title: The Spectroscopic Properties of Bright Extragalactic Planetary Nebulae

abstract:
  The properties of bright extragalactic planetary nebulae are reviewed based
upon the results of low and high resolution spectroscopy. It is argued that
bright extragalactic planetary nebulae from galaxies (or subsystems) with and
without star formation have different distributions of central star temperature
and ionization structure. As regards the chemical compositions, oxygen and neon
are generally found to be unchanged as a result of the evolution of the stellar
progenitors. Nitrogen enrichment may occur as a result of the evolution of the
progenitors of bright planetary nebulae in all stellar populations, though this
enrichment may be (more) random in old stellar populations. Helium abundances
appear to be influenced by the chemical evolution of the host galaxy, with
planetary nebulae in dwarf spheroidals having systematically elevated
abundances. Neither the age nor the metallicity of the progenitor stellar
population has a strong effect upon the kinematics observed for nebular shells.
Both the range of expansion velocites, 8-28 km/s, and the typical expansion
velocity, ~18 km/s, are found to be relatively constant in all galaxies. On the
other hand, bright planetary nebulae in the bulge of M31 have systematically
higher expansion velocities than their counterparts in M31's disk. The
expansion velocities show no trend with nebular Hbeta luminosity, apart from a
lack of large expansion velocities at the highest luminosities (the youngest
objects), but appear to correlate with the 5007/Hbeta ratio, at least until
this ratio saturates. These results suggest a link between the evolution of the
nebular shells and central stars of bright extragalactic planetary nebulae.


title:
Inner-shell ionization, radiative losses and thermal conductivity in
  young SNRs

abstract:
  Self-consistent treatment of time-dependent ionization in hydrodynamical
calculations of the X-ray emission from young supernova remnants has been
performed. The novel feature of the calculations is that K_alpha lines from
species produced by inner-shell collisional ionization are included. Parameters
of the shocked ejecta are found from fitting the model spectrum to the observed
one. The application of the method to Tycho SNR using the classical
deflagration model W7 for the explosion enables us to well reproduce the
observed X-ray spectra and radial brightness profiles of the remnant.


title: From Tidal Dwarf Galaxies to Satellite Galaxies

abstract:
  Cosmological models have granted dwarf galaxies a key role: their properties
constrain the distribution of dark matter and the physical evolution of their
hosts. There is increasing evidence that objects with masses of dwarf galaxies
form in the tidal tails of colliding galaxies and speculations that they could
become satellite-like galaxies around their progenitors and thus be
cosmologically important. Yet, whether these "Tidal Dwarf Galaxies" (TDGs)
candidates are really long-lived and not only present in young interacting
systems is still an open question to which numerical simulations may give
answers. We present a set of 96 simulations of colliding galaxies with various
mass ratios and encounter geometries, and statistically study the evolution of
their TDG candidates. Among the 593 substructures initially identified in tidal
tails, about 75% fall back onto their progenitor or are disrupted in a few 10^8
years. The remaining 25% become long-lived bound objects that typically survive
more than 2Gyr with masses above 10^8 M_sun. These long-lived, satellite-like
objects, are found to form in the outer most regions of the tidal tails. We
infer several basic properties that dwarf galaxies should meet to have a tidal
origin and apply these criteria to the Local Group dwarfs. We also find that
the presence of TDGs would foster the anisotropy observed in the distribution
of satellite galaxies around their host. Identifying the conditions required
for interacting systems to form long-lived tidal dwarfs, we roughly estimate
their contribution to the overall population of dwarfs. We conclude that a
small but significant fraction of them - typically a few percent, and possibly
more in dense environments or around early-type galaxies - could be of tidal
origin.


title: A quasi periodic signal with ultra low frequency discovered in V0332+53?

abstract:
  The reported likely QPO is found to be an instrumental effect, which was
never clarified in any INTEGRAL related literatures. The paper should therfore
be withdrawn.


title:
Long-Term V-Band Monitoring of the Bright Stars of M33 at the Wise
  Observatory

abstract:
  We have conducted a long-term V-band photometric monitoring of M33 on 95
nights during four observing seasons (2000 - 2003). A total number of 6418
lightcurves of bright objects in the range of 14 - 21 mag have been obtained.
All measurements are publicly available. A total of 127 new variables were
detected, of which 28 are periodic. Ten previously known non-periodic variables
were identified as periodic, 3 of which are Cepheids, and another previously
known periodic variable was identified as an eclipsing binary. Our derived
periods range from 2.11 to almost 300 days. For 50 variables we have combined
our observations with those of the DIRECT project, obtaining lightcurves of up
to 500 measurements, with a time-span of ~7 years. We have detected a few
interesting variables, including a 99.3 day periodic variable with a 0.04 mag
amplitude, at the position of SNR 19.


title: Mass downsizing and "top-down" assembly of early-type galaxies

abstract:
  We present a new analysis of the rest-frame B-band COMBO-17 and DEEP2
luminosity functions (LFs) of early-type galaxies (ETGs) as a function of
luminosity and mass. Our aim is to place new stringent constraints on the
evolution of ETGs since z~1. We correct the LF($z$) data for the luminosity
dimming assuming pure luminosity evolution. However, instead of relying on
stellar population synthesis model--dependent assumptions, we adopt the
empirical luminosity dimming rate derived from the evolution of the Fundamental
Plane of field and cluster massive ETGs.Our results show that the amount of
evolution for the ETG population depends critically on the range of luminosity
and masses considered. While the number density of luminous (massive) ETGs with
M_B(z=0)< -20.5 (Mass > 10^11 M_Sun) is nearly constant since z~0.8, less
luminous galaxies display a deficit which grows with redshift and that can be
explained with a gradual population of the ETG "red sequence" by the
progressive quenching of star formation in galaxies less massive than ~10^11
M_Sun. At each redshift there is a critical mass above which virtually all ETGs
appear to be in place, and this fits well in the now popular "downsizing"
scenario. However, ``downsizing'' does not appear to be limited to star
formation, but the concept may have to be extended to the mass assembly itself
as the build-up of the most massive galaxies preceeds that of the less massive
ones. This evolutionary trend is not reproduced by the most recent theoretical
simulations even when they successfully reproduce "downsizing" in star
formation.


title: Cosmological Neutrino Entanglement and Quantum Pressure

abstract:
  Context: The widespread view that cosmological neutrinos, even if massive,
are well described since the decoupling redshift z~10^10 down to the present
epoch by an almost perfectly collisionless fluid of classical point particles
is re-examined. Aims: In view of the likely sub-eV rest mass of neutrinos, the
main effects due to their fermionic nature are studied. Methods: By numerical
means we calculate the accurate entropy, fugacity and pressure of cosmological
neutrinos in the Universe expansion. By solving the Schroedinger equation we
derive how and how fast semi-degenerate identical free fermions become
entangled. Results: We find that for sub-eV neutrinos the exchange degeneracy
has significantly increased during the relativistic to non-relativistic
transition epoch at z~10^4-10^5. At all times neutrinos become entangled in
less than 10^-6 s, much faster than any plausible decoherence time. The total
pressure is increased by quantum effect from 5% at high redshifts to 68% at low
redshifts with respect to a collisionless classical fluid. Conclusions: The
quantum overpressure has no dynamical consequences in the homogeneous regime at
high redshifts, but must be significant for neutrino clustering during the
non-linear structure formation epoch at low redshifts.


title:
SPITZER Observations of z~3 Lyman Break Galaxies: stellar masses and
  mid-infrared properties

abstract:
  We describe the spectral energy distributions (SEDs) of Lyman Break Galaxies
(LBGs) at z~3 using deep mid-infrared and optical observations of the Extended
Groth Strip, obtained with IRAC and MIPS on board Spitzer and from the ground,
respectively. We focus on LBGs with detections at all four IRAC bands, in
particular the 26 galaxies with IRAC 8 micron band (rest--frame K-band)
detections. We use stellar population synthesis models and probe the stellar
content of these galaxies. Based on best--fit continuous star-formation models
we derive estimates of the stellar mass for these LBGs. As in previous studies,
we find that a fraction of LBGs have very red colors and large estimated
stellar masses (M_stellar > 5 x 10 ^{10} M_solar): the present Spitzer data
allow us, for the first time, to study these massive LBGs in detail. We discuss
the link between these LBGs and submm-luminous galaxies.We find that the number
density of these massive LBGs at high redshift is higher than predicted by
current semi-analytic models of galaxy evolution.


title: Statistical Analysis of Quasar Data and Hubble Law

abstract:
  The linearity of the Hubble relationship (i.e. between m and z) has been
tested for galaxies and supernovea for low redshifts. We have studied this
relationship for quasars for data taken from Veron Cetti Catalogue(2003).The
data from Veron Cetti Catalogue for quasars appear to be truncated. The data
have been analyzed using various statistical methods which are suitable for
analysing the truncated data. This analysis shows lineraity (in log z) of
Hubble law for very small z but non-linearity for high redshift.This will shed
new light not only on the quasar astronomy but also in the cosmological debate.


title: Radial Velocity Studies of Close Binary Stars. XI

abstract:
  Radial-velocity measurements and sine-curve fits to the orbital radial
velocity variations are presented for ten close binary systems: DU Boo, ET Boo,
TX Cnc, V1073 Cyg, HL Dra, AK Her, VW LMi, V566 Oph, TV UMi and AG Vir. By this
contribution, the DDO program has reached the point of 100 published radial
velocity orbits. The radial velocities have been determined using an improved
fitting technique which uses rotational profiles to approximate individual
peaks in broadening functions.
  Three systems, ET Boo, VW LMi and TV UMi, were found to be quadruple while AG
Vir appears to be a spectroscopic triple. ET Boo, a member of a close visual
binary with $P_{vis} = 113$ years, was previously known to be a multiple
system, but we show that the second component is actually a close,
non-eclipsing binary. The new observations enabled us to determine the
spectroscopic orbits of the companion, non-eclipsing pairs in ET Boo and VW
LMi. The particularly interesting case is VW LMi, where the period of the
mutual revolution of the two spectroscopic binaries is only 355 days.
  While most of the studied eclipsing pairs are contact binaries, ET Boo is
composed of two double-lined detached binaries and HL Dra is single-lined
detached or semi-detached system. Five systems of this group were observed
spectroscopically before: TX Cnc, V1073 Cyg, AK Her (as a single-lined binary),
V566 Oph, AG Vir, but our new data are of much higher quality than the previous
studies.


title: WMAP 3-year polarization data: Implications for the reionization history

abstract:
  We show that the delay of structure formation can not fully account for the
reduction of electron optical depth from WMAP1 to WMAP3 when the radiative
transfer effects and feedback mechanisms are took into account in computing the
reionization history of the Universe. We also show that a PopIII stellar
cluster with a mass of 80Mo and a heavy Larson initial mass function has an
ionizing efficiency high enough to account for WMAP3 results, while in the case
of WMAP1, a higher stellar mass of 1000Mo was required.


