotating bar

abstract:
  We derive the distribution of maser stars in the inner Milky Way (MW) based
on an analysis of lV-diagrams (lVd) for two samples of maser stars: 771 OH/IR
stars and 363 SiO-maser stars. They are all close to the plane of the MW and
have long. from -45 to +45deg. The two lVds are compared and found to be very
similar. They also compare well with the lVd of interstellar CO, but there are
significant differences in detail between the stellar lVds and that of the ISM.
Based on the qualitative discussion we divide the lVds into seven areas. In
each area we compare the number of stars observed with those predicted by an
assumed set of orbits in a galactic potential. This potential is axially
symmetric but a weak rotating bar has been added. We conclude that the maser
stars move on almost circular orbits outside of about 3.5 kpc, but that the
orbits become more and more elongated when one goes deep inside our MW. We find
a strong effect of the Corotation (CR) resonance (res) at 3.3 kpc, we see a
small but noticeable effect of the Outer Lindblad res at 5 kpc and no effect of
the Inner Lindblad res at r=0.8 kpc. We find a set of 6 groups of orbits that
together predict counts in agreement with the counts of stars observed. We then
calculate the trajectory of each orbit and so find the distribution of the
maser stars in the plane of the MWG. This distribution has two new (but not
unexpected) features. The first is a bar-like distribution within 2 kpc from
the GC outlined. These orbits explain the high-vel stars near l=0deg in the
forbidden and the permitted quadrants. The second feature are two
"croissant"-like voids in the distribution close to the CR radius (3.3 kpc),
which are the consequence of the presence of the CR res. We find excellent
agreement with an earlier reconstruction by Sevenster (1999).


title: Dark Matter Halos as Bose-Einstein Condensates

abstract:
  Galactic dark matter is modelled by a scalar field in order to effectively
modify Kepler's law without changing standard Newtonian gravity. In particular,
a solvable toy model with a self-interaction U(Phi) borrowed from
non-topological solitons produces already qualitatively correct rotation curves
and scaling relations. Although relativistic effects in the halo are very
small, we indicate corrections arising from the general relativistic
formulation. Thereby, we can also probe the weak gravitational lensing of our
soliton type halo. For cold scalar fields, it corresponds to a gravitationally
confined Boson-Einstein condensate, but of galactic dimensions.


title: Optical spectroscopy of the radio pulsar PSR B0656+14

abstract:
  We have obtained the spectrum of a middle-aged PSR B0656+14 in the 4300-9000
AA range with the ESO/VLT/FORS2. Preliminary results show that at 4600-7000 AA
the spectrum is almost featureless and flat with a spectral index $\alpha_nu ~
-0.2 that undergoes a change to a positive value at longer wavelengths.
Combining with available multiwavelength data suggests two wide, red and blue,
flux depressions whose frequency ratio is about 2 and which could be the 1st
and 2nd harmonics of electron/positron cyclotron absorption formed at magnetic
fields ~10^8G in upper magnetosphere of the pulsar.


title: Observed Properties of Dark Matter: dynamical studies of dSph galaxies

abstract:
  The Milky Way satellite dwarf spheroidal (dSph) galaxies are the smallest
dark matter dominated systems in the universe. We have underway dynamical
studies of the dSph to quantify the shortest scale lengths on which Dark Matter
is distributed, the range of Dark Matter central densities, and the density
profile(s) of DM on small scales. Current results suggest some surprises: the
central DM density profile is typically cored, not cusped, with scale sizes
never less than a few hundred pc; the central densities are typically 10-20
GeV/cc; no galaxy is found with a dark mass halo less massive than ~5.10^7
M_sun. We are discovering many more dSphs, which we are analysing to test the
generality of these results.


title: Non-LTE modeling of supernova-fallback disks

abstract:
  We present a first detailed spectrum synthesis calculation of a
supernova-fallback disk composed of iron. We assume a geometrically thin disk
with a radial structure described by the classical alpha-disk model. The disk
is represented by concentric rings radiating as plane-parallel slabs. The
vertical structure and emission spectrum of each ring is computed in a fully
self-consistent manner by solving the structure equations simultaneously with
the radiation transfer equations under non-LTE conditions. We describe the
properties of a specific disk model and discuss various effects on the emergent
UV/optical spectrum.
  We find that strong iron-line blanketing causes broad absorption features
over the whole spectral range. Limb darkening changes the spectral distribution
up to a factor of four depending on the inclination angle. Consequently, such
differences also occur between a blackbody spectrum and our model. The overall
spectral shape is independent of the exact chemical composition as long as iron
is the dominant species. A pure iron composition cannot be distinguished from
silicon-burning ash. Non-LTE effects are small and restricted to few spectral
features.


