title: Plasmoid-Induced-Reconnection and Fractal Reconnection

abstract:
  As a key to undertanding the basic mechanism for fast reconnection in solar
flares, plasmoid-induced-reconnection and fractal reconnection are proposed and
examined. We first briefly summarize recent solar observations that give us
hints on the role of plasmoid (flux rope) ejections in flare energy release. We
then discuss the plasmoid-induced-reconnection model, which is an extention of
the classical two-ribbon-flare model which we refer to as the CSHKP model. An
essential ingredient of the new model is the formation and ejection of a
plasmoid which play an essential role in the storage of magnetic energy (by
inhibiting reconnection) and the induction of a strong inflow into reconnection
region. Using a simple analytical model, we show that the plasmoid ejection and
acceleration are closely coupled with the reconnection process, leading to a
nonlinear instability for the whole dynamics that determines the macroscopic
reconnection rate uniquely. Next we show that the current sheet tends to have a
fractal structure via the following process path: tearing, sheet thinning,
Sweet- Parker sheet, secondary tearing, further sheet thinning... These
processes occur repeatedly at smaller scales until a microscopic plasma scale
(either the ion Larmor radius or the ion inertial length) is reached where
anomalous resistivity or collisionless reconnection can occur. The current
sheet eventually has a fractal structure with many plasmoids (magnetic islands)
of different sizes. When these plasmoids are ejected out of the current sheets,
fast reconnection occurs at various different scales in a highly time dependent
manner. Finally, a scenario is presented for fast reconnection in the solar
corona on the basis of above plasmoid-induced-reconnection in a fractal current
sheet.


title: Cosmological Perturbation Theory and Structure Formation

abstract:
  These lecture notes discuss several topics in the physics of cosmic structure
formation starting from the evolution of small-amplitude fluctuations in the
radiation-dominated era. The topics include relativistic cosmological
perturbation theory with the scalar-vector-tensor decomposition, the evolution
of adiabatic and isentropic initial fluctuations, microwave background
anisotropy, spatial and angular power spectra, the cold dark matter linear
transfer function, Press-Schechter theory, and a brief introduction to
numerical simulation methods.


title:
Jet- and Wind-Driven Ionized Outflows in the Superbubble and
  Star-Forming Disk of NGC 3079

abstract:
  HST WFPC2 images are presented that span the inner 19 kpc diameter of the
edge-on spiral galaxy NGC 3079; they are combined with ground-based Halpha+[N
II] Fabry-Perot spectra and VLA images of radio polarization vectors and
rotation measures. Ionized gas filaments within 9 kpc diameter project ~3 kpc
above the disk, with the brightest forming the 1 kpc diameter superbubble. They
are often resolved into strands ~0."3 (25 pc) wide which emerge from the
nuclear CO ring as five distinct gas streams with velocity gradients and
dispersions of hundreds of km/s. One stream flows for 250 pc and aligns with
the VLBI-scale radio jet, the other four are not connected to the jet, instead
curving to the vertical 0.6 kpc above the galaxy disk, then dispersing in a
spray of droplets each with ionized mass ~1000 sqrt(f) Msun (volume filling
factor f > 0.003 from our data). Shredded clumps of disk gas form a similar
structure in hydro models of a galaxy-scale wind. The pattern of magnetic
fields and the gas kinematics also suggest a wind of mechanical luminosity
10^43 erg/s that has stagnated in the galaxy disk at radius ~800 pc, flared to
larger radii with increasing height as the balancing ISM pressure reduces above
the disk, and entrained dense clouds into a vortex. Total KE and momentum of
the filaments are (0.4-5)x10^55 sqrt(f) ergs and (1.6-6)x10^47 sqrt(f) dyne s.
A star-forming complex elsewhere in the galaxy shows a striking spray of linear
filaments that extend for hundreds of parsecs.


title: The birth of strange stars and their dynamo-originated magnetic fields

abstract:
  It is shown that protostrange stars (PSSs) can be convective and that there
are two possible scenarios describing their turbulence. Besides the local
turbulence on the scale which is less than the mean free path of neutrinos,
large-scale (~1 km) convection also may occur with properties that are similar
to those of convection in protoneutron stars (PNSs). We thus suggest that
strange stars can also create dynamo-originated magnetic fields during the
deleptonization episode soon after a supernova explosion. Further detailed
investigations are needed to see whether or not strange stars and neutron stars
can be distinguished according to the differences in dynamo actions in strange
quark matter and in neutron matter. The magnetic fields of strange stars and
neutron stars may also behave very differently during the accretion-phase when
the fields decay.


title: A Further Study of Relative longitude shift of Pulsar Beams

abstract:
  It is of great important to study pulsar beam shapes if we are concerned with
emission theories and pulsar birth rate. Both observations and/or the inverse
Compton scattering model show that different emission components are emitted
from different heights. The relative longitude phase shifts due to different
heights of emission components and to the toroidal velocity of electron are
considered in this paper. Several possible observational features arising from
the phase shift effects are presented. The emission beams may not have circular
cross sections although the emission regions may be symmetric with respect to
the magnetic axes.


title: The fastest rotating pulsar: A strange star?

abstract:
  According to the observational limits on the radius and mass, the fastest
rotating pulsar (PSR 1937+21) is probably a strange star, or at least some
neutron star equations of state should be ruled out, if we suggest that a
dipole magnetic field is relevant to its radio emission. We presume that the
millisecond pulsar is a strange star with {\em much} low mass, small radius,
and weak magnetic moment.


title: Attractors and Isocurvature Perturbations in Quintessence Models

abstract:
  We investigate the evolution of cosmological perturbations in scenarios with
a quintessence scalar field, both analytically and numerically. In the tracking
regime for quintessence, we find the long wavelength solutions for
quintessential perturbations. We discuss the possibility of isocurvature modes
generated by the quintessence sector and their impact on observations.


title: Adaptive optics at the WHT

abstract:
  The WHT is unusually well-placed for exploitation of adaptive-optics (AO)
technology. The site seeing is excellent (median 0.7 arcsec), dome seeing is
negligible, and preliminary studies indicate that most of the atmospheric
seeing originates in a well-defined layer at low altitude, which bodes well for
future laser-guide-star AO. The Durham group have built up extensive experience
with natural-guide-star adaptive-optics experiments at the GHRIL Nasmyth focus,
and the NAOMI common-user AO facility is due to be commissioned at this focus
early in 2000. NAOMI will provide near-diffraction-limited imaging in the IR
(Strehl ~ 0.6, FWHM ~ 0.15 arcsec in K) and is expected to give significant
correction in the optical (poorer Strehl, but similar FWHM). NAOMI will perform
better at short wavelengths than AO systems on other telescopes, and observers
will require instrumentation that can exploit this crucial advantage.


title: Scalar field models for an accelerating universe

abstract:
  I describe a new class of quintessence+CDM models in which late time scalar
field oscillations can give rise to both quintessence and cold dark matter.
Additionally, a versatile ansatz for the luminosity distance is used to
reconstruct the quintessence equation of state in a model independent manner
from observations of high redshift supernovae.


title:
Relativistic Outflows from Advection-Dominated Accretion Disks around
  Black Holes

abstract:
  The Newtonian ADAF model has been generalized recently to obtain the ADIOS
model that includes outflows of energy and angular momentum. The utilization of
a Newtonian gravitational potential limits the ability of the ADIOS model to
describe the inner region of the disk, where any relativistic outflows are
likely to originate. In this paper we modify the ADIOS scenario to incorporate
a pseudo-Newtonian potential, which approximates the effects of general
relativity. The analysis yields a unique, self-similar solution for the
structure of the coupled disk/wind system. Interesting features of the new
solution include the relativistic character of the outflow in the vicinity of
the radius of marginal stability, which may help to explain the formation of
relativistic jets in active galaxies. The unique density variation obtained
agrees with that implied by the dependence of the X-ray hard time lags on the
Fourier frequency for a number of accreting galactic black hole candidates.


title: Science Prospects for SPI

abstract:
  After the recent beautiful results on gamma-ray lines obtained with CGRO, the
INTEGRAL mission with the imaging-spectrometer SPI will set the next milestone,
combining improved sensitivity and angular resolution with a considerable
increase in spectral resolution. SPI is expected to provide significant new
information on galactic nucleosynthesis processes and star formation activity,
as traced by the distributions of annihilation radiation and radioactive
isotopes such as 26Al and 60Fe. The unprecedented spectral resolution will
allow the study of dynamic processes in stellar mass ejections and will provide
access to kinematic distance estimates for gamma-ray line sources. The study of
supernovae and their remnants will be prime objectives for SPI observations.
Nearby type Ia SN, within 15 Mpc or so, are in reach of the instrument and a
few such events are expected during the lifetime of INTEGRAL. Young galactic
supernova remnants, possibly hidden by interstellar dust, may be unveiled by
their characteristic gamma-ray line signature from the radioactive decay of
44Ti, as has been demonstrated by COMPTEL for Cas A and possibly RX
J0852.0-4622. Classical novae are also among the SPI targets, which may observe
the gamma-ray lines from radioactive 7Be and 22Na. Such observations can
constrain the physics of the nova explosions and will allow to evaluate their
role as nucleosynthesis sites. The interaction of cosmic rays with the dense
matter in molecular clouds may be another source of gamma-ray lines that is
potentially accessible to SPI. Finally after the SIGMA results on Nova Muscae
and 1E1740.7-2942, and a possible 2.223 MeV line detection by COMPTEL, the
search for lines from X novae is another way to participate in the
understanding of the physical conditions in these close binary systems.


title: Chandra Observations of the Gravitationally Lensed System 2016+112

abstract:
  An observation of the gravitationally lensed system 2016+112 with the Chandra
X-ray Observatory has resolved a mystery regarding the proposed presence of a
dark matter object in the lens plane of this system. The Chandra ACIS
observation has clearly detected the lensed images of 2016+112 with positions
in good agreement with those reported in the optical and also detects 13
additional X-ray sources within a radius of 3.5 arcmin. Previous X-ray
observations in the direction of 2016+112 with the ROSAT HRI and ASCA SIS have
interpreted the X-ray data as arising from extended emission from a dark
cluster. However, the present Chandra observation can account for all the X-ray
emission as originating from the lensed images and additional point X-ray
sources in the field. Thus cluster parameters based on previous X-ray
observations are unreliable. We estimate an upper limit on the mass-to-light
ratio within a radius of 800 h_(50)^(-1) kpc of M/L_(V) < 190 h_(50)
(M/L_(V))_Sun. The lensed object is quite unusual, with reported narrow
emission lines in the optical that suggest it may be a type-2 quasar (Yamada
et. al. 1999). Our modeling of the X-ray spectrum of the lensed object implies
that the column density of an intrinsic absorber must lie between 3 and 85 x
10^22 cm^-2 (3 sigma confidence level). The 2-10 keV luminosity of the lensed
object, corrected for the lens magnification effect and using the above range
of intrinsic absorption, is 3 x 10^43 - 1.4 x 10^44 erg/s.


