title: Some Remarks on Extragalactic Globular Clusters

abstract:
  I comment (in a review fashion) on a few selected topics in the field of
extragalactic globular clusters with strong emphasis on recent work. The topics
are: bimodality in the colour distribution of cluster systems, young massive
clusters, and the brightest old clusters. Globular cluster research, perhaps
more than ever, has lead to important (at least to astronomers) progress and
problems in galaxy structure and formation.


title:
Physical Conditoins in Orion's Veil II: A Multi-Component Study of the
  Line of Sight Toward the Trapezium

abstract:
  Orion's Veil is an absorbing screen that lies along the line of sight to the
Orion H II region. It consists of two or more layers of gas that must lie
within a few parsecs of the Trapezium cluster. Our previous work considered the
Veil as a whole and found that the magnetic field dominates the energetics of
the gas in at least one component. Here we use high-resolution STIS UV spectra
that resolve the two velocity components in absorption and determine the
conditions in each. We derive a volume hydrogen density, 21 cm spin
temperature, turbulent velocity, and kinetic temperature, for each. We combine
these estimates with magnetic field measurements to find that magnetic energy
significantly dominates turbulent and thermal energies in one component, while
the other component is close to equipartition between turbulent and magnetic
energies. We observe molecular hydrogen absorption for highly excited v, J
levels that are photoexcited by the stellar continuum, and detect blueshifted S
III and P III. These ions must arise from ionized gas between the mostly
neutral portions of the Veil and the Trapezium and shields the Veil from
ionizing radiation. We find that this layer of ionized gas is also responsible
for He I absorption in the Veil, which resolves a 40-year-old debate on the
origin of He I absorption towards the Trapezium. Finally, we determine that the
ionized and mostly atomic layers of the Veil will collide in less than 85,000
years.


title:
Chandra X-ray Observations of Galaxies in an Off-Center Region of the
  Coma Cluster

abstract:
  We have performed a pilot Chandra survey of an off-center region of the Coma
cluster to explore the X-ray properties and Luminosity Function of normal
galaxies. We present results on 13 Chandra-detected galaxies with optical
photometric matches, including four spectroscopically-confirmed Coma-member
galaxies. All seven spectroscopically confirmed giant Coma galaxies in this
field have detections or limits consistent with low X-ray to optical flux
ratios (fX/fR < 10^-3). We do not have sufficient numbers of X-ray detected
galaxies to directly measure the galaxy X-ray Luminosity Function (XLF).
However, since we have a well-measured optical LF, we take this low X-ray to
optical flux ratio for the 7 spectroscopically confirmed galaxies to translate
the optical LF to an XLF. We find good agreement with Finoguenov et al. (2004),
indicating that the X-ray emission per unit optical flux per galaxy is
suppressed in clusters of galaxies, but extends this work to a specific
off-center environment in the Coma cluster. Finally, we report the discovery of
a region of diffuse X-ray flux which might correspond to a small group
interacting with the Coma Intra-Cluster Medium (ICM).


title:
The Cosmic Ray Precursor of Relativistic Collisionless Shocks: A Missing
  Link in Gamma-Ray Burst Afterglows

abstract:
  Collisionless shocks are commonly argued to be the sites of cosmic ray (CR)
acceleration. We study the influence of CRs on weakly magnetized relativistic
collisionless shocks and apply our results to external shocks in gamma-ray
burst (GRB) afterglows. The common view is that the transverse Weibel
instability (TWI) generates a small-scale magnetic field that facilitates
collisional coupling and thermalization in the shock transition. The TWI field
is expected to decay rapidly, over a finite number of proton plasma skin depths
from the transition. However, the synchrotron emission in GRB afterglows
suggests that a strong and persistent magnetic field is present in the plasma
that crosses the shock; the origin of this field is a key open question. Here
we suggest that the common picture involving TWI demands revision. Namely, the
CRs drive turbulence in the shock upstream on scales much larger than the skin
depth. This turbulence generates a large-scale magnetic field that quenches TWI
and produces a magnetized shock. The new field efficiently confines CRs and
enhances the acceleration efficiency. The CRs modify the shocks in GRB
afterglows at least while they remain relativistic. The origin of the magnetic
field that gives rise to the synchrotron emission is plausibly in the CR-driven
turbulence. We do not expect ultrahigh energy cosmic ray production in external
GRB shocks.


title: X-ray Spectroscopy of Cooling Clusters

abstract:
  We review the X-ray spectra of the cores of clusters of galaxies. Recent high
resolution X-ray spectroscopic observations have demonstrated a severe deficit
of emission at the lowest X-ray temperatures as compared to that expected from
simple radiative cooling models. The same observations have provided compelling
evidence that the gas in the cores is cooling below half the maximum
temperature. We review these results, discuss physical models of cooling
clusters, and describe the X-ray instrumentation and analysis techniques used
to make these observations. We discuss several viable mechanisms designed to
cancel or distort the expected process of X-ray cluster cooling.


title: Integral Field Spectroscopy of the core of Abell 2218

abstract:
  We report on integral field spectrocopy observations, performed with the PPAK
module of the PMAS spectrograph, covering a field-of-view of ~74''X64''
centered on the core of the galaxy cluster Abell 2218. A total of 43 objects
were detected, 27 of them galaxies at the redshift of the cluster. We deblended
and extracted the integrated spectra of each of the objects in the field using
an adapted version of galfit for 3D spectroscopy (galfit3d). We use these
spectra, in combination with morphological parameters derived from deep HST/ACS
images, to study the stellar population and evolution of galaxies in the core
of this cluster.


title: On the 2:1 Orbital Resonance in the HD 82943 Planetary System

abstract:
  We present an analysis of the HD 82943 planetary system based on a radial
velocity data set that combines new measurements obtained with the Keck
telescope and the CORALIE measurements published in graphical form. We examine
simultaneously the goodness of fit and the dynamical properties of the best-fit
double-Keplerian model as a function of the poorly constrained eccentricity and
argument of periapse of the outer planet's orbit. The fit with the minimum
chi_{nu}^2 is dynamically unstable if the orbits are assumed to be coplanar.
However, the minimum is relatively shallow, and there is a wide range of fits
outside the minimum with reasonable chi_{nu}^2. For an assumed coplanar
inclination i = 30 deg. (sin i = 0.5), only good fits with both of the lowest
order, eccentricity-type mean-motion resonance variables at the 2:1
commensurability, theta_1 and theta_2, librating about 0 deg. are stable. For
sin i = 1, there are also some good fits with only theta_1 (involving the inner
planet's periapse longitude) librating that are stable for at least 10^8 years.
The libration semiamplitudes are about 6 deg. for theta_1 and 10 deg. for
theta_2 for the stable good fit with the smallest libration amplitudes of both
theta_1 and theta_2. We do not find any good fits that are non-resonant and
stable. Thus the two planets in the HD 82943 system are almost certainly in 2:1
mean-motion resonance, with at least theta_1 librating, and the observations
may even be consistent with small-amplitude librations of both theta_1 and
theta_2.


title: On the Robustness of Cool Disc Components in Bright ULXs

abstract:
  In this letter, we comment on the robustness of putative cool (kT ~ 0.2 keV)
accretion disc components in the X-ray spectra of the most luminous (L ~ 10^40
erg/s) ultra-luminous X-ray sources (ULXs) in nearby normal galaxies. When
compared to stellar-mass black holes, the low disc temperatures observed in
some ULXs may imply intermediate-mass black hole primaries. Recent work has
claimed that such soft excesses are unlikely to be actual disc components,
based on the lack of variability in these components, and in the overall source
flux. Other work has proposed that alternative phenomenological models, and
complex Comptonisation models, rule-out cool disc components in ULX spectra. An
inspection of the literature on Galactic stellar-mass black holes and black
hole candidates demonstrates that the flux behaviours seen in specific ULXs are
consistent with phenomena observed in well-known Galactic X-ray binaries.
Applying Comptonisation models to simulated disc blackbody plus power-law
spectra shows that at the sensitivity achieved in even the best ULX spectra,
Comptonisation fits are highly model-dependent, and do not yield meaningful
constraints on the accretion flow. In contrast, the need for a soft, thermal
component does not appear to be model-dependent. As we have previously noted,
soft thermal components in ULX spectra may not represent accretion discs, but
present alternatives to this interpretation are not robust.


title: Comments on "Perspectives on Galactic Dynamics via General Relativity"

abstract:
  In this comment we question some arguments presented in astro-ph/0512048 to
refuse the presence of an singular mass surface layer. In particular, incorrect
expressions are used for the disk's surface mass density. We also point out
that the procedure of removing the descontinuity on the $z=0$ plane with a
region of continuous density gradient generates other two regions of
descontinuities with singular mass surface layers making the model unrealistic.


title: Dynamical HII Region Evolution in Turbulent Molecular Clouds

abstract:
  We present numerical radiation-hydrodynamic simulations of the evolution of
HII regions formed in an inhomogeneous medium resulting from turbulence
simulations. We find that the filamentary structure of the underlying density
distribution produces a highly irregular shape for the ionized region, in which
the ionization front escapes to large distances in some directions within
80,000 years. In other directions, on the other hand, neutral gas in the form
of dense globules persists within 1 parsec of the central star for the full
duration of our simulation (400,000 years). Divergent photoablation flows from
these globules maintain a root-mean-squared velocity in the ionized gas that is
close to the ionized sound speed. Simulated images in optical emission lines
show morphologies that are in strikingly detailed agreement with those observed
in real HII regions.


title: X-ray flares: late internal and late external shocks

abstract:
  We analyze several recently detected gamma-ray bursts (GRBs) with late X-ray
flares in the context of late internal shock and late external shock models. We
find that the X-ray flares in GRB 050421 and GRB 050502B originate from late
internal shocks, while the main X-ray flares in GRB 050406 and GRB 050607 may
arise from late external shocks. Under the assumption that the central engine
has two periods of activities, we get four basic types of X-ray light curves.
The classification of these types depends on which period of activities
produces the prompt gamma-ray emission (Type 1 and Type 2: the earlier period;
Type 3 and Type 4: the late period), and on whether the late ejecta catching up
with the early ejecta happens earlier than the deceleration of the early ejecta
(Type 1 and Type 3) or not (Type 2 and Type 4). We find that the X-ray flare
caused by a late external shock is a special case of Type 1. Our analysis
reveals that the X-ray light curves of GRBs 050406, 050421, and 050607 can be
classified as Type 1, while the X-ray light curve of GRB 050502B is classified
as Type 2. However, the X-ray light curve of GRB 050406 is also likely to be
Type 2. We also predict a long-lag short-lived X-ray flare caused by the inner
external shock, which forms when a low baryon-loading long-lag late ejecta
decelerates in the non-relativistic tail of an outer external shock driven by
an early ejecta.


