title:
Preparing the COROT space mission: new variable stars in the galactic
  Anticenter direction

abstract:
  The activities related to the preparation of the asteroseismic, photometric
space mission COROT are described. Photoelectric observations, wide--field CCD
photometry, uvbyB calibrations and further time--series have been obtained at
different observatories and telescopes. They have been planned to complete the
COROT programme in the direction of the galactic Anticenter. In addition to
suitable asteroseismic targets covering the different evolutionary stages
between ZAMS and TAMS, we discovered several other variable stars, both
pulsating and geometrical. We compared results on the incidence of variability
in the galactic Center and Anticenter directions. Physical parameters have been
obtained and evolutionary tracks fitting them have been calculated. The
peculiarities of some individual stars alre pointed out. Paper based on
observations collected at the San Pedro Martir, Sierra Nevada, Teide, La Silla,
Haute-Provence and Roque de Los Muchachos (Telescopio Nazionale Galileo and
Mercator telescopes) observatories.


title:
Evidence for an Untruncated Accretion Disk in the Broad-Line Radio
  Galaxy 4C+74.26

abstract:
  We present evidence for a broad, ionized Fe K line in the XMM-Newton spectrum
of the broad-line radio galaxy (BLRG) 4C+74.26. This is the first indication
that the innermost regions of the accretion flow in BLRGs contain thin,
radiatively efficient disks. Analysis of the 35 ks XMM-Newton observation finds
a broad line with an inner radius close to the innermost stable circular orbit
for a maximally spinning black hole. The outer radius of the relativistic line
is also found to be within 10 gravitational radii. The Fe K line profile gives
an inclination angle of ~40 degrees, consistent with the radio limit. There are
two narrow components to the Fe K complex: one at 6.4 keV from neutral Fe, and
one at 6.2 keV. These may form the blue and red horns of a diskline from
farther out on the disk, but a longer observation is required to confirm this
hypothesis. We discuss the implications of this observation for models of jet
production, and suggest that BLRGs and radio-loud quasars will have larger than
average black hole masses, thus resulting in thicker accretion flows close to
the black hole.


title:
Low-Frequency Gravitational Radiation from Coalescing Massive Black
  Holes

abstract:
  We compute the expected low-frequency gravitational wave signal from
coalescing massive black hole (MBH) binaries at the center of galaxies. We
follow the merging history of halos and associated holes via cosmological Monte
Carlo realizations of the merger hierarchy from early times to the present in a
LCDM cosmology. MBHs get incorporated through a series of mergers into larger
and larger halos, sink to the centre owing to dynamical friction, accrete a
fraction of the gas in the merger remnant to become more massive, and form a
binary system. Stellar dynamical processes dominates the orbital evolution of
the binary at large separations, while gravitational wave emission takes over
at small radii, causing the final coalescence of the system. We discuss the
observability of inspiraling MBH binaries by a low-frequency gravitational wave
experiment such as the planned Laser Interferometer Space Antenna (LISA),
discriminating between resolvable sources and unresolved confusion noise. Over
a 3-year observing period LISA should resolve this GWB into discrete sources,
detecting ~90 individual events above a S/N=5 confidence level, while expected
confusion noise is well below planned LISA capabilities.


title: On the Dynamics of Suddenly Heated Accretion Disks around Neutron Stars

abstract:
  Type I X-ray bursts and superbursts on neutron stars release sudden and
intense radiation fields into their surroundings. Here, we consider the
possible effects of these powerful explosions on the structure of the accretion
disk. The goal is to account for the apparent evolution of the innermost
regions of the accretion disk around 4U 1820-30 during a superburst. Three
different processes are considered in detail: radiatively or thermally driven
outflows, inflow due to Poynting-Robertson drag, and a structural change to the
disk by X-ray heating. Radiatively driven winds with large column densities can
be launched from the inner disk, but only for L/L_{Edd} >~ 1, which is expected
to be obtained only at the onset of the burst. Furthermore, the predicted mass
outflow rate is less than the accretion rate in 4U 1820-30. Estimates of the
Poynting-Robertson or radiative drag timescale shows that it is a very
efficient means of removing angular momentum from the gas. However, the
analytical results are likely only applicable at the innermost edge of the
disk. X-ray heating gives a change in the disk scale height that is correlated
with the blackbody temperature, as seen in the evolution during the 4U 1820-30
superburst. If this change in the scale height can alter the surface density,
then the viscous time (with \alpha ~ 0.03-0.2) is the closest match to the 4U
1820-30 results. We expect, however, that all three processes are likely
ongoing when an accretion disk is subject to a sudden heating event.
Ultimately, a numerical simulation of a disk around a bursting neutron star is
required to determine the exact response of the disk. Magnetic truncation of
the accretion flow is also considered and applied to the 4U 1820-30 X-ray
reflection results.


title:
Exceptional H_2 emission in the Antennae galaxies: Pre-starburst shocks
  from the galaxy collision

abstract:
  The collision of gas-rich galaxies is believed to produce strong shocks
between their gas clouds which cause the onset of the observed bursts of
extended star formation. However, the so far observed shock signatures in
colliding galaxies can be explained essentially by winds from already existing
massive stars and supernovae and thus do not give any evidence for an
outstanding pre-starburst phase. Either pre-starburst gas shocks are too
short-lived to be detected or one has to modify our perception of colliding
galaxies. A dedicated analysis of ISOCAM-CVF mid-infrared spectral maps led us
to the discovery of exceptional H_2 v=0-0 S(3) lambda = 9.66 um line emission
from the "Antennae" galaxy pair, which is at an early stage of galaxy
collision. Its H_2 line luminosity, normalized by the far-infrared luminosity,
exceeds that of all other known galaxies and the strongest H_2 emission is
spatially displaced from the known starbursts regions. This implies that most
of the excited H_2 gas in the Antennae must be shocked due to the collision of
the two galaxies. These observations indicate that the outstanding phase of
pre-starburst shocks exists, and that they might be a key to our understanding
of the formation of the first proto-galaxies.


title:
Do observations prove that cosmological neutrinos are thermally
  distributed?

abstract:
  It is usually assumed that relic neutrinos possess a Fermi-Dirac
distribution, acquired during thermal equilibrium in the Early Universe.
However, various mechanisms could introduce strong distortions in this
distribution. We perform a Bayesian likelihood analysis including the first
moments of the three active neutrino distributions as free parameters, and show
that current cosmological observations of light element abundances, Cosmic
Microwave Background (CMB) anisotropies and Large Scale Structures (LSS) are
compatible with very large deviations from the standard picture. We also
calculate the bounds on non-thermal distortions which can be expected from
future observations, and stress that CMB and LSS data alone will not be
sensitive enough in order to distinguish between non-thermal distortions in the
neutrino sector and extra relativistic degrees of freedom. This degeneracy
could be removed by additional constraints from primordial nucleosynthesis or
independent neutrino mass scale measurements.


title: The Phase-Space Parameters of Brightest Halo Galaxies

abstract:
  The brightest galaxy in a dark matter halo is expected to reside at rest at
the center of the halo. In this paper we test this `Central Galaxy Paradigm'
using group catalogues extracted from the 2dFGRS and the SDSS. For each group
we compute a parameter, R, defined as the difference between the velocity of
the brightest group galaxy and the average velocity of the other group members
(hereafter satellites), normalized by the unbiased estimator of the velocity
dispersion of the satellite galaxies. Using detailed mock galaxy redshift
surveys, we show that the central galaxy paradigm is inconsistent with the data
at high confidence, and that instead the brightest halo galaxies have a
specific kinetic energy that is about 25 percent of that of the satellites.
This indicates that either central galaxies reside at the minimum of the dark
matter potential, but that the halo itself is not yet fully relaxed, or, that
the halo is relaxed, but that the central galaxy oscillates in its potential
well. The former is consistent with the fact that we find a weak hint that the
velocity bias of brightest halo galaxies is larger in more massive haloes,
while the latter may be indicative of cored, rather than cusped, dark matter
haloes. We discuss several implications of these findings, including mass
estimates based on satellite kinematics, strong gravitational lensing, halo
occupation models, and the frequency and longevity of lopsidedness in disk
galaxies.


title: Old Globular Clusters Masquerading as Young in NGC 4365?

abstract:
  High signal-to-noise, low-resolution spectra have been obtained for 22
globular clusters (GCs) in NGC 4365. Some of these were selected as probable
representatives of an intermediate-age (2-5 Gyr), extremely metal-rich GC
subpopulation. The presence of such a subpopulation had been inferred from the
unusual optical and near-IR color distributions of GCs in this otherwise
typical Virgo elliptical galaxy. However, ages derived from Lick indices are
consistent with uniformly old mean ages for all GCs in our sample. The
metallicities of the clusters show some evidence for a trimodal distribution.
The most metal-poor and metal-rich peaks are consistent with the values
expected for an elliptical galaxy of this luminosity, but there appears to be
an additional, intermediate-metallicity peak lying between them. New Hubble
Space Telescope photometry is consistent with this result. A plausible scenario
is that in earlier data these three peaks merged into a single broad
distribution. Our results suggest that it is difficult to identify
intermediate-age GC subpopulations solely with photometry, even when both
optical and near-infrared colors are used.


title:
The Discovery of the Optical and Near-IR Afterglows of the First Swift
  Gamma-Ray Bursts

abstract:
  We present optical and near-infrared searches for afterglow emission from the
first four Swift bursts with accurate positions from the X-ray Telescope (XRT).
Using telescopes at Las Campanas, Keck, and Palomar observatories we rapidly
identified and followed up afterglows for three of the four bursts. The burst
positions were also observed with the Very Large Array, but no radio afterglow
emission was detected. The optical/NIR afterglows are fainter than about 75% of
all afterglows detected to date, with GRB 050126 being the faintest, and were
identified thanks to accurate and rapid positions from the XRT and rapid
response with >1-m telescopes. This suggests that the fraction of dust-obscured
bursts is small, <10% when combined with afterglows localized by the HETE-2
Soft X-ray Camera. The X-ray fluxes are typical of the known population, with
the exception of GRB 050126 which has the faintest X-ray afterglow to date
(normalized to t=10 hr), and was detected thanks to a response time of only 130
s after the burst. Finally, we find that all three optical/NIR afterglows are
located <2 arcsec away from the nominal XRT positions, suggesting that the XRT
is capable of delivering highly accurate positions, which will revolutionize
afterglow studies.