title:
Exact Expressions for the Critical Mach Numbers in the Two-Fluid Model
  of Cosmic-Ray Modified Shocks

abstract:
  The acceleration of relativistic particles due to repeated scattering across
a shock wave remains the most attractive model for the production of energetic
cosmic rays. This process has been analyzed extensively during the past two
decades using the ``two-fluid'' model of diffusive shock acceleration. It is
well known that 1, 2, or 3 distinct solutions for the flow structure can be
found depending on the upstream parameters. The precise nature of the critical
conditions delineating the number and character of shock transitions has
remained unclear, mainly due to the inappropriate choice of parameters used in
the determination of the upstream boundary conditions. We derive the exact
critical conditions by reformulating the upstream boundary conditions in terms
of two individual Mach numbers defined with respect to the cosmic-ray and gas
sound speeds, respectively. The gas and cosmic-ray adiabatic indices are
assumed to remain constant throughout the flow, although they may have
arbitrary, independent values. Our results provide for the first time a
complete, analytical classification of the parameter space of shock transitions
in the two-fluid model. When multiple solutions are possible, we propose using
the associated entropy distributions as a means for indentifying the most
stable configuration.


title: A New Very Cool White Dwarf Discovered by the Sloan Digital Sky Survey

abstract:
  Early data taken during commissioning of the SDSS have resulted in the
discovery of a very cool white dwarf. It appears to have stronger collision
induced absorption from molecular hydrogen than any other known white dwarf,
suggesting it has a cooler temperature than any other. While its distance is
presently unknown, it has a surprisingly small proper motion, making it
unlikely to be a halo star. An analysis of white dwarf cooling times suggests
that this object may be a low-mass star with a helium core. The SDSS imaging
and spectroscopy also recovered LHS 3250, the coolest previously known white
dwarf, indicating that the SDSS will be an effective tool for identifying these
extreme objects.


title: Possible Strong Gravitational Wave Sources for the LISA Antenna

abstract:
  Recently Fuller & Shi proposed that the gravitational collapse of
supermassive objects ($M \gtrsim 10^4M_\odot$) could be a cosmological source
of $\gamma$-ray bursts (GRBs). The major advantage of their model is that
supermassive object collapses are far more energetic than solar mass-scale
compact mergers. Also, in their proposal the seeds of supermassive black holes
(SMBHs) thus formed could give rise to the SMBHs observed at the center of many
galaxies. We argue here that, besides the generation of GRBs, there could well
occur a strong generation of gravitational waves (GWs) during the formation of
SMBHs. As a result, the rate of such GW bursts could be as high as the rate of
GRBs in the model by Fuller & Shi. In this case, the detection of GRBs and
bursts of GWs should occur with a small time difference. We also argue that the
GWs produced by the SMBHs studied here could be detected when the Laser
Interferometric Space Antenna (LISA) becomes operative.


title: Evidence for Extinction and Accretion Variability in T Tau S

abstract:
  We present angularly resolved spectra of T Tau North and South in the 3
micron water ice feature and K-band. Most of the water ice absorption lies
along the line of sight toward T Tau South, confirming that it is viewed
through stronger extinction. A decrease in ice-band absorption toward T Tau S
between December 1998 and January 2000, significant at the 2 sigma level, was
associated with an increase in its near infrared flux. Br gamma emission is
detected in T Tau North and South and H_{2} (2.12 micron) emission only toward
T Tau South, consistent with previous studies of infrared companions to T Tauri
stars. Our results suggest that the near IR variability of T Tau S is probably
caused by both variations in accretion rate and variable extinction along the
line of sight.


title: Theory of Extrasolar Giant Planet Transits

abstract:
  We present a synthesis of physical effects influencing the observed
lightcurve of an extrasolar giant planet (EGP) transiting its host star. The
synthesis includes a treatment of Rayleigh scattering, cloud scattering,
refraction, and molecular absorption of starlight in the EGP atmosphere. Of
these effects, molecular absorption dominates in determining the
transit-derived radius $R$. Using a generic model for the atmosphere of EGP
HD209458b, we perform a fit to the best available transit lightcurve data, and
infer that this planet has a radius at a pressure of 1 bar, $R_1$, equal to
94430 km. We predict that $R$ will be a function of wavelength of observation,
with a robust prediction of variations of $\pm 1$% at infrared wavelengths
where H$_2$O opacity in the high EGP atmosphere dominates.


title:
Spatial/Spectral Resolution of a Galactic Bulge K3 Giant Stellar
  Atmosphere via Gravitational Microlensing

abstract:
  We present two Keck HIRES spectra (R=40,000) of a bulge K3 giant taken on
successive nights during the second caustic crossing of the binary microlensing
event EROS BLG-2000-5. This caustic crossing served to effectively resolve the
surface of the source star: the spectrum from the second night is dominated by
the limb, while the spectrum from the first night is comprised of light from a
broader range of radii. To demonstrate that the spectra are adequate to resolve
the differences between them, we analyze the H-alpha line. The equivalent width
is ~8% smaller on the second night, and the signal-to-noise ratio per
resolution element (165 and 75 on the two nights respectively) is sufficient to
show that the difference is approximately constant over the ~2A (~15 resolution
element) extent of the line. The sign of the difference is in the expected
direction since the limb is the coolest part of the star and therefore should
have the weakest H-alpha. We invite atmosphere modelers to predict the
difference spectrum from the entire spectral range 5500<lambda<7900A so that
these predictions can be compared to our observations.


title:
The early X-ray emission from V382 Velorum (=Nova Vel 1999): An internal
  shock model

abstract:
  We present the results of ASCA and RXTE observations of the early X-ray
emission from the classical nova V382 Velorum. Its ASCA spectrum was hard
(kT~10 keV) with a strong (10**23 cm**-2) intrinsic absorption. In the
subsequent RXTE data, the spectra became softer both due to a declining
temperature and a diminishing column. We argue that this places the X-ray
emission interior to the outermost ejecta produced by V382 Vel in 1999, and
therefore must have been the result of a shock internal to the nova ejecta. The
weakness of the Fe K alpha lines probably indicates that the X-ray emitting
plasmas are not in ionization equilibrium.


title:
Oscillator Strengths for B-X, C-X, and E-X Transitions in Carbon
  Monoxide

abstract:
  Band oscillator strengths for electronic transitions in CO were obtained at
the Synchrotron Radiation Center of the University of Wisconsin-Madison. Our
focus was on transitions that are observed in interstellar spectra with the Far
Ultraviolet Spectroscopic Explorer; these transitions are also important in
studies of selective isotope photodissociation where fractionation among
isotopomers can occur. Absorption from the ground state (X ^1Sigma^+ v'' = 0)
to A ^1Pi (v'= 5), B ^1Sigma^+ (v' = 0, 1), C ^1Sigma^+ (v' = 0, 1), and E ^1Pi
(v' = 0) was measured. Fits to the A - X (5, 0) band, whose oscillator strength
is well known, yielded the necessary column density and excitation temperature.
These parameters were used in a least-squares fit of the observed profiles for
the transitions of interest to extract their band oscillator strengths. Our
oscillator strengths are in excellent agreement with results from recent
experiments using a variety of techniques. This agreement provides the basis
for a self-consistent set of f-values at far ultraviolet wavelengths for
studies of interstellar (and stellar) CO.


title: A massive reservoir of low-excitation molecular gas at high redshift

abstract:
  Molecular hydrogen is an important component of galaxies because it fuels
star formation and accretion onto AGN, the two processes that generate the
large infrared luminosities of gas-rich galaxies. Observations of spectral-line
emission from the tracer molecule CO are used to probe the properties of this
gas. But the lines that have been studied in the local Universe, mostly the
lower rotational transitions of J = 1-0 and J = 2-1, have hitherto been
unobservable in high-redshift galaxies. Instead, higher transitions have been
used, although the densities and temperatures required to excite these higher
transitions may not be reached by much of the gas. As a result, past
observations may have underestimated the total amount of molecular gas by a
substantial amount. Here we report the discovery of large amounts of
low-excitation molecular gas around the infrared-luminous quasar, APM
08279+5255 at z = 3.91, using the two lowest excitation lines of 12CO (J = 1-0
and J = 2-1). The maps confirm the presence of hot and dense gas near the
nucleus, and reveal an extended reservoir of molecular gas with low excitation
that is 10 to 100 times more massive than the gas traced by higher-excitation
observations. This raises the possibility that significant amounts of
low-excitation molecular gas may lurk in the environments of high-redshift (z >
3) galaxies.


title:
Galactic Chemical Abundances at z>3 I: First Results from the Echellette
  Spectrograph and Imager

abstract:
  We present the first results from an ongoing survey to discover and measure
the metallicity of z>3 damped Lya systems with the Echellette Spectrograph and
Imager (ESI) on the Keck II telescope. Our motivation arises from a recent
study on the damped Lya systems suggesting only mild evolution in the cosmic
metallicity from z~2 to 4. The Echellette Spectrograph and Imager, which
provides two complementary spectroscopic modes, is the ideal instrument for a
z>3 damped Lya survey. We describe our observing strategy and report on the
discovery and analysis of 5 new z>3 damped Lya systems acquired in a single
night of observing. These observations further support the principal
conclusions of the previous study: (1) the cosmic metallicity in neutral gas
inferred from the damped Lya systems does not evolve significantly from z~2 to
4; (2) the unweighted metallicity exhibits a statistically significant decrease
with increasing redshift; and (3) not a single damped Lya system has a
metallicity below [Fe/H]=-3. We discuss the implications of these results and
comment on recent theoretical studies which attempt to explain the
observations.


title: How to focus a Cherenkov telescope

abstract:
  Cherenkov telescopes image the Cherenkov emission from air showers. A priori,
it is not obvious if the `best' images are achieved by measuring Cherenkov
photon angles, i.e. focusing the telescope at infinity, or by considering the
air shower as an object to be imaged, in which case one might focus the
telescope on the central region of the shower. The issue is addressed using
shower simulations.


title: Evolution of Isolated Neutron Stars

abstract:
  In this paper we briefly review our recent results on evolution and
properties of isolated neutron stars (INSs) in the Galaxy.
  As the first step we discuss stochastic period evolution of INSs. We briefly
discuss how an INS's spin period evolves under influence of interaction with
turbulized interstellar medium. To investigate statistical properties of the
INS population we calculate a {\it census} of INSs in our Galaxy. Then we show
that for exponential field decay the range of minimum value of magnetic moment,
$\mu_b$: $\sim 10^{29.5}\ge \mu_b \ge 10^{28} {\rm G} {\rm cm}^3$, and the
characteristic decay time, $t_d$: $\sim 10^8\ge t_d \ge 10^7 {\rm yrs}$, can be
excluded assuming the standard initial magnetic momentum, $\mu_0=10^{30} {\rm
G} {\rm cm}^3$, if accreting INSs are observed.
  It is shown that old accreting INSs become more abundant than young cooling
INSs at X-ray fluxes below $\sim 10^{-13}$ erg cm$^{-2}$ s$^{-1}$. The weak
{\it ROSAT} sources, associated with INSs, can be young cooling objects, if the
NSs birth rate in the solar vicinity during the last $\sim 10^6$ yr was much
higher than inferred from radiopulsar observations.