title:
A Spitzer Infrared Spectrograph Survey of Warm Molecular Hydrogen in
  Ultra-luminous Infrared Galaxies

abstract:
  We have conducted a survey of Ultra-luminous Infrared Galaxies (ULIRGs) with
the Infrared Spectrograph on the Spitzer Space Telescope, obtaining spectra
from 5.0-38.5um for 77 sources with 0.02<z <0.93. Observations of the pure
rotational H2 lines S(3) 9.67um, S(2) 12.28um, and S(1) 17.04um are used to
derive the temperature and mass of the warm molecular gas. We detect H2 in 77%
of the sample, and all ULIRGs with F(60um)>2Jy. The average warm molecular gas
mass is ~2x10^8solar-masses. High extinction, inferred from the 9.7um silicate
absorption depth, is not observed along the line of site to the molecular gas.
The derived H2 mass does not depend on F(25um)/F(60um), which has been used to
infer either starburst or AGN dominance. Similarly, the molecular mass does not
scale with the 25 or 60um luminosities. In general, the H2 emission is
consistent with an origin in photo-dissociation regions associated with star
formation. We detect the S(0) 28.22um emission line in a few ULIRGs. Including
this line in the model fits tends to lower the temperature by ~50-100K,
resulting in a significant increase in the gas mass. The presence of a cooler
component cannot be ruled out in the remainder of our sample, for which we do
not detect the S(0) line. The measured S(7) 5.51um line fluxes in six ULIRGs
implies ~3x10^6 solar-masses of hot (~1400K) H2. The warm gas mass is typically
less than 1% of the cold gas mass derived from CO observations.


title: Systematic Survey of Extended Lyman-alpha Sources over z~3-5

abstract:
  Spatially extended Ly-alpha sources which are faint and compact in coninuum
are candidates for extremely young galaxies (age of ~<10e+7 yrs) at high
redshifts. We carried out a systematic survey for extended Ly-alpha sources,
using deep intermediate-band imaging data taken with the Suprime-Cam on the
Subaru Telescope. Our survey covers a field of view of 33' * 25' and a redshift
range of 3.24<z<4.95, down to a Ly-alpha flux of ~1e-17 ergs/cm^2/s. We
identified 41 extended Ly-alpha sources. The redshift distribution of these
sources shows that this kind of objects are common in the early universe over
the surveyed redshift range. The identified objects have typical sizes of
\~10-15 kpc and luminosities of ~10^42 ergs/s. Follow-up spectroscopy made for
7 of the 41 objects showed that our sample suffers from little contamination.
All 7 objects have large equivalent widths of Ly-alpha emission line, all but
one exceeding 240A in the rest frame. The large equivalent widths suggest that
their extended Ly-alpha emissions are unlikely to be due to normal starbursts,
but possibly originated from very young galaxies. All 41 objects in our sample
have much smaller Ly-alpha luminosities than the two Ly-alpha Blobs (LABs)
found by Steidel et al. (2000) in spite of our much larger survey volume. This
suggests that large and luminous extended Ly-alpha objects like the two LABs
are very rare and are clustered in overdense regions.


title: Wide-field Corrector for a Gregory Telescope

abstract:
  A form of prime focus corrector for the Gregory system is proposed that
provides the sub-arcsecond field of view up to 3 degrees in diameter for the
spectral range 0.35-0.90 microns. The corrector includes five lenses made of
same glass (fused silica is preferable). The distinctive feature of the
corrector consists in dissimilar use of the central and edge zones of a front
lens disposed in the exit pupil of a two-mirror system.
  As an example, the f/1.9 telescope is considered with the 6.5-m aperture and
the total length 8.8~m. Its primary and secondary mirrors are pure ellipsoids
close to concave paraboloid and concave sphere, respectively. In the basic
configuration, all surfaces of the corrector are spherical. The diameter of a
star image D_{80} varies from 0''.25 on the optical axis up to 0''.50 at the
edge of the 2.3-deg field. Only slightly worse images shows spherical corrector
for the 2.4-deg field of view. The fraction of vignetted rays grows on 1.7%
from the center of field to its edges. Aspherization of some lens surfaces
allows to reach sub-arcsecond images in the field of 3.0 in diameter.


title: Limit on the Neutrino Mass from the WMAP Three Year Data

abstract:
  We derive an upper limit on the neutrino mass from the WMAP three-year data
alone by employing a deterministic minimisation method based on a grid search
in multi-parameter space. Assuming the flat LCDM model with power-law adiabatic
perturbations, we find the sum of m_nu < 2.0 eV in agreement with the result of
the WMAP team. This result, the limit being nearly the same as that from the
WMAP first-year data, means that the fundamental limit on the neutrino mass
obtainable from the cosmic microwave background alone is already nearly met, as
anticipated from the previous analysis. We also clarify the role of the
polarisation data in deriving the limit on the neutrino mass.


title: Diffuse light and building history of the galaxy cluster Abell 2667

abstract:
  We have searched for diffuse intracluster light in the galaxy cluster Abell
2667 (z=0.233) from HST images in three filters. We have applied to these
images an iterative multi-scale wavelet analysis and reconstruction technique,
which allows to subtract stars and galaxies from the original images. We detect
a zone of diffuse emission south west of the cluster center (DS1), and a second
faint object (ComDif), within DS1. Another diffuse source (DS2) may be
detected, at lower confidence level, north east of the center. These sources of
diffuse light contribute to 10-15% of the total visible light in the cluster.
Whether they are independent entities or are part of the very elliptical
external envelope of the central galaxy remains unclear. VLT VIMOS integral
field spectroscopy reveals a faint continuum at the positions of DS1 and ComDif
but do not allow to compute a redshift. A hierarchical substructure detection
method reveals the presence of several galaxy pairs and groups defining a
similar direction as the one drawn by the DS1-central galaxy-DS2 axis. The
analysis of archive XMM-Newton and Chandra observations shows X-ray emission
elongated in the same direction. The X-ray temperature map shows the presence
of a cool core, a broad cool zone stretching from north to south and hotter
regions towards the north east, south west and north west. This possibly
suggests shock fronts along these directions produced by infalling material.
These various data are consistent with a picture in which diffuse sources are
concentrations of tidal debris and harassed matter expelled from infalling
galaxies by tidal stripping and undergoing an accretion process onto the
central cluster galaxy; as such, they are expected to be found along the main
infall directions.


title: LP 714-37: A wide pair of ultracool dwarfs actually is a triple

abstract:
  LP 714-37 was identified by Phan-Bao et al. (2005) as one of the very few
wide pairs of very low mass (VLM) stars known to date, with a separation of 33
AU. Here we present adaptive optics imaging which resolves the secondary of the
wide pair into a tighter binary, with a projected angular separation of 0.36
arcsec, or 7 AU. The estimated spectral types of LP 714-37B and LP 714-37C are
M8.0 and M8.5. We discuss the implications of this finding for brown dwarf
formation scenarios.


title: Spitzer-IRS Observations of FU Orionis Objects

abstract:
  We present 5-35 $\mu$m spectra, taken with the Infrared Spectrograph (IRS) on
the Spitzer Space Telescope, of five FU Orionis objects: FU Ori, V1515 Cyg,
V1057 Cyg, BBW 76, and V346 Nor. All but V346 Nor reveal amorphous silicate
grains in emission at 10 $\mu$m and 20 $\mu$m, and show water-vapor absorption
bands at 5.8 and 6.8 $\mu$m and SiO or possibly methane absorption at 8 $\mu$m.
These absorption features closely match these bands in model stellar
photospheres -- signs of the gaseous photospheres of the inner regions of these
objects' accretion disks. The continuum emission at 5-8 $\mu$m is also
consistent with such disks, and, for FU Orionis and BBW 76, longer-wavelength
emission may be fit by a model which includes moderate disk flaring. V1057 Cyg
and V1515 Cyg have much more emission at longer wavelengths than the others,
perhaps evidence of substantial remnant of their natal, infalling envelopes.


title:
Features in Dark Energy Equation of State and Modulations in the Hubble
  Diagram

abstract:
  We probe the time dependence of the dark energy equation of state (EOS) in
light of three-year WMAP (WMAP3) and the combination with other tentative
cosmological observations from galaxy clustering (SDSS) and Type Ia Supernova
(SNIa). We mainly focus on cases where the EOS is oscillating or with local
bumps. By performing a global analysis with the Markov Chain Monte Carlo (MCMC)
method, we find the current observations, in particular the WMAP3 + SDSS data
combination, allow large oscillations of the EOS which can leave oscillating
features on the (residual) Hubble diagram, and such oscillations are
potentially detectable by future observations like SNAP, or even by the
CURRENTLY ONGOING SNIa observations. Local bumps of dark energy EOS can also
leave imprints on CMB, LSS and SNIa. In cases where the bumps take place at low
redshifts and the effective EOS are close to -1, CMB and LSS observations
cannot give constraints on such possibilities. However, geometrical
observations like (future) SNIa can possibly detect such features. On the other
hand when the local bumps take place at higher redshifts beyond the
detectability of SNIa, future precise observations like Gamma-ray bursts, CMB
and LSS may possibly detect such features. In particular, we find that
bump-like dark energy EOS on high redshifts might be responsible for the
features of WMAP on ranges l \sim 30-50, which is interesting and deserves
addressing further.


title:
Inflation after WMAP3: Confronting the Slow-Roll and Exact Power Spectra
  with CMB Data

abstract:
  The implications of the WMAP (Wilkinson Microwave Anisotropy Probe) third
year data for inflation are investigated using both the slow-roll approximation
and an exact numerical integration of the inflationary power spectra including
a phenomenological modelling of the reheating era. At slow-roll leading order,
the constraints epsilon_1 < 0.022 and -0.07 < epsilon_2 < 0.07 are obtained at
95% CL (Confidence Level) implying a tensor-to-scalar ratio r_10 < 0.21 and a
Hubble parameter during inflation H/Mpl < 1.3 x 10^(-5). At next-to-leading
order, a tendency for epsilon_3 > 0 is observed. With regards to the exact
numerical integration, large field models, V(phi) proportional to phi^p, with p
> 3.1 are now excluded at 95% CL. Small field models, V(phi) proportional to
1-(phi/mu)^p, are still compatible with the data for all values of p. However,
if mu/Mpl < 10 is assumed, then the case p = 2 is slightly disfavoured. In
addition, mild constraints on the reheating temperature for an extreme equation
of state w_reh = -1/3 are found, namely T_reh > 2 TeV at 95% CL. Hybrid models
are disfavoured by the data, the best fit model having Delta chi^2 = +5 with
two extra parameters in comparison with large field models. Running mass models
remain compatible, but no prior independent constraints can be obtained.
Finally, superimposed oscillations of trans-Planckian origin are studied. The
vanilla slow-roll model is still the most probable one. However, the overall
statistical weight in favour of superimposed oscillations has increased in
comparison with the WMAP first year data, the amplitude of the oscillations
satisfying 2|x|sigma_0 < 0.76 at 95% CL. The best fit model leads to an
improvement of Delta chi^2 = -12 for three extra parameters. Moreover, compared
to other oscillatory patterns, the logarithmic shape is favoured.


