title:
Near-IR observations of NGC 6822: AGB stars, distance, metallicity and
  structure

abstract:
  Observations in the IJKs wave bands covering the central 20'x20' of the Local
Group galaxy NGC 6822 have been performed from the William Herschel Telescope
in La Palma. They have allowed us to characterize, for the first time in the
near-infrared across the whole galaxy, its late-type stellar population (i.e.
red giant and asymptotic giant branch stars) and to derive from the ratio
between carbon-rich and oxygen-rich asymptotic giant branch stars an indication
about spatial variations in metallicity. These amount to about 1.89 dex, twice
of what has been previously found within each Magellanic Cloud using the same
technique. We have calibrated our photometry on the DENIS (I-band) and 2MASS (J
and Ks bands) data and obtained a distance modulus of (m-M)_0=23.34(0.12) from
the position of the tip of the RGB. The large scale distribution of late-type
stars suggests that either the galaxy lies on a strongly inclined plane or it
has a non-neglible thickness.


title:
Primordial quadrupole-induced polarisation from filamentary structures
  and galaxy clusters

abstract:
  We present the first computation of the Cosmic Microwave Background (CMB)
polarisation power spectrum from galaxy clusters and filaments using
hydrodynamical simulations of large scale structure. We give the $E$ and $B$
mode power spectra of the CMB quadrupole induced polarisation between $\ell
\sim 560$ and 20000. We find that the contribution from warm ionised gas in
filamentary structures dominates the polarised signal from galaxy clusters by
more than one order of magnitude on large scales (below $\ell \sim 1000$) and
by a factor of about two on small scales ($\ell \gsim 10000$). We study the
dependence of the power spectra with $\sigma_8$. Assuming the power spectra
vary like $\sigma_8^n$ we find $n=3.2-4.0$ for filaments and $n=3.5-4.6$ for
clusters.


title: Nonuniform Neutron-Rich Matter and Coherent Neutrino Scattering

abstract:
  Nonuniform neutron-rich matter present in both core-collapse supernovae and
neutron-star crusts is described in terms of a semiclassical model that
reproduces nuclear-matter properties and includes long-range Coulomb
interactions. The neutron-neutron correlation function and the corresponding
static structure factor are calculated from molecular dynamics simulations
involving 40,000 to 100,000 nucleons. The static structure factor describes
coherent neutrino scattering which is expected to dominate the neutrino
opacity. At low momentum transfers the static structure factor is found to be
small because of ion screening. In contrast, at intermediate momentum transfers
the static structure factor displays a large peak due to coherent scattering
from all the neutrons in a cluster. This peak moves to higher momentum
transfers and decreases in amplitude as the density increases. A large static
structure factor at zero momentum transfer, indicative of large density
fluctuations during a first-order phase transition, may increase the neutrino
opacity. However, no evidence of such an increase has been found. Therefore, it
is unlikely that the system undergoes a simple first-order phase transition. It
is found that corrections to the commonly used single heavy nucleus
approximation first appear at a density of the order of $10^{13}$ g/cm$^3$ and
increase rapidly with increasing density. Thus, neutrino opacities are
overestimated in the single heavy nucleus approximation relative to the
complete molecular dynamics simulations.


title: CMB Quadrupole induced polarisation from clusters and filaments

abstract:
  We present the estimates of the Cosmic Microwave Background (CMB)
polarisation power spectrum from galaxy clusters and filaments using
hydrodynamical simulations of large scale structure formation. We focus in the
present study on the CMB Quadrupole induced polarisation, which is the dominate
secondary polarisation effect, and give the E and B mode power spectra between
$l \sim 560$ to 20000.


title: Mm-wave HCO+, HCN and CO absorption toward NGC1052

abstract:
  We used the Plateau de Bure Interferometer to observe $\lambda$3mm J=1-0
absorption lines of \hcop, HCN and CO toward the core of the nearby elliptical,
megamaser-host galaxy NGC1052. The lines are relatively weak, with peak optical
depths 0.03 for \hcop and HCN and 0.1 for CO. Nonetheless the inferred column
density of molecular gas 2N(\HH) $\simeq 5\times10^{21}~\pcc$ is consistent
with the degree of reddening inferred toward the nucleus from observations of
the Balmer series of hydrogen. Mm-wave absorption line profiles are somewhat
broader than those of H I and OH, perhaps because lower free-free opacity at
mm-wavelengths exposes higher-velocity material nearer the nucleus. Overall,
the OH/\hcop ratio in NGC1052 is as expected from the strong relationship
established in local diffuse clouds but the optical depth ratio varies strongly
over the line profiles. Similar variations are also seen toward Cen A, which
has very different line ratios among H I, OH and \hcop for very nearly the same
amount of OH absorption.


title: H I gas in higher density regions of the intergalactic medium

abstract:
  Using H I absorption alone, we attempt to separate H I absorption lines in
quasar spectra into two categories; HDLs (Higher Density Lines) and LDLs (Lower
Density Lines), and we discuss the difference in their physical properties. We
deblend and fit all H I lines with Voigt profiles, and make an unbiased sample
of H I lines covering a wide column density range (12 < log N_HI < 19 cm^-2).
To reduce the influence of line blending, we simultaneously fit several Lyman
series lines. As a result of a two-point correlation analysis, we found that
higher column density H I lines are clustering at $\Delta$ v < 200 km/s, while
lower ones at $\Delta$ v < 100 km/s. We define HDLs as H I lines with 15 < log
N_HI < 19 cm^-2 and all H I lines within +/- 200 km/s of a line with log N_HI >
15 cm^-2, and LDLs as others with 12 < log N_HI < 15 cm^-2. We found that the
HDLs have smaller minimum b-values for a given column density than the LDLs.
This difference is successfully reproduced by our Hydrodynamic simulation. The
LDLs seem to be cool or shock-heated diffuse IGM gas, while the HDLs are likely
to be cooler dense gas near to galaxies.


title: Combined VLBI- and X-ray Observations of Active Galactic Nuclei

abstract:
  Compact radio cores in radio-loud active galactic nuclei (AGNs) are classical
targets of Very-Long-Baseline interferometric (VLBI) research. Until today
little has been known about their X-ray properties in comparison to radio-quiet
AGNs. Here, we present results from a systematic X-ray spectral survey of
radio-loud AGNs. This study is based on a statistically complete sample of
regularly monitored compact, extragalactic radio jets from the VLBA 2 cm Survey
and makes use of high-quality X-ray spectroscopic data from the archives of the
X-ray observatories ASCA, BeppoSax, CHANDRA, and XMM-Newton. Combined VLBI and
X-ray observations of AGNs can yield direct observational links between the
central parsecs of extragalactic jets and dynamical processes within the
accretion flows around supermassive black holes. It is essential to establish
such links, which might have the power to attack the unsolved problem: "What
makes an AGN radio-loud?" We present some early results from our survey project
and report briefly on detailed studies of 0716+714, NGC 1052, and 3C 390.3.


title:
Early-type galaxies in the Coma cluster: a new piece in the calcium
  puzzle

abstract:
  We present measurements of the CaII triplet and the Ca4227 Lick-index for a
sample of early-type galaxies in the Coma cluster, deriving, for the first
time, their corresponding relationships with velocity dispersion. Compared with
a similar subsample of ellipticals in the field, Coma galaxies with velocity
dispersions in the range ~ 180-270 km/s exhibit significant differences in the
strengths of the Ca features, suggesting an influence of the environment on the
star formation histories of these galaxies. We argue that the main scenarios
previously proposed to explain the relatively low CaII triplet of galaxies are
not able by themselves to simultaneously reconcile the strengths of the two Ca
indices in both environments.


title:
Multiwavelength observations of the supernova remnant G349.7+02
  interacting with a molecular cloud

abstract:
  We present molecular-line observations at millimetre, centimetre and infrared
wavelengths of the region containing OH(1720 MHz) masers in the supernova
remnant (SNR) G349.7+0.2, using the Australia Telescope (AT) Mopra antenna, the
Swedish-ESO Submillimeter Telescope, the AT Compact Array and the UNSW Infrared
Fabry-Perot narrow-band filter installed on the Anglo-Australian Telescope.
Several molecular transitions were observed between 1.6 and 3 mm to constrain
the physical parameters of the molecular cloud interacting with the SNR and to
investigate the effects of the SNR shock on the gas chemistry. We detected
shock-excited near-infrared H2 emission towards the centre of the SNR,
revealing highly clumped molecular gas and a good correlation with published
mid-infrared images from the Spitzer Space Telescope. An excellent correlation
between the H2 clumps and OH(1720 MHz) maser positions supports the shock
excitation of the OH(1720 MHz) maser emission. Furthermore, we detected OH
absorption at 1665 and 1667 MHz which shows a good correlation with the shocked
H2 emission and the masers. We found maser emission at 1665 MHz near the
OH(1720 MHz) masers in this SNR, which is found to be associated with a GLIMPSE
source SSTGLMC G349.7294+00.1747. We also detected 1665 and 1667 MHz OH masers,
and weak 4.8 GHz H2CO absorption towards the ultracompact HII region IRAS
17147-3725 located to the southeast of the SNR. We found no 4.7- or 6-GHz
excited-state OH masers or 6-GHz CH3OH maser towards either the SNR or the HII
region.


title: Diffusive Shock Acceleration of High Energy Cosmic Rays

abstract:
  The process of diffusive acceleration of charged particles in shocked plasmas
is widely invoked in astrophysics to account for the ubiquitous presence of
signatures of non-thermal relativistic electrons and ions in the universe. A
key characteristic of this statistical energization mechanism is the absence of
a momentum scale; astrophysical systems generally only impose scales at the
injection (low energy) and loss (high energy) ends of the particle spectrum.
The existence of structure in the cosmic ray spectrum (the "knee") at around
3000 TeV has promoted contentions that there are at least two origins for
cosmic rays, a galactic one supplying those up to the knee, and even beyond,
and perhaps an extragalactic one that can explain even the ultra-high energy
cosmic rays (UHECRs) seen at 1-300 EeV. Accounting for the UHECRs with familiar
astrophysical sites of acceleration has historically proven difficult due to
the need to assume high magnetic fields in order to reduce the shortest
diffusive acceleration timescale, the ion gyroperiod, to meaningful values. Yet
active galaxies and gamma-ray bursts remain strong and interesting candidate
sources for UHECRs, turning the theoretical focus to relativistic shocks. This
review summarizes properties of diffusive shock acceleration that are salient
to the issue of UHECR generation. These include spectral indices, acceleration
efficencies and timescales, as functions of the shock speed and mean field
orientation, and also the nature of the field turbulence. The interpretation of
these characteristics in the context of gamma-ray burst models for the
production of UHECRs is also examined.


