title:
The Chandra Detection of Galactic Center X-ray Features G359.89-0.08 and
  G359.54+0.18

abstract:
  We report on the detection of two elongated X-ray features G359.89-0.08 and
G359.54+0.18 in the Galactic center (GC) region using the Chandra X-ray
Observatory. G359.89-0.08 is an elongated X-ray feature located $\sim$2\arcmin
in projection south of the center of the Galaxy, SgrA$^*$. This X-ray feature
source is partially coincident with a slightly curved (``wisp''-like)
non-thermal radio source. The X-ray spectrum of G359.89-0.08 can be best
characterized as non-thermal, with a photon index of 2. The morphological and
spectral characteristics of the X-ray and radio emission associated with
G359.89-0.08 are best interpreted as the synchrotron emission from a
ram-pressure confined pulsar wind nebula. G359.54+0.18 is one of the most
prominent radio non-thermal filaments (NTFs) in the GC region, located
$\sim$30\arcmin in projection from SgrA$^*$. A narrow ($\sim$10\arcsec)
filament of X-ray emission appears to arise from one of the two strands that
comprise the radio NTF. Although the photon statistics are poor for this
source, the X-ray emission is also likely to be non-thermal in nature. Several
models for the production of X-ray emission in G359.54+0.18 are discussed.


title:
Measurements of Proton, Helium and Muon Spectra at Small Atmospheric
  Depths with the BESS Spectrometer

abstract:
  The cosmic-ray proton, helium, and muon spectra at small atmospheric depths
of 4.5 -- 28 g/cm^2 were precisely measured during the slow descending period
of the BESS-2001 balloon flight. The variation of atmospheric secondary
particle fluxes as a function of atmospheric depth provides fundamental
information to study hadronic interactions of the primary cosmic rays with the
atmosphere.


title: Abundant H2D+ in the pre-stellar core L1544

abstract:
  We have detected the 372 GHz line of ortho-H2D+ towards the pre-stellar core
L1544. The strongest emission (T_mb ~ 1 K) occurs at the peak of the millimeter
continuum emission, while measurements at offset positions indicate that H2D+
is confined within ~ 20 arcsec, where CO is highly depleted. The derived H2D+
abundance of ~ 10^{-9} is comparable with previous estimates of the electron
abundance in the core, which suggests that H2D+ is the main molecular ion in
the central 20 arcsec (2800 AU) of L1544. This confirms the expectations that
H2D+ is dramatically enhanced in gas depleted of molecules other than H2. The
measured abundance even exceeds the present model predictions by about a factor
ten. One possibility is that all CNO-bearing neutral species, including atomic
oxygen, are almost completely (> 98%) frozen within a radius of ~2800 AU.


title: Nanoengineered Astronomical Optics

abstract:
  We describe a technology for the fabrication of inexpensive and versatile
mirrors through the use of a new type of nanoengineered optical material
composed by the spreading of a self-assembling reflective colloidal film spread
at the surface of a liquid. These new reflecting liquids offer interesting
possibilities for astronomical instrumentation. For example, they can replace
mercury in conventional rotating liquid mirrors. The main advantages offered
include extremely low cost and, by coating a viscous liquid, the possibility of
tilting the mirror by a few tens of degrees. We also have coated ferromagnetic
liquids with these reflecting films. The resulting surfaces can be shaped by
the application of a magnetic field, yielding reflecting surfaces that can have
complicated shapes that can rapidly shift with time. These inexpensive and
versatile optical elements could have numerous scientific and technological
applications. Among possible astronomical applications, they could be used to
make large inexpensive adaptive mirrors exhibiting strokes ranging from
nanometers to several millimeters.


title:
High Spatial Resolution Mid-infrared Observations of Three Seyfert
  Galaxies

abstract:
  Images at 12.5 microns of nuclei of three nearby Seyfert galaxies -- NGC
1275, NGC 4151 and NGC 7469 -- have been obtained with the Keck 10-m Telescope.
NGC 7469 is resolved and deconvolution delineates a structure <0.04"x0.08" or
<13x26 pc at a position angle of 135deg. From a comparison with structure seen
at millimeter wavelengths, this structure is interpreted as a disk aligned with
the molecular gas in the central few hundred parsecs of the galaxy. NGC 1275
and NGC 4151 are not resolved; limits on the sizes of these nuclei are 0.08"
and 0.16", corresponding to physical spatial scales of 28 and 10 pc. The lower
limits to the brightness temperatures implied by these size limits and the
measured flux densities are within ~50K of the 12 micron to 25 micron color
temperatures of these systems as inferred from IRAS observations. The angular
size limits are within a factor of 2.5 of the sizes required to spatially
resolve thermal emission from dust heated by a central luminosity source. These
sizes preclude significant contributions to the nuclear infrared emission from
star forming regions.


title: The Supernova associated with GRB 030329

abstract:
  The relative proximity of the recent gamma ray burst (GRB) 030329 resulted in
a large gamma-ray fluence and in the brightest-ever afterglow (AG), hours after
the burst, in the radio, optical and X-ray bands, permitting precise AG
measurements, sensitive tests of models and an excellent occasion to
investigate the association of GRBs with supernovae (SNe). The Cannonball (CB)
model provides a good, simple and universal description of all AGs of GRBs of
known redshift, so that it is straightforward to use it to predict what the
expected SN signatures are. In the case of GRB 030329, 10 days after burst the
AG should begin to reveal the lightcurve, spectrum and polarization of an
underlying SN --akin to SN1998bw-- which will peak in the NIR/optical band
around day 15. These effects will be easily observable if indeed SN1998bw is a
good ``standard candle'' for GRB-associated SNe and if the so far unknown
extinction in the host galaxy is not too large.


title:
Interpretation of the Stephan Quintet Galaxy Cluster using
  Hydro-Gravitational Theory

abstract:
  Stephan's Quintet (SQ) is a compact group of galaxies that has been well
studied since its discovery in 1877 but is mysterious using cold dark matter
hierarchical clustering cosmology (CDMHCC). Anomalous red shifts z =
(0.0027,0.019, 0.022, 0.022, 0.022) among galaxies in SQ either; reduce it to a
Trio with two highly improbable intruders from CDMHCC, or support the Arp
(1973) hypothesis that its red shifts may be intrinsic. An alternative is
provided by the Gibson 1996-2000 hydro-gravitational-theory (HGT) where
superclusters, clusters and galaxies all originate by universe expansion and
gravitational fragmentation in the super-viscous plasma epoch (after which the
gas condenses as 10^{24} kg fog-particles in metastable 10^{36} kg
dark-matter-clumps). By this fluid mechanical cosmology, the SQ galaxies gently
separated recently and remain precisely along a line of sight because of
perspective and the small transverse velocities permitted by their sticky,
viscous-gravitational, beginnings. Star and gas bridges and
young-globular-star-cluster (YGC) trails observed by the HST are triggered as
SQ galaxies separate through each other's frozen baryonic-dark-matter halos of
dark proto-globular-cluster (PGC) clumps of planetary-mass
primordial-fog-particles (PFPs). Discordant red shifts (from CDMHCC) between
angularly clustered quasars and bright galaxies are similarly explained by HGT.


title: Cosmology with Supernovae

abstract:
  This review gives an update of the cosmological use of SNe Ia and the
progress made in testing their properties from the local universe to high-z.
The cosmological road from high-z supernovae down to Galactic SNe Ia is
followed in search of the answer to standing questions on their nature and
their validity as cosmological indicators.


title: Search for the companions of Galactic SNe Ia

abstract:
  The central regions of the remnants of Galactic SNe Ia have been examined for
the presence of companion stars of the exploded supernovae. We present the
results of this survey for the historical SN 1572 and SN 1006. The spectra of
the stars are modeled to obtain Teff, log g and the metallicity. Radial
velocities are obtained with an accuracy of 5--10 km s$^{-1}$. Implications for
the nature of the companion star in SNeIa follow.


title: Optical Flashes and Very Early Afterglows in Wind Environments

abstract:
  The interaction of a relativistic fireball with its ambient medium is
described through two shocks: a reverse shock that propagates into the
fireball, and a forward shock that propagates into the medium. The observed
optical flash of GRB 990123 has been considered to be the emission from such a
reverse shock. The observational properties of afterglows suggest that the
progenitors of some GRBs may be massive stars and their surrounding media may
be stellar winds. We here study very early afterglows from the reverse and
forward shocks in winds. An optical flash mainly arises from the relativistic
reverse shock while a radio flare is produced by the forward shock. The peak
flux densities of optical flashes are larger than 1 Jy for typical parameters,
if we do not take into account some appropriate dust obscuration along the line
of sight. The radio flare always has a long lasting constant flux, which will
not be covered up by interstellar scintillation. The non-detections of optical
flashes brighter than about 9th magnitude may constrain the GRBs isotropic
energies to be no more than a few $10^{52}$ ergs and wind intensities to be
relatively weak.


title:
NGC 1883: a neglected intermediate-age open cluster located in the
  outskirts of the Galactic disk

abstract:
  We report on $BVI$ CCD photometry of a field centered in the region of the
open cluster NGC 1883 down to V=21. This cluster has never been studied
insofar, and we provide for the first time estimates of its fundamental
parameters, namely radial extent, age, distance and reddening. We find that the
cluster has a radius of about 2.5 arcmin, and shows signatures of dynamical
relaxation. NGC 1883 is located in the anti-center direction, and exhibits a
reddening in the range E$(B-V)= 0.23-0.35$, depending on the metal abundance.
It turns out to be of intermediate-age (1 billion years old), and quite distant
for an open cluster. In fact it is located 4.8 kpc from the Sun, and more than
13 kpc from the Galactic center. This results makes NGC 1883 one of the most
peripheral old open clusters, with important consequences for the trend of the
metallicity with distance in the outer Galactic disk.


title: Optical Light Curves of Supernovae

abstract:
  Photometry is the most easily acquired information about supernovae. The
light curves constructed from regular imaging provide signatures not only for
the energy input, the radiation escape, the local environment and the
progenitor stars, but also for the intervening dust. They are the main tool for
the use of supernovae as distance indicators through the determination of the
luminosity. The light curve of SN 1987A still is the richest and longest
observed example for a core-collapse supernova. Despite the peculiar nature of
this object, as explosion of a blue supergiant, it displayed all the
characteristics of Type II supernovae. The light curves of Type Ib/c supernovae
are more homogeneous, but still display the signatures of explosions in massive
stars, among them early interaction with their circumstellar material. Wrinkles
in the near-uniform appearance of thermonuclear (Type Ia) supernovae have
emerged during the past decade. Subtle differences have been observed
especially at near-infrared wavelengths. Interestingly, the light curve shapes
appear to correlate with a variety of other characteristics of these
supernovae. The construction of bolometric light curves provides the most
direct link to theoretical predictions and can yield sorely needed constraints
for the models. First steps in this direction have been already made.