title: Accretion processes in AGN: The X-ray View

abstract:
  We discuss constraints on the physics of the inner accretion disk, as well as
the properties of the black hole itself, that can be derived by a detailed
examination of the relativistically broadened spectral features (especially the
fluorescent iron line) in the Seyfert galaxy MCG-6-30-15. To begin with, we
show that spectral models which purport to eliminate the broad iron line in
MCG-6-30-15 by invoking a moderately high ionization absorber are ruled out by
recent high-resolution spectra from the Chandra High Energy Transmission
Gratings. We then discuss the comparison of XMM-Newton data with accretion disk
models. The "standard'' black hole disk model of Novikov, Page and Thorne
supplemented by the so-called local corona assumption fails to produce
sufficient broadening; this indicates that the real accretion disk in
MCG-6-30-15 has significantly more centrally concentrated pattern of X-ray
irradiation that predicted by this model. We discuss two possible resolutions.
Firstly, the inner disk may be energized from torques imposed by magnetic
connections between the disk-proper and either the plunging region or the
rotating event horizon itself. Secondly, X-ray emission from a high-latitude
source (such as would be the case of the X-ray source is actually the base of a
jet) would be gravitationally focused onto the central portions of the disk. We
discuss how spectral variability may be used to examine these possibilities and
highlight the still outstanding mystery concerning the anti-correlation between
the iron line equivalent width and relative normalization of the Compton
reflection hump. We end with a few words about the exciting future of these
studies in the future era of Constellation-X and LISA.


title: Detecting dark matter in electromagnetic field penetration experiments

abstract:
  Dark matter in the form of particles from a hidden mirror sector has recently
been proposed as an explanation for the DAMA annual modulation signal. Here one
assumes that there exists a small mixing between photons and mirror photons. We
show that dark matter with this property can also be detected in
electromagnetic field penetration experiments. Such experiments can be used to
measure the speed and direction of the dark matter halo wind, the local
density, the temperature, and the strength of the photon-mirror photon mixing
interaction. An additional result would be a significant improvement of the
upper limit on the photon mass.


title:
The DEEP Groth Strip Survey VI. Spectroscopic, Variability, and X-ray
  Detection of AGN

abstract:
  We identify active galactic nuclei (AGN) in the Groth-Westphal Survey Strip
(GSS) using the independent and complementary selection techniques of optical
spectroscopy and photometric variability. We discuss the X-ray properties of
these AGN using Chandra/XMM data for this region. From a sample of 576 galaxies
with high quality spectra we identify 31 galaxies with AGN signatures. Seven of
these have broad emission lines (Type 1 AGNs). We also identify 26 galaxies
displaying nuclear variability in HST WFPC2 images of the GSS separated by ~7
years. The primary overlap of the two selected AGN samples is the set of
broad-line AGNs, of which 80% appear as variable. Only a few narrow-line AGNs
approach the variability threshold. The broad-line AGNs have an average
redshift of z~1.1 while the other spectroscopic AGNs have redshifts closer to
the mean of the general galaxy population (z~0.7). Eighty percent of the
identified broad-line AGNs are detected in X-rays and these are among the most
luminous X-ray sources in the GSS. Only one narrow-line AGN is X-ray detected.
Of the variable nuclei galaxies within the X-ray survey, 27% are X-ray
detected. We find that 1.9+/-0.6% of GSS galaxies to V=24 are broad-line AGNs,
1.4+/-0.5% are narrow-line AGNs, and 4.5+/-1.4% contain variable nuclei. The
fraction of spectroscopically identified BLAGNs and NLAGNs at z~1 reveals a
marginally significant increase of 1.3+/-0.9% when compared to the local
population.


title: Using cosmology to constrain the topology of hidden dimensions

abstract:
  A four-dimensional universe, arising from a flux compactification of Type IIB
string theory, contains scalar fields with a potential determined by
topological and geometric parameters of the internal -hidden- dimensions. We
show that inflation can be realized via rolling towards the large internal
volume minima that are generic in these scenarios, and we give explicit
formulae relating the microscopic parameters (e.g., the Euler number of the
internal space) to the cosmological observables (e.g., the spectral index). We
find that the tensor-to-scalar ratio, the running of the spectral index, and
the potential energy density at the minimum are related by consistency
relations and are exponentially small in the number of e-foldings. Further,
requiring that these models arise as low-energy limits of string theory
eliminates most of them, even if they are phenomenologically valid. In this
context, this approach provides a strategy for systematically falsifying
stringy inflation models.


title: Predictions for a planet just inside Fomalhaut's eccentric ring

abstract:
  We propose that the eccentricity and sharpness of the edge of Fomalhaut's
disk are due to a planet just interior to the ring edge. The collision
timescale consistent with the disk opacity is long enough that spiral density
waves cannot be driven near the planet. The ring edge is likely to be located
at the boundary of a chaotic zone in the corotation region of the planet. We
find that this zone can open a gap in a particle disk as long as the collision
timescale exceeds the removal or ejection timescale in the zone. We use the
slope measured from the ring edge surface brightness profile to place an upper
limit on the planet mass. The removal timescale in the chaotic zone is used to
estimate a lower limit. The ring edge has eccentricity caused by secular
perturbations from the planet. These arguments imply that the planet has a mass
between that of Neptune and that of Saturn, a semi-major axis of approximately
119 AU and longitude of periastron and eccentricity, 0.1, the same as that of
the ring edge.


title: The Formation Histories of Metal-Rich and Metal-Poor Globular Clusters

abstract:
  This review presents the results of ongoing studies of the formation
histories of metal-poor and metal-rich globular clusters and their host
galaxies. I first discuss the strong observational evidence that the globular
cluster systems of most elliptical galaxies have bimodal metallicity
distributions. I then focus on new results for metal-poor and metal-rich
globular cluster systems. Metal-poor globular clusters are often associated
with early structure formation, and I review new constraints on their formation
epoch based on the ``bias'' of the number of metal-poor clusters with host
galaxy mass. For metal-rich globular clusters, I discuss new results from
ongoing optical to near-infrared photometric studies which both confirm an
intermediate-age population in NGC 4365 and generally reveal a variety of
formation histories for now quiescent ellipticals.


title: Dynamics of Mesoscale Magnetic Field in Diffusive Shock Acceleration

abstract:
  We present a theory for the generation of mesoscale ($kr_{g}\ll 1$, where
$r_{g}$ is the cosmic ray gyroradius) magnetic fields during diffusive shock
acceleration. The decay or modulational instability of resonantly excited
Alfven waves scattering off ambient density perturbations in the shock
environment naturally generates larger scale fields. For a broad spectrum of
perturbations, the physical mechanism of energy transfer is random refraction,
represented by diffusion of Alfven wave packet in $k-$space. The scattering
field can be produced directly by the decay instability or by the Drury
instability, a hydrodynamic instability driven by the cosmic ray pressure
gradient. This process is of interest to acceleration since it generates waves
of longer wavelength, and so enables the confinement and acceleration of higher
energy particles. This process also limits the intensity of resonantly
generated turbulent magnetic field on $r_{g}$ scales.


title:
Measurement of Orbital Decay in the Double Neutron Star Binary PSR
  B2127+11C

abstract:
  We report the direct measurement of orbital period decay in the double
neutron star pulsar system PSR B2127+11C in the globular cluster M15 at the
rate of $(-3.95 \pm 0.13) \times 10^{-12}$, consistent with the prediction of
general relativity at the $\sim 3 %$ level. We find the pulsar mass to be $m_p
= (1.358 \pm 0.010) M_\odot$ and the companion mass $m_c = (1.354 \pm 0.010)
M_\odot$. We also report long-term pulse timing results for the pulsars PSR
B2127+11A and PSR B2127+11B, including confirmation of the cluster proper
motion.


title:
A radio-emitting outflow in the quiescent state of A0620-00:
  implications for modelling low-luminosity black hole binaries

abstract:
  Deep observations with the Very Large Array of A0620-00, performed in 2005
August, resulted in the first detection of radio emission from a black hole
binary at X-ray luminosities as low as 10^{-8.5} times the Eddington limit. The
measured radio flux density, of 51 \pm 7 microJy at 8.5 GHz, is the lowest
reported for an X-ray binary system so far, and is interpreted in terms of
partially self-absorbed synchrotron emission from outflowing plasma. Making use
of the estimated outer accretion rate of A0620-00 in quiescence, we demonstrate
that the outflow kinetic power must be energetically comparable to the total
accretion power associated with such rate, if it was to reach the black hole
with the standard radiative efficiency of 10 per cent. This favours a model for
quiescence in which a radiatively inefficient outflow accounts for a sizable
fraction of the missing energy, and, in turn, substantially affects the overall
dynamics of the accretion flow. Simultaneous observations in the X-ray band,
with Chandra, confirm the validity of a non-linear radio/X-ray correlation for
hard state black hole binaries down to low quiescent luminosities, thereby
contradicting some theoretical expectations. Taking the mass term into account,
the A0620-00 data lie on the extrapolation of the so called Fundamental Plane
of black hole activity, which has thus been extended by more than 2 orders of
magnitude in radio and X-ray luminosity. With the addition of the A0620-00
point, the plane relation provides an empirical proof for the scale-invariance
of the jet-accretion coupling in accreting black holes over the entire
parameter space observable with current instrumentation.


title:
Evolutionary Implications from SDSSJ085338.27+033246.1: A Spectacular N
  arrow-Line Seyfert 1 Galaxy with Young Post-starburst

abstract:
  We analyze the physical properties of post-starburst AGN SDSS
J085338.27+033246.1 according to its optical spectrum and discuss its
implications on AGN's evolution. The spectra PCA method is developed to extract
emission lines and absorption features from the total light spectrum. The
emission-line analysis indicates that the object can be classified as a NLS1
with FeII/H$\beta_{\rm{B}}=2.4\pm0.2$, large Eddington ratio ($\sim0.34$),
small black hole mass ($\sim1.1\times10^{7}M_{\odot}$) and intermediately
strong radio emission. A simple SSP model indicates that the absorption
features are reproduced by a $\sim$100 Myr old starburst with a mass of
$\sim7\times10^{9}M_{\odot}$ rather well. The current SFR
$\sim3.0M_{\odot}\rm{yr^{-1}}$ inferred from the [OII] emission is much smaller
than the past average SFR$\sim70M_{\odot}\rm{yr^{-1}}$, however. The line ratio
diagnosis using the BPT diagrams indicates that the narrow emission lines are
almost entirely emitted from HII regions. We further discuss a possible
evolutionary path that links AGN and starburst phenomena.


title: What is the Role of Neutrinos in Shaping the Universe?