title:
X-ray and optical properties of new Gamma Cas-like objects discovered in
  X-ray surveys

abstract:
  A growing number of early Be stars discovered in X-ray surveys exhibit X-ray
luminosities intermediate between those of normal stars and those of most
Be/X-ray binaries in quiescence. Their X-ray spectra are also much harder than
those of shocked wind OB stars and can be best fitted by a thin thermal plasma
with T ~ 10^8 K, added to a cooler and much fainter thermal component. An iron
line complex including a fluorescence component is detected in many cases.
There is no evidence for coherent pulsations in any of these systems but strong
variability on time scales as short as 100 s is usually observed. Large
oscillations with quasi-periods of the order of one hour or more are detected
in the X-ray light curves of several sources, but have so far failed to prove
to be strictly periodic. The optical and X-ray properties of these new objects
strikingly resemble those of the so far unique and enigmatic Be star Gamma-Cas
and define a new class of X-ray emitters. We discuss the possible origin of the
X-ray emission in the light of the models proposed for Gamma-Cas, magnetic
disc-star interaction or accretion onto a compact companion object -- neutron
star or white dwarf.


title:
PMAS: The Potsdam Multi Aperture Spectrophotometer. II. The Wide
  Integral Field Unit PPak

abstract:
  PPak is a new fiber-based Integral Field Unit (IFU), developed at the
Astrophysical Institute Potsdam, implemented as a module into the existing PMAS
spectrograph. The purpose of PPak is to provide both an extended field-of-view
with a large light collecting power for each spatial element, as well as an
adequate spectral resolution. The PPak system consists of a fiber bundle with
331 object, 36 sky and 15 calibration fibers. The object and sky fibers collect
the light from the focal plane behind a focal reducer lens. The object fibers
of PPak, each 2.7 arcseconds in diameter, provide a contiguous hexagonal
field-of-view of 74 times 64 arcseconds on the sky, with a filling factor of
60%. The operational wavelength range is from 400 to 900nm. The PPak-IFU,
together with the PMAS spectrograph, are intended for the study of extended,
low surface brightness objects, offering an optimization of total
light-collecting power and spectral resolution. This paper describes the
instrument design, the assembly, integration and tests, the commissioning and
operational procedures, and presents the measured performance at the telescope.


title: Low Mass X-ray Binary As the Progenitor of PSR J1713+0747

abstract:
  We have calculated the evolution of low-mass X-ray binaries that leads to the
formation of the binary radio pulsars like PSR J1713+0747. We show that the
mass transfer is most likely to be nonconservative, due to unstable disk
accretion, to account for the mass of PSR J1713+0747, which is close to its
initial value. We assume that part of the lost material from the binary may
form a circumbinary disk, and find that it can significantly influence the mass
transfer processes. We briefly discuss the implications of the circumbinary
disks on the evolution of low-mass X-ray binaries and the formation of low-mass
binary pulsars.


title: Two-phase X-ray burst from GX 3+1 observed by INTEGRAL

abstract:
  INTEGRAL detected on August 31, 2004, an unusual thermonuclear X-ray burst
from the low-mass X-ray binary GX 3+1. Its duration was 30 min, which is
between the normal burst durations for this source (<~10 s) and the superburst
observed in 1998 (several hours). We see emission up to 30 keV energy during
the first few seconds of the burst where the bolometric peak luminosity
approaches the Eddington limit. This peculiar burst is characterized by two
distinct phases: an initial short spike of ~6 s consistent with being similar
to a normal type I X-ray burst, followed by a remarkable extended decay of
cooling emission. We discuss three alternative schemes to explain its twofold
nature: 1) unstable burning of a hydrogen/helium layer involving an unusually
large amount of hydrogen, 2) pure helium ignition at an unusually large depth
(unlikely in the present case), and 3) limited carbon burning at an unusually
shallow depth triggered by unstable helium ignition. Though none of these
provide a satisfactory description of this uncommon event, the former one seems
the most probable.


title: A new analysis of the nucleus of NGC 1068 with MIDI observations

abstract:
  We present a new analysis of the very first mid-infrared N-band long-baseline
interferometric observations of an extragalactic source: the nucleus of the
Seyfert 2 galaxy NGC 1068, obtained with MIDI (Mid-InfrareD Interferometer),
the mid-infrared beamcombiner at the European Southern Observatory (ESO) Very
Large Telescope Interferometer (VLTI). The resolution of 10 mas allows to study
the compact central core of the galaxy between 8 and 13 microns. Both
visibility measurements and MIDI spectrum are well reproduced with a simple
radiative transfer model with two concentric spherical components. The derived
angular sizes and temperatures are about 35 and 83 mas, and 361 K and 226 K for
these two components respectively. Some other evidences strongly support such
low temperatures. This modeling also provides the variation of optical depth as
a function of wavelength for the extended component across the N-band pointing
towards the presence of amorphous silicate grains. This shows that MIDI
actually carried out the first direct observations of the distribution of dust
around the central engine. Together with other observational pieces, we are
able to move a step forward in the reconstruction of the picture drawn for
AGNs.


title:
Photodissociation of organic molecules in star-forming regions II:
  Acetic acid

abstract:
  Fragments from organic molecule dissociation (such as reactive ions and
radicals) can form interstellar complex molecules like amino acids. The goal of
this work is to experimentally study photoionization and photodissociation
processes of acetic acid (CH$_3$COOH), a glycine (NH$_2$CH$_2$COOH) precursor
molecule, by soft X-ray photons. The measurements were taken at the Brazilian
Synchrotron Light Laboratory (LNLS), employing soft X-ray photons from a
toroidal grating monochromator (TGM) beamline (100 - 310 eV). Mass spectra were
obtained using the photoelectron photoion coincidence (PEPICO) method. Kinetic
energy distribution and abundances for each ionic fragment have been obtained
from the analysis of the corresponding peak shapes in the mass spectra.
Absolute photoionization and photodissociation cross sections were also
determined. We have found, among the channels leading to ionization, that only
4-6% of CH$_3$COOH survive the strong ionization field. CH$_3$CO$^+$, COOH$^+$
and CH$_3^+$ ions are the main fragments, and the presence of the former may
indicate that the production-destruction process of acetic acid in hot
molecular cores (HMCs) could decrease the H$_2$O abundance since the net result
of this process converts H$_2$O into OH + H$^+$. The COOH$^+$ ion plays an
important role in ion-molecule reactions to form large biomolecules like
glycine.


title:
Resolving the disk rotation of HD 97048 and HD 100546 in the [O I] 6300A
  line: evidence for a giant planet orbiting HD 100546

abstract:
  Aims. We intend to spatially and spectrally resolve the [O I] emission region
in two nearby Herbig stars.
  Methods. We present high-resolution (R = 80,000) VLT/UVES echelle spectra of
the [O I] 6300A line in the Herbig Ae/Be stars HD 97048 and HD 100546. Apart
from the spectral signature, also the spatial extent of the [O I] emission
region is investigated. For both stars, we have obtained spectra with the slit
positioned at different position angles on the sky.
  Results. The [O I] emission region of HD 100546 appears to be coinciding with
the dust disk, its major axis located at 150+/-11 degrees east of north. The SE
part of the disk moves towards the observer, while the NW side is redshifted.
The [O I] emission region rotates counterclockwise around the central star. For
HD 97048, the position angle of the emission region is 160+/-19 degrees east of
north, which is the first determination of this angle in the literature. The
southern parts of the disk are blueshifted, the northern side moves away from
us. Our data support the idea that a gap is present at 10AU in the disk of HD
100546. Such a gap is likely planet-induced. We estimate the mass and orbital
radius of this hypothetical companion responsible for this gap to be 20 Jupiter
masses and 6.5 AU respectively.
  Conclusions. Based on temporal changes in the [O I] line profile, we conclude
that inhomogeneities are present in the [O I] emission region of HD 100546.
These ``clumps'' could be in resonance with the suggested companion, orbiting
the central star in about 11 yr. If confirmed, these observations could point
to the existence of an object straddling the line between giant planet and
brown dwarf in a system as young as 10 million years.


title: Molecular gas in the Andromeda galaxy

abstract:
  We present a new 12CO(J=1-0)-line survey of the Andromeda galaxy, M31,
covering the bright disk with the highest resolution to date (85 pc along the
major axis), observed On-the-Fly (in italics) with the IRAM 30-m telescope. We
discuss the distribution of the CO emission and compare it with the
distributions of HI and emission from cold dust traced at 175mum. Our main
results are: 1. Most of the CO emission comes from the radial range R=3-16 kpc,
but peaks near R=10 kpc. The emission is con- centrated in narrow, arm-like
filaments defining two spiral arms with pitch angles of 7d-8d. The average
arm-interarm brightness ratio along the western arms reaches 20 compared to 4
for HI. 2. For a constant conversion factor Xco, the molecular fraction of the
neutral gas is enhanced in the arms and decreases radially. The apparent
gas-to-dust ratios N(HI)/I175 and (N(HI)+2N(H2))/I175 increase by a factor of
20 between the centre and R=14 kpc, whereas the ratio 2N(H2)/I175 only
increases by a factor of 4. Implications of these gradients are discussed. In
the range R=8-14 kpc total gas and cold dust are well correlated; molecular gas
is better correlated with cold dust than atomic gas.


title: Air Shower Properties with the Gluon Saturation Model BBL

abstract:
  The hadronic interaction model BBL implements the ideas of gluon saturation
due to large densities. When approaching the black body limit at high energies,
leading partons acquire large transverse momenta which breaks up their
coherence. This leads to a suppression of forward scattering, and is therefore
important for air showers. We discuss some general aspects of this new approach
and their influence on air shower properties as seen by fluorescence and
surface detectors: The position of the shower maximum is reduced due to
stronger absorption in the atmosphere. The lateral distribution functions
become flatter for the same reason. Muons are produced abundantly due to high
multiplicities in the mid-rapidity region. The response of water Cherenkov
detectors and comparisons to other interaction models are shown.


title: Kinematic Control of the Inertiality of ICRS Catalogs

abstract:
  We perform a kinematic analysis of the Hipparcos and TRC proper motions of
stars by using a linear Ogorodnikov-Milne model. All of the distant (r more
than 0.2 kpc) stars of the Hipparcos catalog have been found to rotate around
the Galactic y axis with an angular velocity of -0.36 +/- 0.09 mas/year. One of
the causes of this rotation may be an uncertainty in the lunisolar precession
constant adopted when constructing the ICRS. In this case? the correction to
the IAU (1976) lunisolar precession constant in longitude is shown to be -3.26
+/- 0.10 mas/yr. Based on the TRC catalog, we have determined the main Oort
constants: A = 14.9 +/- 1.0 and B = -10.8 +/- 0.3 km/s/kpc. The component of
the model that describes the rotation of all TRC stars around the Galactic y
axis is nonzero for all magnitudes, My= -0.86 +/- 0.11 mas/yr.