title:
Running of the Scalar Spectral Index and Observational Signatures of
  Inflation

abstract:
  Some of the consequences for inflationary cosmology of a scale dependence
(running) in the tilt of the scalar perturbation spectrum are considered. In
the limit where the running is itself approximately scale-invariant, a
relationship is found between the scalar and tensor perturbation amplitudes,
the scalar spectral index and its running. This relationship is independent of
the functional form of the inflaton potential. More general settings, including
that of braneworld cosmological models, are also considered. It is found that
for the Randall-Sundrum single braneworld scenario, the corresponding relation
between the observables takes precisely the same form as that arising in the
standard cosmology. Some implications of the observations failing to satisfy
such a relationship are discussed.


title: Evidence for Jet Collimation in SS 433 with the Chandra HETGS

abstract:
  High-resolution X-ray spectra of SS 433 obtained after a binary egress with
the Chandra High Energy Transmission Grating Spectrometer (HETGS) were studied.
Many Doppler-shifted X-ray emission lines from highly ionized elements were
detected. The initial temperature of the jets is estimated to be 20 keV. The
lines are found to generally be broader than the instrumented resolution. The
widths of the Fe XXV K-alpha and Si XIII K-alpha lines correspond to velocity
dispersions of 2100 (+600/-340) km/s and 840 (+180/-150) km/s respectively, in
terms of Gaussian sigma. Neither the measured line widths nor their dependence
on the atomic number can be explained by thermal broadening alone. Alternative
explanations of the observed line widths are discussed, including in particular
a progressive jet collimation along its axis.


title:
Semi-classical theory of collisional depolarization of spectral lines by
  atomic hydrogen. I: application to p states of neutral atoms

abstract:
  The present paper extends the method of Anstee, Barklem and O'Mara (Anstee
1992; Anstee & O'Mara 1991, 1995; Anstee, O'Mara & Ross 1997; Barklem 1998;
Barklem & O'Mara 1997; Barklem, O'Mara & Ross 1998), developed during the
1990's for collisional line broadening by atomic hydrogen, to the
depolarization of spectral lines of neutral atoms by collisions with atomic
hydrogen. In the present paper, we will limit the calculations to p (l=1)
atomic levels. The depolarization cross sections and depolarization rates are
computed. In Table 2 cross sections as functions of the relative velocity and
effective quantum number are given, allowing for the computation for any p
atomic level. Our results are compared to quantum chemistry calculations where
possible. The sensitivity of depolarization cross sections to regions of the
potential is examined. We conclude that the accuracy obtained with our method
(< 20 % for the depolarization rates) is promising for its extension to higher
l-values for the interpretation of the ``second solar spectrum''. This will be
the object of further papers.


title: Adaptive optics imaging survey of the Tucana-Horologium association

abstract:
  We present the results of an adaptive optics (AO) imaging survey of the
common associations of Tucana and Horologium, carried out at the ESO 3.6m
telescope with the ADONIS/SHARPII system. Based on our observations of two
dozen probable association members, HIP 1910 and HIP 108422 appear to have
low-mass stellar companions, while HIP 6856 and GSC 8047-0232 have possible
sub-stellar candidate companions. Astrometric measurements, performed in
November 2000 and October 2001, indicate that HIP 1910 B likely is bound to its
primary, but are inconclusive in the case of the candidate companion to HIP
6856. Additional observations are needed to confirm the HIP 6856 companionship
as well as for HIP 108422 and GSC 8047-0232.


title: A search for planets in the metal-enriched binary HD 219542

abstract:
  The components of the wide binary HD 219542 were recently found to differ in
metallicity by about 0.1 dex (Gratton et al. A&A 377, 123). In this paper, we
present the results of 2 years of high precision radial velocity monitoring of
these stars performed at the Telecopio Nazionale Galileo (TNG) using the high
resolution spectrograph SARG. No indication for radial velocity variations
above the measurement errors (5 m/s) was found for the metal richer component
A. This allows us to place upper mass-limits for planets around this star. HD
219542B instead shows a low amplitude variation with a 112 day period at a
confidence level of about 96-97%. This might suggest the presence of a
Saturn-mass planet, although it is still possible that these variations are due
to moderate activity of the star. Tests based on variations of bisectors,
stellar magnitude and line equivalent widths were inconclusive so far.


title:
A First Close Look at the Balmer Edge Behavior of the Quasar Big Blue
  Bump

abstract:
  We have found for the first time a Balmer edge feature in the polarized flux
spectrum of a quasar (Ton 202). The edge feature is seen as a discontinuity in
the slope, rather than as a discontinuity in the absolute flux. Since the
polarized flux contains essentially no broad emission lines, it is considered
to arise interior to the broad emission line region, showing the spectrum with
all the emissions outside the nucleus scraped off and removed. Therefore, the
polarized flux spectrum is likely to reveal features intrinsic to the Big Blue
Bump emission. In this case, the existence of the Balmer edge feature, seen in
absorption in the shorter wavelength side, indicates that the Big Blue Bump is
indeed thermal and optically thick.


title:
Clues to the nature of damped Lyman alpha systems from chemical
  evolution models

abstract:
  The evolution of the metallicity of damped Lyman alpha systems (DLAs) is
investigated in order to understand the nature of these systems. The
observational data on chemical abundances of DLAs are analysed with robust
statistical methods, and the abundances are corrected for dust depletion. The
results of this analysis are compared to predictions of several classes of
chemical evolution models: one-zone dwarf galaxy models, multizone disk models,
and chemodynamical models representing dwarf galaxies. We compare the
observational data on the [alpha/Fe] and [N/alpha] ratios to the predictions
from the models. In DLAs, these ratios are only partially reproduced by the
dwarf galaxy one-zone model and by the disk model. On the other hand, the
chemodynamical model for dwarf galaxies reproduces the properties of nearly all
DLAs. We derive the formation epoch of dwarf galaxies, and we find that dwarf
galaxies make a significant contribution to the total neutral gas density in
DLAs, and that this contribution is more important at high redshifts (z > 2-3).
We propose a scenario in which the DLA population is dominated by dwarf
galaxies at high redshifts and by disks at lower redshifts. We also find that
Lyman Break Galaxies (LBGs) may constitute a sequence rather than present a
sharp dichotomy between the two populations. We also arise the possibility that
we could be missing a whole population of high HI density column objects, with
metallicities intermediate between those of DLAs and LBGs. Finally, we discuss
the possibility that relying only on the observations of DLAs could lead to an
underestimate of the metal content of the high redshift Universe.


title: Physical Processes in Strong Magnetic Fields of Neutron Stars

abstract:
  Neutron stars have inferred surface magnetic fields of up to 10^{14} Gauss,
in the case of radio pulsars, and up to possibly 10^{15} Gauss, in the case of
Soft Gamma-Ray Repeaters and Anomalous X-ray Pulsars. In fields this high, QED
effects will profoundly change the characteristics of continuum radiation
processes such as synchrotron emission and Compton scattering and will also
allow the possibility of additional physical processes such as one-photon pair
production, vacuum polarization and photon splitting. Atomic line processes
will also be significantly affected by the presence of strong fields. I will
review some of the properties of radiation processes in strong magnetic fields
that are most relevant to pulsars, SGRs and AXPs and the role they play in
models for these sources.


title: High Energy Emission from the Polar Cap: The Slot Gap Revisited

abstract:
  The characteristics of the high-energy emission from polar cap accelerators
will be discussed. Particles accelerated in the "slot gap" near the polar cap
rim will reach altitudes of several stellar radii before initiating pair
cascades, producing a wide hollow cone of emission in young pulsars and some
millisecond pulsars. Model X-ray and gamma-ray spectra and pulse profiles,
based on Monte-Carlo simulations of polar cap pair cascades, will be presented.


title: Obscured Active Galactic Nuclei and Obscured Accretion

abstract:
  Most of the local active galactic nucleus (AGN) population is obscured and
much of the X-ray background originates in obscured AGNs. The contribution of
obscured accretion to the growth of massive black holes is discussed here. The
recent identification of significant samples of the X-ray sources that dominate
the X-ray background intensity has shown a redshift peak at 0.7-0.8, rather
than the redshift of 2 found for bright optical quasars. Obscured accretion has
a faster evolution than unobscured accretion. The lower redshift and luminosity
of most obscured AGNs mean that although they dominate the absorption-corrected
intensity of the X-ray background by a factor of about 3 over unobscured
objects, they make only an equal contribution to the local mass density in
black holes. Obscured and unobscured AGNs together contribute about 4 x 10^5
Msun/Mpc^3. Type 2 quasars and Compton-thick objects may give another 10^5
Msun/Mpc^3, but no more unless direct determinations from the M-sigma relation
seriously underestimate the local black hole mass density, or unless most
massive black holes are rapidly spinning (so having a higher radiative
efficiency than the 10% assumed above). Obscured accretion probably dominates
the growth of black holes with masses below a few times 10^8 Msun, whereas
optically bright quasars dominate at higher masses. The luminosity absorbed by
the dusty gas in obscured AGNs is reradiated in the mid-infrared and
far-infrared bands. The contribution of AGNs drops from about 20% of the
mid-infrared background to just a few percent of the far-infrared background.


title: Modelling the nova rate in galaxies

abstract:
  We compute theoretical nova rates as well as type Ia SN rates in galaxies of
different morphological type (Milky Way, ellipticals and irregulars) by means
of detailed chemical evolution models, and compare them with the most recent
observations. The main difference among the different galaxies is the assumed
history of star formation. In particular, we predict that the nova rates in
giant ellipticals such as M87 are 100-300 nova/yr, about a factor of ten larger
than in our Galaxy (25 nova/yr), in agreement with very recent estimates from
HST data. The best agreement with the observed rates is obtained if the
recurrence time of novae in ellipticals is assumed to be longer than in the
Milky Way. This result indicates that the star formation rate in ellipticals,
and in particular in M87, must have been very efficient at early cosmic epochs.
We predict a nova rate for the LMC of 1.7 nova/yr, again in agreement with
observations. We compute also the K- and B-band luminosities for ellipticals of
different luminous mass and conclude that there is not a clear trend for the
luminosity specific nova rate with luminosity among these galaxies. However,
firm conclusions about ellipticals cannot be drawn because of possible
observational biases in observing these objects. The comparison between the
specific nova rates in the Milky Way and the LMC indicates a trend of
increasing nova rate passing from the Galaxy towards late-type spirals and
Magellanic irregulars.


title:
A Molecular Einstein Ring: Imaging a Starburst Disk Surrounding a
  Quasi-Stellar Object

abstract:
  Images of the CO 2-1 line emission, and the radio continuum emission, from
the redshift 4.12 gravitationally lensed quasi-stellar object (QSO) PSS
J2322+1944 reveal an Einstein ring with a diameter of 1.5". These observations
are modeled as a star forming disk surrounding the QSO nucleus with a radius of
2 kpc. The implied massive star formation rate is 900 M_sun/year. At this rate
a substantial fraction of the stars in a large elliptical galaxy could form on
a dynamical time scale of 10^8 years. The observation of active star formation
in the host galaxy of a high-redshift QSO supports the hypothesis of coeval
formation of supermassive black holes and stars in spheroidal galaxies.