abstract:
  I review various aspects of the role neutrinos have played in shaping various
cosmological observables: the nature of large scale structure, observed
fluctuations in the CMB, the nature of matter, and the shape of things to come.
(Invited review lecture III International Workshop on NO-VE, Venice, 2006)


title: A Library of Lick/IDS Indices for Binary Stellar Populations

abstract:
  Using EPS we present 13 refined Lick/IDS absorption-line indices for an
extensive set of instantaneous-burst binary stellar populations (BSPs) at high
resolution (0.3 \AA) of various age and metallicity (1-15Gyr, 0.004-0.03), and
38 indices at intermediate resolution (3 \AA). These indices are obtained by
two methods: (1) obtain them by using the empirical fitting functions (FFs
method); (2) measure them directly from the synthetic spectra (DC method).
Together with our previous paper a database of Lick/IDS spectral
absorption-line indices for BSPs at high and intermediate resolutions is
provided. This set of indices includes 21 indices of Worthey et al., four
Balmer indices defined by Worthey & Ottaviani and 13 indices with the new
passband definitions of Trager et al. The full set of synthetic indices and the
integrated pseudo-continuum are listed in the Appendix, which is only available
online or from our website (http://www.ast9. com/), or on request from the
first author. Moreover, the ISEDs can be obtained from our website.
  We compare the synthetic Lick/IDS indices obtained by FFs method and those by
DC method, and find that the discrepancies are significant: Ca4455 (index 6),
Fe4668 (8), Mg_b (13), Fe5709 (17), NaD (19), TiO_1 (20) and TiO_2 (21, except
for Z=0.02) in the W94 system, Ca4455^T (6^T), C_2 4668^T (8^T), NaD^T (19^T),
TiO_1^T (20^T) and TiO_2^T (21^T, except for Z=0.02) in the T98 system obtained
by DC method are less (bluer) than the corresponding ones obtained by FFs
method for all metallicities. Ca4227 (index 3), Fe5782 (18),Ca4227^T (3^T) and
Fe5782^T (18^T) are greater at Z=0.03 and become to be bluer at Z=0.004,
Fe5709^T (17^T) index is less at Z=0.03 and becomes to be redder at Z=0.004
than the corresponding ones obtained by FFs method.


title:
A strong $\ddot{\nu} - \dot{\nu}$ correlation in radio pulsars with
  implications for torque variations

abstract:
  We present an analysis of the spin-down parameters for 131 radio pulsars for
which $\ddot\nu$ has been well determined. These pulsars have characteristic
ages ranging from $10^{3} - 10^{8}$ yr and spin periods in the range 0.4--30 s;
nearly equal numbers of pulsars have $\ddot\nu>0$ as $\ddot\nu<0$. We find a
strong correlation of $\ddot\nu$ with $\dot{\nu}$, {\em independent of the sign
of} $\ddot\nu$. We suggest that this trend can be accounted for by small,
stochastic deviations in the spin-down torque that are directly proportional
(in magnitude) to the spin-down torque.


title: Dark energy in motion

abstract:
  Recent large-scale peculiar velocity surveys suggest that large matter
volumes could be moving with appreciable velocity with respect to the CMB rest
frame. If confirmed, such results could conflict with the Cosmological
Principle according to which the matter and CMB rest frames should converge on
very large scales. In this work we explore the possibility that such large
scale bulk flows are due, not to the motion of matter with respect to the CMB,
but to the flow of dark energy with respect to matter. Indeed, when dark energy
is moving, the usual definition of the CMB rest frame as that in which the CMB
dipole vanishes is not appropriate. We find instead that the dipole vanishes
for observers at rest with respect to the cosmic center of mass, i.e. in motion
with respect to the background radiation.


title: FU Orionis - The MIDI/VLTI Perspective

abstract:
  We present the first mid-infrared interferometric measurements of FU Orionis.
We clearly resolve structures that are best explained with an optically thick
accretion disk. A simple accretion disk model fits the observed SED and
visibilities reasonably well and does not require the presence of any
additional structure such as a dusty envelope. The inclination and also the
position angle of the disk can be constrained from the multibaseline
interferometric observations. Our disk model is in general agreement with most
published near-infrared interferometric measurements. From the shape and
strength of the 8-13 micrometer spectrum the dust composition of the accretion
disk is derived for the first time. We conclude that most dust particles are
amorphous and already much larger than those typically observed in the ISM.
Although the high accretion rate of the system provides both, high temperatures
out to large radii and an effective transport mechanism to distribute
crystalline grains, we do not see any evidence for crystalline silicates
neither in the total spectrum nor in the correlated flux spectra from the inner
disk regions. Possible reasons for this non-detection are mentioned. All
results are discussed in context with other high-spatial resolution
observations of FU Ori and other FU Ori objects. We also address the question
whether FU Ori is in a younger evolutionary stage than a classical TTauri star.


title:
Chandra/HETGS Observations of the Capella System: the Primary as a
  Dominating X-ray Source

abstract:
  Using the Chandra/High Energy Transmission Grating Spectrometer (hereafter
HETGS) we have detected Doppler motion of Capella's X-ray emission lines in the
6 -- 25AA wave-band. The observed motion follows the expected orbital motion of
Capella's primary. This finding implies that the primary G8 III star, not the
secondary G1 III star in the Hertzsprung gap, has been the dominant source of
hot 10^{6.8} -- 10^{7}K plasma at least in the last six years. In addition, the
results demonstrate the long-term stability of the HETGS and demonstrate small
uncertainties of 25 and 33 km/s in the velocity determination with the HEG and
MEG, respectively.


title: Power-laws f(R) theories are cosmologically unacceptable

abstract:
  In a recent paper [1] (PRL 98,131302,2007) we have shown that f(R)=R + mu
R^{n} modified gravity dark energy models are not cosmologically viable because
during the matter era that precedes the accelerated stage the cosmic expansion
is given by a sim t^{1/2} rather than a sim t^{2/3}, where a is a scale factor
and t is the cosmic time. A recent work [2] (PLB 639,135-143,2006) by
Capozziello et al. criticised our results presenting some apparent
counter-examples to our claim in f(R)= mu R^{n} models. We show here that those
particular R^{n} models can produce an expansion as a sim t^{2/3} but this does
not connect to a late-time acceleration. Hence, though acceptable f(R) dark
energy models may exist, the R^{n} models presented in Capozziello et al. are
not cosmologically viable, confirming our previous results in Ref. [1].


title: Baryonic loading and e^+e^- rate equation in GRB sources

abstract:
  The expansion of the electron-positron plasma in the GRB phenomenon is
compared and contrasted in the treatments of Meszaros, Laguna and Rees, of
Shemi, Piran and Narayan, and of Ruffini et al. The role of the correct
numerical integration of the hydrodynamical equations, as well as of the rate
equation for the electron-positron plasma loaded with a baryonic mass, are
outlined and confronted for crucial differences.


title: CO and CH3OH observations of the BHR71 outflows with APEX

abstract:
  Context : Highly-collimated outflows are believed to be the earliest stage in
outflow evolution, so their study is essential for understanding the processes
driving outflows. The BHR71 Bok globule is known to harbour such a
highly-collimated outflow, which is powered by a protostar belonging to a
protobinary system. Aims : We aimed at investigating the interaction of
collimated outflows with the ambient molecular cloud by using molecular
tracers. Methods : We mapped the BHR71 highly-collimated outflow in CO(3-2)
with the APEX telescope, and observed several bright points of the outflow in
the molecular transitions CO(4-3), 13CO(3-2), C18O(3-2), and CH3OH(7-6). We use
an LVG code to characterise the temperature enhancements in these regions.
Results : In our CO(3-2) map, the second outflow driven by IRS2, which is the
second source of the binary system, is completely revealed and shown to be
bipolar. We also measure temperature enhancements in the lobes. The CO and
methanol LVG modelling points to temperatures between 30 and 50K in the IRS1
outflow, while the IRS2 outflow seems to be warmer (up to 300K).


title:
Shock Breakout in Type Ibc Supernovae and Application to GRB 060218/SN
  2006aj

abstract:
  Recently, a soft black-body component was observed in the early X-ray
afterglow of GRB 060218, which was interpreted as shock breakout from the thick
wind of the progenitor Wolf-Rayet (WR) star of the underlying Type Ic SN
2006aj. In this paper we present a simple model for computing the
characteristic quantities (including energy, temperature, and time-duration)
for the transient event from the shock breakout in Type Ibc supernovae produced
by the core-collapse of WR stars surrounded by dense winds. In contrast to the
case of a star without a strong wind, the shock breakout occurs in the wind
region rather than inside the star, caused by the large optical depth in the
wind. We find that, for the case of a WR star with a dense wind, the total
energy of the radiation generated by the supernova shock breakout is larger
than that in the case of the same star without a wind by a factor > 10. The
temperature can be either hotter or cooler, depending on the wind parameters.
The time-duration is larger caused by the increase in the effective radius of
the star due to the presence of a thick wind. Then, we apply the model to GRB
060218/SN 2006aj. We show that, to explain both the temperature and the total
energy of the black-body component observed in GRB 060218 by the shock
breakout, the progenitor WR star has to have an unrealistically large core
radius (the radius at optical depth of 20), larger than 100 Rsun. In spite of
this disappointing result, our model is expected to have important applications
to the observations on Type Ibc supernovae in which the detection of shock
breakout will provide important clues to the progenitors of SNe Ibc.


title: Inflation is the generic feature of phantom field-not the big-rip

abstract:
  A class of solutions for phantom field corresponding to a generalized
k-essence lagrangian has been presented, employing a simple method which
provides the scope to explore many such. All the solutions having dynamical
state parameter are found to touch the magic line w = -1, asymptotically. The
solutions with constant equation of state can represent phantom, quitessence or
an ordinary scalar field cosmologies depending on the choice of a couple of
parameters of the theory. For w approximately equal to -1, quintessence and
phantom models are indistinguishable through the Hubble parameter. Finally,
inflation rather than big-rip has been found to be the generic feature of
phantom cosmology.


title:
Deep Impact Mission to Tempel 1 Favours New Explosive Cosmogony of
  Comets

abstract:
  The assumption that short-period (SP) comets are fragments of massive icy
envelopes of Ganymede-like bodies saturated by products of ice electrolysis
that underwent global explosions provides a plausible explanation of all known
manifestations of comets, including the jet character of outflows, the presence
of ions in the vicinity of the nucleus, the bursts and splitting of cometary
nuclei, etc., with solar radiation initiating burning of the products of
electrolysis in the nucleus. As shown persuasively by numerical simulation
carried out in hydrodynamic approximation, the shock wave initiated by the Deep
Impact (DI) impactor in the cometary ice saturated originally by the
electrolysis products 2H2 + O2 is capable of activating under certain
conditions exothermal reactions (of the type O2 + H2 + organics = H2O + CO +
HCN + other products of incomplete burning of organics including its light and
heavy pyrolyzed compounds, soot, etc.), which will slow down shock wave damping
(forced detonation) and increase many times the energy release. As a result,
the measured energetics of ejections and outflows from the crater have to
exceed the DI energetics. Analysis of different clusters of the DI experiment
data confirms these conclusions and expectations and thus it favours the
planetary origin of comets.


