title:
A pulsational approach to near infrared and visual magnitudes of RR
  Lyrae stars

abstract:
  In this paper we present an improved theoretical scenario concerning near
infrared and visual magnitudes of RR Lyrae variables, as based on up-to-date
pulsating models. On this basis, we revisit the case of the prototype variable
RR Lyr, showing that the parallax inferred by this new pulsational approach
appears in close agreement with HST absolute parallax. Moreover, available K
and V measurements for field and cluster RR Lyrae variables with known
reddening and metal content are used to derive a relation connecting the K
absolute magnitude to period and metallicity, as well as a new calibration of
the M_V-[Fe/H] relation. The comparison between theoretical prescriptions and
observations suggests that RR Lyrae stars in the field and in Galactic Globular
Clusters should have quite similar evolutionary histories. The comparison
between theory and observations also discloses a general agreement that
supports the reliability of current pulsational scenario. On the contrary,
current empirical absolute magnitudes based on the Baade-Wesselink (BW) method
suggest relations with a zero-point that is fainter than predicted by pulsation
models, together with a milder metallicity dependence. However, preliminary
results based on a new calibration of the BW method provided by Cacciari et al.
(2000) for RR Cet and SW And appear in a much better agreement with the
pulsational predictions.


title: Neutron star cooling: Theoretical aspects and observational constraints

abstract:
  The cooling theory of isolated neutron stars is reviewed. The main cooling
regulators are discussed, first of all, operation of direct Urca process (or
similar processes in exotic phases of dense matter) and superfluidity in
stellar interiors. The prospects to constrain gross parameters of supranuclear
matter in neutron-star interiors by confronting cooling theory with
observations of isolated neutron stars are outlined. A related problem of
thermal states of transiently accreting neutron stars with deep crustal heating
of accreted matter is discussed in application to soft X-ray transients.


title:
Unusual CO Line Ratios and kinematics in the N83/N84 Region of the Small
  Magellanic Cloud

abstract:
  We present new CO 1-0 and 2-1 observations of the N83/N84 molecular cloud
complex in the south-east Wing of the Small Magellanic Cloud (SMC). While the
2-1/1-0 integrated line brightness ratio (in temperature units) is uniformly
0.9 throughout most of the complex, we find two distinct regions with unusually
high ratios 2-1/1-0 > 2. These regions are associated with the N84D nebula and
with the inside of the 50 pc expanding molecular shell N83. This shell is
spatially coincident with the NGC 456 stellar association and the HFPK2000-448
radio continuum/X-ray source tentatively classified as a supernova remnant. We
explore possible causes for the high ratios observed and conclude that the CO
emission probably arises from an ensemble of small (R~0.1 pc), warm (T~40 K)
clumps. Analysis of the CO shell parameters suggests that it is wind--driven
and has an age of slightly more than 2 million years. We have also used this
dataset to determine the CO-to-H2 conversion factor in the SMC, an especially
interesting measurement because of the low metallicity of this source (~1/9
solar). Surprisingly, after comparing the CO luminosities of clouds in N83/N84
with their virial masses, we find a CO-to-H2 conversion factor Xco only 1.9
times larger than what we obtain when applying the same algorithm to solar
metallicity clouds in the Milky Way and M 33. This result fits into the
emerging pattern that CO observations with high linear resolution suggest
nearly Galactic values of Xco in a wide range of environments.


title: Declination dependence of the cosmic-ray flux at extreme energies

abstract:
  We study the large-scale distribution of the arrival directions of the
highest energy cosmic rays observed by various experiments. Despite clearly
insufficient statistics, we find a deficit of cosmic rays at energies higher
than 10^{20} eV from a large part of the sky around the celestial North Pole.
We speculate on possible explanations of this feature.


title: Polarization of Herbig Ae/Be candidates and their environment

abstract:
  We present the V band polarization of 81 Herbig Ae/Be (HAeBe) candidates from
the Pico dos Dias Survey (PDS). A good estimate of the foreground polarization
was possible for most stars. A large number of objects shows intrinsic
polarization, which indicates that their circumstellar envelopes have some kind
of non-spherical symmetry. In this work, however, we study these data focusing
on their relation with the interstellar medium. Our data seem to indicate a
correlation between the position angle of the HAeBe star polarization and that
of the corresponding field stars. This may be an evidence that the ambient
interstellar magnetic field can play a role in the development of asymmetries
in the envelope of young stars of intermediate mass. The spatial distribution
of the sample relative to neighboring star forming regions is also studied.


title: COBE-DMR-Normalized Dark Energy Cosmogony

abstract:
  Likelihood analyses of the COBE-DMR sky maps are used to determine the
normalization of the inverse-power-law-potential scalar field dark energy
model. Predictions of the DMR-normalized model are compared to various
observations to constrain the allowed range of model parameters. Although the
derived constraints are restrictive, evolving dark energy density scalar field
models remain an observationally-viable alternative to the constant
cosmological constant model.


title:
Analysis of Clumps in Molecular Cloud Models: Mass Spectrum, Shapes,
  Alignment and Rotation

abstract:
  Observations reveal concentrations of molecular line emission on the sky,
called ``clumps,'' in dense, star-forming molecular clouds. These clumps are
believed to be the eventual sites of star formation. We study the
three-dimensional analogs of clumps using a set of self-consistent,
time-dependent numerical models of molecular clouds. The models follow the
decay of initially supersonic turbulence in an isothermal, self-gravitating,
magnetized fluid. We find the following. (1) Clumps are intrinsically triaxial.
This explains the observed deficit of clumps with a projected axis ratio near
unity, and the apparent prolateness of clumps. (2) Simulated clump axes are not
strongly aligned with the mean magnetic field within clumps, nor with the
large-scale mean fields. This is in agreement with observations. (3) The clump
mass spectrum has a high-mass slope that is consistent with the Salpeter value.
There is a low-mass break in the slope at $\sim 0.5 \msun$, although this may
depend on model parameters including numerical resolution. (4) The typical
specific spin angular momentum of clumps is $4 \times 10^{22} {\rm cm^2
s^{-1}}$. This is larger than the median specific angular momentum of binary
stars. Scaling arguments suggest that higher resolution simulations may soon be
able to resolve the scales at which the angular momentum of binary stars is
determined.


title: The Recent Star Formation History of the M31 Disk

abstract:
  The star formation history of the northern and southern M31 disk is measured
using samples of BV photometry for 4' X 4' regions taken from the KPNO/CTIO
Local Group Survey (Massey et al. 2001). The distances, mean reddening values,
and age distributions of the stars in these regions were measured using the
routines of Dolphin (1997, 2002). Independent measurements of overlapping
fields show that the results are stable for most samples. A slight distance
gradient is seen across the major axis of the southern disk, and a mean
distance of 24.47+/-0.03 is found by combining the results. Higher mean
reddening values follow the spiral structure. The stellar age distributions are
consistent with episodic star formation confined mainly to the gas-rich arm
regions. If these episodes were caused by propagating density waves, the waves
did not cause significant star formation episodes in the gas-poor interarm
regions. Combination of all of the results provides the total star formation
rate for 1.4 square degrees of the M31 disk for six epochs. These results
suggest that star formation in the disk declined by ~50% from ~250 to ~50 Myr
ago. The lowest star formation rate occurred ~25 Myr ago followed by a ~20%
increase to the present. The mean star formation rate for this large portion of
M31 over the past 60 Myr is 0.63+/-0.07 solar masses per year, suggesting a
total mean rate for the disk of ~1 solar masses per year.


title: Linear Polarization Observations of Water Masers in W3 IRS5

abstract:
  We present a magnetic field mapping of water maser clouds in the star-forming
region W3 IRS5, which has been made on the basis of the linear polarization
VLBI observation. Using the Very Long Baseline Array (VLBA) at 22.2 GHz, 16 of
61 detected water masers were found to be linearly polarized with polarization
degrees up to 13%. Although 10 polarized features were widely distributed in
the whole W3 IRS5 water maser region, they had similar position angles of the
magnetic field vectors (~75 deg from the north). The magnetic field vectors are
roughly perpendicular to the spatial alignments of the maser features. They are
consistent with the hourglass model of the magnetic field, which was previously
proposed to explain the magnetic field in the whole W3 Main region (r~0.1 pc).
They are, on the other hand, not aligned to the directions of maser feature
proper motions observed previously. This implies that the W3 IRS5 magnetic
field was controlled by a collapse of the W3 Main molecular cloud rather than
the outflow originated from W3 IRS5.


title: Djehuty, a Code for Modeling Stars in Three Dimensions

abstract:
  Current practice in stellar evolution is to employ one-dimensional
calculations that quantitatively apply only to a minority of the observed stars
(single non-rotating stars, or well detached binaries). Even in these systems,
astrophysicists are dependent on approximations to handle complex
three-dimensional processes like convection. Understanding the structure of
binary stars, like those that lead to the Type Ia supernovae used to measure
the expansion of the universe, are grossly non-spherical and await a 3D
treatment.
  To approach very large problems like multi-dimensional modeling of stars, the
Lawrence Livermore National Laboratory has invested in massively parallel
computers and invested even more in developing the algorithms to utilize them
on complex physics problems. We have leveraged skills from across the lab to
develop a 3D stellar evolution code, Djehuty (after the Egyptian god for
writing and calculation) that operates efficiently on platforms with thousands
of nodes, with the best available physical data (opacities, EOS, etc.). Djehuty
has incorporated all basic physics for modeling stars including an accurate
equation of state, radiation transport by diffusion, thermonuclear reaction
rates, and hydrodynamics, and we have begun testing it in a number of
applications.


title: Is High-Velocity Cloud Complex C Associated with the Galactic Warp?

abstract:
  We test the hypothesis that High-Velocity gas cloud Complex C is actually a
high-latitude spiral arm extension in the direction of the Galactic warp, as
opposed to the standard interpretation - that of a once extragalactic, but now
infalling, gas cloud. A parallel Tree N-body code was employed to simulate the
tidal interaction of a satellite perturber with the Milky Way. We find that a
model incorporating a perturber of the mass of the Large Magellanic Cloud on a
south-to-north polar orbit, crossing the disk at ~15 kpc, does yield a high-
velocity, high-latitude, extension consistent with the spatial, kinematical and
column density properties of Complex C. Unless this massive satellite remains
undiscovered because of either a fortuitous alignment with the Galactic bulge
(feasible within the framework of the model), or the lack of any associated
baryonic component, we conclude that this alternative interpretation appears
unlikely.


title: HII regions in the spiral galaxy NGC 3389

abstract:
  CCD observations in V, I and H$_\alpha$ for NGC 3389 are used to present
photometry of 61 HII regions. Their $\alpha$ and $\delta$ positions, diameters
and their absolute luminosities have been determined. The luminosity and size
distribution functions of the HII regions in NGC 3389 are discussed.