title:
Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of
  Sagittarius A*

abstract:
  We investigate radiatively inefficient accretion flow models for Sgr A*, the
supermassive black hole in our Galactic Center, in light of new observational
constraints. Confirmation of linear polarization in the submm emission argues
for accretion rates much less than the canonical Bondi rate. We consider models
with low accretion rates and calculate the spectra produced by a hybrid
electron population, consisting of both thermal and nonthermal particles. The
thermal electrons produce the submm emission and can account for its linear
polarization properties. As noted in previous work, the observed low-frequency
radio spectrum can be explained if a small fraction ($\approx 1.5$%) of the
electron thermal energy resides in a soft power-law tail. In the innermost
region of the accretion flow, turbulence and/or magnetic reconnection events
may occasionally accelerate a fraction of the electrons into a harder power-law
tail. We show that the synchrotron emission from these electrons, or the
Compton up-scattering of synchrotron photons by the same electrons, may account
for the X-ray flares observed by {\it Chandra}.


title: X-ray flares from Sgr A*: star-disk interactions?

abstract:
  Sgr A*, the putative black hole in our Galactic Center (GC), is extraordinary
dim in all frequencies. Apparently the black hole is unable to accrete at the
Bondi accretion rate for some reason. Another mystery of Sgr A* is the recently
discovered large magnitude and short duration X-ray flares (Baganoff et al.
2001). Here we point out that X-ray flares should be expected from star
passages through an inactive (i.e. formerly accreting) disk. There are
thousands of stars in Sgr A* stellar cluster, and each star will pass through
the disk twice per orbit. A shock hot enough to emit X-rays is formed around
the star when the latter is inside the disk. We develop a simple yet somewhat
detailed model for the X-ray emission from the shock. The duration of the
flares, their X-ray spectra, frequency of events, and weakness of emission in
the radio and near infra-red appear to be consistent with the available
observations of X-ray flares. We therefore suggest that at least a fraction of
the observed flares is due to the star-disk passages. Such star-disk flares are
also of interest in the nuclei of nearby inactive galaxies, especially in
connection with perspective Constellation-X and XEUS X-ray missions.


title: Locating the Launching Region of T Tauri Winds: The Case of DG Tau

abstract:
  It is widely believed that T Tauri winds are driven magnetocentrifugally from
accretion disks close to the central stars. The exact launching conditions are
uncertain. We show that a general relation exists between the poloidal and
toroidal velocity components of a magnetocentrifugal wind at large distances
and the rotation rate of the launching surface, independent of the uncertain
launching conditions. We discuss the physical basis of this relation and verify
it using a set of numerically-determined large-scale wind solutions. Both
velocity components are in principle measurable from spatially resolved
spectra, as has been done for the extended low-velocity component (LVC) of the
DG Tau wind by Bacciotti et al. For this particular source, we infer that the
spatially resolved LVC originates from a region on the disk extending from
$\sim 0.3$ to $\sim 4.0\AU$ from the star, which is consistent with, and a
refinement over, the previous rough estimate of Bacciotti et al.


title:
The Lack of BLR in Low Accretion Rate AGN as Evidence of their Origin in
  the Accretion Disk

abstract:
  In this paper we present evidence suggesting that the absence or presence of
Hidden Broad Line Regions (HBLRs) in Seyfert 2 galaxies is regulated by the
rate at which matter accretes onto a central supermassive black hole, in units
of Eddington rate. We use the intrinsic (i.e. unabsorbed) X-ray luminosities of
these sources and their black hole masses (estimated by using the well known
relationship between nuclear mass and bulge luminosity in galaxies) to derive
the nuclear accretion rate in units of Eddington. We find that virtually all
HBLR sources have accretion rate larger than a threshold value of
$\dot{m}_{thres} \simeq 10^{-3}$ (in Eddington units), while non-HBLR sources
lie at $\dot{m} \ls \dot{m}_{thres}$.
  These data nicely fit predictions from a model proposed by Nicastro (2000),
in which the Broad Line Regions (BLRs) are formed by accretion disk
instabilities occurring in proximity of the critical radius at which the disk
changes from gas pressure dominated to radiation pressure dominated. This
radius diminishes with decreasing accretion rates; for low enough accretion
rates (and therefore luminosities), the critical radius becomes smaller than
the innermost stable orbit, and BLRs cannot form.


title:
Reasoning From Fossils: Learning From the Local Black Hole Population
  About the Evolution of Quasars

abstract:
  We discuss a simple model for the growth of supermassive black holes (BHs) at
the center of spheroidal stellar systems. In particular, we assess the
hypotheses that (1) star formation in spheroids and BH fueling are proportional
to one another, and (2) the BH accretion luminosity stays near the Eddington
limit during luminous quasar phases. With the aid of this simple model, we are
able to interpret many properties of the QSO luminosity function, including the
puzzling steep decline of the characteristic luminosity from redshift z=2 to to
z=0: indeed the residual star formation in spheroidal systems is today limited
to a small number of bulges, characterized by stellar velocity dispersions a
factor of 2-3 smaller those of the elliptical galaxies hosting QSOs at z > 2. A
simple consequence of our hypotheses is that the redshift evolution of the QSO
emissivity and of the star formation history in spheroids should be roughly
parallel. We find this result to be broadly consistent with our knowledge of
the evolution of both the global star formation rate, and of the evolution of
the QSO emissivity, but we identify interesting discrepancies at both low and
high redshifts, to which we offer tentative solutions. Finally, our hypotheses
allow us to present a robust method to derive the duty cycle of QSO activity,
based on the observed QSO luminosity function, and on the present-day relation
between the masses of supermassive BHs and those of their spheroidal host
stellar systems. The duty cycle is found to be substantially less than unity,
with characteristic values in the range (3-6)x10^(-3), and we compute that the
average bolometric radiative efficiency is epsilon=0.07. Finally, we find that
the growth in mass of individual black holes at high redshift (z>2) can be
dominated by mergers, and is therefore not necessarily limited by accretion.


title:
A method to infer the stellar population that dominated the UV
  background at the end of reionization

abstract:
  We present an observational test of the spectrum of the ionizing background
at z~5; the test is sufficiently sensitive to determine whether Pop II or Pop
III stars are the dominant source of ionizing radiation. The ionizing
background at z~5 may reflect the nature of the sources responsible for the
final overlap phase of reionization. We find that rest-frame extreme-UV HeI
absorption will be detectable in deep spectral observations of some rare z~5
quasars; the ratio of HeI to HI absorption reflects the shape of the ionizing
background in the photon energy range between 13.6 and 24.6 eV. Most z~5
quasars have too much HI absorption along their line of sight for HeI
absorption to be observed. However, based on current measurements of HI
absorber statistics, we use Monte Carlo simulations to demonstrate that the
Sloan Digital Sky Survey (SDSS) will discover a sufficient number of z~5
quasars to turn up a quasar suitable for measuring HeI absorption (and we
illustrate a selection method to identify that quasar). From simulated
observations of a suitable z~5 quasar with a 10-meter telescope, we show that a
constraint on the spectral slope of the ionizing background at that redshift
can be obtained.


title:
The First Nonlinear Structures and the Reionization History of the
  Universe

abstract:
  In cosmological models favored by current observations, the first
astrophysical objects formed in dark matter halos at redshifts starting at
z>20, and their properties were determined by primordial H_2 molecular
chemistry. These protogalaxies were very abundant, but substantially less
massive than typical galaxies in the local Universe. Extreme metal-poor stars,
and massive black holes in their nuclei reionized the bulk of the hydrogen in
the intergalactic medium. Reionization may have taken place over an extended
redshift interval, ending around z=7. Observational probes of the process of
reionization are afforded by studying the polarization of the cosmic microwave
background anisotropies, as well as by studying the spectra and abundance of
distant Lyman alpha-emitting galaxies. Here we review theoretical expectations
on how and when the first galaxies formed, and summarize future observational
prospects of probing hydrogen reionization.


title: Jet Collimation in Action: Re-alignment on Kiloparsec Scales in 3C279

abstract:
  We report a change in the trajectory of a well studied jet component of the
quasar 3C279. The component changes in apparent projected speed and direction,
and we find it to be moving with a Lorentz factor gamma >~ 15 at an initial
angle of <~ 1 degree to the line of sight. The new trajectory of the component
has approximately the same speed and direction as an earlier superluminal
feature, originally seen in the early 1970s. The new direction for the
component is also much better aligned with larger scale VLBA and VLA structure
out to 0.1 arcseconds. We suggest that the trajectory change is a collimation
event occurring at >~ 1 kiloparsec (deprojected) along the jet. While the
change in trajectory on the sky appears to be 26 degrees the intrinsic change
is <~ 1 degree. We estimate the Doppler factor prior to the change in direction
to be D >~ 28 and after the change to be D >~ 23. Comparison to independent
constraints on the Doppler factor suggest that the energy in the radiating
particles cannot greatly exceed the energy in the magnetic field unless the
volume filling factor is very much less than one.


title: BeppoSAX average spectra of Seyfert galaxies

abstract:
  We have studied the average 3-200 keV spectra of Seyfert galaxies of type 1
and 2, using data obtained with BeppoSAX. The average Seyfert 1 spectrum is
well-fitted by a power law continuum with photon spectral index Gamma~1.9, a
Compton reflection component R~0.6-1 (depending on the inclination angle
between the line of sight and the reflecting material) and a high-energy cutoff
at around 200 keV; there is also an iron line at 6.4 keV characterized by an
equivalent width of 120 eV. Seyfert 2's on the other hand show stronger neutral
absorption (NH=3-4 x 10^{22} atoms cm-2) as expected but are also characterized
by an X-ray power law which is substantially harder (Gamma~1.75) and with a
cut-off at lower energies (E_c~130 keV); the iron line parameters are instead
substantially similar to those measured in type 1 objects. There are only two
possible solutions to this problem: to assume more reflection in Seyfert 2
galaxies than observed in Seyfert 1 or more complex absorption than estimated
in the first instance. The first possibility is ruled out by the Seyfert 2 to
Seyfert 1 ratio while the second provides an average Seyfert 2 intrinsic
spectrum very similar to that of the Seyfert 1. The extra absorber is likely an
artifact due to summing spectra with different amounts of absorption, althought
we cannot exclude its presence in at least some individual sources. Our result
argues strongly for a very similar central engine in both type of galaxies as
expected under the unified theory.


