title: A Highly Collimated, Young and Fast CO(2-1) Outflow in OMC1 South

abstract:
  We present high angular resolution (~ 1''), sensitive CO(2-1) line
observations of the region OMC1 South in the Orion Nebula made using the
Submillimeter Array (SMA). We detect the CO(2-1) high velocity outflow that was
first found by Rodriguez-Franco et al. (1999a) with the IRAM 30 m. Our
observations resolve the outflow, whose velocity-integrated emission has a
deconvolved width of 0.89'' \pm 0.06'' (490 AU) and a projected length of ~
48'' (21,000 AU) with very high redshifted and blueshifted gas with velocities
of about \pm 80 km/s. This outflow is among the most collimated (~ 3 degrees)
and youngest outflows (600 yr) that have been reported. The data show that this
collimated outflow has been blowing in the same direction during the last 600
yr. At high velocities, the CO(2-1) outflow traces an extremely collimated jet,
while at lower velocities the CO emission traces an envelope possibly produced
by entrainment of ambient gas. Furthermore, we also detect for the first time a
millimeter wavelength continuum source possibly associated with a class I
protostar that we suggest could be the possible exciting source for this
collimated outflow. However, the bolometric luminosity of this source appears
to be far too low to account for the powerful molecular outflow.


title:
A Statistically Robust 3-Sigma Detection of Non-Gaussianity in the WMAP
  Data Using Hot and Cold Spots

abstract:
  We present a careful frequentist analysis of one- and two-point statistics of
the hot and cold spots in the cosmic microwave background (CMB) data obtained
by the Wilkinson Microwave Anisotropy Probe (WMAP). Our main result is the
detection of a new anomaly at the 3-sigma level using temperature-weighted
extrema correlation functions. We obtain this result using a simple hypothesis
test which reduces the maximum risk of a false detection to the same level as
the claimed significance of the test. We further present a detailed study of
the robustness of our earlier claim (Larson and Wandelt 2004) under variations
in the noise model and in the resolution of the map. Free software which
implements our test is available online.


title: Environmental Dependencies in the Luminosity Function of Galaxies

abstract:
  The evidence is becoming strong that the luminosity function of galaxies
varies with environment. Higher density, more dynamically evolved regions
appear to have more dwarfs per giant. The situation is becoming clearer as a
result of wide field imaging surveys with the Canada-France-Hawaii and Subaru
telescopes and spectroscopy of faint dwarfs with the Keck telescope. We report
here on extensive observations of the small but dense NGC 5846 Group. The faint
end of the luminosity function rises relatively steeply in this case.


title: The colours of Virgo dEs as seen by SDSS

abstract:
  A colour analysis of a carefully selected sample of over 200 Virgo cluster
dEs and 8 giant ellipticals (Es) in the SDSS yields the following results: a)
the nucleated dEs (dENs) follow a tight colour-magnitude relation (CMR) which
does not broaden significantly at fainter (Mr > -15) magnitudes, b) the CMR of
dENs smoothly transitions to the CMR of Es, but the latter changes its slope at
about Mr = -20, c) the brighter dENs are consistent with ages of t > 5Gyr and a
decrease of metallicity towards fainter magnitudes, but a possible additional
luminosity-age relation is not ruled out, d) it is crucial to treat dS0s
separately from dEs since their different colour properties would otherwise
bias the comparison of nucleated and non-nucleated dEs (dEnoNs), e) the dEnoNs
show a weak trend towards bluer colours than dENs.


title:
Tracing the X-ray emitting intra-cluster medium of clusters of galaxies
  beyond r_200

abstract:
  (Abridged) We present in this paper a sample of 14 nearby clusters of
galaxies observed with the ROSAT/PSPC. We only select clusters with low
galactic nH in order to trace the X-ray emitting intra-cluster medium (ICM) out
to large radii. We convert the X-ray surface brightness profiles of the
clusters into emission measure profiles scaled to the classical scaling
relations based on the spherical collapse model. We sort the clusters into
different temperature bins and stack the scaled emission measure (ScEM)
profiles of clusters together. The stacked profiles allow us to observe out to
radii r>r_200. In the center we find that the ScEM profiles deviate from
predicted scaling laws. This result is in very good agreement with current
studies on the L_X-T relation and the entropy - temperature relation (S \propto
T^0.65) found recently. At radii r>0.4r_200 we find that the ScEM profiles
agree well within the error bars, suggesting self-similarity. Fitting
beta-models to the overall ScEM profiles we find for the different sub samples
r_c=0.15-0.18 r_200 and beta=0.8, which is higher than beta=2/3 often found.
The beta-model is generally a better representation for hotter than for cooler
clusters. We see indications for continuous steepening of the profiles with
increasing radius: at radii r>0.8r_200 the profiles are systematically below
the beta-model curve with beta=0.8. We discuss our results with respect to the
observed X-ray luminosity L_X-T relation, the gas mass M_gas-T relation and the
total mass M-T relation. We also address implications on the origin of the
observed S-T relation. Furthermore we discuss the observed steepness of the
X-ray profiles, which falls off more rapidly than predicted from the
NFW-profile for cold dark matter halos.


title:
The Hamburg/ESO R-process Enhanced Star survey (HERES) II. Spectroscopic
  analysis of the survey sample

abstract:
  We present the results of analysis of ``snapshot'' spectra of 253 metal-poor
halo stars -3.8 < [Fe/H] < -1.5 obtained in the HERES survey. The spectra are
analysed using an automated line profile analysis method based on the
Spectroscopy Made Easy codes of Valenti & Piskunov. Elemental abundances of
moderate precision have been obtained for 22 elements, C, Mg, Al, Ca, Sc, Ti,
V, Cr, Mn, Fe, Co, Ni, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, and Eu, where
detectable. Among the sample of 253 stars, we find 8 r-II stars and 35 r-I
stars. We also find three stars with strong enhancements of Eu which are
s-process rich. A significant number of new very metal-poor stars are
confirmed: 49 stars with [Fe/H] < -3 and 181 stars with -3 < [Fe/H] < -2. We
find one star with [Fe/H] < -3.5. We find the scatter in the abundance ratios
of Mg, Ca, Sc, Ti, Cr, Fe, Co, and Ni, with respect to Fe and Mg, to be similar
to the estimated relative errors and thus the cosmic scatter to be small,
perhaps even non-existent. The elements C, Sr, Y, Ba and Eu, and perhaps Zr,
show scatter at [Fe/H] < -2.5 significantly larger than can be explained from
the errors in the analysis, implying scatter which is cosmic in origin.
Significant scatter is observed in abundance ratios between light and heavy
neutron-capture elements at low metallicity and low levels of r-process
enrichment. (*** abridged ***)


title: Chandra's tryst with SN 1995N

abstract:
  We present the spectroscopic and imaging analysis of a type IIn supernova SN
1995N observed with the Chandra X-ray observatory on 2004 March 27. We compare
the spectrum obtained from our Chandra observation with that of the previous
observation with ASCA in 1998. We find the presence of Neon lines in the
Chandra spectrum that were not reported in the ASCA observation. We see no
evidence of Iron in both epochs. The observed absorption column depth indicates
an extra component over and above the galactic absorption component and is
possibly due to a cool dense shell between the reverse-shock and the contact
discontinuity in the ejecta. The ASCA and the ROSAT observations suggested a
non-linear behavior of the X-ray light curve. However, with the higher spatial
resolution and sensitivity of Chandra, we separate out many nearby sources in
the supernova field-of-view that had additionally contributed to the supernova
flux due to the large Point Spread Function of the ASCA. Taking out the
contribution of those nearby sources, we find that the light curves are
consistent with a linear decline profile. We consider the light curve in the
high energy band separately. We discuss our results in the context of models of
nucleosynthesis and the interaction of the shock waves with the circumstellar
medium in core collapse supernovae.


title:
SN/GRB connection: a statistical approach with BATSE and Asiago
  Catalogues

abstract:
  Recent observations suggest that some types of GRB are physically connected
with SNe of type Ib/c. However, it has been pointed out by several authors that
some GRBs could be associated also with other types of core-collapse SNe (type
IIdw/IIn). On the basis of a comphrensive statistical study, which has made use
of the BATSE and Asiago catalogues, we have found that: i) the temporal and
spacial distribution of SNe-Ib/c is marginally correlated with that of the
BATSE GRBs; ii) we do not confirm the existence of an association between GRBs
and SNe-IIdw/IIn.


title: Particle Effects on the ISGRI Instrument On-Board the INTEGRAL Satellite

abstract:
  The INTEGRAL satellite was launched on October 17, 2002. All on-board
instruments are operating successfully. In this paper, we focus on radiation
effects on the Cadmium Telluride camera ISGRI. The spectral response of the
camera is affected by cosmic particles depositing huge amount of energy,
greater than the high threshold of the electronics. Our study raises the
contribution of cosmic ray protons. Solutions are proposed to limit the
degradation of spectral response of large pixel gamma cameras operating in
space.


title: Hot-Jupiters and hot-Neptunes: a common origin?

abstract:
  We compare evolutionary models for close-in exoplanets coupling irradiation
and evaporation due respectively to the thermal and high energy flux of the
parent star with observations of recently discovered new transiting planets.
The models provide an overall good agreement with observations, although at the
very limit of the quoted error bars of OGLE-TR-10, depending on its age. Using
the same general theory, we show that the three recently detected hot-Neptune
planets (GJ436, $\rho$ Cancri, $\mu$ Ara) may originate from more massive gas
giants which have undergone significant evaporation. We thus suggest that
hot-Neptunes and hot-Jupiters may share the same origin and evolution history.
Our scenario provides testable predictions in terms of the mass-radius
relationships of these hot-Neptunes.


title: Tiny HI Clouds in the Local ISM

abstract:
  We report deep, high spectral resolution WSRT HI 21cm observations of four
high latitude compact radio sources, that have revealed a new population of
tiny, discrete clouds in the diffuse ISM, with peak optical depths tau ~
0.1-2%, HI column densities of 0.4-8 * 10^{18} cm^{-2} and core temperatures of
20-80 K. Imaging detections confirm these low column densities and imply linear
core dimensions of a few thousand AU, assuming a distance of 100 pc. The
physical origin of these tiny HI structures and their distribution in the ISM
is at present unknown. Further observations will be required to determine
whether they are a ubiquitous component of the ISM.


title: Similarity theory of stellar models and structure of very massive stars

abstract:
  The similarity theory of stellar structure is used to study the properties of
very massive stars when one can neglect all the sources of opacity except for
the Thomson scattering. The dimensionless internal structure of such stars is
practically independent of the energy generation law.
  It is shown that the mass-luminosity relation can be approximated by an
analytical expression which is virtually universal regarding the chemical
composition and energy generation law. A detailed comparison with the
  Eddington standard model is given. The application of the obtained results to
the observations of massive stars is briefly discussed.