title: Oxygen in the Very Early Galaxy

abstract:
  Oxygen abundances in a sample of ultra-metal-poor subdwarfs have been derived
from measurements of the oxygen triplet at 7771--5 A and OH lines in the near
UV performed in high-resolution and high signal-to-noise spectra obtained with
WHT/UES, KeckI/HIRES, and VLT/UVES. Our Fe abundances were derived in LTE and
then corrected for NLTE effects following Thevenin and Idiart (1999). The new
oxygen abundances confirm previous findings for a progressive linear rise in
the oxygen-to-iron ratio with a slope -0.33+-0.02 from solar metallicity to
[Fe/H] -3. A slightly higher slope would be obtained if the Fe NLTE corrections
were not considered. Below [Fe/H]= -2.5 our stars show [O/Fe] ratios as high as
~ 1.17 (G64-12), which can be interpreted as evidence for oxygen overproduction
in the very early epoch of the formation of the halo, possibly associated with
supernova events with very massive progenitor stars. We show that the arguments
against this linear trend given by Fulbright and Kraft (1999), based on the LTE
Fe analysis of two metal-poor stars cannot be sustained when an NLTE analysis
is performed. Using 1-D models our analysis of three oxygen indicators
available for BD +23 3130 gives consistent abundances within 0.16 dex and
average [O/Fe] ratio of 0.91.


title:
New emission phase of the Be/X-ray binary X Persei: nearly simultaneous
  spectroscopic and near-infrared observations

abstract:
  We present a series of optical spectroscopic and near-infrared photometric
observations of the Be star X Persei, from the beginning of the recent emission
phase. Our data show that after the latest extended low state (ELS), both the
equivalent width (EW) of the H\alpha emission line and the JHK luminosities
gradually increased. The recent maximum H\alpha EW and JHK magnitudes are more
than but comparable to the 1986-1989 maxima, which reflects a more extensive
and denser envelope in the new emission phase.
  The IR photometry and the H\alpha EW increase coincidently in the early stage
of the new emission phase. However, the variations in the following years,
specially in 1994 and 1995, are much different from the early variations. An
unusual variation that while the H\alpha EW in X Per increases considerably,
the JHK magnitudes decline rapidly is seen in our nearly simultaneous
pectroscopic and near-infrared observations.
  An expanding ring model is put forward to interpret the observed unusual
variations between the H\alpha EW and near-IR luminosity during the recent
emission phase of X Persei. Our results indicate that although both infrared
excess and H\alpha emission line arise from the envelope, their main
ontributors, in some cases, are likely to originate in the different part of
the envelope.


title: The VIRMOS-VLT Deep Survey

abstract:
  The aim of the VIRMOS VLT Deep Survey (VVDS) is to study of the evolution of
galaxies, large scale structures and AGNs from a sample of more than 150,000
galaxies with measured redshifts in the range 0<z<5+. The VVDS will rely on the
VIMOS and NIRMOS wide field multi-object spectrographs, which the VIRMOS
consortium is delivering to ESO. Together, they offer unprecedented multiplex
capability in the wavelength range 0.37-1.8microns, allowing for large surveys
to be carried out. The VVDS has several main aspects: (1) a deep multi-color
imaging survey over 18deg^2 of more than one million galaxies, (2) a "wide"
spectroscopic survey with more than 130,000 redshifts measured for objects
brighter than IAB=22.5 over 18deg^2, (3) a "deep" survey with 50,000 redshifts
measured to IAB=24, (4) ultra-deep" surveys with several thousand redshifts
measured to IAB=25, (5) multi-wavelength observations with the VLA and XMM.


title:
Flat-Fielding BATSE Occultation Data for use in a Hard X-Ray All Sky
  Survey

abstract:
  The BATSE mission aboard CGRO can be used to observe hard X-ray sources by
using the Earth occultation method. This method relies on measuring a step in
the count rate profile in each BATSE detector as a source rises above or sets
below the Earth's limb. A major problem in determining the step sizes (and
hence the flux) is in extracting the steps from the varying background. A
technique for flat-fielding the response of gamma ray detectors has been
developed at Southampton. The technique uses a dynamic Monte-Carlo model to
simulate the dominant components of the gamma-ray background encountered by the
experiment at any point in its orbit. A maximum likelihood imaging method is
also being developed that will be used to make a sky survey with all 9 years of
the BATSE Continuous data set in the 20 - 500 keV range. An all sky map of 25 -
35 keV emission has been made using 60 days of data and has a 3 sigma flux
sensitivity of 14 mCrab.


title: GRBS: Standard Model & Beyond

abstract:
  There have been great and rapid progresses in the field of $\gamma$-ray
bursts since BeppoSAX and other telescopes discovered their afterglows in 1997.
In this talk, the main observational facts of $\gamma$-ray bursts and their
afterglows, and the standard fireball shock model are reviewed briefly. And
then, various post-standard effects, deviations from the standard model, are
presented.


title:
STIS Echelle Observations of the Seyfert Galaxy NGC 4151: Physical
  Conditions in the Ultraviolet Absorbers

abstract:
  We have examined the physical conditions in intrinsic UV-absorbing gas in the
Seyfert galaxy NGC 4151, using echelle spectra obtained with the Space
Telescope Imaging Spectrograph (STIS). We confirm the presence of the kinematic
components detected in earlier GHRS observations as well as a new broad
absorption feature at a radial velocity of -1680 km/s. The UV continuum of NGC
4151 decreased by a factor of 4 over the previous two years, and we argue the
changes in the column density of the low ionization absorption lines associated
with the broad component at -490 km/s reflect the decrease in the ionizing
flux. Most of the strong absorption lines (e.g., N V, C IV, Si IV) from this
component are saturated, but show substantial residual flux in their cores,
indicating that the absorber does not fully cover the source of emission. Our
interpretation is that the unocculted light is due to scattering by free
electrons from an extended region, which reflects continuum, emission lines,
and absorption lines. We have been able to constrain the densities for the
kinematic components based on absorption lines from metastable states of C III
and Fe II, and/or the ratios of ground and fine structure lines of O I,C II,
and Si II. We have generated a set of photoionization models which match the
ionic column densities for each component during the present low flux state and
those seen in previous high flux states with the GHRS and STIS, confirming that
the absorbers are photoionized and respond to the changes in the continuum
flux. We have been able to map the relative radial positions of the absorbers,
and find that the gas decreases in density with distance. None of the UV
absorbers is of sufficiently large column density or high enough ionization
state to account for the X-ray absorption.


title: Mid-infrared observations of NGC 1068 with ISOCAM

abstract:
  We report on Mid-Infrared (MIR) observations of the Seyfert 2 galaxy NGC
1068, obtained with ISOCAM in low-resolution spectro-imaging mode. The spatial
resolution (around 5 arcsec) allows us to disentangle the circumnuclear
starburst regions from the emission of the active galactic nucleus (AGN). The
global spatial distribution of the Unidentified Infrared Bands (UIBs) is
similar to the cold dust component, traced by the 450 microns emission and the
gaseous component obtained from the CO(1-0) map. However, a shift between the
maximum of the UIB and 450 microns emission is clearly seen in our maps. The
UIBs in the MIR (5-16 microns) originate almost exclusively from the starburst
regions in the galactic disk with an emission peaking at the extremity of the
stellar/ gaseous bar at a distance of 1 kpc from the AGN. The spectrum of the
nucleus is characterized over the whole 5-16 microns range by a strong
continuum which can be fitted with a power law of index -1.7. Moreover, the
high [NeIII]/[NeII] ratio (>2.5) in the nuclear region argues for a hard
radiation field from the AGN. Observations indicate that the AGN in NGC 1068
contributes less than 5% to the total integrated UIB emission even though its
hot dust continuum contributes as much as 75% to the total MIR flux. On the
contrary, the nuclear contribution to the cold dust emission decreases
considerably at submillimeter wavelengths and does not represent more than 25%
of the total integrated emission at 450 microns.


title: Gamma Ray Pulsars: Observations

abstract:
  High-energy gamma rays are a valuable tool for studying particle acceleration
and radiation in the magnetospheres of energetic pulsars. The six or more
pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak
structures (suggesting a broad cone of emission); gamma rays are frequently the
dominant component of the radiated power; and all the spectra show evidence of
a high-energy turnover. Unless a new pulsed component appears at higher
energies, progress in gamma-ray pulsar studies will be greatest in the 1-20 GeV
range. Ground-based telescopes whose energy ranges extend downward toward 10
GeV should make important measurements of the spectral cutoffs. The Gamma-ray
Large Area Space Telescope (GLAST), now in planning for a launch in 2005, will
provide a major advance in sensitivity, energy range, and sky coverage.


title:
Measuring Time-Dependence of Dark Energy Density from Type Ia Supernova
  Data

abstract:
  Observations of high redshift supernovae imply an accelerating Universe which
can only be explained by an unusual energy component such as vacuum energy or
quintessence. To assess the ability of current and future supernova data to
constrain the properties of the dark energy, we allow its density to have
arbitrary time-dependence, $\rho_X(z)$. This leads to an equation of state for
the dark energy, $w_X(z)=p_X(z)/\rho_X(z)$, which is a free function of
redshift $z$. We find that current type Ia supernova (SNe Ia) data are
consistent with a cosmological constant, with large uncertainties at $z\ga
0.5$. We show that $\rho_X(z)/\rho_X(z=0)$ can be measured reasonably well to
about $z=1.5$ using type Ia supernova data from realistic future SN Ia pencil
beam surveys, provided that the weak energy condition (energy density of matter
is nonnegative for any observer) is imposed.
  While it is only possible to differentiate between different models (say,
quintessence and k-essence) at $z \la 1.5$ using realistic data, the correct
trend in the time-dependence of the dark energy density can be clearly detected
out to $z=2$, even in the presence of plausible systematic effects. This would
allow us to determine whether the dark energy is a cosmological constant, or
some exotic form of energy with a time-dependent density.


title:
Application of an objective method for the identification of Young Star
  Groupings in spiral galaxies

abstract:
  We present some results of the application of our automatic technique for the
identification of Young Star Groupings (YSGs) in spiral galaxies. In this
report we discuss our new results for NGC 3377a and NGC 3507 together with
previously published data of NGC 7217, NGC 1058 and UGC 12732. The aim of this
ongoing research is to obtain a wide sample of homogeneous data for the study
of the YSGs and their relationships with the properties of their parent
galaxies, using only objective identifications.