title:
Hard X-ray Flares Preceding Soft X-ray Outbursts in Aquila X-1: A Link
  between Neutron Star and Black Hole State Transitions

abstract:
  We have analyzed {\it Rossi X-ray Timing Explorer} (RXTE) data of the neutron
star transient Aquila X-1 obtained during its outbursts in May/June 1999 and
September/October 2000. We find that in the early rise of these outbursts, a
hard flare in the energy range above 15 keV preceded the soft X-ray peak. The
hard X-ray flux of the hard flares at maximum was more than a factor of three
stronger than at any other point in the outbursts. The rise of the hard X-ray
flare to this maximum, was consistent with a monotonically brightening low/hard
state spectrum. After the peak of the hard flare, a sharp spectral transition
occurred with spectral pivoting in the range 8--12 keV. Our timing analysis
shows that during the hard flare the power spectra were mainly composed of
band-limited noise and a $\sim$ 1--20 Hz QPO, which correlate in frequency.
Immediately after the hard flare, the power spectra turned into power law
noise. The spectral and timing properties during and after the hard flares are
very similar to those in black hole transients during the early rise of an
outburst. We suggest that these hard flares and spectral transitions in Aql X-1
are of the same origin as those observed in black hole transients. This leads
to the association of the 1--20 Hz QPOs and band-limited noise in Aql X-1 with
those in black hole transients. We discuss the impact of this discovery on our
understanding of soft X-ray transient outbursts, state transitions and
variability in X-ray binaries.


title: Probing the X-ray Variability of X-ray Binaries

abstract:
  Kilohertz quasi-periodic oscillations (kHz QPOs) has been regarded as
representing the Keplerian frequency at the inner disk edge in the neutron star
X-ray binaries. The so-called ``parallel tracks'' on the plot of the kHz QPO
frequency vs. X-ray flux in neutron star X-ray binaries, on the other hand,
show the correlation between the kHz QPO frequency and the X-ray flux on time
scales from hours to days. This is suspected as caused by the variations of the
mass accretion rate through the accretion disk surrounding the neutron star. We
show here that by comparing the correlation between the kHz QPO frequency and
the X-ray count rate on a certain QPO time scale observed approximately
simultaneous in the Fourier power spectra of the X-ray light curve, we have
found evidences that the X-ray flux of millihertz QPOs in neutron star X-ray
binaries is generated inside the inner disk edge if adopting that the kilohertz
QPO frequency is an orbital frequency at the inner disk edge. This approach
could be applied to other variability components in X-ray binaries.


title:
Atomic gas far away from the Virgo cluster core galaxy NGC 4388. A
  possible link to isolated star formation in the Virgo cluster?

abstract:
  We have discovered 6 10^7 M_{\odot} of atomic gas at a projected distance
greater than 4' (20 kpc) from the highly inclined Virgo spiral galaxy NGC 4388.
This gas is most probably connected to the very extended H\alpha plume detected
by Yoshida et al. (2002). Its mass makes a nuclear outflow and its radial
velocity a minor merger as the origin of the atomic and ionized gas very
unlikely. A numerical ram pressure simulation can account for the observed HI
spectrum and the morphology of the H\alpha plume. An additional outflow
mechanism is still needed to reproduce the velocity field of the inner H\alpha
plume. The extraplanar compact HII region recently found by Gerhard et al.
(2002) can be explained as a stripped gas cloud that collapsed and decoupled
from the ram pressure wind due to its increased surface density. The
star-forming cloud is now falling back onto the galaxy.


title:
PLANCK/LFI: an Advanced Multi-beam High Performance mm-wave Optics for
  Space Applications

abstract:
  The Low Frequency Instrument (LFI) is one of the two instruments onboard the
ESA PLANCK satellite foreseen to be launched in 2007. The LFI will image the
Cosmic Microwave Background (CMB) anisotropies and the polarization in four
different bands, with an unprecedented combination of sky coverage, calibration
accuracy, control of systematic errors, and sensitivity. LFI is coupled to the
PLANCK Telescope by an array of 23 high performance dual profiled corrugated
feed horns. The dual reflector off axis-design of the 1.5 meter projected
aperture telescope is the most advanced optical design ever conceived for
accommodating large multi-beam and multi-frequency focal plane units. The
location and the design of the feed horns, for both instruments, have been
optimised in order to maintain good beam symmetry, even far from the optical
axis, and an excellent straylight rejection. In this paper we describe the LFI
instrument with emphasis on its optical performance and coupling with the
PLANCK telescope.


title:
INTEGRAL Spectroscopy of IRAS 17208-0014: Implications for the
  Evolutionary Scenarios of Ultraluminous Infrared Galaxies

abstract:
  New integral field optical fiber spectroscopy obtained with the INTEGRAL
system, together with archival {\it {\it HST}} WFPC2 and NICMOS images, have
been used to investigate the ultraluminous infrared galaxy IRAS 17208$-$0014,
one of the coldest and most luminous objects in the IRAS 1 Jy sample. The 2D
gas velocity field identifies the {\it optically faint} K-band nucleus as the
{\it true} dynamical nucleus of the galaxy, and shows that the 3 kpc, tilted (i
$\sim$ 35 degree) disk is rotating at $\Delta$Vsin$i$= 250 km s$^{-1}$. The
kinematical, morphological and photometric evidence presented here supports the
idea that in IRAS 17208-0014 we are witnessing a luminous, cool ULIRG which is
at the final coalescence phase of a system composed of two spirals with m
$\leq$ m$^*$, a mass ratio of 2:1, each consisting of a disk+bulge internal
structure, that have been involved in a prograde encounter. This system will
most likely evolve into an intermediate-mass ($\sim$ L$^*$) elliptical. The
multifrequency empirical evidence gathered so far shows no trace of a luminous
QSO, and indicates that starbursts dominate the energy output in this galaxy.
Therefore IRAS 17208$-$0014 questions the universality of the ULIRG to QSO
evolutionary scenario proposed by Sanders and collaborators, and supports the
one recently proposed by Colina et al, where two low mass disk galaxies would
produce luminous cool ULIRGs that would not evolve into a QSO phase. (abridge)


title: An XMM Observation of IGR J16320-4751=AX J1631.9-4752

abstract:
  The hard X-ray sensitivity and arcminute position accuracy of the recently
launched International Gamma-Ray Laboratory (INTEGRAL) has lead to the
(re-)discovery of a class of heavily absorbed hard X-ray sources lying in the
Galactic plane. We report on the analysis of an XMM observation of such a
source IGR J16320-4751 = AX J1631.9-4752. Our analysis allowed us to obtain the
most accurate X-ray position to date (Rodriguez et al. 2003), and to identify a
likely infrared counterpart (Tomsick et al. 2003). We present the detailed
analysis of the IGR J1632-4751 XMM spectra. The PN spectrum can be well
represented by a single powerlaw or a comptonized spectrum with a high
equivalent absorption column density of ~ 2 x10^{23} cm^{-2}. The current
analysis and the comparison with the properties of other sources favor the
possibility that the source is a Galactic X-Ray Binary (XRB). The
identification of two candidate IR counterparts is in good agreement with this
identification. The hard spectrum previously seen with ASCA, and the brightness
of the candidate counterparts indicate that IGR J1632-4751 is most probably a
highly absorbed High Mass X-ray Binary, hosting a neutron star.


title:
An empirical test of the theoretical population corrections to the Red
  Clump absolute magnitude

abstract:
  The mean absolute magnitude of the local red clump (RC) is a very well
determined quantity due to the availability of accurate HIPPARCOS parallaxes
for several hundred RC stars, potentially allowing it to be used as an accurate
extra-galactic distance indicator. Theoretical models predict that the RC mean
magnitude has non-linear dependencies on both age and metallicity. This
suggests that a population correction, based on the star formation rate (SFR)
and age-metallicity relation (AMR) of a particular system, should be applied to
the local RC magnitude before it can be compared to the RC in that system in
order to make a meaningful distance determination. Using a sample of 8 Galactic
open clusters and the GC 47 Tuc, we determine the cluster distances, and hence
the RC absolute magnitude in V, I and K, by applying our empirical main
sequence fitting method, which utilizes a large sample of local field dwarfs
with accurate HIPPARCOS parallaxes. The age and metallicity range of these 9
clusters enable us to make a quantitative assessment of the age and metallicity
dependencies of the population corrections predicted by the theoretical models
of Girardi & Salaris (2001). We find excellent agreement between the empirical
data and the models in all 3 pass-bands, with no statistically significant
trends or offsets, thus fully confirming the applicability of the models to
single-age, single-metallicity stellar populations. Since, from the models, the
population correction is a complicated function of both metallicity and age, if
this method is used to derive distances to composite populations, it is
essential to have an accurate assessment of the SFR and AMR of the system in
question, if errors of several tenths of a magnitude are to be avoided.


title: Young isolated neutron stars from the Gould Belt

abstract:
  The origin of the local population of young, cooling neutron stars is
investigated with a population synthesis model taking into account the
contribution of neutron stars born in the Gould Belt, in addition to those
originating in the Galactic disk. We estimate their emission in the soft X-ray
band as a function of distance and age and construct the Log N -- Log S
distribution. It is shown that the inclusion of neutron stars from the Gould
Belt provides a good fit to the observed Log N -- Log S distribution. As the
Sun is situated inside the Gould Belt, one can naturally explain the
comparative local overabundance of massive progenitors and can remove the
difficulty of the deficit of relatively bright ($\ga 0.1$ ROSAT PSPC cts
s$^{-1}$) cooling neutron stars previously reported from models where only
neutron stars from the Galactic disk were accounted for.


title:
Advanced simulation techniques for straylight prediction of high
  performance mm-wave reflecting telescope

abstract:
  The prediction of the antenna radiation pattern can be extremely complex for
antenna system composed of several reflector surfaces. Typically, at
mm-wavelengths, telescopes are composed of mirrors and shields, and an accurate
prediction of the whole system response is therefore complicated. This is the
case for the optical system of the ESA Planck mission. Planck represents the
third generation of mm-wave instruments designed for space observations of CMB
anisotropies over the whole sky, and has unprecedented sensitivity and angular
resolution. The Low Frequency Instrument (LFI) is one of the two instruments
onboard the satellite. LFI consists of an array of 46 cooled HEMT-based
receivers coupled to the 1.5 meter off-axis dual reflector telescope by an
array of 23 dual profiled corrugated feed horns working at four frequencies
between 30 and 100 GHz. Owing to the small level of CMB anisotropies, the
control of the systematic effects is mandatory, and this is assured by means of
a dedicated instrument design and by an accurate knowledge of instrument
characteristics. The telescope is a source of systematic errors both in the
main beam region (aberrations) and in the sidelobes region (straylight
contamination) and efficient and accurate radiation pattern simulations of the
telescope-feed system are needed. We report on the simulations of the full
pattern applied to the Planck/LFI-Telescope system. These simulations, based on
advanced GTD methods, are used to evaluate the straylight rejection of the
entire optical system, by applying a new approach for evaluating the sidelobes
in a rigorous way, even at very low levels.