title:
Cluster abundance evolution and the Sunyaev-Zeldovich effect in various
  cosmological models

abstract:
  The redshift dependence of the observed cluster abundance due to the
Sunyaev-Zeldovich Effect (SZE) is studied in various cosmological models
including flat and open homogeneous (CDM) models and an inhomogeneous model
with a large-scale local void. The Press-Schechter formalism is used to derive
the abundance at epochs 0 < z < 2 and the cluster mass limit Mlim is given from
a flux limit for SZE. It is shown that SZE is useful for constraining the
cosmological model parameters, and the abundance in the inhomogeneous model may
be comparable with that in the low-density homogeneous models. The significance
of relative difference of abundances in the various models is discussed.


title:
On The Spectrum and Spectropolarimetry of Type Ic Hypernova SN
  2003dh/GRB 030329

abstract:
  Spectroscopic and spectropolarimetric observations of SN 2003dh/GRB 030329
obtained in 2003 May using the Subaru 8.2 m telescope are presented. The
properties of the SN are investigated through a comparison with spectra of the
Type Ic hypernovae SNe 1997ef and 1998bw. (Hypernovae being a tentatively
defined class of SNe with very broad absorption features: these features
suggest a large velocity of the ejected material and possibly a large explosion
kinetic energy.) Comparison with spectra of other hypernovae shows that the
spectrum of SN 2003dh obtained on 2003 May 8 and 9, i.e., 34-35 rest-frame days
after the GRB (for z=0.1685), are similar to those of SN 1997ef obtained ~34-42
days after the fiducial time of explosion of that SN. The match with SN 1998bw
spectra is not as good (at rest 7300-8000 A, but again spectra obtained ~33-43
days after GRB 980425 are preferred. This indicates that the SN may have
intermediate properties between SNe 1997ef and 1998bw. Based on the analogy
with the other hypernovae, the time of explosion of SN 2003dh is then
constrained to be between -8 and +2 days of the GRB. The Si and O P-Cygni lines
of SN 2003dh seem comparable to those of SN 1997ef, which suggests that the
ejected mass in SN 2003dh may match that in SN 1997ef. Polarization was
marginally detected at optical wavelengths. This is consistent with
measurements of the late afterglow, implying that it mostly originated in the
interstellar medium of the host galaxy.


title:
A spectral survey of the Star Forming Core of the Orion Nebula from 455
  -- 507 GHz

abstract:
  The results of a submillimetre wavelength spectral line survey between 455.1
-- 507.4 GHz of the Orion-KL hot cloud core are reported. A total of 254 lines
were detected to a main beam brightness temperature sensitivity ~ 1 - 3 K. The
detected lines are identified as being associated with 30 different molecular
species or their isotopomeric variants. The strongest line detected was the J =
4-3 transition of the CO molecule. Apart from abundant diatomic rotors such as
CO and CS, the spectrum is dominated by SO, SO_2 and CH_3OH and large organic
molecules such as (CH_3)_2O, CH$_3CN, C_2H_3CN, C_2H_5CN and HCOOCH_3 which
make up ~ 72% of the total number of lines; unidentified lines ~ 13%; and other
lines the remaining ~ 15% of the total. Rotational temperatures and column
densities derived using standard rotation diagram analysis techniques were
found to range from 70 - 300 K, and 10^14 - 10^17 cm^2 respectively.
  Accepted by Astronomy & Astrophysics 22 May 2003


title: Chandra Observations of the Central Region of Abell 3112

abstract:
  We present the results of a {\it Chandra} observation of the central region
of Abell 3112. This cluster has a powerful radio source in the center and was
believed to have a strong cooling flow. The X-ray image shows that the
intracluster medium (ICM) is distributed smoothly on large scales, but has
significant deviations from a simple concentric elliptical isophotal model near
the center. Regions of excess emission appear to surround two lobe-like
radio-emitting regions. This structure probably indicates that hot X-ray gas
and radio lobes are interacting. From an analysis of the X-ray spectra in
annuli, we found clear evidence for a temperature decrease and abundance
increase toward the center. The X-ray spectrum of the central region is
consistent with a single-temperature thermal plasma model. The contribution of
X-ray emission from a multiphase cooling flow component with gas cooling to
very low temperatures locally is limited to less than 10% of the total
emission. However, the whole cluster spectrum indicates that the ICM is cooling
significantly as a whole, but in only a limited temperature range ($\geq 2$
keV). Inside the cooling radius, the conduction timescales based on the Spitzer
conductivity are shorter than the cooling timescales. We detect an X-ray point
source in the cluster center which is coincident with the optical nucleus of
the central cD galaxy and the core of the associated radio source. The X-ray
spectrum of the central point source can be fit by a 1.3 keV thermal plasma and
a power-law component whose photon index is 1.9. The thermal component is
probably plasma associated with the cD galaxy. We attribute the power-law
component to the central AGN.


title:
The Effect of Non-Thermal Protons on the High Energy Spectra of Black
  Hole Binaries

abstract:
  In the inner regions of an accretion disk around a black hole, the presence
of non-thermal protons would via p-p collisions produce electrons, positrons
and $\gamma$-rays. For such a scenario, the steady state electron-positron
distribution is computed taking into account Compton cooling, $e^{-} e^{+}$
pair production (due to $\gamma-\gamma$ interactions) and pair annihilation.
The resultant spectra has a broad feature around $1 - 10$ MeV which may be
tested with observations by INTEGRAL and GLAST. Using the available OSSE data
for the black hole system, GRS 1915+115 we illustrate that an upper limit on
the non-thermal proton fraction can be obtained, which may put constraints on
the acceleration process active in this system.


title:
An experimental foundation for electromagnetic shower formation in the
  geomagnetic field

abstract:
  At very high energies the Earth magnetic field, although in many other
connections conside red rather weak, acts as a strong field on photons and
leptons. This paper discusses the i ntimate connection between this effect and
the corresponding `strong field effects' observ ed at accessible accelerator
energies in aligned single crystals. As such, these effects c onstitute an
experimental verification of the theoretical basis used for simulations of th e
development of electromagnetic showers in magnetic fields, in particular the
geomagnetic field. A short discussion of more general aspects of the shower
development in the fields present at different distance scales is included.


title:
The Chemical Composition of Two Supergiants in the Dwarf Irregular
  Galaxy WLM

abstract:
  [Abridged] The chemical composition of two stars in WLM has been determined
from high quality UVES data obtained at the VLT UT2 (program 65.N-0375). The
model atmospheres analysis shows that they have the same metallicity, [Fe/H] =
-0.38 +/-0.20, and [Mg/Fe] = -0.24 +/-0.16. This result suggests that the
[alpha(Mg)/Fe] ratio in WLM may be suppressed relative to solar abundances
(also supported by differential abundances relative to similar stars in NGC6822
and the SMC). The absolute Mg abundance, [Mg/H] = -0.62 is high relative to
what is expected from the nebulae though, where two independent spectroscopic
analyses of the HII regions in WLM yield [O/H] = -0.89. Intriguingly, the
oxygen abundance determined from the OI 6158 feature in one WLM star is [O/H] =
-0.21 +/-0.10, corresponding to five times higher than the nebular oxygen
abundance. This is the first time that a significant difference between young
stellar and nebular oxygen abundances has been found, and presently, there is
no simple explanation for this difference. If the stellar abundances reflect
the true composition of WLM, then this galaxy lies well above the
metallicity-luminosity relationship for dwarf irregular galaxies. It also
suggests that WLM is more chemically evolved than currently interpreted from
its color-magnitude diagram.


title: Constraining the Cosmic Star Formation Rate with the MeV Background

abstract:
  The Cosmic Gamma-ray Background (CGB) in the MeV regime has been measured
with COMPTEL and SMM. The origin of the CGB in this energy regime is believed
to be dominated by gamma-rays from Type Ia supernovae. We calculate the CGB
spectrum within the framework of FRW cosmology as a function of the cosmic star
formation rate, SFR(z). Several estimates of the SFR(z) have been reported
since the pioneering work of Madau et al. Here we discuss observational
constraints on SFR(z) derived from models of the CGB. In particular, we
consider the SFR obtained from Gamma-Ray Burst observations, which increases
dramatically with redshift beyond z ~ 1 in contrast to most estimates which
saturate or show a mild increase with redshift. Gamma-ray bursts may be the
most powerful tracers of star formation in the early universe and thus provide
signposts of the initial epoch of element synthesis. The star formation rate
implied by GRB statistics results in a gamma-ray background that matches the
observations more closely than that inferred from other tracers of star
formation. This may provide some support for the GRB/SFR-paradigm, which in
turn promises a powerful diagnostic of star formation, and thus cosmic chemical
evolution, from the era of Population III stars to the present.


title: The origin of peculiar jet-torus structure in the Crab nebula

abstract:
  Recent discoveries of the intriguing ``jet-torus'' structure in the Crab
Nebula and other pulsar nebulae prompted calls for re-examining of their
theory. The most radical proposals involve abolishing of the MHD approximation
altogether and developing of purely electromagnetic models. However, the
classical MHD models of the Crab Nebula were hampered by the assumption of
spherical symmetry made in order to render the flow equations easily
integrable. The impressive progress in computational relativistic
magnetohydrodynamics in recent years has made it possible to study the Crab
nebula via numerical simulations without making such a drastic simplification
of the problem. In this letter we present the results of the first study of
such kind. They show that the jet-torus pattern can be explained within MHD
approximation when anisotropy of pulsar winds is taken into account. They also
indicate that the flow in the nebula is likely to be much more intricate than
it has been widely believed.


title: Black hole masses and the Fundamental Plane of BL Lac objects

abstract:
  We report on measurements of the stellar velocity dispersion (sigma) from the
optical spectra of the host galaxies of four BL Lac objects. Together with our
earlier results on seven BL Lac objects (Falomo et al. 2002), and with the
previously derived photometrical and structural properties, these data are used
to construct the Fundamental Plane (FP) of the BL Lac hosts. We find that the
BL Lacs follow the same FP as low redshift radio galaxies and inactive luminous
ellipticals, in agreement with similar results presented by Barth et al.
(2003). This indicates that the photometrical, structural and kinematical
properties of the host galaxies of BL Lacs are indistinguishable from those of
inactive massive ellipticals. Using the correlation between black hole mass
(M_BH) and sigma in nearby elliptical galaxies, we derive the masses of the
central black hole in BL Lacs. These masses, in the range of 6 x 10^7 to 9 x
10^8 M_o, are consistent with the values derived from the bulge luminosity and
appear to be linearly correlated with the mass of the galaxies (M_BH} ~0.001 x
M_bulge).


