title: Galactic foreground contribution to the BEAST CMB Anisotropy Maps

abstract:
  We report limits on the Galactic foreground emission contribution to the
Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB
anisotropy maps. We estimate the contribution from the cross-correlations
between these maps and the foreground emission templates of an H${\alpha}$ map,
a de-striped version of the Haslam et al. 408 MHz map, and a combined 100
$\mu$m IRAS/DIRBE map. Our analysis samples the BEAST $\sim10^\circ$
declination band into 24 one-hour (RA) wide sectors with $\sim7900$ pixels
each, where we calculate: (a) the linear correlation coefficient between the
anisotropy maps and the templates; (b) the coupling constants between the
specific intensity units of the templates and the antenna temperature at the
BEAST frequencies and (c) the individual foreground contributions to the BEAST
anisotropy maps. The peak sector contributions of the contaminants in the
Ka-band are of 56.5% free-free with a coupling constant of $8.3\pm0.4$
$\mu$K/R, and 67.4% dust with $45.0\pm2.0$ $\mu$K/(MJy/sr). In the Q-band the
corresponding values are of 64.4% free-free with $4.1\pm0.2$ $\mu$K/R and 67.5%
dust with $24.0\pm1.0$ $\mu$K/(MJy/sr). Using a lower limit of 10% in the
relative uncertainty of the coupling constants, we can constrain the sector
contributions of each contaminant in both maps to $< 20$% in 21 (free-free), 19
(dust) and 22 (synchrotron) sectors. At this level, all these sectors are found
outside of the $\mid$b$\mid = 14.6^\circ$ region. By performing the same
correlation analysis as a function of Galactic scale height, we conclude that
the region within $b=\pm17.5^{\circ}$ should be removed from the BEAST maps for
CMB studies in order to keep individual Galactic contributions below $\sim 1$%
of the map's rms.


title:
Distance of three Supernova Remnants from HI line observations in a
  complex region: G114.3+0.3, G116.5+1.1, and CTB 1 (G116.9+0.2)

abstract:
  We present new radio continuum and HI images towards the supernova remnants
(SNRs) G114.3+0.3, G116.5+1.1, and G116.9+0.2 (CTB 1) taken from the Canadian
Galactic Plane Survey (CGPS). We discuss the dynamics of their HI environment
and a possible relationship of these SNRs with each other. We discovered
patches of HI emission surrounding G114.3+0.3 indicating a location in the
Local arm at a distance of about 700 pc in contrast to previous publications
which proposed a Perseus arm location. The other two SNRs have radial
velocities of -17 km/s (G116.5+1.1) and -27 km/s (CTB 1) according to related
HI. However, the structure of the HI and its dynamics in velocity space suggest
a possible relation between them, placing both remnants at a distance of about
1.6 kpc. CTB 1 appears to be embedded in an HI feature which is moving as a
whole towards us with a velocity of about 10 km/s. Furthermore, the
off-centered location of CTB 1 in a large HI bubble indicates that the
so-called breakout region of the remnant is in fact due to its expansion
towards the low density interior of this bubble. We believe that the progenitor
star of CTB 1 was an early B or O-type star shaping its environment with a
strong stellar wind in which case it exploded in a Ib or Ic event.


title: Mapping inspiral rates on population synthesis parameters

abstract:
  Formation rates of compact-object binaries are often derived from population
synthesis calculations. However, such calculations depend sensitively on a
relatively large number of model input parameters. Given considerable
uncertainty in those model parameters, the predicted inspiral rates for double
compact objects relevant to gravitational-wave interferometric detectors have
been shown to be are uncertain by several orders of magnitude. Typically,
inspiral rates are estimated for only a small set of models with a remarkably
poor coverage of the highly multi-dimensional parameter space (primarily
because of limited computer resources). Here, using as an example seven
population-synthesis model parameters, we show that it is possible to derive
fits of double-compact-object inspiral rates dependent simultaneously on all
seven parameters. We find these fits to be accurate to 50% for binary black
holes and to 40% for binary neutron stars. The availability of such fits
implies that (i) depending on the problem of interest, it is not necessary to
complete large numbers of computationally demanding population synthesis
calculations; and (ii) for the first time, the sufficient exploration of the
relevant phase space and the assessment of the uncertainties involved is not
limited by computational resources and becomes feasible. Finally, we have also
produced a histogram of the (a priori likely) binary black hole inpsiral rate,
assuming our population synthesis models are equally likely. This histogram,
effectively an a priori probability distribution for the BH-BH inspiral rate,
suggests that merger rate is conservatively bounded below by
10^(-8)/yr/Milky-Way-galaxy.


title: Magneto-driven Shock Waves in Core-Collapse Supernova

abstract:
  We perform a series of two-dimensional magnetohydrodynamic simulations of the
rotational core-collapse of a magnetized massive star. We employ a realistic
equation of state and take into account the neutrino cooling by the so-called
leakage scheme. In this study we systematically investigate how the strong
magnetic field and the rapid rotation affect the propagation of the shock
waves. Our results show that in the case of the strong initial poloidal
magnetic field, the toroidal magnetic field amplified by the differential
rotation, becomes strong enough to generate a tightly collimated shock wave
along the rotational axis. On the other hand, in the case of the weak initial
magnetic field, although the differential rotation amplifies toroidal magnetic
field over the long rotational period, the launched shock wave is weak and the
shape of it becomes wider. The former case is expected to be accompanied by the
formation of the so-called magnetar. Our models with rapid rotation and strong
magnetic field can create a nozzle formed by the collimated shock wave. This
might be the analogous situation of the collapsar that is plausible for the
central engine of the Gamma-Ray Bursts.


title:
The Hamburg/ESO R-process Enhanced Star survey (HERES). I. Project
  description, and discovery of two stars with strong enhancements of
  neutron-capture elements

abstract:
  We report on a dedicated effort to identify and study metal-poor stars
strongly enhanced in r-process elements ([r/Fe] > 1 dex; hereafter r-II stars),
the Hamburg/ESO R-process Enhanced Star survey (HERES). Moderate-resolution
(~2A) follow-up spectroscopy has been obtained for metal-poor giant candidates
selected from the Hamburg/ESO objective-prism survey (HES) as well as the HK
survey to identify sharp-lined stars with [Fe/H] < -2.5dex. For several hundred
confirmed metal-poor giants brighter than B~16.5mag (most of them from the
HES), ``snapshot'' spectra (R~20,000; S/N~30 per pixel) are being obtained with
VLT/UVES, with the main aim of finding the 2-3% r-II stars expected to be among
them. These are studied in detail by means of higher resolution and higher S/N
spectra. In this paper we describe a pilot study based on a set of 35 stars,
including 23 from the HK survey, 8 from the HES, and 4 comparison stars. We
discovered two new r-II stars, CS29497-004 ([Eu/Fe] = 1.64 +/- 0.22) and
CS29491-069 ([Eu/Fe] = 1.08 +/- 0.23). A first abundance analysis of
CS29497-004 yields that its abundances of Ba to Dy are on average enhanced by
1.5dex with respect to iron and the Sun and match a scaled solar r-process
pattern well, while Th is underabundant relative to that pattern by 0.3dex,
which we attribute to radioactive decay. That is, CS29497-004 seems not to
belong to the class of r-process enhanced stars displaying an ``actinide
boost'', like CS31082-001 (Hill et al. 2002), or CS30306-132 (Honda et al.
2004b). The abundance pattern agrees well with predictions of the
phenomenological model of Qian & Wasserburg.


title: Accelerated planetesimal growth in self-gravitating protoplanetary discs

abstract:
  In this paper we consider the evolution of small planetesimals in marginally
stable, self-gravitating protoplanetary discs. The drag force between the disc
gas and the embedded planetesimals generally causes the planetesimals to drift
inwards through the disc at a rate that depends on the particle size. In a
marginally stable, self-gravitating disc, however, the planetesimals are
significantly influenced by the non-axisymmetric spiral structures resulting
from the growth of the gravitational instability. For small particles, that are
strongly coupled to the disc gas, and for large particles, that have
essentially decoupled from the disc gas, the effect is not particularly
significant. Intermediate sized particles, which would generally have the
largest radial drift rates, do, however, become significantly concentrated at
the peaks of the spiral arms. These high density regions may persist for, of
order, an orbital period and may attain densities comparable to that of the
disc gas. Although at the end of the simulation only ~ 25 % of the planetesimal
particles lie in regions of enhanced density, during the course of the
simulation at least 75 % of the planetesimal particles have at some stage been
in a such a region. We find that the concentration of particles in the spiral
arms results in an increased collision rate, an effect that could significantly
accelerate planetesimal growth. The density enhancements may also be sufficient
for the growth of planetesimals through direct gravitational collapse. The
interaction between small planetesimals and self-gravitating spiral structures
may therefore play an important role in the formation of large planetesimals
that will ultimately coagulate to form terrestrial planets or the cores of
gas/ice giant planets.


title:
Deep Hubble Space Telescope/ACS Observations of I Zw 18: a Young Galaxy
  in Formation

abstract:
  We present V and I photometry of the resolved stars in the most
metal-deficient blue compact dwarf galaxy known, I Zw 18 (Zsun/50), using
Hubble Space Telescope/Advanced Camera for Surveys (ACS) images, the deepest
ones ever obtained for this galaxy. The resulting I vs. V-I color-magnitude
diagram (CMD) reaches limiting magnitudes V=I=29 mag. It reveals a young
stellar population of blue main-sequence (MS) stars (age <30 Myr) and blue and
red supergiants (10 Myr<age<100 Myr), but also an older evolved population of
asymptotic giant branch (AGB) stars (100 Myr<age<500 Myr). We derive a distance
to I Zw 18 in the range 12.6 Mpc - 15 Mpc from the brightness of its AGB stars,
with preferred values in the higher range. The red giant branch (RGB) stars are
conspicuous by their absence, although, for a distance of I Zw 18 <15 Mpc, our
imaging data go ~ 1-2 mag below the tip of the RGB. Thus, the most evolved
stars in the galaxy are not older than 500 Myr and I Zw 18 is a bona fide young
galaxy. Several star formation episodes can be inferred from the CMDs of the
main body and the C component. There have been respectively three and two
episodes in these two parts, separated by periods of ~ 100-200 Myr. In the main
body, the younger MS and massive post-MS stars are distributed over a larger
area than the older AGB stars, suggesting that I Zw 18 is still forming from
the inside out. In the C component, different star formation episodes are
spatially distinct, with stellar population ages decreasing from the northwest
to the southeast, also suggesting the ongoing build-up of a young galaxy.


