title: Detection of a non-Gaussian Spot in WMAP

abstract:
  An extremely cold and big spot in the WMAP 1-year data is analyzed. Our work
is a continuation of a previous paper (Vielva et al. 2004) where
non-Gaussianity was detected, with a method based on the Spherical Mexican Hat
Wavelet (SMHW) technique. We study the spots at different thresholds on the
SMHW coefficient maps, considering six estimators, namely number of maxima,
number of minima, number of hot and cold spots, and number of pixels of the
spots. At SMHW scales around 4 degrees (10 degrees on the sky), the data
deviate from Gaussianity. The analysis is performed on all sky, the northern
and southern hemispheres, and on four regions covering all the sky. A cold spot
at (b = -57, l = 209) is found to be the source of this non-Gaussian signature.
We compare the spots of our data with 10000 Gaussian simulations, and conclude
that only around 0.2% of them present such a cold spot. Excluding this spot,
the remaining map is compatible with Gaussianity and even the excess of
kurtosis in Vielva et al. 2004, is found to be due exclusively to this spot.
Finally, we study whether the spot causing the observed deviation from
Gaussianity could be generated by systematics or foregrounds. None of them seem
to be responsible for the non-Gaussian detection.


title: WARP liquid argon detector for dark matter survey

abstract:
  The WARP programme is a graded programme intended to search for cold Dark
Matter in the form of WIMP's. These particles may produce via weak interactions
nuclear recoils in the energy range 10-100 keV. A cryogenic noble liquid like
argon, already used in the realization of very large detector, permits the
simultaneous detection of both ionisation and scintillation induced by an
interaction, suggesting the possibility of discriminating between nuclear
recoils and electrons mediated events. A 2.3 litres two-phase argon detector
prototype has been used to perform several tests on the proposed technique.
Next step is the construction of a 100 litres sensitive volume device with
potential sensitivity a factor 100 better than presently existing experiments.


title: The Radiometric Bode's Law and Extrasolar Planets

abstract:
  We predict the radio flux densities of the extrasolar planets in the current
census, making use of an empirical relation--the radiometric Bode's
Law--determined from the five ``magnetic'' planets in the solar system (Earth
and the four gas giants). Radio emission from these planets results from
solar-wind powered electron currents depositing energy in the magnetic polar
regions. We find that most of the known extrasolar planets should emit in the
frequency range 10--1000 MHz and, under favorable circumstances, have typical
flux densities as large as 1 mJy. We also describe an initial, systematic
effort to search for radio emission in low radio frequency images acquired with
the Very Large Array. The limits set by the VLA images (~ 300 mJy) are
consistent with, but do not provide strong constraints on, the predictions of
the model. Future radio telescopes, such as the Low Frequency Array (LOFAR) and
the Square Kilometer Array (SKA), should be able to detect the known extrasolar
planets or place austere limits on their radio emission. Planets with masses
much lower than those in the current census will probably radiate below 10 MHz
and will require a space-based array.


title:
Mid- and Far-Infrared ISO Limits on Dust Disks around Millisecond
  Pulsars

abstract:
  We report 60 and 90 micron observations of 7 millisecond pulsars with ISO.
The pulsar PSR B1257+12 is orbited by three planets, and other millisecond
pulsars may be orbited by dust disks that represent planets that failed to form
or their residue. We do not detect any infrared emission from the 7 pulsars in
our sample, and typical upper limits are 100 mJy. Using a simple model, we
constrain the typical dust disk mass to be less than of order 100 M_Earth,
assuming that the heating of any putative dust disk would be coupled only
weakly to the pulsar's emission. If the planets around PSR B1257+12 are
composed largely of metals, our limits are probably an order of magnitude above
plausible values for the disk mass in metals. Future observations with the
Spitzer Space Telescope should be capable of probing into the range of disk
masses that could plausibly give rise to planets.


title: A Free-Electron Laser in the Pulsar Magnetosphere

abstract:
  We have studied systematically the free-electron laser in the context of high
brightness pulsar radio emission. In this paper, we have numerically examined
the case where a transverse electromagnetic wave is distorting the motion of a
relativistic electron beam while travelling over one stellar radius ($ approx
10 :{km}$). For different sets of parameters, coherent emission is generated by
bunches of beam electrons in the radio domain, with bandwidths of 3 GHz. Pulse
power often reached $10^{13} :{W}$, which corresponds with brightness
temperature of $10^{30} :{K}$. The duration of these pulses is of the order of
nanoseconds. In the context of pulsar radio emission, our results indicate that
the laser can produce elementary bursts of radiation which build up the
observed microstructures of a few tens of microseconds duration. The process is
sensitive mostly to the beam particles energy, number density and the
background magnetic field, but much less so to the transverse wave parameters.
We demonstrate that the operation of a free-electron laser with a transverse
electromagnetic wiggler in the pulsar magnetosphere occurs preferably at moder
ate Lorentz factors $ gamma geq 100$, high beam density $n gtrsim 0.1
n_{textrm{GJ}}(r_ ast)$ where $n_{textrm{GJ}}(r_ ast)$ is the Goldrei ch-Julian
density at a stellar radius $r_ ast$, and finally, at large altitude where the
background magnetic field is low $B_0 leq 10^{-2} textrm{T}$.


title:
Dense gas in nearby galaxies XVI. The nuclear starburst environment in
  NGC4945

abstract:
  A multi-line millimeter-wave study of the nearby starburst galaxy NGC 4945
has been carried out using the Swedish-ESO Submillimeter Telescope (SEST). The
study covers the frequency range from 82 GHz to 354 GHz and includes 80
transitions of 19 molecules. 1.3 mm continuum data of the nuclear source are
also presented. A large number of molecular species indicate the presence of a
prominent high density interstellar gas component characterized by $n_{\rm
H_2}\sim10^5$ cm$^{-3}$. Abundances of molecular species are calculated and
compared with abundances observed toward the starburst galaxies NGC 253 and M
82 and galactic sources. Apparent is an `overabundance' of HNC in the nuclear
environment of NGC 4945. While the HNC/HCN $J$=1--0 line intensity ratio is
$\sim$0.5, the HNC/HCN abundance ratio is $\sim$1. While HCN is subthermally
excited ($T_{\rm ex}\sim$8 K), CN is even less excited ($T_{\rm ex}\sim$3--4
K), indicating that it arises from a less dense gas component and that its
$N$=2--1 line can be optically thin even though its $N$=1--0 emission is
moderately optically thick. Overall, fractional abundances of NGC 4945 suggest
that the starburst has reached a stage of evolution that is intermediate
between those observed in NGC 253 and M 82. Carbon, nitrogen, oxygen and sulfur
isotope ratios are also determined. Within the limits of uncertainty, carbon
and oxygen isotope ratios appear to be the same in the nuclear regions of NGC
4945 and NGC 253. High $^{18}$O/$^{17}$O, low $^{16}$O/$^{18}$O and
$^{14}$N/$^{15}$N and perhaps also low $^{32}$S/$^{34}$S ratios appear to be
characteristic properties of a starburst environment in which massive stars
have had sufficient time to affect the isotopic composition of the surrounding
interstellar medium.


title:
Cosmological gamma ray and neutrino backgrounds due to neutralino dark
  matter annihilation

abstract:
  We compute the cosmological background radiation of gamma rays and neutrinos
due to neutralino annihilation in evolving dark matter halos, assuming the
observed dark matter is comprised of thermally excited neutralinos in the MSSM.
The spectrum of this gamma-ray background radiation does not show strong
annihilation line features, but could amount to a significant fraction of the
extragalactic gamma ray continuum flux observed by EGRET above a few GeV. The
corresponding cosmological neutrino background is weak compared to the
atmospheric foreground. Assuming full mixing, however, the cosmological
tau-neutrino background could be detectable with a flavor-discriminating
neutrino telescope in the energy range 10 GeV - 1 TeV. A small anisotropy of
the background radiation is expected, reflecting the local clustering of dark
matter halos along the supergalactic plane.


title: The Origin of Massive O-type Field Stars. Part I: A Search for Clusters

abstract:
  We present a study aimed at clarifying the birthplace for 43 massive O-type
field stars. In this first paper we present the observational part: a search
for stellar clusters near the target stars. We derive stellar density maps at
two different resolving scales, viz. 0.25pc and 1.0pc from NTT and TNG imaging
and the 2MASS catalogue. These scales are typical for cluster sizes. The main
result is that the large majority of the O-type field population are isolated
stars: only 12% (5 out of 43) of the O-type field stars is found to harbour a
small-scale stellar cluster. We review the literature and aim at characterizing
the stellar field of each O-type field star with the emphasis on star formation
and the presence of known young stellar clusters. An analysis of the result of
this paper and a discussion of the O-type field population as products of a
dynamical ejection event is presented in an accompanying paper.


title: GRS 1915+105: The first three months with INTEGRAL

abstract:
  GRS 1915+105 is being observed as part of an Open Time monitoring program
with INTEGRAL. Three out of six observations from the monitoring program are
presented here, in addition to data obtained through an exchange with other
observers. We also present simultaneous RXTE observations of GRS 1915+105.
During INTEGRAL Revolution 48 (2003 March 6) the source was observed to be in a
highly variable state, characterized by 5-minute quasi-periodic oscillations.
During these oscillations, the rise is faster than the decline, and is harder.
This particular type of variability has never been observed before. During
subsequent INTEGRAL revolutions (2003 March-May), the source was in a steady or
''plateau'' state (also known as class $\chi$ according to Belloni et al.
2000). Here we discuss both the temporal and spectral characteristics of the
source during the first three months of observations. The source was clearly
detected with all three gamma-ray and X-ray instruments onboard INTEGRAL.


title: The kinematics of the bi-lobal supernova remnant G 65.3+5.7 - Paper II

abstract:
  Further deep, narrow-band images in the light of [O III] 5007 A have been
added to the previous mosaic of the faint galactic supernova remnant G
65.3+5.7. Additionally longslit spatially resolved [O III] 5007 A line profiles
have been obtained at sample positions using the Manchester Echelle
Spectrometer at the San Pedro Martir observatory. The remnant is shown to be
predominantly bi-lobal with an EW axis for this structure. However, a faint
additional northern lobe has now been revealed.
  Splitting of the profiles along the slit lengths, when extrapolated to the
remnant's centre, although uncertain suggests that the expansion velocity of
this remnant is between 124 and 187 km/s ie much lower than the 400 km/s
previously predicted for the forward shock velocity from the X-ray emission.
  An expansion proper motion measurement of 2.1+-0.4 arcsec in 48 years for the
remnant's filamentary edge in the light of Halpha+[N II] has also been made.
When combined with an expansion velocity of ~155 km/s, a distance of ~800 pc to
G 65.3+5.7 is derived.
  Several possibilities are considered for the large difference in the
expansion velocity measured here and the 400 km/s shock velocity required to
generate the X-ray emission. It is also suggested that the morphology of the
remnant may be created by a tilt in the galactic magnetic field in this
vicinity.