title:
Irradiated atmospheres of accreting magnetic white dwarfs with an
  application to the polar AM Herculis

abstract:
  We present a pilot study of atmospheres of accreting magnetic white dwarfs
irradiated by intense fluxes at ultraviolet to infrared wavelengths. The model
uses a standard LTE stellar atmosphere code which is expanded by introducing an
angle-dependent external radiation source. The present results are obtained for
an external source with the spectral shape of a 10000K blackbody and a freely
adjustable spectral flux. The model provides an explanation for the observed
largely filled-up Lyman lines in the prototype polar AM Herculis during its
high states. It also confirms the hypotheses (i) that irradiation by cyclotron
radiation and other radiation sources is the principle cause for the large
heated polar caps surrounding the accretion spots on white dwarfs in polars and
(ii) that much of the reprocessed light appears in the far ultraviolet and not
in the soft X-ray regime as suggested in the original simple theories. We also
briefly discuss the role played by hard X-rays in heating the polar cap.


title: Kinematic Peculiarities of Gould Belt Stars

abstract:
  We analyzed the space velocities of Gould Belt stars younger than 125 Myr
located at heliocentric distances <650 pc. We determined the rotation and
expansion parameters of the Gould Belt by assuming the existence of a single
kinematic center whose direction was found to be the following:
  $l_\circ=128^\circ$ and $R_\circ=150$ pc. The linear velocities reach their
maximum at a distance of $\approx300$ pc from the center and are -6 km s$^{-1}$
for the rotation (whose direction coincides with the Galactic rotation) and +4
km s$^{-1}$ for the expansion. The stellar rotation model used here is shown to
give a more faithful description of the observed velocity field than the linear
model based on the Oort constants $A_G$ and $B_G$. We present evidence that the
young clusters $\beta$ Pic, Tuc/HorA, and TWA belong to the Gould Belt
structure.


title: Astrometric Control of the Inertiality of the Hipparcos Catalog

abstract:
  Based on the most complete list of the results of an individual comparison of
the proper motions for stars of various programs common to the Hipparcos
catalog, each of which is an independent realization of the inertial reference
frame with regard to stellar proper motions, we redetermined the vector
$\omega$ of residual rotation of the ICRS system relative to the extragalactic
reference frame. The equatorial components of this vector were found to be the
following: $\omega_x = +0.04\pm 0.15$ mas yr$^{-1}$, $\omega_y = +0.18\pm 0.12$
mas yr$^{-1}$, and $\omega_z = -0.35\pm 0.09$ mas yr$^{-1}$.


title: New Developments in Extra-dimensional Dark Matter

abstract:
  We summarize the main features of several dark matter candidates in
extra-dimensional theories. In particular, we review Kaluza-Klein (KK)
gravitons in universal extra dimensions and branons in brane-world models. KK
gravitons are superWIMP (superweakly-interacting massive particle) dark matter,
and branons are WIMP (weakly-interacting massive particle) dark matter. Both
dark matter candidates are naturally produced in the correct amount to form
much or all of dark matter.


title:
A Solution to the Problem of Phaseless Mapping for a High-Orbit
  Space-Ground Radio Interferometer

abstract:
  We consider the problem of mapping with ultra-high angular resolution using a
space-ground radio interferometer with a space antenna in a high orbit,whose
apogee height exceeds the radius of the Earth by a factor of ten. In this case,
a multielement interferometer essentially degenerates into a two-element
interferometer. The degeneracy of the close-phase relations prevents the use of
standard methods for hybrid mapping and self-calibration for the correct
reconstruction of images. We propose a new phaseless mapping method based on
methods for the reconstruction of images in the complete absence of phase
information, using only the amplitudes of the spatial-coherence function of the
source. In connection with this problem, we propose a new method for the
reliable solution of the phase problem, based on optimizing
information-carrying nonlinear functionals, in particular, the Shannon entropy.
Results of simulations of mapping radio sources with various structures with
ultra-high angular resolution in the framework of the RADIOASTRON mission are
presented.


title: An investigation of Fe XV emission lines in solar flare spectra

abstract:
  Previously, large discrepancies have been found between theory and
observation for Fe XV emission line ratios in solar flare spectra covering the
224-327 A wavelength range, obtained by the Naval Research Laboratory's S082A
instrument on board Skylab. These discrepancies have been attributed to either
errors in the adopted atomic data or the presence of additional atomic
processes not included in the modelling, such as fluorescence. However our
analysis of these plus other S082A flare observations (the latter containing Fe
XV transitions between 321-482 A), performed using the most recent Fe XV atomic
physics calculations in conjunction with a CHIANTI synthetic flare spectrum,
indicate that blending of the lines is primarily responsible for the
discrepancies. As a result, most Fe XV lines cannot be employed as electron
density diagnostics for solar flares, at least at the spectral resolution of
S082A and similar instruments (i.e. ~ 0.1 A). An exception is the intensity
ratio I(321.8 A)/I(327.0 A), which appears to provide good estimates of the
electron density at this spectral resolution.


title: Hydrogen and helium traces in type Ib-c supernovae

abstract:
  The spectroscopic properties of a selected optical photospheric spectra of
core collapse supernovae (CCSNe) are investigated.Special attention is devoted
to traces of hydrogen at early phases.
  The generated spectra are found to match the observed ones reasonably well,
including a list of only 23 candidate ions. Guided by SN Ib 1990I, the observed
trough near 6300\AA is attributed to H$\alpha$ in almost all Type Ib events,
although in some objects it becomes too weak to be discernible, especially at
later phases. Alternative line identifications are discussed. Differences in
the way hydrogen manifests its presence within CCSNe are highlighted. In Type
Ib SNe, the H$\alpha$ contrast velocity (i.e. line velocity minus the
photospheric velocity) seems to increase with time at early epochs, reaching
values as high as 8000 km s$^{-1}$ around 15-20 days after maximum and then
remains almost constant. The derived photospheric velocities, indicate a lower
velocity for Type II SNe 1987A and 1999em as compared to SN Ic 1994I and SN IIb
1993J, while Type Ib events display a somewhat larger variation. The scatter,
around day 20, is measured to be $\sim$5000 km s$^{-1}$. Following two simple
approaches, rough estimates of ejecta and hydrogen masses are given. A mass of
hydrogen of approximately 0.02 $M_\odot$ is obtained for SN 1990I, while SNe
1983N and 2000H ejected $\sim$0.008 $M_\odot$ and $\sim$0.08 $M_\odot$ of
hydrogen, respectively. SN 1993J has a higher hydrogen mass, $\sim 0.7$
$M_\odot$ with a large uncertainty. A low mass and thin hydrogen layer with
very high ejection velocities above the helium shell, is thus the most likely
scenario for Type Ib SNe. Some interesting and curious issues relating to
oxygen lines suggest future investigations.


title:
High brightness temperatures and circular polarisation in extra-galactic
  radio sources

abstract:
  Some rapidly variable extra-galactic radio sources show very high brightness
temperatures T_B>10^{12}K and high degrees of circular polarisation (1%).
Standard synchrotron models that assume a power-law electron distribution
cannot produce such high temperatures and have much lower degrees of intrinsic
circular polarisation. We examine the synchrotron and inverse Compton radiation
from a monoenergetic electron distribution using standard synchrotron theory.
Constraints on the source parameters are found by formulating the results as
functions of the source size, Doppler boosting factor, optical depth to
synchrotron self-absorption, maximum frequency of synchrotron emission, and the
strength of the inverse Compton radiation. The model gives brightness
temperatures T_B=10^{13}K to 10^{14}K for moderate (<10) Doppler boosting
factors and intrinsic degrees of circular polarisation at the percent level. It
predicts a spectrum I_\nu\propto\nu^{1/3} between the radio and the infra-red
as well as emission in the MeV to GeV range. We find the conditions under which
electrons do not cool within the source, enabling the GHz emission to emerge
without absorption and the potentially catastrophic energy losses by inverse
Compton scattering to be avoided. We suggest that sources such as PKS 1519
-273, PKS 0405 -385 and J 1819 +3845 can be understood within this scenario
without invoking high Doppler boosting factors, coherent emission mechanisms,
or the dominance of proton synchrotron radiation.


title:
Reflections on Reflexions: II. Effects of Light Echoes on the luminosity
  and spectra of Type Ia Supernovae

abstract:
  In this paper we present and discuss the effects of scattered light echoes
(LE) on the luminosity and spectral appearance of Type Ia Supernovae (SNe).
After introducing the basic concepts of LE spectral synthesis, by means of LE
models and real observations we investigate the deviations from pure SN
spectra, light and colour curves, the signatures that witness the presence of a
LE and the possible inferences on the extinction law. The effects on the
photometric parameters and spectral features are also discussed. In particular,
for the case of circumstellar dust, LEs are found to introduce an apparent
relation between the post-maximum decline rate and the absolute luminosity
which is most likely going to affect the well known Pskowski-Phillips relation.


title: Signatures of Extragalactic Dust in pre-Swift GRB Afterglows

abstract:
  We present the results of a systematic analysis of gamma-ray burst afterglow
spectral energy distributions (SEDs) in the optical/near-infrared bands. Our
input list includes the entire world sample of afterglows observed in the
pre-Swift era by the end of 2004 that have sufficient publicly available data.
We apply various dust extinction models to fit the observed SEDs (Milky Way,
Large Magellanic Cloud and Small Magellanic Cloud) and derive the corresponding
intrinsic extinction in the GRB host galaxies and the intrinsic spectral slopes
of the afterglows. We then use these results to explore the parameter space of
the power-law index of the electron distribution function and to derive the
absolute magnitudes of the unextinguished afterglows.


title:
Constraints on the Physical Parameters of the Dark Energy Using a
  Model-Independent Approach

abstract:
  Understanding the physical nature of the dark energy which appears to drive
the accelerated expansion of the unvierse is one of the key problems in physics
and cosmology today. This important problem is best studied using a variety of
mutually complementary approaches. Daly and Djorgovski (2003, 2004) proposed a
model independent approach to determine a number of important physical
parameters of the dark energy as functions of redshift directly from the data.
Here, we expand this method to include the determinations of its potential and
kinetic energy as functions of redshift. We show that the dark energy potential
and kinetic energy may be written as combinations of the first and second
derivatives of the coordinate distance with respect to redshift. We expand the
data set to include new supernova measurements, and now use a total of 248
coordinate distances that span the redshift range from zero to 1.79. First and
second derivatives of the coordinate distance are obtained as functions of
redshift, and these are combined to determine the potential and kinetic energy
of the dark energy as functions of redshift. An update on the redshift behavior
of the dimensionless expansion rate E(z), the acceleration rate q(z), and the
dark energy pressure p(z), energy density f(z), and equation of state w(z) is
also presented. We find that the standard Omega = 0.3 and Lambda = 0.7 model is
in an excellent agreement with the data. We also show tentative evidence that
the Cardassian and Chaplygin gas models in a spatially flat universe do not fit
the data as well.


