title: Performance of the Pierre Auger Observatory Surface Array

abstract:
  The surface detector of the Pierre Auger Observatory is a 1600 water
Cherenkov tank array on a triangular 1.5 km grid. The signals from each tank
are read out using three 9'' photomultipliers and processed at a sampling
frequency of 40 MHz, from which a local digital trigger efficiently selects
shower candidates. GPS signals are used for time synchronization and a wireless
communication system connects all tanks to the central data acquisition system.
Power is provided by a stand-alone solar panel system. With large ambient
temperature variations, that can reach over 20 degrees in 24 hours, high
salinity, dusty air, high humidity inside the tank, and remoteness of access,
the performance and reliability of the array is a challenge. Several key
parameters are constantly monitored to ensure consistent operation. The Surface
Array has currently over 750 detectors and has been in reliable operation since
January 2004. Good uniformity in the response of different detectors and good
long term stability is observed.


title:
From Ultracompact to Extended HII Regions. II: Cloud Gravity and Stellar
  Motion

abstract:
  The dynamical evolution of HII regions with and without stellar motion in
dense, structured molecular clouds is studied. Clouds are modeled in
hydrostatic equilibrium, with gaussian central cores and external halos that
obey r**-2 and r**-3 density power laws. The cloud gravity is included as a
time-independent, external force. Stellar velocities of 0, 2, 8, and 12 km/s
are considered. When stellar motion is included, stars move from the central
core to the edge of the cloud, producing transitions from ultracompact to
extended HII regions as the stars move into lower density regions. The opposite
behavior occurs when stars move toward the cloud cores. The main conclusion of
our study is that ultracompact HII regions are pressure-confined entities while
they remain embedded within dense cores. The confinement comes from ram and/or
ambient pressures. The survival of ultracompact regions depends on the position
of the star with respect to the core, the stellar life-time, and the core
crossing time. Stars with velocities less than the cloud dispersion velocity
can produce cometary shapes smaller than 0.1 pc at times of 20,000 yr or more.
The sequence Ultracompact to Compact to Extended HII region shows a variety of
unpredictable structures due to ionization-shock front instability. Some
ultracompact HII regions with a core-halo morphology might be explained by
self-blocking effects, when stars overtake and ionize leading, piled-up clumps
of neutral gas. We use thermal energy to support the cloud against gravity; the
results remain the same if other types of isotropic cloud support are used.


title:
Observation of the Anisotropy of 10 TeV Primary Cosmic Ray Nuclei Flux
  with the Super-Kamiokande-I Detector

abstract:
  The relative sidereal variation in the arrival direction of primary cosmic
ray nuclei of median energy 10 TeV was measured using downward, through-going
muons detected with the Super-Kamiokande-I detector. The projection of the
anisotropy map onto the right ascension axis has a first harmonic amplitude of
$(6.64 \pm 0.98 {stat.} \pm 0.55 {syst.}) \times 10^{-4}$ and a phase at
maximum at $(33.2^\circ \pm 8.2^\circ {stat.} \pm 5.1^\circ {syst.})$ right
ascension. A sky map in equatorial coordinates indicates an excess region in
the constellation of Taurus and a deficit region toward Virgo. The excess
region is centered at $(\alpha_T, \delta_T) = (75^\circ \pm 7^\circ, -5^\circ
\pm 9^\circ)$ with a half opening angle $\chi_T = (39 \pm 7)^\circ$; the excess
flux is ($0.104 \pm 0.020$)% above the isotropic expectation. The corresponding
parameters for the deficit region are $(\alpha_V, \delta_V) = (205^\circ \pm
7^\circ, 5^\circ \pm 10^\circ)$, $\chi_V = (54 \pm 7)^\circ$, and $(-0.094 \pm
0.014)$%. The data do not allow us to rule out a pure dipole form for the
anisotropy (allowed at 13% confidence level); they are better described by the
excess and deficit cones described above. We explored the implications under
the assumption that the true anisotropy is not distorted too much by the
analysis filter so that it is well-described by the observed excess and deficit
cones.


title:
ISO observations of the interacting galaxy Markarian 297: with the
  powerful supernova remnant 1982aa