title: A Note on Gravitational Brownian Motion

abstract:
  Chandrasekhar's theory of stellar encounters predicts a dependence of the
Brownian motion of a massive particle on the velocity distribution of the
perturbing stars. One consequence is that the expectation value of the massive
object's kinetic energy can be different from that of the perturbers. This
effect is shown to be modest however, and substantially smaller than claimed in
a recent study based on a more approximate treatment of the encounter
equations.


title:
Classical and MgII-selected Damped Lyman-alpha Absorbers: impact on
  Omega_HI at z<1.7

abstract:
  The Damped Lyman-alpha systems (DLAs), seen in absorption in the spectrum of
quasars, are believed to contain a large fraction of the neutral gas in the
Universe. Paradoxically, these systems are more difficult to observe at
z_abs<1.7, since they are rare and their HI feature then falls in UV spectra.
Rao & Turnshek (2000) pioneered a method based on MgII-selected DLAs, that is
absorbers discovered thanks to our knowledge of their MgII feature in optical
spectra. We use new observations undertaken at the TNG as well as a careful
literature & archival search to build samples of low redshift absorbers
classified according to the technique used for their discovery. We successfully
recover N(HI) and equivalent widths of FeII 2600, MgII 2796, MgII 2803 and MgII
2852 for a sample of 36 absorbers, 21 of which are MgII-selected. We find that
the MgII-selected sample contains a marginally larger fraction of absorbers
with log N(HI)>21.0 than seen otherwise at low redshift. If confirmed, this
property will in turn affect estimates of Omega_HI which is dominated by the
highest HI column densities. We find that log N(HI) does not correlate
significantly with metal equivalent widths. Similarly, we find no evidence that
gravitational lensing, the fraction of associated systems or redshift evolution
affect the absorber samples in a different way. We conclude that the hint of
discrepancies in N(HI) distributions most likely arises from small number
statistics. Therefore, further observations are required to better clarify the
impact of this discrepancy on estimates of Omega_HI at low redshift.


title: The Phantom Bounce: A New Oscillating Cosmology

abstract:
  An oscillating universe cycles through a series of expansions and
contractions. We propose a model in which ``phantom'' energy with $p < -\rho$
grows rapidly and dominates the late-time expanding phase. The universe's
energy density is so large that the effects of quantum gravity are important at
both the beginning and the end of each expansion (or contraction). The bounce
can be caused by high energy modifications to the Friedmann equation, which
make the cosmology nonsingular. The classic black hole overproduction of
oscillating universes is resolved due to their destruction by the phantom
energy.


title:
High-Resolution Ultraviolet Spectra of the Dwarf Seyfert 1 Galaxy NGC
  4395: Evidence for Intrinsic Absorption

abstract:
  We present ultraviolet spectra of the dwarf Seyfert 1 nucleus of NGC 4395,
obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble
Space Telescope's Space Telescope Imaging Spectrograph at velocity resolutions
of 7 to 15 km/sec. We confirm our earlier claim of C IV absorption in
low-resolution UV spectra and detect a number of other absorption lines with
lower ionization potentials. In addition to the Galactic lines, we identify two
kinematic components of absorption that are likely to be intrinsic to NGC 4395.
We consider possible origins of the absorption, including the interstellar
medium (ISM) of NGC 4395, the narrow-line region (NLR), outflowing UV
absorbers, and X-ray ``warm absorbers.'' Component 1, at a radial velocity of
-770 km/sec with respect to the nucleus, is only identified in the C IV 1548.2
line. It most likely represents an outflowing UV absorber, similar to those
seen in a majority of Seyfert 1 galaxies, although additional observations are
needed to confirm the reality of this feature. Component 2, at -114 km/sec,
most likely arises in the ISM of NGC 4395; its ionic column densities cannot be
matched by photoionization models with a power-law continuum. Our models of the
highly ionized X-ray absorbers claimed for this active galactic nucleus
indicate that they would have undetectable C IV absorption, but large O VI and
H I columns should be present. We attribute our lack of detection of the O VI
and Ly-beta absorption from the X-ray absorbers to a combination of noise and
dilution of the nuclear spectrum by hot stars in the large FUSE aperture.


title:
Cosmic Star Formation, Reionization, and Constraints on Global Chemical
  Evolution

abstract:
  Motivated by the WMAP results indicating an early epoch of reionization, we
consider alternative cosmic star formation models which are capable of
reionizing the early intergalactic medium. We develop models which include an
early burst of massive stars (with several possible mass ranges) combined with
standard star formation. We compute the stellar ionizing flux of photons and we
track the nucleosynthetic yields for several elements: D, He4, C, N, O, Si, S,
Fe, Zn. We compute the subsequent chemical evolution as a function of redshift,
both in the intergalactic medium and in the interstellar medium of forming
galaxies, starting with the primordial objects which are responsible for the
reionization. We apply constraints from the observed abundances in the Lyman
alpha forest and in Damped Lyman alpha clouds in conjunction with the ability
of the models to produce the required degree of reionization. We also consider
possible constraints associated with the observations of the two extremely
metal-poor stars HE 0107-5240 and CS22949-037. We confirm that an early
top-heavy stellar component is required, as a standard star formation model is
unable to reionize the early Universe and reproduce the abundances of the very
metal-poor halo stars. A bimodal (or top-heavy) IMF (40 - 100 M_\odot) is our
preferred scenario compared to the extreme mass range (\ga 100 M_\odot) often
assumed to be responsible for the early stages of reionization. A mode of even
more extreme stellar masses in the range (\ge 270 M_\odot) has also been
considered. All massive stars in this mode collapse entirely into black holes,
and as a consequence, chemical evolution and reionization are de-correlated.
[Abstract abbreviated.]


title: The shape of non-Gaussianities

abstract:
  We study the dependence on configuration in momentum space of the primordial
3-point function of density perturbations in several different scenarios:
standard slow-roll inflation, curvaton and variable decay models, ghost
inflation, models with higher derivative operators and the DBI model of
inflation. We define a cosine between the distributions using a measure based
on the ability of experiments to distinguish between them. We find that models
fall into two broad categories with fairly orthogonal distributions. Models
where non-Gaussianity is created at horizon-crossing during inflation and
models in which the evolution outside the horizon dominates. In the first case
the 3-point function is largest for equilateral triangles, while in the second
the dominant contribution to the signal comes from the influence of long
wavelength modes on small wavelength ones. We show that, because the
distributions in these two cases are so different, translating constraints on
parameters of one model to those of another based on the normalization of the
3-point function for equilateral triangles can be very misleading.


title:
Mass-sheet degeneracy: Fundamental limit on the cluster mass
  reconstruction from statistical (weak) lensing

abstract:
  Weak gravitational lensing is considered to be one of the most powerful tools
to study the mass and the mass distribution of galaxy clusters. However, weak
lensing mass reconstructions are plagued by the so-called mass-sheet
degeneracy--the surface mass density \kappa of the cluster can be determined
only up to a degeneracy transformation \kappa \to \kappa' = \lambda \kappa + (1
-\lambda), where \lambda is an arbitrary constant. This transformation
fundamentally limits the accuracy of cluster mass determinations if no further
assumptions are made. We describe here a method to break the mass-sheet
degeneracy in weak lensing mass maps using distortion and redshift information
of background galaxies and illustrate this by two simple toy models. Compared
to other techniques proposed in the past, it does not rely on any assumptions
on cluster potential; it can be easily applied to non-parametric
mass-reconstructions and no assumptions on boundary conditions have to be made.
In addition it does not make use of weakly constrained information (such as the
source number counts, used in the magnification effect). Our simulations show
that we are effectively able to break the mass-sheet degeneracy for
supercritical lenses, but that for undercritical lenses the mass-sheet
degeneracy is very difficult to be broken, even under idealised conditions.


title:
Chandra's Discovery of Activity in the Quiescent Nuclear Black Hole of
  NGC 821

abstract:
  We report the results of the {\it Chandra} ACIS-S observations of the
elliptical galaxy NGC 821, which harbors a supermassive nuclear black hole (of
$3.5 \times 10^7 M_{\odot}$), but does not show sign of AGN activity. A small,
8.5$^{\prime\prime}$ long ($\sim 1$ kpc at the galaxy's distance of 23 Mpc),
S-shaped, jet-like feature centered on the nucleus is detected in the 38 ksec
ACIS-S integrated exposure of this region. The luminosity of this feature is
$L_X \sim 2.6 \times 10^{39} \rm ergs s^{-1}$ (0.3-10 keV), and its spectrum is
hard (described by a power-law of $\Gamma = 1.8^{+0.7}_{-0.6}$; or by thermal
emission with $kT >2$ keV). We discuss two possibilities for the origin of this
feature: (1) a low-luminosity X-ray jet, or (2) a hot shocked gas. In either
case, it is a clear indication of nuclear activity, detectable only in the
X-ray band. Steady spherical accretion of the mass losses from the central
stellar cusp within the accretion radius, when coupled to a high radiative
efficiency, already provides a power source exceeding the observed radiative
losses from the nuclear region.


title: Radio Emission from AGN detected by the VLA FIRST Survey

abstract:
  Using the most recent (April 2003) version of the VLA FIRST survey radio
catalog, we have searched for radio emission from $>2800$ AGN taken from the
most recent (2001) version of the Veron-Cetty and Veron AGN catalog. These AGN
lie in the ~9033 square degrees of sky already covered by the VLA FIRST survey.
Our work has resulted in positive detection of radio emission from 775 AGN of
which 214 are new detections at radio wavelengths.


title:
Spectral Index and Quasi-Periodic Oscillation Frequency Correlation in
  Black Hole (BH) Sources: Observational Evidence of Two Phases and Phase
  Transition in BHs

abstract:
  Recent studies have shown that strong correlations are observed between the
low frequencies (1-10 Hz) of quasiperiodic oscillations (QPOs) and the spectral
power law index of several Black Hole (BH) candidate sources, in low hard
state, steep power-law (soft) state and in transition between these states. We
provide a model, that identifies and explains the origin of the QPOs and how
they are imprinted on the properties of power-law flux component. We argue the
existence of a bounded compact coronal region which is a natural consequence of
the adjustment of Keplerian disk flow to the innermost sub-Keplerian boundary
conditions near the central object and that ultimately leads to the formation
of a transition layer (TL) between the adjustment radius and the innermost
boundary. The model predicts two phases or states dictated by the photon
upscattering produced in the TL: (1) hard state, in which the TL is optically
thin and very hot (kT ~ 50 keV) producing photon upscattering via thermal
Componization; the photon spectrum index Gamma~1.7 for this state is dictated
by gravitational energy release and Compton cooling in an optically thin shock
near the adjustment radius; (2) a soft state which is optically thick and
relatively cold (kT~5 keV); the index for this state, Gamma~2.8 is determined
by soft-photon upscattering and photon trapping in converging flow into BH.