title:
Deep VLT spectroscopy of the blue compact dwarf galaxies Tol 1214-277
  and Tol 65

abstract:
  We present VLT spectroscopic observations with different spectral resolutions
and different slit orientations of the two metal-deficient blue compact dwarf
(BCD) galaxies Tol 1214-277 and Tol 65. The oxygen abundances in the brightest
HII regions of Tol 1214-277 and Tol 65 are found to be 12+log O/H = 7.55+/-0.01
and 7.54+/-0.01, or Zsun/24. The nitrogen-to-oxygen abundance ratios in the two
galaxies are log N/O =-1.64+/-0.03 and -1.60+/-0.02 and lie in the narrow range
found for other most metal-deficient BCDs. The helium mass fraction derived in
several HII regions in both galaxies is consistent with a high primordial
helium mass fraction, Yp ~ 0.244. We confirm the detection of the
high-ionization forbidden emission line [FeV]4227 in the spectrum of Tol
1214-277. Additionally, weak [NeIV]4725, [FeVI]5146, 5177, and [FeVII]5721,
6087 emission lines are detected in the high-resolution spectrum of Tol
1214-277. The detection of these lines implies the presence of hard radiation
with photon energy in the range ~ 4-8 Ryd. Emission lines are detected in the
spectra of eight galaxies in the fields of Tol 1214-277 and Tol 65. Seven of
these galaxies are background objects, while one galaxy has a redshift close to
that of Tol 1214-277. Situated at a projected distance of ~ 14.5 kpc from Tol
1214-277, this galaxy is probably a companion of the BCD.


title: Pox 186: an ultracompact galaxy with dominant ionized gas emission

abstract:
  We present a ground-based optical spectroscopic and HST U, V, I photometric
study of the blue compact dwarf (BCD) galaxy Pox 186. It is found that the
emission of the low-surface brightness (LSB) component in Pox 186 at radii <
3'' (< 270 pc in linear scale) is mainly gaseous in origin. We detect Halpha
emission out to radii as large as 6''. At radii > 3'' the light of the LSB
component is contaminated by the emission of background galaxies complicating
the study of the outermost regions. The surface brightness distribution in the
LSB component can be approximated by an exponential law with a scale length
alpha < 120 pc. This places Pox 186 among the most compact dwarf galaxies
known. The derived alpha is likely to be an upper limit to the scale length of
the LSB component because of the strong contribution of the gaseous emission.
The oxygen abundance in the bright HII region derived from the 4.5m Multiple
Mirror Telescope (MMT) and 3.6m ESO telescope spectra are 12+log(O/H)=
7.76+/-0.02 and 7.74+/-0.01 (~ Zsun/15), respectively, in accordance with
previous determinations. The helium mass fractions found in this region are
Y=0.248+/-0.009 (MMT) and Y=0.248+/-0.004 (3.6m) suggesting a high primordial
helium abundance.


title: Nuclear Reaction Rates and Carbon Star Formation

abstract:
  We have studied how the third dredge-up and the carbon star formation in
low-mass Asymptotic Giant Branch stars depends on certain key nuclear reaction
rates. We find from a set of complete stellar evolution calculations of a 2Msun
model with Z=0.01 including mass loss, that varying either the N14(p,g)O15 or
the 3-alpha reaction rate within their uncertainties as given in the NACRE
compilation results in dredge-up and yields that differ by a factor of 2. Model
tracks with a higher rate for the 3-alpha rate and a lower rate for the
N14(p,g)O15 reaction both show more efficient third dredge-up. New experimental
results for the N14(p,g)O15 reaction rates are surveyed, yielding a rate which
is about 40% lower than the tabulated NACRE rate, and smaller than NACRE's
lower limit. We discuss the possible implications of the revised nuclear
reaction stellar evolution calculations that aim to reproduce the observed
carbon star formation at low mass, which requires efficient third dredge-up.


title: Molecular Hydrogen Kinematics in Cepheus A

abstract:
  We present the radial velocity structure of the molecular hydrogen outflows
associated to the star forming region Cepheus A. This structure is derived from
doppler shift of the H_2 v=1-0 S(1) emission line obtained by Fabry-Perot
spectroscopy. The East and West regions of emission, called Cep A(E) and Cep
A(W), show radial velocities in the range -20 to 0 km/s with respect to the
molecular cloud. Cep A(W) shows an increasing velocity with position offset
from the core indicating the existence of a possible accelarating machanism.
Cep A(E) has an almost constant mean radial velocity of -18 km/s along the
region although with a large dispersion in velocity, indicating the possibility
of a turbulent outflow. A detailed analysis of the Cep A(E) region shows
evidence for the presence of a Mach disk on that outflow. Also, we argue that
the presence of a velocity gradient in Cep A(W) is indicative of a C-shock in
this region. Following Riera et al. (2003), we analyzed the data using wavelet
analysis to study the line width and the central radial velocity distributions.
We found that both outflows have complex spatial and velocity structures
characteristic of a turbulent flow.


title:
Gemini/GMOS Imaging of Globular Clusters in the Virgo Galaxy NGC 4649
  (M60)

abstract:
  We present Sloan g and i imaging from the GMOS instrument on the Gemini North
telescope for the globular cluster (GC) system around the Virgo galaxy NGC 4649
(M60). Our three pointings, taken in good seeing conditions, cover an area of
about 90 sq. arcmins. We detect 2,151 unresolved sources. Applying colour and
magnitude selection criteria to this source list gives 995 candidate GCs that
is greater than 90% complete to a magnitude of i = 23.6, with little
contamination from background galaxies. We find fewer than half a dozen
potential Ultra Compact Dwarf galaxies around NGC 4649. Foreground extinction
from the nearby spiral NGC 4647 is limited to be A_V < 0.1. We confirm the
bimodality in the GC colour distribution found by earlier work using HST/WFPC2
imaging. As is commonly seen in other galaxies, the red GCs are concentrated
towards the centre of the galaxy, having a steeper number density profile than
the blue GC subpopulation. The varying ratio of red-to-blue GCs with radius can
largely explain the overall GC system colour gradient. The underlying galaxy
starlight has a similar density profile slope and colour to the red GCs. This
suggests a direct connection between the galaxy field stars and the red GC
subpopulation. We estimate a total GC population of 3700 +/- 900, with the
uncertainty dominated by the extrapolation to larger radii than observed. This
total number corresponds to a specific frequency S_N = 4.1 +/- 1.0. Future work
will present properties derived from GMOS spectra of the NGC 4649 GCs.


title:
Carbon and Oxygen Galactic Gradients: Observational Values from HII
  Region Recombination Lines

abstract:
  We present results of deep echelle spectrophotometry of eight Galactic HII
regions located at Galactocentric distances between 6.3 and 10.4 kpc. The data
have been taken with the Very Large Telescope (VLT) Ultraviolet Echelle
Spectrograph (UVES) in the 3100 to 10360 A range. We have derived C++ and O++
abundances from recombination lines for all the objects, as well as O+
abundances from this kind of lines for three of the nebulae. The intensity of
recombination lines is almost independent of the assumed electron temperature
as well as of the possible presence of spatial temperature variations or
fluctuations inside the nebulae. These data allow the determination of the
gas-phase C and O abundance gradients of the Galactic disk, of paramount
importance for chemical evolution models. This is the first time the C gradient
is derived from such a large number of HII regions and for such a wide range of
Galactocentric distances. Abundance gradients are found of the form
$\Delta$log(O/H) = -0.044$\pm$0.010 dex kpc^-1, $\Delta$log(C/H) =
-0.103$\pm$0.018 dex kpc^-1, and $\Delta$log(C/O) = -0.058$\pm$0.018 dex
kpc^-1.


title:
Carbon Nitrogen, and Oxygen Galactic Gradients: A Solution to the Carbon
  Enrichment Problem

abstract:
  Eleven models of Galactic chemical evolution, differing in the carbon,
nitrogen,and oxygen yields adopted, have been computed to reproduce the
Galactic O/H values obtained from H II regions. All the models fit the oxygen
gradient, but only two models fit also the carbon gradient, those based on
carbon yields that increase with metallicity due to stellar winds in massive
stars (MS) and decrease with metallicity due to stellar winds in low and
intermediate mass stars (LIMS). The successful models also fit the C/O versus
O/H evolution history of the solar vicinity obtained from stellar observations.
We also compare the present day N/H gradient and the N/O versus O/H and the
C/Fe, N/Fe, O/Fe versus Fe/H evolution histories of the solar vicinity
predicted by our two best models with those derived from H II regions and from
stellar observations. While our two best models fit the C/H and O/H gradients
as well as the C/O versus O/H history, only Model 1 fits well the N/H gradient
and the N/O values for metal poor stars but fails to fit the N/H values for
metal rich stars. Therefore we conclude that our two best models solve the C
enrichment problem, but that further work needs to be done on the N enrichment
problem. By adding the C and O production since the Sun was formed predicted by
Models 1 and 2 to the observed solar values we find an excellent agreement with
the O/H and C/H values of the solar vicinity derived from H II regions O and C
recombination lines. One of the most important results of this paper is that
the fraction of carbon due to MS and LIMS in the interstellar medium is
strongly dependent on time and on the galactocentric distance; at present about
half of the carbon in the interstellar medium of the solar vicinity has been
produced by MS and half by LIMS.


title:
MGGPOD: a Monte Carlo Suite for Modeling Instrumental Line and Continuum
  Backgrounds in Gamma-Ray Astronomy

abstract:
  Intense and complex instrumental backgrounds, against which the much smaller
signals from celestial sources have to be discerned, are a notorious problem
for low and intermediate energy gamma-ray astronomy (~50 keV - 10 MeV).
Therefore a detailed qualitative and quantitative understanding of instrumental
line and continuum backgrounds is crucial for most stages of gamma-ray
astronomy missions, ranging from the design and development of new
instrumentation through performance prediction to data reduction. We have
developed MGGPOD, a user-friendly suite of Monte Carlo codes built around the
widely used GEANT (Version 3.21) package, to simulate ab initio the physical
processes relevant for the production of instrumental backgrounds. These
include the build-up and delayed decay of radioactive isotopes as well as the
prompt de-excitation of excited nuclei, both of which give rise to a plethora
of instrumental gamma-ray background lines in addition to continuum
backgrounds. The MGGPOD package and documentation are publicly available for
download from http://sigma-2.cesr.fr/spi/MGGPOD/.
  We demonstrate the capabilities of the MGGPOD suite by modeling high
resolution gamma-ray spectra recorded by the Transient Gamma-Ray Spectrometer
(TGRS) on board Wind during 1995. The TGRS is a Ge spectrometer operating in
the 40 keV to 8 MeV range. Due to its fine energy resolution, these spectra
reveal the complex instrumental background in formidable detail, particularly
the many prompt and delayed gamma-ray lines. We evaluate the successes and
failures of the MGGPOD package in reproducing TGRS data, and provide
identifications for the numerous instrumental lines.