title:
Modeling complete distributions with incomplete observations: The
  velocity ellipsoid from Hipparcos data

abstract:
  [abridged] A "missing data" algorithm is developed to model (ie, reconstruct)
the three-dimensional velocity distribution function of a sample of stars using
data (velocity measurements) every one of which has one dimension unmeasured
(the radial direction). It also accounts for covariant measurement
uncertainties on the tangential velocity components. The algorithm is applied
to tangential velocities measured in a kinematically unbiased sample of 11,865
stars taken from the Hipparcos catalog. The local stellar velocity distribution
function of each of a set of 20 color-selected subsamples is modeled as a
mixture of two three-dimensional Gaussian ellipsoids of arbitrary relative
responsibility. In the fitting, one Gaussian (the "halo") is fixed at the known
mean velocity and velocity variance tensor of the Galaxy halo, and the other
(the "disk") is allowed to take arbitrary mean and arbitrary variance tensor.
The mean and variance tensor (commonly the "velocity ellipsoid") of the disk
velocity distribution are both found to be strong functions of stellar color,
with long-lived populations showing larger velocity dispersion, slower mean
rotation velocity, and smaller vertex deviation than short-lived populations.
The local standard of rest (LSR) is inferred in the usual way and the Sun's
motion relative to the LSR is found to be
(U,V,W)_{\odot}=(10.1,4.0,6.7)+/-(0.5,0.8,0.2) km/s. Artificial data sets are
made and analyzed, with the same error properties as the Hipparcos data, to
demonstrate that the analysis is unbiased. The results are shown to be
insensitive to the assumption that the velocity distributions are Gaussian.


title: $\gamma$-ray flux from Dark Matter Annihilation in Galactic Caustics

abstract:
  In the frame of indirect dark matter searches we investigate the flux of
high-energy $\gamma$-ray photons produced by annihilation of dark matter in
caustics within our Galaxy under the hypothesis that the bulk of dark matter is
composed of the lightest supersymmetric particles. Unfortunately, the detection
of the caustics annihilation signal with currently available instruments is
rather challenging. Indeed, with realistic assumptions concerning particle
physics and cosmology, the $\gamma $-ray signal from caustics is below the
detection threshold of both $\check {\rm C}$erenkov telescopes and
satellite-borne experiments. Nevertheless, we find that this signal is more
prominent than that expected if annihilation only occurs in the smoothed
Galactic halo, with the possible exception of a $\sim 15^{\circ}$ circle around
the Galactic center if the mass density profile of our Galaxy exhibits a sharp
cusp there. We show that the angular distribution of this $\gamma$-ray flux
changes significantly if DM annihilation preferentially occurs within
virialized sub-halos populating our Galaxy rather than in caustics.


title:
Finding Young Stellar Populations in Elliptical Galaxies from
  Independent Components of Optical Spectra

abstract:
  Elliptical galaxies are believed to consist of a single population of old
stars formed together at an early epoch in the Universe, yet recent analyses of
galaxy spectra seem to indicate the presence of significant younger populations
of stars in them. The detailed physical modelling of such populations is
computationally expensive, inhibiting the detailed analysis of the several
million galaxy spectra becoming available over the next few years. Here we
present a data mining application aimed at decomposing the spectra of
elliptical galaxies into several coeval stellar populations, without the use of
detailed physical models. This is achieved by performing a linear independent
basis transformation that essentially decouples the initial problem of joint
processing of a set of correlated spectral measurements into that of the
independent processing of a small set of prototypical spectra. Two methods are
investigated: (1) A fast projection approach is derived by exploiting the
correlation structure of neighboring wavelength bins within the spectral data.
(2) A factorisation method that takes advantage of the positivity of the
spectra is also investigated. The preliminary results show that typical
features observed in stellar population spectra of different evolutionary
histories can be convincingly disentangled by these methods, despite the
absence of input physics. The success of this basis transformation analysis in
recovering physically interpretable representations indicates that this
technique is a potentially powerful tool for astronomical data mining.


title: Time variability of AGN and heating of cooling flows

abstract:
  There is increasing evidence that AGN mechanical feedback is important in the
energetics of cooling flows in galaxies and galaxy clusters. We investigate the
implications of the variability of AGN mechanical luminosity L_m on
observations of cooling flows and radio galaxies in general. It is natural to
assume that l=ln(L_m/L_x) is a Gaussian process. Then L_m will be log-normally
distributed at fixed cooling luminosity L_x, and the variance in a measure of
L_m will increase with the time-resolution of the measure. We test the
consistency of these predictions with existing data. These tests hinge on the
power spectrum of l(t). Monitoring of Seyfert galaxies combined with estimates
of the duty cycle of quasars imply flicker noise spectra, similar to those of
microquasars. We combine a sample of sources in cooling flows that have
cavities with the assumption that the average mechanical luminosity of the AGN
equals L_x. Given that the mechanical luminosities are characterized by flicker
noise, we find that their spectral amplitudes lie between the estimated
amplitudes of quasars and the measured values for the radio luminosities of
microquasars. The model together with the observation that powerful radio
galaxies lie within a narrow range in optical luminosity, predicts the
luminosity function of radio galaxies, in agreement with observations.
Forthcoming radio surveys will test the prediction that the luminosity function
turns over at about the smallest luminosities so far probed. [Abridged]


title:
A stability analysis of radiative shocks in the presence of a transverse
  magnetic field

abstract:
  Radiative shock waves may be subject to a global thermal instability in which
the cooling layer and shock front undergo growing resonant oscillations. For
strong hydrodynamic shocks, the presence of the overstability depends on the
temperature and density indices of power-law cooling functions and the specific
heat ratio, $\alpha$, $\beta$ and $\gamma$, respectively. Here, we investigate
the stabilising influence of a transverse magnetic field by introducing the
shock Alfv\'en number, $M_a$ as a fourth parameter. We thus investigate the
stability criteria for both molecular and atomic shocks under a wide range of
conditions. In particular, we find that all molecular shocks in which the
cooling increases with the temperature ($\alpha > 0$) are stabilised to the
first four modes if $M_a < 20$ ($\beta = 2$). For $\alpha = -0.5$, the first
overtone remains stable only for $M_a < 8$. We conclude that molecular shocks
in the interstellar medium are probably stabilised by a transverse magnetic
field unless exceptional circumstances arise in which the cooling strongly
increases as the gas cools.


title:
Formation of Resonant Atomic Lines during Thermonuclear Flashes on
  Neutron Stars

abstract:
  Motivated by the measurement of redshifted Fe H$\alpha$ lines during type I
X-ray bursts on EXO 0748-676 (Cottam, Paerels & Mendez), we study the formation
of atomic Fe lines above the photosphere of a bursting neutron star ($k_BT_{\rm
eff} \approx 1-2 {\rm keV}$). We discuss the effects of Stark broadening,
resonant scattering and NLTE (level population) on the formation of hydrogenic
Fe H$\alpha$, Ly$\alpha$ and P$\alpha$ lines. From the observed equivalent
width of the Fe H$\alpha$ line, we find an implied Fe column of $1-3 \times
10^{20} {\rm cm}^{-2}$, which is 3-10 times larger than the Fe column
calculated from the accretion/spallation model of Bildsten, Chang & Paerels. We
also estimate that the implied Fe column is about a factor of 2-3 larger than a
uniform solar metallicity atmosphere. We discuss the effects of rotational
broadening and find that the rotation rate of \EXO must be slow, as confirmed
by the recent measurement of a 45 Hz burst oscillation by Villarreal &
Strohmayer. We also show that the Fe Ly$\alpha$ EW $\approx$ 15-20 eV
(redshifted 11-15 eV) and the P$\alpha$ EW $\approx$ 4-7 eV (redshifted 3-5 eV)
when the H$\alpha$ EW is 10 eV (redshifted 8 eV). The Ly$\alpha$ line is
rotationally broadened to a depth of $\approx 10%$, making it difficult to
observe with {\it Chandra}. We also show that radiative levitation can likely
support the Fe column needed to explain the line.


title: 511 KeV photons from superconducting cosmic strings

abstract:
  We show that a tangle of light superconducting strings in the Milky Way could
be the source of the observed 511 KeV emission from electron-positron
annihilation in the Galactic bulge. The scenario predicts a flux that is in
agreement with observations if the strings are at the ~ 1 TeV scale making the
particle physics within reach of planned accelerator experiments. The emission
is directly proportional to the galactic magnetic field and future observations
should be able to differentiate the superconducting string scenario from other
proposals.


title:
The environment of dwarf spheroidal satellites; ram pressure, tides and
  external radiation fields

abstract:
  We discuss the role of environmental mechanisms in the evolution of dwarf
galaxy satellites using high-resolution N-Body+SPH simulations that include
simultaneously tidal forces, ram pressure and heating from ionizing radiation
fields. Tidally induced bar-buckling instabilities can transform a rotating
disky dwarf into a pressure supported spheroidal. Efficient gas removal
requires instead a combination of tidal mass loss and ram pressure stripping in
a diffuse gaseous corona around the primary system. The efficiency of ram
pressure depends strongly on how extended the gas remains during the evolution.
Bar driven inflows that tend to drive the gas to the bottom of the potential
well can be opposed by the heating from ultraviolet radiation. We show that
even fairly massive dwarfs ($V_{peak} >$ 30 km/s) would be stripped of their
gas over a few Gyr if they enter the Milky Way halo at $z > 2$ thanks to the
effect of the cosmic UV background. Gas mass loss can be much faster, occurring
in less than 1 Gyr, if dwarf satellites have their first close approach with
the primary at the epoch of bulge formation. Indeed at that time the primary
galaxy should have a FUV luminosity comparable to that of major present-day
starbursts, resulting in a local radiation field even more intense than the
cosmic background.