title:
A 1200 micron MAMBO Survey of ELAIS N2 and the Lockman Hole: I. Maps,
  sources and number counts

abstract:
  We present a deep, new 1200 micron survey of the ELAIS N2 and Lockman Hole
fields using the Max Planck Millimeter Bolometer array (MAMBO). The areas
surveyed are 160 arcmin^2 in ELAIS N2 and 197 arcmin^2 in the Lockman Hole,
covering the entire SCUBA `8 mJy Survey'. In total, 27 (44) sources have been
detected at a significance >=4.0sigma (>=3.5sigma). We present the 1200 micron
number counts and find evidence of a fall at bright flux levels. Employing
parametric models for the evolution of the local 60 micron IRAS luminosity
function (LF), we are able to account simultaneously for the 1200 and 850
micron counts, suggesting that the MAMBO and SCUBA sources trace the same
underlying population of high-redshift, dust-enshrouded galaxies. From a
nearest-neighbour clustering analysis we find tentative evidence that the most
significant MAMBO sources come in pairs, typically separated by ~23". Our MAMBO
observations unambiguously confirm around half of the SCUBA sources. In a
robust sub-sample of 13 SMGs detected by both MAMBO and SCUBA at a significance
>=3.5sigma, only one has no radio counterpart. Furthermore, the distribution of
850/1200 micron flux density ratios for this sub-sample is consistent with the
spectroscopic redshift distribution of radio-detected SMGs (Chapman et al.
2003). Finally, we have searched for evidence of a high-redshift tail of SMGs
amongst the 18 MAMBO sources which are not detected by SCUBA. While we cannot
rule out that some of them are SCUBA drop-outs at z >> 3, their overall
850-to-1200 micron flux distribution is statistically indistinguishable from
that of the 13 SMGS which were robustly identified by both MAMBO and SCUBA.


title:
Reconciling the positive DAMA annual modulation signal with the negative
  results of the CDMS II experiment

abstract:
  We examine the recent CDMS II results in the context of the mirror matter
interpretation of the DAMA/NaI experiment.We find that the favoured mirror
matter interpretation of the DAMA/NaI experiment -- a $He'/H'$ dominated halo
with a small $O'$ component is fully consistent with the null results reported
by CDMS II. While the CDMS II experiment is quite sensitive to a heavy $Fe'$
component, and may yet find a positive result, a more decisive test of mirror
matter-type dark matter would require a lower threshold experiment using light
target elements.


title:
X-ray Study of the Dark Matter Distribution in Clusters of Galaxies with
  Chandra

abstract:
  We study the total gravitating mass distribution in the central region of 23
clusters of galaxies with Chandra. Using a new deprojection technique, we
measure the temperature and gas density in the very central region of the
clusters as a function of radius without assuming any particular models. Under
the assumptions of hydrostatic equilibrium and spherical symmetry, we obtain
the deprojected mass profiles of these clusters.
  The mass profiles are nicely scalable with a characteristic radius
($r_{200}$) and mass ($M_{200}$) on the large scale of $r>0.1r_{200}$. In
contrast, the central ($r<0.1r_{200}$) mass profiles have a large scatter even
after the scaling. The inner slope $\alpha$ of the total mass density profile
($\rho(r) \propto r^{-\alpha}$) is derived from the slope of the integrated
mass profile. The values of the inner slope $\alpha$ at the radius of
$0.02r_{200}$ ($\alpha_0$) span a wide range from 0 to 1.2. For 6 out of 20
clusters, $\alpha_0$ is lower than unity at a 90 % confidence level. CDM
simulations predict that the inner slope $\alpha$ is in the range $1<\alpha<2$,
which is inconsistent with our results. We also found that the gas fraction
near the center of a cluster has a negative correlation with $\alpha_0$. Our
result suggests that the gas-rich clusters in the central region tend to have a
flat core.


title:
The Parkes multibeam pulsar survey: IV. Discovery of 180 pulsars and
  parameters for 281 previously known pulsars

abstract:
  The Parkes multibeam pulsar survey has led to the discovery of more than 700
pulsars. In this paper, we provide timing solutions, flux densities and pulse
profiles for 180 of these new discoveries. Two pulsars, PSRs J1736-2843 and
J1847-0130 have rotational periods P > 6s and are therefore among the slowest
rotating radio pulsars known. Conversely, with P = 1.8ms, PSR J1843-1113 has
the third shortest period of pulsars currently known. This pulsar and PSR
J1905+0400 (P = 3.8ms) are both solitary. We also provide orbital parameters
for a new binary system, PSR J1420-5625, which has P = 34ms, an orbital period
of 40 days and a minimum companion mass of 0.4 solar masses. The 10 degree-wide
strip along the Galactic plane that was surveyed is known to contain 264 radio
pulsars that were discovered prior to the multibeam pulsar survey. We have
redetected almost all of these pulsars and provide new dispersion measure
values and flux densities at 20cm for the redetected pulsars.


title:
Measuring cluster peculiar velocities with the Sunyaev-Zeldovich
  effects: scaling relations and systematics

abstract:
  The fluctuations in the Cosmic Microwave Background (CMB) intensity due to
the Sunyaev-Zeldovich (SZ) effect are the sum of a thermal and a kinetic
contribution. Separating the two components to measure the peculiar velocity of
galaxy clusters requires radio and microwave observations at three or more
frequencies, and knowledge of the temperature T_e of the intracluster medium
weighted by the electron number density. To quantify the systematics of this
procedure, we extract a sample of 117 massive clusters at redshift z=0 from an
N-body hydrodynamical simulation, with 2x480^3 particles, of a cosmological
volume 192 Mpc/h on a side of a flat Cold Dark Matter model with Omega_0=0.3
and Lambda=0.7. Our simulation includes radiative cooling, star formation and
the effect of feedback and galactic winds from supernovae. We find that (1) our
simulated clusters reproduce the observed scaling relations between X-ray and
SZ properties; (2) bulk flows internal to the intracluster medium affect the
velocity estimate by less than 200 km/s in 93 per cent of the cases; (3) using
the X-ray emission weighted temperature, as an estimate of T_e, can
overestimate the peculiar velocity by 20-50 per cent, if the microwave
observations do not spatially resolve the cluster. For spatially resolved
clusters, the assumptions on the spatial distribution of the ICM, required to
separate the two SZ components, still produce a velocity overestimate of 10-20
per cent, even with an unbiased measure of T_e. Thanks to the large size of our
cluster samples, these results set a robust lower limit of 200 km/s to the
systematic errors that will affect upcoming measures of cluster peculiar
velocities with the SZ effect.


title:
Active Galactic Nuclei. VII. The Spacecraft Wobble and X-Ray Variability
  of Seyfert Galaxy NGC 5548

abstract:
  In discussing the short-time variability of extragalactic X-ray sources, we
focus on explaining how wavelet transform in conjunction with non-linear
filtering methods are used to remove Poisson statistics and wobble-related
variability from the data. This enables the resolution of their intrinsic
stochastic, quasi-periodic and deterministic variable components, as well the
determination of their persistence. As detailed examples we review and extend
the application of these techniques to ROSAT data for the Seyfert I galaxy NGC
5548 and for the QSO 3C273. Besides illustrating the discriminating power of
these methods, these treatments confirm the intrinsic character of the
transient quasi-periodic and deterministic events in NGC 5548 and 3C273 and
enable us to compare both the elementary events and the short-time variability
in the two types of sources. These methods can be applied in the investigation
of intrinsic source variability in other spectral regions.


title: BVR photometry of the resolved dwarf galaxy Ho IX

abstract:
  We present BVR CCD photometry down to limiting magnitude B=23.5 mag for 232
starlike objects and 11 diffuse objects in a 5.4' x 5.4' field of Ho IX. The
galaxy is a gas-rich irregular dwarf galaxy possibly very close to M 81, which
makes it especially interesting in the context of the evolution of satellite
galaxies and the accretion of dwarf galaxies. Investigations of Ho IX were
hampered by relatively large contradictions in the magnitude scale between
earlier studies. With our new photometry we resolved these discrepancies. The
color magnitude diagram (CMD) of Ho IX is fairly typical of a star-forming
dwarf irregular, consistent with earlier results. Distance estimates from our
new CMD are consistent with Ho IX being very close to M 81 and therefore being
a definite member of the M 81 group, apparently in very close physical
proximity to M 81.


title: The power-law expansion universe and dark energy evolution

abstract:
  In order to depict the transition from deceleration to acceleration expansion
of the universe we use a power-law expansion scale factor, $a\sim
t^{n_0+bt^m}$, with $n_0$, $b$ and $m$ three parameters determined by $H_0$,
$q_0$ and $z_T$. For the spatially flat, isotropic and homogeneous universe,
such a scale factor leads to the results that the dark energy density is slowly
changing currently, and predicts the equation of state $w_X$ changes from
$w_X>-1$ to $w_X<-1$.


title:
The type IIn supernova 1994W: evidence for the explosive ejection of a
  circumstellar envelope

abstract:
  We present and analyse spectra of the Type IIn supernova 1994W obtained
between 18 and 203 days after explosion. During the luminous phase (first 100
d) the line profiles are composed of three major components: (i) narrow P-Cygni
lines with the absorption minima at -700 km/s; (ii) broad emission lines with
BVZI ~4000 km/s; and (iii) broad, smooth wings, most apparent in H-alpha. These
components are identified with an expanding circumstellar (CS) envelope,
shocked cool gas in the forward post-shock region, and multiple Thomson
scattering in the CS envelope, respectively. The absence of broad P-Cygni lines
from the supernova is the result of the formation of an optically thick, cool,
dense shell at the interface of the ejecta and the CS envelope. We model the
supernova deceleration and Thomson scattering wings to recover the density,
radial extent and Thomson optical depth of the CS envelope during the first
month. We reproduce the light curve with a hydrodynamical model and find it to
be powered by a combination of internal energy leakage after the explosion of
an extended pre-supernova (~10^15 cm) and luminosity from circumstellar
interaction. We recover the pre-explosion kinematics of the CS envelope: it is
close to homologous expansion with outer velocity ~1100 km/s and a kinematic
age of ~1.5 yr. The CS envelope's high mass and kinetic energy, combined with
its small age, strongly suggest that the CS envelope was explosively ejected
about 1.5 yr before the supernova explosion.


title: Detection of cosmic filaments using the Candy model

abstract:
  We propose to apply a marked point process to automatically delineate
filaments of the large-scale structure in redshift catalogues. We illustrate
the feasibility of the idea on an example of simulated catalogues, describe the
procedure, and characterize the results. We find the distribution of the length
of the filaments, and suggest how to use this approach to obtain other
statistical characteristics of filamentary networks.