title: Lensed CMB simulation and parameter estimation

abstract:
  Modelling of the weak lensing of the CMB will be crucial to obtain correct
cosmological parameter constraints from forthcoming precision CMB anisotropy
observations. The lensing affects the power spectrum as well as inducing
non-Gaussianities. We discuss the simulation of full sky CMB maps in the weak
lensing approximation and describe a fast numerical code. The series expansion
in the deflection angle cannot be used to simulate accurate CMB maps, so a
pixel remapping must be used. For parameter estimation accounting for the
change in the power spectrum but assuming Gaussianity is sufficient to obtain
accurate results up to Planck sensitivity using current tools. A fuller
analysis may be required to obtain accurate error estimates and for more
sensitive observations. We demonstrate a simple full sky simulation and
subsequent parameter estimation at Planck-like sensitivity. The lensed CMB
simulation and parameter estimation codes are publicly available.


title: Neutrino-Dominated Accretion and Supernovae

abstract:
  We suggest that part of the infalling material during the core-collapse of a
massive star goes into orbit around the compact core to form a hot, dense,
centrifugally-supported accretion disk whose evolution is strongly influenced
by neutrino interactions. Under a wide range of conditions, this
neutrino-dominated accretion flow will be advection-dominated and will develop
a substantial outflowing wind. We estimate the energy carried out in the wind
and find that it exceeds $10^{50}$ erg for a wide range of parameters and even
exceeds 10^{51} erg for reasonable parameter choices. We propose that the wind
energy will revive a stalled shock and will help produce a successful supernova
explosion. We discuss the role of the disk wind in both prompt and delayed
explosions. While both scenarios are feasible, we suggest that a delayed
explosion is more likely, and perhaps even unavoidable. Finally, we suggest
that the disk wind may be a natural site for r-process nucleosynthesis.


title: Magnetically limited X-ray filaments in young SNR

abstract:
  We discuss the damping of strong magnetic turbulence downstream of the
forward shock of young supernova remnants (SNR). We find that strong magnetic
fields, that have been produced by the streaming instability in the upstream
region of the shock, or by other kinetic instabilities at the shock, will be
efficiently reduced, so the region of enhanced magnetic field strength would
typically have a thickness of the order l_d=(10^{16}-10^{17}) cm. The
non-thermal X-ray filaments observed in young SNR are thus likely limited by
the magnetic field and not by the energy losses of the radiating electrons.
Consequently the thickness of the filaments would not be a measure of the
magnetic field strength and claims of efficient cosmic-ray acceleration on
account of a run-away streaming instability appear premature.


title: The persistence of the universal halo profiles

abstract:
  Simple simulations suggest that the phase space structure of haloes
identified in cosmological calculations is invariant under the dynamics induced
by sinking substructure satellites -- the background expands so as to leave the
total distribution unchanged. We use a Fokker-Planck formulation to show that
this is the case. The solutions obtained are valid for any mass spectrum of
substructure, because the governing equation is linear in their mass weighed
phase space distribution. If the clumps are considered solid, an exchange of
poulations takes the form of an exponential instability, with characteristic
timescale of the order of the dynamical friction time, leading to a low energy
cutoff in the distribution function of the background and a constant density
core. We show that there are long lived solutions with such a cutoff. They
approximate a situation whereas the clumps are made of dense baryonic material.
When stripping is important, as in the case of dissipationless substructure, it
is likely that this situation is reversed -- the cutoff is now in the clump
distribution function. A simple description suggests that this renders
equilibria even more long lived. The results of this paper suggest that halo
profiles similar to those found in dissipationless cosmological simulations are
approximately invariant under the interaction induced by the presence of
substructure satellites -- a necessary condition for the observed
`universality'. In addition, the total profile, including baryons, should also
be invariant; provided the latter are initially in the form of dense clumps,
whose distribution follows that of the dark matter.


title: The Beaming Factor and Other Open Questions In GRB Jets

abstract:
  I review several central open questions concerning GRB Jets. 1) I discuss a
new estimates of the beaming correction for the rate of GRBs ~ 75 +- 20. 2) I
discuss the universal structured jet (USJ) model and conclude that while jets
might be structured they are less likely to be universal. 3) I discuss recent
observations of a sideways expansion of a GRB afterglow and compare these with
current hydrodynamics simulations of jet evolution. 4) I discuss the
implications of resent outliers to the energy-angle relation.


title: A Unified Model for Gamma-Ray Bursts

abstract:
  A possible unified model of short and long gamma-ray bursts (GRBs), X-ray
rich GRBs, and X-ray flashes is proposed. It is assumed that the jet of a GRB
consists of many emitting sub-shells (i.e., an inhomogeneous jet model). The
multiplicity of the sub-shells along a line of sight n_s is an important
parameter. If n_s is large (>>1) the event looks like a long GRB, while if
n_s=1, the event looks like a short GRB. Finally, when n_s=0, the event looks
like an X-ray flash or an X-ray rich GRB. Furthermore, our model may also
explain the bimodal distributions of T90 duration of BATSE-GRBs. Clearly, our
model predicts that short GRBs should be associated with energetic SNe.


title:
Early GRB afterglow from a reverse shock as a tracer of the prompt
  gamma-ray light curve

abstract:
  We discuss the optical and radio early afterglow emission of the reverse
shock that crosses a baryonic ejecta as it interacts with the external
interstellar medium (ISM). We show that the peak of the optical flash divides
the light curve of the reverse shock into two distinctive phases. The emission
after the peak depends weakly on the initial conditions of the ejecta and
therefore it can be used as an identifiable signature of a reverse shock
emission. On the other hand, the emission before the optical peak is highly
sensitive to the initial conditions and therefore can be used to investigate
the initial hydrodynamic profile of the ejecta. In particular, if the prompt
$\gamma$-ray emission results from internal shocks, the early reverse shock
emission should resemble a smoothed version of the prompt $\gamma$-ray light
curve.


title: Dynamic Meteorology at the Photosphere of HD 209458b

abstract:
  We calculate the meteorology of the close-in transiting extrasolar planet HD
209458b using a global, three-dimensional atmospheric circulation model.
Dynamics are driven by perpetual irradiation of one hemisphere of this tidally
locked planet. The simulation predicts global temperature contrasts of ~500 K
at the photosphere and the development of a steady superrotating jet. The jet
extends from the equator to mid-latitudes and from the top model layer at 1
mbar down to 10 bars at the base of the heated region. Wind velocities near the
equator exceed 4 km/s at 300 mbar. The hottest regions of the atmosphere are
blown downstream from the substellar point by 60 degrees of longitude. We
predict from these results a factor of ~2 ratio between the maximum and minimum
observed radiation from the planet over a full orbital period, with peak
infrared emission preceding the time of the secondary eclipse by ~14 hours.


title:
Nonlinear Perpendicular Diffusion in Strong Turbulent Electromagnetic
  Fields

abstract:
  A nonlinear description for perpendicular particle diffusion in strong
electromagnetic fluctuations is developed by using the fundamental
Newton-Lorentz equation. Although not based on the same approach, the recently
presented nonlinear guiding center (NLGC) theory is recovered as a special
case. The approach used here is rather based on the argument that a well
defined particle gyromotion does not exist in strong fluctuations than on the
assumption that the particle gyrocenter follows magnetic field lines which
themselves separate diffusively. The assumption of a guiding center motion and
the diffusive separation of magnetic field lines is absolutely central to the
NLGC theory. It is argued that the NLGC result should provide most accurate
results for strong fluctuations. Furthermore, as a direct consequence of the
particle equation of motion, it is shown that particle diffusion in one
perpendicular direction is governed by the fluctuations in the other normal
direction. This results contradicts the NLGC result, where perpendicular
diffusion is triggered by fluctuations in the same direction. This is of
particular interest for anisotropic perpendicular diffusion in a
non-axisymmetric turbulence. Future numerical simulation results for
non-axisymmetric magnetic turbulence and their comparison with the approach
presented here and the NLGC theory have to provide an answer whether particle
diffusion in one perpendicular direction is governed by the fluctuations in the
other normal direction or by fluctuations in the same direction.


title: An atlas of Calcium triplet spectra of active galaxies

abstract:
  We present a spectroscopic atlas of active galactic nuclei covering the
region around the 8498, 8542, 8662 Calcium triplet (CaT) lines. The sample
comprises 78 objects, divided into 43 Seyfert 2s, 26 Seyfert 1s, 3 Starburst
and 6 normal galaxies. The spectra pertain to the inner ~300 pc in radius, and
thus sample the central kinematics and stellar populations of active galaxies.
The data are used to measure stellar velocity dispersions (sigma_star) both
with cross-correlation and direct fitting methods. These measurements are found
to be in good agreement with each-other and with those in previous studies for
objects in common. The CaT equivalent width is also measured. We find average
values and sample dispersions of W_CaT of 4.6+/-2.0, 7.0 and 7.7+/-1.0
angstrons for Seyfert 1s, Seyfert 2s and normal galaxies, respectively. We
further present an atlas of [SIII]\lambda 9069 emission line profiles for a
subset of 40 galaxies. These data are analyzed in a companion paper which
addresses the connection between stellar and Narrow Line Region kinematics, the
behaviour of the CaT equivalent width as a function of sigma_star, activity
type and stellar population properties.


title: Centrally condensed turbulent cores: Massive stars or fragmentation?

abstract:
  We present numerical investigations into the formation of massive stars from
centrally condensed turbulent cores. The results of five hydrodynamical
simulations are described, following the collapse of the core, fragmentation
and the formation of small clusters of protostars. We generate two different
initial turbulent velocity fields corresponding to power-law spectra with power
varying as k^{-4} and k^{-3.5}, and apply two different initial core radii.
Calculations are included for both completely isothermal collapse, and a
non-isothermal equation of state above a critical density 10^{-14}gcm^{-3}. Our
calculations reveal the preference of fragmentation over monolithic star
formation in turbulent cores. Fragmentation was prevalent in all the isothermal
cases. Although disc fragmentation was largely suppressed in the non-isothermal
runs due to the small dynamic range between the initial density and the
critical density, our results show that some fragmentation still persisted.
This is inconsistent with previous suggestions that turbulent cores result in
the formation of a single massive star. We conclude that turbulence cannot be
measured as an isotropic pressure term.


title: Can CCM law properly represent all extinction curves?

abstract:
  We present the analysis of a large sample of lines of sight with extinction
curves covering wavelength range from near-infrared (NIR) to ultraviolet (UV).
We derive total to selective extinction ratios based on the Cardelli, Clayton
and Mathis (1989, CCM) law, which is typically used to fit the extinction data
both for diffuse and dense interstellar medium. We conclude that the CCM law is
able to fit most of the extinction curves in our sample. We divide the
remaining lines of sight with peculiar extinction into two groups according to
two main behaviors: a) the optical/IR or/and UV wavelength region cannot be
reproduced by the CCM formula; b) the optical/NIR and UV extinction data are
best fit by the CCM law with different values of R_V. We present examples of
such curves. The study of both types of peculiar cases can help us to learn
about the physical processes that affect dust in the interstellar medium, e.g.,
formation of mantles on the surface of grains, evaporation, growing or
shattering.