title: Secular Bar-Mode Evolution and Gravitational Waves From Neutron Stars

abstract:
  The secular instability and nonlinear evolution of the m=2 f-mode (bar-mode)
driven by gravitational radiation reaction in a rapidly rotating, newly formed
neutron star are reviewed. There are two types of rotating bars which generate
quite different gravitational waveforms: those with large internal rotation
relative to the bar figure (Dedekind-like bars) have GW frequency sweeping
downward during the evolution, and those with small internal rotation
(Jacobi-like) have GW frequency sweeping upward. Various sources of viscosity
(which affects the instability) in hot nuclear matter are reexamined, and the
possible effect of star-disk coupling on the bar-mode instability is also
discussed.


title: Young Supernova Remnants: Issues and Prospects

abstract:
  After reviewing recent work on the dynamics of young supernova remnants
(YSNRs) and discussing how YSNRs can be used as physics laboratories, I discuss
several challenges: Where are the very young SNRs in the Galaxy? Can very young
SNRs produce gamma ray bursts? The Connections Challenge: Can one infer the
nature of the supernova and its progenitor star from observations of the YSNR?


title:
A Doppler Shift model to explain the Cyclotron Line Variability in X-Ray
  Pulsars

abstract:
  A simple model to explain the phase-dependence of the cyclotron absorption
line observed in many X-Ray pulsars is presented. It includes several
relativistic effects, namely gravitational redshift, gravitational light
deflection, and - most important - doppler shift of the photon energy in the
infalling plasma. It is shown that previous estimates of neutron star magnetic
fields neglecting the last effect give results which are too small by about a
factor of two. Finally the developed equations are used to determine the
neutron star radius and magnetic field of Her X-1, but the large uncertainties
in the geometry prevent the results from seriously constraining the parameters.


title: Evidence for a Sudden Magnetic Field Reconfiguration in SGR 1900+14

abstract:
  We report the detection of large flux changes in the persistent X-ray flux of
SGR 1900+14 during its burst active episode in 1998. Most notably, we find a
factor ~700 increase in the non-burst X-ray flux following the August 27th
flare, which decayed in time as a power-law. Our measurements indicate that the
pulse fraction remains constant throughout this decay. This suggests a global
flux enhancement as a consequence of the August 27th flare rather than
localized heating. While the persistent flux has since recovered to the
pre-outburst level, the pulse profile has not. The pulse shape changed to a
near sinusoidal profile within the tail of the August 27th flare (in
gamma-rays) and this effect has persisted for more than 1.5 years (in X-rays).
The results presented here suggest the magnetic field of the neutron star in
SGR 1900+14 was significantly altered (perhaps globally) during the giant flare
of August 27.


title: Summary: Modes of Star Formation

abstract:
  This contribution summarizes briefly the main topics covered at this
wide-ranging conference. Much of the evidence presented indicates that star
formation occurs in discrete episodes or bursts that produce stellar groupings
of all sizes, the fossil remnants of which make up the present stellar
populations of galaxies.


title: Event Rates for Binary Inspiral

abstract:
  Double compact objects (neutron stars and black holes) found in binaries with
small orbital separations are known to spiral in and are expected to coalesce
eventually because of the emission of gravitational waves. Such inspiral and
merger events are thought to be primary sources for ground based
gravitational-wave interferometric detectors (such as LIGO). Here, we present a
brief review of estimates of coalescence rates and we examine the origin and
relative importance of uncertainties associated with the rate estimates. For
the case of double neutron star systems, we compare the most recent rate
estimates to upper limits derived in a number of different ways. We also
discuss the implications of the formation of close binaries with two
non-recycled pulsars.


title:
KiloHertz QPO and Gravitational Wave Emission as the Signature of the
  Rotation and Precession of a LMXB Neutron Star Near Breakup

abstract:
  The basic theory of torque free precession (TFP) of the outer crust of a
neutron star (NS) as the signature of the approach to NS breakup is a viable
explanation of the uniform properties of kHz Quasi-periodic Oscillations (QPO)
observed in X-rays emitted by Low Mass X-ray Binary (LMXB) sources. The theory
outlined in this paper relates the intrinsic properties of NS structure to the
observed kHz frequencies. The range of kHz frequencies and the observed quality
factors (Qs) are also explained by this simple dynamical model. A scenario that
begins with the melting of the inner crust of an LMXB NS creates the conditions
necessary for the generation of kHz QPO. The theory relates the ratio of the
observed kHz frequencies to the ratios of the components of the moments of
inertia of the NS, thereby tightly constraining the equation of state (EOS) of
NS matter (polytrope index ~1.0). The TFP model is in strong contrast to
existing models which primarily relate the kHz QPO phenomenon to the physics of
gas dynamics near the inner edge of the accretion disk and the transition flow
onto the surface of the NS. We suggest the possibility of the direct detection
of very low frequency (~1 kHz) radio waves from magnetic dipole radiation and
also predict kHz gravitational wave emission from the LMXB Sco X-1 that may be
detectable by LIGO. The high accretion rates consistent with the predicted GW
emission indicate the likely conversion of some LMXBs to maximally rotating
Kerr black holes (BH) and further suggest that these systems are progenitors of
some gamma-ray bursts (GRB).


title: Evidence for Expanding Superbubbles in a Galaxy at z=0.7443

abstract:
  The intervening z=0.7443 Mg II absorption system in the spectrum of MC
1331+170 shows an unusual series of line pairs, each with velocity separations
of 30 km/s. These lines could be explained as the shells of expanding
superbubbles residing in the outer regions of an edge-on spiral galaxy visible
in the optical image of the MC 1331+170 field. The color and brightness of this
galaxy make it the most likely candidate z=0.7443 absorber, though two other
galaxies in the quasar field could also be contributing to the Mg II absorption
profile. Kinematic models of absorption from compact groups and galaxy pairs
produce profiles largely inconsistent with the observed Mg II spectrum.
Superbubbles would naturally generate more regular structures such as those
observed. Photoionization models of the superbubble shell are consistent with
the observed profile for many realistic physical conditions. In a pure
superbubble model, the large velocity spread of the Mg II absorption system is
inconsistent with the expected spread of a quiescent, rotating disk. This
requires unusual kinematics within the host galaxy, perhaps due to a recent
interaction.


title: NGC 3065: A Certified LINER With Broad, Variable Balmer Lines

abstract:
  Motivated by the X-ray properties of the galaxy NGC 3065, we have obtained
new optical spectra which reveal that it has a low-ionization nuclear
emission-line region (LINER) as well as broad Balmer emission lines,
establishing it as an active galactic nucleus. We also examined an older
spectrum from the CfA Redshift Survey which, lacking broad Balmer lines,
indicates that they appeared some time after 1980. Thus NGC 3065 joins the set
of LINERs with broad, variable Balmer lines, which includes such well-known
galaxies as NGC 1097 and M81. Inspired by the sometimes double-peaked profiles
of the variable Balmer lines in other LINERs, we speculate that the broad
Balmer lines of NGC 3065 also come from an accretion disk. We illustrate the
plausibility of this hypothesis by fitting a disk model to the observed
H$\alpha$ profile. We also estimate the mass of the central black hole as
(9+/-4) 10^7 M_sol from the properties of the host galaxy, which leads to the
conclusion that the accretion rate is only 2 10^{-4} times the Eddington value,
a property that appears to be common among LINERs. At such a low relative
accretion rate the inner accretion disk can turn into a vertically-extended ion
torus, which can illuminate the outer, thin disk and power the broad-line
emission. The reason for the sudden appearance of broad Balmer lines is an open
question, although we suggest two possible explanations: tidal disruption of a
star or a sudden transition in the structure of the accretion disk.


title:
AGN Population at 10^-13 erg s-1 cm-2: Results from Optical
  Identification of ASCA Surveys

abstract:
  In this paper, results of optical identification of ASCA surveys are
summarized. To understand luminous AGNs in the z<1 universe, the ASCA AGN
sample is still better than samples of AGNs from deep Chandra or XMM-Newton
surveys. Combining the identified sample of AGNs from ASCA Large Sky Survey and
Medium Sensitivity Survey, the sample of hard X-ray selected AGNs have been
expanded up to about 80 AGNs above the flux limit of 10^{-13} erg s^{-1}
cm^{-2} in the 2-10keV band. One fifth of the ASCA AGNs are absorbed
narrow-line AGNs. The luminosity distribution of the absorbed AGNs is limited
below 10^{45} erg s^{-1}, though there are 14 non-absorbed broad-line AGNs are
detected above the luminosity. The result suggests lack of absorbed luminous
AGNs (deficiency of type 2 QSO).


title:
Spatially resolved spectroscopy of Cassiopeia A with MECS on board
  BeppoSAX

abstract:
  We have performed the first detailed spatially resolved spectroscopy of Cas A
in the 1.6-10 keV energy range, using data taken with the MECS spectrometer on
board the BeppoSAX Observatory. We performed a spatial deconvolution of the
data and eventually generated a set of spectra, covering a region of about 3
arcmin radius around the centre of Cas A. The results obtained by fitting these
spectra using a non-equilibrium ionisation plasma model and a power law, are:
(i) a single thermal component is sufficient to fit all the spectra; (ii) kT is
rather uniformly distributed with a minimum in the east and a maximum in the
west, and no evidence is found for high kT expected from the interaction of the
main shock with the ISM; (iii) from the distribution of the values of the
ionisation parameter n_et we infer the presence of two distinct components: the
first (a) in the range 1-10 cm^(-3), the second (b) with values ten times
higher; if we associate component a to the CSM and component b to the ejecta,
the mass ratio M(a)/M(b)<= 1/10 indicates a progenitor star that lost only a
small fraction of the envelope during its pre-SN life. In this hypothesis the
distribution of component b across the remnant suggests that the explosion was
not spherically symmetric; (iv) the distribution of abundances indicates that
we are detecting a CSM component with almost solar composition, and an ejecta
component enriched in heavier elements. Abundances found for alpha-elements are
consistent with the current view that Cas A was produced by the explosion of a
massive star.


title: Mechanisms and sites of ultra high energy cosmic ray origin

abstract:
  We shortly discuss several astrophysical scenarios leading to cosmic ray
acceleration up to extremely high energies reaching the scale of 10^{20} eV.
The processes suggested in the literature include acceleration at relativistic
jet terminal shocks and shear boundary layers, shocks in large scale accretion
flows onto supergalactic cosmic structures, particle reflections from
ultra-relativistic shocks postulated to exist in sources of gamma ray bursts,
the processes involving the neutron star rotating magnetospheres and dormant
quasars. Some of these objects can explain cosmic rays with highest energies if
one tunes the model parameters to limits enabling the highest acceleration
efficiency. We also note that some of the considered processes allow for
acceleration efficiency in the Hillas diagram, beta, to be much larger than
unity. The present paper is based on a review talk presented during the
European Cosmic Ray Symposium in Lodz (2000).