title:
Weak Lensing Analysis of the z~0.8 cluster CL 0152-1357 with the
  Advanced Camera for Surveys

abstract:
  We present a weak lensing analysis of the X-ray luminous cluster CL 0152-1357
at z~0.84 using HST/ACS observations. The unparalleled resolution and
sensitivity of ACS enable us to measure weakly distorted, faint background
galaxies to the extent that the number density reaches ~175 arcmin^-2. The PSF
of ACS has a complicated shape that also varies across the field. We construct
a PSF model for ACS from an extensive investigation of 47 Tuc stars in a
modestly crowded region. We show that this model PSF excellently describes the
PSF variation pattern in the cluster observation when a slight adjustment of
ellipticity is applied. The high number density of source galaxies and the
accurate removal of the PSF effect through moment-based deconvolution allow us
to restore the dark matter distribution of the cluster in great detail. The
direct comparison of the mass map with the X-ray morphology from Chandra
observations shows that the two peaks of intracluster medium traced by X-ray
emission are lagging behind the corresponding dark matter clumps, indicative of
an on-going merger. The overall mass profile of the cluster can be well
described by an NFW profile with a scale radius of r_s =309+-45 kpc and a
concentration parameter of c=3.7+-0.5. The mass estimates from the lensing
analysis are consistent with those from X-ray and Sunyaev-Zeldovich analyses.
The predicted velocity dispersion is also in good agreement with the
spectroscopic measurement from VLT observations. In the adopted WMAP cosmology,
the total projected mass and the mass-to-light ratio within 1 Mpc are estimated
to be 4.92+-0.44 10^14 solar mass and 95+-8 solar mass/solar luminosity,
respectively.


title:
The DEEP2 Galaxy Redshift Survey: Probing the Evolution of Dark Matter
  Halos around Isolated Galaxies at z ~ 1

abstract:
  Using the first 25% of DEEP2 Redshift Survey data, we probe the line-of-sight
velocity dispersion profile for isolated galaxies with absolute B-band
magnitude -22<M_B-5log(h)<-21 at z=0.7-1.0, using satellite galaxies as
luminous tracers of the underlying velocity distribution. Measuring the
velocity dispersion beyond a galactocentric radius of ~200 kpc/h (physical)
permits us to determine the total mass, including dark matter, around these
bright galaxies. We find a line-of-sight velocity dispersion (sigma_los) of
162^{+44}_{-30} km/s at ~110 kpc/h, 136^{+26}_{-20} km/s at ~230 kpc/h, and
150^{+55}_{-38} km/s at ~320 kpc/h. Assuming an NFW model for the dark matter
density profile, this corresponds to a mass within r_{200} of
M_200=5.5^{+2.5}_{-2.0} x 10^12 M_Sun/h for our sample of satellite hosts with
mean luminosity ~2.5L*. Roughly $~60% of these host galaxies have early-type
spectra and are red in restframe (U-B) color, consistent with the overall DEEP2
sample in the same luminosity and redshift range. The halo mass determined for
DEEP2 host galaxies is consistent with that measured in the Sloan Digital Sky
Survey for host galaxies within a similar luminosity range relative to M*_B.
This comparison is insensitive to the assumed halo mass profile, and implies an
increase in the dynamical mass-to-light ratio (M_200/L_B) of isolated galaxies
which host satellites by a factor of ~2.5 from z ~ 1 to z ~ 0. Our results are
consistent with scenarios in which galaxies populate dark matter halos
similarly from z ~ 0 to z ~ 1, except for ~1 magnitude of evolution in the
luminosity of all galaxies.


title: Observations of Gamma-Ray Outbursts from Galactic Microquasars

abstract:
  The BATSE earth-occultation database provides nine years of coverage for 75
$\gamma$-ray sources in the energy range 35-1700 keV. For transient sources,
this long time-base dataset makes it possible to study the repeated outbursts
from individual objects. We have used the JPL data analysis package EBOP
(Enhanced BATSE Occultation Package) to derive the light curves and the time
evolution of the spectra for the black hole candidate and microquasar sources
GRO J1655-40 and GRS 1915+105. We find that GRO J1655-40, during high-intensity
flaring periods, is characterized by a single power-law spectrum up to 500 keV
with a spectral index consistent with that observed by OSSE. During one flare
observed contemporaneously with OSSE and HEXTE, the GRO J1655-40 spectrum was
observed to steepen as the $\gamma$-ray intensity increased. For GRS 1915+105,
the spectrum during high intensity flaring periods can be characterized by a
broken power law with a time-varying high-energy component. The spectra of
these microquasars differ from the black hole candidates Cygnus X-1, GRO
J0422+32, and GRO J1719-24, which have thermal contributions to their spectra
when in high $\gamma$-ray states. This suggests that there may be two different
classes of Galactic black hole candidates.


title:
Gamma-Ray Spectral Characteristics of Thermal and Non-Thermal Emission
  from Three Black Holes

abstract:
  Cygnus X-1 and the gamma-ray transients GROJ0422+32 and GROJ1719-24 displayed
similar spectral properties when they underwent transitions between the high
and low gamma-ray (30 keV to few MeV) intensity states. When these sources were
in the high gamma-ray intensity state (gamma-2, for Cygnus X-1), their spectra
featured two components: a Comptonized shape below 200-300 keV with a soft
power-law tail (photon index >3) that extended to ~1 MeV or beyond. When the
sources were in the low-intensity state (gamma-0, for Cygnus X-1), the
Comptonized spectral shape below 200 keV typically vanished and the entire
spectrum from 30 keV to ~1 MeV can be characterized by a single power law with
a relatively harder photon index ~2-2.7. Consequently the high- and
low-intensity gamma-ray spectra intersect, generally in the ~400 keV - 1 MeV
range, in contrast to the spectral pivoting seen previously at lower (~10 keV)
energies. The presence of the power-law component in both the high- and
low-intensity gamma-ray spectra strongly suggests that the non-thermal process
is likely to be at work in both the high and the low-intensity situations. We
have suggested a possible scenario (Ling & Wheaton, 2003), by combining the
ADAF model of Esin et al. (1998) with a separate jet region that produces the
non-thermal gamma-ray emission, and which explains the state transitions. Such
a scenario will be discussed in the context of the observational evidence,
summarized above, from the database produced by EBOP, JPL's BATSE earth
occultation analysis system.


title: A New Probe of the Planet-Forming Region in T Tauri Disks

abstract:
  We present new observations of the FUV (1100-2200 Angstrom) radiation field
and the near- to mid-IR (3--13.5 micron) spectral energy distribution (SED) of
a sample of T Tauri stars selected on the basis of bright molecular disks (GM
Aur, DM Tau, LkCa15). In each source we find evidence for Ly alpha induced H2
fluorescence and an additional source of FUV continuum emission below 1700
Angstroms. Comparison of the FUV spectra to a model of H2 excitation suggests
that the strong continuum emission is due to electron impact excitation of H2.
The ultimate source of this excitation is likely X-ray irradiation which
creates hot photo-electrons mixed in the molecular layer. Analysis of the SED
of each object finds the presence of inner disk gaps with sizes of a few AU in
each of these young (~1 Myr) stellar systems. We propose that the presence of
strong H2 continuum emission and inner disk clearing are related by the
increased penetration power of high energy photons in gas rich regions with low
grain opacity.


title:
High-Energy Processes in Young Stars: Chandra X-ray Spectroscopy of HDE
  283572, RY Tau, and LkCa 21

abstract:
  Weak-lined T Tauri stars (WTTS) represent the important stage of stellar
evolution between the accretion phase and the zero-age main sequence. At this
stage, the star decouples from its accretion disk, and spins up to a higher
rotation rate than in the preceding classical T Tauri phase. Consequently,
dynamo processes can be expected to become even stronger at this stage. High
energy processes can have effects on the remaining circumstellar material,
possibly including protoplanets and planetesimals, and these effects may
account for certain observable properties of asteroids in the current solar
system. Chandra observed for 100 ks the WTTS HDE 283572 which probes the PMS
stage of massive A-type stars. We present first results of the analysis of its
high-resolution X-ray spectrum obtained with the High-Energy Transmission
Grating Spectrometer. A wide range of Fe lines of high ionization states are
observed, indicating a continuous emission measure distribution. No significant
signal is detected longward of the O \textsc{viii} Ly$\alpha$ line because of
the high photoelectric absorption. We also report on the preliminary analysis
of the zeroth order spectra of RY Tau and LkCa21. In particular, we show
evidence of an emission line in RY Tau at 6.4 keV that we identify as
fluorescent emission by neutral Fe caused by a strong X-ray flare which
illuminated some structure in (or surrounding) the CTTS. A comparison of X-ray
spectra of classical T Tau stars, other WTTS, and young main-sequence stars is
made.


title:
Searching for high-redshift centimeter-wave continuum, line and maser
  emission using the Square Kilometer Array

abstract:
  We discuss the detection of redshifted line and continuum emission at radio
wavelengths using a Square Kilometer Array (SKA), specifically from
low-excitation rotational molecular line transitions of CO and HCN (molecular
lines), the recombination radiation from atomic transitions in almost-ionized
hydrogen (radio recombination lines; RRLs), OH and water maser lines, as well
as from synchrotron and free-free continuum radiation and HI 21-cm line
radiation. The detection of radio lines with the SKA offers the prospect to
determine the redshifts and thus exact luminosities for some of the most
distant and optically faint star-forming galaxies and active galactic nuclei
(AGN), even those galaxies that are either deeply enshrouded in interstellar
dust or shining prior to the end of reionization. Moreover, it provides an
opportunity to study the astrophysical conditions and resolved morphologies of
the most active regions in galaxies during the most active phase of star
formation at redshift z~2. A sufficiently powerful and adaptable SKA correlator
will enable wide-field three-dimensional redshift surveys at chosen specific
high redshifts, and will allow new probes of the evolution of large-scale
structure (LSS) in the distribution of galaxies. The detection of molecular
line radiation favours pushing the operating frequencies of SKA up to at least
26 GHz, and ideally to 40 GHz, while very high redshift maser emissions
requires access to about 100 MHz. To search for LSS the widest possible
instantaneous field of view would be advantageous.


title:
Observations of HI 21cm absorption by the neutral IGM during the epoch
  of re-ionization with the Square Kilometer Array

abstract:
  We explore the possibility of detecting HI 21cm absorption by the neutral
intergalactic medium (IGM) toward very high redshift radio sources, and by gas
associated with the first collapsed structures, using the Square Kilometer
Array at low frequency (100 to 200 MHz). The epoch considered is between the
time when the first ionizing sources form and when the bulk of the neutral IGM
becomes ionized. Expected IGM absorption signal includes $\sim 1%$ absorption
by the mean neutral IGM (the radio 'Gunn-Peterson' effect'), plus deeper,
narrow lines ($\ge 5%$, a few km s$^{-1}$) arising in mild density
inhomogeneities with typical values of cosmic overdensity $\delta\sim 10$,
precisely the structures that at later times give rise to the Ly$\alpha$ forest
(the `21cm forest'). Absorption can also arise in gas associated with collapsed
structures ($\delta\ge 100$), including 'minihalos' ($\le 10^7$ M$_\odot$) and
protodisks ($\ge 10^8$ M$_\odot$). We consider SKA sensitivity limits and the
evolution of radio source populations, and conclude that it is reasonable to
hypothesize the existence of an adequate number of high-$z$ radio sources
against which such absorption studies could be performed, provided that
reionization occurs at $z < 10$. Lastly, we discuss the possibility of `line
confusion' due to radio recombination lines arising in the ionized IGM.