title: The magnetic nature of disk accretion onto black holes

abstract:
  Although disk accretion onto compact objects - white dwarfs, neutron stars,
and black holes - is central to much of high energy astrophysics, the
mechanisms which enable this process have remained observationally elusive.
Accretion disks must transfer angular momentum for matter to travel radially
inward onto the compact object. Internal viscosity from magnetic processes and
disk winds can in principle both transfer angular momentum, but hitherto we
lacked evidence that either occurs. Here we report that an X-ray-absorbing wind
discovered in an observation of the stellar-mass black hole binary GRO J1655-40
must be powered by a magnetic process that can also drive accretion through the
disk. Detailed spectral analysis and modeling of the wind shows that it can
only be powered by pressure generated by magnetic viscosity internal to the
disk or magnetocentrifugal forces. This result demonstrates that disk accretion
onto black holes is a fundamentally magnetic process.


title: Discovery of the low-energy cutoff in a powerful giant radio galaxy

abstract:
  The lobes of radio galaxies and quasars, fed by jets and hotspots, represent
a significant, and currently ill-constrained, source of energy input into the
inter-galactic medium (IGM). How much energy is input into the IGM depends on
the minimum energy to which the power-law distribution of relativistic
particles is accelerated in the hotspots. This has hitherto been unknown to
within three orders of magnitude. We present direct evidence for the discovery
of this low-energy cutoff in the lobe of a Mpc-sized radio galaxy via the
existence of extended X-ray emission, inverse-Compton scattered from aged radio
plasma, and its separation by 80kpc from regions containing freshly accelerated
plasma from the hotspot. The low-energy cutoff of gamma ~ 10^4 in the hotspot
is higher than previously thought, but reconciles discrepancies with magnetic
field estimates which had been systematically lower than equipartition values.
The inverse Compton scattering of the spent synchrotron plasma is at the
expense of cosmic microwave background (CMB) photons; we comment on the
importance of such giant radio galaxies as contaminants of CMB anisotropies.


title:
Uncertainty on determining the dark energy equation of state due to the
  spatial curvature

abstract:
  We have studied the uncertainty on the determination of the dark energy
equation of state due to a non-vanishing spatial curvature by considering some
fundamental observables. We discussed the sensitivity of these observables to
the value and redshift history of the equation of state and the spatial
curvature and investigated whether these different observables are
complementary and can help to reduce the cosmic confusion.


title: Luminous superclusters: remnants from inflation

abstract:
  We derive the luminosity and multiplicity functions of superclusters compiled
for the 2dF Galaxy Redshift Survey, the Sloan Digital Sky Survey (Data Release
4), and for three samples of simulated superclusters. We find for all
supercluster samples Density Field (DF) clusters, which represent high-density
peaks of the class of Abell clusters, and use median luminosities/masses of
richness class 1 DF-clusters to calculate relative luminosity/mass functions.
We show that the fraction of very luminous (massive) superclusters in real
samples is more than tenfolds greater than in simulated samples. Superclusters
are generated by large-scale density perturbations which evolve very slowly.
The absence of very luminous superclusters in simulations can be explained
either by non-proper treatment of large-scale perturbations, or by some yet
unknown processes in the very early Universe.


title:
Observations of the recently discovered dwarf nova 1RXS J053234.9+624755
  during the 2005 March superoutburst

abstract:
  1RXS J053234.9+624755 is a recently discovered dwarf nova. We present CCD and
visual photometry during March 2005 of the first ever observed superoutburst in
this system


title: Photometric Variability of Be/X-ray-Pulsar Binaries in the SMC

abstract:
  We have studied the photometric variability of ten SMC Be/X-ray pulsars using
MACHO and OGLE-II data. For some of these systems we have found periodic
behavior, including orbital outbursts and/or nonradial pulsations (NRP) of the
Be star. For others we were unable to identify any clear photometric
periodicity, although their longterm light curves show significant structure.
We present periodograms, phase dispersion minimization (PDM) variances, and
folded light curves for the systems which exhibit periodic photometric
variability.


title: Detection of a 60 Degree-Long Dwarf Galaxy Debris Stream

abstract:
  We report on a 60 degree-long stream of stars, extending from Ursa Major to
Sextans, in the Sloan Digital Sky Survey. The stream is approximately 2 degrees
wide and is clearly distinct from the northern tidal arm of the Sagittarius
dwarf galaxy. The apparent width of the stream suggests a progenitor with a
size and mass similar to that of a dwarf galaxy. The stream is about 21 kpc
distant and appears to be oriented almost perpendicular to our line of sight.
The visible portion of the stream does not pass near any known dwarf galaxies,
though we cannot rule out that the stream may form the inner part of a known
dwarf galaxy's orbit. The most likely explanation is that the stream
constitutes the remains a dwarf galaxy that has been completely disrupted at
some point in the past. We also briefly report on the discovery of a diminutive
Galactic satellite which lies near the projected path of the new stream, but is
unlikely to be related to it.


title: An Investigation of Be/X-ray Pulsars with OGLE-III Data

abstract:
  We have studied five seasons of OGLE-III data for eight SMC Be/X-ray pulsars
for which no other survey data were available. We have determined orbital
periods for four of these binary systems, one of which also shows nonradial
pulsations. Optical identification of SMC X-2 is reconsidered, but no periods
were found for either of the two possible candidates.


title: A Catalog of Emission line profiles for Planetary Nebulae

abstract:
  Using the Cloudy_3D code (Morisset, this conference), we run a set of models
to build a catalog of emission line profiles of PNe. The goal is to cover the
main morphologies (spherical, ellipsoidal, bipolar, thin or thick shells) and
to compute profiles changing the orientation of the nebula, the expansion
velocity law (including or not turbulence), the position/size of the aperture.
The results is a huge set of profiles and PV-diagrams that can be compared to
observations as a help to derive morpho-kinematical properties of real objects.


title:
Unification scheme and the distribution of neutral gas in compact radio
  sources

abstract:
  We examine the consistency of HI properties with the unification scheme for
radio galaxies and quasars, and any correlation with the symmetry parameters
for a sample of CSS and GPS sources. In our sample, 15 out of 23 galaxies
exhibit 21-cm absorption as against 1 out of 9 quasars, which is broadly
consistent with the unification scheme. Also there is a tendency for the
detection rate as well as the column density for galaxies to increase with core
prominence, f_c, a statistical indicator of the orientation of the jet axis to
the line of sight. This can be understood in a scenario where radio sources are
larger than the scale of the circumnuclear HI disk so that the lines of sight
to the lobes at very large inclinations do not intersect the disk. The sources
in our sample also exhibit the known anti-correlation between HI column density
and source size. This suggests that small linear size, along with intermediate
values of core prominence, is a good recipe for detecting 21-cm absorption in
CSS and GPS objects. Some of the absorption could also be arising from clouds
which may have interacted with the radio jet. The HI column density and
velocity shift of the primary absorption component, however, show no dependence
on the degree of misalignment and the separation ratio of the radio sources.


title: Cloudy_3D, a new pseudo-3D photoionization code

abstract:
  We developed a new quick pseudo-3D photoionization code based on Cloudy (G.
Ferland) and IDL (RSI) tools. The code is running the 1D photoionization code
Cloudy various times, changing at each run the input parameters (e.g. inner
radius, density law) according to an angular law describing the morphology of
the object. Then a cube is generated by interpolating the outputs of Cloudy. In
each cell of the cube, the physical conditions (electron temperature and
density, ionic fractions) and the emissivities of lines are determined.
Associated tools (VISNEB and VELNEB_3D) are used to rotate the nebula and to
compute surface brightness maps and emission line profiles, given a velocity
law and taking into account the effect of the thermal broadening and eventually
the turbulence. Integrated emission line profiles are computed, given aperture
shapes and positions (seeing and instrumental width effects are included). The
main advantage of this tool is the short time needed to compute a model (a few
tens minutes).


title:
A search for kilogauss magnetic fields in white dwarfs and hot subdwarf
  stars

abstract:
  We present new results of a survey for weak magnetic fields among DA white
dwarfs with inclusion of some brighter hot subdwarf stars. We have detected
variable circular polarization in the Halpha line of the hot subdwarf star
Feige 34 (SP: sdO). From these data, we estimate that the longitudinal magnetic
field of this star varies from -1.1 +/- 3.2 kG to +9.6 +/- 2.6 kG, with a mean
of about +5 kG and a period longer than 2 h. In this study, we also confirm the
magnetic nature of white dwarf WD1105-048 and present upper limits of kilogauss
longitudinal magnetic fields of 5 brightest DA white dwarfs. Our data support
recent finding that 25% of white dwarfs have kilogauss magnetic fields. This
frequency also confirms results of early estimates obtained using the magnetic
field function of white dwarfs.


title:
Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions
  for GLAST

abstract:
  A study of the statistics of cosmological black-hole jet sources is applied
to EGRET blazar data, and predictions are made for GLAST. Black-hole jet
sources are modeled as collimated relativistic plasma outflows with radiation
beamed along the jet axis due to strong Doppler boosting. The comoving rate
density of blazar flares is assumed to follow a blazar formation rate (BFR),
modeled by analytic functions based on astronomical observations and fits to
EGRET data. The redshift and size distributions of gamma-ray blazars observed
with EGRET, separated into BL Lac object (BL) and flat spectrum radio quasar
(FSRQ) distributions, are fit with monoparametric functions for the
distributions of the jet Lorentz factor \Gamma, comoving directional power
l'_e, and spectral slope. A BFR factor ~10 x greater at z ~ 1 than at present
is found to fit the FSRQ data. A smaller comoving rate density and greater
luminosity of BL flares at early times compared to the present epoch fits the
BL data. Based on the EGRET observations, ~1000 blazars consisting of ~800
FSRQs and FR2 radio galaxies and ~200 BL Lacs and FR1 radio galaxies will be
detected with GLAST during the first year of the mission. Additional AGN
classes, such as hard-spectrum BL Lacs that were mostly missed with EGRET,
could add more GLAST sources. The FSRQ and BL contributions to the EGRET
gamma-ray background at 1 GeV are estimated at the level of ~10 - 15% and ~2 -
4%, respectively. EGRET and GLAST sensitivities to blazar flares are considered
in the optimal case, and a GLAST analysis method for blazar detection is
outlined.


title: Optimized supernova constraints on dark energy evolution

abstract:
  A model-independent method to study the possible evolution of dark energy is
presented. Optimal estimates of the dark energy equation of state w are
obtained from current supernovae data from Riess et al. (2004) following a
principal components approach. We assess the impact of varying the number of
piecewise constant estimates of w using a model selection method, the Bayesian
information criterion, and compare the most favored models with some
parametrizations commonly used in the literature. Although data seem to prefer
a cosmological constant, some models are only moderately disfavored by our
selection criterion: a constant w, w linear in the scale factor, w linear in
redshift and the two-parameter models introduced here. Among these, the models
we find by optimization are slightly preferred. However, current data do not
allow us to draw a conclusion on the possible evolution of dark energy.
Interestingly, the best fits for all varying-w models exhibit a w<-1 at low
redshifts.