title: Dark matter density profiles from the Jeans equation

abstract:
  We make a simple analytical study of radial profiles of dark matter
structures, with special attention to the question of the central radial
density profile. We let our theoretical assumptions be guided by results from
numerical simulations, and show that at any radius where both the radial
density profile, rho, and the phase-space-like density profile,
rho/sigma^epsilon, are exact power laws, the only allowed density slopes in
agreement with the spherical symmetric and isotropic Jeans equation are in the
range 1< beta <3, where beta = - dln(rho)/dln(r). We also allow for a radial
variation of these power laws, as well as anisotropy, and show how this allows
for more shallow central slopes.


title: Where Did The Moon Come From?

abstract:
  The current standard theory of the origin of the Moon is that the Earth was
hit by a giant impactor the size of Mars causing ejection of iron poor impactor
mantle debris that coalesced to form the Moon. But where did this Mars-sized
impactor come from? Isotopic evidence suggests that it came from 1AU radius in
the solar nebula and computer simulations are consistent with it approaching
Earth on a zero-energy parabolic trajectory. But how could such a large object
form in the disk of planetesimals at 1AU without colliding with the Earth
early-on before having a chance to grow large or before its or the Earth's iron
core had formed? We propose that the giant impactor could have formed in a
stable orbit among debris at the Earth's Lagrange point $L_4$ (or $L_5$). We
show such a configuration is stable, even for a Mars-sized impactor. It could
grow gradually by accretion at $L_4$ (or $L_5$), but eventually gravitational
interactions with other growing planetesimals could kick it out into a chaotic
creeping orbit which we show would likely cause it to hit the Earth on a
zero-energy parabolic trajectory. This paper argues that this scenario is
possible and should be further studied.


title: Nucleosynthesis and the variation of fundamental couplings

abstract:
  We determine the influence of a variation of the fundamental ``constants'' on
the predicted helium abundance in Big Bang Nucleosynthesis. The analytic
estimate is performed in two parts: the first step determines the dependence of
the helium abundance on the nuclear physics parameters, while the second step
relates those parameters to the fundamental couplings of particle physics. This
procedure can incorporate in a flexible way the time variation of several
couplings within a grand unified theory while keeping the nuclear physics
computation separate from any model-dependent assumptions.


title:
An improved approach to measuring H_0 using X-ray and SZ observations of
  galaxy clusters

abstract:
  We present an improved method for predicting the Sunyaev-Zeldovich (SZ)
effect in galaxy clusters from spatially-resolved, spectroscopic X-ray data.
Using the deprojected electron density and temperature profiles measured within
a fraction of the virial radius, and assuming a Navarro, Frenk & White (1995)
mass model, we show how the pressure profile of the X-ray gas can be
extrapolated to large radii, allowing the Comptonization parameter profile for
the cluster to be predicted precisely. We apply our method to Chandra
observations of three X-ray luminous, dynamically relaxed clusters with
published SZ data: RX J1347.5-1145, Abell 1835 and Abell 478. Combining the
predicted and observed SZ signals, we determine improved estimates for the
Hubble constant from each cluster and obtain a weighted mean of
H_0=69\pm8km/s/Mpc for a cosmology with Omega_m=0.3 and Omega_Lambda=0.7. This
result is in good agreement with independent findings from the Hubble Key
Project and the combination of cosmic microwave background and galaxy cluster
data.


title: SPI data analysis: the CESR/Toulouse approach

abstract:
  In order to allow for an efficient and flexible scientific analysis of data
from the SPI imaging spectrometer aboard INTEGRAL, I developed a set of
analysis executables that are publicly available through the internet. The
software is fully compatible with the ISDC data format. It complements software
that is actually available through ISDC, and will be included in the next ISDC
software release. This paper describes the design of my software system and
provides a brief introduction to the executables.


title: The INTEGRAL LMXRB Monitoring Programme

abstract:
  Our collaboration is responsible for the study of a sample of 72 low mass
X-ray binaries (LMXRB) using the INTEGRAL Core Programme data. In this paper we
describe the monitoring programme we have started and the current variability
and spectral results on a sample of 8 persistently bright LMXRBs hosting a
neutron star (Z and Atoll sources). Current results show that among our sample
of sources there seems to be no important difference in the variability of Z
sources with respect to Atolls and the first colour-colour and hardness
intensity diagrams built in the "traditional" energy bands display the expected
patterns. Z sources seem to be harder than the bright Atolls of our sample
(above 20 keV) and present no evident cut-off until about 50 keV. A hint of a
non-thermal hard tail is seen in Sco X-1 with ISGRI and SPI, similarly to what
was previously detected by D'Amico et al. (2001) with RXTE. These results, even
if preliminary, show the importance of such a programme and the potential
underlying it to understand these sources as a class.


title:
Properties of RR Lyrae stars in the Inner Regions of the Large
  Magellanic Cloud

abstract:
  We present the radial velocities, metallicities and the K-band magnitudes of
74 RR Lyrae stars in the inner regions of the LMC. The intermediate resolution
spectra and infrared images were obtained with FORS1 at the ESO VLT and with
the SOFI infrared imager at the ESO NTT.
  The best 43 RR Lyrae with measured velocities yield an observed velocity
dispersion of 61+-7 km/s. We obtain a true LMC RR Lyrae velocity dispersion of
53 km/s, which is higher than the velocity dispersion of any other LMC
population previously measured. This is the first empirical evidence for a
kinematically hot, metal-poor halo in the LMC as discussed in Minniti et al.
(2003).
  Using Layden's (1994) modification of the Delta S method we measured the
metallicity for 23 of our stars. The mean value is [Fe/H] =-1.46+-0.09 dex. The
absolute magnitudes M_V and M_K of RR Lyrae stars are linear functions of
metallicity. In the V band, our data agree with the Olech et al. (2003)
relation, in the K band the slope is flatter.
  The average apparent V luminosity of 70 RR Lyrae stars is <V> = 19.45+-0.04
and the average K luminosity of 37 RR Lyrae stars is <K>=18.20+-0.06. There is
no obvious relation between apparent V magnitude and LogP, while the RR Lyrae K
band magnitudes show a well defined linear trend with LogP.
  Using the Bono et al. (2001) and Bono et al. (2003) theoretical Near-Infrared
Period-Luminosity-Metallicity relations we calculate the LMC distance modulus
18.48+-0.08.


title: OH (1720 MHz) Maser Search Toward the Large Magellanic Cloud

abstract:
  We have carried out a sensitive search for OH (1720 MHz) masers in the Large
Magellanic Cloud (LMC) toward five regions using the Australia Telescope
Compact Array (ATCA). Our source list includes the 30 Doradus region, and four
supernova remnants (SNRs): N44, N49, N120, and N132D. These data have a typical
resolution of ~8 arcsec and rms noise levels of 5-10 mJy/beam. We have detected
OH (1720 MHz) masers in the NE part of 30 Doradus and toward the SNR N49. The
OH (1720 MHz) maser emission in 30 Doradus is coincident with a cluster of
young stars known as ``Knot 1'', and is almost certainly of the star formation
variety. Our spectral resolution (0.68 km/s) is insufficient to detect the
Zeeman effect from the strongest (320 mJy/beam) of the 30 Doradus OH (1720 MHz)
masers, leading to an upper limit to the field strength of 6 mG. The weak OH
(1720 MHz) maser emission (35 mJy/beam) detected toward the LMC SNR N49 is
located just west of a previously identified CO cloud, and are indicative of an
interaction between the SNR and the molecular cloud. Although the statistics
are low, the detection rate seems consistent with that seen for Galactic star
forming regions and SNR type OH (1720 MHz) masers -- both of which are low.


title: Searches for Young Pulsars

abstract:
  I review the results of radio and X-ray searches for pulsations from young
neutron stars, emphasizing work accomplished in the last five years. I cover
undirected searches, as well as directed searches of pulsar wind nebulae, EGRET
gamma-ray sources, and also the search for pulsations from "isolated neutron
stars" (INSs) and "central compact objects".


title:
New Constraints on the Structure and Evolution of the Pulsar Wind Nebula
  3C 58

abstract:
  We present an investigation of the spectral and spatial structure of the
X-ray emission from 3C 58 based on a 350 ks observation with the Chandra X-ray
Observatory. This deep image, obtained as part of the Chandra Large Project
program, reveals new information on nearly all spatial scales in the pulsar
wind nebula (PWN). On the smallest scales we derive an improved limit of T <
1.02 X 10^6 K for blackbody emission from the entire surface of the central
neutron star (NS), confirming the need for rapid, nonstandard cooling in the
stellar interior. Furthermore, we show that the data are consistent with
emission from a light element atmosphere with a similar temperature.
Surrounding the NS, a toroidal structure with a jet is resolved, consistent
with earlier measurements and indicative of an east-west orientation for the
projected rotation axis of the pulsar. A complex of loop-like X-ray filaments
fills the nebula interior, and corresponds well with structures seen in the
radio band. Several of the structures coincide with optical filaments as well.
The emission from the interior of the PWN, including the pulsar, jet, and
filaments, is primarily nonthermal in nature. The power law index steepens with
radius, but appears to also show small azimuthal variations. The outermost
regions of the nebula require a thermal emission component, confirming the
presence of an ejecta-rich swept up shell.


title: Shapley-Ames Galaxies in the Blue and Infrared

abstract:
  The Shapley-Ames Catalog of 1276 galaxies with B < 12.5 is compared with the
Sanders et al. all sky sample of the 629 galaxies with 60 m flux density > 5.24
Jy. The fraction of Shapley-Ames galaxies that are visible in the IR is found
to increase from 0.006 for E or E/S0 galaxies to 0.384 for Sc galaxies. The
subset of Shapley-Ames galaxies that are detected in the IR has a median blue
luminosity that is ~0.8 mag fainter than that of all Shapley-Ames galaxies.
Most of this difference is due to the fact that late-type galaxies (which
contain dust and hot stars) are systematically less luminous in blue light than
are early-type galaxies. Within individual stages along the Hubble sequence no
significant differences are found between the luminosity distributions in blue
light of galaxies that were detected in the infrared and those that were not.
However, our data show a puzzling exception (significant at 99.9%) for SBc
galaxies. For reasons that are not understood Shapley-Ames SBc galaxies, that
are visible in the IR, are more luminous in blue light than those SBc galaxies
that are not detected in the infrared. An other peculiarity of the data is that
Shapley-Ames Sc galaxies galaxies are (at 99.6% confidence) more luminous than
objects of type SBc .