title:
The Importance of Off-Jet Relativistic Kinematics in Gamma-Ray Burst Jet
  Models

abstract:
  Gamma-Ray Bursts (GRBs) are widely thought to originate from collimated jets
of material moving at relativistic velocities. Emission from such a jet should
be visible even when viewed from outside the angle of collimation. I summarize
recent work on the special relativistic transformation of the burst quantities
Eiso and Epeak as a function of viewing angle, where Eiso is the
isotropic-equivalent energy of the burst and Epeak is the peak of the burst
spectrum in the power nu F_nu. The formulae resulting from this work serve as
input for a Monte Carlo population synthesis method, with which I investigate
the importance of off-jet relativistic kinematics as an explanation for a class
of GRBs termed "X-ray Flashes" (XRFs). I do this in the context of several
top-hat shaped variable opening-angle jet models. I find that such models
predict a large population of off-jet bursts that are observable and that lie
away from the Epeak ~ Eiso^(1/2) relation. The predicted burst populations are
not seen in current datasets. I investigate the effect of the bulk gamma value
upon the properties of this population of off-jet bursts, as well as the effect
of including an Omega0-Egamma correlation to jointly fit the Epeak ~ Eiso^(1/2)
and Epeak ~ Egamma^(beta) relations, where Omega0 is the opening solid angle of
the GRB jet. I find that the XRFs seen by HETE-2 and BeppoSAX cannot be easily
explained as classical GRBs viewed off-jet. I also find that an inverse
correlation between gamma and Omega0 has the effect of greatly reducing the
visibility of off-jet events. Therefore, unless gamma > 300 for all bursts or
unless there is a strong inverse correlation between gamma and Omega0, top-hat
variable opening-angle jet models produce a significant population of bursts
away from the Epeak ~ Eiso^(1/2) and Epeak ~ Egamma^(beta) relations.


title:
The Optical Gravitational Lensing Experiment. Miras and Semiregular
  Variables in the Large Magellanic Cloud

abstract:
  We use the OGLE-II and OGLE-III data in conjunction with the 2MASS
near-infrared (NIR) photometry to identify and study Miras and Semiregular
Variables (SRVs) in the Large Magellanic Cloud. We found in total 3221
variables of both types, populating two of the series of NIR period-luminosity
(PL) sequences. The majority of these objects are double periodic pulsators,
with periods belonging to both PL ridges. We indicate that in the period -
Wesenheit index plane the oxygen-rich and carbon-rich AGB stars from the NIR PL
sequences C, C' and D split into well separated ridges. Thus, we discover an
effective method of distinguishing between O-rich and C-rich Miras, SRVs and
stars with Long Secondary Periods using their V and I-band photometry. We
present an empirical method of estimating the mean K_s magnitudes of the Long
Period Variables using single-epoch K_s measurements and complete light curves
in the I-band. We utilize these corrected magnitudes to show that the O-rich
and C-rich Miras and SRVs follow somewhat different K_s-band PL relations.


title: Are GRB shocks mediated by the Weibel instability?

abstract:
  It is estimated that the Weibel instability is not generally an effective
mechanism for generating ultrarelativistic astrophysical shocks. Even if the
upstream magnetic field is as low as in the interstellar medium, the shock is
mediated not by the Weibel instability but by the Larmor rotation of protons in
the background magnetic field. Future simulations should be able to verify or
falsify our conclusion.


title: The Convective Urca Process with Implicit Two-Dimensional Hydrodynamics

abstract:
  Consideration of the role of the convective flux in the thermodymics of the
convective Urca neutrino loss process in degenerate, convective, quasi-static,
carbon-burning cores shows that the convective Urca process slows down the
convective current around the Urca-shell, but, unlike the "thermal" Urca
process, does not reduce the entropy or temperature for a given convective
volume. Here we demonstrate these effects with two-dimensional numerical
hydrodynamical calculations. These two-dimensional implicit hydrodynamics
calculations invoke an artificial speeding up of the nuclear and weak rates.
They should thus be regarded as indicative, but still qualitative. We find
that, compared to a case with no Urca-active nuclei, the case with Urca effects
leads to a higher entropy in the convective core because the energy released by
nuclear burning is confined to a smaller volume by the effective boundary at
the Urca shell. All else being equal, this will tend to accelerate the
progression to dynamical runaway. We discuss the open issues regarding the
impact of the convective Urca process on the evolution to the "smoldering
phase" and then to dynamical runaway.


title: Alignment of Outflows with Magnetic Fields in Cloud Cores

abstract:
  We estimate the polarized thermal dust emission from MHD simulations of
protostellar collapse and outflow formation in order to investigate alignment
of outflows with magnetic fields. The polarization maps indicate that alignment
of an outflow with the magnetic field depends on the field strength inside the
cloud core; the direction of the outflow, projected on the plane of the sky, is
aligned preferentially with the mean polarization vector for a cloud core with
a magnetic field strength of 80 microgauss, while it does not tend to be
aligned for 50 microgauss as long as the 1000 AU scale is considered. The
direction of the magnetic field at the cloud center is probed by the direction
of the outflow. In addition, the magnetic field at the cloud center can be
revealed by ALMA even when the source is embedded deeply in the envelope. The
Chandrasekhar-Fermi formula is examined using the polarization maps, indicating
that the field strength predicted by the formula should be corrected by a
factor of 0.24 - 0.44. The correction factor has a tendency to be lower for a
cloud core with a weaker magnetic field.


title:
Effect of Reconnection Probability on Cosmic (Super)string Network
  Density

abstract:
  We perform numerical simulations of cosmic string evolution with
intercommuting probability $P$ in the range $5\times 10^{-3}\le P\le 1$, both
in the matter and radiation eras, using a modified version of the
Allen-Shellard code. We find that the dependence of the scaling density on $P$
is significantly different than the suggested $\rho\propto P^{-1}$ form. In
particular, for probabilities greater than $P\simeq 0.1$, $\rho(1/P)$ is
approximately flat, but for $P$ less than this value it is well-fitted by a
power-law with exponent $0.6^{+0.15}_{-0.12}$. This shows that the enhancement
of string densities due to a small intercommuting probability is much less
prominent than initially anticipated. We interpret the flat part of $\rho(1/P)$
in terms of multiple opportunities for string reconnections during one crossing
time, due to small-scale wiggles. We also propose a two-scale model
incorporating the key physical mechanisms, which satisfactorily fits our
results over the whole range of $P$ covered by the simulations.


title: Ultraviolet-Bright, High-Redshift ULIRGS

abstract:
  We present Spitzer Space Telescope observations of the z=2.38 lya-emitter
over-density associated with galaxy cluster J2143-4423, the largest known
structure (110 Mpc) above z=2. We imaged 22 of the 37 known lya-emitters within
the filament-like structure, using the MIPS 24um band. We detected 6 of the
lya-emitters, including 3 of the 4 clouds of extended (>50 kpc) lyman alpha
emission, also known as Lya Blobs. Conversion from rest-wavelength 7um to total
far-infrared luminosity using locally derived correlations suggests all the
detected sources are in the class of ULIRGs, with some reaching Hyper-LIRG
energies. Lya blobs frequently show evidence for interaction, either in HST
imaging, or the proximity of multiple MIPS sources within the Lya cloud. This
connection suggests that interaction or even mergers may be related to the
production of Lya blobs. A connection to mergers does not in itself help
explain the origin of the Lya blobs, as most of the suggested mechanisms for
creating Lya blobs (starbursts, AGN, cooling flows) could also be associated
with galaxy interactions.


title: The Ups and Downs of the Hubble Constant

abstract:
  A brief history of the determination of the Hubble constant H_0 is given.
Early attempts following Lemaitre (1927) gave much too high values due to
errors of the magnitude scale, Malmquist bias and calibration problems. By 1962
most authors agreed that 75< H_0 <130. After 1975 a dichotomy arose with values
near 100 and others around 55. The former came from apparent-magnitude-limited
samples and were affected by Malmquist bias. New distance indicators were
introduced; they were sometimes claimed to yield high values of H_0, but the
most recent data lead to H_0 in the 60's, yet with remaining difficulties as to
the zero-point of the respective distance indicators. SNe Ia with their large
range and very small luminosity dispersion (avoiding Malmquist bias) offer a
unique opportunity to determine the large-scale value of H_0. Their maximum
luminosity can be well calibrated from 10 SNe Ia in local parent galaxies whose
Cepheids have been observed with HST. An unforeseen difficulty - affecting all
Cepheid distances - is that their P-L relation varies from galaxy to galaxy,
presumably in function of metallicity. A proposed solution is summarized here.
The conclusion is that H_0 = 63.2 +/- 1.3 (random) +/- 5.3 (systematic) on all
scales. The expansion age becomes then (with Omega_m=0.3, Omega_Lambda=0.7)
15.1 Gyr.


title: Birth and Evolution of Isolated Radio Pulsars

abstract:
  We investigate the birth and evolution of Galactic isolated radio pulsars. We
begin by estimating their birth space velocity distribution from proper motion
measurements of Brisken et al. (2002, 2003). We find no evidence for
multimodality of the distribution and favor one in which the absolute
one-dimensional velocity components are exponentially distributed and with a
three-dimensional mean velocity of 380^{+40}_{-60} km s^-1. We then proceed
with a Monte Carlo-based population synthesis, modelling the birth properties
of the pulsars, their time evolution, and their detection in the Parkes and
Swinburne Multibeam surveys. We present a population model that appears
generally consistent with the observations. Our results suggest that pulsars
are born in the spiral arms, with a Galactocentric radial distribution that is
well described by the functional form proposed by Yusifov & Kucuk (2004), in
which the pulsar surface density peaks at radius ~3 kpc. The birth spin period
distribution extends to several hundred milliseconds, with no evidence of
multimodality. Models which assume the radio luminosities of pulsars to be
independent of the spin periods and period derivatives are inadequate, as they
lead to the detection of too many old simulated pulsars in our simulations.
Dithered radio luminosities proportional to the square root of the spin-down
luminosity accommodate the observations well and provide a natural mechanism
for the pulsars to dim uniformly as they approach the death line, avoiding an
observed pile-up on the latter. There is no evidence for significant torque
decay (due to magnetic field decay or otherwise) over the lifetime of the
pulsars as radio sources (~100 Myr). Finally, we estimate the pulsar birthrate
and total number of pulsars in the Galaxy.


title: What Do We Really Know About Cosmic Acceleration?

abstract:
  Essentially all of our knowledge of the acceleration history of the Universe
- including the acceleration itself - is predicated upon the validity of
general relativity. Without recourse to this assumption, we use SNeIa to
analyze the expansion history and find (i) very strong (5 sigma) evidence for a
period of acceleration, (ii) strong evidence that the acceleration has not been
constant, (iii) evidence for an earlier period of deceleration and (iv) only
weak evidence that the Universe has not been decelerating since z~0.3.