title:
The broad-band X-ray spectrum of the dipping Low Mass X-ray Binary
  EXO0748--676

abstract:
  We present results of a 0.1-100 keV BeppoSAX observation of the dipping LMXRB
EXO 0748-676 performed in 2000 November. During the observation the source
exhibited X-ray eclipses, type I X-ray bursts and dipping activity over a wide
range of orbital phases. The 0.1-100keV "dip-free"(ie. dipping and eclipsing
intervals excluded) spectrum is complex,especially at low-energies where a soft
excess is present. Two very different spectral models give satisfactory fits.
The first is the progressive covering model, consisting of separately absorbed
black body and cut-off power-law components.The second model is an absorbed
cut-off power-law together with a moderately ionized absorber with a sub-solar
abundance of Fe and a 2.13 keV absorption feature (tentatively identified with
Si xiii). This ionized absorber may be the same feature as seen by Chandra
during dips from EXO 0748-676.


title: Early phases of different types of isolated neutron star

abstract:
  Two Galactic isolated strong X-ray pulsars seem to be in the densest
environments compared to other types of Galactic pulsar. X-ray pulsar
J1846-0258 can be in an early phase of anomalous X-ray pulsars and soft gamma
repeaters if its average braking index is ~1.8-2.0. X-ray pulsar J1811-1925
must have a very large average braking index (n~11) if this pulsar was formed
by SN 386AD. This X-ray pulsar can be in an early phase of evolution of the
radio pulsars located in the region P~50-150 ms and \.{P}~10$^{-14}-10^{-16}$
s/s of the P-\.{P} diagram. X-ray/radio pulsar J0540-69 seems to be evolving in
the direction to the dim isolated thermal neutron star region on the P-\.{P}
diagram. Possible progenitors of different types of neutron star are also
discussed.


title:
Intermediate Mass Black Holes in Accreting Binaries: Formation,
  Evolution and Observational Appearance

abstract:
  We study the origin of the ultraluminous X-ray source M82-X1 in the nearby
starburst galaxy M82. This X-ray source is of particular interest as it is
currently the best candidate intermediate mass black hole; it is associated
with a 54mHz quasi periodic oscillations with a relatively low (~1keV)
black-body temperature.
  We perform detailed binary evolution calculations of 2--15Msun stars which
transfer mass to a 100--2000Msun black hole and present an empirical model for
the X-ray characteristics expected for such binaries. Based on the binary
evolution calculations and the assumption in our simulations we conclude that
the most likely candidate for the bright X-ray source M82-X1 is a 10-15Msun
star near the end of its main-sequence or slightly evolved, which transfers
mass to a ~1000Msun black hole. We expect the system to be in the high/soft
state. In that case the binary will not be visible as a source of gravitational
wave radiation, but other transient X-ray binaries with lower mass donors way
be rather bright sources of gravitational wave radiation.


title:
An extreme, blueshifted iron line profile in the Narrow Line Seyfert 1
  PG 1402+261; an edge-on accretion disk or highly ionized absorption?

abstract:
  We report on a short XMM-Newton observation of the radio-quiet Narrow Line
Seyfert 1 PG 1402+261. The EPIC X-ray spectrum of PG 1402+261 shows a strong
excess of counts between 6-9 keV in the rest frame. This feature can be modeled
by an unusually strong (equivalent width 2 keV) and very broad (FWHM velocity
of 110000 km/s) iron K-shell emission line. The line centroid energy at 7.3 keV
appears blue-shifted with respect to the iron Kalpha emission band between
6.4-6.97 keV, while the blue-wing of the line extends to 9 keV in the quasar
rest frame. The line profile can be fitted by reflection from the inner
accretion disk, but an inclination angle of >60 deg is required to model the
extreme blue-wing of the line. Furthermore the extreme strength of the line
requires a geometry whereby the hard X-ray emission from PG 1402+261 above 2
keV is dominated by the pure-reflection component from the disk, while little
or none of the direct hard power-law is observed. Alternatively the spectrum
above 2 keV may instead be explained by an ionized absorber, if the column
density is sufficiently high (N_H > 3 x 10^23 cm^-2) and if the matter is
ionized enough to produce a deep (tau~1) iron K-shell absorption edge at 9 keV.
This absorber could originate in a large column density, high velocity outflow,
perhaps similar to those which appear to be observed in several other high
accretion rate AGN. Further observations, especially at higher spectral
resolution, are required to distinguish between the accretion disk reflection
or outflow scenarios.


title:
Comparing the properties of local globular cluster systems: implications
  for the formation of the Galactic halo

abstract:
  (Abridged) We investigate the hypothesis that some fraction of the globular
clusters presently observed in the Galactic halo formed in external dwarf
galaxies, by means of a detailed comparison between Zinn's "old halo", "young
halo", and "bulge/disk" sub-systems and the globular clusters in local dwarf
galaxies. The Galactic sub-systems possess distinct spatial and age
distributions, age-metallicity relationships, and orbital parameters, although
we observe some OH clusters with ages and orbits more similar to those of YH
objects. Almost all Galactic globulars with large core radii (r_c) fall into
the YH sub-system, while the OH and BD ensembles are characterized by compact
clusters. The majority of the external clusters are indistinguishable from the
Galactic YH objects in terms of HB morphology, but 20-30% of external clusters
have HB morphologies most similar to the Galactic OH clusters. In addition, the
external clusters have an r_c distribution which very closely matches that for
the YH objects. The old halo r_c distribution can be very well represented by a
composite distribution formed from 83-85% of objects with structures typical of
BD clusters, and 15-17% of objects with structures typical of external
clusters. Taken together our results fully support the accretion hypothesis. We
conclude that all 30 YH clusters and 15-17% of the OH clusters (10-12 objects)
are of external origin. The Galaxy may therefore have experienced ~7 merger
events with cluster-bearing dSph-type galaxies during its lifetime, building up
45-50% of the mass of the stellar halo. Finally, we identify a number of OH
objects which have properties characteristic of accreted clusters. Several of
the clusters associated with the recently proposed CMa dwarf fall into this
category.


title: Small-Scale Structure, Missing Galaxies and Gravitational Lensing

abstract:
  The gravitational lensing constraints on the small mass end of the LCDM mass
function are discussed. Here a conservative approach is taken where only the
most difficult to explain image flux anomalies in strong QSO lenses are
emphasized. Numerical simulations are performed to compare predictions for the
LCDM small scale mass function with the observed flux ratios. It is found that
the cusp caustic lens anomalies and the disagreements between monochromatic
flux ratios and simple lens models can be explained without any substructure in
the primary lenses' dark matter halos. Extragalactic LCDM halos of mass < 10^9
Msun are enough to naturally explain these anomalies. This does not mean that
substructure within the host lens is not contributing. In fact, it could
dominate the lensing depending on how much of substructure survives in the
centers of galactic halos.
  Spectroscopic gravitational lensing provides more information on the nature
of these substructures. Thus far, the one relevant case in which this technique
has been used, observations of Q2237+0305, shows evidence of more small mass
halos (~ 10^6 Msun$) than is expected in the LCDM model.


title: Gamma-Ray All Sky Imaging with BATSE

abstract:
  The BATSE mission aboard CGRO observed the whole sky for 9 years in the 20
keV - 2 MeV energy band. Flat-fielding of the temporal variations in the
background present in the data set has been accomplished through a GEANT3
Monte-Carlo simulation - the BATSE Mass Model (BAMM). The Earth Occultation
technique (EOT) is used together with a maximum-likelihood imaging approach to
construct all-sky maps with ~mCrab sensitivity. Additionally, a non-linear
CLEAN algorithm is applied to the all-sky maps to remove large artefacts that
are systematic of the EOT. The latest survey results produced through the
application of this technique to a subset of the BATSE data set are presented.


title:
The optical/NIR counterpart of the INTEGRAL obscured source IGR
  J16318-4848 : a sgB[e] in a HMXB ?

abstract:
  The X-ray source IGR J16318-4848 was the first source discovered by INTEGRAL.
The high energy spectrum exhibits such a high column density that the source is
undetectable in X-rays below 2 keV. We used the NTT telescope of ESO to obtain
optical and near-infrared (NIR) observations. We confirm the already proposed
NIR counterpart and for the first time extended detection into optical. We
report here photometric measurements in the R, I, J, bands, upper flux limits
in the Bb and V bands, lower flux limits in the H and Ks bands. We also obtain
NIR spectroscopy, revealing a large number of emission lines, including
forbidden iron lines and P-Cygni profiles, and showing a strong similarity with
CI Cam, another strongly absorbed source. These data point to a high
luminosity, high temperature source, with an intrinsic optical-NIR absorption
greater than the interstellar absorption, but two orders of magnitude below the
X-ray absorption. We propose that the source is a High Mass X-ray binary (HMXB)
at a distance between 0.9 and 6.2 kpc, the optical/NIR counterpart corresponds
to the mass donor, which is an early-type star, maybe a sgB[e] star, surrounded
by a dense and absorbing circumstellar material. This would make the second
HMXB with a sgB[e] star as the mass donor after CI Cam. Such sources may
represent a different evolutionary state of X-ray binaries previously
undetected with the lower energy space telescopes ; if it is so, a new class of
strongly absorbed X-ray binaries is being unveiled by INTEGRAL.


title:
Minihalo photoevaporation during cosmic reionization: evaporation times
  and photon consumption rates

abstract:
  The weak, R-type ionization fronts (I-fronts) which swept across the
intergalactic medium (IGM) during the reionization of the universe often found
their paths blocked by cosmological minihaloes. When this happened, the neutral
gas which filled each minihalo was photoevaporated; as the I-front burned its
way through the halo, decelerating from R-type to D-type, all the gas was blown
back into the IGM as an ionized, supersonic wind. In a previous paper (Shapiro,
Iliev and Raga 2004), we described this process and presented our results of
the first simulations of it by numerical gas dynamics with radiation transport
in detail. For illustration we focused on the particular case of a 10^7 solar
masses minihalo overrun at z=9 by an intergalactic I-front caused by a distant
source of ionizing radiation, for different source spectra (either stellar from
massive Pop. II or III stars, or QSO-like) and a flux level typical of that
expected during reionization. In a LambdaCDM universe, minihaloes formed in
abundance before and during reionization and, thus, their photoevaporation is
an important, possibly dominant, feature of reionization, which slowed it down
and wasted ionizing photons. We have now performed a larger set of
high-resolution simulations to determine and quantify the dependence of
minihalo photoevaporation times and photon consumption rates on halo mass,
redshift, ionizing flux level and spectrum. We find that the average number of
ionizing photons each minihalo atom absorbs during its photoevaporation is
typically in the range 2-10. For the collapsed fraction in minihaloes expected
during reionization, this can add about 1 photon per total atom to the
requirements for completing reionization, potentially doubling the minimum
number of photons required to reionize the universe.