title: Goodness-of-Fit Tests to study the Gaussianity of the MAXIMA data

abstract:
  Goodness-of-Fit tests, including Smooth ones, are introduced and applied to
detect non-Gaussianity in Cosmic Microwave Background simulations. We study the
power of three different tests: the Shapiro-Francia test (1972), the
uncategorised smooth test developed by Rayner and Best(1990) and the Neyman's
Smooth Goodness-of-fit test for composite hypotheses (Thomas and Pierce 1979).
The Smooth Goodness-of-Fit tests are designed to be sensitive to the presence
of ``smooth'' deviations from a given distribution. We study the power of these
tests based on the discrimination between Gaussian and non-Gaussian
simulations. Non-Gaussian cases are simulated using the Edgeworth expansion and
assuming pixel-to-pixel independence. Results show these tests behave similarly
and are more powerful than tests directly based on cumulants of order 3, 4, 5
and 6. We have applied these tests to the released MAXIMA data. The applied
tests are built to be powerful against detecting deviations from univariate
Gaussianity. The Cholesky matrix corresponding to signal (based on an assumed
cosmological model) plus noise is used to decorrelate the observations previous
to the analysis. Results indicate that the MAXIMA data are compatible with
Gaussianity.


title:
Spectroscopic and photometric studies of low-metallicity star-forming
  dwarf galaxies. I. SBS 1129+576

abstract:
  Spectroscopy and V,I CCD photometry of the dwarf irregular galaxy SBS
1129+576 are presented for the first time. The CCD images reveal a chain of
compact H II regions within the elongated low-surface-brightness (LSB)
component of the galaxy. Star formation takes place mainly in two
high-surface-brightness H II regions. The mean (V-I) colour of the LSB
component in the surface brightness interval between 23 and 26 mag/sq.arcsec is
relatively blue ~0.56+/-0.03 mag, as compared to the (V-I)~0.9-1.0 for the
majority of known dwarf irregular and blue compact dwarf (BCD) galaxies.
Spectroscopy shows that the galaxy is among the most metal-deficient galaxies
with an oxygen abundance 12+log(O/H)= 7.36+/-0.10 in the brightest H II region
and 7.48+/-0.12 in the second brightest H II region, or 1/36 and 1/28 of the
solar value, respectively. Hbeta and Halpha emission lines and Hdelta and
Hgamma absorption lines are detected in a large part of the LSB component. We
use two extinction-insensitive methods based on the equivalent widths of (1)
emission and (2) absorption Balmer lines to put constraints on the age of the
stellar populations in the galaxy. In addition, we use two extinction-dependent
methods based on (3) the spectral energy distribution (SED) and (4) the (V-I)
colour. The observed properties of the LSB component can be reproduced by a
stellar population forming continuously since 10 Gyr ago, provided that the
star formation rate has increased during the last 100 Myr by a factor of 6 to
50 and no extinction is present. However, the observational properties of the
LSB component can be reproduced equally well by continuous star formation which
started not earlier than 100 Myr ago and stopped at 5 Myr, if some extinction
is assumed.(Abridged)


title:
Spectroscopic and photometric studies of low-metallicity star-forming
  dwarf galaxies. II. HS 1442+4250

abstract:
  We present broad-band V and I imaging and long-slit spectroscopy in the
optical range 3600-7500A of the dwarf irregular galaxy HS 1442+4250. The oxygen
abundance 12+log(O/H)=7.63+/-0.02 (Z=Zsun/19) in the brightest H II region of
HS 1442+4250 places the galaxy among the most metal-deficient emission-line
galaxies. The low metallicity and blue colour (V-I)~0.4 mag of the
low-surface-brightness (LSB) component make HS 1442+4250 a likely rare young
dwarf galaxy candidate. We use four methods to estimate the stellar population
age in the LSB component of HS 1442+4250. Different star formation histories
are considered. The equivalent widths of hydrogen Halpha and Hbeta emission
lines, and of hydrogen Hgamma and Hdelta absorption lines, the spectral energy
distribution and the observed (V-I) colours of the LSB regions are reproduced
quite well by models with only young and intermediate-age stellar populations.
By contrast, the observational data cannot be reproduced by a stellar
population formed continuously with a constant star formation rate in the age
range from 0 to > 2 Gyr. While a faint old stellar population in HS 1442+4250
with an age > 2 Gyr is not excluded, we find no evidence for such a population
from the present data.


title:
Spectroscopic and photometric studies of low-metallicity star-forming
  dwarf galaxies. III. SBS 1415+437

abstract:
  We present a detailed optical spectroscopic and B,V,I,Halpha photometric
study of the metal-deficient cometary blue compact dwarf (BCD) galaxy SBS
1415+437. We derive an oxygen abundance 12+log(O/H)=7.61+/-0.01 and 7.62+/-0.03
(Z =Zsun/20) in the two brightest H II regions, among the lowest in BCDs. The
helium mass fractions in these regions are Y=0.246+/-0.003 and 0.243+/-0.010.
Four techniques based on the equivalent widths of the hydrogen emission and
absorption lines, the spectral energy distribution and the colours of the
galaxy are used to put constraints on the age of the stellar population in the
low-surface-brightness (LSB) component of the galaxy, assuming two limiting
cases of star formation (SF), the case of an instantaneous burst and that of a
continuous SF with a constant or a variable star formation rate (SFR). The
spectroscopic and photometric data for different regions of the LSB component
are well reproduced by a young stellar population with an age t<250 Myr,
assuming a small extinction in the range A(V)= 0-0.6 mag. Assuming no
extinction, we find that the upper limit for the mass of the old stellar
population, formed between 2.5 Gyr and 10 Gyr, is not greater than ~(1/20 - 1)
of that of the stellar population formed during the last ~250 Myr. Depending on
the region considered, this also implies that the SFR in the most recent SF
period must be 20 to 1000 times greater than the SFR at ages > 2.5 Gyr. We
compare the photometric and spectroscopic properties of SBS 1415+437 with those
of a sample of 26 low-metallicity dwarf irregular and BCD galaxies. We show
that there is a clear trend for the stellar LSB component of lower-metallicity
galaxies to be bluer. This trend cannot be explained only by metallicity
effects. There must be also a change in the age of the stellar populations.


title: A Re-evaluation of the Super Li-rich Star in NGC 6633

abstract:
  We present a new abundance analysis of the super Li-rich star J37 and a
comparison star in NGC 6633. We confirm the result of Deliyannis et al. that
J37 has a Li abundance well above the meteoritic value, and we also confirm
that Al, S, Si, Ca, Fe and Ni are super-solar, and C is sub-solar. We
additionally find that Na, Sc, Ti are super-solar, while O is sub-solar. The
abundance pattern of metals in J37 is generally consistent with the bulk
composition of the Earth. We propose that accretion of circumstellar matter is
the best explanation for these abundance anomalies, although we cannot rule out
a secondary contribution from diffusion.


title:
An AGN Sample with High X-ray-to-optical Flux Ratio from RASS II.Optical
  Emission Line Properties of Seyfert 1 Type AGN

abstract:
  This work studies the optical emission line properties of a sample of 155
low-redshift bright X-ray selected ROSAT Seyfert~1 type AGN for which adequate
signal-to-noise ratio spectroscopic observations are available. We measured
emission line properties by performing multi-component fits to the emission
line profiles, covering the effect of blended iron emission. We also obtained
continuum parameters, including 250eV X-ray luminosities derived from the ROSAT
database. In addition, the measured properties are gathered for a correlation
analysis, which confirms the well-known relations between the strengths of
Fe~II, [O III] emission and the X-ray slope. We also detect striking
correlations between H$\beta$ redshift (or blueshift), flux ratios of Fe `II to
H$\beta$ broad component and [O III] to H$\beta$ narrow component. These trends
are most likely driven by the Eddington ratio.


title: Star Formation in Massive Protoclusters in the Monoceros OB1 Dark Cloud

abstract:
  We present far-infrared, submillimetre, and millimetre observations of bright
IRAS sources and outflows that are associated with massive CS clumps in the
Monoceros OB1 Dark Cloud. Individual star-forming cores are identified within
each clump. We show that combining submillimetre maps, obtained with SCUBA on
the JCMT, with HIRES-processed and modelled IRAS data is a powerful technique
that can be used to place better limits on individual source contributions to
the far-infrared flux in clustered regions. Three previously categorized "Class
I objects" are shown to consist of multiple sources in different evolutionary
stages. In each case, the IRAS point source dominates the flux at 12 and 25
microns. In two cases, the IRAS point source is not evident at submillimetre
wavelengths. The submillimetre sources contribute significantly to the 60 and
100 micron fluxes, dominating the flux in the 100 micron waveband. Using fluxes
derived from our technique, we present the spectral energy distribution and
physical parameters for an intermediate-mass Class 0 object in one of the
regions. Our new CO J=2-1 outflow maps of the three regions studied indicate
complex morphology suggestive of multiple driving sources. We discuss the
possible implications of our results for published correlations between outflow
momentum deposition rates and "source" luminosities, and for using these
derived properties to estimate the ratio of mass ejection rates to mass
accretion rates onto protostars.


title:
The Effects of Massive Substructures on Image Multiplicities in
  Gravitati onal Lenses

abstract:
  Surveys for gravitational lens systems have typically found a significantly
larger fraction of lenses with four (or more) images than are predicted by
standard ellipsoidal lens models (50% versus 25-30%). We show that including
the effects of smaller satellite galaxies, with an abundance normalized by the
observations, significantly increases the expected number of systems with more
than two images and largely explains the discrepancy. The effect is dominated
by satellites with ~20% the luminosity of the primary lens, in rough agreement
with the typical luminosities of the observed satellites. We find that the lens
systems with satellites cannot, however, be dropped from estimates of the
cosmological model based on gravitational lens statistics without significantly
biasing the results.


title: On the diversity of short GRBs

abstract:
  Hydrodynamical simulations of the last inspiral stages and the final
coalescence of a double neutron star system are used to investigate the power
of the neutrino-driven wind, the energy and momentum of the fireball produced
via $\nu \bar{\nu}$-annihilation, and the intensity and character of their
interaction. It is argued that the outflow that derives from the debris will
have enough pressure to collimate the relativistic fireball that it surrounds.
The low luminosity relativistic jet will then appear brighter to an observer
within the beam although most of the energy of the event is in the unseen, less
collimated and slower wind. This model leads to a simple physical
interpretation of the isotropic luminosities implied for short GRBs at
cosmological distances. A wide variety of burst phenomenology could be
attributable to the dependence of the neutrino luminosity on the initial mass
of the double NS binary.


title: Formation Scenarios for Intermediate-Mass Black Holes

abstract:
  Black holes with hundreds to thousands of solar masses are more massive than
can be formed from a single star in the current universe, yet the best
candidates for these objects are not located in gas-rich environments where
gradual accretion could build up the mass. Three main formation scenarios have
been suggested in the literature: that intermediate-mass black holes are the
remnants of the first, metal-poor, stars; that they result from direct
collisions in young stellar clusters; or that they are produced by gradual
interactions and mergers of compact objects in old dense clusters. We discuss
each of these in turn and speculate on future observations that may help
sharpen our understanding of the formation of intermediate-mass black holes.