title: Probing the Dark Ages with the Square Kilometer Array

abstract:
  The epoch of reionization (EoR) sets a fundamental benchmark in cosmic
structure formation, corresponding to the formation of the first luminous
objects that act to ionize the neutral intergalactic medium (IGM). Recent
observations at near-IR and radio wavelengths imply that we are finally probing
into this key epoch of galaxy formation at $z \ge 6$. The Square Kilometer
Array (SKA) will provide critical insight into the EoR in a number of ways.
First, the ability of the SKA to image the neutral IGM in 21cm emission is a
truly unique probe of the process of reionization, and is recognized as the
next necessary and fundamental step in our study of the evolution of large
scale structure and cosmic reionization. Second, study of HI 21cm absorption
toward the first radio loud objects probes small to intermediate scale
structure in the neutral 'cosmic web', as well as HI in the first collapsed
structures (proto-disks and mini-halos). And third, the incomparable
sensitivity of the SKA allows for the study of the molecular gas, dust, and
star formation activity in the first galaxies, as well as the radio continuum
emission from the first accreting massive black holes. Such objects will be
obscured at optical wavelengths due to absorption by the neutral IGM.


title:
Ages and metallicities of star clusters: new calibrations and diagnostic
  diagrams from visible integrated spectra

abstract:
  We present homogeneous scales of ages and metallicities for star clusters
from very young objects, through intermediate-age ones up to the oldest known
clusters. All the selected clusters have integrated spectra in the visible
range, as well as reliable determinations of their ages and metallicities. From
these spectra equivalent widths (EWs) of KCaII, Gband(CH) and MgI metallic, and
Hdelta, Hgamma and Hbeta Balmer lines have been measured homogeneously. The
analysis of these EWs shows that the EW sums of the metallic and Balmer H
lines, separately, are good indicators of cluster age for objects younger than
10 Gyr, and that the former is also sensitive to cluster metallicity for ages
greater than 10 Gyr. We propose an iterative procedure for estimating cluster
ages by employing two new diagnostic diagrams and age calibrations based on the
above EW sums. For clusters older than 10 Gyr, we also provide a calibration to
derive their overall metal contents.


title:
The 2dF QSO Redshift Survey - XIV. Structure and evolution from the
  two-point correlation function

abstract:
  We present a clustering analysis of QSOs using over 20000 objects from the
final catalogue of the 2dF QSO Redshift Survey (2QZ), measuring the z-space
correlation function, xi(s). When averaged over the range 0.3<z<2.2 we find
that xi(s) is flat on small scales, steepening on scales above ~25h-1Mpc. In a
WMAP/2dF cosmology we find a best fit power law with s_0=5.48+0.42-0.48h-1Mpc
and gamma=1.20+-0.10 on scales s=1-25h-1Mpc. A CDM model assuming WMAP/2dF
cosmological parameters is a good description of the QSO xi(s) after accounting
for non-linear clustering and z-space distortions, and a linear bias of
b_qso(z=1.35)=2.02+-0.07. We subdivide the 2QZ into 10 redshift intervals from
z=0.53 to 2.48 and find a significant increase in clustering amplitude at high
redshift in the WMAP/2dF cosmology. We derive the bias of the QSOs which is a
strong function of redshift with b_qso(z=0.53)=1.13+-0.18 and
b_qso(z=2.48)=4.24+-0.53. We use these bias values to derive the mean dark
matter halo (DMH) mass occupied by the QSOs. At all redshifts 2QZ QSOs inhabit
approximately the same mass DMHs with M_DH=(3.0+-1.6)x10^12h-1M_sun, which is
close to the characteristic mass in the Press-Schechter mass function, M*, at
z=0. If the relation between black hole (BH) mass and M_DH or host velocity
dispersion does not evolve, then we find that the accretion efficiency
(L/L_edd) for L* QSOs is approximately constant with redshift. Thus the fading
of the QSO population from z~2 to 0 appears to be due to less massive BHs being
active at low redshift. We apply different methods to estimate, t_qso, the
active lifetime of QSOs and constrain this to be in the range 4x10^6-6x10^8
years at z~2. (Abridged).


title:
Grain growth and dust settling in a brown dwarf disk: Gemini/T-ReCS
  observations of CFHT-BD-Tau 4

abstract:
  We present accurate mid-infrared observations of the disk around the young,
bona-fide brown dwarf CFHT-BD-Tau 4. We report GEMINI/T-ReCS measurements in
the 7.9, 10.4 and 12.3 micron filters, from which we infer the presence of a
prominent, broad silicate emission feature. The shape of the silicate feature
is dominated by emission from 2 micron amorphous olivine grains. Such grains,
being an order of magnitude larger than those in the interstellar medium, are a
first proof of dust processing and grain growth in disks around brown dwarfs.
The object's spectral energy distribution is below the prediction of the
classical flared disk model but higher than that of the two-layer flat disk. A
good match can be achieved by using an intermediate disk model with strongly
reduced but non-zero flaring. Grain growth and dust settling processes provide
a natural explanation for this disk geometry and we argue that such
intermediate flaring might explain the observations of several other brown
dwarf disks as well.


title: Cosmogenic Neutrinos from Ultra-High Energy Nuclei

abstract:
  We calculate the flux of neutrinos generated by the propagation of ultra-high
energy iron over cosmological distances and show that even if ultra-high energy
cosmic rays are composed of heavy nuclei, a significant flux of high-energy
neutrinos should be present throughout the universe. The resulting neutrino
flux has a new peak at $\sim 10^{14} eV$ generated by neutron decay and
reproduces the double peak structure due to photopion production at higher
energies ($\sim 10^{18}$ eV). Depending on the maximum energy and cosmological
evolution of extremely high energy cosmic accelerators the generated neutrino
flux can be detected by future experiments.


title:
Kinematics of Vega-like stars: lifetimes and temporal evolution of
  circumstellar dust disks

abstract:
  We have used the velocity dispersion as an age indicator to constrain the
ages of a large sample of main sequence Vega-like stars in order to study the
lifetimes and temporal evolution of the dust disks around them. We use
HIPPARCOS measurements to compute stellar velocities in the sky plane. The
velocity dispersion of Vega-like stars is found to be systematically smaller
than that of the normal main sequence field stars for all spectral types,
suggesting that the main sequence dusty systems, on average, are younger than
normal field stars. The debris disks seem to survive longer around late type
stars as compared to early type stars. Further, we find a strong correlation
between fractional dust luminosity ((f_{d} \equiv L_{dust}/L_{\star})) and
velocity dispersion of stars with dust disks. Fractional dust luminosity is
found to drop off steadily with increasing stellar age from early pre-main
sequence phase to late main sequence phase.


title:
Probing The Multiphase Interstellar Medium Of The Dwarf Starburst Galaxy
  NGC 625 With FUSE Spectroscopy

abstract:
  We present new FUSE spectroscopy of the dwarf starburst galaxy NGC 625. These
observations probe multiple phases of the interstellar medium, including the
coronal, ionized, neutral and molecular gas. This nearby (D = 3.9 +/- 0.2 Mpc)
system shows a clear detection of outflowing coronal gas as traced by OVI 1032
Angstrom absorption. The centroid of the OVI profile is blueshifted with
respect to the galaxy systemic velocity by ~ 30 km/sec, suggesting a
low-velocity outflow. The implied OVI velocity extent is found to be 100 +/- 20
km/sec, which is fully consistent with the detected HI outflow velocity found
in radio synthesis observations. We detect multiple lines of diffuse H2
absorption from the ISM of NGC 625; this is one of only a few extragalactic
systems with FUSE detections of H2 lines in the Lyman and Werner bands. We find
a potential abundance offset between the neutral and nebular gas that exceeds
the errors on the derived column densities. Since such an offset has been found
in multiple dwarf galaxies, we discuss the implications of a lower-metallicity
halo surrounding the central star forming regions of dwarf galaxies. The
apparent offset may be due to saturation of the observed OI line, and higher
S/N observations are required to resolve this issue.


title: The KASCADE-Grande Experiment and the LOPES Project

abstract:
  KASCADE-Grande is the extension of the multi-detector setup KASCADE to cover
a primary cosmic ray energy range from 100 TeV to 1 EeV. The enlarged EAS
experiment provides comprehensive observations of cosmic rays in the energy
region around the knee. Grande is an array of 700 x 700 sqm equipped with 37
plastic scintillator stations sensitive to measure energy deposits and arrival
times of air shower particles. LOPES is a small radio antenna array to operate
in conjunction with KASCADE-Grande in order to calibrate the radio emission
from cosmic ray air showers. Status and capabilities of the KASCADE-Grande
experiment and the LOPES project are presented.


title: Galaxy-galaxy lensing studies from COMBO-17

abstract:
  We study the dark matter halos of galaxies with galaxy-galaxy lensing using
the COMBO-17 survey. This survey offers an unprecedented data set for studying
lens galaxies at z=0.2-0.7 including redshift information and spectral
classification from 17 optical filters for objects brighter than R=24. So far,
redshifts and classification for the lens galaxies have mainly been available
for local surveys like the Sloan Digital Sky Survey (SDSS). Further, redshifts
for the source galaxies have typically not been available at all but had to be
estimated from redshift probability distribution which -- for faint surveys --
even had to be extrapolated.
  To study the dark matter halos we parametrize the lens galaxies as singular
isothermal spheres (SIS) or by Navarro-Frenk-White (NFW) profiles. In both
cases we find a dependence of the velocity dispersion or virial radius,
respectively, on lens luminosity and colour. For the SIS model, we are able to
reproduce the Tully-Fisher/Faber-Jackson relation on a scale of 150h^-1kpc. For
the NFW profile we also calculate virial masses, mass-to-light ratios and
rotation velocities.
  Finally, we investigate differences between the three survey fields used
here.


title: Radio sources at low Galactic latitudes

abstract:
  We present high-resolution radio observations of a sample of 65 radio sources
at low Galactic latitudes. The sources were all observed at 5 GHz with the Very
Large Array A-array. MERLIN observations at 5 GHz of the ultracompact HII
region G34.26+0.15 and one of the extragalactic sources, B1857-000, are also
presented, as are GMRT observations of HI in the direction of three sources,
B1801-203, B1802-196 and B1938+229. These observations were made with the
objectives of (i) finding compact components suitable for studying the effects
of interstellar scattering at lower frequencies, (ii) identifying high
surface-brightness lobes of background radio sources to probe the Galactic
magnetic field on different scales via polarization observations, and (iii)
searching for young supernova remnants. We discuss the nature of the sources
found to have shell or shell-like structure and exhibiting both thermal and
non-thermal spectra. Of the remaining sources, B1749-281 is coincident within
the positional errors of a known pulsar, not detected earlier at 5 GHz. The
rest are likely to be background extragalactic objects.