title:
Spectroscopy of Stellar Jets, Outflows, and Young Stellar Objects with
  the Infrared Space Observatory

abstract:
  The Infrared Space Observatory (ISO) was an extremely successful european
space mission that gave us an unparallel view of the Universe in the infrared,
and provided us with hundreds of observations of star forming regions and
bipolar outflows. Three of the instrument teams, in charge of the infrared
camera (CAM) and the two spectrometers at short and long wavelengths (SWS and
LWS respectively), used a significant fraction of their guarantee time to study
YSOs and outflows spectroscopically. In here, I will briefly review some of
their main findings, particularly the detection of water, H2 rotational
emission lines and the presence of other complex molecules. I will present new
spectroscopic results on HH 1-2, HH 7-11 and Cep E, and their sources. And
finally, I will discuss some of the general trends derived from these
observations and their relevance in understanding the emission from these
objects using J and C shock models.


title: Are mirror planets opaque?

abstract:
  Over the last few years, many close orbiting ($\sim 0.05$ A.U.) large mass
planets ($\sim M_{J}$) of nearby stars have been discovered. Their existence
has been inferred from tiny Doppler shifts in the light from the star and in
one case a transit has been observed. Because ordinary planets are not expected
to be able to form this close to ordinary stars due to the high temperatures,
it has been speculated that the close-in large planets are in fact exotic
heavenly bodies made of mirror matter. We show that the accretion of ordinary
matter onto the mirror planet (from e.g.the solar wind from the host star)
should make the mirror planet opaque to ordinary radiation with an effective
radius ($R_p$) large enough to explain the measured size of the transiting
close-in extrasolar planet, HD209458b. Furthermore we obtain the rough
prediction that $R_{p} \propto \sqrt{{T_s\over M_p}}$ (where $T_s$, is the
surface temperature of the ordinary matter in the mirror planet and $M_p$ is
the mass of the mirror planet) which will be tested in the near future as more
transiting planets are found. We also show that the mirror world interpretation
of the close-in extra solar planets explains the low albedo of $\tau$ Boo b
because the large estimated mass of $\tau$ Boo b ($\sim 7M_J$) implies a small
effective radius of $R_p \approx 0.5R_J$ for $\tau$ Boo.


title:
Entropic-acoustic instability of shocked Bondi accretion I. What does
  perturbed Bondi accretion sound like ?

abstract:
  In the radial flow of gas into a black hole (i.e. Bondi accretion), the
infall of any entropy or vorticity perturbation produces acoustic waves
propagating outward. The dependence of this acoustic flux on the shape of the
perturbation is investigated in detail. This is the key process in the
mechanism of the entropic-acoustic instability proposed by Foglizzo & Tagger
(2000) to explain the instability of Bondi-Hoyle-Lyttleton accretion. These
acoustic waves create new entropy and vorticity perturbations when they reach
the shock, thus closing the entropic-acoustic cycle. With an adiabatic index
1<gamma<=5/3, the linearized equations describing the perturbations of the
Bondi flow are studied analytically and solved numerically. The fundamental
frequency of this problem is the cut-off frequency of acoustic refraction,
below which ingoing acoustic waves are refracted out. This cut-off is
significantly smaller than the Keplerian frequency at the sonic radius and
depends on the latitudinal number l of the perturbations. When advected
adiabatically inward, entropy and vorticity perturbations trigger acoustic
waves propagating outward, with an efficiency which is highest for non radial
perturbations l=1. The outgoing acoustic flux produced by the advection of
vorticity perturbations is always moderate and peaks at rather low frequency.
By contrast, the acoustic flux produced by an entropy wave is highest close to
the refraction cut-off. It can be very large if gamma is close to 5/3. These
results suggest that the shocked Bondi flow with gamma=5/3 is strongly unstable
with respect to the entropic-acoustic mechanism.


title: BeppoSAX spectroscopy of the luminous X-ray sources in M33

abstract:
  The nearby galaxy M33 was observed by the imaging X-ray instruments on-board
BeppoSAX. Two observations at different phases of the 105.9 day intensity cycle
of the luminous central source X-8 failed to reveal the expected modulation,
suggesting that it is probably transitory. Similar behavior has been observed
from several X-ray binary sources. This strengthens somewhat the idea that M33
X-8 is a black hole accreting from a binary companion. The 0.2-10 keV spectrum
of M33 X-8 can best be modeled by an absorbed power-law with a photon index of
1.89 +0.40 -0.79 and a disk-blackbody with a temperature, kT, of 1.10 +/0 0.05
keV and a projected inner-disk radius of 55.4 +6.0 -7.7 km. This spectral shape
is in good agreement with earlier ASCA results. The 2-10 keV spectra of M33
X-4, X-5, X-7, X-9 and X-10 are all consistent with power-law or bremsstrahlung
models, whilst that of X-6 appears to be significantly more complex and may be
reasonably well modeled with a disk-blackbody with kT = 1.7 +/- 0.2 keV and a
projected inner-disk radius of 7 +/- 2 km. The spectrum of M33 X-9 is rather
hard with a photon index of 1.3. Compared to earlier Einstein and ROSAT
observations, M33 X-7 and X-9 varied in intensity, M33 X-4, X-6, and X-10 may
have varied and M33 X-5 remained constant.


title: Lensing Constraints on the Cores of Massive Dark Matter Halos

abstract:
  The statistics of wide-separation (6'' < theta < 15'') gravitational lenses
constrain the amount of mass in the cores of dark matter halos on group and
cluster mass scales. For a family of halo models with a central cusp $\rho
\propto r^{-alpha}$ (1.0 <= alpha <= 1.9), the lack of wide-separation lenses
in the large Cosmic Lens All-Sky Survey yields an upper limit on the fraction
of the halo mass that is contained within ~4% of the virial radius, f_{core} <
0.023 (95% confidence level, LCDM). This limit offers an important test of the
cold dark matter paradigm. While the halo profiles derived from numerical
simulations appear to be consistent with this upper limit, larger surveys
currently underway such as the 2dF and SDSS should detect wide-separation
lenses and thus provide a measurement of the core mass fraction in massive dark
matter halos.


title:
Evidence for Residual Material in Accretion Disk Gaps: CO Fundamental
  Emission from the T Tauri Spectroscopic Binary DQ Tau

abstract:
  We present the discovery of CO fundamental ro-vibrational emission from the
classical T Tauri spectroscopic binary DQ Tau. The high-resolution infrared
echelle spectra reveal emission lines from both the v=1 and v=2 vibrational
levels with line widths of roughly 70 km/s. The average CO excitation
temperature is approximately 1200 K. We model the spectra as arising from gas
in Keplerian rotation about the center-of-mass of the binary. The disk model
requires gas with an average surface density of 5 x 10-4 g cm-2 that extends
outward to 0.5 +/- 0.1 AU and inward to at least 0.1 AU from the
center-of-mass. The radial extent for the emitting gas is close to the
predicted size of the gap in the DQ Tau accretion disk that is expected to be
dynamically cleared by the binary. We interpret these results, and previous
modeling of DQ Tau's spectral energy distribution, as evidence for a small
amount (~ 1e-10 Msun) of diffuse material residing within the optically-thin
disk gap. Thus dynamical clearing has not been completely efficient in the DQ
Tau binary. We suggest that the material is associated with a flow from the
circumbinary disk which feeds the ongoing accretion at the stellar surfaces.


title: BeppoSAX observation of the rich cluster of galaxies Abell 85

abstract:
  We report the observation of the Intra-Cluster Medium (ICM) of Abell 85 by
the X-ray satellite BeppoSAX. We have both analysed the spectrum obtained in
the central 8 arcmin circular region centred on the Very Steep Spectrum Radio
Source (VSSRS) and the spectra from a number of sub-regions. Analysis of the
spectra allowed us to independently obtain new estimates of the temperature,
metallicity and line-of-sight hydrogen density column, both globally
(T=6.6\pm0.3 keV, Z = 0.38\pm0.06 Z_\odot and N_H = 5.5^+0.9_-0.7 10^20 cm^-2)
and locally. These measures are in good agreement with previous measures based
on ROSAT and ASCA data. In the region of the VSRSS, we have tried to
disentangle the thermal from the non-thermal X-ray emission. Although we could
not do this unambiguously, we have nonetheless estimated the extended magnetic
field using the radio spectrum available for this region. We obtain a lower
limit intensity of 0.9 \mu G, consistent with our previous estimate. We also
derive alpha-elements/iron abundance ratios that turn out to be higher than 1.
Such a result tends to support the burst model for elliptical galaxies, where a
strong galactic wind develops early in the galaxy history and type II
supernovae (SN) may have the main role in the enrichment of the ICM. A
two-temperature ICM model was fitted in the central region yielding a main
component with roughly the mean cluster temperature and a cooler component with
temperature less than 0.1 keV.


title: The First Turbulence

abstract:
  Chaotic, eddy-like motions dominated by inertial-vortex forces begin
immediately at Planck scales in a hot big-bang cosmological model. This
quantum-gravitational-dynamics epoch produced not only the first
space-time-energy of the universe but the first large Reynolds number
turbulence and turbulent mixing with Kolmogorov and Batchelor-Obukhov-Corrsin
velocity and temperature gradient spectra. Strong-force-freeze-out and
inflation produced the first fossil temperature turbulence by stretching the
fluctuations beyond the horizon scale ct of causal connection at light speed c
in time t. The spectrum increases toward a maximum at the smallest (fossilized
Planck) scales, contrary to either the flat Harrison-Zel'dovich form usually
assumed or Tilted forms with maxima at large (fossilized strong-force) scales
used to explain observed plasma epoch temperature fluctuations as acoustic. A
second transition to turbulence was inhibited by buoyancy forces from the first
structures, as indicated by observations that dT/T in the cosmic microwave
background radiation is only 10^-5 except at the spectral peak and increases
smoothly as wavenumber k^1/6. The peak is therefore due to gravitational
structure not sound.


title: Intrinsic Absorption in Radio-Selected QSOs

abstract:
  Moderate resolution spectra have been recorded for a sample of radio-selected
QSOs (z=2.5) discovered in the ``Faint Images of the Radio Sky at Twenty
centimeters'' (FIRST) VLA survey. This work is motivated by the study of a
heterogeneous set of QSO absorption line spectra that showed that as many as
36% of the absorbers normally thought to be intergalactic are correlated with
physical properties of the background QSO, including the radio source spectral
index. Spectra were taken for 24 newly discovered quasars in order to test this
finding on a more homogeneous data set. The spectra have been searched for the
most frequently observed absorption lines. The absorption line properties are
compared to the radio properties of the quasars. The primary results are
summarized as follows: 1) an excess of CIV absorbers in flat-spectrum quasars
as compared to steep-spectrum quasars is confirmed (based on a total sample of
165 systems), 2) a small excess of high-velocity CIV absorbers is seen in
radio-quiet QSOs as compared to radio-loud quasars, and 3) the Sloan Digital
Sky Survey QSO spectra will allow for the detection of a high-velocity, narrow,
intrinsic population of absorbers that is as small as 7% of the CIV absorber
population in QSOs at z=2.5.