title: Cluster Lensing of QSOs as a Probe of LCDM and Dark Energy Cosmologies

abstract:
  Wide-separation lensed QSOs measure the mass function and evolution of
massive galaxy clusters, in a similar way to the cluster mass function deduced
from X-ray-selected samples or statistical measurements of the
Sunyaev-Zeldovich effect. We compute probabilities of strong lensing of QSOs by
galaxy clusters in dark energy cosmologies using semianalytical modelling and
explore the sensitivity of the method to various input parameters and
assumptions. We highlight the importance of considering both the variation of
halo properties with mass, redshift and cosmology and the effect of cosmic
scatter in halo concentration. We then investigate the extent to which
observational surveys for wide-separation lensed QSOs may be used to measure
cosmological parameters such as the fractional matter density Omega_M, the rms
linear density fluctuation in spheres of 8 Mpc/h, sigma_8, and the dark energy
equation of state parameter w. We find that wide-separation lensed QSOs can
measure sigma_8 and Omega_M in an equivalent manner to other methods such as
cluster abundance studies and cosmic shear measurements. In assessing whether
lensing statistics can distinguish between values of w, we conclude that at
present the uncertainty in the calibration of sigma_8 in quintessence models
dominates the conclusions reached. Nonetheless, lensing searches based on
current QSO surveys such as the Two-degree Field and the Sloan Digital Sky
Survey with 10^4-10^5 QSOs should detect systems with angular separations
greater than 5'' and hence can provide an important test of the standard
cosmological model that is complementary to measurements of cosmic microwave
background anisotropies.


title: Mass-to-Light Ratios of 2dF Galaxies

abstract:
  We compute M_260, the dynamical mass interior to a radius of 260 kpc/h, for a
set of 809 isolated host galaxies in the 100k data release of the 2dF Galaxy
Redshift Survey. The hosts are surrounded by 1556 satellite galaxies, as
defined by a set of specific selection criteria. Our mass estimator and
host/satellite selection criteria are taken from those used by the Sloan
Digital Sky Survey (SDSS) collaboration for an analysis of M_260 for SDSS
galaxies and, overall, our results compare well with theirs. For L > 2L* we
find M_260/L = (193 +/- 14)h Msun/Lsun, with a tendency for hosts with L < 2L*
to have a somewhat higher M/L. We also investigate M/L seperately for bright
galaxies with ellipitical, S0, and spiral morphologies. There are 159 hosts in
the elliptical/S0 sample, for which we find M_260/L = (271 +/- 26) h Msun/Lsun
for galaxies with L > 2L*, and a weak tendency for intrinsically fainter
galaxies to have a somewhat higher M/L. In stark contrast to this, we find the
line of sight velocity dispersion for the 243 spiral hosts to be independent of
the host galaxy luminosity, yielding a value of sigma_v = 189 +/- 19 km/s. Thus
for the spiral hosts, M_260/L is proportional to L^{-1.0 +/- 0.2}, and we find
M_260/L for a 2L* spiral is of order 200 h Msun/Lsun.


title:
The Response of Model and Astrophysical Thermonuclear Flames to
  Curvature and Stretch

abstract:
  Critically understanding the `standard candle'-like behavior of Type Ia
supernovae requires understanding their explosion mechanism. One family of
models for Type Ia Supernovae begins with a deflagration in a Carbon-Oxygen
white dwarf which greatly accelerates through wrinkling and flame
instabilities. While the planar speed and behavior of astrophysically-relevant
flames is increasingly well understood, more complex behavior, such as the
flame's response to stretch and curvature, has not been extensively explored in
the astrophysical literature; this behavior can greatly enhance or suppress
instabilities and local flame-wrinkling, which in turn can increase or decrease
the bulk burning rate. In this paper, we explore the effects of curvature on
both nuclear flames and simpler model flames to understand the effect of
curvature on the flame structure and speed.


title: The jets of the Vela pulsar

abstract:
  Chandra observations of the Vela pulsar-wind nebula (PWN) have revealed a jet
in the direction of the pulsar's proper motion, and a counter-jet in the
opposite direction, embedded in diffuse nebular emission. The jet consists of a
bright, 8''-long inner jet, between the pulsar and the outer arc, and a dim,
curved outer jet that extends up to 100'' in approximately the same direction.
  From the analysis of thirteen Chandra observations spread over about 2.5
years we found that this outer jet shows particularly strong variability,
changing its shape and brightness. We observed bright blobs in the outer jet
moving away from the pulsar with apparent speeds (0.3-0.6)c and fading on
time-scales of days to weeks. The spectrum of the outer jet fits a power-law
model with a photon index of 1.3\pm0.1. The X-ray emission of the outer jet can
be interpreted as synchrotron radiation of ultrarelativistic
electrons/positrons. This interpretation allows one to estimate the magnetic
field, ~100 microGauss, maximum energy of X-ray emitting electrons, ~2\times
10^{14} eV, and energy injection rate, ~8\times 10^{33} erg/s, for the outer
jet. In the summed PWN image we see a dim, 2'-long outer counter-jet, which
also shows a power-law spectrum with photon ined of 1.2-1.5. Southwest of the
jet/counter-jet an extended region of diffuse emission is seen. Relativistic
particles responsible for this radiation are apparently supplied by the outer
jet.


title: Turbulent Energy Transport in Nonradiative Accretion Flows

abstract:
  Just as correlations between fluctuating radial and azimuthal velocities
produce a coherent stress contributing to the angular momentum transport in
turbulent accretion disks, correlations in the velocity and temperature
fluctuations produce a coherent energy flux. This nonadvective energy flux is
always of secondary importance in thin radiative disks, but cannot be neglected
in nonradiative flows, in which it completes the mean field description of
turbulence. It is, nevertheless, generally ignored in accretion flow theory,
with the exception of models explicitly driven by thermal convection, where it
is modeled phenomenologically. This flux embodies both turbulent thermal
convection as well as wave transport, and its presence is essential for a
proper formulation of energy conservation, whether convection is present or
not. The sign of the thermal flux is likely to be outward in real systems, but
the restrictive assumptions used in numerical simulations may lead to inward
thermal transport, in which case qualitatively new effects may be exhibited. We
find, for example, that a static solution would require inward, not outward,
thermal transport. Even if it were present, thermal convection would be
unlikely to stifle accretion, but would simply add to the outward rotational
energy flux that must already be present.


title: Accretion Models for Young Neutron Stars

abstract:
  Interaction with possible fallback material, along with the magnetic fields
and rotation rates at birth should determine the fates and categories of young
neutron stars. This paper addresses some issues related to pure or hybrid
accretion models for explaining the properties of young neutron stars.


title: Evidence for an Extended SZ Effect in WMAP Data

abstract:
  We have cross-correlated the WMAP data with several surveys of extragalactic
sources and find evidence for temperature decrements associated with galaxy
clusters and groups detected in the APM Galaxy Survey survey and the ACO
catalogue. We interpret this as evidence for the thermal Sunyaev-Zeldovich (SZ)
effect from the clusters. Most interestingly, the signal may extend to ~1 deg
around both groups and clusters and we suggest that this may be due to hot
`supercluster' gas. We have further cross-correlated the WMAP data with
clusters identified in the 2MASS galaxy catalogue and also find evidence for
temperature decrements there. From the APM group data we estimate the mean
Compton parameter as y(z<0.2)=7x10^(-7). We have further estimated the gas mass
associated with the galaxy group and cluster haloes. Assuming temperatures of 5
keV for ACO clusters and 1 keV for APM groups and clusters, we derive average
gas masses. Using the space density of APM groups we then estimate Omega_gas.
For an SZ extent of theta_max=20', kT=1 keV and h=0.7, this value of
Omega_gas=0.04 is consistent with the standard value of Omega_baryon=0.044 but
if the indications we have found for a more extended SZ effect out to theta=60'
are confirmed, then higher values of Omega_gas will be implied. Finally, the
contribution to the WMAP temperature power spectrum from the extended SZ effect
around the z<0.2 APM+ACO groups and clusters is 1-2 orders of magnitude lower
than the l=220 first acoustic peak. But if a similar SZ effect arises from more
distant clusters then this contribution could increase by a factor >10 and then
could seriously affect the WMAP cosmological fits.


title:
Cosmic Microwave Background Polarisation: foreground contrast and
  component separation

abstract:
  We evaluate the expected level of foreground contamination to the cosmic
microwave background (CMB) polarised radiation, focusing on the diffuse
emission from our own Galaxy. In particular, we perform a first attempt to
simulate an all sky template of polarised emission from thermal dust. This
study indicates that the foreground contamination to CMB $B$ modes is likely to
be relevant on all frequencies, and even at high Galactic latitudes. We review
the recent developments in the design of data analysis techniques dedicated to
the separation of CMB and foreground emissions in multi-frequency observations,
exploiting their statistical independence. We argue that the high quality and
detail of the present CMB observations represent an almost ideal statistical
dataset where these algorithms can operate with excellent performance. We
explicitly show that the recovery of CMB $B$ modes is possible even if they are
well below the foreground level, working at the arcmin. resolution at an almost
null computational cost. This capability well represents the great potentiality
of these new data analysis techniques, which should be seriously taken into
account for implementation in present and future CMB observations.


title:
Spectroscopic Confirmation of a Radio-Selected Galaxy Overdensity at
  z=1.11

abstract:
  We report the discovery of a galaxy overdensity at z=1.11 associated with the
z=1.110 high-redshift radio galaxy MG0442+0202. The group, CL0442+0202, was
found in a near-infrared survey of z>1 radio galaxies undertaken to identify
spatially-coincident regions with a high density of objects red in I-K' color,
typical of z>1 elliptical galaxies. Spectroscopic observations from the Keck
telescope reveal five galaxies within 35" of MG0442+0202 at 1.10<z<1.11. These
member galaxies have broad-band colors and optical spectra consistent with
passively-evolving elliptical galaxies formed at high redshift. A 45ks Chandra
X-Ray Observatory observation detects the radio galaxy and four point sources
within 15" of the radio galaxy, corresponding to a surface density two orders
of magnitude higher than average for X-ray sources at these flux levels,
S(0.5-2keV) > 5e-16 erg/cm2/s. One of these point sources is identified with a
radio-quiet, typeII quasar at z=1.863, akin to sources recently reported in
deep Chandra surveys. The limit on an extended hot intracluster medium in the
Chandra data is S(1-6keV) < 1.9e-15 erg/cm2/s (3-sigma, 30" radius aperture).
Though the X-ray observations do not confirm the existence of a massive, bound
cluster at z>1, the success of the optical/near-infrared targeting of
early-type systems near the radio galaxy validates searches using radio
galaxies as beacons for high-redshift large-scale structure. We interpret
CL0442+0202 to be a massive cluster in the process of formation.