title: Local virial relation and velocity anisotropy in self-gravitating system

abstract:
  We investigate the merging process in N-body self-gravitating system from the
viewpoints of the local virial relation which is the relation between the local
kinetic energy and the local potential. We compare both the density profile and
the phase space density profile in cosmological simulations with the critical
solutions of collisionless static state satisfying the local virial (LV)
relation. We got the results that the critical solution can explain the
characteristic density profile with the appropriate value of anisotropy
parameter $\beta \sim 0.5$. It can also explain the power law of the phase
space density profile in the outer part of a bound state. However, it fails in
explaining the central low temperature part which is connected to the scale
invariant phase space density. It can be well fitted to the critical solution
with the higher value of$\beta \sim 0.75$. These results indicate that the LV
relation is not compatible with the scale invariant phase space density in
cosmological simulation.


title: The Molonglo Southern 4 Jy sample (MS4). I. Definition

abstract:
  We have defined a complete sample of 228 southern radio sources at 408 MHz
with integrated flux densities S_408 > 4.0 Jy, Galactic latitude |b| > 10 deg
and declination -85 deg < delta < -30 deg. The main finding survey used was the
Molonglo Reference Catalogue. We describe in detail how the Molonglo Southern 4
Jy sample (MS4) was assembled and its completeness assessed. Sources in the
sample were imaged at 843 MHz with the Molonglo Observatory Synthesis Telescope
to obtain positions accurate to about 1 arcsec, as well as flux densities and
angular sizes; follow-up radio and optical observations are presented in Paper
II. Radio spectra for the MS4 have been compiled from the literature and used
to estimate flux densities at 178 MHz. The strong-source subset of MS4, with
S_178 > 10.9 Jy (SMS4), provides a southern sample closely equivalent to the
well-studied northern 3CRR sample. Comparison of SMS4 with 3CRR shows a
reassuring similarity in source density and median flux density between the two
samples.


title:
A CH3CN and HCO+ survey towards southern methanol masers associated with
  star formation

abstract:
  We present the initial results of a 3-mm spectral line survey towards 83
methanol maser selected massive star-forming regions. Here we report
observations of the J=5-4 and 6-5 rotational transitions of methyl cyanide
(CH3CN) and the J=1-0 transition of HCO+and H13CO+.
  CH3CN emission is detected in 58 sources (70 %) of our sample). We estimate
the temperature and column density for 37 of these using the rotational diagram
method. The temperatures we derive range from 28-166 K, and are lower than
previously reported temperatures, derived from higher J transitions. We find
that CH3CN is brighter and more commonly detected towards ultra-compact HII
(UCHII) regions than towards isolated maser sources. Detection of CH3CN towards
isolated maser sources strongly suggests that these objects are internally
heated and that CH3CN is excited prior to the UCHII phase of massive
star-formation.
  HCO+ is detected towards 82 sources (99 % of our sample), many of which
exhibit asymmetric line profiles compared to H13CO+. Skewed profiles are
indicative of inward or outward motions, however, we find approximately equal
numbers of red and blue-skewed profiles among all classes. Column densities are
derived from an analysis of the HCO+ and H13CO+ line profiles.
  80 sources have mid-infrared counterparts: 68 seen in emission and 12 seen in
absorption as `dark clouds'. Seven of the twelve dark clouds exhibit asymmetric
HCO+ profiles, six of which are skewed to the blue, indicating infalling
motions. CH3CN is also common in dark clouds, where it has a 90 % detection
rate.


title:
The Molonglo Southern 4 Jy sample (MS4). II. ATCA imaging and optical
  identification

abstract:
  Of the 228 sources in the Molonglo Southern 4 Jy Sample (MS4), the 133 with
angular sizes < 35 arcsec have been imaged at 5 GHz at 2-4 arcsec resolution
with the Australia Telescope Compact Array. More than 90% of the sample has
been reliably optically identified, either on the plates of the UK Schmidt
Southern Sky Survey or on R-band CCD images made with the Anglo-Australian
Telescope. A subsample of 137 sources, the SMS4, defined to be a close southern
equivalent of the northern 3CRR sample, was found to have global properties
mostly consistent with the northern sample. Linear sizes of MS4 galaxies and
quasars were found to be consistent with galaxy-quasar unification models of
orientation and evolution.


title:
ROSAT observations of the soft X-ray background and of the cluster soft
  excess emission in the Hercules supercluster

abstract:
  Recent observations with the XMM-Newton satellite confirmed the existence of
the soft excess phenomenon in galaxy clusters, earlier discovered in several
EUVE, ROSAT and BeppoSAX observations. Among the clusters for which XMM has
reported detection of soft excess emission are MKW03s and A2052, two clusters
in the Hercules concentration.
  The Hercules supercluster lies along the southern extension of the North
Polar Spur, a region of bright soft X-ray emission clearly visible in ROSAT
All-Sky Survey images. We analyze 11 pointed ROSAT PSPC observations toward 3
clusters in the Hercule concentration, MKW03s, A2052 and A2063, and 8
neighboring fields in order to investigate the soft X-ray emission in that
region of the sky. We find that the soft X-ray emission varies by a factor of
few on scales of few degrees, rendering the background subtraction a complex
task. If the Noth Polar Spur emission is of local origin, we find that only
A2052 and A2063 have evidence of cluster soft excess emission, and that the
OVII emission lines detected in XMM observations of A2052 and MKW03s are not
associated with the cluster. If part or all of the North Polar Spur soft X-ray
enhancement is of extragalactic nature, the three clusters feature strong soft
excess emission, and the OVII emission lines observed by XMM are genuinely
associated with the clusters.
  We interpret the soft excess emission with the presence of warm gas, either
intermixed with the hot intra-cluster medium or in filamentary structures
located around the clusters, and estimate that the warm gas is approximately as
massive as the hot intra-cluster medium.


title: Galactic dynamo and helicity losses through fountain flow

abstract:
  Nonlinear behaviour of galactic dynamos is studied, allowing for magnetic
helicity removal by the galactic fountain flow. A suitable advection speed is
estimated, and a one-dimensional mean-field dynamo model with dynamic
alpha-effect is explored. It is shown that the galactic fountain flow is
efficient in removing magnetic helicity from galactic discs. This alleviates
the constraint on the galactic mean-field dynamo resulting from magnetic
helicity conservation and thereby allows the mean magnetic field to saturate at
a strength comparable to equipartition with the turbulent kinetic energy.


title:
A High-Accuracy Method for the Removal of Point Sources from Maps of the
  Cosmic Microwave Background

abstract:
  A new method for removing point radio sources and other non-Gaussian noise is
proposed as a means of improving the accuracy of estimates of the angular power
spectrum of the cosmic microwave background (CMB). The main idea of the method
is to reconstruct fluctuations of the CMB in places contaminated by such
emission, while traditional methods simply exclude these regions from
consideration, leading to the appearance of "holes" in the resulting maps. The
fundamental possibility of reconstructing the CMB signal in such holes follows
from the analytical properties of a function with a finite spatial spectrum
(the Silk damping frequency). A two-dimensional median filter is used to
localize the point radio sources. Results of simulations of the method for maps
of modest size are presented. The efficiency of applying the method to
reconstruct the CMB from data with limited resolution and contaminated by
appreciable pixel noise is investigated. The fundamental possibility of
applying the method to reconstruct the CMB distribution in the region of the
Galaxy is also demonstrated.


title: 3D spectroscopy as a tool for investigation of the BLR of lensed QSOs

abstract:
  Selective amplification of the line and continuum source by microlensing in a
lensed quasar can lead to changes of continuum spectral slopes and line shapes
in the spectra of the quasar components. Comparing the spectra of different
components of the lensed quasar and the spectra of an image observed in
different epochs one can infer the presence of millilensing, microlensing and
intrinsic variability. Especially, microlensing can be used for investigation
of the unresolved broad line (BLR) and continuum emitting region structure in
active galactic nuclei (AGN). Therefore the spectroscopic monitoring of
selected lensed quasars with 3D spectroscopy open new possibility for
investigation of the BLR structure in AGN. Here we discuss observational
effects that may be present during the BLR microlensing in the spectra of
lensed QSOs.


title: A Precessing Ring Model for Low-Frequency Quasi-periodic Oscillations

abstract:
  We develop a simple physical model to describe the most common type of
low-frequency quasi-periodic oscillations (QPOs) seen in a number of accreting
black hole systems, as well as the shape of the relativistically broadened iron
emission lines that often appear simultaneously in such sources. The model is
based on an inclined ring of hot gas that orbits the black hole along geodesic
trajectories. For spinning black holes, this ring will precess around the spin
axis of the black hole at the Lense-Thirring (``frame-dragging'') frequency.
Using a relativistic ray-tracing code, we calculate X-ray light curves and
observed energy spectra as a function of the radius and tilt angle of the ring,
the spin magnitude, and the inclination of the black hole. The model predicts
higher-amplitude QPOs for systems with high inclinations, as seen in a growing
number of black hole binary systems. We find that the Rossi X-ray Timing
Explorer observations of low-frequency QPOs in GRS 1915+105 are consistent with
a ring of radius R ~ 10M orbiting a black hole with spin a/M ~0.5 and
inclination angle of i ~ 70 deg. Finally, we describe how future X-ray missions
may be able to use simultaneous timing and spectroscopic observations to
measure the black hole spin and probe the inner-most regions of the accretion
disk.


title:
Molecular dynamics study of photodissociation of water in crystalline
  and amorphous ice

abstract:
  We present results of classical dynamics calculations, performed to study the
photodissociation of water in crystalline and amorphous ice surfaces at a
surface temperature of 10 K. Dissociation in the top six monolayers is
considered. Desorption of H2O has a low probability (less than 0.5% yield per
absorbed photon) for both types of ice. The final outcome strongly depends on
the original position of the photodissociated molecule. For molecules in the
first bilayer of crystalline ice and the corresponding layers in amorphous ice,
desorption of H atoms dominates. In the second bilayer H atom desorption,
trapping of the H and OH fragments in the ice, and recombination of H and OH
are of roughly equal importance. Deeper into the ice H atom desorption becomes
less important and trapping and recombination dominate. The distribution of
distances traveled by H atoms in the ice peaks at 6 - 7 Angstroms with a tail
going to about 60 Angstroms for both types of ice. The mobility of OH radicals
is low within the ice with most probable distances traveled of 2 and 1
Angstroms for crystalline and amorphous ice, respectively. OH is however quite
mobile on top of the surface, where it has been found to travel more than 80
Angstroms. Simulated absorption spectra of crystalline ice, amorphous ice, and
liquid water are found to be in very good agreement with experiments.