title: Ultraviolet Extinction Properties in the Milky Way

abstract:
  We have assembled a homogeneous database of 417 ultraviolet (UV) extinction
curves for reddened sightlines having International Ultraviolet Explorer (IUE)
spectra. We have combined these with optical and 2MASS photometry allowing
estimates of the ratio of total-to-selective extinction, R(V), for the entire
sample. Fitzpatrick-Massa (FM) parameters have also been found for the entire
sample. This is the largest study of parameterized UV extinction curves yet
published and it covers a wide range of environments, from dense molecular
clouds to the diffuse interstellar medium (ISM), with extinctions A(V) ranging
from 0.50 to 4.80. It is the first to extend far beyond the solar neighborhood
and into the Galaxy at large, with 30 sightlines having distances > 5 kpc.
Previously, the longest sightlines with FM parameters and R(V) extended ~ 1
kpc. We find that (1.) the CCM extinction law applies for 93% of the
sightlines, implying that dust processing in the Galaxy is efficient and
systematic; (2.) the central wavelength of the 2175 A bump is constant; (3.)
the 2175 A bump width is dependent on environment. Only four sightlines show
systematic deviations from CCM, HD 29647, 62542, 204827, and 210121. These
sightlines all sample dense, molecule-rich clouds. The new extinction curves
and values of R(V) allow us to revise the CCM law.


title: The Nature of Lya Blobs: Supernova-Dominated Primordial Galaxies

abstract:
  We consider a forming galaxy undergoing multitudinous supernova (SN)
explosions, as a possible model of \lya blobs (LABs). For this purpose, an
ultra--high resolution hydrodynamic simulation is performed using $1024^3$ grid
points, where SN remnants are resolved with sufficient accuracy. It is found
that multiple SN explosions produce kpc--size expanding hot bubbles, which
drive cool, dense shells by strong shock. The colliding high--density cooling
shells radiate intensive \lya emission, resulting in a high \lya luminosity of
$\sim10^{43}$ erg s$^{-1}$, comparable to the observed level in LABs. Also,
recently discovered bubbly features in some LABs are quite similar to the
structure predicted in the present simulation. Furthermore, the result
demonstrates that LABs are representative of evolving primordial galaxies; they
could hold direct information on the early chemical enrichment of galaxies,
contrary to present--day galaxies which have undergone intense recycling of
interstellar matter, thus erasing most of the early chemical history. It turns
out that the metal mixing proceeds in a very inhomogeneous fashion, so that
there appears a large spread of metallicity, that is,$[{\rm Fe/H}] \approx 0
{\rm ~to} -5$ or $[{\rm O/H}] \approx 1 {\rm ~to} -4$. Hence, the early
galactic chemical evolution may have proceeded in a different manner from that
hitherto considered in one--zone models.


title: Quiescent Dense Gas in Protostellar Clusters: the Ophiuchus A Core

abstract:
  We present combined BIMA interferometer and IRAM 30 m Telescope data of N2H+
1-0 line emission across the nearby dense, star forming core Ophiuchus A (Oph
A) at high linear resolution (e.g., ~1000 AU). Six maxima of integrated line
intensity are detected which we designate Oph A-N1 through N6. The N4 and N5
maxima are coincident with the starless continuum objects SM1 and SM2
respectively but the other maxima are not coincident with previously-identified
objects. In contrast, relatively little N2H+ 1-0 emission is coincident with
the starless object SM2 and the Class 0 protostar VLA 1623. The FWHM of the
N2H+ 1-0 line, Delta V, varies by a factor of ~5 across Oph A. Values of Delta
V < 0.3 km/s are found in 14 locations in Oph A, but only that associated with
N6 is both well-defined spatially and larger than the beam size. Centroid
velocities of the line, V_LSR, vary relatively little, having an rms of only
\~0.17 km/s. Small-scale V_LSR gradients of <0.5 km/s over ~0.01 pc are found
near SM1, SM1N, and SM2, but not N6. The low N2H+ abundances of SM2 or VLA 1623
relative to SM1, SM1N, or N6 may reflect relatively greater amounts of N2
adsorption onto dust grains in their colder and probably denser interiors. The
low Delta V of N6, i.e., 0.193 km/s FWHM, is only marginally larger than the
FWHM expected from thermal motions alone, suggesting turbulent motions in the
Oph A core have been reduced dramatically at this location. The non-detection
of N6 in previous thermal continuum maps suggests that interesting sites
possibly related to star formation may be overlooked in such data.


title: Transient phenomena

abstract:
  The SKA's design is driven by the needs of cutting-edge radio astronomy for
sensitivity and spacial resolution. However its design is also driven by the
desire to explore the transient radio Universe. In addition to pulsars, the SKA
will be able to carry out high time resolution observations of several classes
of known and predicted transient sources. Here we consider a selection of them,
and describe how observational demands affect the instrument's design.


title: Towards a More Standardized Candle Using GRB Energetics and Spectra

abstract:
  The use of GRB energetics for cosmography has long been advanced as a means
to probe out to high redshifts, to the epoch of deceleration. However, the
prompt energy release in GRBs, even when corrected for jetting geometry, is far
from being a standard candle. We explore the cosmographic potential of a GRB
standard candle based on the newly-discovered relation by Ghirlanda et al.
between the apparent geometry-corrected energies (E_gamma) and the peak of the
prompt burst spectrum (E_p). We present an explicit, self-consistent formalism
for correcting GRB energies with a thorough accounting for observational
uncertainties. In contrast to other work, we demonstrate that the current
sample of 19 GRBs is not yet cosmographically competitive with results from
other studies (e.g., SNe Ia). Although the E_p-E_gamma relation is a
significant correlation across a range of cosmologies, the goodness of fit of
the data to a power law, depends strongly on input assumptions -- especially
the unknown density of the circumburst medium. Independent of assumptions, with
very few low-z bursts, the current sample is most sensitive to Omega_M but
essentially insensitive to Omega_Lambda. The proper use of the relation clearly
brings GRBs an impressive step closer toward a standardizable candle, but until
the physical origin of the E_p-E_gamma relation is understood, calibrated with
a training set of low redshift bursts, and the major potential systematic
uncertainties and selection effects are addressed, we urge caution concerning
claims of the utility of GRBs for cosmography (abridged).


title: Detectability of GRB Iron Lines by Swift, Chandra and XMM

abstract:
  The rapid acquisition of positions by the upcoming Swift satellite will allow
the monitoring for X-ray lines in GRB afterglows at much earlier epochs than
was previously feasible. We calculate the possible significance levels of iron
line detections as a function of source redshift and observing time after the
trigger, for the Swift XRT, Chandra ACIS and XMM Epic detectors. For bursts
with standard luminosities, decay rates and equivalent widths of 1 keV assumed
constant starting at early source-frame epochs, Swift may be able to detect
lines up to z~1.5 with a significance of better than 3 sigma for times up to
10^4 s. The same lines would be detectable with better than 4 sigma
significance at z up to 6 by Chandra, and up to 8 by XMM, for times of up to
10^5 s. For similar bursts with a variable equivalent width peaking at 1 keV
between 0.5 and 1 days in the source frame, Swift achieves the same
significance level for z~1 at t~1 day, while Chandra reaches the previous
detection significances around t~ 1-2 days for z~ 2-4, i.e. the line is
detectable near the peak equivalent width times, and undetectable at earlier or
later times. For afterglows in the upper range of initial X-ray luminosites
afterglows, which may also be typical of pop. III bursts, similar significance
levels are obtained out to substantially higher redshifts. A distinction
between broad and narrow lines to better than 3 sigma is possible with Chandra
and XMM out to z~2 and ~6.5, respectively, while Swift can do so up to z~1, for
standard burst parameters. A distinction between different energy centroid
lines of 6.4 keV vs. 6.7 KeV (or 6.7 keV vs. Cobalt 7.2 keV) is possible up to
z~0.6, 1.2, and 2 (z~ 1, 5, 7.5), with Swift,Chandra, and XMM respectively.


title: Detecting Dark Energy in Orbit -- the Cosmological Chameleon

abstract:
  We show that the chameleon scalar field can drive the current phase of cosmic
acceleration for a large class of scalar potentials that are also consistent
with local tests of gravity. These provide explicit realizations of a
quintessence model where the quintessence scalar field couples directly to
baryons and dark matter with gravitational strength. We analyze the
cosmological evolution of the chameleon field and show the existence of an
attractor solution with the chameleon following the minimum of its effective
potential. For a wide range of initial conditions, spanning many orders of
magnitude in initial chameleon energy density, the attractor is reached before
nucleosynthesis. Surprisingly, the range of allowed initial conditions leading
to a successful cosmology is wider than in normal quintessence. We discuss
applications to the cyclic model of the universe and show how the chameleon
mechanism weakens some of the constraints on cyclic potentials.


title: Low angular momentum accretion-outflow model of flares from Sgr A$^*$

abstract:
  We employ a low angular momentum accretion-outflow scenario to model the
flares emanating out from the central region of Sgr A$^*$. The primary donor
for matter accreting onto the central SMBH of Sgr A$^*$ is assumed to be the WR
star ISR 13 E3. We analytically calculate the specific energy and angular
momentum density of stellar wind originating from ISR 13 E3 and study the
dynamics of that wind down to the very close vicinity of the central SMBH of
Sgr A$^*$. We show that on the way to the Galactic centre, such wind-fed
accretion may encounter standing shocks and such shock drives outflow from the
close vicinity of the SMBH. Matter content of such outflow is computed and it
is argued that such outflow is responsible for production of the Galactic
centre flares. We then self-consistently compute the luminosity ${\cal L}_j$
and the duration time scale $\tau$ of such flares, as a function of fundamental
accretion parameters. Our theoretical calculation of ${\cal L}_j$ and $\tau$
are in good agreement with observational results.


title:
Chandra Observations of Diffuse Gas and Luminous X-ray Sources Around
  the X-ray Bright Elliptical NGC 1600

abstract:
  (Abridged) We observed the X-ray bright E3 galaxy NGC 1600 and nearby group
members with the Chandra X-ray Observatory ACIS S3. Unresolved emission
dominates the observation; however, we resolved some emission into 71 sources,
most of which are low-mass X-ray binaries (LMXBs) associated with NGC 1600.
Twenty-one sources have L_X>2E39 ergs/s (0.3-10.0 keV; assuming they are at the
distance of NGC 1600) marking them as ultraluminous X-ray point source (ULX)
candidates; we expect only 11+/-2 are unrelated sources. NGC 1600 may have the
largest number of ULX candidates in an early-type galaxy to date; however,
cosmic variance in the number of background AGN cannot be ruled out. There are
indications that there are also a large number of unresolved point sources. We
propose that these are associated with globular clusters (GCs), and that NGC
1600 has a large GC specific frequency. The unresolved emission appears to have
two gas components. We interpret the soft inner component (a<~25", kT~0.85 keV)
as the interstellar medium of NGC 1600 and the hotter outer component (a>~25",
kT~1.5 keV) as the intragroup medium of the NGC 1600 group. The X-ray image
shows several interesting structures, excess emission roughly cospatial with
H$\alpha$ and dust filaments, possible holes in the X-ray emission roughly
coincident with radio lobes, excess emission to the northeast possibly
indicating the center of the group potential, and a tail of X-ray emission from
the group galaxy NGC 1603 probably due to ram-pressure stripping


title: Non-parametric inversion of strong lensing systems

abstract:
  We revisit the issue of non-parametric gravitational lens reconstruction and
present a new method to obtain the cluster mass distribution using strong
lensing data without using any prior information on the underlying mass. The
method relies on the decomposition of the lens plane into individual cells. We
show how the problem in this approximation can be expressed as a system of
linear equations for which a solution can be found. Moreover, we propose to
include information about the null space. That is, make use of the pixels where
we know there are no arcs above the sky noise. The only prior information is an
estimation of the physical size of the sources. No priors on the luminosity of
the cluster or shape of the halos are needed thus making the results very
robust. In order to test the accuracy and bias of the method we make use of
simulated strong lensing data. We find that the method reproduces accurately
both the lens mass and source positions and provide error estimates.