title: Angular Spectra of Polarized Galactic Foregrounds

abstract:
  It is believed that magnetic field lines are twisted and bend by turbulent
motions in the Galaxy. Therefore, both Galactic synchrotron emission and
thermal emission from dust reflects statistics of Galactic turbulence. Our
simple model of Galactic turbulence, motivated by results of our simulations,
predicts that Galactic disk and halo exhibit different angular power spectra.
We show that observed angular spectra of synchrotron emission are compatible
with our model. We also show that our model is compatible with the angular
spectra of star-light polarization for the Galactic disk. Finally, we discuss
how one can estimate polarized microwave emission from dust in the Galactic
halo using star-light polarimetry.


title: Two Dimensional Adiabatic Flows onto a Black Hole: I. Fluid Accretion

abstract:
  When gas accretes onto a black hole, at a rate either much less than or much
greater than the Eddington rate, it is likely to do so in an "adiabatic" or
radiatively inefficient manner. Under fluid (as opposed to MHD) conditions, the
disk should become convective and evolve toward a state of marginal
instability. The resulting disk structure is "gyrentropic," with convection
proceeding along common surfaces of constant angular momentum, Bernoulli
function and entropy, called "gyrentropes." We present a family of
two-dimensional, self-similar models which describes the time-averaged disk
structure. We then suppose that there is a self-similar, Newtonian torque and
that the Prandtl number is large. This torque drives inflow and meridional
circulation and the resulting flow is computed. Convective transport will
become ineffectual near the disk surface. It is conjectured that this will lead
to a large increase of entropy across a "thermal front" which we identify as
the effective disk surface and the base of an outflow. The conservation of
mass, momentum and energy across this thermal front permits a matching of the
disk models to self-similar outflow solutions. We then demonstrate that
self-similar disk solutions can be matched smoothly onto relativistic flows at
small radius and thin disks at large radius. This model of adiabatic accretion
is contrasted with some alternative models that have been discussed recently.
The disk models developed in this paper should be useful for interpreting
numerical, fluid dynamical simulations. Related principles to those described
here may govern the behaviour of astrophysically relevant, magnetohydrodynamic
disk models.


title: On the First Anthropic Argument in Astrobiology

abstract:
  We consider the little-known anthropic argument of Fontenelle dealing with
the nature of cometary orbits, given a year before the publication of Newton's
Principia. This is particularly interesting in view of the rapid development of
the recently resurgent theories of cometary catastrophism and their role in the
modern astrobiological debates, for instance in the "rare Earth" hypothesis of
Ward and Brownlee.


title: The Temporal Aspect of the Drake Equation and SETI

abstract:
  We critically investigate some evolutionary aspects of the famous Drake
equation, which is usually presented as the central guide for the research on
extraterrestrial intelligence. It is shown that the Drake equation tacitly
relies on unverifiable and possibly false assumptions on both the
physico-chemical history of our Galaxy and the properties of advanced
intelligent communities. The importance of recent results of Lineweaver on
chemical build-up of inhabitable planets for SETI is emphasized. Two important
evolutionary effects are briefly discussed and the resolution of the
difficulties within the context of the phase-transition astrobiological models
sketched.


title:
Mass Composition of the Primary Cosmic Rays in the Energy Region
  10^{14}-10^{20} eV in Anomalous Diffusion Model

abstract:
  We discuss the problem of cosmic ray mass composition variation in wide
energy region 10^{14}-10^{20} eV. The mass composition predicted in the
framework of recently developed anomalous diffusion model is tested using the
results of CORSIKA calculations and experimental data on the depth of maximum
of extensive air showers. We show that the model predictions for the mass
composition are consistent with observations of different experiments.


title: The Crab pulsar and its red knot in the near-infrared

abstract:
  We present near-infrared observations obtained with ISAAC on the VLT of the
Crab pulsar and its environment. Photometry of the pulsar in Js, H and Ks shows
the pulsar spectrum to extend fairly smoothly from the UV/optical regime. PSF
subtraction of the pulsar allows us to study its immediate neighborhood in some
detail. In particular, the knot positioned just 0.6 arcsec from the pulsar has
been revealed in the IR. Using also archival HST data for the knot, we have
measured its broad band spectrum to rise steeply into the IR, in contrast to
the spectrum of the pulsar itself.


title:
Discovery of X-ray cyclotron absorption lines measures the magnetic
  field of an isolated neutron star

abstract:
  Isolated neutron stars are higly magnetized, fast rotating end points of
stellar evolution. They are now becoming directly observable through X-ray
astronomy, owing to their high surface temperatures. In particular, features in
their X-ray spectra could reveal the presence of atmospheres, or gauge their
unknown magnetic fields through the cyclotron process, as in the classic case
of X-ray binaries. All isolated neutron stars spectra observed so far, however,
appear as featureless thermal continua. The unique exception is 1E 1207.4-5209.
In its spectrum, previous observations had detected two deep absorption
features, still too undefined for any unambiguous interpretation. Here we
report on a much longer X-ray observation, in which the star's spectrum shows
three distinct features, regularly spaced at 0.7, 1.4 and 2.1 keV, plus a
fourth, lower significance one, at 2.8 keV. Such features vary in phase with
the star rotation. Cyclotron resonant absorption is their logical
interpretation, yielding a magnetic field strenght of 8x10^10 Gauss in the case
of electrons. This is the first direct measure of an isolated neutron star
magnetic field.


title: Surface photometry of LSB edge-on galaxies

abstract:
  We present results of surface photometry for eleven edge-on galaxies observed
with the 6-m telescope at the Special Astrophysical Observatory of the Russian
Academy of Sciences. The photometric scale length, the scale height, and the
central surface brightness of the stellar disks for the galaxies were found
using photometric cuts made parallel to the major and the minor axes for each
galaxy. We show that four galaxies in our sample that were visually classified
as objects of lowest surface brightness in the Revised Flat Galaxies Catalog
have LSB (low surface brightness) disks. Stellar disks of our LSB galaxies are
thinner than HSB (high surface brightness) ones. There is a good correlation
between the central surface brightness of the stellar disk and its ratio of
vertical to radial scales. The ratio of the disk photometric scales enables us
to estimate the mass of the spherical galactic subsystem using results from
numerical modeling. Combining our results with published rotation curves we
determined the mass of dark halos for the galaxies in our sample. The LSB
galaxies tend to harbor relatively more massive spherical subsystems than those
of HSB's. Indeed, we found no systematic difference between our LSB and HSB
objects in dark halo masses considering it separately from the bulge. At the
same time, the inferred mass/luminosity ratio for the LSB disks appears to be
systematically higher, when compared to the ratio for HSB ones.


title:
SINFONI - Integral Field Spectroscopy at 50 milli-arcsecond resolution
  with the ESO VLT

abstract:
  SINFONI is an adaptive optics assisted near-infrared integral field
spectrometer for the ESO VLT. The Adaptive Optics Module (built by the ESO
Adaptive Optics Group) is a 60-elements curvature-sensor based system, designed
for operations with natural or sodium laser guide stars. The near-infrared
integral field spectrometer SPIFFI (built by the Infrared Group of MPE)
provides simultaneous spectroscopy of 32 x 32 spatial pixels, and a spectral
resolving power of up to 3300. The adaptive optics module is in the phase of
integration; the spectrometer is presently tested in the laboratory. We provide
an overview of the project, with particular emphasis on the problems
encountered in designing and building an adaptive optics assisted spectrometer.


title:
ISM Properties in Low-Metallicity Environments II. The Dust Spectral
  Energy Distribution of NGC 1569

abstract:
  We present new 450 and 850 microns SCUBA data of the dwarf galaxy NGC 1569.
We construct the mid-infrared to millimeter SED of NGC 1569, using ISOCAM,
ISOPHOT, IRAS, KAO, SCUBA and MAMBO data, and model the SED in order to explore
the nature of the dust in low metallicity environments. The detailed modeling
is performed in a self-consistent way, synthesizing the global ISRF of the
galaxy using an evolutionary synthesis model with further constraints provided
by the observed MIR ionic lines and a photoionisation model. Our results show
that the dust properties are different in this low metallicity galaxy compared
to other more metal rich galaxies. The results indicate a paucity of PAHs
probably due to the destructive effects of the ISRF penetrating a clumpy
environment and a size-segregation of grains where the emission is dominated by
small grains of size ~3 nm, consistent with the idea of shocks having a
dramatic effect on the dust properties in NGC 1569. A significant millimetre
excess is present in the dust SED which can be explained by the presence of
ubiquitous very cold dust (T = 5-7 K). This dust component accounts for 40 to
70 % of the total dust mass in the galaxy (1.6 - 3.4 10^5 Msol) and could be
distributed in small clumps (size a few pc) throughout the galaxy. We find a
gas-to-dust mass ratio of 740 - 1600, larger than that of the Galaxy and a
dust-to-metals ratio of 1/4 to 1/7. We generate an extinction curve for NGC
1569, consistent with the modeled dust size distribution. This extinction curve
has relatively steep FUV rise and smaller 2175 Angstroms bump, resembling the
observed extinction curve of some regions in the Large Magellanic Cloud.


title: The galactic disk thickness and the mass of the spherical component

abstract:
  We present results of numerical modeling made for the galactic stellar disk
embedded in the spherical halo. The non-linear dynamics of bending
instabilities developed in the disk is studied. The axisymmetrical bending mode
is considered as a main factor increasing the disk thickness. The model
dependence between the disk thickness and the halo to disk mass ratio $M_h/M_d$
is inferred. The modeling results enable us to estimate the dark halo mass for
several edge-on galaxies. The obtained values of $M_h/M_d$ for the galaxies
considered are of order 1 - 2.


title: Control Software for the VERITAS Cherenkov Telescope System

abstract:
  The VERITAS collaboration is developing a system of initially 4 and
eventually 7 Cherenkov Telescopes of the 12 m diameter class for high
sensitivity gamma-ray astronomy in the >50 GeV energy range. In this
contribution we describe the software that controls and monitors the various
VERITAS sub-systems. The software uses an object-oriented approach to cope with
the complexities that arise from using sub-groups of the 7 VERITAS telescopes
to observe several sources at the same time. Inter-process communication is
based on the CORBA Object Request Broker protocol and watch-dog processes
monitor the sub-system performance.


title: Inflation from branes at angles

abstract:
  In this lecture I will review the present status of inflation within
string-based brane-world scenarios. The idea is to start from a supersymmetric
configuration with two parallel static Dp-branes, and slightly break the
supersymmetry conditions to produce a very flat potential for the field that
parametrises the distance between the branes, i.e. the inflaton field. This
breaking can be achieved in various ways. I will describe one of the simplest
examples described in Ref. [1]: two almost parallel D4-branes in a flat
compactified space, with a small relative angle between the branes, softly
breaking supersymmetry. If the breaking parameter is sufficiently small, a
large number of e-folds can be produced within the D-brane, for small changes
of the configuration in the compactified directions. Such a process is local,
i.e. it does not depend very strongly on the compactification space nor on the
initial conditions. Moreover, the breaking induces a very small velocity and
acceleration, which ensures very small slow-roll parameters and thus an almost
scale invariant spectrum of metric fluctuations, responsible for the observed
temperature and polarization anisotropies in the microwave background. Another
prediction of the model is the small amplitude of the gravitational wave
spectrum, which may not be detectable in the near future. Inflation ends as in
hybrid inflation, triggered by the negative curvature of the string tachyon
potential.