title: Long Period Variables detected by ISO in the SMC

abstract:
  This article presents the study of the light-curves extracted from the MACHO
database of a sample of stars observed by the ISO in the SMC. These stars
belong to the ISO-Mini-Survey catalogue of the Magellanic Clouds (ISO-MCMS,
Loup et al. in preparation). Most of them are in the AGB and supergiant phases.
The dominant period and amplitude of pulsation have been derived and the stars
have been classified as Mira or Semi-Regular pulsators. Furthermore, the
cross-identification with near-infrared DENIS and 2MASS magnitudes available
within the ISO-MCMS allowed us: (i) to investigate the properties of these
stars in the combined near- and mid-infrared colour-magnitude diagrams, (ii) to
derive the bolometric magnitude by integrating the spectral energy distribution
and (iii) to estimate the mass-loss rate. The stars have been divided into
carbon- (C-) and oxygen-rich (O-rich) using the (J-Ks, Ks) colour-magnitude
diagram and their period and amplitude distributions have been compared. C-rich
AGB stars have a sharp peak in their period distribution at about 250 days and
have on average a larger amplitude than O-rich AGB stars. This effect, not
previously detected from the study of similar stars in the LMC and in the
Baade's window, might be closely related to the metallicity of the environment
in which the stars have formed.


title:
Light curves and H$\alpha$ luminosities as indicators of $^{56}$Ni mass
  in type IIP supernovae

abstract:
  The possibility is investigated that the H$\alpha$ luminosity at the nebular
epoch may be an additional indicator of $^{56}$Ni mass in type II supernovae
with plateau (SNe IIP), on the basis of available photometry and spectra. We
first derive the $^{56}$Ni mass from the $M_V$ magnitude on the radioactive
tail using a standard approach. A confirmation of the correlation between
$^{56}$Ni mass and plateau $M_V$ magnitude found recently by Hamuy (2003) is
evident. There is strong evidence of a correlation between steepness of the $V$
light curve slope at the inflection time and the $^{56}$Ni mass. If confirmed,
this relation may provide distance and extinction independent estimates of the
amount of $^{56}$Ni in SNe IIP. We then apply upgraded radioactive models of
H$\alpha$ luminosity at the nebular epoch and claim that it may be a good
indicator of $^{56}$Ni, if mass, energy and mixing properties vary moderately
(within factor $\sim 1.4$) among SNe IIP . This method of the $^{56}$Ni mass
determination from H$\alpha$ luminosities yields results which are consistent
with the photometric mass of $^{56}$Ni mass to within 20%. This result also
implies that the parameters of SNe IIP events (mass, energy and mixing
properties) are rather similar among the majority of SNe IIP, except for rare
cases of SN II intermediate between IIP and IIL (linear), of which SN 1970G is
an example.


title: Radio Emission from SN 2001gd in NGC 5033

abstract:
  We present the results of monitoring the radio emission from the Type IIb
supernova SN 2001gd between 2002 February 8 and 2002 October 28. Most of the
data were obtained using the Very Large Array at the five wavelengths of
$\lambda \lambda$1.3 cm (22.4 GHz), 2.0 cm (14.9 GHz), 3.6 cm (8.44 GHz), 6.2
cm (4.86 GHz), and 21 cm (1.4 GHz). Observations were also made with Giant
Meterwave Radio Telescope at $\lambda$21 cm (1.4 GHz). The object was
discovered optically well after maximum light, making any determination of the
early radio evolution difficult. However, subsequent observations indicate that
the radio emission has evolved regularly in both time and frequency and is well
described by the SN shock/circumstellar medium interaction model.


title: Planck Low Frequency Instrument: Beam Patterns

abstract:
  The Low Frequency Instrument on board the ESA Planck satellite is coupled to
the Planck 1.5 meter off-axis dual reflector telescope by an array of 27
corrugated feed horns operating at 30, 44, 70, and 100 GHz. We briefly present
here a detailed study of the optical interface devoted to optimize the angular
resolution (10 arcmin at 100 GHz as a goal) and at the same time to minimize
all the systematics coming from the sidelobes of the radiation pattern. Through
optical simulations, we provide shapes, locations on the sky, angular
resolutions, and polarization properties of each beam.


title:
The XMM-Newton EPIC Background: Production of Background Maps and Event
  Files

abstract:
  XMM-Newton background maps for the 3 EPIC instruments in their different
instrument/mode/filter combinations and in several energy bands have been
constructed using a superposition of 72 pointed observations. Event datasets,
with point sources excised, for the different instrument/mode/filter
combinations have also been assembled, with longer exposure times than
previously available files. The construction of the background maps and event
files, together with their properties and usage are described here. Also given
are statistical properties of the photon and particle components of the
XMM-Newton EPIC background, based on the analysis of the 72 datasets.


title: Combined and Comparative Time-Series Spectrum Analysis

abstract:
  It is often necessary to compare the power spectra of two or more time
series. One may, for instance, wish to estimate what the power spectrum of the
combined data sets might have been. One might also wish to estimate the
significance of a particular peak that shows up in two or more power spectra.
Visual comparison can be revealing, but it can also be misleading. This leads
one to look for one or more ways of forming statistics, which lend themselves
to significance estimation, from two or more power spectra. We here propose two
such statistics, one that is most useful for the combined study of two or more
similar time series, and another that is more useful for the study of
dissimilar time series.


title: Homogeneity of early--type galaxies across clusters

abstract:
  We studied the scatter across clusters of the color of the red sequence in a
representative and large sample of clusters (more than 200) detected on the
Early Data Release of the Sloan Digital Sky Survey (EDR--SDSS) in the redshift
range 0.06<z<0.34. We found an extreme degree of homogeneity in the color of
the red sequence (the intrinsic scatter is about 0.02 to 0.03 mag) suggesting
that either galaxies on the red sequence formed a long time ago (z>2) or else
their star formation is universally delayed with preservation of a small spread
in age formation. The latter possibility is ruled out by the mere existence of
galaxies at high redshift. While the old age of ellipticals was already been
claimed for a small heterogeneous collection of clusters, most of which are
rich ones, we found that it holds for a ten to one hundred larger sample,
representative of all clusters and groups detected on the EDR--SDSS. Hence, we
claim the possible universality of the color of the galaxies on the red
sequence. Furthermore, the sample includes a large number of very poor clusters
(also called groups), not studied in previous works, for which the hierarchical
and monolithic scenarios of elliptical formation predict different colors for
the brightest ellipticals. The observed red sequence color does not depend on
cluster/group richness at a level of 0.02 mag, while a 0.23 mag effect is
expected according to the hierarchical prediction. Therefore, the stellar
population of red sequence galaxies is similar in clusters and groups, in spite
of different halo histories. Finally, we propose the use of color of the red
sequence as distance indicator. (Abridged)


title: The Evolution of Quasars

abstract:
  This article reviews and discusses 1) the discovery and early work on the
evolution of quasars and AGNs, 2) the different techniques used to find quasars
and their suitability for evolutionary studies, 3) the current status of our
knowledge of AGN evolution for 0 < z < 6, 4) the new results and questions that
deep radio and X-ray surveys are producing for the subject, 5) the relation of
AGNs to massive black holes being found in local galaxies and what they tell us
about both galaxy and AGN evolution, and 6) current research problems and
future directions in quasar and AGN evolution.


title: 3D weak lensing

abstract:
  I propose an analysis method, based on spin-spherical harmonics and spherical
Bessel functions, for large-scale weak lensing surveys which have source
distance information through photometric redshifts. I show that the distance
information can significantly reduce statistical errors on cosmological
parameters; in particular, 3D lensing analysis offers excellent prospects for
constraining the equation of state of the vacuum energy which dominates the
energy density of the Universe. I show that the ratio of pressure to energy
density could be determined to an accuracy of $\sim 1%$ or better. Having
distance information also offers significant advantages in the control of
systematic effects such as the intrinsic alignment of galaxies. The case for
obtaining photometric redshifts is therefore compelling. A signal-to-noise
eigenmode analysis of the modes shows that the modes with highest
signal-to-noise correspond quite closely to ignoring the redshift information,
but there is significant extra information from a few radial modes. These modes
are generally long-wavelength, suggesting that useful information can be
gleaned even if the photometric redshifts are relatively inaccurate.


title:
The effect of collisional enhancement of Balmer lines on the
  determination of the primordial helium abundance

abstract:
  This paper describes a new determination of the primordial helium abundance
(Y_P), based on the abundance analysis of five metal-poor extragalactic HII
regions. For three regions of the sample (SBS 0335-052, I Zw 18, and H29) we
present tailored photoionization models based on improved calculations with
respect to previous models. In particular, we use the photoionization models to
study quantitatively the effect of collisional excitation of Balmer lines on
the determination of the helium abundance (Y) in the individual regions. This
effect is twofold: first, the intensities of the Balmer lines are enhanced with
respect to the pure recombination value, mimicking a higher hydrogen abundance;
second, the observed reddening is larger than the true extinction, due to the
differential effect of collisions on different Balmer lines. In addition to
these effects, our analysis takes into account the following features of HII
regions: (i) the temperature structure, (ii) the density structure, (iii) the
presence of neutral helium, (iv) the collisional excitation of the HeI lines,
(v) the underlying absorption of the HeI lines, and (vi) the optical thickness
of the HeI lines. The object that shows the highest increase in Y after the
inclusion of collisional effects in the analysis is SBS 0335-052, whose helium
abundance has been revised by Delta Y = +0.0107. The revised Y values for the
five objects in our sample yield an increase of +0.0035 in Y_P, giving Y_P =
0.2391 +/- 0.0020.


title: Large frequency drifts during Type I X-ray bursts

abstract:
  We study the spin-down of a neutron star atmosphere during the Type I X-ray
burst in low mass X-ray binaries. Using polar cap acceleration models, we show
that the resulting stellar ``wind'' torque on the burning shell due to the
flowing charged particles (electrons, protons and ions) from the star's polar
caps may change the shell's angular momentum during the burst. We conclude that
the net change in the angular momentum of the star's atmosphere can account for
rather large frequency drifts observed during Type I X-ray burst.


title: Starburst and AGN activity in ultraluminous infrared galaxies

abstract:
  (Abridged) We examine the power source of 41 local Ultraluminous Infrared
Galaxies using archival infrared and optical photometry. We fit the observed
Spectral Energy Distributions (SEDs) with starburst and AGN components; each
component being drawn from a family of templates. We find all of the sample
require a starburst, whereas only half require an AGN. In 90% of the sample the
starburst provides over half the IR emission, with a mean fractional luminosity
of 82%. When combined with other galaxy samples we find that starburst and AGN
luminosities correlate over 6 decades in IR luminosity suggesting that a common
factor governs both luminosities, plausibly the gas masses in the nuclear
regions. We find that the mid-IR 7.7 micron line-continuum ratio is no
indication of the starburst luminosity, or the fractional AGN luminosity, and
therefore that this ratio is not a reliable diagnostic of the power source in
ULIRGs. We propose that the scatter in the radio-IR correlation in ULIRGs is
due to a skewed starburst IMF and/or relic relativistic electrons from a
previous starburst, rather than contamination from an obscured AGN. We show
that most ULIRGs undergo multiple starbursts during their lifetime, and by
inference that mergers between more than two galaxies may be common amongst
ULIRGs. Our results support the evolutionary model for ULIRGs proposed by
Farrah et al 2001, where they can follow many different evolutionary paths of
starburst and AGN activity in transforming merging spiral galaxies into
elliptical galaxies, but that most do not go through an optical QSO phase. The
lower level of AGN activity in our local sample than in z~1 HLIRGs implies that
the two samples are distinct populations. We postulate that different galaxy
formation processes at high-z are responsible for this difference.