title: Statistical Algorithms for Identification of Astronomical X-Ray Sources

abstract:
  Observations of present and future X-ray telescopes include a large number of
serendipidious sources of unknown types. They are a rich source of knowledge
about X-ray dominated astronomical objects, their distribution, and their
evolution. The large number of these sources does not permit their individual
spectroscopical follow-up and classification. Here we use Chandra
Multi-Wavelength public data to investigate a number of statistical algorithms
for classification of X-ray sources with optical imaging follow-up. We show
that up to statistical uncertainties, each class of X-ray sources has specific
photometric characteristics which can be used for its classification. We assess
the relative and absolute performance of classification methods and measured
features by comparing the behaviour of physical quantities for statistically
classified objects with what is obtained from spectroscopy. We find that among
methods we have studied, multi-dimensional probability distribution is the best
for both classifying source type and redshift, but it needs a sufficiently
large input (learning) data set. In absence of such data, a mixture of various
methods can give a better final result. We also discuss the enhancement of
information obtained from statistical identification, and the effect of
classification method and the input set on the astronomical conclusions about
distribution and properties of the X-ray selected sources.


title: The star formation histories of galaxies in the Sloan Digital Sky Survey

abstract:
  We present the results of a MOPED analysis of ~3 x 10^5 galaxy spectra from
the Sloan Digital Sky Survey Data Release Three (SDSS DR3), with a number of
improvements in data, modelling and analysis compared with our previous
analysis of DR1. The improvements include: modelling the galaxies with
theoretical models at a higher spectral resolution of 3\AA; better calibrated
data; an extended list of excluded emission lines, and a wider range of dust
models. We present new estimates of the cosmic star formation rate, the
evolution of stellar mass density and the stellar mass function from the fossil
record. In contrast to our earlier work the results show no conclusive peak in
the star formation rate out to a redshift around 2 but continue to show
conclusive evidence for `downsizing' in the SDSS fossil record. The star
formation history is now in good agreement with more traditional instantaneous
measures. The galaxy stellar mass function is determined over five decades of
mass, and an updated estimate of the current stellar mass density is presented.
We also investigate the systematic effects of changes in the stellar population
modelling, the spectral resolution, dust modelling, sky lines, spectral
resolution and the change of data set. We find that the main changes in the
results are due to the improvements in the calibration of the SDSS data,
changes in the initial mass function and the theoretical models used.


title: The Advanced Compton Telescope Mission

abstract:
  The Advanced Compton Telescope (ACT), the next major step in gamma-ray
astronomy, will probe the fires where chemical elements are formed by enabling
high-resolution spectroscopy of nuclear emission from supernova explosions.
During the past two years, our collaboration has been undertaking a NASA
mission concept study for ACT. This study was designed to (1) transform the key
scientific objectives into specific instrument requirements, (2) to identify
the most promising technologies to meet those requirements, and (3) to design a
viable mission concept for this instrument. We present the results of this
study, including scientific goals and expected performance, mission design, and
technology recommendations.


title:
Active X-ray Optics for Generation-X, the Next High Resolution X-ray
  Observatory

abstract:
  X-rays provide one of the few bands through which we can study the epoch of
reionization, when the first galaxies, black holes and stars were born. To
reach the sensitivity required to image these first discrete objects in the
universe needs a major advance in X-ray optics. Generation-X (Gen-X) is
currently the only X-ray astronomy mission concept that addresses this goal.
Gen-X aims to improve substantially on the Chandra angular resolution and to do
so with substantially larger effective area. These two goals can only be met if
a mirror technology can be developed that yields high angular resolution at
much lower mass/unit area than the Chandra optics, matching that of
Constellation-X (Con-X). We describe an approach to this goal based on active
X-ray optics that correct the mid-frequency departures from an ideal Wolter
optic on-orbit. We concentrate on the problems of sensing figure errors,
calculating the corrections required, and applying those corrections. The time
needed to make this in-flight calibration is reasonable. A laboratory version
of these optics has already been developed by others and is successfully
operating at synchrotron light sources. With only a moderate investment in
these optics the goals of Gen-X resolution can be realized.