title: Taxing the Rich: Recombinations and Bubble Growth During Reionization

abstract:
  Reionization is inhomogeneous for two reasons: the clumpiness of the
intergalactic medium (IGM) and clustering of the discrete ionizing sources.
While numerical simulations can in principle take both into account, they are
at present limited by small box sizes. On the other hand, analytic models have
only examined the limiting cases of a clumpy IGM (with uniform ionizing
emissivity) and clustered sources (embedded in a uniform IGM). Here, we present
an analytic model for the evolving topology of reionization that includes both
factors. At first, recombinations can be ignored and ionized bubbles grow
primarily through major mergers. As a result, reionization resembles
"punctuated equilibrium," with a series of well-separated sharp jumps in the
ionizing background. These features are local effects and do not reflect
similar jumps in the global ionized fraction. We then combine our bubble model
with a simple description of recombinations in the IGM. We show that the
bubbles stop growing when recombinations balance ionizations. If the IGM
density structure is similar to that at moderate redshifts, this limits the
bubble radii to ~20 comoving Mpc; however, it may be much smaller if the IGM is
significantly clumpier at higher redshifts. Once a bubble reaches saturation,
that region of the universe has for all intents and purposes entered the
"post-overlap" stage, so the overlap epoch actually has a finite width. This
picture naturally explains the substantial large-scale variation in
Lyman-series opacity along the lines of sight to the known z>6 quasars. More
quasar spectra will shed light on the transition between the "bubble-dominated"
topology characteristic of reionization and the "web-dominated" topology
characteristic of the later universe. [Abridged]


title: Limits from the Hubble Space Telescope on a Point Source in SN 1987A

abstract:
  We observed supernova 1987A (SN 1987A) with the Space Telescope Imaging
Spectrograph (STIS) on the Hubble Space Telescope (HST) in 1999 September, and
again with the Advanced Camera for Surveys (ACS) on the HST in 2003 November.
No point source is observed in the remnant. We obtain a limiting flux of F_opt
< 1.6 x 10^{-14} ergs/s/cm^2 in the wavelength range 2900-9650 Angstroms for
any continuum emitter at the center of the supernova remnant (SNR). It is
likely that the SNR contains opaque dust that absorbs UV and optical emission,
resulting in an attenuation of ~35% due to dust absorption in the SNR. Taking
into account dust absorption in the remnant, we find a limit of L_opt < 8 x
10^{33} ergs/s. We compare this upper bound with empirical evidence from point
sources in other supernova remnants, and with theoretical models for possible
compact sources. Bright young pulsars such as Kes 75 or the Crab pulsar are
excluded by optical and X-ray limits on SN 1987A. Of the young pulsars known to
be associated with SNRs, those with ages < 5000 years are all too bright in
X-rays to be compatible with the limits on SN 1987A. Examining theoretical
models for accretion onto a compact object, we find that spherical accretion
onto a neutron star is firmly ruled out, and that spherical accretion onto a
black hole is possible only if there is a larger amount of dust absorption in
the remnant than predicted. In the case of thin-disk accretion, our flux limit
requires a small disk, no larger than 10^{10} cm, with an accretion rate no
more than 0.3 times the Eddington accretion rate. Possible ways to hide a
surviving compact object include the removal of all surrounding material at
early times by a photon-driven wind, a small accretion disk, or very high
levels of dust absorption in the remnant.


title: Latitudinal Shear Instabilities during Type I X-ray Bursts

abstract:
  Coherent oscillations have been observed during Type I X-ray bursts from 14
accreting neutron stars in low mass X-ray binaries, providing important
information about their spin frequencies. However, the origin of the brightness
asymmetry on the neutron star surface producing these oscillations is still not
understood. We study the stability of a zonal shearing flow on the neutron star
surface using a shallow water model. We show that differential rotation of >2%
between pole and equator, with the equator spinning faster than the poles, is
unstable to hydrodynamic shear instabilities. The unstable eigenmodes have
properties well-matched to burst oscillations: low azimuthal wavenumber m, wave
speeds 1 or 2% below the equatorial spin rate, and e-folding times close to a
second. Instability is related to low frequency buoyantly driven r-modes that
have a mode frequency within the range of rotation frequencies in the
differentially rotating shell. We discuss the implications for burst
oscillations. Growth of shear instabilities may explain the brightness
asymmetry in the tail of X-ray bursts, although some fine tuning of the level
of differential rotation and a spin frequency near 300 Hz are required in order
for the fastest growing mode to have m=1. If shear instabilities are to operate
during a burst, temperature contrasts of 30% across the star must be created
during ignition and spreading of the flash.


title: Second Data Release of the 6dF Galaxy Survey

abstract:
  The 6dF Galaxy Survey is measuring around 150000 redshifts and 15000 peculiar
velocities from galaxies over the southern sky at |b|>10 degrees. When
complete, it will be the largest survey of its kind by more than an order of
magnitude. Here we describe the characteristics of the Second Incremental Data
Release (DR2) and provide an update of the survey. This follows earlier data
made public in December 2002 and March 2004. A total of 83014 sources now have
their spectra, redshifts, near-infrared and optical photometry available online
and searchable through an SQL database at http://www-wfau.roe.ac.uk/6dFGS/.


title: The giant H-alpha/X-ray filament in the cluster of galaxies A1795

abstract:
  The cluster of galaxies A1795 hosts a 46 kpc-long filament at its core, which
is clearly visible in the light of H-alpha and X-ray emission. We present
optical slit spectroscopy and deeper Chandra X-ray data of the filament. The
optical spectra reveal that the the bulk of the filament is quiescent (with
sigma < 130 km/s), although considerable velocity structure is apparent around
the powerful radio source in the central cluster galaxy, where a direct
interaction is occurring between the radio plasma and the surrounding
intracluster medium. The filament contains a clump of UV/blue continuum halfway
along its length, which we resolve into a chain of at least 5 distinct knots
using archival HST images; the optical spectrum of this clump confirm it to be
mostly comprised of O stars. It is well-removed from the central galaxy and
radio source, and is most likely an example of a group of young star clusters
condensing directly from the cooling gas in the filament. The observed spatial
offset between these knots of star formation and the peak in the optical line
emission confirms that the massive star formation is most unlikely to be
responsible for the bulk of the observed emission-line luminosity in the
filament. Some other (as yet undetermined) source of energy is required to
power and maintain the optical line-emission, yet it must not completely impede
the cooling of the X-ray gas within the filament to form the star clusters.


title: On the nature of the X-ray source in GK Per

abstract:
  We report XMM-Newton observations of the intermediate polar (IP) GK Per on
the rise to the 2002 outburst and compare them to Chandra observations during
quiescence. We find an asymmetric spin light curve implying an asymmetric shape
of a semi-transparent accretion curtain. A low Fe xvii (15.01/15.26 A) line
flux ratio confirms the need for an asymmetric geometry and significant effects
of resonant line scattering. Medium resolution spectra in outburst and
quiescence are both fitted with a leaky absorber model for the post shock hard
X-ray emission, a black body (outburst) for the thermalized X-ray emission from
the white dwarf and an optically thin spectrum. The difference between high and
low spin as well as QPO/flares states can be explained by a variation in the
absorbing column density. The Fe fluorescence at 6.4 keV (equivalent width of
447 eV) is not significantly variable during spin cycle or on QPO periods.
High-resolution RGS spectra reveal a number of emission lines from H-like and
He-like elements. The lines are broader than the instrumental response with a
roughly constant velocity dispersion for different lines, indicating identical
origin. He-like emission lines are used to give values for the electron
densities of log n_e ~ 12. We do not detect any variation in the emission lines
during the spin cycle, implying that the lines are not noticeably obscured or
absorbed. We conclude that they originate in the accretion curtains and propose
a model for their shape.


title:
Global MHD Modelling of the ISM - From large towards small scale
  turbulence

abstract:
  Dealing numerically with the turbulent nature and non-linearity of the
physical processes involved in the ISM requires the use of sophisticated
numerical schemes coupled to HD and MHD mathematical models. SNe are the main
drivers of the interstellar turbulence by transferring kinetic energy into the
system. This energy is dissipated by shocks (which is more efficient) and by
molecular viscosity. We carried out adaptive mesh refinement simulations (with
a finest resolution of 0.625 pc) of the turbulent ISM embedded in a magnetic
field with mean field components of 2 and 3 $\mu$G. The time scale of our run
was 400 Myr, sufficiently long to avoid memory effects of the initial setup,
and to allow for a global dynamical equilibrium to be reached in case of a
constant energy input rate. It is found that the longitudinal and transverse
turbulent length scales have a time averaged (over a period of 50 Myr) ratio of
0.52-0.6, almost similar to the one expected for isotropic homogeneous
turbulence. The mean characteristic size of the larger eddies is found to be
\~75 pc in both runs. In order to check the simulations against observations,
we monitored the OVI and HI column densities within a superbubble created by
the explosions of 19 SNe having masses and velocities of the stars that
exploded in vicinity of the Sun generating the Local Bubble. The model
reproduces the FUSE absorption measurements towards 25 white dwarfs of the \ovi
column density as function of distance and of \nhi. In particular for lines of
sight with lengths smaller than 120 pc it is found that there is no correlation
between N(OVI) and N(HI).


title: Line profiles of molecular ions toward the pre-stellar core LDN 1544

abstract:
  Velocity profiles of ground state lines of H2D+, HC18O+ and N2H+, observed
previously with the CSO and IRAM 30m telescopes, are modeled with a Monte Carlo
radiative transfer program to study the temperature, density and velocity
structure of the pre-stellar core LDN 1544. The H2D+ line is double-peaked like
that of the other ions, but previous models that fit the HC18O+ and N2H+
profiles are found not to fit the H2D+ data. Matching the H2D+ observations
requires at least three modifications to the model at small radii: (1) the
density profile must continue to rise inward and not flatten off toward the
center; (2) the gas temperature must be nearly constant and not drop inwards
significantly; (3) the infall velocity must increase inward, in a fashion
intermediate between `quasi-static' (ambipolar diffusion) and `fully dynamic'
(Larson-Penston) collapse. The C18O emission indicates a chemical age of <~0.1
Myr. The effects of a flattened structure and rotation on the line profiles are
shown to be unimportant, at least on the scales probed by single-dish
telescopes. Alternatively, the H2D+ profile is affected by absorption in the
outer layers of the core, if gas motions in these layers are sufficiently
small.


title: Neutron Star Superfluidity, Dynamics and Precession

abstract:
  Basic rotational and magnetic properties of neutron superfluids and proton
superconductors in neutron stars are reviewed. The modes of precession of the
neutron superfluid are discussed in detail. We emphasize that at finite
temperature, pinning of superfluid vortices does not offer any constraint on
the precession. Any pinning energies can be surmounted by thermal activation
and there exists a dynamical steady state in which the superfluid follows the
precession of the crust at a small lag angle between the crust and superfluid
rotation velocity vectors. At this small lag the system is far from the
critical conditions for unpinning, even if the observed precession of the crust
may entail a large angle between the figure axis and the crust's rotation
velocity vector. We conclude that if long period modulations of pulse arrival
times and pulse shapes observed in a pulsar like the PSR B1828-11 are due to
the precession of the neutron star, this does not have any binding implications
about the existence of pinning by flux lines or the existence of Type II
superconductivity in the neutron star.


title: Redshift indicators for gamma-ray bursts

abstract:
  The measure of the distances and luminosities of gamma-ray bursts (GRBs) led
to the discovery that many GRB properties are strongly correlated with their
intrinsic luminosity, leading to the construction of reliable luminosity
indicators. These GRB luminosity indicators have quickly found applications,
like the construction of 'pseudo-redshifts', or the measure of luminosity
distances, which can be computed independently of the measure of the redshift.
In this contribution I discuss various issues connected with the construction
of luminosity-redshift indicators for gamma-ray bursts.