title:
The spectral-curvature parameter: an alternative tool for the analysis
  of synchrotron spectra

abstract:
  The so-called Spectral Curvature Parameter(SCP), when plotted versus the
high-frequency spectral index ($alpha_{high}$) of synchrotron sources, provides
crucial parameters on the continuum spectrum of synchrotron radiation without
the more complex modeling of spectral ageing scenarios. An important merit of
the SCP-$alpha$ diagram is the enhanced reliability of extracting multiple
injection spectra, $alpha_{inj}$. Different from the colour-colour diagram,
tracks of different $alpha_{inj}$s, especially when the synchrotron particles
are young, exhibit less overlap and less smearing in the SCP-$alpha$ diagram.
Three giant radio galaxies(GRGs) and a sample of Compact steep spectrum(CSS)
souces are presented. GRGs exhibit asymmetries of their injection spectral
indices $alpha_{inj}$ in the SCP-$alpha_{high}$ diagram. The obtained
$alpha_{inj}$s and the trends in the sources are cross-checked with the
literature and show remarkable confidence. Besides the spectral steepening,
spectral flattening is prominent in the radio lobes. The spectral flattening is
a clue to efficient re-acceleration processes in the lobes. It implies
interaction with the surrounding intergalactic or intra-cluster medium is an
important characteristic of GRGs. In the SW lobe of DA240, there is a clear
sign of CI and KP/JP bifurcation at the source extremity. This indicates a
highly relativistic energy transportation from the core or in situ acceleration
in this typical FR I lobe. Our analysis proves, if exists, KP spectra imply the
existence of strong $B_{sync}$ field with $B_{sync} > B_{CMB}$. In the CSS
sources, our result confirms the CI model and $B_{sync} >> B_{CMB}$. The
synchrotron self-absorption is significant in the CSS sample.


title:
Self-Regulated Growth of Supermassive Black Holes in Galaxies as the
  Origin of the Optical and X-ray Luminosity Functions of Quasars

abstract:
  We postulate that supermassive black-holes grow in the centers of galaxies
until they unbind the galactic gas that feeds them. We show that the
corresponding self-regulation condition yields a correlation between black-hole
mass (Mbh) and galaxy velocity dispersion (sigma) as inferred in the local
universe, and recovers the observed optical and X-ray luminosity functions of
quasars at redshifts up to z~6 based on the hierarchical evolution of galaxy
halos in a Lambda-CDM cosmology. With only one free parameter and a simple
algorithm, our model yields the observed evolution in the number density of
optically bright or X-ray faint quasars between 2<z<6 across 3 orders of
magnitude in bolometric luminosity and 3 orders of magnitude in comoving
density per logarithm of luminosity. The self-regulation condition identifies
the dynamical time of galactic disks during the epoch of peak quasar activity
(z~2.5) as the origin of the inferred characteristic quasar lifetime of ~10
million years. Since the lifetime becomes comparable to the Salpeter e-folding
time at this epoch, the model also implies that the Mbh-sigma relation is a
product of feedback regulated accretion during the peak of quasar activity. The
mass-density in black-holes accreted by that time is consistent with the local
black-hole mass density of ~(0.8-6.3) times 10^5 solar masses per cubic Mpc,
which we have computed by combining the Mbh-sigma relation with the measured
velocity dispersion function of SDSS galaxies (Sheth et al.~2003). Applying a
similar self-regulation principle to supernova-driven winds from starbursts, we
find that the ratio between the black hole mass and the stellar mass of
galactic spheroids increases with redshift as (1+z)^1.5 although the Mbh-sigma
relation is redshift-independent.


title:
Global solution of viscous accretion disk around rotating compact
  objects: a pseudo-general-relativistic study

abstract:
  We study the solution of viscous accretion disks around rotating
compact/central object having hard surface i.e. neutron star, strange star and
any other highly gravitating objects. We choose pseudo-Newtonian approach to
describe the relativistic accretion disk. For this purpose, the new
pseudo-Newtonian potential is used which is applicable to describe the
relativistic properties of star and its disk. As we know, the Hartle-Thorne
metric can describe geometry of star as well as the space-time out-side of it,
we use this metric for our study. This potential reproduces the marginally
stable orbit exactly as that of general relativity. It also reproduces the
marginally bound orbit and specific mechanical energy at the marginally stable
orbit with at most 4% and 10% error respectively. Using this potential we study
the global parameter space of the accretion disk. Thus, we find out the
physical parameter regime, for which the stable accretion disk can be formed
around gravitating object with hard surface. We show that with the change of
rotation to the central object, the valid disk parameter region dramatically
changes. We also show the effect of viscosity to the fluid properties of the
disk. Subsequently, we give a theoretical prediction of kHz QPO, at least for
one out of a pair, for a fast rotating compact object as 4U 1636-53.


title: Magnetic and Electric Fields around the Black Hole in Cyg X-1

abstract:
  Analysis of polarimetric observations of X-ray binary Cyg X-1/HDE 226868
including the data obtained by BTA-6m allows to estimate the magnetic field
magnitude near the inner radius of the accretion disk. The magnetic field
magnitude occurred to be $\sim 10^{8}$ G. For power law of radial dependence of
magnetic field into an accretion disk we estimates the value of an index of
power law. For the Cyg X-1/HDE 226868 system the value of this index appears
non less then two. If one accepts as a characteristic scale of a magnetic field
generation region the dyadosphere radius, one can estimate the charge magnitude
of a black hole. For Cyg X-1 this magnitude appears to be $\sim 0.01M\sqrt{G}$,
where M is a black hole mass.


title:
The complex Halpha line profile of the bright companion to PSR
  J1740-5340 in NGC 6397

abstract:
  We present a detailed study of the Halpha and He I spectral features of COM
J1740-5340 (the companion to PSR J1740-5340 in the Galactic Globular Cluster
NGC 6397), exploiting a series of high resolution spectra obtained at different
orbital phases. The Halpha absorption line shows a complex two-component
structure, revealing that optically thin hydrogen gas resides outside the Roche
lobe of COM J1740-5340. The line morphology precludes the existence of any
residual disk around the millisecond pulsar, and suggests the presence of a
stream of material going from the companion toward the neutron star. This
material never reaches the neutron star surface, being driven back by the
pulsar radiation far beyond COM J1740-5340. By analyzing the He I absorption
lines as a function of orbital phase, we infer the presence of an overheated
longitudinal strip (about 150 times narrower than it is long) on the COM
J1740-5340 surface facing the radio pulsar.


title:
The spatial clustering of radio sources in NVSS and FIRST; implications
  for galaxy clustering evolution

abstract:
  We have measured the angular correlation function of radio sources in the 1.4
GHz NVSS and FIRST surveys. Below ~6 arcminutes w(theta) is dominated by the
size distribution of radio galaxies. A model of the size distribution of radio
galaxies can account for this excess signal in w(theta). The amplitude of the
cosmological clustering of radio sources is roughly constant at A~0.001 from 3
to 40 mJy, but has increased to A~0.007 at 200 mJy. This can be explained if
powerful (FRII) radio galaxies probe more massive structures at z~1 compared to
average power radio galaxies, consistent with powerful high-z radio galaxies
generally having massive (forming) elliptical hosts in rich cluster
environments. For FRIIs we derive a spatial (comoving) correlation length of
r_0=14\pm3 h^{-1} Mpc. This is close to that measured for extremely red objects
(EROs) associated with a population of old elliptical galaxies at z~1 by Daddi
et al. (2001). Based on their similar clustering properties, we propose that
EROs and powerful radio galaxies may be the same systems seen at different
evolutionary stages. Their r_0 is ~2 times higher than that of QSOs at a
similar redshift, and comparable to that of bright ellipticals locally. This
suggests that r_0 (comoving) of these galaxies has changed little from z~1 to
z=0, in agreement with current LCDM hierarchical models for clustering
evolution of massive early-type galaxies. Alternatively, the clustering of
radio galaxies can be explained by the galaxy conservation model. This then
implies that radio galaxies of average power are the progenitors of the local
early-type field population, while the most powerful radio galaxies will evolve
into a present-day population with r_0 similar to that of local rich clusters.


title: Fabry-Perot observations of the HH 110 jet

abstract:
  We have obtained a Halpha position-velocity cube from Fabry-Perot
interferometric observations of the HH 110 flow. We analyze the results in
terms of anisotropic wavelet transforms, from which we derive the spatial
distribution of the knots as well as their characteristic sizes (along and
across the outflow axis). We then study the spatial behaviour of the line width
and the central radial velocity. The results are interpreted in terms of a
simple ``mean flow+turbulent eddy'' jet/wake model. We find that most of the
observed kinematics appear to be a direct result of the mean flow, on which are
superposed low amplitude (35 km/s) turbulent velocities.


title: Numerical Methods in Gravitational Lensing

abstract:
  Most problems in gravitational lensing require numerical solutions. The most
frequent types of problems are (1) finding multiple images of a single source
and classifying the images according to their properties like magnification or
distortion; (2) propagating light rays through large cosmological simulations;
and (3) reconstructing mass distributions from their tidal field. This lecture
describes methods for solving such problems. Emphasis is put on using
adaptive-grid methods for finding images, issues of spatial resolution and
reliability of statistics for weak lensing by large-scale structures, and
methodical questions related to shear-inversion techniques.


title: Stellar Crowding and the Science Case for Extremely Large Telescopes

abstract:
  We present a study of the effect of crowding on stellar photometry. We
develop an analytical model through which we are able to predict the error in
magnitude and color for a given star for any combination of telescope
resolution, stellar luminosity function, background surface brightness, and
distance. We test our predictions with Monte Carlo simulations of the LMC
globular cluster NGC 1835, for resolutions corresponding to a seeing-limited
telescope, the $HST$, and an AO-corrected 30-m (near diffraction limited)
telescope. Our analytically predicted magnitude errors agree with the
simulation results to within $\sim$20%. The analytical model also predicts that
errors in color are strongly affected by the correlation of crowding--induced
photometric errors between bands as is seen in the simulations. Using
additional Monte Carlo simulations and our analytical crowding model, we
investigate the photometric accuracy which 30-m and 100-m Extremely Large
Telescopes (ELTs) will be able to achieve at distances extending to the Virgo
cluster. We argue that for stellar populations work, ELTs quickly become
crowding-limited, suggesting that low--Strehl AO systems may be sufficient for
this type of science.


title: Variability and Velocity of Superluminal Sources

abstract:
  We investigate the relation between the Doppler factor determined from
variations in total flux at 22 and 37 GHz, and the apparent transverse velocity
determined from VLBA observations at 2 cm. The data are consistent with the
relativistic beaming theory for compact radio sources, in that the distribution
of beta_{app}/delta_{var}, for 30 quasars, is roughly consistent with a Monte
Carlo simulation. The intrinsic temperature appears to be ~2x10^{10} K, close
to the "equipartition value" calculated by Readhead (1994). We deduce the
distribution of Lorentz factors for a group of 48 sources; the values range up
to about gamma=40.