title:
Evolutionary synthesis of galaxies at high spectral resolution with the
  code PEGASE-HR

abstract:
  We present PEGASE-HR, a new stellar population synthesis program generating
high resolution spectra (R=10 000) over the optical range lambda=400--680 nm.
It links the spectro-photometric model of galaxy evolution PEGASE.2 (Fioc &
Rocca-Volmerange 1997) to an updated version of the ELODIE library of stellar
spectra observed with the 193 cm telescope at the Observatoire de
Haute-Provence (Prugniel & Soubiran 2001a). The ELODIE star set gives a fairly
complete coverage of the Hertzprung-Russell (HR) diagram and makes it possible
to synthesize populations in the range [Fe/H]=-2 to +0.4. This code is an
exceptional tool for exploring signatures of metallicity, age, and kinematics.
We focus on a detailed study of the sensitivity to age and metallicity of the
high-resolution stellar absorption lines and of the classical metallic indices
proposed until now to solve the age-metallicity degeneracy. Validity tests on
several stellar lines are performed by comparing our predictions for Lick
indices to the models of other groups. The comparison with the lower resolution
library BaSeL (Lejeune et al. 1997) confirms the quality of the ELODIE library
when used for simple stellar populations (SSPs) from 10 Myr to 20 Gyr.
Predictions for the evolved populations of globular clusters and elliptical
galaxies are given and compared to observational data. Two new high-resolution
indices are proposed around the Hgamma line. They should prove useful in the
analysis of spectra from the new generation of telescopes and spectrographs.


title: Anomalously low PAH emission from low-luminosity galaxies

abstract:
  The Spitzer Space Telescope First Look Survey Infrared Array Camera (IRAC)
near and mid-infrared imaging data partially overlaps the Sloan Digital Sky
Survey (SDSS), with 313 visually selected (r<17.6 mag) SDSS Main Sample
galaxies in the overlap region. The 3.5 and 7.8 um properties of the galaxies
are investigated in the context of their visual properties, where the IRAC
[3.5] magnitude primarily measures starlight, and the [7.8] magnitude primarily
measures PAH emission from the interstellar medium. As expected, we find a
strong inverse correlation between [3.5]-[7.8] and visual color; galaxies red
in visual colors (`red galaxies') tend to show very little dust and molecular
emission (low `PAH-to-star' ratios), and galaxies blue in visual colors (`blue
galaxies,' ie, star-forming galaxies) tend to show large PAH-to-star ratios.
Red galaxies with high PAH-to-star ratios tend to be edge-on disks reddened by
dust lanes. Simple, visually inferred attenuation corrections bring the visual
colors of these galaxies in line with those of face-on disks; ie, PAH emission
is closely related to attenuation-corrected, optically inferred star-formation
rates. Blue galaxies with anomalously low PAH-to-star ratios are all
low-luminosity star-forming galaxies. There is some weak evidence in this
sample that the deficiency in PAH emission for these low-luminosity galaxies
may be related to emission-line metallicity.


title: TrES-1: The Transiting Planet of a Bright K0V Star

abstract:
  We report the detection of a transiting Jupiter-sized planet orbiting a
relatively bright (V=11.79) K0V star. We detected the transit light-curve
signature in the course of the TrES multi-site transiting planet survey, and
confirmed the planetary nature of the companion via multicolor photometry and
precise radial velocity measurements. We designate the planet TrES-1; its
inferred mass is 0.75 +/- 0.07 Jupiter masses, its radius is 1.08 (+0.18/-0.04)
Jupiter radii, and its orbital period is 3.030065 +/- 0.000008 days. This
planet has an orbital period similar to that of HD 209458b, but about twice as
long as those of the OGLE transiting planets. Its mass is indistinguishable
from that of HD 209458b, but its radius is significantly smaller and fits the
theoretical models without the need for an additional source of heat deep in
the atmosphere, as has been invoked by some investigators for HD 209458b.


title:
Comparison of Nuclear Starburst Luminosities between Seyfert 1 and 2
  Galaxies Based on Near-infrared Spectroscopy

abstract:
  We report on infrared K- (2-2.5 micron) and L-band (2.8-4.1 micron) slit
spectroscopy of 23 Seyfert 1 galaxies in the CfA and 12 micron samples. A
polycyclic aromatic hydrocarbon (PAH) emission feature at 3.3 micron in the L
band is primarily used to investigate nuclear star-forming activity in these
galaxies. The 3.3 micron PAH emission is detected in 10 sources (=43%),
demonstrating that detection of nuclear star-formation in a significant
fraction of Seyfert 1 galaxies is now feasible. For the PAH-detected nuclei,
the surface brightness values of the PAH emission are as high as those of
typical starbursts, suggesting that the PAH emission probes the putative
nuclear starbursts in the dusty tori around the central active galactic nuclei
(AGNs). The magnitudes of the nuclear starbursts are quantitatively estimated
from the observed 3.3 micron PAH emission luminosities. The estimated starburst
luminosities relative to some indicators of AGN powers in these Seyfert 1s are
compared with 32 Seyfert 2s in the same samples that we have previously
observed. We find that there is no significant difference in nuclear starburst
to AGN luminosity ratios between Seyfert 1 and 2 galaxies, and that nuclear
starburst luminosity positively correlates with AGN power in both types of
Seyferts. Our results favor a slightly-modified AGN unification model, which
predicts that nuclear starbursts occurring in the dusty tori of Seyferts are
physically connected to the central AGNs, rather than the classical unification
paradigm, in which the dusty tori simply hide the central AGNs of Seyfert 2s
and reprocess AGN radiation as infrared dust emission in Seyferts. No
significant differences in nuclear star formation properties are recognizable
between Seyfert 1s in the CfA and 12 micron samples.


title:
Breit-Pauli energy levels, transition probabilities, and lifetimes for
  3d^5 levels in Fe IV of astrophysical interest

abstract:
  Energy levels, lifetimes, and transition probabilities for transitions
between computed levels of 3d^5 of Fe IV are reported. The E2 and M1 transition
probabilities are compared with earlier theoretical results, often only the
values published by Garstang in 1958. From the available astronomical
observations of optical emission lines arising from the same level, a few
direct tests are now possible and they show consistency with the theoretical
calculations.


title: The Photometric Properties of Isolated Early-Type Galaxies

abstract:
  Isolated galaxies are important since they probe the lowest density regimes
inhabited by galaxies. We define a sample of 36 nearby isolated early-type
galaxies for further study. Our isolation criteria require them to have no
comparable-mass neighbours within 2 B-band magnitudes, 0.67 Mpc in the plane of
the sky and 700 km/s in recession velocity. New wide-field optical imaging of
10 isolated galaxies with the Anglo-Australian Telescope confirms their
early-type morphology and relative isolation. We also present imaging of 4
galaxy groups as a control sample. The isolated galaxies are shown to be more
gravitationally isolated than the group galaxies. We find that the isolated
early-type galaxies have a mean effective colour of (B-R)_e = 1.54 +/- 0.14,
similar to their high-density counterparts. They reveal a similar
colour-magnitude relation slope and small intrinsic scatter to cluster
ellipticals. They also follow the Kormendy relation of surface brightness
versus size for luminous cluster galaxies. Such properties suggest that the
isolated galaxies formed at a similar epoch to cluster galaxies, such that the
bulk of their stars are very old. However, our galaxy modelling reveals
evidence for dust lanes, plumes, shells, boxy and disk isophotes in four out of
nine galaxies. Thus at least some isolated galaxies have experienced a recent
merger/accretion event which may have induced a small burst of star formation.
We derive luminosity functions for the isolated galaxies and find a faint slope
of -1.2, which is similar to the `universal' slope found in a wide variety of
environments. We examine the number density distribution of galaxies in the
field of the isolated galaxies.


title:
The survival and destruction of X-ray coronae of early-type galaxies in
  the rich cluster environments: a case study of Abell 1367

abstract:
  A new Chandra observation of the northwest region of the galaxy cluster A1367
reveals four cool galaxy coronae (0.4 - 1.0 keV) embedded in the hot
intracluster medium (ICM) (5 - 6 keV). While the large coronae of NGC 3842 and
NGC 3837 appear symmetric and relaxed, the galaxy coronae of the $\lsim$ L*
galaxies (NGC 3841 and CGCG 97090) are disturbed and being stripped. Massive
galaxies, with dense cooling cores, are better able to resist ram pressure
stripping and survive in rich environments than $\lsim$ L* galaxies whose
galactic coronae are much less dense. The survival of these cool coronae
implies that thermal conduction from the hot surrounding ICM has to be
suppressed by a factor of at least 60, at the corona boundary. Within the
galaxy coronae of NGC 3842 and NGC 3837, stellar mass loss or heat conduction
with the Spitzer value may be sufficient to balance radiative cooling. Energy
deposition at the ends of collimated jets may heat the outer coronae, but allow
the survival of a small, dense gas core (e.g., NGC 3842 in A1367 and NGC 4874
in Coma). The survived X-ray coronae become significantly smaller and fainter
with the increasing ambient pressure.


title:
Big-Bang Nucleosynthesis and Hadronic Decay of Long-Lived Massive
  Particles

abstract:
  We study the big-bang nucleosynthesis (BBN) with the long-lived exotic
particle, called X. If the lifetime of X is longer than \sim 0.1 sec, its decay
may cause non-thermal nuclear reactions during or after the BBN, altering the
predictions of the standard BBN scenario. We pay particular attention to its
hadronic decay modes and calculate the primordial abundances of the light
elements. Using the result, we derive constraints on the primordial abundance
of X. Compared to the previous studies, we have improved the following points
in our analysis: The JETSET 7.4 Monte Carlo event generator is used to
calculate the spectrum of hadrons produced by the decay of X; The evolution of
the hadronic shower is studied taking account of the details of the energy-loss
processes of the nuclei in the thermal bath; We have used the most recent
observational constraints on the primordial abundances of the light elements;
In order to estimate the uncertainties, we have performed the Monte Carlo
simulation which includes the experimental errors of the cross sections and
transfered energies. We will see that the non-thermal productions of D, He3,
He4 and Li6 provide stringent upper bounds on the primordial abundance of
late-decaying particle, in particular when the hadronic branching ratio of X is
sizable. We apply our results to the gravitino problem, and obtain upper bound
on the reheating temperature after inflation.