title:
Optical and NIR spectroscopy of Mrk1210: constraints and physical
  conditions of the active nucleus

abstract:
  Near-infrared and optical spectroscopy of the nuclear and extended emission
region of the Seyfert2 galaxy Mrk1210 is presented. This galaxy is outstanding
because it displays signatures of recent circumnuclear star formation and a
high-level of X-ray activity, in addition to the classical spectral
characteristics typical of an AGN. The NIR nuclear spectrum, which covers the
interval 0.8-2.4 microns, is dominated by HI and HeI recombination lines as
well a [SII], [SIII] and [Fe II] forbidden lines. Coronal lines of [SVIII],
[SIX], [SiVI], [SiX], and [CaVIII] in addition to molecular H_2 lines are also
detected. An estimate of the contribution of the stellar population to the
continuum is made by means of the ^{12}CO(6-3) 1.618 microns overtone bandhead.
It was found that 83% of the H-band continuum is of stellar origin. It improves
previous estimates, which claimed that at least 50% of the observed continuum
was attributed to the AGN. The analysis of the emission line profiles, both
allowed and forbidden, shows a narrower line on top of a broad blue-shifted
component. The latter seems to be associated to a nuclear outflow. This result
does not required the presence of a hidden BLR claimed to be present in
previous NIR observations of this object. Internal extinction, calculated by
means of several indicators including [FeII] flux ratios not previously used
before in AGNs, reveals a dusty AGN, while the extended regions are little or
not affected by dust. Density and temperature for the NLR are calculated using
optical and NIR lines diagnostic ratios. The results show temperatures from
10000K up to 40000K and densities between 10^3-10^5 cm^{-3}. The larger
temperatures points out that shocks must contribute to the line emission.


title: Dark matter burners: Preliminary estimates

abstract:
  We show that a star orbiting close enough to an adiabatically grown
supermassive black hole can capture a large number of weakly interacting
massive particles (WIMPs) during its lifetime. WIMP annihilation energy release
in low- to medium-mass stars is comparable with or even exceeds the luminosity
of such stars due to thermonuclear burning. The excessive energy release in the
stellar core may result in an evolution scenario different from what is
expected for a regular star. The model thus predicts the existence of unusual
stars within the central parsec of galactic nuclei. If found, such stars would
provide evidence for the existence of particle dark matter. White dwarfs seem
to be the most promising candidates to look for. The signature of a white dwarf
burning WIMPs would be a very hot star with mass and radius characteristic for
a white dwarf, but with luminosity exceeding the typical luminosity of a white
dwarf by orders of magnitude <50L_sun. A white dwarf with a highly eccentric
orbit around the central black hole may exhibit variations in brightness
correlated with the orbital phase.


title:
Fall-back crust around a quark-nova compact remnant I: The degenerate
  shell case with applications to SGRs, AXPs and XDINs

abstract:
  We explore the formation and evolution of debris ejected around quark stars
in the Quark Nova scenario, and the application to Soft Gamma-ray Repeaters
(SGRs) and Anomolous X-ray Pulsars (AXPs). If an isolated neutron star explodes
as a Quark Nova, an Iron-rich shell of degenerate matter forms out of the
fall-back (crust) material. Our model can account for many of the observed
features of SGRs and AXPs such as: (i) the two types of bursts (giant and
regular); (ii) the spin-up and spin-down episodes during and following the
bursts with associated persistant increases in $\dot{P}$; (iii) the energetics
of the boxing day burst, SGR1806$+$20; (iv) the presence of an Iron line as
observed in SGR1900$+$14; (v) the correlation between the far-Infrared and the
X-ray fluxes during the bursting episode and the quiescent phase; (vi) the hard
X-ray component observed in SGRs during the giant bursts, and (vii) the
discrepancy between the ages of SGRs/AXPs and their supernova remnants. We also
find a natural evolutionary relationship between SGRs and AXPs in our model
which predicts that only the youngest SGRs/AXPs are most likely to exhibit
strong bursting. Many features of X-ray Dim Isolated Neutron stars (XDINs) are
also accounted for in our model such as, (i) the two-component blackbody
spectra; (ii) the absorption lines around 300 eV; and (iii) the excess optical
emission.