title:
Variability, Brightness Temperature, Superluminal Motion, Doppler
  Boosting, and Related Issues

abstract:
  We review the observations of rapid flux density variations in compact radio
sources, and discuss the inverse Compton limit to the maximum brightness
temperature of incoherent synchrotron sources in comparison with recent VLBA
observations. The apparent agreement of the theoretical brightness temperature
limit due to inverse Compton cooling and the brightness temperatures observed
by early VLBI observations appears to have been fortuitous. VLBA observations
have greatly improved the quality of the data, but many of the early issues
remain unresolved.


title: Peculiar Broad Absorption Line Quasars found in DPOSS

abstract:
  With the recent release of large (i.e., > hundred million objects),
well-calibrated photometric surveys, such as DPOSS, 2MASS, and SDSS,
spectroscopic identification of important targets is no longer a simple issue.
In order to enhance the returns from a spectroscopic survey, candidate sources
are often preferentially selected to be of interest, such as brown dwarfs or
high redshift quasars. This approach, while useful for targeted projects, risks
missing new or unusual species. We have, as a result, taken the alternative
path of spectroscopically identifying interesting sources with the sole
criterion being that they are in low density areas of the g - r and r - i
color-space defined by the DPOSS survey. In this paper, we present three
peculiar broad absorption line quasars that were discovered during this
spectroscopic survey, demonstrating the efficacy of this approach. PSS
J0052+2405 is an Iron LoBAL quasar at a redshift z = 2.4512 with very broad
absorption from many species. PSS J0141+3334 is a reddened LoBAL quasar at z =
3.005 with no obvious emission lines. PSS J1537+1227 is a Iron LoBAL at a
redshift of z = 1.212 with strong narrow Mgii and Feii emission. Follow-up high
resolution spectroscopy of these three quasars promises to improve our
understanding of BAL quasars. The sensitivity of particular parameter spaces,
in this case a two-color space, to the redshift of these three sources is
dramatic, raising questions about traditional techniques of defining quasar
populations for statistical analysis.


title: E/B Separation in CMB Interferometry

abstract:
  We study the problem of separating E and B modes in interferometric
observations of the polarization of the cosmic microwave background. The E and
B band powers and their mixings are measured from both single-dish and
interferometric mock observations using the quadratic estimator of the maximum
likelihood analysis. We find that the interferometer can separate E and B modes
in a single-pointing measurement and is thus well suited for detecting the
faint lensing induced and gravity-wave induced B modes. In mosaicking
observation, compared to the single dish, the interferometer is in general more
efficient in separating E and B modes, and for high signal-to-noise per pixel
it needs about three times fewer pixels to measure extremely blue polarization
power spectra.


title: Quasar Hosts and the Black Hole-Spheroid Connection

abstract:
  I review our current understanding of the structures and ages of the host
galaxies of quasars, and the masses of their central black holes. At low
redshift, due largely to the impact of the Hubble Space Telescope, there is now
compelling evidence that the hosts of quasars with M_V < -24 mag are virtually
all massive ellipticals, with basic properties indistinguishable from those
displayed by their quiescent counterparts. The masses of these spheroids are as
expected given the relationship between black hole and spheroid mass now
established for nearby galaxies, as is the growing prevalence of significant
disk components in the hosts of progressively fainter active nuclei. In fact,
from spectroscopic measurements of the velocity of the broad-line region in
quasars, it has now proved possible to obtain an independent dynamical estimate
of the masses of the black holes that power quasars. I summarize recent results
from this work, which can be used to demonstrate that the black hole-spheroid
mass ratio in quasars is the same as that found for quiescent galaxies, namely
M_bh = 0.0012 M_sph. These results offer the exciting prospect of using
observations of quasars and their hosts to extend the study of the black
hole-spheroid mass ratio out to very high redshifts (z > 2). Moreover, there is
now good evidence that certain ultraviolet quasar emission lines can provide
robust estimates of black hole masses from the observed optical spectra of
quasars out to z > 2, and perhaps even at z > 4. By combining such information
with deep, high-resolution infrared imaging of high-redshift quasar hosts on
8-m class telescopes, there is now a real prospect of clarifying the evolution
of the black hole spheroid connection over cosmological time scales.


title:
Optical Limits on Precursor Emission from Gamma-Ray Bursts with Known
  Redshift

abstract:
  Making use of virtual observatory data, we present the first comprehensive
sample of optical observations conducted before the explosion times of all
gamma-ray bursts (GRBs) with known redshifts. In total, the fields of 11 such
GRBs were observed by the Near-Earth Asteroid Tracking (NEAT) program from
years to hours before the bursts. Though the typical limiting magnitudes from
these observations are R~20 mag, we find no evidence for a significant
detection of a precursor. The deepest non-detection of precursor emission is
from GRB 030329, reaching down to an absolute B-band magnitude of M_B -18 mag
from 6--1500 days (restframe) before the burst. This is of comparable
brightness to supernovae, which, in some scenarios for GRB progenitors, are
predicted to pre-date a GRB on similar timescales. Since sources cannot be
localized to better than ~500 milliarcsecond (3 sigma) with current large-area
surveys, unrelated supernovae or AGN activity in GRB hosts could be mistaken
for genuine precursor emission. This possibility motivates the need for not
only deep wide-field imaging, but imaging at high spatial resolution.


title:
Further Evidence for Chemical Fractionation from Ultraviolet
  Observations of Carbon Monoxide

abstract:
  Ultraviolet absorption from interstellar 12CO and 13CO was detected toward
rho Oph A and chi Oph. The measurements were obtained at medium resolution with
the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Column
density ratios, N(12CO)/N(13CO), of 125 \pm 23 and 117 \pm 35 were derived for
the sight lines toward rho Oph A and chi Oph, respectively. A value of 1100 \pm
600 for the ratio N(12C16O)/N(12C18O) toward rho Oph A was also obtained.
Absorption from vibrationally excited H_2 (v" = 3) was clearly seen toward this
star as well.
  The ratios are larger than the isotopic ratios for carbon and oxygen
appropriate for ambient interstellar material. Since for both carbon and oxygen
the more abundant isotopomer is enhanced, selective isotopic photodissociation
plays the key role in the fractionation process for these directions. The
enhancement arises because the more abundant isotopomer has lines that are more
optically thick, resulting in more self shielding from dissociating radiation.
A simple argument involving the amount of self shielding [from N(12CO)] and the
strength of the ultraviolet radiation field premeating the gas (from the amount
of vibrationally excited H_2) shows that selective isotopic photodissociation
controls the fractionation seen in these two sight lines, as well as the sight
line to zeta Oph.


title: Optical and NIR Observations of the Afterglow of GRB 020813

abstract:
  We present optical and near-infrared (NIR) photometry of the bright afterglow
of GRB 020813. Our data span from 3 hours to 4 days after the GRB event. A
rather sharp achromatic break is present in the light curve, 14 hours after the
trigger. In the framework of jetted fireballs, this break corresponds to a jet
half opening angle of (1.9 +- 0.2) deg, the smallest value ever inferred for a
GRB. We discuss our results in the framework of currently available models, and
find that they have problems in explaining the joint temporal and spectral
properties, and in particular the slow decay before the break.


title:
Bipolar Supernova Explosions: Nucleosynthesis & Implication on
  Abundances in Extremely Metal-Poor Stars

abstract:
  Hydrodynamics and explosive nucleosynthesis in bipolar supernova explosions
are examined to account for some peculiar properties of hypernovae as well as
peculiar abundance patterns of metal-poor stars. The explosion is supposed to
be driven by bipolar jets which are powered by accretion onto a central
remnant. We explore the features of the explosions with varying progenitors'
masses and jet properties. The outcomes are different from conventional
spherical models. (1) In the bipolar models, Fe-rich materials are ejected at
high velocities along the jet axis, while O-rich materials occupy the central
region whose density becomes very high as a consequence of continuous accretion
from the side. This configuration can explain some peculiar features in the
light curves and the nebular spectra of hypernovae. (2) Production of $^{56}$Ni
tends to be smaller than in spherical thermal bomb models. To account for a
large amount of $^{56}$Ni observed in hypernovae, the jets should be initiated
when the compact remnant mass is still smaller than $2-3\msun$, or the jets
should be very massive and slow. (3) Ejected isotopes are distributed as
follows in order of decreasing velocities: $^{64}$Zn, $^{59}$Co, $^{56}$Fe,
$^{44}$Ti, and $^{4}$He at the highest velocities, $^{55}$Mn, $^{52}$Cr,
$^{32}$S, and $^{28}$Si at the intermediate velocities, and $^{24}$Mg, $^{16}$O
at the lowest velocities. (4) The abundance ratios (Zn, Co)/Fe are enhanced
while the ratios (Mn, Cr)/Fe are suppressed. This can account for the abundance
pattern of extremely metal-poor stars. These agreements between the models and
observations suggest that hypernovae are driven by bipolar jets and have
significantly contributed to the early Galactic chemical evolution.


title:
Spectroscopic Discovery of the Supernova 2003dh Associated with GRB
  030329

abstract:
  We present early observations of the afterglow of the Gamma-Ray Burst (GRB)
030329 and the spectroscopic discovery of its associated supernova SN 2003dh.
We obtained spectra of the afterglow of GRB 030329 each night from March 30.12
(0.6 days after the burst) to April 8.13 (UT) (9.6 days after the burst). The
spectra cover a wavelength range of 350 nm to 850 nm. The early spectra consist
of a power-law continuum (F_nu ~ nu^{-0.9}) with narrow emission lines
originating from HII regions in the host galaxy, indicating a low redshift of
z=0.1687. However, our spectra taken after 2003 Apr. 5 show broad peaks in flux
characteristic of a supernova. Correcting for the afterglow emission, we find
the spectrum of the supernova is remarkably similar to the type Ic `hypernova'
SN 1998bw. While the presence of supernovae have been inferred from the light
curves and colors of GRB afterglows in the past, this is the first direct,
spectroscopic confirmation that a subset of classical gamma-ray bursts
originate from supernovae.