title:
On Statistical Lensing and the Anti-Correlation Between 2dF QSOs and
  Foreground Galaxies

abstract:
  We cross-correlate APM and SDSS galaxies with background QSOs from the 2dF
QSO Redshift Survey, and detect a significant (2.8sigma) anti-correlation. The
lack of a signal between 2dF stars and our galaxy samples suggests the
anti-correlation is not due to a systematic error. The possibility that dust in
the foreground galaxies could produce the anti-correlation is marginally
rejected, at the 2sigma level through consideration of QSO colours. It is
possible that dust that obscures QSOs without reddening them, or preferentially
discards reddened QSOs from the 2QZ sample, could produce such an
anti-correlation, however, such models are at odds with the positive QSO-galaxy
correlations found at bright magnitudes by other authors. Our detection of a
galaxy-QSO anti-correlation is consistent with statistical lensing theory. When
combined with earlier results that have reported a positive galaxy-QSO
correlation, a consistent, compelling picture emerges that spans faint and
bright QSO samples showing positive or negative correlations according to the
QSO N(m) slope. We find that galaxies are highly anti-biased on small scales.
We consider two models that use different descriptions of the lensing matter
and find they yield consistent predictions for the strength of galaxy bias on
0.1Mpc/h scales of b~0.1 (for LCDM). Whilst the slope of our power-law fit to
the QSO-galaxy cross-correlation does not rule out linear bias, when we compare
our measurement of b on 100 kpc/h scales to independent methods that determine
b~1 on Mpc/h scales, we conclude that bias, on these small scales, is
scale-dependent. These results indicate more mass, at least on the 100 kpc/h
scales probed, than predicted by simple LCDM biasing prescriptions, and can
thus constrain halo occupation models of the galaxy distribution.


title: The Galaxy Populations of Double Cluster RX J1053.7+5735 at z=1.13

abstract:
  We present a study of the galaxy population in the cluster RX J1053.7+5735,
one of the most distant X-ray selected clusters of galaxies, which also shows
an unusual double-lobed X-ray morphology, indicative of a possible equal-mass
cluster merger. Using Keck-DEIMOS spectroscopic observations of galaxies in the
2x1.5 arcmin region surrounding RX J1053.7+5735, we secured redshifts for six
galaxies in the range 1.129 < z < 1.139, with a mean redshift <z>=1.134. The
mean redshift agrees well with the cluster X-ray redshift previously estimated
from the cluster X-ray Fe-K line, confirming the presence of a cluster at
z~1.135. Galaxies with concordant redshifts are located in both eastern and
western sub-clusters of the double cluster structure, indicating that both
sub-clusters are at similar redshifts. This result is also consistent with a
previous claim that both eastern and western X-ray lobes have similar X-ray
redshifts. Based on their separation of ~ 250 kpc/h, these results support the
interpretation that RX J1053.7+5735 is an equal-mass cluster merger taken place
at z ~ 1, although further direct evidence for dynamical state of the cluster
is needed for a more definitive statement about the cluster merging state. The
six galaxies have a line-of-sight velocity dispersion = 650 km/s. All six
galaxies show clear absorption features of CaII H & K, and several Balmer
lines, typical of early galaxies at the present epoch, in agreement with their
I-K colors. A color-magnitude diagram, constructed from deep optical/NIR
observations of the RX J1053.7+5735 field, shows a clear red color sequence.
There is an indication that the red sequence in RX J1053.7+5735 lies ~ 0.3 to
the blue of the Coma line, qualitatively consistent with previous studies
investigating other clusters at z ~ 1.


title: A Chandra View of the Anomalous Half-Merger NGC520

abstract:
  (abridged) High spatial and spectral resolution Chandra X-ray observations of
the anomalous merging galaxy NGC520, a similarly-evolved system to the
well-known Antennae galaxies, are presented here. Of great interest is the fact
that NGC520, on account of it being due to the result of an encounter between
one gas-rich disk and one gas-poor disk, appears in X-rays to be only 'half a
merger'; Whereas a ULX lies at the primary (SE), more-massive nucleus, no
sources are seen at the secondary nucleus. Whereas what appears to be a
starburst-driven galactic wind is seen outflowing perpendicular to the
molecular disk surrounding the primary nucleus, no such diffuse structure is
seen anywhere near the secondary nucleus. Comparing the X-ray properties with
those of other merging galaxies, one sees that, relative to its SFR, the number
of ULXs seen within the system is rather small. Similarly the total X-ray
luminosity and the fraction of this emission that appears diffuse are both a
factor ~2 less than that expected based on NGC520's evolutionary merger stage.
15 X-ray sources are detected within the system, including a small number of
bright ULXs that flatten the source XLF to a level similar to that of the
Antennae and other mergers. Lastly, to see what appears to be a
starburst-driven diffuse galactic wind, with a spectrum entirely consistent
with that of other known galactic winds, though unusually, emanating from only
one of the nuclei, is a surprise, given that one might have expected such
structures to have distorted very quickly in such a rapidly evolving
environment. The wind is larger and more massive than features seen in
evolutionarily earlier systems (eg the Mice), but smaller and less massive than
as seen in later systems (eg the Antennae), or classic starbursts.


title: HST/NICMOS observations of a proto-brown dwarf candidate

abstract:
  We present deep HST/NICMOS observations peering through the outflow cavity of
the protostellar candidate IRAS 04381+2540 in the Taurus Molecular Cloud-1. A
young stellar object as central source, a jet and a very faint and close (0.6")
companion are identified. The primary and the companion have similar colours,
consistent with strong reddening. We argue that the companion is neither a
shock-excited knot nor a background star. The colour/magnitude information
predicts a substellar upper mass limit for the companion, but the final
confirmation will require spectroscopic information. Because of its geometry,
young age and its rare low-mass companion, this system is likely to provide a
unique insight into the formation of brown dwarfs.


title: The Birth of High Mass Stars: Accretion and/or Mergers?

abstract:
  The observational consequences of the merger scenario for massive star
formation are explored and contrasted with the gradual accumulation of mass by
accretion. Protostellar mergers may produce high luminosity infrared flares
lasting years to centuries followed by a luminosity decline on the
Kelvin-Helmholtz time-scale of the merger product. Mergers may be surrounded by
thick tori of expanding debris, impulsive wide-angle outflows, and shock
induced maser and radio continuum emission. Collision products are expected to
have fast stellar rotation and a large multiplicity fraction. Close encounters
or mergers will produce circumstellar debris disks with an orientation that
differs form that of a pre-existing disk. The extremely rare merger of two
stars close to the upper-mass end of the IMF may be a possible pathway to
hypernova generated gamma-ray bursters. While accretional growth can lead to
the formation of massive stars in isolation or in loose clusters, mergers can
only occur in high-density cluster environments. It is proposed that the
outflow emerging from the OMC1 core in the Orion molecular cloud was produced
by a protostellar merger that released between $10^{48}$ to $10^{49}$ ergs less
than a thousand years ago.


title: Correspondence principle between spherical and Euclidean wavelets

abstract:
  Wavelets on the sphere are reintroduced and further developed independently
of the original group theoretic formalism, in an equivalent, but more
straightforward approach. These developments are motivated by the interest of
the scale-space analysis of the cosmic microwave background (CMB) anisotropies
on the sky. A new, self-consistent, and practical approach to the wavelet
filtering on the sphere is developed. It is also established that the inverse
stereographic projection of a wavelet on the plane (i.e. Euclidean wavelet)
leads to a wavelet on the sphere (i.e. spherical wavelet). This new
correspondence principle simplifies the construction of wavelets on the sphere
and allows to transfer onto the sphere properties of wavelets on the plane. In
that regard, we define and develop the notions of directionality and
steerability of filters on the sphere. In the context of the CMB analysis,
these notions are important tools for the identification of local directional
features in the wavelet coefficients of the signal, and for their
interpretation as possible signatures of non-gaussianity, statistical
anisotropy, or foreground emission. But the generic results exposed may find
numerous applications beyond cosmology and astrophysics.


title:
Early chemical enrichment of the universe and the role of very massive
  pop III stars

abstract:
  In this paper the role of very massive pop III stars in the chemical
enrichment of the early universe is discussed. We first compare our predictions
with the abundance ratios measured in the high redshift Lyman-alpha forest to
check whether they are compatible with the values predicted by assuming that
the early universe was enriched by massive pop III stars. We conclude that to
explain the observed C/Si ratio in the intergalactic medium, a contribution
from pop II stars to carbon enrichment is necessary, already at redshift z=5.
We then evaluate the number of Pair-Instability Supernovae (SN_(gamma gamma))
required to enrich the universe to the critical metallicity Z_cr, i.e. the
metallicity value which causes the transition from a very massive star regime
(m > 100 M_sun) to a lower mass regime, similar to the one characteristic of
the present time (m < 100 M_sun). It is found that between 110 and 115
SN_(gamma gamma) are sufficient to chemically enrich a cubic megaparsec of the
intergalactic medium at high redshift for a variety of initial mass functions.
The number of ionizing photons provided by these SN_(gamma gamma) and also by
the pop III stars ending as black holes was computed and we conclude that there
are not enough photons to reionize the universe, being down by at least a
factor of ~ 3. Finally, we calculate the abundance ratios generated by pop III
stars and compare it with the ones observed in low metallicity Damped
Lyman-alpha systems (DLAs). We suggest that pop III stars alone cannot be
responsible for the abundance ratios in these objects and that intermediate
mass pop II stars must have played an important role especially in enriching
DLAs in nitrogen.


title: The peak luminosity - peak energy correlation in GRBs

abstract:
  We derive the peak luminosity - peak energy (L_iso - E_peak) correlation
using 22 long Gamma-Ray Bursts (GRBs) with firm redshift measurements. We find
that its slope is similar to the correlation between the time integrated
isotropic emitted energy E_iso and E_peak (Amati et al. 2002). For the 15 GRBs
in our sample with estimated jet opening angle we compute the collimation
corrected peak luminosity L_gamma, and find that it correlates with E_peak.
This has, however, a scatter larger than the correlation between E_peak and
E_gamma (the time integrated emitted energy, corrected for collimation;
Ghirlanda et al. 2004), which we ascribe to the fact that the opening angle is
estimated through the global energetics. We have then selected a large sample
of 442 GRBs with pseudo--redshifts, derived through the lag-luminosity
relation, to test the existence of the L_iso-E_peak correlation. With this
sample we also explore the possibility of a correlation between time resolved
quantities, namely L_iso,p and the peak energy at the peak of emission
E_peak,p.