title: Strong lensing analysis of A1689 from deep ACS images

abstract:
  ACS observations of massive lensing clusters permit an order of magnitude
increase in the numbers of multiply-lensed background galaxies identified
behind a given cluster. We have developed a code to take the pixels belonging
to any given image and generate counter-images with full resolution, so that
multiple systems are convincingly and exhaustively identified. Over 130 images
of 35 multiply lensed galaxies are found behind A1689, including many radial
arcs and also tiny counter-images projected on the center of mass. The derived
mass profile is found to flatten steadily towards the center, like an NFW
profile, with a mean slope d(log(Sigma))/d(log(r)) ~ -0.55 +/- 0.1, over the
range r<250 kpc/h, which is somewhat steeper than predicted for such a massive
halo. We also clearly see the expected geometric increase of bend angles with
redshift, however, given the low redshift of A1689, z=0.18, the dependence on
cosmological parameters is weak, but using higher redshift clusters from our
GTO program we may derive a more competitive constraint.


title: A Giant Planet Candidate near a Young Brown Dwarf

abstract:
  We present deep VLT/NACO infrared imaging and spectroscopic observations of
the brown dwarf 2MASSWJ1207334-393254, obtained during our on-going adaptive
optics survey of southern young, nearby associations. This 25 MJup brown dwarf,
located 70 pc from Earth, has been recently identified as a member of the TW
Hydrae Association (age 8 Myr). Using adaptive optics infrared wavefront
sensing to acquire sharp images of its circumstellar environment, we discovered
a very faint and very red object at a close separation of 780 mas (55 AU).
Photometry in the H, Ks and L' bands and upper limit in J-band are compatible
with a spectral type L5-L9.5. Near-infrared spectroscopy is consistent with
this spectral type estimate. Different evolutionary models predict an object
within the planetary regime with a mass of 5+-2 MJup and an effective
temperature of Teff=1250+-200K.


title:
Effect of local treatments of convection upon the solar p-mode
  excitation rates

abstract:
  We compute, for several solar models, the rates P at which the solar radial p
modes are expected to be excited. The solar models are computed with two
different local treatments of convection : the classical mixing-length theory
(MLT hereafter) and Canuto, Goldmann and Mazzitelli(1996, CGM hereafter)'s
formulation. For one set of solar models (EMLT and ECGM models), the atmosphere
is gray and assumes Eddington's approximation. For a second set of models (KMLT
and KCGM models), the atmosphere is built using a T(tau) law which has been
obtained from a Kurucz's model atmosphere computed with the same local
treatment of convection. The mixing-length parameter in the model atmosphere is
chosen so as to provide a good agreement between synthetic and observed Balmer
line profiles, while the mixing-length parameter in the interior model is
calibrated so that the model reproduces the solar radius at solar age. For the
MLT treatment, the rates P do depend significantly on the properties of the
atmosphere. On the other hand, for the CGM treatment, differences in P between
the ECGM and the KCGM models are very small compared to the error bars attached
to the seismic measurements. The excitation rates P for modes from the EMLT
model are significantly under-estimated compared with the solar seismic
constraints. The KMLT model results in intermediate values for P and shows also
an important discontinuity in the temperature gradient and the convective
velocity. On the other hand, the KCGM model and the ECGM model yield values for
P closer to the seismic data than the EMLT and KMLT models. We conclude that
the solar p-mode excitation rates provide valuable constraints and according to
the present investigation cleary favor the CGM treatment with respect to the
MLT.


title:
Oscillation power spectra of the Sun and of Alpha Cen A: observations
  versus models

abstract:
  Hydrodynamical, 3D simulations of the outer layers of the Sun and Alpha Cen A
are used to obtain constraints on the properties of turbulent convection in
such stars. These constraints enable us to compute - on the base of a
theoretical model of stochastic excitation - the rate P at which p modes are
excited by turbulent convection in those two stars. Results are then compared
with solar seismic observations and recent observations of Alpha Cen A. For the
Sun, a good agreement between observations and computed P is obtained. For
Alpha Cen A a large discrepancy is obtained which origin cannot be yet
identified: it can either be caused by the present data quality which is not
sufficient for our purpose or by the way the intrinsic amplitudes and the
life-times of the modes are determined or finally attributed to our present
modelling. Nevertheless, data with higher quality or/and more adapted data
reductions will likely provide constraints on the p-mode excitation mechanism
in Alpha Cen A.


title:
Bounds on CDM and neutrino isocurvature perturbations from CMB and LSS
  data

abstract:
  Generic models for the origin of structure predict a spectrum of initial
fluctuations with a mixture of adiabatic and isocurvature perturbations. Using
the observed anisotropies of the cosmic microwave backgound, the matter power
spectra from large scale structure surveys and the luminosity distance vs
redshift relation from supernovae of type Ia, we obtain strong bounds on the
possible cold dark matter/baryon as well as neutrino isocurvature contributions
to the primordial fluctations in the Universe. Neglecting the possible effects
of spatial curvature and tensor perturbations, we perform a Bayesian likelihood
analysis with thirteen free parameters, including independent spectral indexes
for each of the modes and for their cross-correlation angle. We find that
around a pivot wavenumber of k=0.05 h/Mpc the amplitude of the correlated
isocurvature component cannot be larger than about 60% for the cold dark matter
mode, 40% for the neutrino density mode, and 30% for the neutrino velocity
mode, at 2 sigma. In the first case, our bound is larger than the WMAP
first-year result, presumably because we prefer not to include any data from
Lyman-alpha forests, but then obtain large blue spectral indexes for the
non-adiabatic contributions. We also translate our bounds in terms of
constraints on double inflation models with two uncoupled massive fields.


title: The 0.03-10Mo mass function of young open clusters

abstract:
  We report the present day mass functions (PDMFs) of 3 young open clusters
over a mass range from 30 Jupiter masses to 10~\msunn. The PDMFs of the 3
clusters are remarkably similar, suggesting little impact of specific
conditions (stellar density, metallicity, early dynamical evolution) on the
mass distribution. Functional forms are provided to allow quantitative
comparison with MFs derived in other environments.


title: Millimetre-VLBI Monitoring of AGN with Sub-milliarcsecond Resolution

abstract:
  Global millimetre VLBI allows detailed studies of the most central jet
regions of AGN with unprecedent spatial resolution of a few 100-1000
Schwartzschild radii to be made. Study of these regions will help to answer the
question how the highly relativistic AGN jets are launched and collimated.
Since the early 1990s, bright mm-sources have been observed with global 3 mm
VLBI. Here we present new images from an ongoing systematic analysis of the
available observations. In particular, we focus on the structure and structural
evolution of the best observed AGN jets, taking 3C 454.3 as a characteristic
example. This core-dominated and highly variable quasar shows a complex
morphology with individual jet components accelerating superluminally towards
the outer structure. We briefly discuss the X-ray properties of 3C 454.3 and
present its radio- to X-ray large-scale brightness distribution.


title: HI deficiency in groups : what can we learn from Eridanus

abstract:
  The HI content of the Eridanus group of galaxies is studied using the GMRT
observations and the HIPASS data. A significant HI deficiency up to a factor of
2-3 is observed in galaxies in the Eridanus group. The deficiency is found to
be directly correlated with the projected galaxy density and inversely
correlated with the line-of-sight radial velocity. It is suggested that the HI
deficiency is due to tidal interactions. An important implication is that
significant evolution of galaxies can take place in a group environment.


title: Spectral Properties of the Core and the VLBI-Jets of Cygnus A

abstract:
  We present a detailed VLBI study of the spectral properties of the inner core
region of the radio galaxy Cygnus A at 5 GHz, 15 GHz, 22 GHz, 43 GHz and 86
GHz. Our observations include an epoch using phase-referencing at 15 GHz and 22
GHz and the first successful VLBI observations of Cygnus A at 86 GHz. We find a
pronounced two-sided jet structure, with a steep spectrum along the jet and an
inverted spectrum towards the counter-jet. The inverted spectrum and the
frequency-dependent jet-to-counter-jet ratio suggest that the inner counter-jet
is covered by a circum-nuclear absorber as it is proposed by the unified
scheme.


title:
Probing General Relativity With Mergers of Supermassive and
  Intermediate-Mass Black Holes

abstract:
  Recent observations and stellar dynamics simulations suggest that thousand
solar mass black holes can form in compact massive young star clusters. Any
such clusters in the bulge of their host galaxy will spiral to the center
within a few hundred million years, where their intermediate-mass black holes
are likely to merge eventually with the galaxy's supermassive black hole. If
such mergers are common, then future space-based gravitational wave detectors
such as the Laser Interferometer Space Antenna will detect them with such a
high signal to noise ratio that towards the end of the inspiral the orbits will
be visible in a simple power density spectrum, without the need for matched
filtering. We discuss the astrophysics of the inspiral of clusters in the
nuclear region of a galaxy and the subsequent merger of intermediate-mass with
supermassive black holes. We also examine the prospects for understanding the
spacetime geometry of rotating black holes, based on phase connection of the
strong signals visible near the end of these extreme mass ratio inspirals.


title: The Shaping of the Red Rectangle Proto-Planetary Nebula

abstract:
  I argue that the slowly expanding biconical structure of the Red Rectangle--a
nebula around the post asymptotic giant branch binary stellar system HD
44179--can be formed by intermittent jets blown by the accreting companion. The
bright biconical structure of the Red Rectangle nebula can be understood to be
composed of a multiple double-ring system. In the proposed shaping process, one
among several processes through which a companion can shape the circumbinary
gas, the companion accretes mass from the slow wind blown by the evolved mass
losing star. An accretion disk is formed, and if mass accretion is larger than
a critical value, two jets, or a collimated fast wind (CFW) are blown. If the
high mass loss rate duration is long, bipolar lobes are formed. If, on the
other hand, mass loss rate is intermittent, and during one orbital period the
slow wind fills a region which does not extend much beyond the binary system,
then only a fraction of the double-lobe structure is formed, namely, rings.
This, I propose, was the case with the progenitor of the Red Rectangle, where
intermittent episodes of enhanced mass loss rate led to the formation of a
multiple double-ring system.


title: A search for very young Planetary Nebulae

abstract:
  Despite numerous efforts, the transition from Asymptotic Giant Branch (AGB)
stars to Planetary Nebulae (PN) is a poorly understood phase of stellar
evolution. We have therefore carried out interferometric (VLA) radio
observations of a sample of hot post-AGB stars, selected on the basis of their
optical and infrared properties. Ten sources out of the 16 observed were
detected. This indicates that most of our targets are surrounded by a nebula
where the ionization has already started. This definitively determines the
evolutionary status of the selected sources and provides us with a unique
sample of very young Planetary Nebulae (yPNe). A comparison with another sample
of yPNe confirms our working hypothesis that our targets are indeed very young,
probably just in the transition toward PN. Finding transition objects is
extremely important as they can provide unique clues for a better understanding
of this important phase of stellar evolution.