title: Binary Evolution and Neutron Stars in Globular Clusters

abstract:
  We investigate the dynamical formation and evolution of binaries containing
neutron stars in dense globular clusters. Our numerical simulations combine a
simple Monte Carlo prescription for stellar dynamics, a sophisticated binary
population synthesis code, and a small-N-body integrator for computing 3-body
and 4-body interactions. Our results suggest that there is no ``retention
problem,'' i.e., that, under standard assumptions, globular clusters can retain
enough neutron stars to produce the observed numbers of millisecond pulsars. We
also identify the dominant evolutionary and dynamical channels through which
globular clusters produce their two main types of binary millisecond pulsars


title:
Electromagnetic polarization in partially ionized plasmas with strong
  magnetic fields and neutron star atmosphere models

abstract:
  Polarizability tensor of a strongly magnetized plasma and the polarization
vectors and opacities of normal electromagnetic waves are studied for the
conditions typical of neutron star atmospheres, taking account of partial
ionization effects. Vacuum polarization is also included using a new set of
fitting formulae that are accurate for wide range of field strengths. The full
account of the coupling of the quantum mechanical structure of the atoms to
their center-of-mass motion across the magnetic field is shown to be crucial
for the correct evaluation of the polarization properties and opacities of the
plasma. The self-consistent treatment of the polarizability and absorption
coefficients proves to be necessary if the ionization degree of the plasma is
low, which can occur in the atmospheres of cool or ultramagnetized neutron
stars. Atmosphere models and spectra are presented to illustrate the importance
of such self-consistent treatment.


title: Galaxy evolution in clusters from z=1 to z=0

abstract:
  The XMM--LSS project is detecting distant clusters of low mass, quite
comparable in mass to the ones in the local universe. This allows a direct
comparison of galaxy properties at different redshifts in ``similar'' clusters.
We present here first results on the evolution of the reddest galaxies in ~25
clusters/groups at ~0.3< z <~1.0 and for the whole galaxy population in the
same clusters. The emerging picture from the current study is that the
counterparts of present day clusters tend to show two or more distinct
populations : a relatively old (z_f>2-5) population evolving passively together
with a younger population, ostensibly responsible for the apparent brightening
of the characteristic magnitudes, m*.


title: Imaging chemical differentiation around the low-mass protostar L483-mm

abstract:
  This paper presents a millimeter wavelength aperture-synthesis study of the
spatial variations of the chemistry in the envelope around the deeply embedded
low-mass protostar L483-mm on 1000 AU (5") scales. Lines of 8 molecular species
including CN, C18O, CS, C34S, HCN, H13CN, HCO+ and N2H+ have been observed
using the Owens Valley Radio Observatory Millimeter Array. Continuum emission
at 2.7-3.4 millimeter is well-fit by a pure envelope model down to the
sensitivity of the interferometer without introducing a disk/compact source, in
contrast to what is seen for other protostars. A velocity gradient in the
densest material is traced by HCN, CS and N2H+, and is perpendicular to the
large-scale CO outflow, with a pattern consistent with rotation around a 1
solar mass central object. Velocity gradients in the propagation direction of
the outflow suggest a clear interaction between the outflowing material and
"quiescent" core. The C18O observations are fit with a "drop" abundance profile
where CO is frozen-out in a region of the envelope with temperatures lower than
40 K and densities higher than 1.5e5 cm^{-3}, which is also required to
reproduce single-dish observations. The N2H+ emission strongly resembles that
of NH3 and is found to be absent toward the central continuum source. This is a
direct consequence of the high CO abundances in the inner region as illustrated
by a chemical model for the L483 envelope. The observed CN emission forms a
spatial borderline between the outflowing and quiescent material probed by,
respectively, HCO+ and N2H+, and also shows intermediate velocities compared to
these two species. A scenario is suggested in which CN is enhanced in the walls
of an outflow cavity due to the impact of UV irradiation either from the
central protostellar system or related to shocks caused by the outflow.


title: The GRB/XRF-SN Association

abstract:
  There is mounting evidence that long duration gamma ray bursts (GRBs) and
X-ray flashes (XRFs) are produced by highly relativistic and narrowly
collimated jets ejected in core collapse supernova (SN) explosions akin to SN
1998bw. We review the history of the GRB-SN association idea and its
observational verification. We summarize the present evidence for a GRB/XRF-SN
association. We comment on the possibility that most, perhaps all, SN
explosions produce GRBs, including SNe of Type Ia which may produce short
GRBs/XRFs. We list the major open questions that follow from a GRB/XRF-SN
association. Possible uses of the GRB-SN association in cosmology are pointed
out.


title:
High resolution imaging polarimetry of HL Tau and magnetic field
  structure

abstract:
  We present high quality near infrared imaging polarimetry of HL Tau at 0.4 to
0.6 arcsec resolution, obtained with Subaru/CIAO and UKIRT/IRCAM. 3-D Monte
Carlo modelling with aligned oblate grains is used to probe the structure of
the circumstellar envelope and the magnetic field, as well as the dust
properties. At J band the source shows a centrosymmetric pattern dominated by
scattered light. In the H and K bands the central source becomes visible and
its polarisation appears to be dominated by dichroic extinction, with a
position angle inclined by ~40 degrees to the disc axis. The polarisation
pattern of the environs on scales up to 200 AU is consistent with the same
dichroic extinction signature superimposed on the centrosymmetric scattering
pattern. These data can be modelled with a magnetic field which is twisted on
scales from tens to hundreds of AU, or alternatively by a field which is
globally misaligned with the disc axis. A unique solution to the field
structure will require spatially resolved circular polarisation data. The best
fit Monte Carlo model indicates a shallow near infrared extinction law. When
combined with the observed high polarisation and non-negligible albedo these
constraints can be fitted with a grain model involving dirty water ice mantles
in which the largest particles have radii slightly in excess of 1 um. The best
fit model has an envelope structure which is slightly flattened on scales up to
several hundred AU. Both lobes of the bipolar outflow cavity contain a
substantial optical depth of dust (not just within the cavity walls). Curved,
approximately parabolic, cavity walls fit the data better than a conical
cavity. The small inner accretion disc observed at millimetre wavelengths is
not seen at this spatial resolution.


title:
First simultanous X-ray and optical observations of rapid variability of
  supercritical accretor SS433

abstract:
  We present results of first simultaneous optical and X-ray observations of
peculiar binary system SS433. For the first time, chaotic variability of SS433
in the optical spectral band (R band) on time scales as small as tens of
seconds was detected. We find that the X-ray flux of SS433 is delayed with
respect to the optical emission by approximately 80 sec. Such a delay can be
interpreted as the travel time of mass accretion rate perturbations from the
jet base to the observed X-ray emitting region. In this model, the length of
the supercritical accretion disk funnel in SS433 is ~1e12 cm.


title: A new multidimensional AMR Hydro+Gravity Cosmological code

abstract:
  A new cosmological multidimensional hydrodynamic and N-body code based on an
Adaptive Mesh Refinement scheme is described and tested. The hydro part is
based on modern high-resolution shock-capturing techniques, whereas N-body
approach is based on the Particle Mesh method. The code has been specifically
designed for cosmological applications. Tests including shocks, strong
gradients, and gravity have been considered. A cosmological test based on Santa
Barbara cluster is also presented. The usefulness of the code is discussed. In
particular, this powerful tool is expected to be appropriate to describe the
evolution of the hot gas component located inside asymmetric cosmological
structures.


title: Deep near-infrared spectroscopy of submillimetre-selected galaxies

abstract:
  We present the results of deep near-infrared spectroscopy of seven
submillimetre-selected galaxies from the SCUBA 8-mJy and CUDSS surveys. These
galaxies were selected because they are too faint to be accessible to optical
spectrographs on large telescopes. We obtain a spectroscopic redshift for one
object, and likely redshifts for two more, based on a combination of marginal
emission line detections and the shape of the continuum. All three redshifts
broadly agree with estimates from their radio/submm spectral energy
distributions. From the emission line strengths of these objects, we infer star
formation rates of 10-25 Msun/yr, while the lack of detections in the other
objects imply even lower rates. By comparing our results with those of other
authors, we conclude it is likely that the vast majority (more than 90 per
cent) of the star formation in these objects is completely extinguished at
rest-frame optical wavelengths, and the emission lines originate in a
relatively unobscured region. Finally, we look at future prospects for making
spectroscopic redshift determinations of submm galaxies.


title:
Selection of quasar candidates from combined radio and optical surveys
  using neural networks

abstract:
  The application of supervised artificial neural networks (ANNs) for quasar
selection from combined radio and optical surveys with photometric and
morphological data is investigated, using the list of candidates and their
classification from White et al. (2000). Seven input parameters and one output,
evaluated to 1 for quasars and 0 for nonquasars, were used, with architectures
7:1 and 7:2:1. Both models were trained on samples of ~800 sources and yielded
similar performance on independent test samples, with reliability as large as
87% at 80% completeness. For comparison the quasar fraction from the original
candidate list was 56%. The accuracy is similar to that found by White et al.
using supervised learning with oblique decision trees. This performance
probably approaches the maximum value achievable with this database.
Probabilities for the 98 candidates without spectroscopic classification in
White et al. are presented and compared with the results from their work,
showing a good agreement. This is the first analysis of the performance of ANNs
for the selection of quasars. Our work shows that ANNs provide a promising
technique for the selection of specific object types in astronomical databases.


title:
The very early afterglow powered by the ultra-relativistic mildly
  magnetized outflows

abstract:
  In the Poynting Flux dominated outflow (the initial ratio of the
electromagnetic energy flux to the particle energy flux $\sigma_0\gg1$) model
for Gamma-ray bursts, nearly half of the internally dissipated magnetic energy
is converted into the prompt $\gamma-$ray energy emission and the rest is
converted into the kinetic energy of the outflow. Consequently, at the end of
the $\gamma-$ray burst, $\sigma$ decreases significantly ($\sigma\sim 1$ or
even smaller). We numerically investigate the very early reverse shock emission
powered by such mildly magnetized outflows interacting with medium--uniform
interstellar medium (ISM) or stellar wind (WIND). We show that for
$\sigma\sim0.05-1$ and typical parameters of Gamma-ray bursts, both the
ISM-ejecta interaction and the WIND-ejecta interaction can power very strong
optical emission ($m_{\rm R}\sim 10-12{\rm th}$ magnitude or even brighter).
Similar to the very early afterglow powered by the non-magnetized ejecta
interacting with the external medium, the main difference between the
ISM-ejecta interaction case and the WIND-ejecta interaction case is that,
before the reverse shock crosses the ejecta, the R-band emission flux increases
rapidly for the former, but for the latter it increases only slightly. (The
abstract has been shortened). We suggest that the linear polarization detection
of the early multi-wavelength afterglow is highly needed to see whether the
outflows powering GRBs are magnetized or not.


title: On the cosmological evolution of quasar black-hole masses

abstract:
  Virial black-hole mass estimates are presented for 12698 quasars in the
redshift interval 0.1<z<2.1, based on modelling of spectra from the Sloan
Digital Sky Survey (SDSS) first data release . The black-hole masses of the
SDSS quasars are found to lie between $\simeq10^{7}\Msun$ and an upper limit of
$\simeq 3\times 10^{9}\Msun$, entirely consistent with the largest black-hole
masses found to date in the local Universe. The estimated Eddington ratios of
the broad-line quasars (FWHM \geq2000 km s^{-1}) show a clear upper boundary at
L_{bol}/L_{Edd}~1, suggesting that the Eddington luminosity is still a relevant
physical limit to the accretion rate of luminous broad-line quasars at $z\leq
2$. By combining the black-hole mass distribution of the SDSS quasars with the
2dF quasar luminosity function, the number density of active black holes at
$z\simeq 2$ is estimated as a function of mass. By comparing the estimated
number density of active black holes at $z\simeq 2$ with the local mass density
of dormant black holes, we set lower limits on the quasar lifetimes and find
that the majority of black holes with mass $\geq 10^{8.5}\Msun$ are in place by
$\simeq 2$.