abstract:
  Markarian (Mkn) 297 is a complex system with two interacting galaxies.
Observations were made with ISO using ISOCAM, ISOPHOT and LWS. We present
ISOCAM maps at 6.7, 7.7, 12 and 14.3 microns which, with PHT-S spectrometry of
the central interacting region, probe the dust obscured star formation and dust
properties. ISOCAM reveals that the strongest emission region in the four MIR
bands is completely unremarkable at visible and near-IR (e.g. 2MASS)
wavelengths, and does not coincide with the nuclear region of either colliding
galaxy. It shares this striking characteristic with the overlap region of the
colliding galaxies in the Antennae (NGC 4038, 4039), the intragroup region of
Stephan's Quintet, and IC 694 in the interacting system Arp 299. At 15 microns,
the hidden source in Mkn 297 is, respectively, 14.6 and 3.8 times more luminous
than the hidden sources in the Antennae (NGC 4038/4039) and Stephan's Quintet.
Numerical simulations indicate that we see the Mkn 297 interaction about 1.5 x
10e8 years after the collision. ISOCAM shows knots and ridges of emission. The
14.3/7.7 micron ratio map implies widespread strong star formation. Strong
emission features were detected in the ISOPHOT spectrum, while [OI], [OIII] and
[CII] emission lines were seen with LWS. Using data from the three instruments,
luminosities and masses for two dust components were determined. The total
infrared luminosity is approximately 10e11 L_sol, marginally a LIRG. A 1979
supernova generated one of the most powerful known radio remnants (SN 1982aa)
close to the strongest MIR source and identified with star forming region 14 in
the optical. This exceptional supernova explosion may have been accompanied by
a GRB, and a search for a GRB in this direction in contemporaneous satellite
data is recommended.


title:
A Method for Deriving Accurate Gas-Phase Abundances for the Multiphase
  Interstellar Galactic Halo

abstract:
  We describe a new method for determining total gas-phase abundances for the
Galactic ISM with minimal ionization uncertainties. For sight lines toward
globular clusters containing both UV-bright stars and radio pulsars, one can
measure column densities of HI and several metal ions using UV absorption
measurements and of H II using radio dispersion measurements, thereby
minimizing ionization uncertainties. We apply this method to the globular
cluster Messier 3 sight line using FUSE and HST ultraviolet spectroscopy of the
post-asymptotic giant branch star von Zeipel 1128 and radio observations by
Ransom et al. of millisecond pulsars. Ionized hydrogen is 45+/-5% of the total
along this sight line, the highest measured fraction along a high-latitude
pulsar sight line. We derive total gas-phase abundances log N(S)/N(H) =
-4.87+/-0.03 and log N(Fe)/N(H) = -5.27+/-0.05. Our derived sulfur abundance is
in excellent agreement with recent solar system determinations of Asplund,
Grevesse, & Sauval, but -0.14 dex below the solar system abundance typically
adopted in studies of the ISM. The iron abundance is ~-0.7 dex below the solar
system abundance, consistent with significant depletion. Abundance estimates
derived by simply comparing S II and Fe II to H I are +0.17 and +0.11 dex
higher, respectively, than our measurements. Ionization corrections to the
gas-phase abundances measured in the standard way are, therefore, significant
compared with the measurement uncertainties along this sight line. The
systematic uncertainties associated with the uncertain contribution to the
electron column density from ionized helium could raise these abundances by
<+0.03 dex (+7%). [Abridged]


title: Cosmic Structure Formation at Low and High Redshifts

abstract:
  The currently standard theory of cosmic structure formation posits that the
present-day clumpy appearance of the universe developed through gravitational
amplification of the matter density fluctuations that are generated in the very
early universe. The energy content of the univese and the basic statistics of
the initial density field have been determined with a reasonable accuracy from
recent observations of the cosmic microwave background, large-scale structure,
and distant supernovae. It has become possible to make accurate predictions
from the standard model. We review the latest observations and the recent
progress in the theory of structure formation at low and high redshifts. Two
promising methods to probe large-scale matter distribution are introduced and
the future prospects are discussed. Results from state-of-the-art cosmological
simulations are also presented.


title: Oxygen Recombination Line Abundances in Gaseous Nebulae

abstract:
  The determination of the heavy element abundances from giant extragalactic H
II regions has been generally based on collisionally excited lines. We will
discuss the reasons to study the characteristics of recombination lines, and
then use these lines to determine chemical abundances. Of these lines the
oxygen (specifically the O II) lines are the most important; and, of them, the
lines of multiplet 1 of O II are the most accessible. It has often been assumed
that by measuring the intensity of a single line within a multiplet the
intensities of all the lines in the multiplet can be determined; in recent
studies we have found that the intensity ratios of lines within a multiplet can
depend on density; we will present empirical density-intensity relationships
for multiplet 1 based on recent observations of H II regions and planetary
nebulae. From observations deof H II regions we find that the critical density
for collisional redistribution of the multiplet 1 O II recombination lines
amounts to 2800 +- 500 cm-3. We point out that the O/H recombination abundances
of H II regions in the solar vicinity are in excellent agreement with the O/H
solar value, while the abundances derived from collisionally excited lines are
not. We present a calibration of Pagel's method in the 8.2 < 12 + log O/H < 8.8
range based on O recombination lines.