title: The Mass-Metallicity Relation in Cosmological Hydrodynamic Simulations

abstract:
  We use cosmological hydrodynamic simulations with enriched galactic outflows
to compare predictions for the galaxy mass-metallicity (M*-Z) relation versus
observations at z~2 from Erb et al. (2006). With no outflows, galaxies are
over-enriched, indicating that outflows are required not only to suppress star
formation and enrich the IGM but also to lower galaxy metal content. The
observed M*-Z slope is matched both in our model without winds as well as our
favored outflow model where the outflow velocity scales as the escape velocity,
but is too steep in a model with constant outflow speeds. If outflows are too
widespread at early times, the IGM out of which smaller galaxies form can
become pre-polluted, resulting in a low-mass flattening of the M*-Z relation
that is inconsistent with data. Remarkably, the same momentum-driven wind model
that provides the best agreement with IGM enrichment data also yields the best
agreement with the z~2 M*-Z relation, showing the proper outflow scaling and
strength to match the observed slope and amplitude. In this model, the M*-Z
relation evolves slowly from z=6-2; an (admittedly uncertain) extrapolation to
z=0 broadly matches local M*-Z observations. Overall, the M*-Z relation
provides critical constraints on galactic outflow processes during the heydey
of star formation in the Universe.


title: Nonlinear electrodynamics and the Pioneer 10/11 spacecraft anomaly

abstract:
  The occurrence of the phenomenon known as photon acceleration is a natural
prediction of nonlinear electrodynamics (NLED). This would appear as an
anomalous frequency shift in any modeling of the electromagnetic field that
only takes into account the classical Maxwell theory. Thus, it is tempting to
address the unresolved anomalous, steady; but time-dependent, blueshift of the
Pioneer 10/11 spacecrafts within the framework of NLED. Here we show that
astrophysical data on the strength of the magnetic field in both the Galaxy and
the local (super)cluster of galaxies support the view on the major Pioneer
anomaly as a consequence of the phenomenon of photon acceleration. If
confirmed, through further observations or lab experiments, the reality of this
phenomenon should prompt to take it into account in any forthcoming research on
both cosmological evolution and origin and dynamical effects of primordial
magnetic fields, whose seeds are estimated to be very weak.


title:
The r-Process in the Proto-Neutron-Star Winds with Anisotropic Neutrino
  Emission

abstract:
  The astrophysical origin of the r-process nuclei is still unknown. Even the
most promising scenario, the neutrino-driven winds from a nascent neutron star,
encounters severe difficulties in obtaining requisite entropy and short dynamic
timescale for the r-process. In this study, the effect of anisotropy in
neutrino emission from a proto-neutron star surface is examined with
semi-analytic neutrino-driven wind models. The increase of neutrino number
density in the wind owing to the anisotropy is modeled schematically by
enhancing the effective neutrino luminosity. It is shown that the neutrino
heating rate from neutrino-antineutrino pair annihilation into
electron-positron pairs can significantly increase owing to the anisotropy and
play a dominant role for the heating of wind material. A factor of five
increase in the effective neutrino luminosity results in 50% higher entropy and
a factor of ten shorter dynamic timescale owing to this enhanced neutrino
heating. The nucleosynthesis calculations show that this change is enough for
the robust r-process, producing the third abundance peak A = 195 and beyond.
Future multi-dimensional studies with accurate neutrino transport will be
needed if such anisotropy relevant for the current scenario (more than a factor
of a few) is realized during the wind phase (~1-10 s).