title:
Helical Magnetic Fields Associated with the Relativistic Jets of Four BL
  Lac Objects

abstract:
  Evidence has been mounting that many of the transverse jet B fields observed
in BL Lac objects on parsec scales represent the dominant vvroidal compoent of
the intrinsic jet B fields. Such fields could come about, for example, as a
result of the "winding up" of an initial "seed" field with a significant
longitudinal component by the rotation of the central accreting object. If this
is the case, this should give rise to gradients in the rotation measure (RM)
across the jets, due to the systematic change in the line-of-sight component of
the jet B field. We present evidence for transverse RM gradients in four BL Lac
objects, strengthening arguments that the jets of these objects do indeed have
toroidal or helical B fields. This underlines the view of the jets as
fundamentally electromagnetic structures, and suggests that they may well carry
non-zero currents. It also provides a natural means to collimate the jets.


title: Bright metal-poor variables: why "Anomalous" Cepheids?

abstract:
  We investigate the theoretical scenario concerning the large sample of
variables recently discovered in the dwarf, metal-poor irregular galaxy Leo A,
focusing the attention on the "Anomalous" Cepheid phenomenon and its
correlation with RR Lyrae stars, Classical and Population II Cepheids. To this
purpose, we make use of suitable stellar and pulsation models to depict the
pulsational history of evolutionary structures with metallicity Z=0.0004,
finding that He-burning pulsators are expected only outside the mass interval ~
0.8-1.7 Mo. The dependence on metal content of this scenario has been
investigated over the range Z=0.0002 to 0.008. One finds that the edges of the
pulsational strip for the more massive class of pulsators appear independent of
metallicity, but with the minimum mass of these bright pulsators which
decreases when decreasing the metallicity, thus decreasing the predicted
minimum luminosity and period. Comparison with data for Cepheids in Leo A and
in the moderately metal rich extragalactic stellar system Sextans A discloses
an encouraging agreement with the predicted pulsational scenario. On this
basis, we predict that in a stellar system where both RR Lyrae stars and
Cepheids are observed, their magnitude difference may help in constraining both
the metal content and the distance. The current classification of metal-poor
Cepheids is shortly discussed, advancing the suggestion for an updated
terminology abreast of the current knowledge of stellar evolution.


title: B polarization of the CMB from Faraday rotation

abstract:
  We study the effect of Faraday rotation due to a homogeneous magnetic field
on the polarization of the cosmic microwave background (CMB). Scalar
fluctuations give rise only to parity-even E-type polarization of the CMB.
However in the presence of a magnetic field, a non-vanishing parity-odd B-type
polarization component is produced through Faraday rotation. We derive the
exact solution for the E and B modes generated by scalar perturbations
including the Faraday rotation effect of a uniform magnetic field, and evaluate
their cross-correlations with temperature anisotropies. We compute the angular
autocorrelation function of the B-modes in the limit that the Faraday rotation
is small. We find that primordial magnetic fields of present strength around
$B_0=10^{-9}$G rotate E-modes into B-modes with amplitude comparable to those
due to the weak gravitational lensing effect at frequencies around $\nu=30$
GHz. The strength of B-modes produced by Faraday rotation scales as
$B_0/\nu^2$. We evaluate also the depolarizing effect of Faraday rotation upon
the cross correlation between temperature anisotropy and E-type polarization.


title:
Must Cosmological Perturbations Remain Non-Adiabatic After Multi-Field
  Inflation?

abstract:
  Even if non-adiabatic perturbations are generated in multi-field inflation,
the perturbations will become adiabatic if the universe after inflation enters
an era of local thermal equilibrium, with no non-zero conserved quantities, and
will remain adiabatic as long as the wavelength is outside the horizon, even
when local thermal equilibrium no longer applies. Small initial non-adiabatic
perturbations associated with imperfect local thermal equilibrium remain small
when baryons are created from out-of-equilibrium decay of massive particles, or
when dark matter particles go out of local thermal equilibrium.


title:
An X-ray Timing Study of XTE J1550--564: Evolution of the Low Frequency
  QPO for the Complete 2000 Outburst

abstract:
  We report on RXTE observations of the microquasar XTE J1550 during a ~70 day
outburst in April-June 2000. We focus here on the temporal properties of the
source and study the behavior of low frequency (0.1-10 Hz) quasi periodic
oscillations (LFQPO), which seem to be of different types. We focus on the
so-called type C (according to the classification of Remillard and
collaborators), which corresponds to a strong 0.1-6 Hz LFQPO, found to be
present during at least 17 observations. We find that the frequency of the QPO
is better correlated with the soft X-ray (< 7 keV) flux than with the hard flux
(> 7 keV). If soft X-rays represent the behavior of an accretion disk, the
relation shows that the disk may set the LFQPO frequency. In two cases, the
identification of the type of QPO is not straightforward. If the QPOs in those
two cases are type A (or B), then we may be seeing the QPO type alternate
between type C and type A (or B), and this may represent some rapid changes in
the physical properties of the accretion flow, before the system stabilizes and
slowly decays toward the end of the outburst. On the other hand, if all the
QPOs are of type C, we may be observing an inversion in the frequency vs. flux
relation, similar to that seen in GRO J1655-40. We discuss the QPO behavior in
the framework of theoretical models.


title: A Far Infrared Polarimeter

abstract:
  We describe an experiment to measure calibration sources, the polarization of
Cosmic Microwave Background Radiation (CMBR) and the polarization induced on
the CMBR from S-Z effects, using a polarimeter, MITOPol, that will be employed
at the MITO telescope. Two modulation methods are presented and compared: an
amplitude modulation with a Fresnel double rhomb and a phase modulation with a
modified Martin-Puplett interferometer. A first light is presented from the
campaign (summer 2003) that has permitted to estimate the instrument spurious
polarization using the second modulation method.


title:
Disk-to-halo mass ratio evaluations based on the numerical models of
  collisionless disks

abstract:
  We propose that the lower bound of the stellar radial velocity dispersion c_r
of an equilibrium stellar disk is determined by the gravitational stability
condition. We compared the estimates of stellar velocity dispersion at radii
r>(1.5 - 2)R_0 (where R_0 is the photometric radial scalelength of a disk),
found in the literature, with the minimal values of c_r necessary for the disk
to be in a stable state, using the results of numerical simulations of 3D
collisional disks. This approach enables to estimate an upper limit of the
local surface density and (if R_0 is known) a total masses of a disk and a dark
halo. We argue that the old stellar disks of spiral galaxies with active star
formation usually have the velocity dispersions which are close to the expected
marginal values. A rough values of disk-to-total mass ratios (within the fixed
radius) are found for about twenty spiral galaxies. Unlike spirals, the disks
of the ``red'' Sa--S0 galaxies are evidently ``overheated'': their radial
dispersion of velocities at r ~ 2 R_0 exceeds significantly the marginal values
for gravitational stability.


title:
A Hubble Space Telescope WFPC2 Investigation of the Disk-Halo Interface
  in NGC891

abstract:
  We present deep narrowband observations with high spatial resolution of
extraplanar diffuse ionized gas in the halo of NGC891, obtained with the WFPC2
on-board the HST. Our H-alpha observations, centered on the northern part of
NGC891, reveal an extended gaseous halo, which fills almost the entire field of
view of our WFPC2 observation. The majority of the H-alpha emission is diffuse.
Several discrete features (e.g., filaments) are visible as well. Some of the
filaments reach distances of up to 2.2 kpc above the galactic plane, and are
extremely collimated, even at high galactic latitudes. We compare the
morphology of these filaments with theoretical models, which describe possible
transport mechanisms in a general way. We also investigate extraplanar dust
features, which are best visible in unsharp-masked images of our broadband
F675W image, and we compare them to the spatial distribution of DIG filaments.
Individual dust features, however, are not spatially correlated with diffuse
ionized gas counterparts, such as individual filaments. Quite interestingly,
the orientation of the dust features changes from being mostly aligned
perpendicular to the disk at low galactic latitudes, to a parallel alignment at
high |z|. We compare the diffuse ionized gas distribution to the hot ionized
medium, traced by X-ray observations performed by Chandra. There exists a good
correlation of the presence of the warm and hot ionized gas, in particular, an
X-ray bright region at |z| ~ 1-1.5 kpc fills the entire northern halo region,
whereas the intensity in the midplane is considerably depressed. We also
compare the sizes of individual H-alpha emission line features in the midplane
of NGC891 with similar structures that are known in our Milky Way and in the
LMC.


title: Variable stars towards the bulge of M31: the AGAPE catalogue

abstract:
  We present the AGAPE astrometric and photometric catalogue of 1579 variable
stars in a 14'x10' field centred on M31. This work is the first survey devoted
to variable stars in the bulge of M31. The R magnitudes of the objects and the
B-R colours suggest that our sample is dominated by red long-period variable
stars (LPV), with a possible overlap with Cepheid-like type II stars. Twelve
nova candidates are identified. Correlations with other catalogues suggest that
2 novae could be recurrent novae and provide possible optical counterparts for
2 supersoft X-ray sources candidates observed with Chandra.


title:
Photometry and the Metallicity Distribution of the Outer Halo of M31.
  II. The 30 Kpc Field

abstract:
  We present the results of a wide-field (V,I) photometric study of the
red-giant branch (RGB) stars in the outer halo of M31, in a field located 30 to
35 kpc from the center of the galaxy along the southeast minor axis. At this
remote location, we find that RGB stars belonging to M31 are sparsely but
definitely present, after statistical subtraction of field contamination. We
derive the metallicity distribution (MDF) for the halo stars using
interpolation within a standard (I,V-I) grid of RGB evolutionary tracks. The
halo MDF is quite broad but dominated by a moderately high-metallicity
population peaking at [m/H] ~ -0.5, strikingly different from the [m/H] ~ -1.3
level which characterizes the outer halo of the Milky Way. However,the shape
and peak metallicity for this region are entirely similar to those found in
other studies for the inner regions of the M31 halo, particularly our previous
study of a 20-kpc region (Durrell, Harris, & Pritchet 2001) employing similar
data. In summary, we find no evidence for a metallicity gradient or systematic
change in the MDF out to quite large distances in the M31 halo: it appears to
be a homogeneous and moderately metal-rich subsystem of the galaxy at all
locations. The star counts in the 30-kpc field are also consistent with the
r^1/4 law that fits the interior regions of the M31 spheroid surface brightness
profile. The metal-rich MDF and the r^1/4 spheroid suggests M31 more strongly
resembles a giant elliptical galaxy than other, Milky-Way-like, spirals.