title:
Proper Motions as an Underutilized Tool for Estimating Distances and
  Ages for Nearby, Young Stars

abstract:
  The recent availability of accurate proper motion catalogs for millions of
stars on the sky (e.g. Tycho-2, UCAC) can benefit projects for which age
estimates are needed for stars that are plausibly young (<100 Myr-old) and
within a few hundred pc of the Sun. Here I summarize how accurate proper
motions have been useful in (1) identifying new, nearby, post-T Tauri star
populations, and (2) estimating distances to young field stars which are
lacking trigonometric parallax measurements. The later enables the calculation
of stellar luminosities and isochronal ages -- two quantities critical for
investigations of the evolution of star/planet/disk systems.


title: GALICS -- VI. Modelling Hierarchical Galaxy Formation in Clusters

abstract:
  High-resolution N-body re-simulations of 15 massive (10^{14}-10^{15} Msun)
dark matter haloes have been combined with the hybrid galaxy formation model
GalICS (Hatton et al. 2003), to study the formation and evolution of galaxies
in clusters, within the framework of the hierarchical merging scenario. New
features in GalICS include a better description of galaxy positioning within
dark matter haloes, a more reliable computation of the temperature of the
inter-galactic medium as a function of redshift, and a description of the ram
pressure stripping process. We focus on the luminosity functions, morphological
fractions and colour distributions of galaxies in clusters and in cluster
outskirts, at z=0. No systematic dependency on cluster richness is found either
for the galaxy luminosity functions, morphological mixes, or colour
distributions. Moving from higher density (cluster cores), to lower density
environments (cluster outskirts), we detect a progressive flattening of the
luminosity functions, an increase of the fraction of spirals and a decrease of
that of ellipticals and S0s, and the progressive emergence of a bluer tail in
the distributions of galaxy colours, especially for spirals. As compared to
cluster spirals, early-type galaxies show a flatter luminosity function, and
more homogeneous and redder colours. An overall good agreement is found between
our results and the observations, particularly in terms of the cluster
luminosity functions and morphological mixes. However, some discrepancies are
also apparent, with too faint magnitudes of the brightest cluster members,
especially in the B band, and galaxy colours tendentially too red (or not blue
enough) in the model, with respect to the observations. Finally, ram pressure
stripping appears to affect very little our results.


title: The CIDA-UCM-Yale Shallow Survey for Emission Line Galaxies

abstract:
  We present the CIDA-UCM-Yale (Centro de Investigaciones de Astronomia,
Universidad Complutense de Madrid and Yale University) survey for
Halpha+[NII]6549,6584 emission-line galaxies using objective-prism spectra. The
most important properties of a catalogue with 427 entries and significant
subsets are analysed. The complete sample contains 183 statistically confirmed
ELGs in a sky area of 151 sq.deg. and redshift up to 0.14. We determine the
parameters of the Halpha luminosity function using the Halpha+[NII] flux
directly measured on the ELGs spectra in this sample and the star formation
rate density derived is in agreement with the values reported in the
literature. Finally, we study the clustering properties of local star-forming
galaxies relative to quiescent ones from different perspectives. We find that
emission-line galaxies avoid dense regions of quiescent galaxies and we propose
a power-law expression to parametrise the relation between star formation rate
density and environment volume density of emission-line galaxies.


abstract:
  The Fan Observatory Bench Optical Spectrograph (FOBOS) is intended for
single-object optical spectroscopy at moderate resolution (R~1500-3000) using a
fiber-fed, bench-mounted design to maintain stability. Whenever possible, the
instrument uses off-the-shelf components to maintain a modest cost. FOBOS
supports Galactic astronomy projects that require consistently well-measured
(~5 km/sec) radial velocities for large numbers of broadly distributed and
relatively bright (V<14) stars. The spectrograph provides wavelength coverage
throughout the optical spectrum, although the instrument design was optimized
for use in the range 470-670 nm. Test data indicate that the instrument is
stable and capable of measuring radial velocities with precision better than 3
km/sec at a resolution of R~1500 with minimal calibration overhead.


title:
The Low End of the Supermassive Black Hole Mass Function: Constraining
  the Mass of a Nuclear Black Hole in NGC 205 via Stellar Kinematics

abstract:
  Hubble Space Telescope (HST) images and spectra of the nucleated dwarf
elliptical galaxy NGC 205 are combined with 3-integral axisymmetric dynamical
models to constrain the mass (M_BH) of a putative nuclear black hole. This is
only the second attempt, after M33, to use resolved stellar kinematics to
search for a nuclear black hole with mass below 10^6 solar masses. We are
unable to identify a best-fit value of M_BH in NGC 205; however, the data
impose a upper limit of 2.2x10^4 M_sun (1sigma confidence) and and upper limit
of 3.8x10^4 M_sun (3sigma confidence). This upper limit is consistent with the
extrapolation of the M_BH-sigma relation to the M_BH < 10^6 M_sunregime. If we
assume that NGC 205 and M33 both contain nuclear black holes, the upper limits
on M_BH in the two galaxies imply a slope of ~5.5 or greater for the M_BH-sigma
relation. We use our 3-integral models to evaluate the relaxation time (T_r)
and stellar collision time (T_coll) in NGC 205; T_r~10^8 yr or less in the
nucleus and T_coll~10^11 yr. The low value of T_r is consistent with core
collapse having already occurred, but we are unable to draw conclusions from
nuclear morphology about the presence or absence of a massive black hole.


title: HETE-2 Observation of two gamma-ray bursts at z > 3

abstract:
  GRB 020124 and GRB 030323 constitute half the sample of gamma-ray bursts with
a measured redshift greater than 3. This paper presents the temporal and
spectral properties of these two gamma-ray bursts detected and localized with
HETE-2. While they have nearly identical redshifts (z=3.20 for GRB 020124, and
z=3.37 for GRB 030323), these two GRBs span about an order of magnitude in
fluence, thus sampling distinct regions of the GRB luminosity function. The
properties of these two bursts are compared with those of the bulk of the GRB
population detected by HETE-2. We also discuss the energetics of GRB 020124 and
GRB 030323 and show that they are compatible with the Epeak - Eiso relation
discovered by Amati et al. (2002). Finally, we compute the maximum redshifts at
which these bursts could have been detected by HETE-2 and we address various
issues connected with the detection and localization of high-z GRBs.


title:
Dissipationless Mergers of Elliptical Galaxies and the Evolution of the
  Fundamental Plane

abstract:
  We carry out numerical simulations of dissipationless major mergers of
elliptical galaxies using initial galaxy models that consist of a dark matter
halo and a stellar bulge with properties consistent with the observed
fundamental plane. By varying the density profile of the dark matter halo
(standard NFW versus adiabatically contracted NFW), the global stellar to dark
matter mass ratio, and the orbit of the merging galaxies, we are able to assess
the impact of each of these factors on the structure of the merger remnant. Our
results indicate that the properties of the remnant bulge depend primarily on
the angular momentum and energy of the orbit; for a cosmologically motivated
orbit, the effective radius and velocity dispersion of the remnant bulge remain
approximately on the fundamental plane. This indicates that the observed
properties of elliptical galaxies are consistent with significant growth via
late dissipationless mergers. We also find that the dark matter fraction within
the effective radius of our remnants increases after the merger, consistent
with the hypothesis that the tilt of the fundamental plane from the virial
theorem is due to a varying dark matter fraction as a function of galaxy mass.


title: The Anisotropic Distribution of Galactic Satellites

abstract:
  We present a study of the spatial distribution of subhalos in galactic dark
matter halos using dissipationless cosmological simulations of the concordance
LCDM model. We find that subhalos are distributed anisotropically and are
preferentially located along the major axes of the triaxial mass distributions
of their hosts. The Kolmogorov-Smirnov probability for drawing our simulated
subhalo sample from an isotropic distribution is P_KS \simeq 1.5 \times
10^{-4}. An isotropic distribution of subhalos is thus not the correct null
hypothesis for testing the CDM paradigm. The nearly planar distribution of
observed Milky Way (MW) satellites is marginally consistent (probability \simeq
0.02) with being drawn randomly from the subhalo distribution in our
simulations. Furthermore, if we select the subhalos likely to be luminous, we
find a distribution that is consistent with the observed MW satellites. In
fact, we show that subsamples of the subhalo population with a
centrally-concentrated radial distribution, similar to that of the MW dwarfs,
typically exhibit a comparable degree of planarity. We explore the origin of
the observed subhalo anisotropy and conclude that it is likely due to (1)
preferential accretion of subhalos along filaments, often closely aligned with
the major axis of the host halo, and (2) evolution of satellite orbits within
the prolate, triaxial potentials typical of CDM halos. Agreement between
predictions and observations requires the major axis of the outer dark matter
halo of the Milky Way to be nearly perpendicular to the disk. We discuss
possible observational tests of such disk-halo alignment with current large
galaxy surveys.


title:
The Angular Momentum Content and Evolution of Class I and Flat-Spectrum
  Protostars

abstract:
  We report on the angular momentum content of heavily embedded protostars
based on our analysis of the projected rotation velocities (v sin i s) of 38
Class I/flat spectrum young stellar objects presented by Doppmann et al (2005).
After correcting for projection effects, we find that infrared-selected Class
I/flat spectrum objects rotate significantly more quickly (median equatorial
rotation velocity ~ 38 km/sec) than Classical T Tauri stars (CTTSs; median
equatorial rotation velocity ~ 18 km/sec) in the Rho Ophiuchi and
Taurus-Aurigae regions. The detected difference in rotation speeds between
Class I/flat spectrum sources and CTTSs proves difficult to explain without
some mechanism which transfers angular momentum out of the protostar between
the two phases. Assuming Class I/flat spectrum sources possess physical
characteristics (M_*,R_*,B_*) typical of pre-main sequence stars, fully disk
locked Class I objects should have co-rotation radii within their protostellar
disks that match well (within 30%) with the predicted magnetic coupling radii
of Shu et al (1994). The factor of two difference in rotation rates between
Class I/flat spectrum and CTTS sources, when interpreted in the context of disk
locking models, also imply a factor of 5 or greater difference in mass
accretion rates between the two phases.


title: XTE J1550-564: INTEGRAL Observations of a Failed Outburst

abstract:
  The well known black-hole X-ray binary transient XTE J1550-564 underwent an
outburst during the spring of 2003 which was substantially underluminous in
comparison to previous periods of peak activity in that source. In addition,
our analysis shows that it apparently remained in the hard spectral state over
the duration of that outburst. This is again in sharp contrast to major
outbursts of that source in 1998/1999 during which it exhibited an irregular
light curve, multiple state changes and collimated outflows. This leads us to
classify it as a "failed outburst." We present the results of our study of the
spring 2003 event including light curves based on observations from both
INTEGRAL and RXTE. In addition, we studied the evolution of the high-energy
3-300 keV continuum spectrum using data obtained with three main instruments on
INTEGRAL. These spectra are consistent with typical low-hard-state thermal
Comptonization emission. We also consider the 2003 event in the context of a
multi-source, multi-event period-peak luminosity diagram in which it is a clear
outlyer. We then consider the possibility that the 2003 event was due to a
discrete accretion event rather than a limit-cycle instablility. In that
context, we apply model fitting to derive the timescale for viscous propagation
in the disk, and infer some physical characteristics.