title: ISO observations of the Galactic center Interstellar Medium: ionized gas

abstract:
  (Abridged) We present fine structure and recombination lines observations of
the ionized gas toward a sample of 18 sources located within 300 pc of the
center of the Galaxy (GC). The fine structure lines from [NII] and [SIII] have
been detected in 16 sources. In 10 sources we have even detected the [OIII] 88
$\mu$m line. The measured N, S and Ne abundances are similar to those measured
in the HII regions in the 5-kpc ring and in the nuclei of starburst galaxies.
The fine structure lines ratios measured for all the sources can be explained
by photo-ionization with an effective temperature of 32000-37000 K and an
ionization parameter, $U$, of $-1>\log U > -3$. The highest excitation is found
in the Radio Arc region but there must be more ionizing sources distributed
over the Galactic center than the known clusters of massive stars. Most of the
clouds are located far from the prominent continuum complexes (Sgr C, B ...).
However, it is possible that the clouds are ionized by escaped photons from
those complexes. The excitation ratios, effective temperature and ionization
parameter measured in the GC are similar to those found in some low excitation
starburst galaxies. The [NeIII]/[NeII] line ratios measured in the GC sources
are consistent with the results of the Thornely et al. (2000) model for a short
burst of massive star formation less than 8 Myr ago. We have also found that
the [NeII] 13 $\mu$m ~ to far-infrared continuum ratio measured for the GC
sources is similar to that of external galaxies, supporting the idea by Sturm
et al. (2002) that the far-infrared continuum in Active Galaxies is dominated
by dust heated by stellar radiation rather than by the AGN.


title: Multiple Companions to HD 154857 and HD 160691

abstract:
  Precise Doppler measurements from the AAT/UCLES spectrometer reveal two
companions to both HD 154857 and HD 160691. The inner companion to HD 154857
has a period of 398 d, an eccentricity of 0.51, and a minimum mass of 1.8
M_Jupiter An outer companion has a period much longer than 2 years and is
currently detected only as a linear trend of 14 m/s per year. The inner
companion to HD 160691, previously announced from AAT data, has a period of 645
d, an eccentricity of 0.20, and a minimum mass of 1.7 M_Jupiter. For the outer
planet, whose orbit is less well constrained, a two Keplerian fit yields a
period of 8.2 yr, an eccentricity of 0.57, and a minimum mass of 3.1 M_Jupiter.
With these orbital parameters, its maximum separation from the star of 0.4
arcsec makes it a viable target for direct imaging.


title: Determination of confusion noise for far-infrared measurements

abstract:
  We present a detailed assessment of the far-infrared confusion noise imposed
on measurements with the ISOPHOT far-infrared detectors and cameras aboard the
ISO satellite. We provide confusion noise values for all measurement
configurations and observing modes of ISOPHOT in the 90<=lambda<=200um
wavelength range. Based on these results we also give estimates for cirrus
confusion noise levels at the resolution limits of current and future
instruments of infrared space telescopes: Spitzer/MIPS, ASTRO-F/FIS and
Herschel/PACS.


title:
Hard X-ray emitting Active Galactic Nuclei selected by the Chandra
  Multi-wavelength Project

abstract:
  We present X-ray and optical analysis of 188 AGN identified from 497 hard
X-ray (f (2.0-8.0 keV) > 2.7x10^-15 erg cm^-2 s^-1) sources in 20 Chandra
fields (1.5 deg^2) forming part of the Chandra Multi-wavelength Project. These
medium depth X-ray observations enable us to detect a representative subset of
those sources responsible for the bulk of the 2-8 keV Cosmic X-ray Background.
Brighter than our optical spectroscopic limit, we achieve a reasonable degree
of completeness (77% of X-ray sources with counter-parts r'< 22.5 have been
classified): broad emission line AGN (62%), narrow emission line galaxies
(24%), absorption line galaxies (7%), stars (5%) or clusters (2%). We find that
most X-ray unabsorbed AGN (NH<10^22 cm^-2) have optical properties
characterized by broad emission lines and blue colors, similiar to
optically-selected quasars from the Sloan Digital Sky Survey but with a slighly
broader color distribution. However, we also find a significant population of
redder (g'-i'>1.0) AGN with broad optical emission lines. Most of the X-ray
absorbed AGN (10^22<NH<10^24 cm^-2) are associated with narrow emission line
galaxies, with red optical colors characteristically dominated by luminous,
early type galaxy hosts rather than from dust reddening of an AGN. We also find
a number of atypical AGN; for instance, several luminous AGN show both strong
X-ray absorption (NH>10^22 cm^-2) and broad emission lines. Overall, we find
that 81% of X-ray selected AGN can be easily interpreted in the context of
current AGN unification models. Most of the deviations seem to be due to an
optical contribution from the host galaxies of the low luminosity AGN.


title: The late-time light curve of the Type Ia supernova 2000cx

abstract:
  We have conducted a systematic and comprehensive monitoring programme of the
Type Ia supernova 2000cx at late phases using the VLT and HST. The VLT
observations cover phases 360 to 480 days past maximum brightness and include
photometry in the BVRIJH bands, together with a single epoch in each of U and
Ks. While the optical bands decay by about 1.4 mag per 100 days, we find that
the near-IR magnitudes stay virtually constant during the observed period. This
means that the importance of the near-IR to the bolometric light curve
increases with time. The finding is also in agreement with our detailed
modeling of a Type Ia supernova in the nebular phase. In these models, the
increased importance of the near-IR is a temperature effect. We note that this
complicates late-time studies where often only the V band is well monitored. In
particular, it is not correct to assume that any optical band follows the
bolometric light curve at these phases, and any conclusions based on such
assumptions, e.g., regarding positron-escape, must be regarded as premature. A
very simple model where all positrons are trapped can reasonably well account
for the observations. The nickel mass deduced from the positron tail of this
light curve is lower than found from the peak brightness, providing an estimate
of the fraction of late-time emission that is outside of the observed
wavelength range. Our detailed models show the signature of an infrared
catastrophe at these epochs, which is not supported by the observations.


title: Faraday screens associated with local molecular clouds

abstract:
  Polarization observations at 21cm and 18cm towards the local Taurus molecular
cloud complex were made with the Effelsberg 100-m telescope. Highly structured,
frequency-dependent polarized emission features were detected. We discuss
polarization minima with excessive rotation measures located at the boundaries
of molecular clouds. The multi-frequency polarization data have been
successfully modeled by considering magneto-ionic Faraday screens at the
surface of the molecular clouds. Faraday rotated background emission adds to
foreground emission towards these screens in a different way than in its
surroundings. The physical size of the Faraday screens is of the order of 2 pc
for 140 pc distance to the Taurus clouds. Intrinsic rotation measures between
about -18 rad/m2 to -30 rad/m2 are required to model the observations.
Depolarization of the background emission is quite small (compatible with
zero), indicating a regular magnetic field structure with little turbulence
within the Faraday screens. With observational constraints for the thermal
electron density from H-alpha observations of less than 0.8 cm^-3 we conclude
that the regular magnetic field strength along the line of sight exceeds 20
muG. We discuss some possibilities for the origin of such strong and well
ordered magnetic fields. The modeling also predicts a large-scale, regularly
polarized emission in the foreground of the Taurus clouds which is of the order
of 0.24 K at 21cm. This amount of synchrotron emission is clearly excessive
when compared to previous estimates of the local synchrotron emissivity.


title: Diffuse Interstellar Bands in NGC 1448

abstract:
  We present spectroscopic VLT/UVES observations of two emerging supernovae,
the Type Ia SN 2001el and the Type II SN 2003hn, in the spiral galaxy NGC 1448.
Our high resolution and high signal-to-noise spectra display atomic lines of Ca
II, Na I, Ti II and K I in the host galaxy. In the line of sight towards SN
2001el, we also detect over a dozen diffuse interstellar bands (DIBs) within
NGC 1448. These DIBs have strengths comparable to low reddening galactic lines
of sight, albeit with some variations. In particular, a good match is found
with the line of sight towards the sigma type diffuse cloud (HD 144217). The
DIBs towards SN 2003hn are significantly weaker, and this line of sight has
also lower sodium column density. The DIB central velocities show that the DIBs
towards SN 2001el are closely related to the strongest interstellar Ca II and
Na I components, indicating that the DIBs are preferentially produced in the
same cloud. The ratio of the 5797 and 5780 DIB strengths (r~0.14) suggests a
rather high UV field in the DIB environment towards SN 2001el. We also note
that the extinction estimates obtained from the sodium lines using multiple
line fitting agree with reddening estimates based on the colors of the Type Ia
SN 2001el.


title: The EMBH model in GRB 991216 and GRB 980425

abstract:
  This is a summary of the two talks presented at the Rome GRB meeting by C.L.
Bianco and R. Ruffini. It is shown that by respecting the Relative Space-Time
Transformation (RSTT) paradigm and the Interpretation of the Burst Structure
(IBS) paradigm, important inferences are possible: a) in the new physics
occurring in the energy sources of GRBs, b) on the structure of the bursts and
c) on the composition of the interstellar matter surrounding the source.


title:
Abundance stratification in Type Ia supernovae - I. The case of SN
  2002bo

abstract:
  The abundance stratification in the ejecta of the normal Type Ia supernova
2002bo is derived by fitting a series of spectra obtained at close time
intervals. A Monte Carlo code, modified to include abundance stratification, is
used to compute synthetic spectra at 13 epochs in the photospheric phase,
starting 13d before B maximum. A description of the abundance distribution
above 7600 km/s is thus obtained. Abundances in deeper layers, down to zero
velocity, are derived from models of two nebular-phase spectra. Elements
synthesized in different stages of burning are significantly, but not
completely, mixed in the ejecta. A total 56Ni mass of 0.52M_sun is derived.
Evidence for intermediate-mass elements at high velocities (> 18 000 km/s) is
found, most clearly in Si II 6355A, in Ca II H&K, and in the Ca II infrared
triplet. Carbon lines are not seen at any velocity, with possible implications
for the progenitor/explosion scenario. A synthetic bolometric light curve
computed using the inferred abundance distribution is in very good agreement
with the observed one, providing an independent check. In particular, the fast
rise of the light curve is reproduced very well. This is due to outward mixing
of 56Ni, which is clearly well determined by the spectroscopic modelling.


title: Distance of W3(OH) by VLBI annual parallax measurement

abstract:
  The most powerful tool for measuring distances within our Galaxy is the
annual parallax. We carried out phase-referencing VLBI observations of H$_{2}$O
masers in the star forming region W3(OH) with respect to the extragalactic
continuum source ICRF 0244+624 to measure their absolute proper motions. The
measured annual parallax is 0.484 $\pm$ 0.004 milli-arcseconds which
corresponds to a distance of 2.07^{+0.01}_{-0.02}$ kpc from the sun. This
distance is consistent with photometric and kinematic distances from previous
observations.


title: Close by Compact Objects and Recent Supernovae in the Solar Vicinity

abstract:
  I discuss young close-by compact objects, recent supernovae in the solar
neighbourhood, and point to their connection with cosmic ray studies.
Especially the role of the Gould Belt is underlined.


title:
Rotationally Supported Virgo Cluster Dwarf Elliptical Galaxies: Stripped
  Dwarf Irregular Galaxies?