title: Modelling of asymmetric nebulae. II. Line profiles

abstract:
  We present a tool, VELNEB_3D, which can be applied to the results of 3D
photoionization codes to generate emission line profiles, position-velocity
maps and 3D maps in any emission line by assuming an arbitrary velocity field.
  We give a few examples, based on our pseudo-3D photoionization code NEBU_3D
(Morisset, Stasinska and Pena, 2005) which show the potentiality and usefulness
of our tool. One example shows how complex line profiles can be obtained even
with a simple expansion law if the nebula is bipolar and the slit slightly
off-center. Another example shows different ways to produce line profiles that
could be attributed to a turbulent velocity field while there is no turbulence
in the model. A third example shows how, in certain circumstances, it is
possible to discriminate between two very different geometrical structures --
here a face-on blister and its ``spherical impostor'' -- when using appropriate
high resolution spectra. Finally, we show how our tool is able to generate 3D
maps, similar to the ones that can be obtained by observing extended nebulae
with integral field units.


title:
Constraints on the velocity profiles of galaxies from strong lensing
  statistics and semi-analytical modelling of galaxy formation

abstract:
  Semi-analytical models of galaxy formation can be used to predict the
evolution of the number density of early-type galaxies as a function of the
circular velocity at the virial radius, v_{c,vir}. Gravitational lensing
probability and separation distribution on the other hand are sensitive to the
velocity dispersion (or circular velocity) at about the effective radius. We
adopt the singular isothermal ellipsoid (SIE) lens model to estimate the
velocity dispersion at the effective radius. We use radio lenses from the
Cosmic Lens All-Sky Survey and the PMN-NVSS Extragalactic Lens Survey to study
how the velocity dispersions, \sigma_SIE, are related to v_{c,vir}. When we
include both the lensing probability and separation distribution as our lensing
constraints, we find \sigma_SIE /(200\kms) =
  [(1.17_{-0.26}^{+0.40}) v_{c,vir}/ (200\kms)]^{0.22^{+0.05}_{-0.04}} for
200\kms \la \sigma_SIE \la 260\kms; at \sigma_SIE = 200\kms, the ratio \sqrt{2}
\sigma_SIE / v_{c,vir} is about 1.65^{+0.57}_{-0.37} (68% CL) but decreases to
0.65_{-0.12}^{+0.15} (68% CL) for \sigma_SIE = 260\kms. These results are
consistent with those of Seljak (2002) obtained from galaxy-galaxy weak lensing
for galaxies of around L_*. However, our results clearly suggest that the ratio
must vary significantly as \sigma_SIE is varied and are marginally discrepant
with the Seljak results at \sigma_SIE = 260\kms. The scaling \sigma_SIE \propto
v_{c,vir}^{0.22\pm 0.05} is broadly consistent with those from galaxy
occupation statistics studies and the most recent galaxy-galaxy weak lensing
study. (Abridged)


title:
Keck Deep Fields. III. Luminosity-dependent Evolution of the Ultraviolet
  Luminosity and Star Formation Rate Densities at z~4, 3, and 2

abstract:
  We use the Keck Deep Fields UGRI catalog of z~4, 3, and 2 UV-selected
galaxies to study the evolution of the rest-frame 1700A luminosity density at
high redshift. The ability to reliably constrain the contribution of faint
galaxies is critical and our data do so as they reach to M*+2 even at z~4 and
deeper still at lower redshifts. We find that the luminosity density at high
redshift is dominated by the hitherto poorly studied galaxies fainter than L*,
and, indeed, the the bulk of the UV light in the high-z Universe comes from
galaxies in the luminosity range L=0.1-1L*. It is these faint galaxies that
govern the behavior of the total UV luminosity density. Overall, there is a
gradual rise in luminosity density starting at z~4 or earlier, followed by a
shallow peak or a plateau within z~3--1, and then followed by the well-know
plunge at lower redshifts. Within this total picture, luminosity density in
sub-L* galaxies evolves more rapidly at high redshift, z>~2, than that in more
luminous objects. However, this is reversed at lower redshifts, z<~1, a
reversal that is reminiscent of galaxy downsizing. Within the context of the
models commonly used in the observational literature, there seemingly aren't
enough faint or bright LBGs to maintain ionization of intergalactic gas even as
late as z~4. This is particularly true at earlier epochs and even more so if
the faint-end evolutionary trends we observe at z~3 and 4 continue to higher
redshifts. Apparently the Universe must be easier to reionize than some recent
studies have assumed. Nevertheless, sub-L* galaxies do dominate the total UV
luminosity density at z>~2 and this dominance further highlights the need for
follow-up studies that will teach us more about these very numerous but thus
far largely unexplored systems.


title: An Optically Dark GRB Observed by HETE-2: GRB 051022

abstract:
  GRB 051022 was detected at 13:07:58 on 22 October 2005 by HETE-2. The
location of GRB 051022 was determined immediately by the flight localization
system. This burst contains multiple pulses and has a rather long duration of
about 190 seconds. The detections of candidate X-ray and radio afterglows were
reported, whereas no optical afterglow was found. The optical spectroscopic
observations of the host galaxy revealed the redshift z = 0.8. Using the data
derived by HETE-2 observation of the prompt emission, we found the absorption
N_H = 8.8 -2.9/+3.1 x 10^22 cm^-2 and the visual extinction A_V = 49 -16/+17
mag in the host galaxy. If this is the case, no detection of any optical
transient would be quite reasonable. The absorption derived by the Swift XRT
observations of the afterglow is fully consistent with those obtained from the
early HETE-2 observation of the prompt emission. Our analysis implies an
interpretation that the absorbing medium could be outside external shock at R ~
10^16 cm, which may be a dusty molecular cloud.


title: OB Stars in the Solar Neighborhood II: Kinematics

abstract:
  Using the spatial classification method and the structural parameters
estimated for the Gould Belt (GB) and the local Galactic disk (LGD) from a
previous paper, we have evaluated spatial membership probabilities for a sample
of O and B stars from the Hipparcos catalogue (ESA 1997) with available proper
motions and radial velocity data. Thus being able to study the space velocity
fields of both systems, we conclude that the GB and the LGD present different
statistical distributions, both in the velocity space as well as in the phase
space. In the light of the existence of both systems we analyze different
kinematic aspects in the vicinity of the Sun, and we find the GB to be
responsible for the highly negative vertex deviation found for the OB stars in
the solar neighborhood. We also find that the GB sensibly alters the estimation
of Oort's constants in the Galactic disk; thus, in order to establish
comparisons with other kinematic studies based in older stellar populations, a
careful pruning of the GB members must be performed. Further analysis of the GB
velocity field and the moving groups that contribute to it suggest the
possibility that the GB can be the result of a chance superposition of moving
groups. We propose for future investigations the dynamical analysis of these
moving groups in order to probe the origin of the GB.


title: Dilute and Collapsed Phases of the Self-Gravitating Gas

abstract:
  The self-gravitating gas in thermal equilibrium is studied using a Newtonian
potential regularized at short distances. This short distance cutoff permits us
to obtain a complete description of the gas including its collapsed phase. We
give a field theory description of the N-body regularized self-gravitating gas
in the canonical ensemble.The corresponding functional integral is dominated in
the N -> infty limit by saddle points which provide a mean field description.
The well-known dilute solutions (isothermal spheres) are recovered. We find new
solutions which are regular in the regularized theory but become singular in
the zero cutoff limit. They describe collapsed configurations where the
particles are densely concentrated in a region of the size of the cutoff. These
collapsed solutions provide the absolute minimum of the free energy. We find
further new solutions which interpolate between the collapsed and the dilute
configurations and describe tunneling processes where the gas collapses. The
transition proba- bility for such collapse processes turns out to be extremely
small for large N. That is, the dilute solutions are in practice stable in the
regime where they are locally stable.

categories: astro-ph cond-mat.stat-mech gr-qc hep-th


title: A far-infrared molecular and atomic line survey of the Orion KL region

abstract:
  We have carried out a high spectral resolution line survey towards the Orion
Kleinmann-Low (KL) cluster from 44-188 um. The observations were taken with the
Long Wavelength Spectrometer (LWS) in Fabry-Perot mode, on board the Infrared
Space Observatory (ISO). A total of 152 lines are clearly detected and a
further 34 features are present as possible detections. The spectrum is
dominated by the molecular species H2O, OH and CO, along with [OI] and [CII]
lines from PDR or shocked gas and [OIII], [NIII] lines from the foreground M42
HII region. Several isotopic species, as well as NH3, are also detected. HDO
and H3O+ are tentatively detected for the first time in the far-infrared range
towards Orion-KL. A basic analysis of the line observations is carried out, by
comparing with previous measurements and published models and deriving
rotational temperatures and column densities in the case of the molecular
species. The complexity of the region requires more sophisticated models for
the interpretation of all the line observations.


title:
Diagnostics for specific PAHs in the far-IR: searching neutral
  naphthalene and anthracene in the Red Rectangle

abstract:
  Context. In the framework of the interstellar polycyclic aromatic
hydrocarbons (PAHs) hypothesis, far-IR skeletal bands are expected to be a
fingerprint of single species in this class. Aims. We address the question of
detectability of low energy PAH vibrational bands, with respect to spectral
contrast and intensity ratio with ``classical'' Aromatic Infrared Bands (AIBs).
Methods. We extend our extablished Monte-Carlo model of the photophysics of
specific PAHs in astronomical environments, to include rotational and
anharmonic band structure. The required molecular parameters were calculated in
the framework of the Density Functional Theory. Results. We calculate the
detailed spectral profiles of three low-energy vibrational bands of neutral
naphthalene, and four low-energy vibrational bands of neutral anthracene. They
are used to establish detectability constraints based on intensity ratios with
``classical'' AIBs. A general procedure is suggested to select promising
diagnostics, and tested on available Infrared Space Observatory data for the
Red Rectangle nebula. Conclusions. The search for single, specific PAHs in the
far-IR is a challenging, but promising task, especially in view of the
forthcoming launch of the Herschel Space Observatory.


title: Fine structure in the gamma-ray sky

abstract:
  The EGRET results for gamma-ray intensities in and near the Galactic Plane
have been analysed in some detail. Attention has been concentrated on energies
above 1 GeV and the individual intensities in a $4^\circ$ longitude bin have
been determined and compared with the large scale mean found from a nine-degree
polynomial fit.
  Comparison has been made of the observed standard deviation for the ratio of
these intensities with that expected from variants of our model. The basic
model adopts cosmic ray origin from supernova remnants, the particles then
diffusing through the Galaxy with our usual 'anomalous diffusion'. The variants
involve the clustering of SN, a frequency distribution for supernova explosion
energies, and 'normal', rather than 'anomalous' diffusion.
  It is found that for supernovae of unique energy, and our usual anomalous
diffusion, clustering is necessary, particularly in the Inner Galaxy. An
alternative, and preferred, situation is to adopt the model with a frequency
distribution of supernova energies. The results for the Outer Galaxy are such
that no clustering is required.