title:
Multi-seeded multi-mode formation of embedded clusters in the RMC:
  Structured star formation toward the south-east boundary

abstract:
  The Rosette Molecular Complex contains embedded clusters with diverse
properties and origins. We have previously explored the shell mode of formation
in the north (Regions A & B) and the massive concentrations in the ridge
(Region C). Here, we explore star formation towards the south of the complex,
Region D, based on data from the spatially complete 2 Micron All Sky Survey. We
find that stars are forming prolifically throughout this region in a highly
structured mode with both clusters and loose aggregates detected. The most
prominent cluster (Region D1) lies in the north-center. This cluster is over 20
pc to the south of the Monoceros ridge, the interface of the emerging young OB
cluster NGC 2244 with its ambient molecular clouds. In addition, there are
several branches stemming from AFGL 961 in Region C and extending to the
south-east boundary of the cloud. We invoke a tree model to interpret this
pattern, corresponding to probable tracks of abrupt turbulent excitation and
subsequent decay. Alternatively, we discuss gravoturbulent collapse scenarios
based on numerical simulations. Relative stellar ages and gas flow directions
will differentiate between these mechanisms.


title:
Coherent Curvature Radiation and Proton Counterflow in the Pulsar
  Magnetosphere

abstract:
  In the proton counterflow model of a pulsar magnetosphere that we have
recently proposed, non-relativistic protons are supplied from the magnetosphere
to flow toward the pulsar surface and screen an electric field above the polar
cap region. In this Letter, we show that the proton counterflow is also
suitable for the bunching of pair plasma. The two-stream instability is easily
excited and can produce bunches of pairs with a relevant length scale to emit
coherent curvature radiation.


title: The Origins of Two Classes of Carbon-Enhanced, Metal-Poor Stars

abstract:
  We have compiled composition, luminosity, and binarity information for
carbon-enhanced, metal-poor (CEMP) stars reported by recent studies. We divided
the CEMP star sample into two classes, having high and low abundances,
respectively, of the s-process elements, and consider the abundances of several
isotopes, in particular 12C, 13C, and 14N, as well as the likely evolutionary
stages of each star. Despite the fact that objects in both groups were selected
from the same surveys (primarily the HK survey), without a-priori knowledge of
their s-process element abundances, we identify the following remarkable
difference between the two classes: s-element-rich CEMP (CEMP-s) stars occupy a
wide range of evolutionary states, but do not have a strongly evolved 13C/14N
ratio, whereas s-element-normal CEMP stars (CEMP-no) are found only high up the
first-ascent giant branch, and possess 13C/14N ratios approaching the CN-cycle
equilibrium value. Based on these observational facts, we discuss scenarios of
formation of CEMP stars.


title: Dating Secular Evolution: Bar Ages from Stellar Kinematics

abstract:
  The last few years witnessed a change of perspective in the context of galaxy
formation and evolution. The major role played by bars in the history of these
fundamental building blocks of our universe was finally realized. However, and
despite the fact that one of the major concerns of any physical science is to
measure timescales for natural phenomena, we have as yet no established way to
estimate the ages of these important galactic components. In this contribution
we outline the method we developed to estimate bar ages and briefly describe
its first results.


title: Gravitational Microlensing by Rotating Stars

abstract:
  Using the astrometry of microlensing events we study the effect of angular
momentum as compared to that of the parallax. For a rotating lens it is shown
that the effect of the angular momentum deviates the center of images from that
in the simple standard microlensing. This effect could be observed by future
astrometry missions such as GAIA and SIM for lenses with angular momentum
$S\gtrsim \times 10^{48} kg m^2 sec^{-1}$. It is shown that for extreme black
hole lenses the corresponding mass should be more than $10^3 M_{\odot}$.


title:
Self-Consistent MHD Modeling of a Coronal Mass Ejection, Coronal
  Dimming, and a Giant Cusp-Shaped Arcade Formation

abstract:
  We performed magnetohydrodynamic simulation of coronal mass ejections (CMEs)
and associated giant arcade formations, and the results suggested new
interpretations of observations of CMEs. We performed two cases of the
simulation: with and without heat conduction. Comparing between the results of
the two cases, we found that reconnection rate in the conductive case is a
little higher than that in the adiabatic case and the temperature of the loop
top is consistent with the theoretical value predicted by the Yokoyama-Shibata
scaling law. The dynamical properties such as velocity and magnetic fields are
similar in the two cases, whereas thermal properties such as temperature and
density are very different.In both cases, slow shocks associated with magnetic
reconnectionpropagate from the reconnection region along the magnetic field
lines around the flux rope, and the shock fronts form spiral patterns. Just
outside the slow shocks, the plasma density decreased a great deal. The soft
X-ray images synthesized from the numerical results are compared with the soft
X-ray images of a giant arcade observed with the Soft X-ray Telescope aboard
{\it Yohkoh}, it is confirmed that the effect of heat conduction is significant
for the detailed comparison between simulation and observation. The comparison
between synthesized and observed soft X-ray images provides new interpretations
of various features associated with CMEs and giant arcades.