title: XMM-Newton spectroscopy of the metal depleted T Tauri star TWA 5

abstract:
  We present results of X-ray spectroscopy for TWA 5, a member of the young TW
Hydrae association, observed with XMM-Newton. TWA~5 is a multiple system which
shows Halpha emission, a signature typical of classical T Tauri stars, but no
infrared excess. From the analysis of the RGS and EPIC spectra, we have derived
the emission measure distribution vs. temperature of the X-ray emitting plasma,
its abundances, and the electron density. The characteristic temperature and
density of the plasma suggest a corona similar to that of weak-line T Tauri
stars and active late-type main sequence stars. TWA 5 also shows a low iron
abundance (~0.1 times the solar photospheric one) and a pattern of increasing
abundances for elements with increasing first ionization potential reminiscent
of the inverse FIP effect observed in highly active stars. The especially high
ratio Ne/Fe~10 is similar to that of the classical T Tauri star TW Hya, where
the accreting material has been held responsible for the X-ray emission. We
discuss the possible role of an accretion process in this scenario. Since all T
Tauri stars in the TW Hydrae association studied so far have very high Ne/Fe
ratios, we also propose that environmental conditions may cause this effect.


title:
Observation and modeling of anomalous CN polarization profiles produced
  by the molecular Paschen-Back effect in sunspots

abstract:
  We report novel spectropolarimetric observations of sunspots carried out with
the Tenerife Infrared Polarimeter (TIP) in a near-IR spectral region around
15410 A, which is known to contain two groups of prominent OH lines that show
circular polarization signals of opposite polarity. Surrounding these
well-known OH lines, we have discovered the presence of CN lines of the $\Delta
v=1$ band which show anomalous polarization profiles. Although the Stokes V
signals of the OH lines are antisymmetric and with a sizable amplitude, the CN
lines show almost negligible circular polarization. On the contrary, the linear
polarization signals turn out to be much stronger in the CN lines than in the
OH lines. Interestingly, these CN lines present striking antisymmetric linear
polarization profiles, which we are able to explain and model via the
Paschen-Back effect theory for diatomic molecules. The presence of such
peculiar CN lines in the same spectral region of the OH lines may be useful to
improve our empirical knowledge of solar magnetic fields via the simultaneous
observation and modeling of the transverse and longitudinal Zeeman effects in
two different molecular species.


title: A Minor Axis Surface Brightness Profile for M31

abstract:
  We use data from the Isaac Newton Telescope Wide Field Camera survey of M31
to determine the surface brightness profile of M31 along the south-east minor
axis. We combine surface photometry and faint red giant branch star counts to
trace the profile from the innermost regions out to a projected radius of 4
degrees (~55 kpc) where the V-band surface brightness is 32 mag per square
arcsec; this is the first time the M31 minor axis profile has been mapped over
such a large radial distance using a single dataset. We confirm the finding by
Pritchet & van den Bergh (1994) that the minor axis profile can be described by
a single de Vaucouleurs law out to a projected radius of 1.4 degrees or ~20
kpc. Beyond this, the surface brightness profile flattens considerably and is
consistent with either a power-law of index -2.3 or an exponential of
scalelength 14 kpc. The fraction of the total M31 luminosity contained in this
component is ~2.5%. While it is tempting to associate this outer component with
a true Population II halo in M31, we find that the mean colour of the stellar
population remains approximately constant at V-i~1.6 from 0.5-3.5 degrees along
the minor axis. This result suggests that the same metal-rich stellar
population dominates both structural components.


title:
The 1 - 50 keV spectral and timing analysis of IGR J18027-2016: an
  eclipsing, high mass X-ray binary

abstract:
  We report the association of the INTEGRAL source IGR J18027-2016 with the
BeppoSAX source SAX J1802.7-2017. IGR J18027-2016 is seen to be a weak,
persistent source by the IBIS/ISGRI instrument on board INTEGRAL with an
average source count rate of 0.55 counts s^-1 (~6.1 mCrab) in the 20-40 keV
band. Timing analysis performed on the ISGRI data identifies an orbital period
of 4.5696 +/- 0.0009 days and gives an ephemeris of mid-eclipse as, T{mid} =
52931.37 +/- 0.04 MJD. Re-analysis of archival BeppoSAX data has provided a
mass function for the donor star, f(m) = 16 +/- 1 M{sun} and a projected
semimajor axis of a{x}sin{i} = 68 +/- 1 lt-s. We conclude that the donor is an
OB-supergiant with a mass of 18.8-29.3 M{sun} and a radius of 15.0-23.4 R{sun}.
Spectra obtained by XMM-Newton and ISGRI indicate a high hydrogen column
density of NH = 6.8 x 10^22 cm^-2, which suggests intrinsic absorption. The
source appears to be a high mass X-ray binary with the neutron star emitting
X-rays through wind-fed accretion while in an eclipsing orbit around an
OB-supergiant.


title: The Distribution of Bar and Spiral Strengths in Disk Galaxies

abstract:
  The distribution of bar strengths in disk galaxies is a fundamental property
of the galaxy population that has only begun to be explored. We have applied
the bar/spiral separation method of Buta, Block, and Knapen to derive the
distribution of maximum relative gravitational bar torques, Q_b, for 147 spiral
galaxies in the statistically well-defined Ohio State University Bright Galaxy
Survey (OSUBGS) sample. Our goal is to examine the properties of bars as
independently as possible of their associated spirals. We find that the
distribution of bar strength declines smoothly with increasing Q_b, with more
than 40% of the sample having Q_b <= 0.1. In the context of recurrent bar
formation, this suggests that strongly-barred states are relatively short-lived
compared to weakly-barred or non-barred states. We do not find compelling
evidence for a bimodal distribution of bar strengths. Instead, the distribution
is fairly smooth in the range 0.0 <= Q_b < 0.8. Our analysis also provides a
first look at spiral strengths Q_s in the OSU sample, based on the same torque
indicator. We are able to verify a possible weak correlation between Q_s and
Q_b, in the sense that galaxies with the strongest bars tend also to have
strong spirals.


title:
Spatial and Temporal Variations in Small-Scale Galactic HI Structure
  Toward 3C~138

abstract:
  We present three epochs of VLBA observations of Galactic HI absorption toward
the quasar 3C~138 with resolutions of 20 mas (~ 10 AU). This analysis includes
VLBA data from observations in 1999 and 2002 along with a reexamination of 1995
VLBA data. Improved data reduction and imaging techniques have led to an order
of magnitude improvement in sensitivity compared to previous work. With these
new data we confirm the previously detected milliarcsecond scale spatial
variations in the HI opacity at the level of Delta(tau_{max}) =0.50 \pm 0.05.
The typical size scale of the optical depth variations is ~ 50 mas or 25 AU. In
addition, for the first time we see clear evidence for temporal variations in
the HI opacity over the seven year time span of our three epochs of data. We
also attempted to detect the magnetic field strength in the HI gas using the
Zeeman effect. From this analysis we have been able to place a 3 sigma upper
limit on the magnetic field strength per pixel of ~45 muG. We have also been
able to calculate for the first time the plane of sky covering fraction of the
small scale HI gas of ~10%. We also find that the line widths of the
milliarcsecond sizescale HI features are comparable to those determined from
previous single dish measurements toward 3C~138, suggesting that the opacity
variations cannot be due to changes in the HI spin temperature. From these
results we favor a density enhancement interpretation for the small scale HI
structures, although these enhancements appear to be of short duration and are
unlikely to be in equilibrium.


title:
Chandra Observation of the Unidentified TeV Gamma-Ray Source HESS
  J1303-631 in the Galactic Plane

abstract:
  The imaging atmospheric Cherenkov array H.E.S.S. recently discovered an
extended source in the 0.4$-$10 TeV energy range, HESS J1303-631. We obtained a
5 ks observation with the ACIS-I array on the Chandra X-ray observatory that
does not reveal an obvious compact or diffuse X-ray counterpart. Archival ROSAT
images are also blank in this region. Although there are several radio pulsars
within the field of HESS J1303-631, none is detected in X-rays to a flux limit
of $<5 \times 10^{-14}$ ergs cm$^{-2}$ s$^{-1}$, and none is a likely
counterpart on energetic grounds. Over the entire $17^{\prime} \times
17^{\prime}$ ACIS-I field, we place an upper limit of $<5.4 \times 10^{-12}$
ergs cm$^{-2}$ s$^{-1}$ on the excess diffuse flux in the 2-10 keV band. One
hard point-source with flux $\approx 4 \times 10^{-14}$ ergs cm$^{-2}$ s$^{-1}$
lies within $0.^{\prime}5$ of the centroid of the TeV emission. These
exploratory observations suggest that deeper pointings with Chandra and XMM are
needed before we can learn more about the nature of HESS J1303-631. Its
similarity to the unidentified source TeV J2032+4130 indicates the probable
existence of a new class of high-energy source in the Galactic plane that
originates from young, massive stars or their supernova remnants.


title: Destruction of formic acid by soft X-rays in star-forming regions

abstract:
  Formic acid is much more abundant in the solid state, both in interstellar
ices and cometary ices, than in the interstellar gas (ice/gas ~ 10^{4}) and
this point remains a puzzle. The goal of this work is to experimentally study
ionization and photodissociation processes of HCOOH (formic acid), a glycine
precursor molecule. The measurements were taken at the Brazilian Synchrotron
Light Laboratory (LNLS), employing soft X-ray photons from toroidal grating
monochromator TGM) beamline (200 - 310 eV). Mass spectra were obtained using
photoelectron photoion coincidence (PEPICO) method. Kinetic energy
distributions and abundances for each ionic fragment have been obtained from
the analysis of the corresponding peak shapes in the mass spectra.
Photoionization and photodissociation cross sections were also determined. Due
to the large photodissociation cross section of HCOOH it is possible that in
PDRs regions, just after molecules evaporation from the grain surface, formic
acid molecules are almost totally destroyed by soft X-rays, justifying the
observed low abundance of HCOOH in the gaseous phase. The preferential path for
the glycine formation from formic acid may be through the ice phase reaction.
  Keywords: HCOOH; Photoionization; X-rays; Astrochemistry.


title:
Inertial Current Generators of Poynting Flux in MHD Simulations of Black
  Hole Ergospheres

abstract:
  This Letter investigates the physics that is responsible for creating the
current system that supports the outgoing Poynting flux emanating from the
ergosphere of a rotating black hole in the limit that the magnetic energy
density greatly exceeds the plasma rest mass density (magnetically dominated
limit). The underlying physics is derived from published three-dimensional
simulations that obey the general relativistic equations of perfect
magnetohydrodynamics (MHD). It is found that the majority of the Poynting flux
emitted from the magnetically dominated regions of the ergosphere has a source
associated with inertial effects outside of the event horizon.


title: Globally integrated measurements of the Earth's visible spectral albedo

abstract:
  We report spectroscopic observations of the earthshine reflected from the
Moon. By applying our photometry methodology to spectroscopy, we were able to
precisely determine the Earth's reflectance, and its variation as a function of
wavelength through a single night as the Earth rotates. These data imply that
planned regular monitoring of earthshine spectra will yield valuable, new
inputs for climate models, which would be complementary to those from the more
standard broadband measurements of satellite platforms. The mean spectroscopic
albedo over the visible is consistent with simultaneous broadband photometric
measurements. We found no evidence for an appreciable "red" or "vegetation
edge" in the Earth's spectral albedo, and no evidence for changes in this
spectral region (700 -740 nm) over the 40 degrees of Earth's rotation covered
by our observations.