title:
VLT K-band spectroscopy of massive young stellar objects in
  (ultra-)compact HII regions

abstract:
  High-quality K-band spectra of strongly reddened point sources, deeply
embedded in (ultra-) compact HII regions, have revealed a population of 20
young massive stars showing no photospheric absorption lines, but sometimes
strong Br-gamma emission. The Br-gamma equivalent widths occupy a wide range
(from about 1 to over 100 A); the line widths of 100-200 km/s indicate a
circumstellar rather than a nebular origin. The K-band spectra exhibit one or
more features commonly associated with massive young stellar objects (YSOs)
surrounded by circumstellar material: a very red colour (J-K) > 2, CO bandhead
emission, hydrogen emission lines (sometimes doubly peaked), and FeII and/or
MgII emission lines. The massive YSO distribution in the CMD suggests that the
majority of the objects are of similar spectral type as the Herbig Be stars,
but some of them are young O stars.
  The CO emission must come from a relatively dense (~10^{10} cm^{-3}) and hot
(T~ 2000-5000 K) region, sufficiently shielded from the intense UV radiation
field of the young massive star. The hydrogen emission is produced in an
ionised medium exposed to UV radiation. The best geometrical solution is a
dense and neutral circumstellar disk causing the CO bandhead emission, and an
ionised upper layer where the hydrogen lines are produced. We present arguments
that the circumstellar disk is more likely a remnant of the accretion process
than the result of rapid rotation and mass loss such as in Be/B[e] stars.


title: A Transiting Planet of a Sun-like Star

abstract:
  A planet transits an 11th magnitude, G1V star in the constellation Corona
Borealis. We designate the planet XO-1b, and the star, XO-1, also known as GSC
02041-01657. XO-1 lacks a trigonometric distance; we estimate it to be 200+-20
pc. Of the ten stars currently known to host extrasolar transiting planets, the
star XO-1 is the most similar to the Sun in its physical characteristics: its
radius is 1.0+-0.08 R_Sun, its mass is 1.0+-0.03 M_Sun, V sini < 3 km/s, and
its metallicity [Fe/H] is 0.015+-0.04. The orbital period of the planet XO-1b
is 3.941534+-0.000027 days, one of the longer ones known. The planetary mass is
0.90+-0.07 M_Jupiter, which is marginally larger than that of other transiting
planets with periods between 3 and 4 days. Both the planetary radius and the
inclination are functions of the spectroscopically determined stellar radius.
If the stellar radius is 1.0+-0.08 R_Sun, then the planetary radius is
1.30+-0.11 R_Jupiter and the inclination of the orbit is 87.7+-1.2 degrees. We
have demonstrated a productive international collaboration between professional
and amateur astronomers that was important to distinguishing this planet from
many other similar candidates.


title: Dust Processing in Disks around T Tauri Stars

abstract:
  The 8-14 micron emission spectra of 12 T Tauri stars in the Taurus/Auriga
dark clouds and in the TW Hydrae association obtained with the Infrared
Spectrograph (IRS; The IRS is a collaborative venture between Cornell
University and Ball Aerospace Corporation funded by NASA through the Jet
Propulsion Laboratory and the Ames Research Center.) on board Spitzer are
analyzed. Assuming the 10 micron features originate from silicate grains in the
optically thin surface layers of T Tauri disks, the 8-14 micron dust emissivity
for each object is derived from its Spitzer spectrum. The emissivities are fit
with the opacities of laboratory analogs of cosmic dust. The fits include small
nonspherical grains of amorphous silicates (pyroxene and olivine), crystalline
silicates (forsterite and pyroxene), and quartz, together with large fluffy
amorphous silicate grains. A wide range in the fraction of crystalline silicate
grains as well as large silicate grains among these stars are found. The dust
in the transitional-disk objects CoKu Tau/4, GM Aur, and DM Tau has the
simplest form of silicates, with almost no hint of crystalline components and
modest amounts of large grains. This indicates that the dust grains in these
objects have been modified little from their origin in the interstellar medium.
Other stars show various amounts of crystalline silicates, similar to the wide
dispersion of the degree of crystallinity reported for Herbig Ae/Be stars of
mass <2.5 solar masses. Late spectral type, low-mass stars can have significant
fractions of crystalline silicate grains. Higher quartz mass fractions often
accompany low amorphous olivine-to-amorphous pyroxene ratios. It is also found
that lower contrast of the 10 micron feature accompanies greater crystallinity.


title:
Observations of Lick Standard Stars Using the SCORPIO Multi-Slit Unit at
  the SAO 6-m Telescope

abstract:
  We present Lick line-index measurements of standard stars from the list of
Worthey. The spectra were taken with the multi-slit unit of the SCORPIO
spectrograph at the 6-m Special Astrophysical observatory telescope. We
describe in detail our method of analysis and explain the importance of using
the Lick index system for studying extragalactic globular clusters. Our results
show that the calibration of our instrumental system to the standard Lick
system can be performed with high confidence.


title:
The star-formation histories of elliptical galaxies across the
  fundamental plane

abstract:
  We present the first results from a study designed to test whether, given
high-quality spectrophotometry spanning the mid-UV--optical wavelength regime,
it is possible to distinguish the metal content (Z) and star-formation history
(sfh) of individual elliptical galaxies with sufficient accuracy to establish
whether their formation history is linked to their detailed morphology and
position on the Fundamental Plane. From a detailed analysis of UV-optical
spectrophotometry of the `cuspy' elliptical galaxy NGC 3605 and the giant
elliptical NGC 5018 we find that: 1) optical spectra with l > 3500 A may not
contain sufficient data to robustly uncover all the stellar populations present
in individual galaxies, even in such relatively passive objects as ellipticals,
2) the addition of the UV data approaching l = 2500 A holds the key to
establishing well-constrained sfhs, from which we can infer a formation and
evolution history which is consistent with their photometric properties, 3)
despite the superficial similarity of their spectra, the two galaxies have very
different `recent' sfhs -- the smaller, cuspy elliptical NGC 3605 contains a
high-Z population of age ~= 1 Gyr, and has a position on the fundamental plane
typical of the product of a low-z gas-rich merger (most likely at z ~ 0.08),
while the giant elliptical NGC 5018, with a sub-solar secondary population,
appears to have gained its more recent stars via mass transfer / accretion of
gas from its spiral companion, 4) despite these differences in detailed
history, more than 85% of the stellar mass of both galaxies is associated with
an old (9-12 Gyr) stellar population of near-solar Z. This pilot study provides
strong motivation for the construction and analysis of high-quality UV-optical
spectra for a substantial sample of ellipticals spanning the Fundamental Plane.


title: Measurability of vacuum fluctuations and dark energy

abstract:
  Vacuum fluctuations of the electromagnetic field induce current fluctuations
in resistively shunted Josephson junctions that are measurable in terms of a
physical power spectrum. In this paper we investigate under which conditions
vacuum fluctuations can be gravitationally active, thus contributing to the
dark energy density of the universe. Our central hypothesis is that vacuum
fluctuations are gravitationally active if and only if they are measurable in
terms of a physical power spectrum in a suitable macroscopic or mesoscopic
detector. This hypothesis is consistent with the observed dark energy density
in the universe and offers a resolution of the cosmological constant problem.
Using this hypothesis we show that the observable vacuum energy density rho_vac
in the universe is related to the largest possible critical temperature T_c of
superconductors through rho_vac = sigma (kT_c)^4/(hbar^3 c^3), where sigma is a
small constant of the order 10^-3. This relation can be regarded as an analog
of the Stefan-Boltzmann law for dark energy. Our hypothesis is testable in
Josephson junctions where we predict there should be a cutoff in the measured
spectrum at 1.7 THz if the hypothesis is true.


title:
The UV spectrum of HS1700+6416 I. Predicting the metal line content of
  the far UV spectrum

abstract:
  In preparation of a study of the HeII/HI ratio towards the bright QSO
HS1700+6416, we predict the metal line content of the far-UV spectral range by
modelling 18 metal absorption line systems with redshifts 0.2<z<2.6 identified
in the spectrum of this quasar. For that purpose, we investigate the spectral
energy distribution of the metagalactic ionizing radiation field. Simple
photoionization models based on 8 different shapes of the ionizing background
are tested for each system. The adopted energy distributions comprise the
Haardt & Madau (2001, HM) model of metagalactic UV background as well as
typical spectra of AGN and starburst galaxies. The models are evaluated and the
favoured one is estimated. We find that the majority of the considered systems
is best reproduced with a HM-like ionizing radiation, where the HeII break,
formally located at 4 Ryd, is shifted to lower energies (~3 Ryd), probably due
to the opacity of the higher HeII Lyman series lines. The remaining systems can
be reasonably described with models based on the unmodified HM background or
the spectra of AGN or starburst galaxies. This finding supports the idea that
the UV background is spatially variable due to both IGM opacity variations and
to local sources. In comparison to an unmodified HM background, the resulting
ionizing spectrum leads to carbon abundances lower by ~0.5 dex. Furthermore, if
the ionizing radiation field as determined from metal line systems was typical
for the IGM, the expected HeII/HI ratio would be 150 to 190.


title: Hard X-ray emission from the Galactic ridge

abstract:
  We present results of a study of the Galactic ridge X-ray emission (GRXE) in
hard X-rays performed with the IBIS telescope aboard INTEGRAL. The imaging
capabilities of this coding aperture telescope make it possible to account for
the flux from bright Galactic point sources whereas the wide field of view
permits to collect large flux from the underlying GRXE. Extensive study of the
IBIS/ISGRI detector background allowed us to construct a model that predicts
the detector count rate with $\sim1-2$% accuracy in the energy band 17-60 keV.
The derived longitude and latitude profiles of the ridge emission are in good
agreement with the Galactic distribution of stars obtained from infrared
observations. This, along with the measured hard X-ray spectrum of the Galactic
ridge emission strongly indicates its stellar origin. The derived unit stellar
mass emissivity of the ridge in the energy band 17-60 keV, $(0.9 - 1.2)\times
10^{27}$\lummass (assuming a bulge mass of $1-1.3 \times 10^{10} M_\odot$)
agrees with that of local (in the Solar neigborhood) accreting magnetic white
dwarf binaries - dominant contributors to the GRXE at these energies. In
addition, the shape of the obtained GRXE spectrum can be used to determine the
average mass of white dwarfs in such systems in the Galaxy as $\sim0.5
M_{\sun}$. The total hard X-ray luminosity of the GRXE is $L_{\rm 17-60 keV}
=(3.7\pm0.2)\times10^{37}$\lum in the 17--60 keV band. At energies 70--200 keV
no additional contribution to the total emission of the Galaxy apart from the
detected point sources is seen.