abstract:
  New observations of 16 dwarf elliptical galaxies in the Virgo Cluster
indicate that at least seven dEs have significant velocity gradients along
their optical major axis, with typical rotation amplitudes of 20-30 km/s. Of
the remaining nine galaxies in this sample, 6 have velocity gradients less than
20 km/s kpc^{-1} while the other 3 observations had too low of a
signal--to--noise ratio to determine an accurate velocity gradient. Typical
velocity dispersions for these galaxies are ~44 +/- 5 km/s, indicating that
rotation can be a significant component of the stellar dynamics of Virgo dEs.
When corrected for the limited spatial extent of the spectral data, the
rotation amplitudes of the rotating dEs are comparable to those of similar
brightness dIs. Evidence for a relationship between the rotation amplitude and
galaxy luminosity is found, and, in fact, agrees well with the Tully-Fisher
relation. The similarity in the scaling relations of dIs and dEs implies that
it is unlikely that dEs evolve from significantly more luminous galaxies. These
observations reaffirm the possibility that some cluster dwarf elliptical
galaxies may be formed when the neutral gaseous medium is stripped from dwarf
irregular galaxies in the cluster environment. We hypothesize that several
different mechanisms are involved in the creation of the overall population of
dE galaxies, and that stripping of infalling dIs may be the dominant process in
the creation of dEs in clusters like Virgo.


title:
Stellar Populations of Dwarf Elliptical Galaxies: UBVRI Photometry of
  Dwarf Elliptical Galaxies in the Virgo Cluster

abstract:
  We present UBVRI surface photometry for 16 dwarf elliptical galaxies in the
Virgo Cluster with previously measured kinematic properties. The global optical
colors are red, with median values for the sample of 0.24 +/- 0.03 in (U-B),
0.77 +/- 0.02 in (B-V), and 1.02 +/- 0.03 in (V-I). We recover the well known
color-magnitude relation for cluster galaxies, but find no significant
difference in dominant stellar population between rotating and non-rotating
dwarf elliptical galaxies; the average age of the dominant stellar population
is 5-7 Gyr in all 16 galaxies in this sample. Analysis of optical spectra
confirm these age estimates and indicate Fe and Mg abundances in the range of
1/20th to 1/3 of solar, as expected for low luminosity galaxies. Based on Lick
indices and simple stellar population models, the derived [alpha/Fe] ratios are
sub-solar to solar, indicating a more gradual chemical enrichment history for
dEs as compared to giant elliptical galaxies in the Virgo Cluster. These
observations confirm the marked difference in stellar population and stellar
distribution between dwarf and giant elliptical galaxies and further
substantiate the need for alternative evolutionary scenarios for the lowest
mass cluster galaxies. We argue that it is likely that several different
physical mechanisms played a significant role in the production of the Virgo
cluster dE galaxies including in situ formation, infall of dEs that were once
part of Local Group analogs, and transformation of dwarf irregular galaxies by
the cluster environment. The observations support the hypothesis that a large
fraction of the Virgo cluster dEs are formed by ram pressure stripping of gas
from infalling dIs.


title: Spectroscopic Equilibrium of Iron in Metal-Rich Dwarfs

abstract:
  We analyze twenty five nearby metal-rich G and late-F dwarfs in order to
verify whether the spectroscopic equilibrium (LTE) of iron lines satisfy the
observational constraints imposed by the Infrared Flux Method (angular
diameters) and Hipparcos parallaxes. The atmospheric parameters derived from
iron lines (assuming LTE and employing 1D Kurucz model atmospheres) do not
satisfy simultaneously both observational constraints, probably because
classical modeling fails to reproduce the detailed line formation of FeI lines.


title: Compact objects for everyone: I. White dwarf stars

abstract:
  Based upon previous discussions on the structure of compact stars geared
towards undergraduate physics students, a real experiment involving two
upper-level undergraduate physics students, a beginning physics graduate, and
two advanced graduate students was conducted. A recent addition to the physics
curriculum at Florida State University, "The Physics of Stars", sparked quite a
few students' interests in the subject matter involving stellar structure.
This, coupled with "Stars and Statistical Physics" by Balian and Blaizot and
"Neutron Stars for Undergraduates" by Silbar and Reddy, is the cornerstone of
this small research group who tackled solving the structure equations for
compact objects in the Summer of 2004. Through the use of a simple
finite-difference algorithm coupled to Microsoft Excel and Maple, solutions to
the equations for stellar structure are presented in the Newtonian regime
appropriate to the physics of white dwarf stars.


title:
Detection and measurement in the V-band of the white dwarf spin period
  in the January 2004 outburst of DO (YY) Draconis

abstract:
  A modulation in the V-band with period 527.84+/-1.81 sec and amplitude 0.023
magnitude, attributable to the spin of the magnetic white dwarf primary star,
has been detected in 7.5 hours of V-band CCD photometry data recorded during
the January 2004 outburst of the DQ Her type dwarf nova DO (YY) Draconis. This
measurement is consistent with previous results for the white dwarf spin period
based on X-ray and UV observations made with the Hubble Space Telescope, ROSAT
and the Rossi X-ray Timing Explorer and appears to be the first independent
determination of the spin period in the V-band. It is consistent with previous
V-band observations in not showing a significant signal at the first harmonic
of the spin period as seen in X-ray and UV data. Light output in the V-band
peaks only once per rotation of the white dwarf rather than twice as seen in
X-rays and UV. Concurrent observation at optical and X-ray wavelengths is
needed to establish whether these two modulation behaviours occur at the same
time during the outburst and to investigate the phase relationship between
them. A coordinated observing campaign at a future outburst would help to
advance our understanding of this system.


title: Modelling the progenitors of Core-Collapse Supernovae

abstract:
  We present details of our investigation of the progenitors to core-collapse
supernovae. We discuss observations and the theory of the lowest-mass stars to
explode as supernovae.


title:
Correlated Infrared and X-ray Flux Changes Following the 2002 June
  Outburst of the Anomalous X-ray Pulsar 1E 2259+586

abstract:
  We present the results of a near-infrared monitoring program of the Anomalous
X-ray Pulsar 1E 2259+586, performed at the Gemini Observatory. This program
began three days after the pulsar's 2002 June outburst, and spans ~1.5 years.
We find that after an initial increase associated with the outburst, the
near-infrared flux decreased continually and reached the pre-burst quiescent
level after about one year. We compare both the near-infrared flux enhancement
and its decay to those of the X-ray afterglow, and find them to be remarkably
consistent. Fitting simple power laws to the RXTE pulsed flux and near-infrared
data for t>1 day post-burst, we find the following decay indices:
alpha=-0.21+/-0.01 (X-ray), alpha=-0.21+/-0.02 (near-infrared), where flux is a
function of time such that F is proportional to t^alpha. This suggests that the
enhanced infrared and X-ray fluxes have a physical link post-outburst, most
likely from the neutron-star magnetosphere.


title: Nebular and stellar properties of a metal poor HII galaxy at z=3.36

abstract:
  We have characterized the physical properties (electron temperature, density,
metallicity) of the ionized gas and the ionizing population (age, metallicity,
presence of WR stars) in the Lynx arc at z=3.36. This is a low metallicity
(~10% solar) HII galaxy which is undergoing a burst of star formation of <5 Myr
age. One possible scenario that explains the emission line spectrum of the Lynx
arc, the large strength of the nitrogen lines and the HeII emission is that the
object has experienced a merger event that has triggered a burst of star
formation. WR stars have formed that contribute to a fast enrichment of the ISM
and its overabundance of nitrogen.


title: Coarse-graining the distribution function of cold dark matter II

abstract:
  We study analytically the coarse and fine-grained distribution function
established by the self-similar infall of collisionless matter. We find this
function explicitly for isotropic and spherically symmetric systems in terms of
cosmological initial conditions. The coarse-grained function is structureless
and steady but the familiar phase space sheet sub-structure is recovered in the
fine-grained limit. By breaking the self-similarity of the halo infall we are
able to argue for a central density flattening. In addition there will be an
edge steepening. The best fitting analytic density function is likely to be
provided by a high order polytrope fit smoothly to an outer power law of index
-3 for isolated systems. There may be a transition to a -4 power law in the
outer regions of tidally truncated systems.
  We find a progressive central flattening that is expected to end either in
the non-singular isothermal sphere, or in non-singular metastable polytropic
cores. Therefore a collisionless system may pass through a family of polytropes
of increasing order, finally approaching the limit of the non-singular
isothermal sphere, if the `violent' collective relaxation is frequently
re-excited by `merger' events. Our results suggest that no physics beyond that
of the moderate collective relaxation often known as `violent relaxation' (due
we think to wave-particle scattering) is necessary to explain the nature of
dark matter density profiles.


title: Spacecraft Tracking with the SKA

abstract:
  The possibility of using the SKA for occasional support of scientific space
missions should be considered, along with all other science goals, in the
design of the array. The benefits of higher data rates from distant spacecraft
during high priority, short duration mission phases can be dramatic, while the
technical requirements on the SKA to allow this capability are very few. The
most fundamental requirement is coverage of the primary downlink frequencies
for deep space missions. Additional benefits can result from real-time high
precision angular position measurements of spacecraft. Such measurements allow
spacecraft navigation with reduced errors and reduced risk, but require at
least some long (thousands of km) baselines.


title: Simulations of Hot Bubbles in the ICM

abstract:
  We review the general properties of the intracluster medium (ICM) in clusters
that host a cooling flow, and in particular the effects on the ICM of the
injection of hot plasma by a powerful active galactic nucleus (AGN). It is
observed that, in some cases, the hot plasma produces cavities in the ICM that
finally detach and rise, perhaps buoyantly. The gas dynamics induced by the
rising bubbles can help explain the absence of a cooled gas component in
clusters with a cooling flow. This scenario is explored using numerical
simulations.


title: Polarization signatures of strong gravity in AGN accretion discs

abstract:
  The effects of strong gravity on the polarization of the Compton reflection
from an X-ray illuminated accretion disc are studied. The gravitational field
of a rotating black hole influences Stokes parameters of the radiation along
the propagation to a distant observer. Assuming the lamp-post model, the degree
and the angle of polarization are examined as functions of the observer's
inclination angle, of the height of the primary source and of the inner radius
of the disc emitting region. It is shown that polarimetry can provide essential
information on the properties of black holes sources, and it is argued that
time variation of the polarization angle is a strong signature of general
relativity effects. The expected polarization degree and angle should be
detectable by new generation polarimeters, like the one planned for the Xeus
mission.


title: DASI Three-Year Cosmic Microwave Background Polarization Results

abstract:
  We present the analysis of the complete 3-year data set obtained with the
Degree Angular Scale Interferometer (DASI) polarization experiment, operating
from the Amundsen-Scott South Pole research station. Additional data obtained
at the end of the 2002 Austral winter and throughout the 2003 season were added
to the data from which the first detection of polarization of the cosmic
microwave background radiation was reported. The analysis of the combined data
supports, with increased statistical power, all of the conclusions drawn from
the initial data set. In particular, the detection of E-mode polarization is
increased to 6.3 sigma confidence level, TE cross-polarization is detected at
2.9 sigma, and B-mode polarization is consistent with zero, with an upper limit
well below the level of the detected E-mode polarization. The results are in
excellent agreement with the predictions of the cosmological model that has
emerged from CMB temperature measurements. The analysis also demonstrates that
contamination of the data by known sources of foreground emission is
insignificant.