title:
Evolution of accretion disks around massive black holes: constraints
  from the demography of active galactic nuclei

abstract:
  Observations have shown that the Eddington ratios (the ratio of the
bolometric luminosity to the Eddington luminosity) in QSOs/active galactic
nuclei (AGNs) cover a wide range. In this paper we connect the demography of
AGNs obtained by the Sloan Digital Sky Survey with the accretion physics around
massive black holes and propose that the diversity in the Eddington ratios is a
natural result of the long-term evolution of accretion disks in AGNs. The
observed accretion rate distribution of AGNs (with host galaxy velocity
dispersion sigma~70-200 km/s) in the nearby universe (z<0.3) is consistent with
the predictions of simple theoretical models in which the accretion rates
evolve in a self-similar way. We also discuss the implications of the results
for the issues related to self-gravitating disks, coevolution of galaxies and
QSOs/AGNs, and the unification picture of AGNs.


title: Can LISA Resolve Distance to the Large Magellanic Cloud?

abstract:
  The Laser Interferometer Space Antenna (LISA) is expected to detect N ~ 22
[x10^(+/- 1)] close white dwarf binaries in the Large Magellanic Cloud (LMC)
through their gravitational radiation with signal-to-noise ratios greater than
10 in observational durations of 3 years or more. In addition to chirp mass,
location on the sky, and other binary parameters, the distance to each binary
is an independent parameter that can be extracted from an analysis of
gravitational waves from these binaries. Using a sample of binaries, one can
establish the mean distance to the LMC as well as the variance of this
distance. Assuming no confusion noise at frequencies above 2 mHz, LISA might
determine the LMC distance to ~ 4.5 (N/22)^(1/2)% and the line of sight extent
of LMC to ~ 15 (N/22)^(1/4)$%, relative to its distance, at the one-sigma
confidence. These estimates are competitive to some of the proposed direct
geometric techniques to measure LMC distance in future with missions such as
SIM and GAIA.


title:
Polarimetric Observations of 15 Active Galactic Nuclei at High
  Frequencies: Jet Kinematics from Bimonthly Monitoring with the Very Long
  Baseline Array

abstract:
  We present total and polarized intensity images of 15 active galactic nuclei
obtained with the Very Long Baseline Array at 7 mm at 17 epochs from 1998 March
to 2001 April. At some epochs the images are accompanied by nearly simultaneous
polarization measurements at 3 mm, 1.35/0.85 mm, and optical wavelengths. Here
we analyze the 7 mm images to define the properties of the jets of two radio
galaxies, five BL Lac objects, and eight quasars on angular scales $\gtrsim
0.1$ milliarcseconds. We determine the apparent velocities of 106 features in
the jets; for many of the features we derive Doppler factors using a new method
based on comparison of timescale of decline in flux density with the
light-travel time across the emitting region. This allows us to estimate the
Lorentz factors, intrinsic brightness temperatures, and viewing angles of 73
superluminal knots, as well as the opening angle of the jet for each source. We
analyze the derived physical parameters of the jets. In nine sources we detect
statistically meaningful deviations from ballistic motion, with the majority of
components accelerating with distance from the core. In six sources we identify
jet features with characteristics of trailing shocks that form behind the
primary strong perturbations in jet simulations. The apparent speeds of these
components increase with distance from the core suggesting an acceleration of
the underlying jet.


title: Light curves of oscillating neutron stars

abstract:
  We calculate light curves produced by $r$-modes with small azimuthal
wavenumbers, $m$, propagating in the surface fluid ocean of rotating neutron
stars. We include relativistic effects due to rapid rotation, and propagate
photons from the stellar surface to a distant observer using the Schwarzschild
metric. The wave motions of the surface $r$-modes are confined to the
equatorial region of the star, and the surface pattern of the temperature
variation can be either symmetric (for even modes) or anti-symmetric (for odd
modes) with respect to the equator. Since for the surface $r$-modes the
oscillation frequency in the corotating frame of the star is much smaller than
the rotation frequency, $\Omega$, we employ the approximation in which the
oscillation frequency in the inertial frame, $\sigma$, is given by $\sigma=
-m\Omega$. We find that the $even$, $m = 1$ $r$-mode produces the largest light
variations. The dominant Fourier component in the light curves of these modes
is the fundamental having $\sigma=-\Omega$, and the first harmonic component
having $\sigma=-2\Omega$ is always negligible in comparison. The dominant
Fourier component of the even, $m=2$ $r$-modes is the first harmonic. Although
the $odd$ $r$-modes produce smaller amplitude light variations compared with
the $even$ modes, the light curves of the former have a stronger first harmonic
component. If both $m=1$ and 2 $r$-modes are excited simultaneously, a rich
variety of light curves is possible, including those having an appreciable
first harmonic component. We show that the phase difference, $\delta-\delta_E$,
between the bolometric light curve and that at a particular photon energy can
possibly be used as a probe of the stellar compactness, $R/M$, where $R$ and
$M$ are the radius and mass of the star.


title: Orbital modulation of emission of the binary pulsar J0737-3039B

abstract:
  In binary radio pulsar system J0737-3039, slow pulsar B shows orbital
modulations of intensity, being especially bright at two short orbital phases.
We propose that these modulations are due to distortion of pulsar B
magnetosphere by pulsar A wind which produces orbital phase-dependent changes
of the direction along which radio waves are emitted. In our model, pulsar B is
intrinsically bright at all times but its radiation beam misses the Earth at
most orbital phases. We employ a simple model of distorted B magnetosphere
using stretching transformations of Euler potentials of dipolar fields. To fit
observations we use parameters of pulsar B derived from modeling of A eclipses
(Lyutikov and Thompson 2005). The model reproduces two bright regions
approximately at the observed orbital phases, explains variations of the pulse
shape between them and regular timing residuals within each emission window. It
also makes predictions for timing properties and secular variations of pulsar B
profiles.


title:
[O I] 6300A emission in Herbig Ae/Be systems: signature of Keplerian
  rotation

abstract:
  We present high spectral-resolution optical spectra of 49 Herbig Ae/Be stars
in a search for the [O I] 6300A line. The vast majority of the stars in our
sample show narrow (FWHM < 100 km/s) emission lines, centered on the stellar
radial velocity. In only three sources is the feature much broader (~400 km/s),
and strongly blueshifted (-200 km/s) compared to the stellar radial velocity.
Some stars in our sample show double-peaked lines profiles, with peak-to-peak
separations of ~10 km/s. The presence and strength of the [O I] line emission
appears to be correlated with the far-infrared energy distribution of each
source: stars with a strong excess at 60 micron have in general stronger [O I]
emission than stars with weaker 60 micron excesses. We interpret these narrow
[O I] 6300A line profiles as arising in the surface layers of the
protoplanetary disks surrounding Herbig Ae/Be stars. A simple model for [O I]
6300A line emission due to the photodissociation of OH molecules shows that our
results are in quantitative agreement with that expected from the emission of a
flared disk if the fractional OH abundance is ~5 x 10^{-7}.


title:
Early GRB Optical and Infrared Afterglow Observations with the 2-m
  Robotic Liverpool Telescope

abstract:
  We present the first optical observations of a Gamma Ray Burst (GRB)
afterglow using the 2-m robotic Liverpool Telescope (LT), which is owned and
operated by Liverpool John Moores University and situated on La Palma. We
briefly discuss the capabilities of LT and its suitability for rapid follow-up
observations of early optical and infrared GRB light curves. In particular, the
combination of aperture, site, instrumentation and rapid response (robotic
over-ride mode aided by telescope's rapid slew and fully-opening enclosure)
makes the LT ideal for investigating the nature of short bursts, optically-dark
bursts, and GRB blast-wave physics in general. We briefly describe the LT's key
position in the RoboNet-1.0 network of robotic telescopes. We present the LT
observations of GRB041006 and use its gamma-ray properties to predict the time
of the break in optical light curve, a prediction consistent with the
observations.


title:
The Liverpool Telescope Automatic Pipeline for Real-time GRB Afterglow
  Detection

abstract:
  The 2-m robotic Liverpool Telescope (LT) is ideally suited to the rapid
follow-up of unpredictable and transient events such as GRBs. Our GRB follow-up
strategy is designed to identify optical/IR counterparts in real time; it
involves the automatic triggering of initial observations, on receipt of an
alert from Gamma Ray Observatories HETE-2, INTEGRAL and Swift, followed by
automated data reduction, analysis, OT identification and subsequent observing
mode choice. The lack of human intervention in this process requires robustness
at all stages of the procedure. Here we describe the telescope, its
instrumentation and GRB pipeline.


title:
Effects of black hole's gravitational field on the luminosity of a star
  during close encounter

abstract:
  To complement hydrodynamic studies of the tidal disruption of the star by a
massive black hole, we present the study of stellar luminosity and its
variations, produced by the strong gravitational field of the black hole during
a close encounter. By simulating the relativistically moving star and its
emitted light and taking into account general relativistic effects on particle
and light trajectories, our results show that the black hole's gravity alone
induces apparent stellar luminosity variations on typical timescales of a few
r_g/c (=5 sec m_bh/10^6 M_\odot) to a few 100 r_g/c (\sim 10 min m_bh/10^6
M_\odot), where r_g=Gm_bh/c^2. We discern different cases with respect to the
strength of tidal interaction and focus on two: a) a star encountering a giant
black hole traces space-time almost as a point particle, so that the apparent
luminosity variations are dominated by clearly recognizable general
relativistic effects and b) in a close encounter of a star with a black hole of
similar size the stellar debris is spread about the black hole by processes
where hydrodynamics plays an important role. We discuss limitations and results
of our approach.


title:
Berkeley 22, an old and distant open cluster towards the Galactic
  anticentre

abstract:
  We present deep CCD BVI photometry of the distant, old open cluster Berkeley
22, covering from the red giants branch (RGB) to about 6 magnitudes below the
main sequence (MS) turn-off. Using the synthetic Colour - Magnitude Diagram
method with three different types of stellar evolutionary tracks, we estimate
values and theoretical uncertainty of distance modulus mod0, reddening E(B-V),
age tau and approximate metallicity. The best fit to the data is obtained for
13.8 <= mod0 <= 14.1, 0.64 <= E(B-V) <= 0.65, 2 <= tau <= 2.5 Gyr (depending on
the amount of overshooting from convective regions adopted in the stellar
models) and solar metallicity.