title:
Optimal placement of a limited number of observations for period
  searches

abstract:
  Robotic telescopes present the opportunity for the sparse temporal placement
of observations when period searching. We address the best way to place a
limited number of observations to cover the dynamic range of frequencies
required by an observer. We show that an observation distribution geometrically
spaced in time can minimise aliasing effects arising from sparse sampling,
substantially improving signal detection quality. The base of the geometric
series is however a critical factor in the overall success of this strategy.
Further, we show that for such an optimal distribution observations may be
reordered, as long as the distribution of spacings is preserved, with almost no
loss of quality. This implies that optimal observing strategies can retain
significant flexibility in the face of scheduling constraints, by providing
scope for on-the-fly adaptation. Finally, we present optimal geometric
samplings for a wide range of common observing scenarios, with an emphasis on
practical application by the observer at the telescope. Such a sampling
represents the best practical empirical solution to the undersampling problem
that we are aware of. The technique has applications to robotic telescope and
satellite observing strategies, where target acquisition overheads mean that a
greater total target exposure time (and hence signal-to-noise) can often in
practice be achieved by limiting the number of observations.


title: The VLA Galactic Plane Survey

abstract:
  The VLA Galactic Plane Survey (VGPS) is a survey of HI and 21-cm continuum
emission in the Galactic plane between longitude 18 degrees 67 degr. with
latitude coverage from |b| < 1.3 degr. to |b| < 2.3 degr. The survey area was
observed with the Very Large Array (VLA) in 990 pointings. Short-spacing
information for the HI line emission was obtained by additional observations
with the Green Bank Telescope (GBT). HI spectral line images are presented with
a resolution of 1 arcmin x 1 arcmin x 1.56 km/s (FWHM) and rms noise of 2 K per
0.824 km/s channel. Continuum images made from channels without HI line
emission have 1 arcmin (FWHM) resolution. VGPS images are compared with images
from the Canadian Galactic Plane Survey (CGPS) and the Southern Galactic Plane
Survey (SGPS). In general, the agreement between these surveys is impressive,
considering the differences in instrumentation and image processing techniques
used for each survey. The differences between VGPS and CGPS images are small, <
6 K (rms) in channels where the mean HI brightness temperature in the field
exceeds 80 K. A similar degree of consistency is found between the VGPS and
SGPS. The agreement we find between arcminute resolution surveys of the
Galactic plane is a crucial step towards combining these surveys into a single
uniform dataset which covers 90% of the Galactic disk: the International
Galactic Plane Survey (IGPS). The VGPS data will be made available on the World
Wide Web through the Canadian Astronomy Data Centre (CADC).


title: Probing radio source environments via HI and OH absorption

abstract:
  We present the results of HI and OH absorption measurements towards a sample
of radio sources using the Arecibo 305-m telescope and the GMRT. In total, 27
radio sources were searched for associated 21-cm HI absorption. One totally new
HI absorption system was detected against the radio galaxy 3C258, while five
previously known HI absorption systems, and one galaxy detected in emission,
were studied with improved frequency resolution and/or sensitivity. Our sample
included 17 GPS and CSS objects, 4 of which exhibit HI absorption. This
detection rate of ~25% compares with a value of ~40% by Vermeulen et al. for
similar sources. We detected neither OH emission nor absorption towards any of
the sources that were observed at Arecibo, and estimate a limit on the
abundance ratio of N(HI)/N(OH)>4x10^6 for 3C258. We have combined our results
with those from other available HI searches to compile a heterogeneous sample
of 96 radio sources consisting of 27 GPS, 35 CSS, 13 flat spectrum and 21 large
sources. The HI absorption detection rate is highest (~45%) for the GPS sources
and least for the large sources. We find HI column density to be anticorrelated
with source size, as reported earlier by Pihlstr\"om et al. The HI column
density shows no significant dependence on either redshift or luminosity, which
are themselves strongly correlated. These results suggest that the environments
of radio sources on GPS/CSS scales are similar at different redshifts. Further,
in accordance with the unification scheme, the GPS/CSS galaxies have an HI
detection rate of ~40% which is significantly higher than the detection rate
(~20%) towards the GPS/CSS quasars. Also, the principal (strongest) absorption
component detected towards GPS sources appears blue-shifted in ~65% of the
cases, in agreement with the growing evidence for jet-cloud interactions.


title: Direct X-ray Constraints on Sterile Neutrino Warm Dark Matter

abstract:
  Warm dark matter (WDM) might more easily account for small scale clustering
measurements than the heavier particles typically invoked in Lambda cold dark
matter (LCDM) cosmologies. In this paper, we consider a Lambda WDM cosmology in
which sterile neutrinos nu_s, with a mass m_s of roughly 1-100 keV, are the
dark matter. We use the diffuse X-ray spectrum (total minus resolved point
source emission) of the Andromeda galaxy to constrain the rate of sterile
neutrino radiative decay: nu_s -> nu_{e,mu,tau} + gamma. Our findings demand
that m_s < 3.5 keV (95% C.L.) which is a significant improvement over the
previous (95% C.L.) limits inferred from the X-ray emission of nearby clusters,
m_s < 8.2 keV (Virgo A) and m_s < 6.3 keV (Virgo A + Coma).


title:
On the Age and Metallicity Estimation of Spiral Galaxies Using Optical
  and Near-Infrared Photometry

abstract:
  In integrated-light, some color-color diagrams that use optical and
near-infrared photometry show surprisingly orthogonal grids as age and
metallicity are varied, and they are coming into common usage for estimating
the average age and metallicity of spiral galaxies. In this paper we
reconstruct these composite grids using simple stellar population models from
several different groups convolved with some plausible functional forms of star
formation histories at fixed metallicity. We find that the youngest populations
present (t<2 Gyr) dominate the light, and because of their presence the
age-metallicity degeneracy can be partially broken with broad-band colors,
unlike older populations. The scatter among simple stellar population models by
different authors is, however, large at ages t<2 Gyr. The dominant
uncertainties in stellar population models arise from convective core overshoot
assumptions and the treatment of the thermally pulsing asymptotic giant branch
phase and helium abundance may play a significant role at higher metallicities.
Real spiral galaxies are unlikely to have smooth, exponential star formation
histories, and burstiness will cause a partial reversion to the single-burst
case, which has even larger model-to-model scatter. Finally, it is emphasized
that the current composite stellar population models need some implementation
of chemical enrichment histories for the proper analysis of the observational
data.


title: The Complete BATSE Spectral Catalog of Bright Gamma-Ray Bursts

abstract:
  We present a systematic spectral analysis of 350 bright Gamma-Ray Bursts
(GRBs) observed with the Burst and Transient Source Experiment (BATSE; $\sim$
30 keV -- 2 MeV) with high temporal and spectral resolution. Our sample was
selected from the complete set of 2704 BATSE GRBs based on their energy fluence
or peak photon flux values to assure good statistics, and included 17 short
GRBs. To obtain well-constrained spectral parameters, several photon models
were used to fit each spectrum. We compared spectral parameters resulting from
the fits using different models, and the spectral parameters that best
represent each spectrum were statistically determined, taking into account the
parameterization differences among the models. A thorough analysis was
performed on 350 time-integrated and 8459 time-resolved burst spectra, and the
effects of integration times in determining the spectral parameters were
explored. Using the results, we studied correlations among spectral parameters
and their evolution pattern within each burst. The resulting spectral catalog
is the most comprehensive study of spectral properties of GRB prompt emission
to date, and is available electronically from the High-Energy Astrophysics
Science Archive Research Center (HEASARC). The catalog provides reliable
constraints on particle acceleration and emission mechanisms in GRBs.


title:
Associated 21-cm HI absorption towards the radio galaxy 3C452
  (J2245+3941)

abstract:
  We report the detection of 21-cm HI absorption towards the core of the
Fanaroff-Riley II radio galaxy 3C452 (J2245+3941). The absorption profile is
well resolved into three components; the strongest and narrowest component
being coincident with the velocity corresponding to [O III] emission lines
while the other two components are blue-shifted with respect to it by ~30 and
115 km\s. If the systemic velocity of the host galaxy is determined from
low-ionization lines, which are red-shifted with respect to the [O III] doublet
by about ~200 km\s, then both the [O III] emission and 21-cm absorption lines
are associated with outflowing material. The neutral hydrogen column density is
estimated to be N(HI) = 6.39X10^{20}(T_s/100)(1.0/f_c) cm^{-2}, where T_s and
f_c are the spin temperature and partial coverage of the background source
respectively. If the 21-cm absorber is also responsible for the nuclear
extinction at infrared wavelengths and x-ray absorption, then for a spin
temperature of ~8000 K, the absorber occults only ~10 per cent of the radio
core.


title: Transient pulsed radio emission from a magnetar

abstract:
  Anomalous X-ray pulsars (AXPs) are slowly rotating neutron stars with very
bright and highly variable X-ray emission that are believed to be powered by
ultra-strong magnetic fields of >1e14 G, according to the 'magnetar' model. The
radio pulsations that have been observed from more than 1,700 neutron stars
with weaker magnetic fields have never been detected from any of the dozen
known magnetars. The X-ray pulsar XTE J1810-197 was revealed (in 2003) as the
first AXP with transient emission when its luminosity increased 100-fold from
the quiescent level; a coincident radio source of unknown origin was detected
one year later. Here we show that XTE J1810-197 emits bright, narrow, highly
linearly polarized radio pulses, observed at every rotation, thereby
establishing that magnetars can be radio pulsars. There is no evidence of radio
emission before the 2003 X-ray outburst (unlike ordinary pulsars, which emit
radio pulses all the time), and the flux varies from day to day. The flux at
all radio frequencies is approximately equal -- and at >20 GHz XTE J1810-197 is
currently the brightest neutron star known. These observations link magnetars
to ordinary radio pulsars, rule out alternative accretion models for AXPs, and
provide a new window into the coronae of magnetars.


title:
The Hubble diagram extended to z>>1: the gamma-ray properties of GRBs
  confirm the Lambda-CDM model

abstract:
  Tight constraints on cosmological parameters can be obtained with standard
candles spanning a range of redshifts as large as possible. We propose to treat
SN Ia and long Gamma-Ray Bursts (GRBs) as a single class of candles. Taking
advantage of the recent release of the Supernova Legacy Survey and {\it the
recent finding of a tight correlation among the energetics and other prompt
gamma-ray emission properties of GRBs}, we are able to standardize the
luminosities/energetics of both classes of objects. In this way we can jointly
use GRB and SNIa as cosmological probes to constrain Omega_m and Omega_L and
the Dark Energy equation of state parameters through the same Bayesian method
that we have, so far, applied to GRBs alone. Despite the large disparity in
number (115 SNIa versus 19 GRBs) we show that the constraints on Omega_m and
Omega_L are greatly improved by the inclusion of GRBs. More importantly, the
result of the combined sample is in excellent agreement with the Lambda-CDM
concordance cosmological model and does not require an evolving equation of
state for the Dark Energy.