title: Bayesian methods of astronomical source extraction

abstract:
  We present two new source extraction methods, based on Bayesian model
selection and using the Bayesian Information Criterion (BIC). The first is a
source detection filter, able to simultaneously detect point sources and
estimate the image background. The second is an advanced photometry technique,
which measures the flux, position (to sub-pixel accuracy), local background and
point spread function. We apply the source detection filter to simulated
Herschel-SPIRE data and show the filter's ability to both detect point sources
and also simultaneously estimate the image background. We use the photometry
method to analyse a simple simulated image containing a source of unknown flux,
position and point spread function; we not only accurately measure these
parameters, but also determine their uncertainties (using Markov-Chain Monte
Carlo sampling). The method also characterises the nature of the source
(distinguishing between a point source and extended source). We demonstrate the
effect of including additional prior knowledge. Prior knowledge of the point
spread function increase the precision of the flux measurement, while prior
knowledge of the background has onlya small impact. In the presence of higher
noise levels, we show that prior positional knowledge (such as might arise from
a strong detection in another waveband) allows us to accurately measure the
source flux even when the source is too faint to be detected directly. These
methods are incorporated in SUSSEXtractor, the source extraction pipeline for
the forthcoming Akari FIS far-infrared all-sky survey. They are also
implemented in a stand-alone, beta-version public tool that can be obtained at
http://astronomy.sussex.ac.uk/$\sim$rss23/sourceMiner\_v0.1.2.0.tar.gz


title: Nucleosynthesis of Fe60 in massive stars

abstract:
  We discuss at some extent the production of Fe60 in massive stars in the
range between 11 and 120 Msun both in the hydrostatic and explosive stages. We
also compare the Fe60/Al26 gamma-ray line flux ratio obtained according to the
present calculations to the detected value reported by INTEGRAL/SPI.


title: Characteristics and Origin of the Quadruple System at Pluto

abstract:
  Our discovery of two new satellites of Pluto, designated S/2005 P 1 and
S/2005 P 2 (henceforth, P1 and P2), combined with the constraints on the
absence of more distant satellites of Pluto, reveal that Pluto and its moons
comprise an unusual, highly compact, quadruple system. The two newly discovered
satellites of Pluto have masses that are very small compared to both Pluto and
Charon, creating a striking planet-satellite system architecture. These facts
naturally raise the question of how this puzzling satellite system came to be.
Here we show that P1 and P2's proximity to Pluto and Charon, along with their
apparent locations in high-order mean-motion resonances, likely result from
their being constructed from Plutonian collisional ejecta. We argue that
variable optical depth dust-ice rings form sporadically in the Pluto system,
and that rich satellite systems may be found, perhaps frequently, around other
large Kuiper Belt objects.


title:
Chandra and XMM-Newton Observations of a Sample of Low-Redshift FRI and
  FRII Radio-Galaxy Nuclei

abstract:
  We present spectral results, from Chandra and XMM-Newton observations, of a
sample of 22 low-redshift (z < 0.1) radio galaxies, and consider whether the
core emission originates from the base of a relativistic jet, an accretion
flow, or contains contributions from both. We find correlations between the
unabsorbed X-ray, radio, and optical fluxes and luminosities of FRI-type
radio-galaxy cores, implying a common origin in the form of a jet. On the other
hand, we find that the X-ray spectra of FRII-type radio-galaxy cores is
dominated by absorbed emission, with $N_{\rm H} > 10^{23}$ atoms cm$^{-2}$,
that is likely to originate in an accretion flow. We discuss several models
which may account for the different nuclear properties of FRI- and FRII-type
cores, and also demonstrate that both heavily obscured, accretion-related, and
unobscured, jet-related components may be present in all radio-galaxy nuclei.
Any absorbed, accretion-related, components in FRI-type galaxies have low
radiative efficiencies.


title: Proper-Motion Measurements of the Cygnus Egg Nebula

abstract:
  We present the results of proper-motion measurements of the dust shell
structure in the Egg Nebula (AFGL 2688, CRL 2688, V1610 Cyg), based on the
archived two-epoch imaging-polarimetry data in the 2 micron band taken with
NICMOS on-board the Hubble Space Telescope. We measured the amount of motions
of local structures in the nebula by determining their relative shifts over an
interval of 5.5 years. The dynamical age of the nebula is found to be roughly
350 years based on the overall motion of the nebula that exhibits a
Hubble-law-esque linear relation between the measured proper motion and the
projected radial distance from the origin of the expansion. By adopting the
de-projected velocity of 45 km/s at the tips of the bipolar lobes, our
proper-motion measurements indicate that the distance to the Egg Nebula is
about 420 pc and that the lobes are inclined at 7.7 degrees with respect to the
plane of the sky. The refined distance estimate yields the luminosity of the
central star of 3.3 x 10^3 L_sun, the total shell mass of 1.2 M_sun, and the
mass loss rate (the upper limit) of 3.6 x 10^(-3) M_sun/yr. Assuming 0.6 M_sun
central post-AGB stellar mass, the initial mass of the Egg is 1.8 M_sun. Upon
analysis, we also discovered that the central star of the Egg Nebula has proper
motion of its own at the rate of (14, -10) mas/yr.


title: Quiescent times in Gamma-Ray-Bursts: hints of a dormant inner engine

abstract:
  We perform a statistical analysis of the temporal structure of long
Gamma-Ray-Bursts (GRBs). First we consider a sample of bursts in which a long
quiescent time is present. Comparing the pre-quiescence with the
post-quiescence emission we show that they display similar temporal structures,
hardness ratios and emitted powers, but, on the average, the post-quiescence
emission is roughly twice as long as the pre-quiescence emission. We then
consider a sample of long and bright GRBs. We show that the duration of each
emission period is compatible with the duration of an active period computed in
various inner engine models. At the contrary, if the inner engine is assumed to
be always active, i.e. also during the quiescent times, in several cases the
total duration of the burst largely exceeds the theoretical durations. Our
analysis therefore does not support the interpretation of long quiescent times
in terms of stochastic modulation of a continuous wind. Instead the quiescent
times can be interpreted as dormancy periods of the inner engine. Before and
after a dormancy period the inner engine produces similar emissions.


title:
$^{187}$Re(\gamm,n) cross section close to and above the neutron
  threshold

abstract:
  The neutron capture cross section of the unstable nucleus $^{186}$Re is
studied by investigating the inverse photodisintegration reaction
$^{187}$Re($\gamma$,n). The special interest of the {\it s}-process branching
point $^{186}$Re is related to the question of possible {\it s}-process
contributions to the abundance of the {\it r}-process chronometer nucleus
^{187}$Re. We use the photoactivation technique to measure photodisintegration
rates. Our experimental results are in good agreement with two different
statistical model calculations. Although the cross sections predicted by both
models for the inverse reaction $^{186}$Re(n,$\gamma$) is too low to remove the
overproduction of $^{186}$Os; the two predicted neutron-capture cross sections
differ by a factor of 2.4; this calls for future theoretical study.


title:
Simulation of a Hybrid Optical/Radio/Acoustic Extension to IceCube for
  EeV Neutrino Detection

abstract:
  Astrophysical neutrinos at $\sim$EeV energies promise to be an interesting
source for astrophysics and particle physics. Detecting the predicted
cosmogenic (``GZK'') neutrinos at 10$^{16}$ - 10$^{20}$ eV would test models of
cosmic ray production at these energies and probe particle physics at $\sim$100
TeV center-of-mass energy. While IceCube could detect $\sim$1 GZK event per
year, it is necessary to detect 10 or more events per year in order to study
temporal, angular, and spectral distributions. The IceCube observatory may be
able to achieve such event rates with an extension including optical, radio,
and acoustic receivers. We present results from simulating such a hybrid
detector.


title:
Structured FRW universe leads to acceleration: a non-perturbative
  approach

abstract:
  We propose a model universe in the matter dominated phase described by a FRW
background with local inhomogeneities, like our local patch, grown out of the
primordial fluctuations. Our sub-horizon local patch consisting of different
structures is approximated as an inhomogeneous cosmic fluid described by a LTB
metric embedded in a background FRW universe, in which the observer could be
located anywhere. Within the exact general relativistic formulation, the
junction conditions for the only possible matching without a thin shell at the
boundary, neglected so far in the literature, constrains the model in such a
way that the luminosity distance-red shift relation mimics a FRW universe with
dark energy. Therefore, the dimming of SNIa is accounted for in such a {\it
structured} FRW universe. We have also calculated the exact general
relativistic backreaction term and shown how it influences the global Hubble
parameter and the effective density of the cosmic fluid By using an exact
formulation of the general relativistic dynamics of structures in a homogeneous
universe, the claim is therefore stressed that the backreaction of cosmological
perturbations leads to an apparent dimming of the cosmological distances.


title:
Monte Carlo simulations of star clusters -- III. A million body star
  cluster

abstract:
  A revision of Stodolkiewicz's Monte Carlo code is used to simulate the
evolution of million body star clusters. The new method treats each superstar
as a single star and follows the evolution and motion of all individual stellar
objects. A survey of the evolution of N-body systems influenced by the tidal
field of a parent galaxy and by stellar evolution is presented. The process of
energy generation is realized by means of appropriately modified versions of
Spitzer's and Mikkola's formulae for the interaction cross section between
binaries and field stars and binaries themselves. The results presented are in
good agreement with theoretical expectations and the results of other methods.
During the evolution, the initial mass function (IMF) changes significantly.
The local mass function (LMF) around the half--mass radius closely resembles
the actual global mass function (GMF). At the late stages of evolution the mass
of the evolved stars inside the core can be as high as 97% of the total mass in
this region. For the whole system, the evolved stars can compose up to 67% of
the total mass. The evolution of cluster anisotropy strongly depends on initial
cluster concentration, IMF and the strength of the tidal field. The results
presented are the first step in the direction of simulating the evolution of
real globular clusters by means of the Monte Carlo method.


title: Bulk Motions of Spiral Galaxies in the z = 0.03 Volume

abstract:
  We analyze the peculiar velocity field for 2400 flat spiral galaxies selected
from an infrared sky survey (2MFGC). The distances to the galaxies have been
determined from the Tully-Fisher relation in the photometric J band with a
dispersion of 0.45 mag. The bulk motion of this sample relative to the cosmic
microwave background (3K) frame has an amplitude of 199+/-37 km/s in the
direction l = 290 +/- 11, b = +1 +/- 9 degree. The amplitude of the dipole
motion tends to decrease with distance in accordance with the expected
convergence of bulk flows in the 3K frame. We believe that external massive
attractors similar to the Shapley cluster concentration are responsible for
\~60% of the local flow velocity in the z = 0.03 volume.


title: The origin and evolution of cluster magnetism

abstract:
  Random motions can occur in the intergalactic gas of galaxy clusters at all
stages of their evolution. Depending on the poorly known value of the Reynolds
number, these motions can or cannot become turbulent, but in any case they can
generate random magnetic fields via dynamo action. We argue that magnetic
fields inferred observationally for the intracluster medium require dynamo
action, and then estimate parameters of random flows and magnetic fields at
various stages of the cluster evolution. Polarization in cluster radio halos
predicted by the model would be detectable with the SKA.