title:
High Resolution Spectroscopy of Balmer-Dominated Shocks in the RCW 86,
  Kepler and SN 1006 Supernova Remnants

abstract:
  We report results from high resolution optical spectroscopy of three
non-radiative galactic supernova remnants, RCW 86, Kepler's supernova remnant
and SN 1006. We have measured the narrow component H-alpha line widths in
Balmer-dominated filaments in RCW 86 and SN 1006, as well as the narrow
component width in a Balmer-dominated knot in Kepler's SNR. The narrow
component line widths measured in RCW 86 and Kepler's SNR show FWHM of 30-40
km/s, similar to what has been seen in other Balmer-dominated remnants. Of the
remnants in our sample, SN 1006 is the fastest shock (~3000 km/s). The narrow
component H-alpha and H-beta lines in this remnant have a FWHM of merely 21
km/s. Comparing the narrow component widths measured in our sample with those
measured in other remnants shows that the width of the narrow component does
not correlate in a simple way with the shock velocity. The implications for the
pre-heating mechanism responsible for the observed line widths are discussed.


title: The frequency of occurrence of novae hosting an ONe white dwarf

abstract:
  In this paper, we revisit the problem of the determination of the frequency
of occurrence of galactic nova outbursts which involve an oxygen-neon (ONe)
white dwarf. The improvement with respect to previous work on the subject
derives from the fact that we use the results that our evolutionary
calculations provide for the final mass and for the chemical profiles of
intermediate-to-massive primary components of close binary systems. In
particular, the final evolutionary stages, such as the carbon burning phase,
have been carefully followed for the whole range of masses of interest. The
chemical profiles obtained with our evolutionary code are of interest in
determining the chemical composition of the ejecta after being processed
through the thermonuclear runaway, although such other factors as the
efficiency of the mixing between the accreted material and that of the
underlying white dwarf must also be considered. In our calculations of the
frequency of occurrence of nova outbursts involving an ONe white dwarf, we also
take into account the observational selection effects introduced by the
different recurrence times of the outbursts and by the spatial distribution of
novae. In spite of the very different evolutionary sequences, we find that
approximately 1/3 of the novae observed in outburst should involve an
oxygen-neon white dwarf, in agreement with previous theoretical estimates.


title:
Minimum Velocity Dispersion in Stable Stellar Disks. Numerical
  Simulations

abstract:
  N-body dynamical simulations are used to analyze the conditions for the
gravitational stability of a three-dimensional stellar disk in the
gravitational field of two rigid spherical components--a bulge and a halo whose
central concentrations and relative masses vary over wide ranges. The number of
point masses N in the simulations varies from 40 to 500 thousands and the
evolution of the simulated models is followed over 10--20 rotation periods of
the outer edge of the disk. The initially unstable disks are heated and, as a
rule, reach a quasi-stationary equilibrium with a steady-state radial-velocity
dispersion $c_r$ over five to eight periods of rotation. The radial behavior of
the Toomre stability parameter $Q_T (r)$ for the final state of the disk is
estimated. Numerical models are used to analyze the dependence of the
gravitational stability of the disk on the relative masses of the spherical
components, disk thickness, degree of differential rotation, and initial state
of the disk. Formal application of existing, analytical, local criteria for
marginal stability of the disk can lead to errors in radial velocity dispersion
$c_r$ of more than a factor of 1.5. It is suggested that the approximate
constancy of $Q_T \simeq 1.2 -- 1.5$ for $r\simeq (1\div 2)\times L$ (where L
is the radial scale of disk surface density), valid for a wide range of models,
can be used to estimate upper limits for the mass and density of a disk based
on the observed distributions of the rotational velocity of the gaseous
component and of the stellar velocity dispersion.


title:
Circularly polarised radio emission from GRS 1915+105 and other X-ray
  binaries

abstract:
  I report the detection of circular polarisation, associated with relativistic
ejections, from the `microquasar' GRS 1915+105. I further compare detections
and limits of circular polarisation and circular-to-linear polarisation ratios
in other X-ray binaries. Since in at least two cases the dominance of linear
over circular polarisation or vice versa is a function of frequency, this seems
to indicate that this is a strong function of depolarisation in the source.
Furthermore, I note that circular polarisation has only been detected from
sources whose jets lie close to the plane of the sky, whereas we have quite
stringent limits on the circular polarisation of jets which lie close to the
line of sight.


title:
The line-of-sight distribution of the gas in the inner 60 pc of the
  Galaxy

abstract:
  2MASS K_S band data of the inner 60 pc of the Galaxy are used to reconstruct
the line-of-sight distances of the giant molecular clouds located in this
region. Using the 2MASS H band image of the same region, two different
populations of point sources are identified according to their flux ratio in
the two bands. The population of blue point sources forms a homogeneous
foreground that has to be subtracted before analyzing the K_S band image. The
reconstruction is made using two basic assumptions: (i) an axis-symmetric
stellar distribution in the region of interest and
  (ii) optically thick clouds with an area filling factor of ~1 that block all
light of stars located behind them. Due to the reconstruction method, the
relative distance between the different cloud complexes is a robust result,
whereas it is not excluded that the absolute distance with respect to Sgr A* of
structures located more than 10 pc in front of Sgr A* are understimated by up
to a factor of 2. It is shown that all structures observed in the 1.2 mm
continuum and in the CS(2-1) line are present in absorption. We place the 50 km
s^-1 cloud complex close to, but in front of, Sgr A*. The 20 km s^-1 cloud
complex is located in front of the 50 km s^-1 cloud complex and has a large LOS
distance gradient along the direction of the galactic longitude. The bulk of
the Circumnuclear Disk is not seen in absorption. This leads to an upper limit
of the cloud sizes within the Circumnuclear Disk of ~0.06 pc.


title:
The Ionized Gas and Nuclear Environment in NGC 3783 III. Detection of a
  Decreasing Radial Velocity in an Intrinsic UV Absorber

abstract:
  We report an intrinsic absorber with decreasing outflow velocity in the
Seyfert 1 galaxy NGC 3783. This is the first detection of a change in radial
velocity in an outflow associated with a Seyfert galaxy. These results are
based on measurements from 18 observations with the Space Telescope Imaging
Spectrograph aboard the Hubble Space Telescope, obtained between 2000 February
and 2002 January. In two intervals separated by ~13 and 9 months, the
absorption lines in the kinematic component with highest outflow velocity
exhibited mean redward velocity shifts of ~35 and 55 km/s, respectively. The
rate of velocity decrease was 2.2 +/- 0.6 times more rapid in the second
interval. No variations in absorption velocities were detected in the other
kinematic components. We explore potential interpretations of the observed
velocity shifts: radial deceleration of the UV absorber due to a change in
either the speed or direction of motion of the outflow, and the evolution of a
continuous flow across our line of sight to the emission source.


title: Smooth maps from clumpy data: generalizations

abstract:
  In a series of papers (Lombardi & Schneider 2001, 2002) we studied in detail
the statistical properties of an interpolation technique widely used in
astronomy. In particular, we considered the average interpolated map and its
covariance under the hypotheses that the map is obtained by smoothing unbiased
measurements of an unknown field, and that the measurements are uniformly
distributed on the sky. In this paper we generalize the results obtained to the
case of observations carried out only on a finite field and distributed on the
field with a non-uniform density. These generalizations, which are required in
many astronomically relevant cases, still allow an exact, analytical solution
of the problem. We also consider a number of properties of the interpolated
map, and provide asymptotic expressions for the average map and the two-point
correlation function which are valid at high densities.


title:
Structure of Dark Matter Halos From Hierarchical Clustering. III.
  Shallowing of The Inner Cusp

abstract:
  We investigate the structure of the dark matter halo formed in the cold dark
matter scenarios by N-body simulations with parallel treecode on GRAPE cluster
systems. We simulated 8 halos with the mass of $4.4\times 10^{14}M_{\odot}$ to
$1.6\times 10^{15}M_{\odot}$ in the SCDM and LCDM model using up to 30 million
particles. With the resolution of our simulations, the density profile is
reliable down to 0.2 percent of the virial radius. Our results show that the
slope of inner cusp within 1 percent virial radius is shallower than -1.5, and
the radius where the shallowing starts exhibits run-to-run variation, which
means the innermost profile is not universal.


title: Three-Body Encounters of Black Holes in Globular Clusters

abstract:
  Evidence has been mounting for the existence of black holes with masses from
10^2 to 10^4 M_Solar associated with stellar clusters. Such intermediate-mass
black holes (IMBHs) will encounter other black holes in the dense cores of
these clusters. The binaries produced in these interactions will be perturbed
by other objects as well thus changing the orbital characteristics of the
binaries. These binaries and their subsequent mergers due to gravitational
radiation are important sources of gravitational waves. We present the results
of numerical simulations of high mass ratio encounters, which help clarify the
interactions of intermediate-mass black holes in globular clusters and help
determine what types of detectable gravitational wave signatures are likely.


title: Substructures in Cold Dark Matter Haloes

abstract:
  We analyse the properties of substructures within dark matter halos
(subhalos) using a set of high-resolution numerical simulations of the
formation of structure in a Lambda-CDM Universe. Our simulation set includes 11
high-resolution simulations of massive clusters as well as a region of mean
density, allowing us to study the spatial and mass distribution of
substructures down to a mass resolution limit of 10^9 h^(-1)Mo. We also
investigate how the properties of substructures vary as a function of the mass
of the `parent' halo in which they are located. We find that the substructure
mass function depends at most weakly on the mass of the parent halo and is well
described by a power-law. The radial number density profiles of substructures
are steeper in low mass halos than in high mass halos. More massive
substructures tend to avoid the centres of halos and are preferentially located
in the external regions of their parent halos. We also study the mass accretion
and merging histories of substructures, which we find to be largely independent
of environment. We find that a significant fraction of the substructures
residing in clusters at the present day were accreted at redshifts z < 1. This
implies that a significant fraction of present-day `passive' cluster galaxies
should have been still outside the cluster progenitor and more active at z~1.