title: Quasar Absorption Lines as a Function of Quasar Orientation Measures

abstract:
  We present high resolution radio data at 3.5 and 20 cm from the VLA in the A
configuration for 144 quasars with known CIV absorption line properties. Using
these measurements, we compare and contrast a number of quasar orientation
indicators. These quantities are used to study the velocity distribution of CIV
absorption lines as a function of quasar orientation measures. That there is an
excess of narrow, high-velocity CIV absorbers in flat-spectrum quasars as
compared to steep-spectrum quasars is confirmed. Orientation indicators that
are not based upon spectral indices (e.g. R_V and the core-to-lobe ratio) do
not show the same effect. These seemingly contradictory results may be
reconciled if the absorber distribution is not strictly a function of
orientation, but rather a function of intrinsic radio properties that may or
may not be good orientation indicators.


title: Deep imaging of Q2112+059: A bright host galaxy but no DLA absorber

abstract:
  In a ongoing programme aimed at studying galaxy counterparts of Damped
Ly-alpha Absorbers (DLAs) we have obtained high resolution deep I-band imaging
data of the field around the z_em = 0.457 BAL QSO Q2112+059. In the literature
this QSO is listed to have a candidate DLA at z_abs = 0.2039 along the line of
sight. After subtraction of the QSO Point Spread Function (PSF) we detect a
galaxy centred on the position of Q2112+059. To help answer whether this galaxy
is the DLA or the QSO host galaxy we retrieved a GHRS spectrum of Q2112+059
from the HST-archive. This spectrum shows that there is no Ly-alpha absorption
line at z_abs = 0.2039. This fact in combination with the perfect alignment on
the sky of the galaxy and Q2112+059 lead us to the conclusion that the galaxy
must be the host galaxy of Q2112+059.
  The host galaxy of Q2112+059 is bright (M_I^obs = -23.6), and has a radial
profile well fitted by a {\it modified Hubble + de Vaucouleurs} profile with
R_c = 0.5 kpc and R_e = 3.6 kpc. Our results are well in line with the
conclusion of earlier work done at lower redshifts, that bright low redshift
QSOs preferentially reside in luminous, elliptical galaxies. The host of
Q2112+059 is however, despite it's brightness, very compact when compared to
early type galaxies at lower redshifts.


title: Revealing the Dusty Warm Absorber in MCG--6-30-15 with the Chandra HETG

abstract:
  We present detailed evidence for a warm absorber in the Seyfert 1 galaxy
MCG--6-30-15 and dispute earlier claims for relativistic O line emission. The
HETG spectra show numerous narrow, unresolved (FWHM < 200 km/s) absorption
lines from a wide range of ionization states of N, O, Mg, Ne, Si, S, Ar, and
Fe. The O VII edge and 1s^2--1snp resonance line series to n=9 are clearly
detected at rest in the AGN frame. We attribute previous reports of an
apparently highly redshifted O VII edge to the 1s^2--1snp (n > 5) O VII
resonance lines, and a neutral Fe L absorption complex. The shape of the Fe L
feature is nearly identical to that seen in the spectra of several X-ray
binaries, and in laboratory data. The implied dust column density agrees with
that obtained from reddening studies, and gives the first direct X-ray evidence
for dust embedded in a warm absorber. The O VIII resonance lines and weak edge
are also detected, and the spectral rollover below 2 keV is explained by the
superposition of numerous absorption lines and edges. We identify, for the
first time, a KLL resonance in the O VI photoabsorption cross section, giving a
measure of the O VI column density. The O VII (f) emission detected at the
systemic velocity implies a covering fraction of ~5% (depending on the observed
vs. time-averaged ionizing flux). Our observations show that a dusty warm
absorber model is not only adequate to explain all the spectral features > 0.48
keV (< 26 \AA) the data REQUIRE it. This contradicts the interpretation of
Branduardi-Raymont et al. (2001) that this spectral region is dominated by
highly relativistic line emission from the vicinity of the black hole.


title:
X-ray energy and power spectra of Seyfert 1 and Narrow Line Seyfert 1
  galaxies: comparison to Black Hole Binaries

abstract:
  I review observational data on X-ray energy spectra and variability of
Seyfert 1 and Narrow Line Seyfert 1 galaxies, and compare them to black hole
binary (BHB) systems. There seems to be greater similarity of time averaged
properties (i.e. energy spectra) than time variability between the supermassive
and stellar-mass black hole accreting systems.
  Energy spectra of Seyfert 1 galaxies are similar to BHB in low/hard state,
but power spectra of Sy 1 are intermediate in properties between those for hard
and soft states of BHB.
  There is growing evidence that NLSy 1 are accreting at higher accretion rates
than Sy 1, which supports the view that they correspond to soft states of BHB.
Again, they are more similar to their stellar counterparts with respect to
their spectral properties than to the timing properties.
  I briefly outline some theoretical ideas which suggest explanations of those
differences.


title:
The Postcollapse Equilibrium Structure of Cosmological Haloes in a
  Low-Density Universe

abstract:
  An analytical model is presented for the postcollapse equilibrium structure
of virialized objects which condense out of a low-density cosmological
background universe, either matter-dominated or flat with a cosmological
constant. This generalizes the model we derived previously for an Einstein-de
Sitter (EdS) universe. The model is based upon the assumption that cosmological
haloes form from the collapse and virialization of top-hat density
perturbations and are spherical, isotropic, and isothermal. This leads to the
prediction of a unique, nonsingular, truncated isothermal sphere (TIS), a
particular solution of the Lane-Emden equation (modified for nonzero
cosmological constant). The size and virial temperature are unique functions of
the mass and redshift of formation of the object for a given background
universe. The central density is roughly proportional to the critical density
of the universe at the epoch of collapse. This TIS model is in good agreement
with observations of the internal structure of dark matter--dominated haloes on
scales ranging from dwarf galaxies to X-ray clusters. It also reproduces many
of the average properties of haloes in simulations of the Cold Dark Matter
(CDM) model to good accuracy, suggesting that it is a useful analytical
approximation for haloes which form from realistic initial conditions. Our TIS
model matches the density profiles of haloes in CDM N-body simulations outside
the innermost region, while avoiding the steep central cusp of the latter which
is in apparent conflict with observations. The TIS model may also be relevant
to nonstandard CDM models, like self-interacting dark matter, recently proposed
to resolve this conflict.


title: Models for Galactic cosmic-ray propagation

abstract:
  A new numerical model of particle propagation in the Galaxy has been
developed, which allows the study of cosmic-ray and gamma-ray production and
propagation in 2D or 3D, including a full reaction network. This is a further
development of the code which has been used for studies of cosmic ray
reacceleration, Galactic halo size, antiprotons and positrons in cosmic rays,
the interpretation of diffuse continuum gamma rays, and dark matter. In this
paper we illustrate recent results focussing on B/C, sub-Fe/Fe, ACE radioactive
isotope data, source abundances and antiprotons. From the radioactive nuclei we
derive a range of 3-7 kpc for the height of the cosmic-ray halo.


title:
Comment on the first-order Fermi acceleration at ultra-relativistic
  shocks

abstract:
  The first-order Fermi acceleration process at an ultra-relativistic shock
wave is expected to create a particle spectrum with the unique asymptotic
spectral index sigma_{gamma >> 1} approximately 2.2. Below, we discuss this
result and differences in its various derivations, which -- explicitly or
implicitly -- always require highly turbulent conditions downstream of the
shock. In the presence of medium amplitude turbulence the generated particle
spectrum can be much steeper than the above asymptotic one. We also note
problems with application of the pitch angle diffusion model for particle
transport near the ultra-relativistic shocks.


title: On The Cosmic Origins Of Carbon & Nitrogen

abstract:
  We employ analytical and numerical chemical evolution models to study
observed trends in abundance ratios involving carbon, nitrogen, and oxygen.
Several sets of published stellar yields for both intermediate-mass and massive
stars are considered, and the most appropriate sets are selected through the
use of analytical models. These yields are then used in the numerical models to
match observed data trends in C/O, N/O, and O/H. We conclude that the principal
production site for carbon is massive stars, while that for nitrogen is
intermediate-mass stars.


title:
Observational Tests Of Intermediate Mass Star Yields Using Planetary
  Nebulae

abstract:
  This paper summarizes a project designed to study abundances in a sample of
planetary nebulae representing a broad range in progenitor mass and
metallicity. We collect abundances of C, N, and O determined for the entire
sample and compare them with theoretical predictions of planetary nebula
abundances from a grid of intermediate-mass star models. We find very good
agreement between observations and theory, lending strong support to our
current understanding of nucleosynthesis in stars with progenitor masses below
8 solar masses. This agreement between observation and theory also supports the
validity of published stellar yields of C and N in the study of the abundance
evolution of these two elements.


title: The Curious Adventure of the Ultrahigh Energy Cosmic Rays

abstract:
  These lectures discuss the mysteries involving the production and
extragalactic propagation of ultrahigh energy cosmic rays and suggested
possible solutions.


title:
Noise estimation in CMB time-streams and fast map-making. Application to
  the BOOMERanG98 data

abstract:
  We describe here an iterative method for jointly estimating the noise power
spectrum from a CMB experiment's time-ordered data, together with the
maximum-likelihood map. We test the robustness of this method on simulated
Boomerang datasets with realistic noise.


title: Recovering Physical Parameters from Galaxy Spectra Using MOPED

abstract:
  We derive physical parameters of galaxies from their observed spectrum, using
MOPED, the optimized data compression algorithm of Heavens, Jimenez & Lahav
2000. Here we concentrate on parametrising galaxy properties, and apply the
method to the NGC galaxies in Kennicutt's spectral atlas. We focus on deriving
the star formation history, metallicity and dust content of galaxies. The
method is very fast, taking a few seconds of CPU time to estimate 17
parameters, and so specially suited to study of large data sets, such as the
Anglo-Australian 2 degree field galaxy survey and the Sloan Digital Sky Survey.
Without the power of MOPED, the recovery of star formation histories in these
surveys would be impractical. In the Kennicutt atlas, we find that for the
spheroidals a small recent burst of star formation is required to provide the
best fit to the spectrum. There is clearly a need for theoretical stellar
atmospheric models with spectral resolution better than 1\AA if we are to
extract all the rich information that large redshift surveys contain in their
galaxy spectra.


title:
New Results from a Survey of Galactic Outflows in Nearby Active Galactic
  Nuclei

abstract:
  Recent results from a multiwavelength survey of spatially resolved outflows
in nearby active galaxies are presented. Optical Fabry-Perot and long-slit
spectroscopic data are combined with VLA and ROSAT images, when available, to
probe the warm, relativistic and hot gas components involved in the outflow.
The emphasis is put on objects which harbor wide-angle galactic-scale outflows
but also show evidence at radio or optical wavelengths for collimated jet-like
phenomena (e.g., Circinus, NGC 4388, and to a lesser extent NGC 2992). Our
results are compared with the predictions from published jet-driven thermal
wind models.