title:
Estimate black hole masses of AGNs using ultraviolet emission line
  properties

abstract:
  Based on the measured sizes of broad line region of the reverberation-mapping
AGN sample, two new empirical relations are introduced to estimate the central
black hole masses of radio-loud high-redshift ($z > 0.5$) AGNs. First, using
the archival $IUE/HST$ spectroscopy data at UV band for the
reverberation-mapping objects, we obtained two new empirical relations between
the BLR size and \Mg/\C emission line luminosity. Secondly, using the newly
determined black hole masses of the reverberation-mapping sample for
calibration, two new relationships for determination of black hole mass with
the full width of half maximum and the luminosity of \Mg/\C line are also
found. We then apply the relations to estimate the black hole masses of AGNs in
Large Bright Quasar Surveyq and a sample of radio-loud quasars. For the objects
with small radio-loudness, the black hole mass estimated using the $R_{\rm BLR}
- L_{\eMg/\eC}$ relation is consistent with that from the $R_{BLR} -
L_{3000\AA/1350 \AA}$ relation. But for radio-loud AGNs, the mass estimated
from the $R_{BLR} - L_{\eMg/\eC}$ relation is systematically lower than that
from the continuum luminosity $L_{3000\AA/1350\AA}$. Because jets could have
significant contributions to the UV/optical continuum luminosity of radio-loud
AGNs, we emphasized again that for radio-loud AGNs, the emission line
luminosity may be a better tracer of the ionizing luminosity than the continuum
luminosity, so that the relations between the BLR size and UV emission line
luminosity should be used to estimate the black hole masses of high redshift
radio-loud AGNs.


title:
Physical and chemical structure of dense cores in regions of high mass
  star formation

abstract:
  We found that in regions of high mass star formation the CS emission
correlates well with the dust continuum emission and is therefore a good tracer
of the total mass while the N$_2$H$^+$ distribution is frequently very
different. This is opposite to their typical behavior in low-mass cores where
freeze-out plays a crucial role in the chemistry. The behavior of other high
density tracers varies from source to source but most of them are closer to CS.
Radial density profiles in massive cores are fitted by power laws with indices
about -1.6, as derived from the dust continuum emission. The radial temperature
dependence on intermediate scales is close to the theoretically expected one
for a centrally heated optically thin cloud. The velocity dispersion either
remains constant or decreases from the core center to the edge. Several cores
including those without known embedded IR sources show signs of infall motions.
They can represent the earliest phases of massive protostars. There are
implicit arguments in favor of small-scale clumpiness in the cores.


title:
Phase-Space Distributions of Chemical Abundances in Milky Way-type
  Galaxy Halos

abstract:
  [Abridged] Motivated by upcoming data from astrometric and spectroscopic
surveys of the Galaxy, we explore the chemical abundance properties and
phase-space distributions in hierarchically-formed stellar halo simulations set
in a LambdaCDM Universe. Our sample of Milky-Way type stellar halo simulations
result in average metallicities that range from [Fe/H] = -1.3 to -0.9, with the
most metal poor halos resulting from accretion histories that lack destructive
mergers with massive (metal rich) satellites. Our stellar halo metallicities
increase with stellar halo mass. The slope of the [Fe/H]-stellar mass trend
mimics that of the satellite galaxies that were destroyed to build the halos,
implying that the relation propagates hierarchically. All simulated halos
contain a significant fraction of old stellar populations accreted more than 10
Gyr ago and in a few cases, some intermediate age populations exist. In
contrast with the Milky Way, many of our simulated stellar halos contain old
stellar populations which are metal rich, originating in the early accretion of
massive satellites. We suggest that the (metal rich) stellar halo of M31 falls
into this category, while the more metal poor halo of the Milky Way is lacking
in early massive accretion events. Interestingly, our hierarchically-formed
stellar halos often have non-negligible metallicity gradients in both [Fe/H]
and [alpha/Fe]. These gradients extend a few tens of kpc, and can be as large
as 0.5 dex in [Fe/H] and 0.2 dex in [alpha/Fe]. Finally, we find that chemical
abundances can act as a rough substitute for time of accretion of satellite
galaxies. We propose a criterion for identifying tidal streams spatially by
selecting stars with [alpha/Fe] ratios below solar.


title: Flat Cosmology with Coupled Matter and Dark Energies

abstract:
  Three models of a flat universe of coupled matter and dark energies with
different low-redshift parameterizations of the dark energy equation of state
are considered. The dark energy is assumed to vary with time like the trace of
the energy-momentum tensor of cosmic matter. In the radiation-dominated era the
models reduce to standard cosmology. In the matter-dominated era they are, for
modern values of the cosmological parameters, consistent with data from SNe Ia
searches and with the data of Gurvits et al.(1999)for angular sizes of ultra
compact radio sources. We find that the angular size-redshift tests for our
models offer a higher statistical confidence than that based on SNe Ia data. A
comparison of our results with a recent revised analysis of angular
size-redshift legacy data is made,and the implications of our models with
optimized relativistic beaming in the radio sources is discussed. In particular
we find that relativistic beaming implies a Lorentz factor less than 6,in
agreement with its values for powerful Active Galactic Nuclei.


title:
A Deep Radio Survey of Abell 2125 III: The Cluster Core - Merging and
  Stripping

abstract:
  We use radio, near-IR, optical, and X-ray observations to examine dynamic
processes in the central region of Abell 2125. In addition to the central
triple, including members of both major dynamical subsystems identified from a
redshift survey, this region features a galaxy showing strong evidence for
ongoing gas stripping during a high-velocity passage through the gas in the
cluster core. The disk galaxy C153 exhibits a plume stretching toward the
cluster center seen in soft X-rays by Chandra, parts of which are also seen in
[O II] emission and near-UV continuum light. HST imaging shows a distorted
disk, with star-forming knots asymmetrically distributed and remnant spiral
structure possibly defined by dust lanes. The stars and ionized gas in its disk
are kinematically decoupled, demonstrating that pressure stripping must be
important, and that tidal disruption is not the only mechanism at work.
Comparison of the gas properties seen in the X-ray and optical data on the
plume highlight significant features of the history of stripped gas in the
intracluster medium. The nucleus of C153 also hosts an AGN, shown by the weak
and distorted extended radio emission and a radio compact core. The unusual
strength of the stripping signatures in this instance is likely related to the
high relative velocity of the galaxy with respect to the intracluster medium,
during a cluster/cluster merger, and its passage very near the core of the
cluster. Another sign of recent dynamical events is diffuse starlight
asymmetrically placed about the central triple in a cD envelope. Transient and
extreme dynamical events as seen in Abell 2125 may be important drivers of
galaxy evolution in the cores of rich clusters.


title:
The Possibility of Curved Spacetime, Black Holes, and Big Bang is Less
  than One Billionth

abstract:
  Gravity whose nature is fundamental to the understanding of solar system,
galaxies and the structure and evolution of the Universe, is theorized by the
assumption of curved spacetime, according to Einstein`s general theory of
relativity (EGR). Particles move on curved spacetime along straight lines
(geodesics). In the last year, I proposed the mirrored version of EGR, the
flat-spacetime general relativity (FGR), in which particles move along curved
lines on flat spacetime. This puts gravitational study back to the traditional
Lagrangian formulation. In fact, all claimed accurate verification of general
relativity is the verification of FGR, because people when confronting GR to
observational data, calculate time, distance, or angle by directly using the
coordinates in Schwarzschild solution or in post Newtonian formulation. For
example, people calculate the angles by directly using the coordinate $\phi$.
However, only when spacetime is flat does there exists one coordinate system
which has direct meaning of time, distance, angle, and vice verse. This is the
famous Riemann theorem. Therefore, the more claims are made that classical
tests of general relativity fit data with great accuracy, the more falsified is
the curved-spacetime assumption. People made three such specious claims to EGR
as collected in the present paper. However, FGR predicts observationally
verified results consistently for solar system, galaxies, and the universe on
the whole. I show that the possibility of curved spacetime, black holes, and
big bang is less than one billionth. An experiment is proposed whose results
will completely decide the fate of curved spacetime assumption. with the
original article `Einstein`s Geometrization vs. Holonomic Cancellation of
Gravity via Spatial Coordinate-rescale` attached.


title:
The Giant X-ray Flare of GRB 050502B: Evidence for Late-Time Internal
  Engine Activity

abstract:
  Until recently, X-ray flares during the afterglow of gamma ray bursts (GRBs)
were a rarely detected phenomenon, thus their nature is unclear. During the
afterglow of GRB 050502B, the largest X-ray flare ever recorded rose rapidly
above the afterglow lightcurve detected by the Swift X-ray Telescope. The peak
flux of the flare was >500 times that of the underlying afterglow, and it
occurred at >12 minutes after the nominal prompt burst emission. The fluence of
this X-ray flare, (1.0 +/- 0.05) x 10^{-6} erg cm^{-2} in the 0.2-10.0 keV
energy band, exceeded the fluence of the nominal prompt burst. The spectra
during the flare were significantly harder than those measured before and after
the flare. Later in time, there were additional flux increases detected above
the underlying afterglow, as well as a break in the afterglow lightcurve. All
evidence presented below, including spectral and particularly timing
information during and around the giant flare, suggests that this giant flare
was the result of internal dissipation of energy due to late central engine
activity, rather than an afterglow-related effect. We also find that the data
are consistent with a second central engine activity episode, in which the
ejecta is moving slower than that of the initial episode, causing the giant
flare and then proceeding to overtake and refresh the afterglow shock, thus
causing additional activity at even later times in the lightcurve.


title: CCS and NH3 emission associated with low-mass young stellar objects

abstract:
  In this work we present a sensitive and systematic single-dish survey of CCS
emission (complemented with ammonia observations) at 1 cm, toward a sample of
low- and intermediate-mass young star forming regions known to harbor water
maser emission, made with NASA's 70 m antenna at Robledo de Chavela, Spain.
  Out of the 40 star forming regions surveyed in the CCS(2_{1}-1_{0}) line,
only 6 low-mass sources show CCS emission: one transitional object between
pre-stellar and protostellar Class 0 phase (GF9-2), three Class 0 protostars
(L1448-IRS3, L1448C, and B1-IRS), a Class I source (L1251A), and a young T
Tauri star (NGC2071-North). Since CCS is considered an ``early-time'' (<10E+5
yr) molecule, we explain these results by either proposing a revision of the
classification of the age of NGC2071-North and L1251A, or suggesting the
possibility that the particular physical conditions and processes of each
source affect the destruction/production of the CCS. No statistically
significant relationship was found between the presence of CCS and parameters
of the molecular outflows and their driving sources. Nevertheless, we found a
significant relationship between the detectability of CCS and the ammonia peak
intensity (higher in regions with CCS), but not with its integrated intensity.
This tendency found may suggest that the narrower ammonia line widths in the
less turbulent medium associated with younger cores may compensate for the
differences in ammonia peak intensity, rendering differences in integrated
intensity negligible. From the CCS detection rate we derive a lifetime of this
molecule of ~(0.7-3) x 10E+4 yr in low-mass star forming regions.