title: Evidence for a Significant Blazar Contamination in CMB Anisotropy Maps

abstract:
  The analysis of the recent WMAP source catalog shows that the vast majority
of bright foreground extragalactic sources detected in CMB maps are Blazars. In
this paper we calculate the contamination of CMB anisotropy maps by this type
of flat-spectrum, strongly variable and polarized extragalactic radio sources
using up-to-date results from recent deep multi-frequency surveys. We found
that more than 50 known Blazars (or Blazar candidates) are included in the
90/150 GHz BOOMERANG anisotropy maps, a factor > 15 larger than previously
reported. Using a recent derivation of the Blazar radio LogN-LogS we calculate
that these sources induce an average sky brightness of 0.2 Jy/deg^2,
corresponding to an average temperature of ~3-5 muK. Moreover, we find that the
associated level of fluctuations is of the order of C_{l, Blazar}= 1.3 10^{-2}
mu K^2 sr at 41 GHz. Taking into account both Blazar variability and the many
steep-spectrum radio sources that flatten at high frequencies, as well as the
contribution of radio-galaxies, we find that the level of residual fluctuation
due to discrete extragalactic foreground sources could be factor of ~2 - 3
higher than the above estimate. We show that the Blazar induced fluctuations
contaminate the CMB spectrum at the level of ~ 20-50 % at l = 500 and 50-100 %
at l = 800. Careful cleaning for Blazar contamination of high sensitivity/high
resolution CMB maps is therefore necessary before firm conclusions about weak
features, like secondary high-l peaks of the CMB power spectrum or very weak
signals like CMB polarization measurements, can be achieved.


title: Antiprotons in cosmic rays from neutralino annihilation

abstract:
  We calculate the antiproton flux due to relic neutralino annihilations, in a
two-dimensional diffusion model compatible with stable and radioactive cosmic
ray nuclei. We find that the uncertainty in the primary flux induced by the
propagation parameters alone is about two orders of magnitude at low energies,
and it is mainly determined by the lack of knowledge on the thickness of the
diffusive halo. On the contrary, different dark matter density profiles do not
significantly alter the flux: a NFW distribution produces fluxes which are at
most 20% higher than an isothermal sphere. The most conservative choice for
propagation parameters and dark matter distribution normalization, together
with current data on cosmic antiprotons, cannot lead to any definitive
constraint on the supersymmetric parameter space, neither in a low-energy
effective MSSM, or in a minimal SUGRA scheme. However, if the best choice for
propagation parameters - corresponding to a diffusive halo of L=4 kpc - is
adopted, some supersymmetric configurations with the neutralino mass of about
100 GeV should be considered as excluded. An enhancement flux factor - due for
instance to a clumpy dark halo or to a higher local dark matter density - would
imply a more severe cut on the supersymmetric parameters.


title: Enhanced Angular Momentum Transport in Accretion Disks

abstract:
  The status of our current understanding of angular momentum transport in
accretion disks is reviewed. The last decade has seen a dramatic increase both
in the recognition of key physical processes and in our ability to carry
through direct numerical simulations of turbulent flow. Magnetic fields have at
once powerful and subtle influences on the behavior of (sufficiently) ionized
gas, rendering them directly unstable to free energy gradients. Outwardly
decreasing angular velocity profiles are unstable. The breakdown of Keplerian
rotation into MHD turbulence may be studied in some numerical detail, and key
transport coefficients may be evaluated. Chandra observations of the Galactic
Center support the existence of low luminosity accretion, which may ultimately
prove amenable to global three-dimensional numerical simulation.


title: Recent Results from the AMANDA Experiment

abstract:
  AMANDA (Antarctic Muon And Neutrino Detector Array) is a neutrino telescope
built under the southern polar icecap and its scope is to explore the
possibility to detect high energy cosmic neutrinos. This should generate
insight into the powerful celestial objects where acceleration mechanisms can
bring up to $10^{20}$ eV. We describe the achievements and results from the
AMANDA-B10 prototype and the preliminary results from the current AMANDA-II
detector which show dramatic increase in sensitivity.


title: Decelerating Flows in TeV Blazars

abstract:
  The peak of the de-absorbed energy distribution of the TeV emitting BLs can
reach values up to ~10 TeV. In the context of SSC models of relativistic
uniformly moving blobs of plasma, such high energy peak emission can be
reproduced only by assuming Doppler factors delta ~ 50. However, such high
values strongly disagree with the unification of FR I radio galaxies and BLs.
Additionally, the recent detections of slow, possibly sub-luminal velocities in
the sub-pc scale jets of the TeV BLS MKN 421 and MKN 501 suggest that the jets
in these sources decelerate very early to mildly relativistic velocities (Gamma
\~ a few). Here, we examine the possibility that the relativistic flow in the
TeV BLs decelerates lognitudinally. In this case, modest Lorentz factors
(Gamma~15), decelerating down to values compatible with the recent
interferometric observations, can reproduce the ~ few TeV peak energy of these
sources. Furthermore, such decelerating flows naturally reproduce the observed
broadband BL-FR I luminosity ratios.


title: Are Cluster Magnetic Fields Primordial ?

abstract:
  We present results of a detailed and fully non-linear numerical and
analytical investigation of magnetic field evolution from the very earliest
cosmic epochs to the present. We find that, under reasonable assumptions
concerning the efficiency of a putative magnetogenesis era during cosmic phase
transitions, surprisingly strong magnetic fields 10^{-13} - 10^{-11} Gauss, on
comparatively small scales 100 pc - 10 kpc may survive to the present. Building
on prior work on the evolution of magnetic fields during the course of
gravitational collapse of a cluster, which indicates that pre-collapse fields
of 4\times 10^{-12} Gauss extant on small scales may suffice to produce
clusters with acceptable Faraday rotation measures, we question the widely hold
view that cluster magnetic fields may not be entirely of primordial origin.


title:
Optical and Infrared Properties of the 2 Ms Chandra Deep Field-North
  X-ray Sources

abstract:
  We present an optical and NIR catalog for the X-ray sources in the 2 Ms
Chandra observation of the Hubble Deep Field-North region. We have high-quality
multicolor images of all 503 X-ray point sources and reliable spectroscopic
redshifts for 284. We spectroscopically identify six z>1 type II quasars. Our
spectroscopic completeness for the R<24 sources is 87%. The spectroscopic
redshift distribution shows two broad redshift spikes that have clearly grown
over those originally seen in the 1 Ms exposure. The spectroscopically
identified extragalactic sources already comprise 75% of the measured 2-8 keV
light. Redshift slices versus 2-8 keV flux show that an impressive 54% of the
measured 2-8 keV light arises from sources at z<1 and 68% from sources at z<2.
We use seven broadband colors and a Bayesian photometric redshift estimation
code to obtain photometric redshifts. The photometric redshifts are within 25%
of the spectroscopic redshifts for 94% of the non-broad-line sources with both
photometric and spectroscopic measurements. We use our wide wavelength coverage
to determine rest-frame colors for the X-ray sources with spectroscopic or
photometric redshifts. Many of the X-ray sources have the rest-frame colors of
evolved red galaxies and there is very little evolution in these colors with
redshift. We also determine absolute magnitudes and find that many of the
non-broad-line sources are more luminous than Mstar, even at high redshifts. We
therefore infer that deep X-ray observations may provide an effective way of
locating Mstar galaxies with colors similar to present-day early-type galaxies
to high redshifts. (Abridged)


title: Black Hole Binaries

abstract:
  We review the properties of 40 X-ray binaries that contain either a confirmed
black hole or a black hole candidate. After discussing briefly the significance
of these Galactic black holes to both astronomy and physics, we present basic
data for all 40 systems, review the physics of mass accretion onto black holes,
and then show seven-year light curves of 20 systems. The second half of this
work is a far-reaching review of the canonical emission states of black hole
binaries, which is based on X-ray, radio and gamma-ray data. For several
selected black holes, we show 33 pairs of X-ray energy and power density
spectra and use these spectra as a basis for introducing modified definitions
of the canonical X-ray emission states of an accreting black hole. We highlight
the physical structures and some of the emission mechanisms associated with
each emission state. In the final pages we examine both low- and high-frequency
quasi-periodic oscillations. A recurring theme of the review is the importance
of these black holes as potential sites for tests of general relativity.
Accordingly, we stress phenomena that originate in strong gravity, such as
relativistic Fe emission lines and thermal continuum emission, both of which
arise in the inner accretion disk. Especially important in this regard are the
high-frequency (40-450 Hz) quasi-periodic oscillations observed for seven black
holes, three of which show evidence for commensurate (3:2) pairs of
frequencies.


title: Stellar dynamics in the central arcsecond of our galaxy

abstract:
  We present proper motions for $>$40 stars at projected distances $\leq1.2''$
from Sagittarius A* (Sgr A*). We find evidence on a $\geq2\sigma$ level for
radial anisotropy of the cluster of stars within $1''$ of Sgr A*. We find no
evidence for a stationary source or variable source at the position of Sgr A*.
We confirm/find accelerated motion for 6 stars, with 4 stars having passed the
pericenter of their orbits during the observed time span. We
calculated/constrained the orbital parameters of these stars. All orbits have
moderate to high eccentricities. We discuss the possible bias in detecting
preferentially orbits with high eccentricities. We find that the center of
acceleration for all the orbits coincides with the radio position of Sgr A*.
  From the orbit of the star S2, the currently most tightly constrained one, we
determine the mass of Sgr A* to be $3.3\pm0.7\times10^{6}$M$_{\odot}$ and its
position to $2.0\pm2.4$ mas East and $2.7\pm4.5$ mas South of the nominal radio
position. The mass estimate for the central dark mass from the orbit of S2 is
fully consistent with the mass estimate of $3.4\pm0.5\times10^{6}$M$_{\odot}$
obtained from stellar proper motions within $1.2''$ of Sgr A* using a
Leonard-Merritt mass estimator. We find that radio astronomical observations of
the proper motion of Sgr A* in combination with its intrinsic source size place
at the moment the tightest constraints on the mass density of Sgr A*, which
must exceed $\rho_{\mathrm{Sgr
A*}}>3\times10^{19}\mathrm{M}_{\odot}\mathrm{pc}^{-3}$.