title: Magnetorotational instability in protoplanetary discs

abstract:
  We investigate the linear growth and vertical structure of the
magnetorotational instability (MRI) in weakly ionised, stratified accretion
discs. The magnetic field is initially vertical and dust grains are assumed to
have settled towards the midplane, so charges are carried by electrons and ions
only. Solutions are obtained at representative radial locations from the
central protostar for different choices of the initial magnetic field strength,
sources of ionisation, and disc surface density.
  The MRI is active over a wide range of magnetic field strengths and fluid
conditions in low conductivity discs. For the minimum-mass solar nebula model,
incorporating cosmic ray ionisation, perturbations grow at 1 AU for B < 8 G.
For a significant subset of these strengths (0.2 - 5 G), the growth rate is of
order the ideal MHD rate (0.75 Omega). Similarly, when cosmic rays are assumed
to be excluded from the disc by the winds emitted by the magnetically active
protostar, unstable modes grow at this radius for B less than about 2 G.
  This study shows that, despite the low magnetic coupling, the magnetic field
is dynamically important for a large range of fluid conditions and field
strengths in protostellar discs. Hall diffusion largely determines the
structure and growth rate of these perturbations for all studied radii. At
radii of order 1 AU, in particular, it is crucial to incorporate the full
conductivity tensor in studies of the dynamics of astrophysical discs.
(Abridged)


title:
An Analysis of the Large Scale N-body Simulation using the Minkowski
  Functionals

abstract:
  We analyze the Minkowski functionals with a large $N$-body simulation of a
standard $\Lambda$CDM model, focusing on transition scales between linear and
non-linear gravitational evolution. We numerically calculate the Minkowski
functionals with sufficient accuracies to investigate the transition scales,
10--$50\himpc$. The results are compared with analytic formulae of linear and
second-order perturbation theories. We first show that the skewness parameters
of the density fluctuations, which are important in second-order analytic
formulae of the Minkowski functionals, are in good agreement with the
perturbation theory. Considering relative differences between the Minkowski
functionals of the analytic formulae and that of the simulation data, we
evaluate accuracy levels of the predictions of the perturbation theory. When
the straightforward threshold $\nu$ by density value is used in Minkowski
functionals, the accuracy of the second-order perturbation theory is within 10%
for smoothing length $R > 15\himpc$, and within a several % for $R > 20\himpc$.
The accuracies of the linear theory are 2--5 times worse than that. When the
rescaled threshold by volume fraction, $\nu_{\rm f}$ is used, accuracies of
both linear and second-order theories are within a few % on all scales of
$10\himpc < R < 50\himpc$.


title:
Gravitational collapse in an expanding background and the role of
  substructure I: Planar collapse

abstract:
  We study the interplay of clumping at small scales with the collapse and
relaxation of perturbations at much larger scales. We present results of our
analysis when the large scale perturbation is modelled as a plane wave. We find
that in absence of substructure, collapse leads to formation of a pancake with
multi-stream regions. Dynamical relaxation of plane wave is faster in presence
of substructure. Scattering of substructures and the resulting enhancement of
transverse motions of haloes in the multi-stream region lead to a thinner
pancake. In turn, collapse of the plane wave leads to formation of more massive
collapsed haloes as compared to the collapse of substructure in absence of the
plane wave. The formation of more massive haloes happens without any increase
in the total mass in collapsed haloes. A comparison with the Burgers' equation
approach in absence of any substructure suggests that the preferred value of
effective viscosity depends primarily on the number of streams in a region.


title:
A purely geometric distance to the binary star Atlas, a member of the
  Pleiades

abstract:
  We present radial velocity and new interferometric measurements of the double
star Atlas, which permit, with the addition of published interferometric data,
to precisely derive the orbital parameters of the binary system and the masses
of the components. The derived semi-major axis, compared with its measured
angular size, allows to determine a distance to Atlas of 132+-4 pc in a purely
geometrical way. Under the assumption that the location of Atlas is
representative of the average distance of the cluster, we confirm the distance
value generally obtained through main sequence fitting, in contradiction with
the early Hipparcos result (118.3+-3.5 pc).


title: Formation of Omega Centauri by Tidal Stripping of a Dwarf Galaxy

abstract:
  We have investigated whether or not a tidal stripping scenario can reproduce
the observed surface-brightness profile of omega Centauri using N-body
simulations. Assuming that the progenitor of omega Centauri is a dwarf
elliptical galaxy, we model it with a King model with a core radius being the
same as that of omega Centauri. A dark matter halo of the dwarf is not taken
into account. We consider two different models of the Milky Way potential: a
singular isothermal sphere and a three-component model. The progenitor dwarf is
expressed as an N-body system, which orbits in the fixed Galactic potential.
The dwarf lost more than 90 per cent of its mass during the first few
pericenter passages. Thereafter, the mass remains practically constant. The
final surface-density profile is in good agreement with the observational data
on omega Centauri, if the pericenter distance of the orbit of the progenitor
dwarf is around 500 pc. This value is within the error bar of the current
proper motion data on omega Centauri and Galactic parameters. Although our
simulation is limited to a King-like progenitor dwarf without a dark matter
halo, it strongly suggests that the current density profile of omega Centauri
is nicely reproduced by a tidal stripping scenario, in other words, that omega
Centauri can plausibly be identified with a stripped dwarf elliptical.


title: The 2004--2006 outburst and environment of V1647 Ori

abstract:
  (Abridged) We studied the brightness and spectral evolution of the young
eruptive star V1647 Ori during its recent outburst in the period 2004 February
- 2006 Sep. We performed a photometric follow-up in the bands V, R_C, I_C, J,
H, K_s as well as visible and near-IR spectroscopy. The main results are as
follows: The brightness of V1647 Ori stayed more than 4 mag above the
pre-outburst level until 2005 October when it started a rapid fading. In the
high state we found a periodic component in the optical light curves with a
period of 56 days. The delay between variations of the star and variations in
the brightness of clump of nearby nebulosity corresponds to an angle of 61+/-14
degrees between the axis of the nebula and the line of sight. A steady decrease
of HI emission line fluxes could be observed. In 2006 May, in the quiescent
phase, the HeI 1.083 line was observed in emission, contrary to its deep
blueshifted absorption observed during the outburst. The J-H and H-K_s color
maps of the infrared nebula reveal an envelope around the star. The color
distribution of the infrared nebula suggests reddening of the scattered light
inside a thick circumstellar disk. We show that the observed properties of
V1647 Ori could be interpreted in the framework of the thermal instability
models of Bell et al. (1995). V1647 Ori might belong to a new class of young
eruptive stars, defined by relatively short timescales, recurrent outbursts,
modest increase in bolometric luminosity and accretion rate, and an
evolutionary state earlier than that of typical EXors.


title: On the Origin of the Wide HI Absorption Line Toward Sgr A*

abstract:
  We have imaged a region of about 5' extent surrounding Sgr A* in the HI 21
cm-line absorption using the Very Large Array. A Gaussian decomposition of the
optical depth spectra at positions within about 2' (approx. 5 pc at 8.5 kpc) of
Sgr A* detects a wide line underlying the many narrow absorption lines. The
wide line has a mean peak optical depth of 0.32 +/- 0.12 centered at a mean
velocity of V(lsr) = -4 +/- 15 km/s. The mean full width at half maximum is 119
+/- 42 km/s. Such a wide line is absent in the spectra at positions beyond
about 2' from Sgr A*. The position-velocity diagrams in optical depth reveal
that the wide line originates in various components of the circumnuclear disk
(radius approx. 1.3') surrounding Sgr A*. These components contribute to the
optical depth of the wide line in different velocity ranges. The
position-velocity diagrams do not reveal any diffuse feature which could be
attributed to a large number of HI clouds along the line of sight to Sgr A*.
Consequently, the wide line has no implications either to a global population
of shocked HI clouds in the Galaxy or to the energetics of the interstellar
medium as was earlier thought.


title: Structure and star formation in disk galaxies II. Optical imaging

abstract:
  We present optical observations of a sample of 57 spiral galaxies and
describe the procedures followed to reduce the data. We have obtained images in
the optical B and I broad bands, as well as in H alpha, with moderate spatial
resolution and across wide enough fields to image the complete disks of the
galaxies. In addition, we observed 55 of our sample galaxies in the R and eight
in the V band, and imaged a subset through a dedicated narrow continuum filter
for the H alpha line. We describe the data reduction procedures we developed in
the course of this work to register, combine and photometrically calibrate each
set of images for an individual galaxy. We describe in some detail the
procedure used to subtract the continuum emission from our H alpha images. In
companion papers, we describe near-infrared imaging of the galaxy sample, and
present analyses of disk scale lengths, and of properties of bars, rings, and
HII regions in the sample galaxies. The images described here will be made
available for use by other researchers through the CDS.


title: Nuclear properties of a sample of nearby spirals from STIS imaging

abstract:
  We present surface photometry for the central regions of a sample of 48
spiral galaxies (mostly unbarred and barred of types Sbc or Sc) observed with
the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope.
Surface brightness profiles were derived and modeled with a Nuker law. We also
analyzed archival Wide Field Planetary Camera~2 images with a larger field of
view, available for 18 galaxies in our sample. We modeled the extracted bulge
surface brightness profiles with an exponential, a de Vaucouleurs or a Sersic
profile. In agreement with previous studies, we find that bulges of Sbc
galaxies fall into two categories: bulges well described by an exponential
profile and those well described by an de Vaucouleurs profile. Only one galaxy
requires the use of a more general Sersic profile to properly describe the
bulge. Nuclear photometrically distinct components are found in ~55% of the
galaxies. For those that we classify as star clusters based on their resolved
extent we find absolute magnitudes that are brighter on average than those
previously identified in spiral galaxies. This might be due to a bias in our
sample toward star forming galaxies, combined with a trend for star forming
galaxies to host brighter central clusters.


title:
The prompt X-ray emission of GRB011211: possible evidence of a transient
  absorption feature

abstract:
  We report on observation results of the prompt X- and gamma-ray emission from
GRB011211. This event was detected with the Gamma-Ray Burst Monitor and one of
the Wide Field Cameras aboard the BeppoSAX satellite. The optical counterpart
to the GRB was soon identified and its redshift determined (z = 2.140), while
with the XMM-Newton satellite, the X-ray afterglow emission was detected.
Evidence of soft X-ray emission lines was reported by Reeves et al. (2002), but
not confirmed by other authors. In investigating the spectral evolution of the
prompt emission we find the possible evidence of a transient absorption feature
at 6.9^{+0.6}_{-0.5} keV during the rise of the primary event. The significance
of the feature is derived with non parametric tests and numerical simulations,
finding a chance probability which ranges from 3x10^{-3} down to 4x10^{-4}. The
feature shows a Gaussian profile and an equivalent width of 1.2^{+0.5}_{-0.6}
keV. We discuss our results and their possible interpretation.