title: Anisotropic inverse Compton emission in the radio galaxy 3C 265

abstract:
  We present the results from a Chandra observation of the powerful radio
galaxy 3C 265. We detect X-ray emission from the nucleus, the radio hotspots
and lobes. In particular, the lobe X-ray emission is well explained as
anisotropic inverse Compton scattering of the nuclear photons by the
relativistic electrons in the radio lobes; the comparison between radio
synchrotron and IC emission yields a magnetic field strength a factor about 2
lower than that calculated under minimum energy conditions. The X-ray spectrum
of the nucleus is consistent with that of a powerful, strongly absorbed quasar
and the X-ray emission of the south-eastern hotspot can be successfully
reproduced by a combination of synchro-self Compton and inverse Compton
emission assuming a magnetic field slightly lower than equipartition.


title: AU Scale Structures in Extra-planar Gas

abstract:
  Recent spectroscopic observations of intermediate- and high-velocity clouds
(IVCs and HVCs) in the Milky Way halo have unveiled the presence of diffuse
interstellar molecular hydrogen (H_2) several kpc away from the Galactic disk.
Most of this H_2 gas appears to reside in relatively small (~0.1 pc), dense
(n_H~30 cm^-3) gaseous filaments that probably are part of the cold neutral
medium (CNM) in IVCs and HVCs. Also much smaller structures at AU scale and
very high densities (n_H~800 cm^-3) have been observed, suggesting the presence
of tiny-scale atomic structures (TSAS) in the Milky Way's extra-planar gas. It
is not yet understood how such objects can form and exist in the Milky Way
halo, but the high detection rate of H_2 absorption in IVCs implies that the
CNM represents a gas phase that is characteristic for neutral clouds in the
lower halo.


title: Towards a unified model for black hole X-ray binary jets

abstract:
  We present a unified semi-quantitative model for the disc-jet coupling in
black hole X-ray binary systems. We argue that during the rising phase of a
black hole transient outburst the steady jet known to be associated with the
canonical 'low/hard' state persists while the X-ray spectrum initially softens.
Subsequently, the jet becomes unstable and an optically thin radio outburst is
always associated with the soft X-ray peak at the end of this phase of
softening. This peak corresponds to a 'soft very high state' or 'steep power
law' state. Softer X-ray states are not associated with 'core' radio emission.
We further demonstrate quantitatively that the transient jets associated with
these optically thin events are considerably more relativistic than those in
the 'low/hard' X-ray state. This in turn implies that as the disc makes its
collapse inwards the jet Lorentz factor rapidly increases, resulting in an
internal shock in the outflow, which is the cause of the observed optically
thin radio emission. In addition, we estimate the jet power for a number of
such transient events as a function of X-ray luminosity, and find them to be
comparable to an extrapolation of the functions estimated for the 'low/hard'
state jets. Finally, we attempt to fit these results together into a coherent
semi-quantitative model for the disc-jet coupling in all black hole X-ray
binary systems (abridged).


title: High Energy Gamma Rays

abstract:
  The Very High Energy Gamma Ray Astronomy (VHE) is a rapidly evolving branch
of modern astronomy, which covers the range from about 50 GeV to several tens
of TeV from the ground. In the past years, the second generation instruments
firmly established a growing and varied list of sources including plerions,
supernova remnants and active galactic nuclei, and started to study some
fundamental questions such as the origin of cosmic rays or the emission
mechanisms of the active galactic nuclei.
  New results now include the first VHE unidentified sources as well as more
puzzling sources such as the Galactic center. The arrival of new generation
instruments (HESS, CANGAROO III, VERITAS, MAGIC) already gives a impressive
look at the near future. Here we attempt to summarize the current status of the
field. We briefly describe the instruments and analysis techniques, and give an
outlook on the sources detected sofar.


title: The distance to the Pleiades: Main sequence fitting in the near infrared

abstract:
  Hipparcos parallax measurements of stars in the Pleiades notoriously result
in a cluster distance of 118 pc; ~10% shorter than the `classical' results of
MS-fitting. In an earlier paper we developed a purely empirical MS-fitting
method to address this problem, which produced conflicting results between the
(B-V) and (V-I) colour indices, indicating that the cluster's photometric
metallicity is substantially lower than its (~solar) spectroscopic metallicity.
We were able to reconcile the discrepancy by assuming [Fe/H]=-0.4 (as indicated
from (B-V)/(V-I) colour-colour plots), and the distance moduli obtained from
the 2 indices were in agreement with the Hipparcos result, within the 1sig
errors. With the release of the 2MASS All Sky Catalogue, we now apply our
MS-fitting method to the Pleiades using the infrared colours, in order to test
the plausibility of our earlier result. Fitting in the V/(V-K) and K/(J-K)
colour planes, we find that assuming a subsolar metallicity does not produce
distances in agreement with the (B-V) and (V-I) results. However the infrared
plus (V-I) distances are in mutual agreement when adopting the spectroscopic
metallicity. By considering only stars with Mv<=6, the infrared and optical
colour indices all yield consistent distances using the spectroscopic [Fe/H].
The concordant distances thus obtained from the (B-V), (V-I), (V-K) and (J-K)
indices yield a mean of 133.8+/-3 pc, in excellent agreement with the
pre-Hipparcos MS-fitting results, and the most recent determinations from other
methods. We conclude that there are two distinct issues affecting the Pleiades:
the Hipparcos parallax is in error by ~10%, as previously claimed; the (B-V)
colours of the lower MS are anomalous, and we caution against their use for
MS-fitting to the Pleiades and similarly young open clusters. (Abridged)


title: On the structure of line-driven winds near black holes

abstract:
  A general physical mechanism of the formation of line-driven winds at the
vicinity of strong gravitational field sources is investigated in the frame of
General Relativity. We argue that gravitational redshifting should be taken
into account to model such outflows. The generalization of the Sobolev
approximation in the frame of General Relativity is presented. We consider all
processes in the metric of a nonrotating (Schwarzschild) black hole. The
radiation force that is due to absorbtion of the radiation flux in lines is
derived. It is demonstrated that if gravitational redshifting is taken into
account, the radiation force becomes a function of the local velocity gradient
(as in the standard line-driven wind theory) and the gradient of $g_{00}$. We
derive a general relativistic equation of motion describing such flow. A
solution of the equation of motion is obtained and confronted with that
obtained from the Castor, Abbott & Klein (CAK) theory. It is shown that the
proposed mechanism could have an important contribution to the formation of
line-driven outflows from compact objects.


title: Relic gravitational waves and present accelerated expansion

abstract:
  We calculate the current power spectrum of the gravitational waves created at
the big bang (and later amplified by the different transitions during the
Universe expansion) taking into account the present stage of accelerated
expansion. Likewise, we determine the power spectrum in a hypothetical second
dust era that would follow the present one if at some future time the dark
energy, that supposedly drives the current accelerated expansion, evolved in
such a way that it became dynamically equivalent to cold dark matter. The
calculated power spectrum as well as the evolution of the density parameter of
the waves may serve to discriminate between phases of expansion and may help
ascertain the nature of dark energy.


title: Stationary fluid models for the extra-planar gas in spiral galaxies

abstract:
  We show how to construct families of stationary hydrodynamical configurations
that reproduce the observed vertical gradient of the rotation velocity of the
extra-planar gas in spiral galaxies. We then present a simple model for the
lagging halo of the spiral galaxy NGC 891, which is in agreement with the HI
observations. Our method is based on well known properties of baroclinic
solutions, and it is an elementary application of a much more general and
flexible method.


title: A physically motivated toy model for the BH-spheroid coevolution

abstract:
  We present a summary of the results obtained with a time-dependent, one-zone
toy model aimed at exploring the importance of radiative feedback on the
co-evolution of massive black holes (MBHs) at the center of stellar spheroids
and their stellar and gaseous components. We consider cosmological infall of
gas as well as the mass and energy return for the evolving stellar population.
The AGN radiative heating and cooling are described by assuming photoionization
equilibrium of a plasma interacting with the average quasar SED. Our results
nicely support a new scenario in which the AGN accretion phase characterized by
a very short duty-cycle (and now common in the Universe) is due to radiative
feedback. The establishment of this phase is recorded as a fossil in the
Magorrian and Mbh-sigma relations.


title: Infrasound generation by turbulent convection

abstract:
  Low frequency acoustic wave generation is studied taking into account the
effect of stratification, inhomogeneity of background velocity profile and
temperature fluctuations. It is shown that for the typical parameters of
convective storms the dipole radiation related to temperature inhomogeneities
is at least of the same order as radiation of Lighthill's quadrupole source. It
is also shown that the source related to stratification could have valuable
contribution whereas some other sources are shown to be inefficient.


title:
Observations of magnetic fields in the Milky Way and in nearby galaxies
  with a Square Kilometre Array

abstract:
  The role of magnetic fields in the dynamical evolution of galaxies and of the
interstellar medium (ISM) is not well understood, mainly because such fields
are difficult to directly observe. Radio astronomy provides the best tools to
measure magnetic fields: synchrotron radiation traces fields illuminated by
cosmic-ray electrons, while Faraday rotation and Zeeman splitting allow us to
detect fields in all kinds of astronomical plasmas, from lowest to highest
densities. Here we describe how fundamental new advances in studying magnetic
fields, both in our own Milky Way and in other nearby galaxies, can be made
through observations with the proposed Square Kilometre Array. Underpinning
much of what we propose is an all-sky survey of Faraday rotation, in which we
will accumulate tens of millions of rotation measure measurements toward
background radio sources. This will provide a unique database for studying
magnetic fields in individual Galactic supernova remnants and HII regions, for
characterizing the overall magnetic geometry of our Galaxy's disk and halo, and
for understanding the structure and evolution of magnetic fields in galaxies.
Also of considerable interest will be the mapping of diffuse polarized emission
from the Milky Way in many narrow bands over a wide frequency range. This will
allow us to carry out Faraday tomography of the Galaxy, yielding a
high-resolution three-dimensional picture of the magnetic field within a few
kpc of the Sun, and allowing us to understand its coupling to the other
components of the ISM. Finally, direct synchrotron imaging of a large number of
nearby galaxies, combined with Faraday rotation data, will allow us to
determine the magnetic field structure in these sources, and to test both the
dynamo and primordial field theories for field origin and amplification.