title:
Magnetic White Dwarfs from the SDSS II. The Second and Third Data
  Releases

abstract:
  Fifty-two magnetic white dwarfs have been identified in spectroscopic
observations from the Sloan Digital Sky Survey (SDSS) obtained between mid-2002
and the end of 2004, including Data Releases 2 and 3. Though not as numerous
nor as diverse as the discoveries from the first Data Release, the collection
exhibits polar field strengths ranging from 1.5MG to ~1000MG, and includes two
new unusual atomic DQA examples, a molecular DQ, and five stars that show
hydrogen in fields above 500MG. The highest-field example, SDSSJ2346+3853, may
be the most strongly magnetic white dwarf yet discovered. Analysis of the
photometric data indicates that the magnetic sample spans the same temperature
range as for nonmagnetic white dwarfs from the SDSS, and support is found for
previous claims that magnetic white dwarfs tend to have larger masses than
their nonmagnetic counterparts. A glaring exception to this trend is the
apparently low-gravity object SDSSJ0933+1022, which may have a history
involving a close binary companion.


title: Limits of Adaptive Optics for high contrast imaging

abstract:
  The effects of photon noise, aliasing, wavefront chromaticity and
scintillation on the point spread function (PSF) contrast achievable with
ground based adaptive optics (AO) are evaluated for different wavefront sensing
schemes. I show that a wavefront sensor (WFS) based upon the Zernike phase
contrast technique offers the best sensitivity to photon noise at all spatial
frequencies, while the Shack-Hartmann WFS is significantly less sensitive. In
AO systems performing wavefront sensing in the visible and scientific imaging
in the near-IR, the PSF contrast limit is set by the scintillation chromaticity
induced by Fresnel propagation through the atmosphere. On a 8m telescope, the
PSF contrast is then limited to 1e-4 to 1e-5 in the central arcsecond.
Wavefront sensing and scientific imaging should therefore be done at the same
wavelength, in which case, on bright sources, PSF contrasts between 1e-6 and
1e-7 can be achieved within 1 arcsecond on a 8m telescope in optical/near-IR.
The impact of atmospheric turbulence parameters (seeing, wind speed, turbulence
profile) on the PSF contrast is quantified. I show that a focal plane wavefront
sensing scheme offers unique advantages, and I discuss how to implement it.
Coronagraphic options are also briefly discussed.


title: GRACOS: Scalable and Load Balanced P3M Cosmological N-body Code

abstract:
  We present a parallel implementation of the particle-particle/particle-mesh
(P3M) algorithm for distributed memory clusters. The GRACOS (GRAvitational
COSmology) code uses a hybrid method for both computation and domain
decomposition. Long-range forces are computed using a Fourier transform gravity
solver on a regular mesh; the mesh is distributed across parallel processes
using a static one-dimensional slab domain decomposition. Short-range forces
are computed by direct summation of close pairs; particles are distributed
using a dynamic domain decomposition based on a space-filling Hilbert curve. A
nearly-optimal method was devised to dynamically repartition the particle
distribution so as to maintain load balance even for extremely inhomogeneous
mass distributions. Tests using $800^3$ simulations on a 40-processor beowulf
cluster showed good load balance and scalability up to 80 processes. We discuss
the limits on scalability imposed by communication and extreme clustering and
suggest how they may be removed by extending our algorithm to include adaptive
mesh refinement.


title: The Warped Circumstellar Disk of HD100546

abstract:
  We propose that the two armed spiral features seen in visible Hubble Space
Telescope images of scattered light in HD100546's circumstellar disk are caused
by the illumination of a warped outer disk. A tilt of 6-15 degrees from the
symmetry plane can cause the observed surface brightness variations providing
the disk is very twisted (highly warped) at radii greater than 200 AU where the
spiral features are seen. Dust lanes are due in part to shadowing in the
equatorial plane from the inner disk within a radius of 100 AU. HD100546's
outer disk, if viewed edge-on, would appear similar to that of Beta Pictorus. A
disk initially misaligned with a planetary system, becomes warped due to
precession induced by planetesimal bodies and planets. However, the twistedness
of HD100546's disk cannot be explained by precession during the lifetime of the
system induced by a single Jovian mass planet within the clearing at ~13 AU.
One possible explanation for the corrugated disk is that precession was induced
by massive of bodies embedded in the disk at larger radius. This would require
approximately a Jupiter mass of bodies well outside the central clearing at 13
AU and within the location of the spiral features or at radii approximately
between 50-200 AU.


title: Theoretical Isochrones with Extinction in the K Band

abstract:
  We calculate theoretical isochrones in a consistent way for five filters (K,
K', Ks, F205W, and F222M) in the atmospheric window between 1.9 and 2.5 micron
using the Padova stellar evolutionary models by Girardi et al. Even when
displayed in the same Vega magnitude system, the near-infrared colors of the
same isochrone can differ by up to 0.18 mag at its bright end, depending on the
filter. We present magnitude transformations between K-band filters as a
function of color from H and K band filters. Isochrones with extinction at K of
up to 6 mag are also presented. We find that care is needed when comparing
extinction values that are estimated using different filter sets in the K band,
in particular when comparing those of atmospheric and space filter sets:
extinction values for space filters can be in error by up to 0.3 mag. To reduce
this error, we introduce an "effective extinction slope" for each filter set
and isochrone model, which describes the extinction behavior of isochrones in
the color-magnitude diagram more correctly than the actual extinction law. Our
calculation also suggests that the extinction law implied by the observations
of Rieke et al. for wavelengths between the H and K bands is better described
by a power-law function with an exponent of 1.61 instead of 1.55, which is
commonly used with an assumption that the transmission functions of H and K
filters are Dirac delta functions.


title: VLT/UVES shows no cosmological variability of alpha

abstract:
  The cosmological variability of alpha is probed from individual observations
of pairs of FeII lines. This procedure allows a better control of the
systematics and avoids the influence of the spectral shifts due to ionization
inhomogeneities in the absorbers and/or non-zero offsets between different
exposures. Applied to the FeII lines of the metal absorption systems at zabs =
1.839 in Q1101--264 and at zabs = 1.15 in HE0515--4414 observed by means of
UVES at the ESO-VLT, it provides da/a = 0.4 (+/- 1.5 stat)x10^{-6}. The result
is shifted with respect to the Keck/HIRES mean da/a = -5.7(+/- 1.1
stat})x10^{-6} (Murphy et al. 2004) at a high confidence level (95%). Full
details of this work are given in Levshakov et al (2005)


title: Rotation of the cluster of galaxies A2107

abstract:
  We present indications of rotation in the galaxy cluster A2107 by a method
that searches for the maximum gradient in the velocity field in a flat
disk-like model of a cluster. Galaxies from cumulative sub-samples containing
more and more distant members from the cluster centre, are projected onto an
axis passing through the centre and we apply a linear regression model on the
projected distances $x$ and the line-of-sight velocities $V$. The axis with the
maximum linear correlation coefficient $r_{max} = \max [ r(V,x) ]$ defines the
direction of the maximum velocity gradient, and consequently it presents the
major axis of the apparently elliptical cluster. Because the effects of
rotation are subtle, we put strong emphasis on the estimation of the
uncertainties of the results by implementing different bootstrap techniques. We
have found the rotational effects are more strongly expressed from distances
$0.26 \div 0.54$ Mpc from the cluster centre. The total virial mass of the
cluster is $(3.2\pm0.6)\times10^{14} {\cal M}_{\sun}$, while the virial mass,
corrected for the rotation, is $(2.8\pm0.5) \times 10^{14}{\cal M}_{\sun}$.


title: The Spatial Orientation of Planetary Nebulae Within the Milky Way

abstract:
  We analyze the spatial orientation of a homogenous sample of 440 elongated
Planetary Nebulae (PNe) in order to determine the orientation of their apparent
major axis respect to the Milky Way plane. We present some important
geometrical and statistical considerations that have been overlooked by the
previous works on the subject. The global distribution of galactic position
angles (GPA) of PNe is quantitatively not very different from a random
distribution of orientations in the Galaxy. Nevertheless we find that there is
at least one region on the sky, toward the galactic center, where a weak
correlation may exist between the orientation of the major axis of some PNe and
the Galactic equator, with an excess of axes with GPA$\sim 100^{\circ}$.
Therefore, we confirm that ``extrinsic'' phenomena (i.e., global galactic
magnetic fields, shell compression from motion relative to the Interstellar
Medium) do not determine the morphology of PNe on most of the sky, with a
possible exception towards the galactic center.


title: CLASS B0631+519: Last of the CLASS lenses

abstract:
  We report the discovery of a new gravitational lens system from the CLASS
survey, CLASS B0631+519. VLA, MERLIN and VLBA observations show a doubly-imaged
radio core, a doubly-imaged lobe and a second lobe that is probably
quadruply-imaged. The maximum image separation is 1.16 arcseconds. The VLBA
resolves the most magnified image of the flat-spectrum radio core into a number
of sub-components spread across approximately 20 milli-arcseconds. Optical and
near-infrared imaging with the ACS and NICMOS cameras on the HST show that
there are two galaxies along the line of sight to the lensed source, as was
previously discovered by optical spectroscopy. The nearer galaxy at z=0.0896 is
a small blue irregular, while the more distant galaxy at z=0.6196 is an
elliptical type and appears to contribute most of the lensing effect. The host
galaxy of the lensed source is visible in NICMOS imaging as a set of arcs that
form an almost complete Einstein ring. Mass modelling using non-parametric
techniques can reproduce the ring and indicates that the irregular galaxy has a
(localised) effect on the flux density distribution in the Einstein ring at the
5-10% level.


title: Prompt Mergers of Neutron Stars with Black Holes

abstract:
  Mergers of neutron stars with black holes have been suggested as candidates
for short gamma-ray bursts. They have also been studied for their potential as
gravitational wave sources observable with ground-based detectors. For these
purposes, it is important to know under what circumstances such a merger could
leave an accretion disk or result in a period of stable mass transfer. We show
that, consistent with recent numerical simulations, it is expected that mergers
between neutron stars and black holes will be prompt, with no accretion disk
and no stable mass transfer, if the black hole has a mass greater than that of
the neutron star and is spinning slowly. The reason is that for comparable
masses, angular momentum loss to gravitational radiation starts a plunge orbit
well outside the innermost stable circular orbit, causing direct merging rather
than extended mass transfer. Even when the black hole is spinning rapidly and
exactly prograde with respect to the orbit, we show that it is possible within
current understanding that no accretion disk will form under any circumstances,
but resolution of this will require full general relativistic numerical
simulations with no approximations.