title: On the dust tori in Palomar-Green quasars

abstract:
  The dust clouds in the torus of the quasar are irradiated by the central
source, and the clouds at the inner radius of the torus re-radiate mostly in
the near-infrared (NIR) wavebands. The ratio of the near-infrared luminosity to
the bolometric luminosity L_NIR/L_bol can therefore reflect the torus geometry
to some extent. We find a significant correlation between the ratio of the
near-infrared luminosity to the bolometric luminosity L_NIR/L_bol and the
central black hole mass M_bh for the Palomar-Green(PG) quasars, whereas no
correlation is found between the Eddington ratio L_bol/L_Edd and the ratio
L_NIR/L_bol. Similar correlations are found for the mid-infrared and
far-infrared cases. It may imply that the torus geometry, i.e., the solid angle
subtended by the dust torus as seen from the central source, does not evolve
with the accretion rate. The correlation of the solid angle subtended by the
torus with the central black hole mass M_bh implies that the formation of the
dust torus is likely regulated by the central black hole mass. We find that the
torus thickness H increases with quasar bolometric luminosities, which is
different from the constant torus thickness H with luminosity assumed in the
receding torus model. The mean covering factor of the dust clouds at the inner
radius of the torus derived from the IR emission data is ~0.39 for PG quasars.
The average relative thickness H/R of the tori in the PG quasars derived from
the ratios of the infrared to bolometric luminosities is ~0.9. We suggest that
the further IR observations on a larger quasar sample including more fainter
quasars by the Spitzer Space Telescope will help understand the physics of the
dust tori in quasars.


title: Ejection of Supernova-Enriched Gas From Dwarf Disk Galaxies

abstract:
  We examine the efficiency with which supernova-enriched gas may be ejected
from dwarf disk galaxies, using a methodology previously employed to study the
self-enrichment efficiency of dwarf spheroidal systems. Unlike previous studies
that focused on highly concentrated starbursts, in the current work we consider
discrete supernova events spread throughout various fractions of the disk. We
model disk systems having gas masses of 10^8 and 10^9 solar masses with
supernova rates of 30, 300, and 3000 per Myr. The supernova events are confined
to the midplane of the disk, but distributed over radii of 0, 30, and 80% of
the disk radius, consistent with expectations for Type II supernovae. In
agreement with earlier studies, we find that the enriched material from
supernovae is largely lost when the supernovae are concentrated near the
nucleus, as expected for a starburst event. In contrast, however, we find the
loss of enriched material to be much less efficient when the supernovae occur
over even a relatively small fraction of the disk. The difference is due to the
ability of the system to relax following supernova events that occur over more
extended regions. Larger physical separations also reduce the likelihood of
supernovae going off within low-density "chimneys" swept out by previous
supernovae. We also find that, for the most distributed systems, significant
metal loss is more likely to be accompanied by significant mass loss. A
comparison with theoretical predications indicates that, when undergoing
self-regulated star formation, galaxies in the mass range considered shall
efficiently retain the products of Type II supernovae.


title: Supernova Asymmetries and Pulsar Kicks -- Views on Controversial Issues

abstract:
  Two- and three-dimensional simulations demonstrate that hydrodynamic
instabilities can lead to low-mode (l=1,2) asymmetries of the fluid flow in the
neutrino-heated layer behind the supernova shock. This provides a natural
explanation for aspherical mass ejection and for pulsar recoil velocities even
in excess of 1000 km/s. We propose that the bimodality of the pulsar velocity
distribution might be a consequence of a dominant l=1 mode in case of the fast
component, while higher-mode anisotropy characterizes the postshock flow and SN
ejecta during the birth of the slow neutron stars. We argue that the observed
large asymmetries of supernovae and the measured high velocities of young
pulsars therefore do not imply rapid rotation of the iron core of the
progenitor star, nor do they require strong magnetic fields to play a crucial
role in the explosion. Anisotropic neutrino emission from accretion contributes
to the neutron star acceleration on a minor level, and pulsar kicks do not make
a good case for non-standard neutrino physics in the nascent neutron star.


title: Large-scale Structure with the SKA

abstract:
  A standard theoretical paradigm for the formation of large-scale structure in
the distribution of galaxies has now been established, based on the
gravitational instability of cold dark matter in a background cosmology
dominated by vacuum energy. Significant uncertainties remain in the modelling
of complex astrophysical processes involved in galaxy formation, perhaps most
fundamentally in the relationship between the distributions of luminous
galaxies and the underlying dark matter. I argue that the Square Kilometre
Array is likely to provide information crucial to understanding this
relationship and how it evolves with time.


title: Gravitational instability and clustering in a disk of planetesimals

abstract:
  For a long time, gravitational instability in the disk of planetesimals has
been suspected to be the main engine responsible for the beginning of dust
growth, its advantage being that it provides for rapid growth. Its real
importance in planetary formation is still debated, mainly because the
potential presence of turbulence can prevent the settling of particles into a
gravitationally unstable layer. However, several mechanisms could yield
strongly inhomogeneous distributions of solids in the disk: radial drift,
trapping in vortices, perturbations by other massive bodies, etc. In this paper
we present a numerical study of a gravitationally unstable layer. This allows
us to go beyond the classical analytical study of linear perturbations,
exploring a highly non-linear regime. A hierarchical growth of structure in the
presence of dissipation (gas drag) can yield large, virialized clusters of
planetesimals, the first time such clusters have been observed in the context
of planetesimal disks.


title:
Multi-Object Near-IR H-alpha Spectroscopy of z~1 star-forming galaxies
  in the HDF-N

abstract:
  We present preliminary results from a programme to obtain multi-object
near-infrared spectroscopy of galaxies at redshifts $0.7<z<1.5$. We are using
the instrument CIRPASS (the Cambridge Infra-Red PAnoramic Survey Spectrograph),
in multi-object mode, to survey H-alpha in galaxies at $z\sim1$. We aim to
address the true star formation history of the universe at this epoch:
potentially the peak period of star formation activity. H-alpha is the same
star formation measure used at low redshift, and hence we can trace star
formation without the systematic uncertainties of using different calibrators
in different redshift bins, or the extreme dust extinction in the rest-UV.
CIRPASS has been successfully demonstrated in multi-object mode on the AAT and
WHT. Here we present preliminary results from one of our fields, the Hubble
Deep Field North, observed with the WHT. With 150 fibres deployed over an
unvignetted field of $\sim15$arcmin, we have several detections of H-alpha from
star forming galaxies at $0.8<z<1.0$ and present spectra of the seven brightest
of these. By pre-selecting galaxies with redshifts such that H-alpha will
appear between the OH sky lines, we can detect star formation rates of $5
h^{-2}_{70} M_{\odot} {\rm yr}^{-1}$ ($5 \sigma$ in 3-hours, $\Omega_M=0.3$,
$\Omega_{\Lambda}=0.7$). It appears that star formation rates inferred from
H-alpha are, on average, a factor of more than two higher than those based on
the UV continuum alone.


title:
Differentially rotating magnetised neutron stars: production of toroidal
  magnetic fields

abstract:
  We initiate numerical studies of differentially rotating magnetised (proto)
neutron stars by studying - through construction from first principles - the
coupling between an assumed differential rotation and an impressed magnetic
field. For a perfect incompressible, homogeneous, non-dissipative fluid sphere
immersed in an ambient plasma, we solve the (coupled) azimuthal components of
the Navier-Stokes equation and the Maxwell induction equation. The assumed
time--independent poloidal field lines get dragged by the rotating fluid and
produce toroidal magnetic fields. Surface magnetic fields take away energy
redistributing the angular momentum to produce rigid rotation along poloidal
field lines. Due to absence of viscous dissipation, sustained torsional
oscillations are set up within the star. However, the perpetual oscillations of
neighbouring `closed' field lines get increasingly out of phase with time,
leading to structure build up as in Liu & Shapiro (2004) implying the
importance of taking into account diffusion (Spruit 1999) for realistic
modeling.


title: The BATSE 9 year histories of the brightest AGN

abstract:
  The Burst and Transient Source Experiment (BATSE) aboard CGRO monitored the
whole sky through 8 NaI(Tl) crystal scintillators sensitive in the 20 keV - 2
MeV energy band continuously from April 1991 until June 2000. Results are
presented on the long term variabilty observed in the brightest Active Galactic
Nuclei (AGN) present in the BATSE data archive. This was achieved through the
application of the Earth Occultation technique to data flat-fielded using the
BATSE Mass Model. Removal of the temporal background variations from the data
should allow a more sensitive extraction of source parameters. Analysis of the
general trends of the 9-year light curves are also presented.


title: Polar Shapelets

abstract:
  The shapelets method for image analysis is based upon the decomposition of
localised objects into a series of orthogonal components with convenient
mathematical properties. We extend the "Cartesian shapelet" formalism from
earlier work, and construct "polar shapelet" basis functions that separate an
image into components with explicit rotational symmetries. These frequently
provide a more compact parameterisation, and can be interpreted in an intuitive
way. Image manipulation in shapelet space is simplified by the concise
expressions for linear coordinate transformations; and shape measures
(including object photometry, astrometry and galaxy morphology estimators) take
a naturally elegant form. Particular attention is paid to the analysis of
astronomical survey images, and we test shapelet techniques upon real data from
the Hubble Space Telescope. We present a practical method to automatically
optimise the quality of an arbitrary shapelet decomposition in the presence of
observational noise, pixellisation and a Point-Spread Function. A central
component of this procedure is the adaptive choice of the shapelet expansion's
scale size and truncation order. A complete software package to perform
shapelet image analysis is made available on the world-wide web at
http://www.astro.caltech.edu/~rjm/shapelets/ .


title: The polarization of mm methanol masers

abstract:
  We present a survey of the polarization properties of mm-wavelength methanol
masers, comprising both classes, and transitions from 84.5 to 157.0 GHz. Linear
polarization is found in more than half of the observed objects, and circular
polarization is tentatively detected in two sources. Class I and Class II
CH_3OH masers show similar polarization properties.The largest linear
polarization is found in the 133 GHz Class I maser towards L379 (39.5 %), and
in the 157 GHz Class II maser towards G9.62+0.19 (36.7 %). The spectral
profiles of the polarization angle of Class I masers are mostly flat, except
for two sources showing a linear slope. Since the mm-line methanol masers are
expected to be weakly (or not) saturated, we suggest that the stronger
fractional polarizations found by us are enhanced by anisotropic pumping and
radiative losses. In NGC 7538, we find, for both maser classes, a good
agreement between our polarization angles, and those measured for the
submillimeter dust continuum. This can be taken as evidence for magnetic
alignment of dust grains. It is also possible that an unsaturated maser with
equally populated magnetic substates simply amplifies polarized continuum seed
radiation. For Class II masers, the polarization properties of the various
velocity components towards a given source with detectable polarization are
quite homogeneous. A possible explanation is discussed. Since methanol is
non-paramagnetic, the circular polarization of the unsaturated maser emission
can only be due to variations of the angle between the magnetic field and the
line of sight along the maser propagation path.