title: On MHD jet production in the collapsing and rotating envelope

abstract:
  We present results from axisymmetric, time-dependent hydrodynamical (HD) and
magnetohydrodynamical (MHD) simulations of a gaseous envelope collapsing onto a
black hole (BH). We consider gas with so small angular momentum that after an
initial transient, the flow in the HD case, accretes directly onto a BH without
forming a rotationally support torus. However, in the MHD case even with a very
weak initial magnetic field, the flow settles into a configuration with four
components: (i) an equatorial inflow, (ii) a bipolar outflow, (iii) polar
funnel outflow, and (iv) polar funnel inflow. We focus our analysis on the
second flow component of the MHD flow which represents a simple yet robust
example of a well-organized inflow/outflow solution to the problem of MHD jet
formation. The jet is heavy, highly magnetized, and driven by magnetic and
centrifugal forces. A significant fraction of the total energy in the jet is
carried out by a large scale magnetic field. We review previous simulations,
where specific angular momentum was higher than that assumed here, and conclude
that our bipolar outflow develops for a wide range of the properties of the
flow near the equator and near the poles. Future work on such a simple
inflow/outflow solution will help to pinpoint the key elements of real
jets/outflows as well as help to interpret much more complex simulations aimed
at studying jet formation and collapse of magnetized envelopes.


title:
A near-infrared and optical photometric study of the Sculptor dwarf
  spheroidal galaxy: implications for the metallicity spread

abstract:
  We present here a detailed study of the Sculptor dSph galaxy red giant branch
(RGB) and horizontal branch (HB) morphology, combining new near-infrared
photometry from CIRSI, with optical data from the ESO WFI. For a Sculptor-like
old and generally metal-poor system, the position of RGB stars on the
colour-magnitude diagram is mainly metallicity dependent. The advantage of
using optical-NIR colours is that the position of the RGB locus is much more
sensitive to metallicity than with optical colours alone. In contrast the
horizontal branch (HB) morphology is strongly dependent on both metallicity and
age. Therefore a detailed study of both the RGB in optical-NIR colours and the
HB can help break the age-metallicity degeneracy. Our measured photometric
width of the Sculptor giant branch corresponds to a range in metallicity of
0.75 dex. We detect the RGB and AGB bumps in both the NIR and optical
luminosity functions, and derive from them a mean metallicity of [M/H] = -1.3
+/- 0.1. From isochrone fitting we derive a mean metallicity of [Fe/H] = -1.42
with a dispersion of 0.2 dex. These photometric estimators are for the first
time consistent with individual metallicity measurements derived from
spectroscopic observations. No spatial gradient is detected in the RGB
morphology within a radius of 13 arcmin, twice the core radius. On the other
hand, a significant gradient is observed in the HB morphology index, confirming
the `second parameter problem' present in this galaxy. These observations are
consistent with an early extended period of star formation continuing in time
for a few Gyr. (Abridged)


title: The population of black widow pulsars

abstract:
  We consider the population of black widow pulsars (BWPs). The large majority
of these are members of globular clusters. For minimum companion masses < 0.1
Msun, adiabatic evolution and consequent mass loss under gravitational
radiation appear to provide a coherent explanation of all observable
properties. We suggest that the group of BWPs with minimum companion masses >
0.1 Msun are systems relaxing to equilibrium after a relatively recent capture
event. We point out that all binary millisecond pulsars (MSPs) with orbital
periods P < 10 h are BWPs (our line of sight allows us to see the eclipses in
10 out of 16 cases). This implies that recycled MSPs emit either in a wide fan
beam or a pencil beam close to the spin plane. Simple evolutionary ideas favour
a fan beam.


title: Long-term variations in the pulse emission from PSR J0737-3039B

abstract:
  Analysis of 20 months of observations at the Parkes radio telescope shows
secular changes in the pulsed emission from J0737-3039B, the 2.77 s pulsar of
the double-pulsar system. Pulse profiles are becoming single-peaked in both
bright phases of the orbital modulation although there is no clear variation in
overall pulse width. The shape of the orbital modulation is also varying
systematically, with both bright phases shrinking in longitude by ~ 7 deg/yr.
However, the combined span of the two bright phases is relatively constant and
together they are shifting to higher longitudes at a rate of ~ 3 deg/yr. We
discuss the possible contributions of geodetic precession and periastron
advance to the observed variations.


title: Cosmological mass functions and moving barrier models

abstract:
  In the ellipsoidal collapse model, the critical density for the collapse of a
gravitationally bound object is a function of its mass. In the excursion set
formalism, this translates into a moving barrier problem such that the mass
function of dark matter haloes is given by the first crossing probability of a
random walker across the barrier. In this paper, we study this first crossing
probability analytically. Complete solutions are obtained for barriers that
vary as square root of time and square of time. Large and small time asymptotic
behaviour is derived. For arbitrary power-law barriers, the large time
behaviour is determined. The solutions allow us to derive useful inferences
about the scaling of the conditional mass function in terms of present day halo
masses and look back redshifts. As an application of our results, we compare
the estimates of major merger rates of haloes in constant and moving barrier
models and find that for massive haloes ($10^{12-13} M_\odot$) the latter
predicts significantly higher merger rates towards high redshifts ($z \gtrsim
4$)


title:
Multiple sources or late injection of short-lived r-nuclides in the
  early solar system?

abstract:
  Comparisons between the predicted abundances of short-lived r-nuclides
(107Pd, 129I, 182Hf, and 244Pu) in the interstellar medium (ISM) and the
observed abundances in the early solar system (ESS) conclusively showed that
these nuclides cannot simply be derived from galactic chemical evolution (GCE)
if synthesized in a unique stellar environment. It was thus suggested that two
di erent types of stars were responsible for the production of light and heavy
r-nuclides. Here, new constraints on the 244Pu=238U production ratio are used
in an open nonlinear GCE model. It is shown that the two r-process scenario
cannot explain the low abundance of 244Pu in the ESS and that this requires
either than actinides be produced at an additional site (A-events) or more
likely, that 129I and 244Pu be inherited from GCE and 107Pd and 182Hf be
injected in the ESS by the explosion of a nearby supernova.


title: A Universal Density Profile for Dark and Luminous Matter?

abstract:
  We explore similarities in the luminosity distribution of early type galaxies
and the mass profiles of LCDM halos. The spatial structure of these systems may
be accurately described by a simple law where the logarithmic slope of the
projected density is a power law of radius; the Sersic law. We show that this
law provides a significantly better fit than a three-parameter generalization
of the NFW profile and derive the best-fitting Sersic parameters for a set of
high-resolution LCDM halos spanning a wide range in mass. The mean Sersic n
values are 3.0 for dwarf- and galaxy-sized halos and 2.4 for cluster-sized
halos, similar to the values that characterize luminous elliptical galaxies. We
discuss possible reasons why the same law should describe dark and luminous
systems that span a range of over seven decades in mass.


title:
Far-Infrared and Millimeter Continuum Studies of K Giants: Alpha Boo and
  Alpha Tau

abstract:
  We have imaged two normal, non-coronal, infrared-bright K giants, Alpha Tau
and Alpha Boo, in the 1.4-mm and 2.8-mm continuum using the Berkeley Illinois
Maryland Association millimeter array. These stars have been used as important
absolute calibrators for several infrared infrared satellites. Our goals are:
(1) to establish whether these stars radiate as simple photospheres or possess
long-wavelength chromospheres; and (2) to make a connection between millimeter
wave and far-infrared absolute flux calibrations. To accomplish these goals we
also present Infrared Space Observatory Long Wavelength Spectrometer
measurements of both these K giants. The far-infrared and millimeter continuum
radiation is produced in the vicinity of the temperature minimum in Alpha Tau
and Alpha Boo. We find that current photospheric models predict fluxes in
reasonable agreement with those observed for wavelengths which sample the upper
photosphere, namely <=125 microns in Alpha Tau and Alpha Boo. We clearly detect
chromospheric radiation from both stars by 2.8mm (by 1.4mm in the case of Alpha
Boo). Only additional observations can determine precisely where beyond 125
microns the purely radiative models fail. Until then, purely radiative models
for these stars can only be used with confidence for calibration purposes below
125 microns.


title: The baryonic mass function of galaxies

abstract:
  In the Big Bang about 5% of the mass that was created was in the form of
normal baryonic matter (neutrons and protons). Of this about 10% ended up in
galaxies in the form of stars or of gas (that can be in molecules, can be
atomic, or can be ionised).
  In this work, we measure the baryonic mass function of galaxies, which
describes how the baryonic mass is distributed {\it within} galaxies of
different types (e.g. spiral or elliptical) and of different sizes. This can
provide useful constraints on our current cosmology, convolved with our
understanding of how galaxies form. This work relies on various large
astronomical surveys, for example the optical Sloan Digital Sky Survey (to
observe stars) and the HIPASS radio survey (to observe atomic gas). We then
perform an integral over our mass function to determine the cosmological
density in baryons in galaxies: $\Omega_{\rm b, gal} = 0.0035$. Most of these
baryons are in stars: $\Omega_{*} = 0.0028$. Only about 20% are in gas. The
error on the quantities, as determined from the range obtained between
different methods, is $\sim 10$%; systematic errors may be much larger.
  Most ($\sim 90$%) of the baryons in the Universe are not in galaxies. They
probably exist in a warm/hot intergalactic medium. Searching for direct
observational evidence and deeper theoretical understanding for this will form
one of the major challenges for astronomy in the next decade.


title: R-Modes on Rapidly Rotating, Relativistic Stars : II. Blackbody Emission

abstract:
  Rossby waves (or r-modes) on the surface of a neutron star have become a
leading model for the oscillations observed during the tail of Type-I X-ray
bursts. Their frequency evolution matches well with the observed frequency
drifts of the oscillations in the bursts, and the burning appears to excite
these waves quite naturally. This paper addresses the detailed shape of the
expected flux profiles from r-modes on neutron stars as a function of energy.
R-modes naturally account for both the small amplitude of the observed
oscillations and their lack of harmonic content. However, the model predicts
that the oscillation at higher energies leads the lower energy variation. The
observed oscillations have the opposite trend which possibly indicates that the
higher energy photons are upscattered in the plasma surrounding the neutron
star and therefore delayed.