title: Conference Summary: AGN Physics with the Sloan Digital Sky Survey

abstract:
  The ``AGN Physics with the Sloan Digital Sky Survey'' conference was held at
Princeton University in July 2003 to bring together groups working inside and
outside of the SDSS collaboration at radio through X-ray wavelengths to discuss
the common goal of better understanding the physics of Active Galactic Nuclei
(AGN). Although we still do not have a full understanding of AGN, much progress
has been made in recent years. In this conference summary, we concentrate on
those topics discussed at the meeting where we believe that there has been
significant change or where there is a new standard of comparison, as well as
on important new trends in AGN research.


title: Neutral Hydrogen in Arp 158

abstract:
  We present 21 cm observations of Arp 158. We have performed a study of the
neutral hydrogen (HI) to help us understand the overall formation and evolution
of this system. This is a disturbed system with distinct optical knots
connected by a linear structure embedded in luminous material. There is also a
diffuse spray to the southeast. The HI seems to be made up of three distinct,
kinematically separate systems. Arp 158 bears a certain optical resemblance to
NGC 520 (Arp 157), which has been identified as a mid-stage merger. From our 21
cm observations of Arp 158, we also see a comparable HI content with NGC 520.
These similarities suggest that Arp 158 is also an intermediate stage merger.


title: CMB power spectrum estimation using noncircular beams

abstract:
  The measurements of the angular power spectrum of the Cosmic Microwave
Background (CMB) anisotropy has proved crucial to the emergence of cosmology as
a precision science in recent years. In this remarkable data rich period, the
limitations to precision now arise from the the inability to account for finer
systematic effects in data analysis. The non-circularity of the experimental
beam has become progressively important as CMB experiments strive to attain
higher angular resolution and sensitivity. We present an analytic framework for
studying the leading order effects of a non-circular beam on the CMB power
spectrum estimation. We consider a non-circular beam of fixed shape but
variable orientation. We compute the bias in the pseudo-$C_l$ power spectrum
estimator and then construct an unbiased estimator using the bias matrix. The
covariance matrix of the unbiased estimator is computed for smooth,
non-circular beams. Quantitative results are shown for CMB maps made by a
\emph{hypothetical} experiment with a non-circular beam comparable to our fits
to the WMAP beam maps described in the appendix and uses a \emph{toy} scan
strategy. We find that significant effects on CMB power spectrum can arise due
to non-circular beam on multipoles comparable to, and beyond, the inverse
average beam-width where the pseudo-$C_l$ approach may be the method of choice
due to computational limitations of analyzing the large datasets from current
and near future CMB experiments.


title: The continued spectral evolution of the neutron star RX J0720.4-3125

abstract:
  We observed the isolated neutron star RX J720.4-3125 with Chandra's Low
Energy Transmission Grating Spectrometer, following the XMM-Newton discovery of
long term spectral evolution of this source. The new observation shows that the
spectrum of RX J720.4-3125 has continued to change in the course of 5 months.
It has remained hard, similar to the last XMM-Newton observation, but the
strong depression observed with XMM-Newton at long wavelengths has disappeared.
Contrary to the XMM-Newton observations, the new Chandra observation shows that
the flux increase at short wavelengths and the decrease at long wavelengths do
not necessarily occur simultaneously.


title: The Progenitors of Core-Collapse Supernovae

abstract:
  We present maps of the nature of single star progenitors of supernovae and
their remnants in mass and metallicity space. We find our results are similar
to others but we have gone further in varying the amount of mixing and using
various mass-loss schemes to see how the maps change. We find that
extra-mixing, in the form of convective overshooting, moves boundaries such as
the minimum mass for a supernova or WR star to lower masses. We also find that
the pre-WR mass-loss determines the shape of our maps. We find that different
mass-loss rates lead to quite different results. We find that the rise in
luminosity at 2nd dredge-up places quite tight constraints on the masses of
some progenitors and in particular the progenitor of supernova 2003gd.


title:
New Calibrations of Pulsational Absolute Magnitudes of Field RR Lyrae
  Stars Using Revised Dependencies of Temperatures, Masses, and Periods on
  Metallicity

abstract:
  The pulsational method to estimate the absolute magnitudes of RR Lyrae stars
is updated with new data on field-star metallicities by Layden, a new
calibration of the (B-V)_0-temperature correlation from recent atmospheric
models by Bell and Tripicco, and new mass estimates by Bono et al. New linear
and non-linear calibrations of M_V(RR)=f([Fe/H]) are derived that depend on the
nature of the adopted envelope in a diagram of log period versus metallicity
fitted to the shortest period field variables in each metallicity range,
together with the stated assumptions on the colour of the stars at that
envelope. These new cali- brations are compared with a recent non-linear
calibration by Caputo et al. The theoretical luminosity zero points for each of
the three new calibrations derived here agree with each other to within 0.1 mag
over the metallicity range of -1.0>[Fe/H]>-2.0. Comparison with the empirical
absolute magnitude calibra- tion of M_V(RR)=+0.52 at [Fe/H]=-1.5 by Clementini
at al. from RR Lyraes in LMC also shows agreement at the 0.05 mag level at the
stated metallicity. Our final compromise pulsational calibration is,
M_V(RR)=0.82 + 0.20([Fe/H]) with the caveat that the true relation is likely to
be non-linear at the 0.1 mag level for [Fe/H] values between -0.5 and -2.0,
hence with variable dM_V/d([Fe/H]) slopes that cover the range from 0 to 0.6
for different metallicities. (...)


title: Validating the FLASH Code: Vortex-Dominated Flows

abstract:
  As a component of the Flash Center's validation program, we compare FLASH
simulation results with experimental results from Los Alamos National
Laboratory. The flow of interest involves the lateral interaction between a
planar Ma=1.2 shock wave with a cylinder of gaseous sulfur hexafluoride (SF_6)
in air, and in particular the development of primary and secondary
instabilities after the passage of the shock. While the overall evolution of
the flow is comparable in the simulations and experiments, small-scale features
are difficult to match. We focus on the sensitivity of numerical results to
simulation parameters.


title:
Short gamma-ray bursts as a possible probe of binary neutron star
  mergers

abstract:
  We study the properties of short gamma-ray bursts (GRBs), based on the
assumption that they are all connected to the binary neutron star mergers,
whose formation mechanism contains a large amount of uncertainty. In
particular, the merger time distribution is focused on, which is essential for
short GRB rate estimate; we simply parameterize it as P_m(t)\propto t^\alpha
with lower cutoff time-scale \tau. The short GRB rate, calculated using such a
parameterization with a specific model of cosmic star formation rate, is found
to be quite insensitive to the value of \tau, but considerably sensitive to
\alpha. With such formation rate models, the peak flux distribution observed by
BATSE is fitted. In the fitting process, the local short GRB rate \rho_0 is
treated as one of free parameters, giving the best fit when \rho_0 = 0.1--2
yr^{-1} Gpc^{-3}, depending on the other free parameters as well as the
formation rate model represented by (\tau,\alpha). We also discuss several
implications for the intrinsic properties of possible sources of short GRBs,
such as jet structure, intrinsic luminosity function, and intrinsic duration
distribution.


title:
Metal abundances of RR Lyrae stars in the bar of the Large Magellanic
  Cloud

abstract:
  Metallicities ([Fe/H]) from low resolution spectroscopy obtained with the
Very Large Telescope (VLT) are presented for 98 RR Lyrae and 3 short period
Cepheids in the bar of the Large Magellanic Cloud. Our metal abundances have
typical errors of +/-0.17 dex. The average metallicity of the RR Lyrae stars is
[Fe/H]=-1.48 +/- 0.03 +/- 0.06 on the scale of Harris (1996). The star-to-star
scatter (0.29 dex) is larger than the observational errors, indicating a real
spread in metal abundances. The derived metallicities cover the range -2.12 <
[Fe/H] <-0.27, but there are only a few stars having [Fe/H] > -1. For the
ab-type variables we compared our spectroscopic abundances with those obtained
from the Fourier decomposition of the light curves. We find good agreement
between the two techniques, once the systematic offset of 0.2 dex between the
metallicity scales used in the two methods is taken into account. The
spectroscopic metallicities were combined with the dereddened apparent
magnitudes of the variables to derive the slope of the luminosity-metallicity
relation for the LMC RR Lyrae stars: the resulting value is 0.214 +/- 0.047
mag/dex. Finally, the 3 short period Cepheids have [Fe/H] values in the range
-2.0 < [Fe/H] <-1.5 . They are more metal-poor than typical LMC RR Lyrae stars,
thus they are more likely to be Anomalous Cepheids rather than the short period
Classical Cepheids that are being found in a number of dwarf Irregular
galaxies.


title:
Primordial Magnetic Fields in the Post-recombination Era and Early
  Reionization

abstract:
  We explore the ways in which primordial magnetic fields influence the thermal
and ionization history of the post-recombination universe. After recombination
the universe becomes mostly neutral resulting also in a sharp drop in the
radiative viscosity. Primordial magnetic fields can then dissipate their energy
into the intergalactic medium (IGM) via ambipolar diffusion and, for small
enough scales, by generating decaying MHD turbulence. These processes can
significantly modify the thermal and ionization history of the
post-recombination universe. We show that the dissipation effects of magnetic
fields which redshifts to a present value $B_{0}=3\times 10^{-9}$ Gauss
smoothed on the magnetic Jeans scale and below, can give rise to Thomson
scattering optical depths $\tau \ga 0.1$, although not in the range of
redshifts needed to explain the recent WMAP polarization observations. We also
study the possibility that primordial fields could induce the formation of
subgalactic structures for $z \ga 15$. We show that early structure formation
induced by nano-Gauss magnetic fields is potentially capable of producing the
early re-ionization implied by the WMAP data. Future CMB observations will be
very useful to probe the modified ionization histories produced by primordial
magnetic field evolution and constrain their strength.


title:
Direct versus indirect detection in mSUGRA with self-consistent halo
  models

abstract:
  We perform a detailed analysis of the detection prospects of neutralino dark
matter in the mSUGRA framework. We focus on models with a thermal relic
density, estimated with high accuracy using the DarkSUSY package, in the range
favored by current precision cosmological measurements. Direct and indirect
detection rates are computed implementing two models for the dark matter halo,
tracing opposite regimes for the phase of baryon infall, with fully consistent
density profiles and velocity distribution functions. This has allowed, for the
first time, a fully consistent comparison between direct and indirect detection
prospects. We discuss all relevant regimes in the mSUGRA parameter space,
underlining relevant effects, and providing the basis for extending the
discussion to alternative frameworks. In general, we find that direct detection
and searches for antideuterons in the cosmic rays seems to be the most
promising ways to search for neutralinos in these scenarios.