title:
Reconsidering the origin of the 21 micron feature: Oxides in carbon-rich
  PPNe?

abstract:
  The origin of the so-called "21 micron" feature which is especially prominent
in the spectra of some carbon-rich protoplanetary nebulae (PPNe}) is the matter
of a lively debate. A large number of potential band carriers have been
presented and discarded within the past decade. The present paper gives an
overview of the problems related to the hitherto proposed feature
identifications, including the recently suggested candidate carrier silicon
carbide. We also discuss the case for spectroscopically promising oxides.
  SiC is shown to produce a strong resonance band at 20-21 micron if coated by
a layer of silicon dioxide. At low temperatures, core-mantle particles composed
of SiC and amorphous SiO$_2$ indeed have their strongest spectral signature at
a position of 20.1 micron, which coincides with the position of the "21 micron"
emission band.
  The optical constants of another candidate carrier that has been relatively
neglected so far -- iron monoxide -- are proven to permit a fairly accurate
reproduction of the "21 micron" feature profile as well, especially when
low-temperature measurements of the infrared properties of FeO are taken into
account. As candidate carrier of the "21 micron" emission band, FeO has the
advantage of being stable against further oxidation and reduction only in a
narrow range of chemical and physical conditions, coinciding with the fact that
the feature, too, is detected in a small group of objects only. However, it is
unclear how FeO should form or survive particularly in carbon-rich PPNe.


title: Cosmological Perturbations During Radion Stabilization

abstract:
  We consider the evolution of cosmological perturbations during radion
stabilization, which we assume to happen after a period of inflation in the
early universe. Concentrating on the Randall-Sundrum brane world scenario, we
find that if matter is present both on the positive and negative tension
branes, the coupling of the radion to matter fields could have significant
impact on the evolution of the curvature perturbation and on the production of
entropy perturbations. We investigate both the case of a long-lived and
short-lived radion and outline similarities and differences to the curvaton
scenario.


title:
Design and construction of the IMACS-IFU, a 2000-element integral field
  unit

abstract:
  The IMACS-IFU is an Integral Field Unit built for the IMACS spectrograph at
the Magellan-I-Telescope at Las Campanas Observatory. It consists of two
rectangular fields of 5 by 7 arcseconds, separated by roughly one arcminute.
With a total number of 2000 spatial elements it is the second largest
fiber-lenslet based IFU worldwide, working in a wavelength range between 400
and 900 nm. Due to the equally sized fields classical background subtraction,
beam switching and shuffling are possible observation techniques. One
particular design challenge was the single, half a metre long curved slit in
combination with a non telecentric output. Besides the construction some
preliminary results are described.


title: Dark energy and supermassive black holes

abstract:
  This paper deals with a cosmological model in which the universe is filled
with tachyon dark energy in order to describe current and future accelerating
expansion. We obtain that the simplest condition for the regime of phantom
energy to occur in this scenario is that the scalar field be Wick rotated to
imaginary values which correspond to an axionic field classically. By
introducing analytical expressions for the scale factor or the Hubble parameter
that satisfy all constraint equations of the used models we show that such
models describe universes which may develop a big rip singularity in the finite
future. It is argued that, contrary to a recent claim, the entropy for a
universe filled with dark energy is definite positive even on the phantom
regime where the universe would instead acquire a negative temperature. It is
also seen that, whichever the fate of the tachyonic accelerating universe, it
will be stable to any fluctuations of the scalar field, and that since the
considered models have all an imaginary sound speed, any overdense regions will
undergo an accelerate collapse leading rapidly to formation of giant black
holes. Finally the conjecture is advanced that these black holes may be the
supermassive black holes that most galaxies harbor at their center.


title: Obscuration and Origin of Nuclear X-ray emission in FR I Radio Galaxies

abstract:
  We present X-ray observations of the nuclear region of 25 Fanaroff-Riley I
radio galaxies from the 3CRR and B2 catalogs, using data from the Chandra and
XMM archives. We find the presence of a X-ray Central Compact Core (CCCX) in
13/25 sources, in 3/25 sources the detection of a CCCX is uncertain, while in
the remaining 9/25 sources no CCCX is found. All the sources are embedded in a
diffuse soft X-ray component, generally on kpc-scales, which is in agreement
with the halo of the host galaxy and/or with the intracluster medium. The X-ray
spectra of the cores are described by a power law with photon indices Gamma=1.1
- 2.6. In 8 sources excess absorption over the Galactic value is detected, with
rest-frame column densities N_H^z ~ 10^20 - 10^21 cm^-2; thus, we confirm the
previous claim based on optical data that most FRI radio galaxies lack a
standard optically-thick torus. We find significant correlations between the
X-ray core luminosity and the radio and optical luminosities, suggesting that
at least a fraction of the X-ray emission originates in a jet; however, the
origin of the X-rays remains ambiguous. If the X-ray emission is entirely
attributed to an isotropic, accretion-related component, we find very small
Eddington ratios, L_bol/L_Edd ~ 10^-3 - 10^-8, and we calculate the radiative
efficiency to be eta ~ 10^-2 - 10^-6, based on the Bondi accretion rates from
the spatial analysis. This suggests that radiatively inefficient accretion
flows are present in the cores of low-power radio galaxies.


title:
Reconstructing Cepheid Light Curve with Fourier Techniques II: Catalogue
  of the Fourier Parameters for OGLE LMC Fundamental Mode Cepheids

abstract:
  In this paper we present a catalogue of the Fourier parameters for the light
curves of Large Magellanic Cloud fundamental mode Cepheids in the OGLE
database. These Fourier parameters are obtained with a simulated annealing
method. The photometric data are mainly fit with 4th to 8th-order Fourier
expansion, though some of the long period Cepheids require up to a 12th-order
fit to the data.


title:
High Energy Observations of XRF 030723: Evidence for an Off-axis
  Gamma-Ray Burst?

abstract:
  We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-ray
Monitor/French Gamma Telescope observations of XRF030723 along with
observations of the XRF afterglow made using the 6.5m Magellan Clay telescope
and the Chandra X-ray Observatory. The observed peak energy E_pk_obs of the nu
F_nu burst spectrum is found to lie within (or below) the WXM 2-25 keV passband
at 98.5% confidence, and no counts are detected above 30 keV. Our best fit
value is E_pk_obs=8.4+3.5/-3.4 keV. The ratio of X-ray to Gamma-ray flux for
the burst follows a correlation found for GRBs observed with HETE-2, and the
duration of the burst is similar to that typical of long-duration GRBs. If we
require that the burst isotropic equivalent energy E_iso and E_pk_rest satisfy
the relation discovered by Amati et al. (2002), a redshift of z=0.38+0.36/-0.18
can be determined, in agreement with constraints determined from optical
observations. We are able to fit the X-ray afterglow spectrum and to measure
its temporal fade. Although the best-fit fade is shallower than the concurrent
fade in the optical, the spectral similarity between the two bands indicates
that the X-ray fade may actually trace the optical fade. If this is the case,
the late time rebrightening observed in the optical cannot be due to a
supernova bump. We interpret the prompt and afterglow X-ray emission as arising
from a jetted GRB observed off-axis and possibly viewed through a complex
circumburst medium due to a progenitor wind.


title: Studying Distant Infrared-Luminous Galaxies with Spitzer and Hubble

abstract:
  New surveys with the Spitzer space telescope identify distant star-forming
and active galaxies by their strong emission at far-infrared wavelengths, which
provides strong constraints on these galaxies' bolometric energy. Using early
results from Spitzer surveys at 24 micron, we argue that the faint sources
correspond to the existence of a population of infrared-luminous galaxies at z
> 1 that are not expected from predictions based on previous observations from
ISO and IRAS. Combining Spitzer images with deep ground-based optical and
Hubble Space Telescope imaging, we discuss the properties of galaxies selected
at 24 micron in the region of the Chandra Deep Field South, including redshift
and morphological distributions. Galaxies with z < 1 constitute roughly half of
the faint 24 micron sources. Infrared-luminous galaxies at these redshifts span
a wide variety of normal to strongly interacting/merging morphologies, which
suggests that a range of mechanisms produce infrared activity. Large-area,
joint surveys between Spitzer and HST are needed to understand the complex
relation between galaxy morphology, structure, environment and activity level,
and how this evolves with cosmic time. We briefly discuss strategies for
constructing surveys to maximize the legacy of these missions.


title: Primordial Bispectrum Information from CMB Polarization

abstract:
  After the precise observations of the Cosmic Microwave Background (CMB)
anisotropy power spectrum, attention is now being focused on the higher order
statistics of the CMB anisotropies. Since linear evolution preserves the
statistical properties of the initial conditions, observed non-Gaussianity of
the CMB will mirror primordial non-Gaussianity. Single field slow-roll
inflation robustly predicts negligible non-Gaussianity so an indication of
non-Gaussianity will suggest alternative scenarios need to be considered. In
this paper we calculate the information on primordial non-Gaussianity encoded
in the polarization of the CMB. After deriving the optimal weights for a cubic
estimator we evaluate the Signal-to-Noise ratio of the estimator for WMAP,
Planck and an ideal cosmic variance limited experiment. We find that when the
experiment can observe CMB polarization with good sensitivity, the sensitivity
to primordial non-Gaussianity increases by roughly a factor of two. We also
test the weakly non-Gaussian assumption used to derive the optimal weight
factor by calculating the degradation factor produced by the gravitational
lensing induced connected four-point function. The physical scales in the
radiative transfer functions are largely irrelevant for the constraints on the
primordial non-Gaussianity. We show that the total (S/N)^2 is simply
proportional to the number of observed pixels on the sky.


title: Measuring Dark Energy Clustering with CMB-Galaxy Correlations

abstract:
  The integrated Sachs-Wolfe (ISW) effect in the cosmic microwave background
(CMB) as measured through its correlation with galaxies provides a unique
opportunity to study the dynamics of the dark energy through its large scale
clustering properties. Ultimately, a deep all-sky galaxy survey out to z~2 can
make a 10sigma or ~10% measurement of the correlation and limit ~3% changes in
the gravitational potential or total density fluctuation due to dark energy
clustering on the Gpc scale. A canonical single scalar field or quintessence
model predicts that these clustering effects will appear on the horizon scale
with a strength that reflects the evolution of the dark energy density. In
terms of a constant equation of state, this would allow tests of the
quintessence prediction for models where |1+w| > 0.05.


title:
Measurement of gravitational spin-orbit coupling in a binary pulsar
  system

abstract:
  In relativistic gravity, a spinning pulsar will precess as it orbits a
compact companion star. We have measured the effect of such precession on the
average shape and polarization of the radiation from PSR B1534+12. We have also
detected, with limited precision, special-relativistic aberration of the
revolving pulsar beam due to orbital motion. Our observations fix the system
geometry, including the misalignment between the spin and orbital angular
momenta, and yield a measurement of the precession timescale consistent with
the predictions of General Relativity.