title: Pushing the limit on neutron star spin rates

abstract:
  Millisecond X-ray pulsars consist of a rapidly-spinning neutron star
accreting from a low-mass stellar companion, and are the long-sought
evolutionary progenitors of millisecond radio pulsars, as well as promising
candidate sources for gravitational radiation. The population of these sources
has grown significantly over the last three years, with the discovery of six
new examples to bring the total sample to seven. Three sources are ultracompact
binaries with H-depleted donors and orbital periods of approx. 40 min, like the
185 Hz pulsar XTE J0929-314. Three more have orbital periods of 2 hr or longer,
similar to IGR J00291+5934, first detected in outburst by INTEGRAL in December
2004. The neutron star in this 2.46 hr binary has the most rapid spin of the
accreting pulsars at 599 Hz. The most recently-discovered pulsar, HETE
J1900.1-2455 (377 Hz), has an intermediate orbital period of 83.3 min, and has
been active for more than 1 yr, much longer than the typical transient
outburst. Pulsations were detected only in the first few months of the
outburst; this source has since resembled a faint, persistent non-pulsing
low-mass X-ray binary, typical of the broader low-mass X-ray binary population.


title: Evolution of emission line activity in intermediate mass young stars

abstract:
  We present optical spectra of 45 intermediate mass Herbig Ae/Be stars.
Together with the multi-epoch spectroscopic and photometric data compiled for a
large sample of these stars and ages estimated for individual stars by using
pre-main sequence evolutionary tracks, we have studied the evolution of
emission line activity in them. We find that, on average, the H_alpha emission
line strength decreases with increasing stellar age in HAeBe stars, indicating
that the accretion activity gradually declines during the PMS phase. This would
hint at a relatively long-lived (a few Myr) process being responsible for the
cessation of accretion in Herbig Ae/Be stars. We also find that the accretion
activity in these stars drops substantially by ~ 3 Myr. This is comparable to
the timescale in which most intermediate mass stars are thought to lose their
inner disks, suggesting that inner disks in intermediate mass stars are
dissipated rapidly after the accretion activity has fallen below a certain
level. We, further find a relatively tight correlation between strength of the
emission line and near-infrared excess due to inner disks in HAeBe stars,
indicating that the disks around Herbig Ae/Be stars cannot be entirely passive.
We suggest that this correlation can be understood within the frame work of the
puffed-up inner rim disk models if the radiation from the accretion shock is
also responsible for the disk heating.


title: Stellar archaeology: the evolving spectrum of FG Sge

abstract:
  Over an interval of 120 years, the extraordinary object FG Sge has been
transformed from a hot post-AGB star to a very luminous cool supergiant.
Theoretically, this evolution has been associated with the reignition of a
helium-shell during the post-AGB stage. A series of studies of the chemical
composition of the photosphere have suggested that this evolution has been
associated with a dramatic increase of approximately 3 dex in the abundances of
s-process elements between about 1960 and 1995. The problem with this apparent
change is that it occurred at a time when the surface convection zone, which is
governed by the star's effective temperature, could not have developed
sufficiently to dredge processed material from the stellar interior to the
surface. We have reviewed the chemical evolution of FG Sge by means of
modelling the time-varying spectrum under a range of assumptions. By comparing
these models with published observational data, a self-consistent picture has
emerged. In particular we find that surface hydrogen has been depleted during
the interval in question. In contrast, the s-process abundances have generally
maintained a steady enhancement of around 1 - 2 dex, although some modest
changes may have occurred since 1950. This implies that FG Sge has not just
completed dredging up freshly-produced s-process isotopes. However, there
remains a contradiction between the observed hydrogen-depletion, the age of the
associated planetary nebula, and current evolutionary models for a pre-white
dwarf suffering a late thermal pulse.


title: Neutrino pair annihilation near accreting, stellar-mass black holes

abstract:
  We investigate the energy-momentum deposition due to neutrino-antineutrino
annihilation in the vicinity of axisymmetric, accreting black holes (BHs) by
numerically ray-tracing neutrino trajectories in a Kerr space-time.
Hyperaccreting stellar-mass BHs are widely considered as energy sources that
can drive ultrarelativistic outflows with the potential to produce gamma-ray
bursts. In contrast to earlier works, we provide an extensive and detailed
parameter study of the influence of general relativistic (GR) effects and of
different neutrinosphere geometries. These include idealized thin disks, tori,
and spheres, or are constructed as non-selfgravitating equilibrium matter
distributions for varied BH rotation. Considering isothermal neutrinospheres
with the same temperature and surface area, we confirm previous results that
compared to Newtonian calculations, GR effects increase the annihilation rate
measured by an observer at infinity by a factor of 2 when the neutrinosphere is
a disk. However, in case of a torus and a sphere the influence of GR effects is
globally only ~25%, although locally it can be significantly larger.
Independent of whether GR effects are included, disks yield the highest energy
deposition rates, followed by tori and, with the lowest rates, spheres. For
disks and tori, increasing the angular momentum of the BH from 0 to 1 enhances
the energy deposition rate measured by an observer at infinity by roughly a
factor of 2 due to the shrinking inner radius of the neutrinosphere. (abridged)