title: Energetics in MRI driven Turbulence

abstract:
  In these proceedings we present recent efforts to understand the energetics
of magnetohydrodynamic (MHD) turbulence driven by the magneto-rotational
instability (MRI). These studies are carried out in the local (shearing box)
approximation using the Athena simulation code. Athena is a higher order
Godunov algorithm based on the piecewise parabolic method (PPM), the corner
transport upwind (CTU) integration algorithm, and the constrained transport
(CT) algorithm for evolving the magnetic field. This algorithm is particularly
suited for these studies owing to the conservation properties of a Godunov
scheme and the particular implementation of the shearing box source terms used
here. We present a variety of calculations which may be compared directly to
previously published results and discuss them in some detail. The only
significant discrepancy found between the results presented here and in the
published literature involves the turbulent heating rate. We observe the
presence of recurrent channel solutions in calculations involving a mean
vertical magnetic field and the associated time lag between the energy
injection and thermalization rate. We also present the results of a shearing
box calculation which includes an optically thin radiative term with a cooling
rate selected to match the turbulent heating rate. Some properties which we
find uniformly present in all of the calculations presented here are
compressible fluctuations, spiral waves and weak shocks. It is found that these
compressible modes dominate the temporal fluctuations in the probability
distribution functions for most of the thermodynamic variables; only the
specific entropy is relatively immune to their effects.


title: Eleven New DAVs from the Sloan Survey

abstract:
  We report the discovery of eleven new variable DA white dwarf (ZZ Ceti)
stars. Candidates were selected by deriving temperatures from model fits to
spectra obtained from the Sloan Digital Sky Survey. We also find objects whose
temperatures and gravities indicate they lie within the instability strip for
pulsation, but which were not observed to vary. Although the temperatures are
based on relatively low S/N spectra, an impure strip is unexpected, and if
confirmed suggests that our knowledge of the pulsation mechanism is incomplete.
This work brings the total number of published variable DA white dwarf stars to
82.


title: Revealing the Supernova--Gamma-Ray Burst Connection with TeV Neutrinos

abstract:
  Gamma-ray bursts (GRBs) are rare but powerful explosions displaying highly
relativistic jets. It has been suggested that a significant fraction of the
much more frequent core-collapse supernovae are accompanied by comparably
energetic but mildly relativistic jets, which would indicate an underlying
supernova--GRB connection. We calculate the neutrino spectra from the decays of
pions and kaons produced in jets in supernovae, and show that the kaon
contribution is dominant and provides a sharp break near 20 TeV, which is a
sensitive probe of the conditions inside the jet. For a supernova at 10 Mpc, 30
events above 100 GeV are expected in a 10 s burst in the IceCube detector.


title: The polarized electron target as a new solar-neutrino detector

abstract:
  In this paper, we analyze the scattering of solar neutrinos on the polarized
electron target, and predict how the effect of parity violation in weak
interactions may help to distinguish neutrino signal from detector background.
We indicate that the knowledge of the Sun motion across the sky is sufficient
to predict the day/night asymmetry in the $(\nu_ee^-)$ scattering on the
polarized electron target. To make this detection feasible, the polarized
electron target for solar neutrinos needs to be build from magnetic materials,
e.g. from ferromagnetic iron foils, paramagnetic scintillator crystals or
scintillating ferrofluids.


title: FUSE Measurements of Far Ultraviolet Extinction. I. Galactic Sight Lines

abstract:
  We present extinction curves that include data down to far ultraviolet
wavelengths (FUV; 1050 - 1200 A) for nine Galactic sight lines. The FUV
extinction was measured using data from the Far Ultraviolet Spectroscopic
Explorer. The sight lines were chosen for their unusual extinction properties
in the infrared through the ultraviolet; that they probe a wide range of dust
environments is evidenced by the large spread in their measured ratios of
total-to-selective extinction, R_V = 2.43 - 3.81. We find that extrapolation of
the Fitzpatrick & Massa relationship from the ultraviolet appears to be a good
predictor of the FUV extinction behavior. We find that predictions of the FUV
extinction based upon the Cardelli, Clayton & Mathis (CCM) dependence on R_V
give mixed results. For the seven extinction curves well represented by CCM in
the infrared through ultraviolet, the FUV extinction is well predicted in three
sight lines, over-predicted in two sight lines, and under-predicted in 2 sight
lines. A Maximum Entropy Method analysis using a simple three component grain
model shows that seven of the nine sight lines in the study require a larger
fraction of grain materials to be in dust when FUV extinction is included in
the models. Most of the added grain material is in the form of small (radii <
200 A) grains.


title:
Further evidence for the presence of a neutron star in 4U 2206+54.
  INTEGRAL and VLA observations

abstract:
  The majority of High Mass X-ray Binaries (HMXBs) behave as X-ray pulsars,
revealing that they contain a magnetised neutron star. Among the four HMXBs not
showing pulsations, and that do not show the characteristics of accreting black
holes, there is the unusual HMXB 4U 2206+54. Here we present contemporaneous
high-energy and radio observations of this system conducted with INTEGRAL and
the VLA in order to unveil its nature. The high-energy spectra show clear
indications of the presence of an absorption feature at ~32 keV. This is the
third high-energy observatory which reveals marginal evidence of this feature,
giving strong support to the existence of a cyclotron resonance scattering
feature, which implies a magnetic field of 3.6 x 10^12 G. On the other hand,
the source is not detected at centimetre radio wavelengths with a 3 sigma upper
limit of 0.039 mJy. The expected radio emission for an accreting black hole in
the low/hard state, inferred from X-ray flux measurements, would be at least 60
times greater than the measured upper limit. Both results firmly indicate that,
in spite of the absence of pulsations, 4U 2206+54 hosts a magnetic accreting
neutron star, the first one not to be observed as an X-ray pulsar.


title: The Variation of Integrated Star IMFs among Galaxies

abstract:
  The integrated galaxial initial mass function (IGIMF) is the relevant
distribution function containing the information on the distribution of stellar
remnants, the number of supernovae and the chemical enrichment history of a
galaxy. Since most stars form in embedded star clusters with different masses
the IGIMF becomes an integral of the assumed (universal or invariant) stellar
IMF over the embedded star-cluster mass function (ECMF). For a range of
reasonable assumptions about the IMF and the ECMF we find the IGIMF to be
steeper (containing fewer massive stars per star) than the stellar IMF, but
below a few Msol it is invariant and identical to the stellar IMF for all
galaxies. However, the steepening sensitively depends on the form of the ECMF
in the low-mass regime. Furthermore, observations indicate a relation between
the star formation rate of a galaxy and the most massive young stellar cluster
in it. The assumption that this cluster mass marks the upper end of a
young-cluster mass function leads to a connection of the star formation rate
and the slope of the IGIMF above a few Msol. The IGIMF varies with the star
formation history of a galaxy. Notably, large variations of the IGIMF are
evident for dE, dIrr and LSB galaxies with a small to modest stellar mass. We
find that for any galaxy the number of supernovae per star (NSNS) is suppressed
relative to that expected for a Salpeter IMF. Dwarf galaxies have a smaller
NSNS compared to massive galaxies. For dwarf galaxies the NSNS varies
substantially depending on the galaxy assembly history and the assumptions made
about the low-mass end of the ECMF. The findings presented here may be of some
consequence for the cosmological evolution of the number of supernovae per
low-mass star and the chemical enrichment of galaxies of different mass.


title:
The Hubble Deep Field North SCUBA Super-map III - Optical and
  near-infrared properties of submillimetre galaxies

abstract:
  We present a new sub-mm Super-map in the HDF-North region (GOODS-North
field), containing 40 statistically robust sources at 850 microns. This map
contains additional data, and several new sources, including one of the
brightest blank-sky extragalactic sub-mm sources ever detected. We have used
the ACS HST images and ground-based near-IR observations from GOODS to develop
a systematic approach for counterpart identification. 72 per cent of our
sources with optical coverage have a unique optical counterpart using our new
techniques for counterpart identification, and an additional 18 per cent have
more than one possibility that meet our criteria in the ACS images. We have
found a much higher ERO rate than other sub-mm surveys, due to the increased
depth in the optical images. The median photometric redshift (and quartile
range), from optical and near-infrared data, is 1.7 (1.3-2.5) for the
radio-detected sub-mm sources, and rises to 2.3 (1.3-2.7) for the
radio-undetected sub-sample. We find interesting correlations between the 850
micron flux and both the i magnitude and the photometric redshift, from which
there appears to be an absence of high redshift faint counterparts to the lower
flux density SCUBA sources. While the quantitative morphologies span a range of
values, in general the sub-mm galaxies show larger sizes and a higher degree of
asymmetry than other galaxy populations at the same redshifts.


title:
Spitzer Studies of Ultracool Subdwarfs: Metal-poor Late-type M, L and T
  Dwarfs

abstract:
  Recent discoveries from red optical proper motion and wide-field
near-infrared surveys have uncovered a new population of ultracool subdwarfs,
metal-poor stars and brown dwarfs extending into the late-type M, L and
possibly T spectral classes. These objects are among the first low-mass stars
and brown dwarfs formed in the Galaxy, and are valuable tracers of metallicity
effects in low-temperature atmospheres. Like solar metallicity late-type
dwarfs, ultracool subdwarfs emit the majority of their emergent flux at
infrared wavelengths. Here I discuss how Spitzer observations will contribute
to the study of these objects, enabling measurement of the temperature scale,
tests for dust formation and the identification of surface gravity and
metallicity diagnostics in the coldest brown dwarfs.


title:
A Systematic Search for Gravitationally-Lensed Arcs in the Hubble Space
  Telescope WFPC2 Archive

abstract:
  We present the results of a systematic search for gravitationally-lensed arcs
in clusters of galaxies located in the Hubble Space Telescope Wide Field and
Planetary Camera 2 data archive. By carefully examining the images of 128
clusters we have located 12 candidate radial arcs and 104 tangential arcs, each
of whose length to width ratio exceeds 7. In addition, 24 other radial arc
candidates were identified with a length to width ratio less than 7. Keck
spectroscopy of 17 candidate radial arcs suggests that contamination of the
radial arc sample from non-lensed objects is ~30-50%. With our catalog, we
explore the practicality of using the number ratio of radial to tangential arcs
as a statistical measure of the slope \beta of the dark matter distribution in
cluster cores (where \rho_{DM}\propto r^{-\beta} at small radii). Despite the
heterogeneous nature of the cluster sample, we demonstrate that this abundance
ratio is fairly constant across various cluster subsamples partitioned
according to X-ray luminosity and optical survey depth. We develop the
necessary formalism to interpret this ratio in the context of two-component
mass models for cluster cores. Although the arc statistics in our survey are
consistent with a range of density profiles -- \beta<~1.6 depending on various
assumptions, we show that one of the prime limiting factors is the distribution
of stellar masses for the brightest cluster galaxies. We discuss the prospects
for improving the observational constraints and thereby providing a reliable
statistical constraint on cluster dark matter profiles on <~100 kpc scales.