title: Star Formation at z~6: i-dropouts in the ACS GTO fields

abstract:
  Using an i-z dropout criterion, we determine the space density of z~6
galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of
23 objects are found over 46 arcmin^2, or ~0.5 objects/arcmin^2 down to z~27.3
(6 sigma; all AB mag) (including one probable z~6 AGN). Combining deep ISAAC
data for our RDCS1252-2927 field (J~25.7 and Ks~25.0 (5 sigma)) and NICMOS data
for the HDF North (JH~27.3 (5 sigma)), we verify that these dropouts have flat
spectral slopes. i-dropouts in our sample range in luminosity from ~1.5 L*
(z~25.6) to ~0.3 L* (z~27.3) with the exception of one very bright candidate at
z~24.2. The half-light radii vary from 0.09" to 0.29", or 0.5 kpc to 1.7 kpc.
We derive the z~6 rest-frame UV luminosity density using three different
procedures, each utilizing simulations based on a CDF South V dropout sample.
First, we compare our findings with a no-evolution projection of this V-dropout
sample. We find 23+/-25% more i-dropouts than we predict. Adopting previous
results to z~5, this works out to a 20+/-29% drop in the luminosity density
from z~3 to z~6. Second, we use these same V-dropout simulations to derive a
selection function for our i-dropout sample and compute the UV-luminosity
density (7.2+/-2.5 x 10^25 ergs/s/Hz/Mpc^3 down to z~27). We find a 39+/-21%
drop over the same redshift range. This is our preferred value and suggests a
star formation rate of 0.0090+/-0.0031 M_sol/yr/Mpc^3 to z~27, or ~0.036+/-
0.012 M_sol/yr/Mpc^3 extrapolating the LF to the faint limit. Third, we follow
a very similar procedure, but assume no incompleteness, finding a luminosity
density which is ~2-3X lower. This final estimate constitutes a lower limit.
All three estimates are within the canonical range of luminosity densities
necessary for reionization of the universe at this epoch. (abridged)


title: The Hubble Constant from the Gravitational Lens B1608+656

abstract:
  We present a refined gravitational lens model of the four-image lens system
B1608+656 based on new and improved observational constraints: (i) the three
independent time-delays and flux-ratios from VLA observations, (ii) the
radio-image positions from VLBA observations, (iii) the shape of the
deconvolved Einstein Ring from optical and infrared HST images, (iv) the
extinction-corrected lens-galaxy centroids and structural parameters, and (v) a
stellar velocity dispersion, sigma_ap=247+-35 km/s, of the primary lens galaxy
(G1), obtained from an echelle spectrum taken with the Keck--II telescope. The
lens mass model consists of two elliptical mass distributions with power-law
density profiles and an external shear, totaling 22 free parameters, including
the density slopes which are the key parameters to determine the value of H_0
from lens time delays. This has required the development of a new lens code
that is highly optimized for speed. The minimum-chi^2 model reproduces all
observations very well, including the stellar velocity dispersion and the shape
of the Einstein Ring. A combined gravitational-lens and stellar dynamical
analysis leads to a value of the Hubble Constant of H_0=75(+7/-6) km/s/Mpc (68
percent CL; Omega_m=0.3, Omega_Lambda=0.7. The non-linear error analysis
includes correlations between all free parameters, in particular the density
slopes of G1 and G2, yielding an accurate determination of the random error on
H_0. The lens galaxy G1 is ~5 times more massive than the secondary lens galaxy
(G2), and has a mass density slope of gamma_G1=2.03(+0.14/-0.14) +- 0.03 (68
percent CL) for rho~r^-gamma', very close to isothermal (gamma'=2). (Abridged)


title:
Reconstructing Three-dimensional Structure of Underlying Triaxial Dark
  Halos From Xray and Sunyaev-Zel'dovich Effect Observations of Galaxy Clusters

abstract:
  While the use of galaxy clusters as {\it tools} to probe cosmology is
established, their conventional description still relies on the spherical
and/or isothermal models that were proposed more than 20 years ago. We present,
instead, a deprojection method to extract their intrinsic properties from X-ray
and Sunyaev--Zel'dovich effect observations in order to improve our
understanding of cluster physics. First we develop a theoretical model for the
intra-cluster gas in hydrostatic equilibrium in a triaxial dark matter halo
with a constant axis ratio. In this theoretical model, the gas density profiles
are expressed in terms of the intrinsic properties of the dark matter halos.
Then, we incorporate the projection effect into the gas profiles, and show that
the gas surface brightness profiles are expressed in terms of the
eccentricities and the orientation angles of the dark halos. For the practical
purpose of our theoretical model, we provide several empirical fitting formulae
for the gas density and temperature profiles, and also for the surface
brightness profiles relevant to X-ray and Sunyaev--Zel'dovich effect
observations. Finally, we construct a numerical algorithm to determine the halo
eccentricities and orientation angles using our model, and demonstrate that it
is possible in principle to reconstruct the 3D structures of the dark halos
from the X-ray and/or Sunyaev-Zel'dovich effect cluster data alone without
requiring priors such as weak lensing informations and without relying on such
restrictive assumptions as the halo axial symmetry about the line-of-sight.


title: The HI environment of the Sculptor dwarf spheroidal galaxy

abstract:
  New observations of the neutral hydrogen (HI) in and around the line of sight
of the Sculptor dwarf spheroidal (dSph) are presented. The data obtained with
the single-dish Parkes telescope cover a large area of 7\degr x 7\degr in the
direction of the dwarf, and have resolutions of 15\farcm x 1.12 km/s. The
Australia Telescope Compact Array (ATCA) was used to map a smaller area of
2\degr x 2\degr centered on the direction of the dwarf with higher resolutions
(350\arcsec x 140\arcsec x 1.65 km/s). Many HI structures having velocities
outside the range of the normal Galactic disk velocities were detected,
including the two Sculptor clouds (northeast and southwest) of Carignan et al.
(1998, C98). The present study shows the total extent of the C98 clouds. We
derived heliocentric radial velocities for the NE and SW clouds of 100.2\pm 0.9
km/s and 105.1\pm 0.3 km/s, respectively. The intensity-weighted mean HI
velocity for both clouds is 104.1\pm 0.4 km/s. The mass of each cloud is
(4.1\pm 0.2) x 10^4 M_\odot (NE cloud) and (1.93\pm 0.02) x 10^5 M_\odot (SW
cloud) at the Sculptor dSph distance (79 kpc).


title:
Spatially resolved spectroscopy of Coma cluster early -- type galaxies:
  III. The stellar population gradients

abstract:
  We derive central values and logarithmic gradients for the Hbeta, Mg and Fe
indices of 35 early-type galaxies in the Coma cluster. We find that pure
elliptical galaxies have on average slightly higher velocity dispersions, lower
Hbeta, and higher metallic line-strengths than galaxies with disks (S0). The
gradients strongly correlate with the gradients of sigma, but only weakly with
the central index values and galaxy velocity dispersion. Using stellar
population models with variable element abundance ratios from Thomas, Maraston
& Bender (2003a) we derive average ages, metallicities and [alpha/Fe] ratios in
the center and at the effective radius. We find that the [alpha/Fe] ratio
correlates with velocity dispersion and drives 30% of the Mg-sigma relation,
the remaining 70% being caused by metallicity variations. We derive negative
metallicity gradients (-0.16 dex per decade) that are significantly flatter
than what is expected from gaseous monolithic collapse models, pointing to the
importance of mergers in the galaxy formation history. The gradients in age are
negligible, implying that no significant residual star formation has occurred
either in the center or in the outer parts of the galaxies, and that the
stellar populations at different radii must have formed at a common epoch. For
the first time we derive the gradients of the [alpha/Fe] ratio and find them
very small on the mean. Hence, [alpha/Fe] enhancement is not restricted to
galaxy centers but it is a global phenomenon. Our results imply that the
Mg-sigma local relation inside a galaxy, unlike the global Mg-sigma relation,
must be primarily driven by metallicity variations alone.


title: A Geometric Determination of the Distance to the Galactic Center

abstract:
  We report new astrometric and spectroscopic observations of the star S2
orbiting the massive black hole in the Galactic Center, which were taken at the
ESO VLT with the adaptive optics assisted, near-IR camera NAOS/CONICA and the
near-IR integral field spectrometer SPIFFI. We use these data to determine all
orbital parameters of the star with high precision, including the Sun-Galactic
Center distance, which is a key parameter for calibrating stellar standard
candles and an important rung in the extragalactic distance ladder. Our deduced
value of Ro = 8.0 +/- 0.4 kpc is the most accurate primary distance measurement
to the center of the Milky Way and has minimal systematic uncertainties of
astrophysical origin. It is in excellent agreement with other recent
determinations of Ro.


title:
Atmospheric and Galactic Production and Propagation of Light Antimatter
  Nuclei

abstract:
  The production and propagation of light antimatter nuclei has been calculated
using inclusive antiproton production cross sections from a new data analysis,
and coalescence models for the production of composite particles. Particles
were propagated using recently proven phenomenological approaches. The
atmospheric secondary flux is evaluated for the first time. The Galactic flux
obtained are larger than those obtained previously in similar calculations. The
non-annihilating scattering contributions of the propagated particles are
introduced. The preliminary results are shown and discussed.


title:
First Detection of Polarization of the Submillimetre Diffuse Galactic
  Dust Emission by Archeops

abstract:
  We present the first determination of the Galactic polarized emission at 353
GHz by Archeops. The data were taken during the Arctic night of February 7,
2002 after the balloon--borne instrument was launched by CNES from the Swedish
Esrange base near Kiruna. In addition to the 143 GHz and 217 GHz frequency
bands dedicated to CMB studies, Archeops had one 545 GHz and six 353 GHz
bolometers mounted in three polarization sensitive pairs that were used for
Galactic foreground studies. We present maps of the I, Q, U Stokes parameters
over 17% of the sky and with a 13 arcmin resolution at 353 GHz (850 microns).
They show a significant Galactic large scale polarized emission coherent on the
longitude ranges [100, 120] and [180, 200] deg. with a degree of polarization
at the level of 4-5%, in agreement with expectations from starlight
polarization measurements. Some regions in the Galactic plane (Gem OB1,
Cassiopeia) show an even stronger degree of polarization in the range 10-20%.
Those findings provide strong evidence for a powerful grain alignment mechanism
throughout the interstellar medium and a coherent magnetic field coplanar to
the Galactic plane. This magnetic field pervades even some dense clouds.
Extrapolated to high Galactic latitude, these results indicate that
interstellar dust polarized emission is the major foreground for PLANCK-HFI CMB
polarization measurement.


title:
The metal absorption systems of the QSO 0103-260 and the galaxy redshift
  distribution in the FORS Deep Field

abstract:
  Using the Uves echelle spectrograph at the ESO VLT, we observed the
absorption line spectrum of the QSO 0103-260 in the Fors Deep Field. In
addition to the expected Ly-alpha forest lines, we detected at least 16 metal
absorption systems with highly different ionization levels in the observed
spectral range. The redshifts of the metal absorption systems are strongly
correlated with the redshift distribution of the high-z galaxies in the Fors
Deep Field and with the strength (but not the number density) of the Ly-alpha
forest lines. Both the metal systems and the galaxies show clustering at least
up to the QSO emission line redshift of 3.365, but only few of these galaxy
accumulations seem to form bound systems.


title:
The AMS-02 RICH Imager Prototype - In-Beam Tests with 20 GeV/c per
  Nucleon Ions -

abstract:
  A prototype of the AMS Cherenkov imager (RICH) has been tested at CERN by
means of a low intensity 20 GeV/c per nucleon ion beam obtained by
fragmentation of a primary beam of Pb ions. Data have been collected with a
single beam setting, over the range of nuclear charges 2<Z<~45 in various beam
conditions and using different radiators. The charge Z and velocity beta
resolutions have been measured.