title:
The structural and photometric properties of early-type galaxies in
  hierarchical models

abstract:
  We present predictions for the structural and photometric properties of
early-type galaxies in the cold dark matter cosmology from the published
semi-analytical galaxy formation models of Baugh et al. and Bower et al. These
calculations were made with the GALFORM code, which tracks the evolution of the
disc and bulge components of a galaxy, using a self-consistent model to compute
the scalelengths. The sizes of galactic discs are determined by the
conservation of the angular momentum of cooling gas. The sizes of merger
remnants are computed by applying the virial theorem and conserving the binding
energy of the progenitors and their orbital energy. We compare the model
predictions with observational results derived from the SDSS. The model enjoys
a number of notable successes, such as giving reasonable reproductions of the
local Faber-Jackson relation, the velocity dispersion-age relation, and the
fundamental plane relating the luminosity, velocity dispersion and effective
radius of spheroids. These achievements are all the more remarkable when one
bears in mind that none of the parameters have been adjusted to refine the
model predictions. We study how the residuals around the fundamental plane
relation depend on galaxy properties. We examine in detail the physical
ingredients of the calculation of galaxy sizes. We also study the evolution of
the scaling relations with redshift. However, there are some important
disagreements between the predictions of the model and observations: the
brightest model spheroids have effective radii smaller than observed and the
zero-point of the fundamental plane shows little or no evolution with redshift
in the model.


title:
Comparing dynamical and photometric-stellar masses of early-type
  galaxies at z ~ 1

abstract:
  The purpose of this study is to explore the relationship between galaxy
stellar masses, based on multiwavelength photometry spectral template fitting
and dynamical masses based on published velocity dispersion measurements, for a
sample of 48 early-type galaxies at z ~ 1 with HST/ACS morphological
information. We determine photometric-stellar masses and perform a quantitative
morphological analysis of cluster and field galaxies at redshift 0.6 < z < 1.2,
using ground- and space-based multiwavelegth data available on the GOODS-S
field and on the field around the X-ray luminous cluster RDCS1252.9-2927 at z =
1.24. We use multi-band photometry over 0.4-8um from HST/ACS, VLT/ISAAC and
Spitzer/IRAC to estimate photometric-stellar masses using Composite Stellar
Population (CSP) templates computed with PEGASE.2 models. We compare stellar
masses with those obtained using CSPs built with Bruzual & Charlot and Maraston
models. We then compare photometric-stellar mass and dynamical mass estimates
as a function of morphological parameters obtained from HST/ACS imaging. Based
on our sample, which spans the mass range log(Mphot)=[10, 11.5], we find that
1) PEGASE.2, BC03, M05 yield consistent photometric-stellar masses for
early-type galaxies at z ~ 1 with a small scatter (0.15 dex rms); 2) adopting a
Kroupa IMF, photometric-stellar masses match dynamical mass estimates for
early-type galaxies with an average offset of 0.27 dex; 3) assuming a costant
IMF, increasing dark matter fraction with the increasing galaxy mass can
explain the observed trend.


title: The Formation of Brown Dwarfs: Observations

abstract:
  We review the current state of observational work on the formation of brown
dwarfs, focusing on their initial mass function, velocity and spatial
distributions at birth, multiplicity, accretion, and circumstellar disks. The
available measurements of these various properties are consistent with a common
formation mechanism for brown dwarfs and stars. In particular, the existence of
widely separated binary brown dwarfs and a probable isolated proto-brown dwarf
indicate that some substellar objects are able to form in the same manner as
stars through unperturbed cloud fragmentation. Additional mechanisms such as
ejection and photoevaporation may play a role in the birth of some brown
dwarfs, but there is no observational evidence to date to suggest that they are
the key elements that make it possible for substellar bodies to form.