title: Modeling the formation of galaxy clusters in MOND

abstract:
  We use a one dimensional hydrodynamical code to study the evolution of
spherically symmetric perturbations in the framework of Modified Newtonian
Dynamics (MOND). The code evolves spherical gaseous shells in an expanding
Universe by employing a MOND-type relationship between the fluctuations in the
density field and the gravitational force, $g$. We focus on the evolution of
initial density perturbations of the form $\delta_{i}\sim r_{i}^{-s}$ for
$0<s<3$. A shell is initially cold and remains so until it encounters the shock
formed by the earlier collapse of shells nearer to the centre. During the early
epochs $g$ is sufficiently large and shells move according to Newtonian
gravity. As the physical size of the perturbation increases with time, $g$ gets
smaller and the evolution eventually becomes MOND dominated. However, the
density in the inner collapsed regions is large enough that they re-enter the
Newtonian regime. The evolved gas temperature and density profiles tend to a
universal form that is independent of the the slope, $s$, and of the initial
amplitude. An analytic explanation of this intriguing result is offered. Over a
wide range of scales, the temperature, density and entropy profiles in the
simulations, depend on radius roughly like $r^{0.5}$, $r^{-1.5}$ and $r^{1.5}$,
respectively. We compare our results with XMM-{\it Newton} and {\it Chandra}
observations of clusters. The temperature profiles of 16 observed clusters are
either flat or show a mild decrease at $R\gtsim 200\rm kpc$. MOND profiles show
a significant increase that cannot reconciled with the data. Our simulated MOND
clusters are substantially denser than the observed clusters. It remains to be
seen whether these difficulties persist in three-dimensional hydrodynamical
simulations with generic initial conditions.


title: Curvature driven acceleration : a utopia or a reality ?

abstract:
  The present work shows that a combination of nonlinear contribution from the
Ricci curvature in Einstein field equations can drive a late time acceleration
of expansion of the universe. The transit from the decelerated to the
accelerated phase of expansion takes place smoothly without having to resort to
a study of asymptotic behaviour. This result emphasizes the need for thorough
and critical examination of models with nonlinear contribution from the
curvature.


title:
Evidence of polarisation in the prompt gamma-ray emission from GRB
  930131 and GRB 960924

abstract:
  The true nature of the progenitor to GRBs remains elusive; one characteristic
that would constrain our understanding of the GRB mechanism considerably is
gamma-ray polarimetry measurements of the initial burst flux. We present a
method that interprets the prompt GRB flux as it Compton scatters off the
Earth's atmosphere, based on detailed modelling of both the Earth's atmosphere
and the orbiting detectors. The BATSE mission aboard the \textit{CGRO}
monitored the whole sky in the 20 keV - 1 MeV energy band continuously from
April 1991 until June 2000. We present the BATSE Albedo Polarimetry System
(BAPS), and show that GRB 930131 and GRB 960924 provide evidence of
polarisation in their prompt flux that is consistent with degrees of
polarisation of $\Pi>35$% and $\Pi>50$% respectively. While the evidence of
polarisation is strong, the method is unable to strongly constrain the degree
of polarisation beyond a systematics based estimation. Hence the implications
on GRB theory are unclear, and further measurements essential.


title:
To see or not to see a Bow Shock: Identifying Bow Shocks with H-Alpha
  Allsky Surveys

abstract:
  OB-stars have the highest luminosities and strongest stellar winds of all
stars, which enables them to interact strongly with their surrounding ISM, thus
creating bow shocks. These offer us an ideal opportunity to learn more about
the ISM. They were first detected and analysed around runaway OB-stars using
the IRAS allsky survey by van Buren et al. (1995). Using the geometry of such
bow shocks information concerning the ISM density and its fluctuations can be
gained from such infrared observations. As to help to improve the bow shock
models, additional observations at other wavelengths, e.g. H-Alpha, are most
welcome. However due to their low velocity these bow shocks have a size of ~1
degrees, and could only be observed as a whole with great difficulties. In the
light of the new H-Alpha allsky surveys (SHASSA/VTSS) this is no problem any
more. We developed different methods to detect bow shocks, e.g. the improved
determination of their symmetry axis with radial distance profiles. Using two
H-Alpha-allsky surveys (SHASSA/VTSS), we searched for bow shocks and compared
the different methods. From our sample we conclude, that the correlation
between the direction of both proper motion and the symmetry axis determined
with radial distance profile is the most promising detection method. We found
eight bow shocks around HD 17505, HD 24430, HD 48099, HD 57061, HD 92206, HD
135240, HD 149757, and HD 158186 from 37 candidates taken from van Buren et al.
(1995). Additionally to the traditional determination of ISM parameters using
the standoff distance of the bow shock, another approach was chosen, using the
thickness of the bow-shock layer. Both methods lead to the same results,
yielding densities (~1 cm^{-3}) and the maximal temperatures (~10^4 K), that
fit well to the up-to-date picture of the Warm Ionised Medium.


title:
Revised orbital parameters of the accreting millisecond pulsar SAX
  J1808.4-3658

abstract:
  We present temporal analysis of the three outbursts of the X-ray millisecond
pulsar SAX J1808.4-3658 that occurred in 1998, 2000 and 2002. With a technique
that uses the chi^2 obtained with an epoch folding search to discriminate
between different possible orbital solutions, we find an unique solution valid
over the whole five years period for which high temporal resolution data are
available. We revise the estimate of the orbital period, P_orb =7249.1569(1) s
and reduce the corresponding error by one order of magnitude with respect to
that previously reported. Moreover we report the first constraint on the
orbital period derivative, -6.6 x 10^-12 < Pdot < +0.8 x 10^-12 s/s. These
values allow us to produce, via a folding technique, pulse profiles at any
given time. Analysis of these profiles shows that the pulse shape is clearly
asymmetric in 2002, occasionally showing a secondary peak at about 145 degrees
from the main pulse, which is quite different from the almost sinusoidal shape
reported at the beginning of the 1998 outburst.


title:
VLT-FORS1 Imaging Polarimetry of M83 (NGC 5236) - I. Search for Light
  Echoes from Historical Supernovae

abstract:
  We have used FORS1 at the ESO VLT to search for light echoes in imaging
polarimetry from four historical supernovae in the face-on nearby spiral galaxy
M83 (NGC 5236). No echoes were detected around our targets (SN 1923A, SN 1945B,
SN 1950B and SN 1957D). This implies that the interstellar medium in their
environs is rather tenuous (a few particles/cm^3), possibly as a result of
previous supernova explosions that could have cleared the immediate vicinities
of our targets. The merits and limitations of searching for light echoes in
imaging polarimetry are discussed. From the photometry of the sources detected
at the supernova locations, we estimate star cluster masses of 720, 400, 300 Mo
for the cluster progenitors of SN 1957D, SN 1923A, and SN 1950B, respectively,
and an upper limit of few tens of solar masses for SN 1945B.


title: Spitzer view on the evolution of star-forming galaxies from z=0 to z~3

abstract:
  We use a 24 micron selected sample containing more than 8,000 sources to
study the evolution of star-forming galaxies in the redshift range from z=0 to
z~3. We obtain photometric redshifts for most of the sources in our survey
using a method based on empirically-built templates spanning from ultraviolet
to mid-infrared wavelengths. The accuracy of these redshifts is better than 10%
for 80% of the sample. The derived redshift distribution of the sources
detected by our survey peaks at around z=0.6-1.0 (the location of the peak
being affected by cosmic variance), and decays monotonically from z~1 to z~3.
We have fitted infrared luminosity functions in several redshift bins in the
range 0<z<~3. Our results constrain the density and/or luminosity evolution of
infrared-bright star-forming galaxies. The typical infrared luminosity (L*)
decreases by an order of magnitude from z~2 to the present. The cosmic star
formation rate (SFR) density goes as (1+z)^{4.0\pm0.2} from z=0 to z=0.8. From
z=0.8 to z~1.2, the SFR density continues rising with a smaller slope. At
1.2<z<3, the cosmic SFR density remains roughly constant. The SFR density is
dominated at low redshift (z<0.5) by galaxies which are not very luminous in
the infrared (L_TIR<1.e11 L_sun, where L_TIR is the total infrared luminosity,
integrated from 8 to 1000 micron). The contribution from luminous and
ultraluminous infrared galaxies (L_TIR>1.e11 L_sun) to the total SFR density
increases steadily from z~0 up to z~2.5, forming at least half of the
newly-born stars by z~1.5. Ultraluminous infrared galaxies (L_TIR>1.e12 L_sun)
play a rapidly increasing role for z>~1.3.


title:
General Astrophysics and Comparative Planetology with the Terrestrial
  Planet Finder Missions

abstract:
  The two Terrestrial Planet Finder (TPF) missions aim to perform spectroscopy
on extrasolar Earths; TPF-C will operate in visible light, and TPF-I will
operate in the mid-infrared. Extrasolar Earths are assumed to be roughly 26
magnitude in V band, roughly 0.3 microJy in the mid-IR, and located as close as
roughly 30 milliarcseconds from a reasonable set of target stars, demanding
high sensitivity, angular resolution and dynamic range to study. With
capabilities matched to this task, the TPF missions could easily undertake a
broad range of further scientific investigations. This document discusses the
potential of TPF for general astrophysics and comparative planetology beyond
its base mission, focusing on science obtainable with no or minimal
modifications to the mission design, but also exploring possible modifications
to TPF with high scientific merit and no impact on the basic search for
extrasolar Earth analogs. It addresses both TPF-C and TPF-I, but emphasizes
TPF-C, because its launch is planned for 2015, while TPF-I s nominal launch
date is in 2019. This document does not attempt to describe all of the
astrophysics TPF will be capable of, only to present some highlights of a
meeting held at Princeton University, April 14 15, 2004, and some discussions
that followed from that meeting.


title:
Mapping the Kinematics of the Narrow-Line Region in the Seyfert Galaxy
  NGC 4151

abstract:
  Using The Hubble Space Telescope's Space Telescope Imaging Spectrograph HST's
STIS, observations of the OIII emission from the narrow-line region (NLR) of
NGC 4151 were obtained and radial velocities determined. Five orbits of HST
time were used to obtain spectra at five parallel slit configurations, at a
position angle of 58 degrees, with spatial resolution 0.2 arcseconds across and
0.1 arcseconds along each slit. A spectral resolving power of ~ 9,000 with the
G430M grating gave velocity measurements accurate to ~ 34 km/s. A kinematic
model was generated to match the radial velocities, for comparison to previous
kinematic models of biconical radial outflow developed for low-dispersion
spectra at two slit positions. The new high-resolution spectra permit the
measurement of accurate velocity dispersions for each radial-velocity
component. The full-width at half-maximum (FWHM) reaches a maximum of 1000 km/s
near the nucleus, and generally decreases with increasing distance to about 100
km/s in the extended narrow-line region (ENLR), starting at about 6 arcseconds
from the nucleus. In addition to the bright emission knots, which generally fit
our model, there are faint high velocity clouds which do not fit the biconical
outflow pattern of our kinematic model. These faint clouds occur at the
turnover points of the outflowing bright clouds. We suggest possible scenarios
that could explain these rogue clouds: (1) backflow resulting from shocks and
(2) outflow outside of the bicones, although the latter does not explain how
the knots are ionized and accelerated. A comparison of our observations with a
high-resolution radio map shows that there is no evidence that the kinematics
of the NLR clouds are affected by the radio lobes that comprise the inner jet.