title:
Gravitational Radiation from Coalescing Supermassive Black Hole Binaries
  in a Hierarchical Galaxy Formation Model

abstract:
  We investigate the expected gravitational wave emission from coalescing
supermassive black hole (SMBH) binaries resulting from mergers of their host
galaxies. We employ a semi-analytic model of galaxy and quasar formation based
on the hierarchical clustering scenario to estimate the amplitude of the
expected stochastic gravitational wave background owing to inspiraling SMBH
binaries and bursts rates owing to the SMBH binary coalescence events. We find
that the characteristic strain amplitude of the background radiation is $h_c(f)
\sim 10^{-16} (f/1 \mu {\rm Hz})^{-2/3}$ for $f \lesssim 1 \mu {\rm Hz}$. The
main contribution to the total strain amplitude of the background radiation
comes from SMBH coalescence events at $0<z<1$. We also find that a future
space-based gravitational wave interferometer such as the planned \textit{Laser
Interferometer Space Antenna} ({\sl LISA}) might detect intense gravitational
wave bursts associated with coalescence of SMBH binaries with total mass
$M_{\rm tot} < 10^7 M_{\odot}$ at $z \gtrsim 2$ at a rate $ \sim 1.0 {\rm
yr}^{-1}$. Our model predicts that burst signals with a larger amplitude
$h_{\rm burst} \sim 10^{-15}$ correspond to coalescence events of massive SMBH
binary with total mass $M_{\rm tot} \sim 10^8 M_{\odot}$ at low redshift $ z
\lesssim 1$ at a rate $ \sim 0.1 {\rm yr}^{-1}$ whereas those with a smaller
amplitude $h_{\rm burst} \sim 10^{-17}$ correspond to coalescence events of
less massive SMBH binary with total mass $M_{\rm tot} \sim 10^6 M_{\odot}$ at
high redshift $ z \gtrsim 3$.


title: The M/L ratio of massive young clusters

abstract:
  We point out a strong time-evolution of the mass-to-light conversion factor
\eta commonly used to estimate masses of dense star clusters from observed
cluster radii and stellar velocity dispersions. We use a gas-dynamical model
coupled with the Cambridge stellar evolution tracks to compute line-of-sight
velocity dispersions and half-light radii weighted by the luminosity. Stars at
birth are assumed to follow the Salpeter mass function in the range [0.15--17
M_\sun]. We find that $\eta$, and hence the estimated cluster mass, increases
by factors as large as 3 over time-scales of 20 million years. Increasing the
upper mass limit to $50 M_\sun$ leads to a sharp rise of similar amplitude but
in as little as 10 million years.
  Fitting truncated isothermal (Michie-King) models to the projected light
profile leads to over-estimates of the concentration par ameter c of $\delta
c\approx 0.3$ compared to the same functional fit applied to the proj ected
mass density.


title: High-Velocity Features: a ubiquitous property of Type Ia SNe

abstract:
  Evidence of high-velocity features such as those seen in the near-maximum
spectra of some Type Ia Supernovae (eg SN 2000cx) has been searched for in the
available SNIa spectra observed earlier than one week before B maximum. Recent
observational efforts have doubled the number of SNeIa with very early spectra.
Remarkably, all SNeIa with early data (7 in our RTN sample and 10 from other
programmes) show signs of such features, to a greater or lesser degree, in CaII
IR, and some also in SiII 6255A line. High-velocity features may be interpreted
as abundance or density enhancements. Abundance enhancements would imply an
outer region dominated by Si and Ca. Density enhancements may result from the
sweeping up of circumstellar material by the highest velocity SN ejecta. In
this scenario, the high incidence of HVFs suggests that a thick disc and/or a
high-density companion wind surrounds the exploding white dwarf, as may be the
case in Single Degenerate systems. Large-scale angular fluctuations in the
radial density and abundance distribution may also be responsible: this could
originate in the explosion, and would suggest a deflagration as the more likely
explosion mechanism. CSM-interaction and surface fluctuations may coexist,
possibly leaving different signatures on the spectrum. In some SNe the HVFs are
narrowly confined in velocity, suggesting the ejection of blobs of burned
material.


title: HCN and HCO+ Observations of the Galactic Circumnuclear Disk

abstract:
  We present high spatial resolution (5.1" x 2.7") OVRO millimeter array
observations of HCN (J=1-0) and HCO+ (J=1-0) emission in the inner 3 pc of the
galaxy. The HCN and HCO+ emission of the circumnuclear disk (CND) is
distributed in a well-defined ring with a peak at a radius of 1.6pc. The
HCO+/HCN emission ratio is typically ~0.4 but with significant variations. The
HCN emission is well correlated with the H_2 emission at 2.12 microns both in
the main emission lobes of the CND and also in four filaments. Multiple areas
of interaction between the ionized gas and the CND are also seen - the western
arm of the minispiral is spatially and kinematically consistent with being the
ionized inner edge of the CND, and the northern arm may be connected to the CND
northeastern extension. With the enhanced spatial resolution of the HCN map, we
resolve numerous dense molecular gas cores within the CND with characteristic
diameter of 7" (0.25pc). For 26 of the more isolated cores, we measure sizes,
velocity widths, and integrated fluxes. We estimate three masses for each core:
a virial mass, an optically thick mass, and a lower limit mass assuming
optically thin HCN emission. The virial and optically thick masses are in good
agreement with a typical mass of (2-3)x10^4 M_sun and a total CND gas mass of
10^6 M_sun. The internal densities implied by these core masses are on average
(3-4)x10^7 cm^-3, high enough to be stable against tidal disruption from Sgr A*
and the central stellar concentration. This tidal stability suggests a longer
lifetime for the CND. The higher densities and masses within the cores might
support star formation either in the CND itself or within a core infalling
toward the inner parsec, thus providing a mechanism for the formation of the
young stellar population in the inner arcseconds of the galaxy.


title:
VPMS J1342+2840 - an unusual quasar from the variability and proper
  motion survey

abstract:
  We report the discovery of the highly peculiar, radio-loud quasar VPMS
J1342+2840 (z ~ 1.3) from the variability and proper motion survey. We present
spectroscopic, imaging and photometric observations. The unusual spectrum shows
a strong depression of the continuum over a wide wavelength range in the blue
part without the typical structures of broad absorption line (BAL) troughs. The
image of the quasar is unresolved and there is no evidence for a foreground
object on the line of sight. The broad-band spectral energy distribution is not
consistent with obvious dust reddening with the standard SMC extinction curve.
The downturn of the continuum flux of VPMS J1342+2840 at short wavelengths can
be caused by dust reddening only if the reddening curve is steeper then the SMC
curve in the ultraviolet and is very flat at longer wavelengths. Alternatively,
the dominant spectral features can be explained by low-ionization BALs forming
unusually wide, overlapping absorption troughs.


title: Electric field representation of pulsar intensity spectra

abstract:
  Pulsar dynamic spectra exhibit high visibility fringes arising from
interference between scattered radio waves. These fringes may be random or
highly ordered patterns, depending on the nature of the scattering or
refraction. Here we consider the possibility of decomposing pulsar dynamic
spectra -- which are intensity measurements -- into their constituent scattered
waves, i.e. electric field components. We describe an iterative method of
achieving this decomposition and show how the algorithm performs on data from
the pulsar B0834+06. The match between model and observations is good, although
not formally acceptable as a representation of the data. Scattered wave
components derived in this way are immediately useful for qualitative insights
into the scattering geometry. With some further development this approach can
be put to a variety of uses, including: imaging the scattering and refracting
structures in the interstellar medium; interstellar interferometric imaging of
pulsars at very high angular resolution; and mitigating pulse arrival time
fluctuations due to interstellar scattering.


title:
Probing the circumstellar structures of T Tauri stars and their
  relationship to those of Herbig stars

abstract:
  We present Halpha spectropolarimetry observations of a sample of 10 bright T
Tauri stars, supplemented with new Herbig Ae/Be star data. A change in the
linear polarisation across Halpha is detected in most of the T Tauri (9/10) and
Herbig Ae (9/11) objects, which we interpret in terms of a compact source of
line photons that is scattered off a rotating accretion disk. We find
consistency between the position angle (PA) of the polarisation and those of
imaged disk PAs from infrared and millimetre imaging and interferometry
studies, probing much larger scales. For the Herbig Ae stars AB Aur, MWC 480
and CQ Tau, we find the polarisation PA to be perpendicular to the imaged disk,
which is expected for single scattering. On the other hand, the polarisation PA
aligns with the outer disk PA for the T Tauri stars DR Tau and SU Aur and FU
Ori, conforming to the case of multiple scattering. This difference can be
explained if the inner disks of Herbig Ae stars are optically thin, whilst
those around our T Tauri stars and FU Ori are optically thick. Furthermore, we
develop a novel technique that combines known inclination angles and our recent
Monte Carlo models to constrain the inner rim sizes of SU Aur, GW Ori, AB Aur,
and CQ Tau. Finally, we consider the connection of the inner disk structure
with the orientation of the magnetic field in the foreground interstellar
medium: for FU Ori and DR Tau, we infer an alignment of the stellar axis and
the larger magnetic field direction.


title:
Dust Distribution in Gas Disks II: Self Induced Ring Formation Through a
  Clumping Instability

abstract:
  Debris rings of dust are found around young luminous stars such as HR4796A
and HD141569. Some of these entities have sharp edges and gaps which have been
interpreted as evidence for the presence of shepherding and embedded planets.
Here we show that gaps and sharp edges in the debris disks of dust can also be
spontaneously self generated if they are embedded in optically thin regions of
gaseous disks. This clumping instability arises in regions where an enhancement
in the dust density leads to local gas temperature and pressure increases.
Consequently, the relative motion between the gas and the dust is modified. The
subsequent hydrodynamic drag on the dust particles leads to further enhancement
of their concentration. We show that this process is linearly unstable and
leads to the formation of ring-like structures within the estimated life time
of such young objects. Once the gas is removed (e.g. by photo evaporation) the
structures are ``frozen'' and will persist, even when the gas might not be
observable anymore.


title: The nature of the molecular gas system in the core of NGC 1275

abstract:
  We present near-infrared integral field spectroscopy of the central
kiloparsec of NGC 1275 at the heart of the Perseus cluster of galaxies,
obtained with the UIST IFU on UKIRT. The nuclear ro-vibrational H_2 emission is
spatially resolved and is likely to originate approximately 50 pc from the
active nucleus. The Pa-alpha emission is, by contrast, spatially unresolved.
The requirements for thermal excitation of the H_2 by nuclear X-radiation, its
kinematics on sub-arcsec scales, and its stability against self-gravity,
together suggest that the observed H_2 is part of a clumpy disk rotating about
the radio-jet axis. The sharp jump in H_2 velocity across the nucleus implies a
black hole mass of 3.4E8 M(Solar), with a systematic error of 0.18 dex due to
the uncertainty in the radio jet inclination. This agrees well with the value
implied by the empirical correlation between black hole mass and stellar
velocity dispersion for nearby elliptical galaxies, and is ~100 times the
stellar mass in this region.