title:
The First Substellar Subdwarf? Discovery of a Metal-poor L Dwarf with
  Halo Kinematics

abstract:
  We present the discovery of the first L-type subdwarf, 2MASS
J05325346+8246465. This object exhibits enhanced collision-induced H$_2$
absorption, resulting in blue NIR colors ($J-K_s = 0.26{\pm}0.16$). In
addition, strong hydride bands in the red optical and NIR, weak TiO absorption,
and an optical/J-band spectral morphology similar to the L7 DENIS 0205$-$1159AB
imply a cool, metal-deficient atmosphere. We find that 2MASS 0532+8246 has both
a high proper motion, $\mu$ = 2$\farcs60\pm0\farcs$15 yr$^{-1}$, and a
substantial radial velocity, $v_{rad} = -195{\pm}11$ km s$^{-1}$, and its
probable proximity to the Sun (d = 10--30 pc) is consistent with halo
membership. Comparison to subsolar-metallicity evolutionary models strongly
suggests that 2MASS 0532+8246 is substellar, with a mass of 0.077 $\lesssim$ M
$\lesssim$ 0.085 M$_{\sun}$ for ages 10--15 Gyr and metallicities $Z =
0.1-0.01$ $Z_{\sun}$. The discovery of this object clearly indicates that star
formation occurred below the Hydrogen burning mass limit at early times,
consistent with prior results indicating a flat or slightly rising mass
function for the lowest-mass stellar subdwarfs. Furthermore, 2MASS 0532+8246
serves as a prototype for a new spectral class of subdwarfs, additional
examples of which could be found in NIR proper motion surveys.


title:
Correlated adiabatic and isocurvature CMB fluctuations in the wake of
  the WMAP

abstract:
  In general correlated models, in addition to the usual adiabatic component
with a spectral index n_ad1 there is another adiabatic component with a
spectral index n_ad2 generated by entropy perturbation during inflation. We
extend the analysis of a correlated mixture of adiabatic and isocurvature CMB
fluctuations of the WMAP group, who set the two adiabatic spectral indices
equal. Allowing n_ad1 and n_ad2 to vary independently we find that the WMAP
data favor models where the two adiabatic components have opposite spectral
tilts. Using the WMAP data only, the 2-sigma upper bound for the isocurvature
fraction f_iso of the initial power spectrum at k_0=0.05 Mpc^{-1} increases
somewhat, e.g., from 0.76 of n_ad2 = n_ad1 models to 0.84 with a prior n_iso <
1.84 for the isocurvature spectral index. We also comment on a possible
degeneration between the correlation component and the optical depth tau.
Moreover, the measured low quadrupole in the TT angular power could be achieved
by a strong negative correlation, but then one needs a large tau to fit the TE
spectrum.


title:
Shocks and Particle Acceleration in Supernova Remnants: Observational
  Features

abstract:
  The last ten years a number of observational advances have substantially
increased our knowledge of shock phenomena in supernova remnants. This progress
has mainly been made possible by the recent improvements in X-ray and Gamma-ray
instrumentation. It has become clear that some shell-type supernova remnants,
e.g. SN 1006, have X-ray emission dominated by synchrotron radiation, proving
that electrons are accelerated up to 100 TeV. This is still an order of
magnitude below 3E15 eV, at which energy the ion cosmic ray spectrum at earth
shows a spectral break. So one of the major goals is to prove that supernova
remnants are capable of accelerating ions at least up that energy.
  Here I review the evidence that ions and electrons are accelerated up to
energies ~100 TeV in supernova remnants, and, in addition, the recent progress
that has been made in understanding the physics of collisionless shock fronts
and the magnetic fields inside supernova remnants.


title: Tracing the large scale structure in the Chandra Deep Field South

abstract:
  We report the discovery of large scale structures of X-ray sources in the
1Msec observation of the Chandra Deep Field South. Two main structures appear
as narrow (Delta_z < 0.02) spikes in the source redshift distribution at z=0.67
and z=0.73, respectively. Their angular distribution spans a region at least ~
17 arcmin wide, corresponding to a physical size of 7.3 h_{70}^{-1} Mpc at a
redshift of z ~ 0.7 (Omega_m=0.3, Omega_{Lambda}=0.7). These spikes are
populated by 19 sources each, which are mainly identified as Active Galactic
Nuclei (AGN). Two sources in each spike are extended in X-rays, corresponding
to galaxy groups/clusters embedded in larger structures. The X-ray source
redshift distribution shows other spikes, the most remarkable at z=1.04, 1.62
and 2.57. This is one of the first evidences for large scale structure traced
by X-ray sources and for spatial clustering of X-ray selected AGN. The X-ray
data have been complemented with the spectroscopic data from the K20 near
infrared survey (Cimatti et al. 2002), which covers ~1/10 of the X-ray field.
Also in this survey the source redshift distribution shows several spikes. Two
narrow structures at z=0.67 and z=0.73 (again with Delta_z ~ 0.02) are the most
significant features, containing 24 and 47 galaxies, respectively. While the
K20 structure at z=0.73 is dominated by a standard galaxy cluster with a
significant concentration around a central cD galaxy and morphological
segregation, the galaxies at z=0.67 constitute a loose structure rather
uniformly distributed along the K20 field.[abridged]


title: 2-point anisotropies in WMAP and the Cosmic Quadrupole

abstract:
  Large-scale modes in the temperature anisotropy power spectrum C_l measured
by the Wilkinson Microwave Anisotropy Probe (WMAP), seem to have lower
amplitudes (C_2, C_3 and C_4) than that expected in the so called concordance
LCDM model. In particular, the quadrupole C_2 is reported to have a smaller
value than allowed by cosmic variance. This has been interpreted as a possible
indication of new physics. In this paper we re-analyse the WMAP data using the
2-point angular correlation and its higher-order moments. This method, which
requires a full covariance analysis, is more direct and provides better
sampling of the largest modes than the standard harmonic decomposition. We show
that the WMAP data is in good agreement (~ 30% probability) with a LCDM model
when the WMAP data is considered as a particular realization drawn from a set
of realistic LCDM simulations with the corresponding covariance. This is also
true for the higher-order moments, shown here up to 6th order, which are
consistent with the Gaussian hypothesis. The sky mask plays a major role in
assessing the significance of these agreements. We recover the best fit model
for the low-order multipoles based on the 2-point correlation with different
assumptions for the covariance. Assuming that the observations are a fair
sample of the true model, we find C_2 = 123 +/- 233, C_3= 217 +/- 241 and C_4 =
212 +/- 162 (in mu K^2). The errors increase by about a factor of 5 if we
assume the \lcdm model. If we exclude the Galactic plane |b|<30 from our
analysis, we recover very similar values within the errors (ie C_2=172, C_3=
89, C_4=129). This indicates that the Galactic plane is not responsible for the
lack of large-scale power in the WMAP data.


title: Detection of OH absorption against PSR B1849+00

abstract:
  We have searched for OH absorption against seven pulsars using the Arecibo
telescope. In both OH mainlines (at 1665 and 1667 MHz), deep and narrow
absorption features were detected toward PSR B1849+00. In addition, we have
detected several absorption and emission features against B33.6+0.1, a nearby
supernova remnant (SNR). The most interesting result of this study is that a
pencil-sharp absorption sample against the PSR differs greatly from the
large-angle absorption sample observed against the SNR. If both the PSR and the
SNR probe the same molecular cloud then this finding has important implications
for absorption studies of the molecular medium, as it shows that the statistics
of absorbing OH depends on the size of the background source. We also show that
the OH absorption against the PSR most likely originates from a small (<30
arcsec) and dense (>10^5 cm^-3) molecular clump.


title: Physics with Cosmic Neutrinos, PeV to ZeV

abstract:
  We begin with a brief overview of highest-energy cosmic ray data, and the
experiments which will perform neutrino astronomy. We then discuss two particle
physics aspects of neutrinos. They are possible long-lifetime decay of the
neutrino, and a measurement of the neutrino-nucleon cross-section at a CMS
energy orders of magnitude beyond what can be achieved with terrestrial
accelerators. Measurement of an anomalously large neutrino cross-section would
indicate new physics (e.g. low string-scale, extra dimensions, precocious
unification), while a smaller than expected cross-section would reveal an
aspect of QCD evolution. We then discuss aspects of neutrino-primary models for
the extreme-energy (EE) cosmic ray data. Primary neutrinos in extant data are
motivated by the directional clustering at EE reported by the AGASA experiment.
We discuss the impact of the strongly-interacting neutrino hypothesis on
lower-energy physics via dispersion relations, the statistical significance of
AGASA directional clustering, and the possible relevance of the Z-burst
mechanism for existing EE cosmic ray data.


title: Methanol and H2o Masers in a Disk Around GL2789

abstract:
  VLBA and EVN radio observations of H2O masers at 22 GHz and methanol masers
at 6.7 GHz have been used to obtain images of the maser spots in the infrared
object GL2789, which is associated with the young stellar object V645Cyg. The
position of these masers coincides with that of the optical object to within
0.2 arcsec. The maser spots are located in a line oriented north--south, and
their positions and radial velocities can be described by a model with a
Keplerian disk with maximum radius 40 AU for the H2O masers and 800 AU for the
methanol masers. The H2O and methanol masers spots are unresolved, and the
lower limits for their brightness temperatures are 2x10^{13} K and 1.4x10^9 K,
respectively. A model in which the maser radiation is formed in extended
water-methanol clouds associated with ice planets forming around the young star
is proposed.


title:
A differential study of the oxygen abundances in the Galactic thin and
  thick disks

abstract:
  First results from a study into the abundance trends of oxygen in the
Galactic thin and thick disks are presented. Oxygen abundances for 63 nearby F
and G dwarf stars, based on very high resolution spectra ($R\sim215 000$) and
high signal-to-noise ($S/N>400$) of the faint forbidden oxygen line at 6300
{\AA}, have been determined. Our findings can be summarized as follows: {\bf
1)} at $\rm [Fe/H]<0$ the oxygen trends in the thin and thick disk are smooth
and distinct, indicating their different origins, {\bf 2)} $\rm [O/Fe]$ for the
thick disk stars show a turn-over at [Fe/H]$\sim -0.35$, indicating the peak of
the enrichment from SNe type Ia to the interstellar medium, {\bf 3)} the thin
disk stars show a shallow decrease going from $\rm [Fe/H] \sim -0.7$ to the
highest metallicities with no apparent turn-over present indicating a more
quiet star formation history, and {\bf 4)} $\rm [O/Fe]$ continues to decrease
at $\rm [Fe/H]>0$ without showing the leveling out that previously has been
seen.


title: Dark Matter and Dark Energy: Summary and Future Directions

abstract:
  This paper reviews the progress reported at this Royal Society Discussion
Meeting and advertizes some possible future directions in our drive to
understand dark matter and dark energy. Additionally, a first attempt is made
to place in context the exciting new results from the WMAP satellite, which
were published shortly after this Meeting. In the first part of this review,
pieces of observational evidence shown here that bear on the amounts of dark
matter and dark energy are reviewed. Subsequently, particle candidates for dark
matter are mentioned, and detection strategies are discussed. Finally, ideas
are presented for calculating the amounts of dark matter and dark energy, and
possibly relating them to laboratory data.


title: Circumstellar Disks in pre-Main Sequence Stars

abstract:
  This review covers the properties of disks around pre-main--sequence stars.
It is at this time in the evolution that planets form, and it is important to
understand the properties of these disks to understand planet formation. I
discuss disk shapes, masses and temperatures, the properties of the host stars,
disk lifetimes and dissipation processes. Finally, evidence of grain growth
during pre-main-sequence evolution is briefly summarized.