title: OHS: OH-airglow Suppressor for the Subaru Telescope

abstract:
  This paper describes an OH-airglow Suppressor (OHS) for the infrared Nasmyth
focus of the Subaru telescope. OHS has the capability of eliminating 224
airglow-lines in the $J$- and $H$-bands, which are major sources of background
radiation at near-infrared wavelengths up to 2 $\mu$m. Specifically, it is a
pre-optics system installed between the telescope and an infrared
camera/spectrograph (CISCO). The suppressor reduces sky background emissions to
1/25 and its throughput is 40%. As a result, the S/N gain achieved with OHS is
more than 1 mag compared to the typical spectroscopic approach. The limiting
magnitude measured during a test observing run was found to be $H$ = 21.1 mag
($\lambda/\Delta\lambda$ = 210, S/N = 5) in the standard 4000 s exposure
sequence.


title: SHEEP: the ASCA 5-10 keV survey

abstract:
  We present the first results of the hard (5-10 keV) ASCA GIS survey SHEEP
(Search for the High Energy Extragalactic Population).
  We have analysed 149 fields covering an area of 39 sq. deg detecting 69
sources. Several of these appear to be associated with QSOs and Seyfert-1
galaxies but with hard X-ray spectra, probably due to high absorption. Indeed,
the hardness ratio analysis shows that the spectra of the majority of our
sources can be represented with a ``scatterer'' model similar to obscured
Seyfert galaxies locally.
  According to this model, our sources present high intrinsic absorption
(logN_H~23) but also significant amounts of soft X-ray emission coming from
scattered light.


title: Local Group Velocity Versus Gravity: Nonlinear Effects

abstract:
  We use numerical simulations to study the relation between the velocity of
the Local Group and its gravitational acceleration. This relation serves as a
test for the kinematic origin of the CMB dipole and as a method for estimating
beta. We calculate the misalignment angle between the two vectors and compare
it to the observed value for the PSCz survey. The latter value is near the
upper limit of the 95% confidence interval for the angle; therefore, the
nonlinear effects are unlikely to be responsible for the whole observed
misalignment. We also study the relation between the amplitudes of the LG
velocity and gravity vectors. In an Omega=1 Universe, the smoothed gravity of
the LG turns out to be a biased low estimator of the LG (unsmoothed) velocity.
In an Omega=0.3 Universe, the estimator is biased high. The discussed biases
are, however, only a few per cent, thus the linear theory works to good
accuracy. The gravity-based estimator of the LG velocity has also a scatter
that limits the precision of the estimate of beta in the LG velocity-gravity
comparisons. The random error of beta due to nonlinear effects amounts to
several per cent.


title: BeppoSAX Observations of the Seyfert-2 Galaxies NGC 7172 and ESO 103-G35

abstract:
  We investigate the X-ray spectra of the type-2 Seyfert galaxies NGC 7172 and
ESO 103-G35, using BeppoSAX observations, separated by approximately one year.
We find that the X-ray spectra of both NGC 7172 and ESO 103-G35 can be well
fitted using a power-law model with an Fe K emission line at 6.4 keV. We did
not find any statistically significant evidence for the existence of a
reflection component in the X-ray spectra of these two galaxies. The continuum
flux has decreased by a factor of approximately two during this period, in both
objects. However, the spectral index as well as the absorption column have
remained constant. We find weak evidence for the decrease of the normalization
of the Fe K emission line in a similar manner to the continuum in NGC7172. We
also report evidence for a broad Fe K confirming previous observations. In
contrast, in the case of ESO 103-G35 the line flux does not change while its
width remains unresolved.


title:
Evolution of globular cluster systems in three galaxies of the Fornax
  cluster

abstract:
  We studied and compared the radial profiles of globular clusters and of the
stellar bulge component in three galaxies of the Fornax cluster observed with
the WFPC2 of the HST. A careful comparative analysis of these distributions
confirms that stars are more concentrated toward the galactic centres than
globular clusters, in agreement with what was observed in many other galaxies.
If the observed difference is the result of evolution of the globular cluster
system sstarting from initial profiles similar to those of the halo--bulge
stellar components, a relevant fraction of their mass (74%, 47%, 52% for NGC
1379, NGC 1399 and NGC 1404, respectively) is disappeared in the inner regions,
likely contributing to the nuclear field population, local dynamics and high
energy phenomena in the primeval life of the galaxy. An indication in favour of
the evolutionary interpretation of the difference between the globular cluster
system and stellar bulge radial profiles is given by the positive correlation
we found between the value of the mass lost from the GCS and the central
galactic black hole mass in the set of seven galaxies for which these data are
available.


title: Galactic nuclear activity induced by globular cluster merging

abstract:
  The interpretation of the difference observed between the radial distribution
of globular clusters and that of halo-bulge stars in elliptical galaxies is
discussed in terms of evolution of their globular cluster systems. I present a
short summary of the evidence that dynamical evolution of globular cluster
systems is not only able to explain the flattening of their distribution toward
the galactic center, but also it may have played an important role on the
primordial activity of the parent galaxy.


title: Dust Absorption and Emission in Galaxies at High and Low Redshifts

abstract:
  This article reviews three related topics: the extragalactic background l
ight and its sources, evolution models for the dust absorption and emission in
galaxies, and empirical constraints on these transfer pr ocesses in nearby
starburst galaxies. It is intended that the material presented here will serve
as an introduction to this Joint Discussion.


title: Lepton asymmetry effect on neutrino oscillations and primordial He-4

abstract:
  We analyze the effects of lepton asymmetry on neutrino oscillations and on
cosmological nucleosynthesis with active-sterile oscillating neutrinos. It is
shown that small lepton asymmetries, L < 0.01, whose direct kinetic effect on
nucleosynthesis is negligible, still effect nucleosynthesis considerably
through their influence on oscillating neutrinos. Two different cases of lepton
asymmetry are discussed: an initially present and a dynamically generated in
oscillations. Dynamically generated in resonant oscillations asymmetry at small
mixing angles suppresses oscillations, hence, the nucleosynthesis bounds on
neutrino mass differences at small mixings are relaxed. Initially present
asymmetry may suppress or enhance oscillations. The enhancement is a result of
interchanging resonances between neutrino and antineutrino ensembles due to
resonance waves passing through the neutrino and antineutrino spectrum. Updated
nucleosynthesis bounds on neutrino oscillation parameters accounting for lepton
asymmetry are presented.


title: Global Evolution Models and the Extragalactic Background Light

abstract:
  This article outlines a method to interpret the extragalactic background
light in terms of the large-scale, average properties of galaxies, including
the comoving densities of stars and interstellar gas, metals, and dust. These
quantities are related by a series of coupled conservation-type equations
analogous to the equations of galactic chemical evolution. This approach
enables us to combine observations of the emission and absorption in galaxies
and thus to relate their average stellar and interstellar contents.
Applications of the method include predictions of the global history of star
formation from absorption-line observations and corrections to the cosmic UV
emissivity for absorption by dust.


title: Free floating planets in stellar clusters?

abstract:
  We have simulated encounters between planetary systems and single stars in
various clustered environments. This allows us to estimate the fraction of
systems liberated, the velocity distribution of the liberated planets, and the
separation and eccentricity distributions of the surviving bound systems. Our
results indicate that, for an initial distribution of orbits that is flat in
log space and extends out to 50AU, 50% of the available planets can be
liberated in a globular cluster, 25% in an open cluster, and less than 10% in a
young cluster. These fractions are reduced to 25%, 12% and 2% if the initial
population extends only to 20AU. Furthermore, these free-floating planets can
be retained for longer than a crossing time only in a massive globular cluster.
It is therefore difficult to see how planets, which by definition form in a
disc around a young star, could be subsequently liberated to form a significant
population of free floating substellar objects in a cluster.


title: Constraints from the damping tail

abstract:
  The detection of anisotropy in the cosmic microwave background on arcminute
scales by the Cosmic Background Imager (CBI) provides us with our first
measurement of the damping tail and closes one chapter in the CMB story. We now
have experimental verification for all of the features in the temperature
anisotropy spectrum predicted theoretically two decades ago. The CBI result
allows us to constrain both parameterized models based on the inflationary cold
dark matter (CDM) paradigm and to examine model independent constraints on the
matter content, the distance to last scattering and the thickness of the last
scattering surface. By providing a lower limit on the duration of recombination
it implies a lower limit on the polarization of the sub-degree scale anisotropy
which is close to current experimental upper limits.


title: Stellar Collisions and Blue Straggler Formation

abstract:
  We review recent 3D hydrodynamic calculations of stellar collisions using the
Smoothed Particle Hydrodynamics (SPH) method, and we discuss the implications
of the results for the formation and evolution of blue stragglers in globular
clusters. We also discuss the construction of simple analytic models for merger
remnants, approximating the mass loss, shock heating, mixing, and angular
momentum transport during a collision with simple algorithms that can be
calibrated using our 3D hydrodynamic results. The thermodynamic and chemical
composition profiles predicted by these simple models are compared with those
from our SPH simulations, demonstrating that our new models provide accurate
representations of true collisional merger remnants.


title:
Nuclear Reaction Rate Uncertainties and their effects on Nova
  Nucleosynthesis Modeling

abstract:
  The nucleosynthesis and other observable consequences of a nova outburst
depend sensitively on the details of the thermonuclear runaway which initiates
the outburst. One important source of uncertainty in our current models is the
nuclear reaction data used as input for the evolutionary calculations. We
present preliminary results of the first analyses of the impact on nova
nucleosynthesis of all reaction rate uncertainties considered simultaneously.


title: Extensive Air Shower Radio Detection: Recent Results and Outlook

abstract:
  A prototype system for detecting radio pulses associated with extensive
cosmic ray air showers is described. Sensitivity is compared with that in
previous experiments, and lessons are noted for future studies.


title:
Microstructure of the Local Interstellar Cloud and the Identification of
  the Hyades Cloud

abstract:
  We analyze high-resolution UV spectra of the Mg II h and k lines for 18
members of the Hyades Cluster to study inhomogeneity along these proximate
lines of sight. The observations were taken by the Space Telescope Imaging
Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). Three
distinct velocity components are observed. All 18 lines of sight show
absorption by the Local Interstellar Cloud (LIC), ten stars show absorption by
an additional cloud, which we name the Hyades Cloud, and one star exhibits a
third absorption component. The LIC absorption is observed at a lower radial
velocity than predicted by the LIC velocity vector derived by Lallement &
Bertin (1992) and Lallement et al. (1995), (v(predicted LIC) - v(observed LIC)
= 2.9 +/- 0.7 km/s), which may indicate a compression or deceleration at the
leading edge of the LIC. We propose an extention of the Hyades Cloud boundary
based on previous HST observations of other stars in the general vicinity of
the Hyades, as well as ground-based Ca II observations. We present our fits of
the interstellar parameters for each absorption component. The availability of
18 similar lines of sight provides an excellent opportunity to study the
inhomogeneity of the warm, partially ionized local interstellar medium (LISM).
We find that these structures are roughly homogeneous. The measured Mg II
column densities do not vary by more than a factor of 2 for angular separations
of < 8 degrees, which at the outer edge of the LIC correspond to physical
separations of < 0.6 pc.