title:
Extragalactic Globular Clusters in the Near-Infrared: V. IC 4051 and NGC
  3311

abstract:
  We present the results of combined optical and near-infrared photometry for
the globular cluster systems of the giant ellipticals IC 4051 and NGC 3311. We
use the reduced age-metallicity degeneracy in (V-I) vs.(V-H) color-color
diagrams to derive the cumulative age distribution within the red
sub-population of globular clusters and to search for age sub-populations. The
age distribution is then compared to the one determined for simulated globular
cluster systems in order to set constraints on the relative age and size of
these globular cluster sub-populations. In both galaxies we find a significant
fraction of globular clusters with ages between 2- 5 Gyr. We also investigate
the metallicity distribution in both systems. Small number statistics prevent
us from making any definite statements concerning NGC 3311, but we find that
the derived metallicity distribution of the IC 4051 clusters strongly depends
on the assumed age distribution. Based on our most likely result that finds a
large number of young/intermediate age clusters (~2 Gyr) within the selected
globular cluster sample, we find metallicity peaks at $\sim$ -0.2 for the old
clusters and +0.8 for the young clusters. Only few very metal poor clusters are
found. However, the metallicity distribution within the young/intermediate
globular cluster population is significantly affected by our choice of the
applied Single Stellar Population model. The mean metallicity of the second
generation of globular clusters changes from the above mentioned and extremely
high +0.8 dex to +0.2 dex. Note that the model dependency becomes less severe
with an increasing age of the cluster population.


title:
Near-Infrared photometry of four metal-rich Bulge globular clusters:
  NGC6304, NGC6569, NGC6637, NGC6638

abstract:
  We present high-quality near-Infrared photometry of four Bulge metal-rich
globular clusters, namely: NGC 6304, NGC 6569, NGC 6637 and NGC 6638. By using
the observed Colour-Magnitude Diagrams we derived a photometric estimates of
the cluster reddening and distance. We performed a detailed analysis of the Red
Giant Branch, presenting a complete description of morphologic parameters and
evolutionary features (Bump and Tip). Photometric estimates of the cluster
metallicity have been obtained by using the updated set of relations (published
by our group) linking the metal abundance to a variety of near-Infrared indices
measured along the Red Giant Branch. The detection of the Red Giant Branch Bump
and the Tip is also presented and briefly discussed.


title: The thinnest cold HI clouds in the diffuse interstellar medium?

abstract:
  We confirm and discuss recently discovered cold HI clouds with column
densities among the lowest ever detected. The column densities of Cold Neutral
Medium (CNM) towards 3C286 and 3C287 are ~10^18 cm^-2, below an observational
lower limit, and also below tiny-scale-atomic clouds detected by VLBI and
time-variable profiles against pulsars. These column densities are close to the
minimum imposed by thermal evaporation. The fractions of the CNM to total HI
towards 3C286 and 3C287 are ~4% and <2%, respectively. We discuss the CNM
fraction and the CNM clouds in relation to several theoretical models.


title: The Afterglows, Redshifts, and Properties of Swift Gamma-Ray Bursts

abstract:
  We present optical, near-IR, and radio follow up of sixteen Swift bursts,
including our discovery of nine afterglows and a redshift determination for
three. These observations, supplemented by data from the literature, provide an
afterglow recovery rate of 60% in the optical/near-IR, much higher than in
previous missions (BeppoSAX, HETE-2, INTEGRAL, and IPN). The optical/near-IR
afterglows of Swift events are on average 1.7 mag fainter at t=12 hr than those
of previous missions. The X-ray afterglows are similarly fainter compared to
those of pre-Swift bursts. In the radio the limiting factor is the VLA
threshold and the detection rate for Swift bursts is similar to that for past
missions. The redshift distribution of pre-Swift bursts peaked at z~1, whereas
the five Swift bursts with measured redshifts are distributed evenly between
1.3 and 3.2. From these results we conclude that (i) the pre-Swift
distributions were biased in favor of bright events and low redshift events,
(ii) the higher sensitivity and accurate positions of Swift result in a better
representation of the true burst redshift and brightness distributions (which
are higher and dimmer, respectively), and (iii) as many as 1/3 of the bursts
can be optically dark, as a result of a high redshift and/or dust extinction.
We remark that the apparent lack of low redshift, low luminosity Swift bursts,
and the lower event rate compared to pre-launch estimates (90 vs. 150 per
year), are the result of a threshold that is similar to that of BATSE. In view
of these inferences, afterglow observers may find it advisable to make
significant changes in follow up strategies of Swift events. [abridged]


title: Can a photometric redshift code reliably determine dust extinction?

abstract:
  Photometric redshifts can be routinely obtained to accuracies of better than
0.1 in Delta(z)/(1+z). However, the issue of dust extinction is one that has
still not been well quantified. In this paper the success of two
template-fitting photometric redshift codes (IMPZ and HYPERZ) at reliably
returning Av in addition to redshift is explored. New data on the CNOC2
spectroscopic sample of 0.2<z<0.7 galaxies are presented. These data allow us
to estimate Av values from the observed Balmer decrements. We also investigate
whether the empirical value of gamma=0.44, the ratio between gas- and star-
derived extinction, as determined by Calzetti (2001), is necessarily the best
value for this sample.
  When comparing the two codes to the Balmer-derived Av, a correlation between
the photometrically derived Av, Phot-Av, and the Balmer-Av is found. The
correlation is improved when the empirical value of gamma=0.44 is allowed to
vary. From least-squares-fitting the minimum in the reduced chi^2 distribution
is found for gamma~0.25 +/- 0.2. For the sample of galaxies here, the factor of
two difference in covering factor implied by the Calzetti ratio is found to be
plausible. The CNOC2 galaxies with detected Balmer lines have some preference
for an increased covering factor difference, which would perhaps imply they are
undergoing more rapid, `bursty' star formation than the galaxies Calzetti used
in her derivation.


title:
Eclipsing binaries in the Galactic Bulge: candidates for distance
  estimates

abstract:
  The 222~000 I-band light curves of variable stars detected by the OGLE-II
survey in the direction of the Galactic Bulge have been searched for eclipsing
binaries (EBs). A previously developed code to analyze lightcurve shapes and
identify long period variables (LPVs) has been adapted to identify EBs. The
parameters in the modified code have been optimised to recover a list of about
140 detached EBs in the Small Magellanic Cloud previously identified in the
literature as particularly well suited for distance estimates (and wich have
periods \more 0.85 days). The power of the code is demonstrated by identifying
16 and 178 previously uncatalogued EBs in the SMC and LMC, respectively. Among
the 222~000 variable stars in the direction of the Galactic Bulge 3053 EBs have
been identified. Periods and phased lightcurves are presented.


title:
The Redshift Distribution of Distant Supernovae and its Use in Probing
  Reionization

abstract:
  We model the number of detectable supernovae (SNe) as a function of redshift
at different flux thresholds, making use of the observed properties of local
SNe, such as their lightcurves, fiducial spectra, and peak magnitude
distributions. We obtain a rate of 0.4-2.3 SNe/arcmin^2/yr at z > 5 at the near
infrared (4.5 micron) flux density threshold of 3 nJy (achievable with the
James Webb Space Telescope (JWST) in a 10^5 s integration). In a hypothetical
one-year survey, it should be possible to detect up to several thousand SNe per
unit redshift at z > 6. We discuss the possible application of such a large
sample of distant SNe as a probe of the epoch of reionization. By heating the
intergalactic medium and raising the cosmological Jeans mass, the process of
reionization can suppress star formation in low-mass galaxies. This could have
produced a relatively sharp drop in the SNR around the redshift of
reionization. We quantify the detectability of this feature in future surveys
of distant SNe by varying the redshift and duration of the feature, as well as
its impact on the SFR in low-mass halos, which results in different redshifts,
widths, and sizes of the drop in the expected SFR. We find that the drop can be
detected out to z_re ~ 13, as long as (i) the reionization history contains a
relatively rapid feature which is synchronized over different regions to within
\Delta z < 1 - 3, (ii) the star-formation efficiency in halos that dominate
reionization is ~ 10%, and (iii) reionization significantly suppresses the star
formation in low-mass halos. Depending on the details of (i) - (iii), this
could be achieved with a survey lasting less than two weeks. Detecting this
signature would also help elucidate the feedback mechanism that regulates
reionization.


title: Absorption Systems In Radio-Selected QSO Surveys

abstract:
  Radio-selected samples of quasars with complete optical identifications offer
an ideal dataset with which to investigate dust bias associated with
intervening absorption systems. Here, we review our work on the Complete
Optical and Radio Absorption Line System (CORALS) survey whose aim is to
quantify this bias and assess the impact of dust on absorber statistics. First,
we review previously published results on the number density and gas content of
high column density absorbers over the redshift range 0.6 < z < 3.5. We then
present the latest results from CORALS which focus on measuring the metal
content of our unbiased absorber sample and an investigation of their
optical--IR colours. Overall we find that although dust is unarguably present
in absorption galaxies, the level appears to be low enough that the statistics
of previous magnitude limited samples have not been severely affected and that
the subsequent reddening of background QSOs is small.


title:
Dust Scattering in Miras R Car and RR Sco resolved by optical
  interferometric polarimetry

abstract:
  We present optical interferometric polarimetry measurements of the Mira-like
variables R Car and RR Sco, using the Sydney University Stellar Interferometer.
By making visibility measurements in two perpendicular polarisations, the
relatively low-surface brightness light scattered by atmospheric dust could be
spatially separated from the bright Mira photospheric flux. This is the first
reported successful use of long-baseline optical interferometric polarimetry.
Observations were able to place constraints on the distribution of
circumstellar material in R Car and RR Sco. The inner radius of dust formation
for both stars was found to be less than 3 stellar radii: much closer than the
expected innermost stable location for commonly-assumed astrophysical ``dirty
silicate'' dust in these systems (silicate dust with a significant iron
content). A model with the dust distributed over a shell which is geometrically
thin compared to the stellar radius was preferred over an outflow. We propose
dust components whose chemistry and opacity properties enable survival at these
extreme inner radii.


title:
The Influence of the Magnetic Field on the Properties of Neutron Star
  Matter

abstract:
  In the mean field approximation of the relativistic $\sigma$-$\omega$-$\rho$
model, the magnetic fields are incorporated, and its influence on the
properties of n-p-e neutron star matter are studied. When the strength of the
magnetic field is weaker than $\sim 10^{18}$G, the particle fractions and
chemical potentials, matter energy density and pressure hardly change with the
magnetic field; when the strength of the magnetic field is stronger than $\sim
10^{20}$G, the above quantities change with the magnetic field evidently.
Furthermore, the pressure is studied in both thermodynamics and hydrodynamics.
The difference between these two ways exits in the high density region, that
is, the thermal self-consistency may not be satisfied in this region if the
magnetic field is considered.