title: Predicting Substructure in CDM Haloes

abstract:
  Observations of multiple-image gravitational lens systems suggest that the
projected mass distributions of galaxy haloes may contain substantial
inhomogeneities. The fraction of the halo mass in dense substructure is still
highly uncertain, but could be as large as a few percent. While halo
substructure is seen in numerical simulations of CDM haloes, little of this
substructure survives in the innermost regions of haloes, and thus the
observational claims for substructure at small projected radii are slightly
surprising. There is evidence, however, that even the highest-resolution
simulations published to-date are still limited by numerical effects that heat
and disrupt substructure artificially in high-density regions. By comparing
numerical and semi-analytic models of halo substructure, we show that current
simulations probably underestimate the mass fraction in substructure at small
projected radii, by a factor of at least 2-3. We discuss the prospects for
using lensing observations as a fundamental test of the nature of dark matter.


title: Completing HI observations of galaxies in the Virgo cluster

abstract:
  High sensitivity (rms noise $\sim 0.5$ mJy) 21-cm HI line observations were
made of 33 galaxies in the Virgo cluster, using the refurbished Arecibo
telescope, which resulted in the detection of 12 objects. These data, combined
with the measurements available from the literature, provide the first set of
HI data that is complete for all 355 late-type (Sa-Im-BCD) galaxies in the
Virgo cluster with $m_p \leq 18.0$ mag. The Virgo cluster HI mass function
(HIMF) that was derived for this optically selected galaxy sample is in
agreement with the HIMF derived for the Virgo cluster from the blind HIJASS HI
survey and is inconsistent with the Field HIMF. This indicates that both in
this rich cluster and in the general field, neutral hydrogen is primarily
associated with late-type galaxies, with marginal contributions from early-type
galaxies and isolated HI clouds. The inconsistency between the cluster and the
field HIMF derives primarily from the difference in the optical luminosity
function of late-type galaxies in the two environments, combined with the HI
deficiency that is known to occur in galaxies in rich clusters.


title: Compact high-velocity clouds around the Galaxy and M31

abstract:
  We have observed 11 compact high-velocity clouds in the 21-cm line of neutral
hydrogen with the 100-m telescope in Effelsberg. Our observations show that
most of the clouds have a rather complex morphology. Head-tail structures and
bow-shock shapes suggest that many of the CHVCs are interacting with an ambient
medium, providing additional evidence for a circumgalactic CHVC population. In
order to verify the concept of a circumgalactic population directly, we have
started an HI blind survey to search for CHVCs in the neighbourhood of M31,
using the Effelsberg telescope. We can confirm some of the extended HI
structures discovered by Thilker et al. (2004) with the Green Bank Telescope
(GBT), whereas we have not yet found any cloud similar to the CHVCs observed
near the Milky Way. Our non-detection suggests an upper limit for the distance
of CHVCs from their host galaxies of about 60 kpc.


title:
Abundances and kinematics of a candidate sub-damped Lyman-alpha galaxy
  toward PHL 1226

abstract:
  The spectrum of the quasar PHL 1226 is known to have a strong Mg II and
sub-damped Lyman-alpha (sub-DLA) absorption line system with
N(HI)=(5+/-2)*10^19 cm^-2 at z=0.1602. Using integral field spectra from the
Potsdam Multi Aperture Spectrophotometer (PMAS) we investigate a galaxy at an
impact parameter of 6".4 which is most probably responsible for the absorption
lines. A fainter galaxy at a similar redshift and a slightly larger distance
from the QSO is known to exist, but we assume that the absorption is caused by
the more nearby galaxy. From optical Balmer lines we estimate an intrinsic
reddening consistent with 0, and a moderate star formation rate of 0.5 M_sun
yr^-1, is inferred from the Halpha luminosity. Using nebular emission line
ratios we find a solar oxygen abundance 12+log(O/H)=8.7+/-0.1 and a solar
nitrogen to oxygen abundance ratio log(N/O)=-1.0+/-0.2. This abundance is
larger than those of all known sub-DLA systems derived from analyses of metal
absorption lines in quasar spectra. On the other hand, the properties are
compatible with the most metal rich galaxies responsible for strong Mg II
absorption systems. These two categories can be reconciled if we assume an
abundance gradient similar to local galaxies. Under that assumption we predict
abundances 12+log(O/H)=7.1 and log(N/O)=-1.9 for the sub-DLA cloud, which is
similar to high redshift DLA and sub-DLA systems. We find evidence for a
rotational velocity of ~200 km s^-1 over a length of ~7 kpc. From the geometry
and kinematics of the galaxy we estimate that the absorbing cloud does not
belong to a rotating disk, but could originate in a rotating halo.


title: Testing for the Pioneer anomaly on a Pluto exploration mission

abstract:
  The Doppler-tracking data of the Pioneer 10 and 11 spacecraft show an
unmodelled constant acceleration in the direction of the inner Solar System. An
overview of the phenomenon, commonly dubbed the Pioneer anomaly, is given and
the possibility for an experimental test of the anomaly as a secondary goal of
an upcoming space mission is discussed using a putative Pluto orbiter probe as
a paradigm.


title: The Effects of Multiple Weak Deflections in Galaxy-Galaxy Lensing

abstract:
  The Hubble Deep Field (North) and the flanking fields are used investigate
the occurrence of multiple weak lensing deflections along the line of sight in
relatively deep imaging data (z_lens ~ 0.6, z_source ~ 1.2). Ray tracing
simulations of galaxy-galaxy lensing in the HDF-North show that proper
inclusion of multiple weak deflections is important for a correct prediction of
the net shear for most sources, and for a given source redshift the number of
multiple weak deflections is largely insensitive to the cosmography. The
effects of multiple weak deflections on the magnitude of the weak lensing
signal are, of course, strong functions of the adopted halo parameters.
Independent of the halo parameters, however, the closest lens to a source (in
projection on the sky) is not the strongest lens in the case of more than 50%
of the sources which acquire a net shear of \gamma < 0.01. In addition,
multiple weak deflections result in a tangential shear about the lens centers
that is greater than the tangential shear that would occur if source galaxies
were lensed solely by the closest lens. Further, multiple weak deflections give
rise to correlated image ellipticities and account for a substantial amount of
the total cosmic shear signal on small angular scales in Lambda-CDM and open
CDM models.


title: Intermediate-band Photometry of Type Ia Supernovae

abstract:
  We present optical light curves of five Type Ia supernovae (2002er, 2002fk,
2003cg, 2003du, 2003fk). The photometric observations were performed in a set
of intermediate-band filters. SNe 2002er, 2003du appear to be normal SN Ia
events with similar light curve shapes, while SN 2003kf shows the behavior of a
brighter SN Ia with slower decline rate after maximum. The light curves of SN
2003cg is unusual; they show a fast rise and dramatic decline near maximum and
do not display secondary peak at longer wavelengths during 15-30 days after
maximum light. This suggests that SN 2003cg is likely to be an intrinsically
subluminous, 91bg-like SN Ia. Exploration of SN Ia feature lines through
intermediate-band photometry is briefly discussed.


title:
Variabilities of Gamma-Ray Burst Afterglows: Long-acting Engine,
  Anisotropic Jet or Many Fluctuating Regions?

abstract:
  We show that simple kinematic arguments can give limits on the timescale and
amplitude of variabilities in gamma-ray burst (GRB) afterglows, especially when
the variability timescale is shorter than the observed time since the burst
\Delta t < t. These limits help us to identify the sources of afterglow
variability. The afterglows of GRB 011211 and GRB 021004 marginally violate
these limits. If such violation is confirmed by the Swift satellite, a possible
explanation is that (1) the compact objects that power GRB jets continue to
eject an intermittent outflow for a very long timescale (> 1 day), (2) the GRB
jet from the central engine has a temporal anisotropy with a large brightness
contrast > 10 and small angular structure < 10^{-2}, or (3) many (> 10^{3})
regions fluctuate simultaneously in the emitting site.


title:
The Search for Anisotropy in the Arrival Directions of Ultra-High Energy
  Cosmic Rays Observed by the High Resolution Fly's Eye Detector in Monocular
  Mode

abstract:
  The High Resolution Fly's Eye HiRes-I detector has now been in operation in
monocular mode for over six years. During that time span, HiRes-I has
accumulated a larger exposure to Ultra-High Energy Cosmic Rays (UHECRs) above
10^19 eV than any other experiment built to date. This presents an
unprecedented opportunity to search for anisotropy in the arrival directions of
UHECRs. We present results of a search for dipole distributions oriented
towards major astrophysical landmarks and a search for small-scale clustering.
We conclude that the HiRes-I data set is, in fact, consistent with an isotropic
source model.


title:
Black Holes From the Dark Ages: Exploring the Reionization Era and Early
  Structure Formation With Quasars and Gamma-Ray Bursts

abstract:
  The cosmic reionization era, which includes formation of the first stars,
galaxies, and AGN, is now one of the most active frontiers of cosmological
research. We review briefly our current understanding of the early structure
formation, and use the ideas about a joint formation of massive black holes
(which power the early QSOs) and their host galaxies to employ high-redshift
QSOs as probes of the early galaxy formation and primordial large-scale
structure. There is a growing evidence for a strong biasing in the formation of
the first luminous sources, which would lead to a clumpy reionization.
Absorption spectroscopy of QSOs at z > 6 indicates the end of the reionization
era at z ~ 6; yet measurements from the WMAP satellite suggest and early
reionization at z ~ 10 - 20. The first generation of massive stars, perhaps
aided by the early mini-quasars, may have reionized the universe at such high
redshifts, but their feedback may have disrupted the subsequent star and galaxy
formation, leading to an extended and perhaps multimodal reionization history
ending by z ~ 6. Observations of gamma-ray bursts from the death events of
these putative Population III stars may provide essential insight into the
primordial structure formation, reionization, early chemical enrichment, and
formation of seed black holes which may grow to become central engines of
luminous quasars.


title: Strong-Field Tests of Gravity Using Pulsars and Black Holes

abstract:
  The sensitivity of the SKA enables a number of tests of theories of gravity.
A Galactic Census of pulsars will discover most of the active pulsars in the
Galaxy beamed toward us. In this census will almost certainly be pulsar-black
hole binaries as well as pulsars orbiting the super-massive black hole in the
Galactic centre. These systems are unique in their capability to probe the
ultra-strong field limit of relativistic gravity. These measurements can be
used to test the Cosmic Censorship Conjecture and the No-Hair theorem.
  The large number of millisecond pulsars discovered with the SKA will also
provide a dense array of precision clocks on the sky. These clocks will act as
the multiple arms of a huge gravitational wave detector, which can be used to
detect and measure the stochastic cosmological gravitational wave background
that is expected from a number of sources.


title:
First measurements of the polarization of the cosmic microwave
  background radiation at small angular scales from CAPMAP

abstract:
  Polarization results from the Cosmic Anisotropy Polarization MAPper (CAPMAP)
experiment are reported. These are based upon 433 hours, after cuts, observing
a 2 square degree patch around the North Celestial Pole (NCP) with four 90 GHz
correlation polarimeters coupled to optics defining $4\arcmin$ beams. The
E-mode flat bandpower anisotropy within $\ell=940^{+330}_{-300}$ is measured as
66$^{+69}_{-29} \mu$K$^2$; the 95% Confidence level upper limit for B-mode
power within $\ell=1050^{+590}_{-520}$ is measured as 38 $\mu$K$^2$.