title:
Thermal Infrared 3--5 $\mu$m Colors of Obscured and Unobscured Active
  Galactic Nuclei

abstract:
  Thermal infrared photometry in the $L$- and $M'$-band and $L - M'$ colors of
type-1 and type-2 active galactic nuclei (AGNs) are presented. After combining
our observations with photometric data at similar wavelengths taken from the
literature, we find that the excess of $L - M'$ colors of type-2 AGNs (37
sources, 50 data points) relative to type-1 AGNs (27 sources, 36 data points),
due to dust extinction, is statistically detectable, but very small. We next
investigate the $L - M'$ colors of type-2 AGNs by separating less dust-obscured
type-2 AGNs and highly dust-obscured type-2 AGNs. In both cases, the $L - M'$
colors are similar to the intrinsic $L - M'$ color of unobscured AGNs, and the
$L - M'$ color excess of the latter highly dust-obscured type-2 AGNs due to
dust extinction is much smaller than that expected from the Galactic dust
extinction curve. Contamination from starbursts and the time lag of flux
variation are unlikely to explain this small $L - M'$ color excess, which is
best explained if the dust extinction curve in the close vicinity of AGNs is
fairly flat at 3--5 $\mu$m as a result of a size increase of the absorbing dust
grains through coagulation.


title:
Studying the Galactic Bulge Through Spectroscopy of Microlensed Sources:
  II. Observations

abstract:
  The spectroscopy of microlensed sources towards the Galactic bulge provides a
unique opportunity to study (i) the kinematics of the Galactic bulge,
particularly its far-side, (ii) the effects of extinction on the microlensed
sources, and (iii) the contributions of the bulge and the disk lenses to the
microlensing optical depth. We present the results from such a spectroscopic
study of 17 microlensed sources carried out using the ESO Faint Object
Spectrograph (EFOSC) at the 3.6 m European Southern Observatory (ESO)
telescope. The spectra of the unlensed sources and Kurucz model spectra were
used as templates to derive the radial velocities and the extinctions of the
microlensed sources. It is shown that there is an extinction shift between the
microlensed population and the non-microlensed population but there is no
apparent correlation between the extinction and the radial velocity. This
extinction offset, in our best model, would imply that 65% of the events are
caused by self-lensing within the bulge. The sample needs to be increased to
about 100 sources to get a clear picture of the kinematics of the bulge.


title:
Faint X-ray sources resolved in the ASCA Galactic plane survey and their
  contribution to the Galactic ridge X-ray emission

abstract:
  The X-ray emission from the central region of the Galactic plane, |l|<45 deg
and |b|<0.4 deg, was studied in the 0.7-10 keV energy band with a spatial
resolution of ~3' with the ASCA observatory. We developed a new analysis method
for the ASCA data to resolve discrete sources from the extended Galactic ridge
X-ray emission (GRXE). We resolved 163 discrete sources with a flux down to
10^-12.5 ergs cm^-2 s^-1 and determined the intensity variations of the GRXE as
a function of the Galactic longitude with a spatial resolution of ~1 deg. The
longitudinal variation of the GRXE in the energy band above 4 keV shows a large
enhancement within |l|<30 deg. This suggests a strong enhancement of X-ray
emissivity inside the 4-kpc arms. Searches for identifications of the resolved
sources with cataloged X-ray sources and optical stars show that the 66% are
unidentified. Spectral analysis of each source shows that a large number of the
unidentified sources have hard X-ray spectra. We classified the sources into
several groups according to the spectra and analyzed the spectra summed within
each group. Possible X-ray origins of these sources are discussed based on the
grouping analysis. Also, we derived the LogN-LogS relations of the resolved
sources in the energy bands below and above 2 keV. The obtained LogN-LogS
relation of the Galactic X-ray sources above 2 keV is represented by a
power-law with an index of -0.79+/-0.07. This flat LogN-LogS relation suggests
that the spatial distribution of the sources should have an arm-like structure
in which the Solar system is included. The integrated surface brightness of the
resolved sources is about 10% of the total GRXE in both energy bands. The
approximately 90% of the emission remaining is still unresolved.


title: Mass-Losing Semiregular Variable Stars in Baade's Windows

abstract:
  By cross-correlating the results of two recent large-scale surveys, the
general properties of a well defined sample of semi-regular variable stars have
been determined. ISOGAL mid-infrared photometry and MACHO lightcurves are
assembled for approximately 300 stars in the Baade's Windows of low extinction
towards the Galactic bulge. These stars are mainly giants of late M spectral
type, evolving along the asymptotic giant branch (AGB). They are found to
possess a wide and continuous distribution of pulsation periods and to obey an
approximate log~period -- bolometric magnitude relation or set of such
relations.
  Approximate mass-loss rates in the range of 1e-8 to 5e-7 M_sun per year are
derived from ISOGAL mid-infrared photometry and models of stellar spectra
adjusted for the presence of optically-thin circumstellar silicate dust.
Mass-loss rates depend on luminosity and pulsation period. Some stars lose mass
as rapidly as short-period Miras but do not show Mira-like amplitudes. A period
of 70 days or longer is a necessary but not a sufficient condition for mass
loss to occur.
  For AGB stars in the mass-loss ranges that we observe, the functional
dependence of mass-loss rate on temperature and luminosity is found to be in
agreement with recent theoretical predictions. If we include our mass-loss
rates with a sample of extreme mass-losing AGB stars in the Large Magellanic
Cloud, we get the general result for AGB stars that mass-loss rate is
proportional to luminosity^{2.7}, valid for AGB stars with 10^{-8} to 10^{-4}
M_sun per year (Abridged).


title:
Faint field galaxies: an explanation of the faint blue excess using
  number evolution models

abstract:
  Pure luminosity evolution models for galaxies provide an unacceptable fit to
the redshifts and colors of faint galaxies. In this paper we demonstrate, using
HST morphological number counts derived both from the $I_{814}$-band of WFPC2
in the Medium Deep Survey (MDS) and the Hubble Deep Field (HDF) and from the
$H_{1.6}$-band of NICMOS, and ground-based spectroscopic data of the Hawaii
Deep Field and the Canada-France Redshift Survey, that number evolution is
necessary for galaxies, regardless of whether the cosmic geometry is flat,
open, or $\Lambda$-dominated. Furthermore, we show that the number evolution is
small at redshifts of z<1, but large at z>1, and that this conclusion is valid
for all the three cosmological models under consideration. If the universe is
open or $\Lambda$-dominated, the models, which are subject to the constraint of
the conservation of the comoving mass density of galaxies, naturally predict a
population of star-forming galaxies with the redshift distribution peaking at
$z=2\sim3$, which seems to be consistent with the recent findings from
Lyman-break photometric selection techniques. If the cosmological model is
flat, however, the conservation of the comoving mass density is invalid. Hence,
in order to account for the steep slope of B-band number counts at faint
magnitudes in the flat universe, such a star-forming galaxy population has to
be introduced ad hoc into the modelling alongside the merger assumption.


title: VLBI Observations of a Complete Sample of Radio Galaxies. 10 Years Later

abstract:
  A complete sample of 27 radio galaxies was selected from the B2 and 3CR
catalogs, in order to study their properties on the milliarcsecond scale. In
the Appendix of this paper we present new radio images for 12 of them. Thanks
to the present data, all the sources in this sample have been imaged at mas
resolution. We discuss the general results. In particular we stress the
evidence for high velocity jets in low power radio galaxies, we compare high
and low power sources, and discuss the source properties in the light of the
unified scheme models. We derive that the properties of parsec scale jets are
similar in sources with different total radio power and kpc scale morphology.
  From the core - total radio power correlation, we estimate that relativistic
jets with Lorentz factor $\gamma$ in the range 3 - 10 are present in high and
low power radio sources. We discuss also the possible existence of a two
velocity structure in the jets (fast spine and lower velocity external shear
layer).


title: Nebular Emission from Star-Forming Galaxies

abstract:
  We present a new model for computing consistently the line and continuum
emission from galaxies, based on a combination of recent population synthesis
and photoionization codes. We use effective parameters to describe the HII
regions and the diffuse gas ionized by single stellar generations in a galaxy
[...]. We calibrate the nebular properties of our model using the observed
[OIII]/Hbeta, [OII]/[OIII], [SII]/Halpha, and [NII]/[SII] ratios of a
representative sample of nearby spiral and irregular, starburst, and HII
galaxies. To compute whole (line plus continuum) spectral energy distributions,
we include the absorption by dust in the neutral interstellar medium (ISM)
using a recent simple prescription, which is consistent with observations of
nearby starburst galaxies. Our model enables us to interpret quantitatively the
observed optical spectra of galaxies in terms of stars, gas, and dust
parameters. We find that the range of ionized-gas properties spanned by nearby
galaxies implies factors of 3.5 and 14 variations in the Halpha and [OII]
luminosities produced per unit star formation rate (SFR). When accounting for
stellar Halpha absorption and absorption by dust in the neutral ISM, the actual
uncertainties in SFR estimates based on the emergent Halpha and [OII]
luminosities are as high as several decades. We derive new estimators of the
SFR, the gas-phase oxygen abundance, and the effective absorption optical depth
of the dust in galaxies. We show that, with the help of other lines such as
[OII], Hbeta, [OIII], [NII], or [SII], the uncertainties in SFR estimates based
on Halpha can be reduced to a factor of only 2-3, even if the Halpha line is
blended with the adjacent [NII] lines. Without Halpha, however, the SFR is
difficult to estimate from the [OII], Hbeta, and [OIII] lines. (abridged)


title:
Special relativistic spherically symmetric Lagrangean hydrodynamics from
  General Relativity

abstract:
  We re-derive hydrodynamical equations in General Relativity (GR) in the
comoving reference frame for spherical symmetry and obtain from them the
well-known but not explicitly derived Lagrangean equations in Special
Relativity (SR), that is, for the case of weak gravitational fields. Explicit
formulae are presented which relate General Relativistic independent variables,
Lagrangean mass coordinate and variables in the lab-frame. Conversion of one
set of variables into another requires knowing the solution to the set of
equations. These formulae allow one to translate the solution to the exact set
in General Relativity into the form in which Special Relativistic solutions are
usually obtained. This is applicable for comparison of SR-numerical simulations
of collapses, GRBs and Supernovae explosions with more precise GR-simulations.


title:
Derivation of preliminary IBIS response matrices with the INTEGRAL
  simulator

abstract:
  We have used the IBIS Simulator to produce preliminary response matrices for
the ISGRI and PICsIT detectors in order to help understanding their scientific
performances before the calibration results are available. The derived
matrices, in a format compatible with the XSPEC spectral analysis package, have
been tested by fitting simple models and then used to analyze simulations of
astrophysical sources with more complex spectra.