title: 3D Spectroscopy of Herbig-Haro objects

abstract:
  HH 110 and HH 262 are two Herbig-Haro jets with rather peculiar, chaotic
morphology. In the two cases, no source suitable to power the jet has been
detected along the outflow, at optical or radio wavelengths. Both, previous
data and theoretical models, suggest that these objects are tracing an early
stage of an HH jet/dense cloud interaction. We present the first results of the
integral field spectroscopy observations made with the PMAS spectrophotometer
(with the PPAK configuration) of these two turbulent jets. New data of the
kinematics in several characteristic HH emission lines are shown. In addition,
line-ratio maps have been made, suitable to explore the spatial excitation an
density conditions of the jets as a function of their kinematics.


title: Mid-infrared properties of X-ray sources in the Extended Groth Strip

abstract:
  Mid-infrared observations of Active Galactic Nuclei (AGN) are important for
understanding of the physical conditions around the central accretion engines.
Chandra and XMM-Newton X-ray observations of a 300 arcmin^2 region in the
Extended Groth Strip are used to select a sample of~150 AGN. The Spitzer
instruments IRAC and MIPS detect 68-80% of these sources, which show a wide
range of mid-infrared properties. About 40% of the sources have red power-law
spectral energy distributions (f_nu ~ nu^alpha, alpha<0) in the 3.6-8 um IRAC
bands. In these sources the central engine dominates the emission at both X-ray
and IR wavelengths. Another 40% of the sources have blue mid-IR spectral energy
distributions (alpha>0) with their infrared emission dominated by the host
galaxy; the remaining 20% are not well-fit by a power law. Published IRAC color
criteria for AGN select most of the red sources, but only some of the blue
sources. As with all other known methods, selecting AGN with mid-IR colors will
not produce a sample that is simultaneously complete and reliable. The IRAC SED
type does not directly correspond to X-ray spectral type (hard/soft). The
mid-IR properties of X-ray-detected Lyman-break, radio, submillimeter, and
optically-faint sources vary widely and, for the most part, are not distinct
from those of the general X-ray/infrared source population. X-ray sources emit
6-11% of the integrated mid--IR light, making them significant contributors to
the cosmic infrared background.


title:
Observations of H-alpha, iron, and oxygen lines in B, Be, and shell
  stars

abstract:
  We have carried out a spectroscopic survey of several B, Be, and shell stars
in optical and near-infrared regions. Line profiles of the H-alpha line and of
selected Fe II and O I lines are presented.


title: Assisted stellar suicide in V617 Sgr

abstract:
  V617 Sgr is a V Sagittae star - a group of binaries thought to be the
galactic counterparts of the Compact Binary Supersoft X-ray Sources - CBSS. To
check this hypothesis, we measured the time derivative of its orbital period.
Observed timings of eclipse minima spanning over 30,000 orbital cycles are
presented. We found that the orbital period evolves quite rapidly: P/Pdot = 1.1
x 10^{6} years. This is consistent with the idea that V617 Sgr is a wind driven
accretion supersoft source. As the binary system evolves with a time-scale of
about one million years, which is extremely short for a low mass evolved
binary, it is likely that the system will soon end either by having its
secondary completely evaporated or by the primary exploding as a supernova of
type Ia.


title:
Astrometric Monitoring of Stellar Orbits at the Galactic Center with a
  Next Generation Large Telescope

abstract:
  We show that with a Next Generation Large Telescope one can detect the
accelerated motions of ~100 stars orbiting the massive black hole at the
Galactic center. The positions and velocities of these stars will be measured
to astrometric and spectroscopic precision several times better than currently
attainable enabling detailed measurements of the gravitational potential in the
neighborhood of the massive black hole. We show that the monitoring of stellar
motions with such a telescopes enables: (1) a measurement of the Galactic
center distance R_0 to better than 0.1% accuracy, (2) a measurement of the
extended matter distribution near the black hole, including that of the exotic
dark matter, (3) a detection of general relativistic effects due to the black
hole including the prograde precession of stars and possibly the black hole
spin, and (4) a detection of gravitational encounters between monitored stars
and stellar remnants that accumulate near the Galactic center. Such encounters
probe the mass function of the remnants.


title: "Expansion" around the vacuum: how far can we go from Lambda?

abstract:
  The cosmological constant ($\Lambda$), i.e., the energy density stored in the
true vacuum state of all existing fields in the Universe, is the simplest and
the most natural possibility to describe the current cosmic acceleration.
However, despite its observational successes, such a possibility exacerbates
the well known $\Lambda$ problem, requiring a natural explanation for its
small, but nonzero, value. In this paper we discuss how different our Universe
may be from the $\Lambda$CDM model by studying observational aspects of a kind
of "expansion" around the vacuum given by the equation of (EOS)
$p_{d}=-\rho_{d} - A \rho_{d}^{\alpha}$. In different parameter regimes such a
parametrization is capable of describing both quintessence-like and
phantom-like dark energy, transient acceleration, and various (non)singular
possibilities for the final destiny of the Universe, including singularities at
finite values of the scale factor, the so-called "Big Rip", as well as sudden
future singularities. By using some of the most recent cosmological
observations we show that if the functional form of the dark energy EOS has
additional parameters very little can be said about their values from the
current observational results, which postpones, until the arrival of more
precise observational data, a definitive answer to the question posed above.


title:
A MMT/Hectospec Redshift Survey of 24 Micron Sources in the Spitzer
  First Look Survey

abstract:
  We present a spectroscopic survey using the MMT/Hectospec fiber spectrograph
of 24 micron sources selected with the Spitzer Space Telescope in the Spitzer
First Look Survey. We report 1296 new redshifts for 24 micron sources,
including 599 with f(24micron) > 1 mJy. Combined with 291 additional redshifts
for sources from the Sloan Digital Sky Survey (SDSS), our observing program was
highly efficient and is ~90% complete for i' < 21 mag and f(24micron) > 1 mJy,
and is 35% complete for i' < 20.5 mag and 0.3 mJy < f(24micron) < 1 mJy. Our
Hectospec survey includes 1078 and 168 objects spectroscopically classified as
galaxies and QSOs, respectively. Combining the Hectospec and SDSS samples, we
find 24 micron-selected galaxies to z < 0.98 and QSOs to z < 3.6, with mean
redshifts of <z(gal)> = 0.27 and <z(QSO)> =1.1. As part of this publication, we
include the redshift catalogs and the reduced spectra; these are also available
online (http://mips.as.arizona.edu/~papovich/fls) and through the NASA/IPAC
Infrared Science Archive (http://irsa.ipac.caltech.edu).


title: X-ray flare modeling in the single giant HR 9024

abstract:
  We analyze a Chandra-HETGS observation of the single G-type giant HR 9024.
The high flux allows us to examine spectral line and continuum diagnostics at
high temporal resolution, to derive plasma parameters (thermal distribution,
abundances, temperature, ...). A time-dependent 1D hydrodynamic loop model with
semi-length 10$^{12}$cm ($\sim R_{\star}$), and impulsive footpoint heating
triggering the flare, satisfactorily reproduces the observed evolution of
temperature and emission measure, derived from the analysis of the strong
continuum emission. The observed characteristics of the flare appear to be
common features in very large flares in active stars (also pre-main sequence
stars), possibly indicating some fundamental physics for these very dynamic and
extreme phenomena in stellar coronae.


title: Flares of Sagittarius a* at Millimeter Wavelengths

abstract:
  We have performed monitoring observations of the flux density toward the
Galactic center compact radio source, Sagittarius A* (Sgr A*), which is a
supermassive black hole, from 1996 to 2005 using the Nobeyama Millimeter Array
of the Nobeyama Radio Observatory, Japan. These monitoring observations of Sgr
A* were carried out in the 3- and 2-mm (100 and 140 GHz) bands, and we have
detected several flares of Sgr A*. We found intraday variation of Sgr A* in the
2000 March flare. The twofold increase timescale is estimated to be about 1.5
hr at 140 GHz. This intraday variability suggests that the physical size of the
flare-emitting region is compact on a scale at or below about 12 AU (~150 Rs;
Schwarzschild radius). On the other hand, clear evidence of long-term periodic
variability was not found from a periodicity analysis of our current millimeter
data set.


title: The early reionization with the primordial magnetic fields

abstract:
  The early reionization of the intergalactic medium, which is favored from the
WMAP temperature-polarization cross-correlations, contests the validity of the
standard scenario of structure formation in the cold dark matter cosmogony. It
is difficult to achieve early enough star formation without rather extreme
assumptions such as very high escape fraction of ionizing photons from
proto-galaxies or a top-heavy initial mass function. Here we propose an
alternative scenario that is additional fluctuations on small scales induced by
primordial magnetic fields trigger the early structure formation. We found that
ionizing photons from Population III stars formed in dark haloes can easily
reionize the universe by $z \simeq 15$ if the strength of primordial magnetic
fields is larger than $0.6 \times 10^{-9}$Gauss.


title:
INTEGRAL detection of hard X-rays from NGC 6334: Nonthermal emission
  from colliding winds or an AGN?

abstract:
  We report the detection of hard X-ray emission from the field of the
star-forming region NGC 6334 with the the International Gamma-Ray Astrophysics
Laboratory INTEGRAL. The JEM-X monitor and ISGRI imager aboard INTEGRAL and
Chandra ACIS imager were used to construct 3-80 keV images and spectra of NGC
6334. The 3-10 keV and 10-35 keV images made with JEM-X show a complex
structure of extended emission from NGC 6334. The ISGRI source detected in the
energy ranges 20-40 keV and 40-80 keV coincides with the NGC 6334 ridge. The
20-60 keV flux from the source is (1.8+-0.37)*10(-11) erg cm(-2) s(-1).
Spectral analysis of the source revealed a hard power-law component with a
photon index about 1. The observed X-ray fluxes are in agreement with
extrapolations of X-ray imaging observations of NGC 6334 by Chandra ACIS and
ASCA GIS. The X-ray data are consistent with two very different physical
models. A probable scenario is emission from a heavily absorbed, compact and
hard Chandra source that is associated with the AGN candidate radio source NGC
6334B. Another possible model is the extended Chandra source of nonthermal
emission from NGC 6334 that can also account for the hard X-ray emission
observed by INTEGRAL. The origin of the emission in this scenario is due to
electron acceleration in energetic outflows from massive early type stars. The
possibility of emission from a young supernova remnant, as suggested by earlier
infrared observations of NGC 6334, is constrained by the non-detection of 44Ti
lines.