title:
Large-Scale Sidereal Anisotropy of Galactic Cosmic-Ray Intensity
  Observed by the Tibet Air Shower Array

abstract:
  We present the large-scale sidereal anisotropy ofgalactic cosmic-ray
intensity in the multi-TeV region observed with the Tibet-IIIair shower array
during the period from 1999 through 2003. The sidereal daily variation of
cosmic rays observed in this experiment shows an excess of relative intensity
around $4\sim7 $ hours local sidereal time, as well as a deficit around 12
hours local sidereal time. While the amplitude of the excess is not significant
when averaged over all declinations, the excess in individual declinaton bands
becomes larger and clearer as the viewing direction moves toward the south. The
maximum phase of the excess intensity changes from $\sim$7 at the northern
hemisphere to $\sim$4 hours at the equatorial region. We also show that both
the amplitude and the phase of the first harmonic vector of the daily variation
are remarkably independent of primary energy in the multi-TeV region. This is
the first result determining the energy and declination dependences of the full
24-hour profiles of the sidereal daily variation in the multi-TeV region with a
single air shower experiment.


title:
A Measurement of the Quadrupole Power Spectrum in the Clustering of the
  2dF QSO Survey

abstract:
  We report a measurement of the quadrupole power spectrum in the two degree
field (2dF) QSO redshift (2QZ) survey. The analysis uses an algorithm parallel
to that for the estimation of the standard monopole power spectrum without
first requiring computation of the correlation function or the anisotropic
power spectrum. The error on the quadrupole spectrum is rather large but the
best fit value of the bias parameter from the quadrupole spectrum is consistent
with that from previous investigations of the 2dF data.


title:
Modulation of a Chirp Gravitational Wave from a Compact Binary due to
  Gravitational Lensing

abstract:
  A possible wave effect in the gravitational lensing phenomenon is discussed.
We consider the interference of two coherent gravitational waves of slightly
different frequencies from a compact binary, due to the gravitational lensing
by a galaxy halo. This system shows the modulation of the wave amplitude. The
lensing probability of such the phenomenon is of order 10^{-5} for a high-z
source, but it may be advantageous to the observation due to the magnification
of the amplitude.


title: The XMM-LSS survey: The XMDS/VVDS 4 sigma catalogue

abstract:
  We present a first catalogue of X-ray sources resulting from the central area
of the XMM-LSS (Large Scale Structure survey). We describe the reduction
procedures and the database tools we developed and used to derive a well
defined catalogue of X-ray sources. The present catalogue is limited to a
sub-sample of 286 sources detected at 4 sigma in the 1 deg^2 area covered by
the photometric VVDS (VIRMOS VLT Deep Survey), which allows us to provide
optical and radio identifications. We also discuss the X-ray properties of a
larger X-ray sample of 536 sources detected at > 4 sigma in the full 3 deg^2
area of the XMM Medium Deep Survey (XMDS) independently of the optical
identification. We also derive the logN-logS relationship for a sample of more
than one thousand sources that we discuss in the context of other surveys at
similar fluxes.


title: Chemical abundances in 43 metal-poor stars

abstract:
  We have derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni
and Ba for 43 metal-poor field stars in the solar neighbourhood with iron
abundances [Fe/H] ranging from -0.4 to -3.0. Total abundance errors are
estimated to about 0.1-0.2 dex for most elements, while relative abundances are
most probably more accurate. We have made an extensive comparison with other
similar studies and traced the reasons for the, in most cases, relatively small
differences.
  Among the results we note the following: We find [O/Fe] from the O I IR-
triplet lines to possibly increase beyond [Fe/H]=-1.0, though considerably less
than obtained by others from abundances based on OH lines. We find correlations
among the deviations for individual stars from the trends of individual alpha
elements relative to Fe. This may support the idea that the formation of the
Halo stars occurred in smaller systems with different star formation rates. We
verify the finding by Gratton et al. (2003b) that stars that do not participate
in the rotation of the galactic disk show a lower mean and larger spread in
[alpha/Fe] than stars participating in the general rotation. The latter stars
also seem to show some correlation between [alpha/Fe] and rotation speed. We
finally advocate that a spectroscopic study of a larger sample of halo stars
with well-defined selection criteria is very important, in addition to the very
considerable efforts that various groups have already made. (Abridged)


title:
The Las Campanas Infra-red Survey. V. Keck Spectroscopy of a large
  sample of Extremely Red Objects

abstract:
  (Abridged) We present deep Keck spectroscopy, using the DEIMOS and LRIS
spectrographs, of a large and representative sample of 67 ``Extremely Red
Objects'' (EROs) to H=20.5, with I-H>3.0, in three of the Las Campanas Infrared
Survey fields. Spectroscopic redshifts are determined for 44 sources, of which
only two are contaminating low mass stars. When allowance is made for
incompleteness, the spectroscopic redshift distribution closely matches that
predicted earlier on the basis of photometric data. Our spectra are of
sufficient quality that we can address the important question of the nature and
homogeneity of the z>0.8 ERO population. A dominant old stellar population is
inferred for 75% of our spectroscopic sample; a higher fraction than that seen
in smaller, less-complete samples with broader photometric selection criteria
(e.g. R-K). However, only 28% have spectra with no evidence of recent star
formation activity, such as would be expected for a strictly passively-evolving
population. More than ~30% of our absorption line spectra are of the `E+A' type
with prominent Balmer absorption consistent, on average, with mass growth of
5-15% in the past Gyr. We use our spectroscopic redshifts to improve earlier
estimates of the spatial clustering of this population as well as to understand
the significant field-to-field variation. Our spectroscopy enables us to
pinpoint a filamentary structure at z=1.22 in the Chandra Deep Field South.
Overall, our study suggests that the bulk of the ERO population is an
established population of clustered massive galaxies undergoing intermittent
activity consistent with continued growth over the redshift interval 0.8<z<1.6.


title:
Chandra observations of the millisecond X-ray pulsar IGR J00291+5934 in
  quiescence

abstract:
  In this Paper we report on our analysis of three Chandra observations of the
accretion-powered millisecond X-ray pulsar IGR J00291+5934 obtained during the
late stages of the 2004 outburst. We also report the serendipitous detection of
the source in quiescence by ROSAT during MJD 48830-48839. The detected 0.3-10
keV source count rates varied significantly between the Chandra observations
from (7.2+-1.2)x10^-3, (6.8+-0.9)x10^-3, and (1.4+-0.1)x10^-2 counts per second
for the 1st, 2nd, and 3rd Chandra observation, on MJD 53371.88, 53383.99, and
53407.57, respectively. The count rate for the 3rd observation is 2.0+-0.4
times as high as that of the average of the first two observations. The
unabsorbed 0.5-10 keV source flux for the best-fit power-law model to the
source spectrum was (7.9+-2.5)x10^-14, (7.3+-2.0)x10^-14, and
(1.17+-0.22)x10^-13 erg cm^-2 s^-1 for the 1st, 2nd, and 3rd Chandra
observation, respectively. We find that this source flux is consistent with
that found by ROSAT [~(5.4+-2.4)x10^-14 erg cm^-2 s^-1]. Under the assumption
that the interstellar extinction, N_H, does not vary between the observations,
we find that the blackbody temperature during the 2nd Chandra observation is
significantly higher than that during the 1st and 3rd observation. Furthermore,
the effective temperature of the neutron star derived from fitting an absorbed
blackbody or neutron star atmosphere model to the data is rather high in
comparison with many other neutron star soft X-ray transients in quiescence,
even during the 1st and 3rd observation. If we assume that the source quiescent
luminosity is similar to that measured for two other accretion powered
millisecond pulsars in quiescence, the distance to IGR J00291+5934 is 2.6-3.6
kpc.


title: Acceleration of the universe with a simple trigonometric potential

abstract:
  In this paper we investigate the quintessence model with a minimally coupled
scalar field in the context of recent supernovae observations. By choosing a
particular form of the deceleration parameter q, which gives an early
deceleration and late time acceleration for dust dominated model, we show that
this sign flip in q can be obtained by a simple trigonometric patential. The
early matter dominated model expands with q=1/2 as desired and enters a
negative q phase quite late during the evolution.


title:
The Connection Between Galaxies and Intergalactic Absorption Lines at
  Redshift 2<z<3

abstract:
  Absorption-line spectroscopy of 23 background QSOs and numerous background
galaxies has let us measure the spatial distribution of metals and neutral
hydrogen around 1044 UV-selected galaxies at redshifts 1.8<z<3.3. The typical
galaxy is surrounded to radii r~40 proper kpc by gas that has a large velocity
spread (dv>260 km/s) and produces very strong absorption lines (N_CIV >> 10^14
cm^-2) in the spectra of background objects. Absorption with an average column
density of N_CIV ~ 10^14 cm^-2 extends to 80 kpc, a radius large enough to
imply that most strong intergalactic CIV absorption is associated with
star-forming galaxies like those in our sample. We find that the galaxy-CIV
cross-correlation length increases with CIV column density and is similar to
the galaxy-galaxy length (r_0 ~ 4 h^-1 Mpc) for N_CIV > 10^12.5 cm^-2.
Distortions in the redshift-space galaxy-CIV correlation function on small
scales may imply that some of the CIV systems have large peculiar velocities.
Four of the five detected OVI absorption systems in our sample lie within 400
proper kpc of a known galaxy. Strong Lyman-a absorption is produced by the
intergalactic gas within 1 h^-1 comoving Mpc of most galaxies, but for a
significant minority (~1/3) the absorption is weak or absent. We were unable to
identify any statistically significant differences between galaxies with weak
nearby HI absorption and the rest, although galaxies with weak absorption may
have higher star-formation rates. Galaxies near intergalactic CIV systems
appear to reside in relatively dense environments and to have distinctive
spectral energy distributions that are characterized by blue colors and young
ages. (abridged)


title:
The CFHT Legacy Survey: The Morphology-Density Relation of Galaxies out
  to Z~1

abstract:
  We study the relationships between galaxy total luminosity (M_g), morphology,
color and environment as a function of redshift. We use a magnitude-limited
sample of 65,624 galaxies in the redshift range 0<z<1.3 taken from one of the
Canada-France-Hawaii Telescope Legacy Survey Deep Fields. We parametrize galaxy
morphology according to the Sersic index n. Our n>2 number fractions at z=0.1
agree well with those based on SDSS galaxies. We find that the n>2 galaxy
number fraction is constant with redshift in the field. However, for overdense
environments this fraction is larger and increases towards lower redshifts,
higher densities and higher luminosities. Rest-frame color-magnitude diagrams
show that the color distribution is bimodal out to our redshift limit of z~1
with a prominent red-sequence of galaxies at 0.2<z<0.4 and a large blue-peak
dominance at 0.8<z<1. We use this bimodality to define a red galaxy fraction
(rest-frame u-g>1). For all environments, this fraction increases towards lower
redshifts and higher luminosities. The red fraction within cluster-like regions
changes 60% faster with redshift as compared to the field for M_g<-19.5. Using,
for the first time, observations across many cluster-field interfaces
distributed over a single, large volume, we trace the large-scale
morphology-density relation and the Butcher-Oemler effect over a period of
almost 8 Gyr.