title:
RR Lyrae stars in Galactic globular clusters.III. Pulsational
  predictions for metal content Z=0.0001 to Z=0.006

abstract:
  The results of nonlinear, convective models of RR Lyrae pulsators with metal
content Z=0.0001 to 0.006 are discussed and several predicted relations
connecting pulsational (period and amplitude of pulsation) and evolutionary
parameters (mass, absolute magnitude and color of the pulsator) are derived.
These relations, when linked with the average mass of RR Lyrae stars, as
suggested by horizontal branch evolutionary models, provide a ``pulsational''
route to the determination of the distance modulus, both apparent and
intrinsic, of RR Lyrae rich globular clusters. Based on a preliminary set of
synthetic horizontal branch simulations, we compare the predicted relations
with observed variables in selected globular clusters (M2, M3, M5, M15, M55,
M68, NGC 1851, NGC 3201, NGC 5466, NGC 6362, NGC 6934 and IC 4499). We show
that the distance moduli inferred by the various theoretical relations are
mutually consistent within the errors, provided that the value of the
mixing-length parameter slightly increases from the blue to the red edge of the
pulsation region.
  Moreover, we show that the relative ``pulsational'' distance moduli fit well
previous empirical results and that the parallax of the prototype variable RR
Lyr, as inferred by the predicted Period-Wasenheit relation, is in close
agreement with the HST astrometric measurement.


title: Are QSO2 hiding among EROs?

abstract:
  We present the results of a deep (80 ks) XMM-Newton survey of one of the
largest sample of near-infrared selected Extremely Red Objects (R-K>5)
available to date (~300 objects, Daddi et al. 2000). The fraction of
individually detected, X-ray emitting EROs is of the order of ~3.5%, down to
F_x > 4x10^-15 cgs and Ks<19.2. In order to derive the X-ray intrinsic
properties of AGN EROs and to place our findings in a broader context, we have
also considered all the X-ray detected EROs available in the literature. The
X-ray, optical, and near-infrared properties of those X-ray selected EROs with
a spectroscopic or photometric redshift nicely match those expected for quasars
2, the high-luminosity, high-redshift obscured AGNs predicted in XRB synthesis
models.


title: Searches for Cosmic Antimatter

abstract:
  We know from experimental high energy physics that whenever matter is
created, an equal amount of antimatter is also created. However, we live in a
large region of the universe where the antimatter can not constitute more than
a very small fraction of the total mass. The cosmic antimatter problem has been
addressed since the beginning of modern cosmology, but no definite answer has
been formulated despite of the several approaches that can be found in the
literature. In this paper we will make a historical review and we will focus on
the experimental techniques that has been proposed to reveal directly and
indirectly the presence of cosmic antimatter in the universe. Indirect searches
can be carried on with the measurements of the electromagnetic radiation in the
microwave and gamma-ray range, and of the neutrino flavour, whereas direct
searches lay on the measurement of the cosmic rays and probe shorter distances.
Finally, the current limits on the cosmic antimatter to matter ratio are
compared to the sensitivity of future experiments.


title:
A Deep WSRT 1.4 GHz Radio Survey of the Spitzer Space Telescope FLSv
  Region

abstract:
  The First Look Survey (FLS) is the first scientific product to emerge from
the Spitzer Space Telescope. A small region of this field (the verification
strip) has been imaged very deeply, permitting the detection of cosmologically
distant sources. We present Westerbork Synthesis Radio Telescope (WSRT)
observations of this region, encompassing a ~1 sq. deg field, centred on the
verification strip (J2000 RA=17:17:00.00, DEC=59:45:00.000). The radio images
reach a noise level of ~ 8.5 microJy/beam - the deepest WSRT image made to
date. We summarise here the first results from the project, and present the
final mosaic image, together with a list of detected sources. The effect of
source confusion on the position, size and flux density of the faintest sources
in the source catalogue are also addressed. The results of a serendipitous
search for HI emission in the field are also presented. Using a subset of the
data, we clearly detect HI emission associated with four galaxies in the
central region of the FLSv. These are identified with nearby, massive galaxies.


title:
A kinetic control of the heliospheric interface hydrodynamics of
  charge-exchanging fluids

abstract:
  It is well known that the Solar System is presently moving through a
partially ionized local interstellar medium. This gives rise to a counter-flow
situation requiring a consistent description of behaviour of the two fluids --
ions and neutral atoms -- which are dynamically coupled by mutual charge
exchange processes. Solutions to this problem have been offered in the
literature, all relying on the assumption that the proton fluid, even under
evidently nonequilibrium conditions, can be expected to stay in a
highly-relaxated distribution function given by mono-Maxwellians shifted by the
local proton bulk velocity. Here we check the validity of this assumption,
calculating on the basis of a Boltzmann-kinetic approach the actually occurring
deviations. As we show, especially for low degrees of ionization, $\xi \le
0.3$, both the H-atoms and protons involved do generate in the heliospheric
interface clearly pronounced deviations from shifted Maxwellians with
asymmetrically shaped distribution functions giving rise to non-convective
transport processes and heat conduction flows. Also in the inner heliosheath
region and in the heliotail deviations of the proton distribution from the
hydrodynamic one must be expected. This sheds new light on the correctness of
current calculations of H-atom distribution functions prevailing in the inner
heliosphere and also of the Lyman-$\alpha $ absorption features in stellar
spectra due to the presence of the hydrogen wall atoms. Deviations from
LTE-functions would be even more pronounced in magnetic interfaces, which via
CGL-effects cause temperature anisotropies to arise.


title:
Faraday Rotation of the Cosmic Microwave Background Polarization and
  Primordial Magnetic Field Properties

abstract:
  Measurements of the Faraday rotation of the cosmic microwave background
radiation (CMBR) polarization could provide evidence for the existence of
primordial magnetic fields. The Faraday rotation could also allow the study of
some properties of these fields. In this paper, we calculate the angular
dependence of the Faraday rotation correlator for different assumptions about
the spectral index and correlation length of the magnetic field. We show that
the helical part of the magnetic field does not make any contribution to the
correlator. We stress the importance of the angular resolution of the detector
in the Faraday rotation measure, showing that it could severely reduce the
effect, even for a relatively large magnetic field correlation length.


title: The dwarf galaxy population in Abell 2218

abstract:
  We present results from a deep photometric study of the rich galaxy cluster
Abell 2218 (z=0.18) based on archival HST WFPC2 F606W images. These have been
used to derive the luminosity function to extremely faint limits
(M_{F606W}=-13.2 mag, mu_{0}=24.7 mag arcsec^{-2}) over a wide field of view
(1.3 h^{-2} Mpc^2). We find the faint-end slope of the luminosity function to
vary with environment within the cluster, going from alpha=-1.23\pm0.13 within
the projected central core of the cluster (100 < r < 300 h^{-1} kpc) to
alpha=-1.49\pm 0.06 outside this radius (300 < r < 750 h^{-1} kpc). We infer
that the core is 'dwarf depleted', and further quantify this by studying the
ratio of 'dwarf' to 'giant' galaxies and its dependency as a function of
cluster-centric radius and local galaxy density. We find that this ratio varies
strongly with both quantities, and that the dwarf galaxy population in A2218
has a more extended distribution than the giant galaxy population.


title: A practical system for X-ray Interferometry

abstract:
  X-ray interferometry has the potential to provide imaging at ultra high
angular resolutions of 100 micro arc seconds or better. However, designing a
practical interferometer which fits within a reasonable envelope and that has
sufficient collecting area to deliver such a performance is a challenge. A
simple system which can be built using current X-ray optics capabilities and
existing detector technology is described. The complete instrument would be ~20
m long and ~2 m in diameter. Simulations demonstrate that it has the
sensitivity to provide high quality X-ray interferometric imaging of a large
number of available targets.


title: Halo Star Abundances and Heavy Element Nucleosynthesis

abstract:
  We present new Hubble Space Telescope (HST) abundance observations of the
neutron-capture elements Ge, Zr, Os and Pt in a group of 11 Galactic halo
stars, including the well studied r-process rich CS 22892-052 and the r-process
poor, bright giant HD 122563. Abundance comparisons indicate that the third
r-process peak elements Pt and Os seem to be correlated with Eu (obtained with
ground-based observations) in these metal-poor halo stars, suggesting a common
origin or site for these three n-capture elements.


title:
The Highly Relativistic Kiloparsec-Scale Jet of the Gamma-Ray Quasar
  0827+243

abstract:
  We present Chandra X-ray (0.2-8 keV) and Very Large Array radio (15 and 5
GHz) images of the $\gamma$-ray bright, superluminal quasar 0827+243. The X-ray
jet bends sharply--by ~90 deg., presumably amplified by projection effects--5''
from the core. Only extremely weak radio emission is detected between the
nuclear region and the bend. The X-ray continuum spectrum of the combined
emission of the knots is rather flat, with a slope of $-0.4\pm 0.2$, while the
5-15 GHz spectra are steeper for knots detected in the radio. These
characteristics, as well as non-detection of the jet in the optical band by the
Hubble Space Telescope, pose challenges to models for the spectral energy
distributions (SEDs) of the jet features. The SEDs could arise from pure
synchrotron emission from either a single or dual population of relativistic
electrons only if the minimum electron energy per unit mass $\gamma_{\min}
\gtrsim 1000$. Alternatively, the X-ray emission could result from inverse
Compton scattering of the Cosmic Microwave Background photons by electrons with
Lorentz factors as low as $\gamma \sim 15$. In all models, the bulk Lorentz
factor of the jet flow $\Gamma\gtrsim 20$ found on parsec scales must continue
without substantial deceleration out to 800 kpc (deprojected) from the nucleus.
Deceleration does appear to occur at and beyond the sharp bend, such that the
flow could be only mildly relativistic at the end of the jet.


title:
Chandra Observation of the Central Region of the Cooling Flow Cluster
  Abell 262: A Radio Source that is a Shadow of its Former Self?

abstract:
  We present a Chandra observation of the cooling flow cluster Abell 262.
Spectral fits show that the intracluster medium (ICM) in A262 cools by a factor
of three from 2.7 keV to 0.9 keV at the cluster center. A mass deposition rate
of Mdot = 19 +6/-5 Msun/yr is measured. Complex structure is found in the very
inner regions of the cluster, including knots of emission and a clear deficit
of emission to the east of the cluster center. The bright X-ray structures are
located in the same regions as optical line emission, indicating that cooling
to low temperatures has occurred in these regions. The X-ray deficit is
spatially coincident with the eastern radio lobe associated with the active
galactic nucleus hosted by the central cD galaxy. The region surrounding the
X-ray hole is cool, and shows no evidence that it has been strongly shocked.
This joins the ranks of other cooling flow clusters with Chandra-detected
bubbles blown by central radio sources. This source is different than the other
well-known cases, in that the radio source is orders of magnitude less luminous
and has produced a much smaller bubble. Comparing the energy output of the
radio source with the luminosity of the cooling gas shows that energy
transferred to the ICM from the radio source is insufficient to offset the
cooling flow unless the radio source is currently experiencing a less powerful
than average outburst, and was more powerful in the past.