title:
Comparison of the Halpha equivalent width of HII regions in a flocculent
  and a grand design galaxy: possible evidences for IMF variations

abstract:
  We present here a study of the Halpha equivalent widths of the flocculent
galaxy NGC 4395 and the grand design galaxy NGC 5457. A difference between the
mean values of the Halpha equivalent widths for the two galaxies has been
found. Several hypotheses are presented in order to explain this difference:
differences in age, metallicity, star formation rate, photon leakage and
initial mass function. Various tests and Monte Carlo models are used to find
out the most probable cause of this difference. The resultsshow that the
possible cause for the difference could be a variation in the initial mass
function. This difference is such that it seems to favor a fraction of more
massive stars in the grand design galaxy when compared with the flocculent
galaxy. This could be due to a change of the environmental conditions due to a
density wave.


title: A Hot Helium Plasma in the Galactic Center Region

abstract:
  Recent X-ray observations by the space mission Chandra confirmed the
astonishing evidence for a diffuse, hot, thermal plasma at a temperature of 9.
$10^7$ K (8 keV) found by previous surveys to extend over a few hundred parsecs
in the Galactic Centre region. This plasma coexists with the usual components
of the interstellar medium such as cold molecular clouds and a soft (~0.8 keV)
component produced by supernova remnants, and its origin remains uncertain.
First, simple calculations using a mean sound speed for a hydrogen-dominated
plasma have suggested that it should not be gravitationally bound, and thus
requires a huge energy source to heat it in less than the escape time. Second,
an astrophysical mechanism must be found to generate such a high temperature.
No known source has been identified to fulfill both requirements. Here we
address the energetics problem and show that the hot component could actually
be a gravitationally confined helium plasma. We illustrate the new prospects
this opens by discussing the origin of this gas, and by suggesting possible
heating mechanisms.


title: Molecular Gas at High Redshift

abstract:
  The Early Universe Molecular Emission Line Galaxies (EMGs) are a population
of galaxies with only 36 examples that hold great promise for the study of
galaxy formation and evolution at high redshift. The classification, luminosity
of molecular line emission, molecular mass, far-infrared (FIR) luminosity, star
formation efficiency, morphology, and dynamical mass of the currently known
sample are presented and discussed. The star formation rates derived from the
FIR luminosity range from about 300 to 5000 M(sun)per year and the molecular
mass from 4 x 10^9 to 1 x 10^{11} M(sun). At the lower end, these star
formation rates, gas masses, and diameters are similar to those of local
ultraluminous infrared galaxies, and represent starbursts in centrally
concentrated disks, sometimes, but not always, associated with active galactic
nuclei. The evidence for large (> 5 kpc) molecular disks is limited. Morphology
and several high angular resolution images suggest that some EMGs are mergers
with a massive molecular interstellar medium in both components. A critical
question is whether the EMGs, in particular those at the higher end of the gas
mass and luminosity distribution, represent the formation of massive, giant
elliptical galaxies in the early Universe. The sample size is expected to grow
explosively in the era of the Atacama Large Millimeter Array (ALMA).


title:
The Frequency Ratio Method for the seismic modelling of gamma Doradus
  stars. II The role of rotation

abstract:
  The effect of rotation on the Frequency Ratio Method (Moya et al. 2005) is
examined. Its applicability to observed frequencies of rotating gamma Doradus
stars is discussed taking into account the following aspects: the use of a
perturbative approach to compute adiabatic oscillation frequencies; the effect
of rotation on the observational Brunt-Vaisala integral determination and
finally, the problem of disentangling multiplet-like structures from frequency
patterns due to the period spacing expected for high-order gravity modes in
asymptotic regime. This analysis reveals that the FRM produces reliable results
for objects with rotational velocities up to 70 kms/s, for which the FRM
intrinsic error increases one order of magnitude with respect to the typical
FRM errors given in Moya et al. (2005). Our computations suggest that, given
the spherical degree "l" identification, the FRM may be discriminating for m =
0 modes, in the sense that the method avoids any misinterpretation induced by
the presence of rotationally split multiplet-like structures, which reinforces
the robustness of the method. However, if "l" is unknown, such discrimination
is not ensured. In order to check the FRM in presence of slow-moderate
rotation, we have applied it to the three observed frequencies of the slowly
rotating (vsini = 29 km/s) gamma Doradus star HD48501.


title:
Testing the GRB Variability/Peak Luminosity correlation using the
  pseudo-redshifts of a large sample of BATSE GRBs

abstract:
  We test the correlation found by Reichart et al. (2001) between time
variability and peak luminosity of Gamma-Ray Bursts (GRBs). Recently Guidorzi
et al. (2005) found that this still holds for a sample of 32 GRBs with
spectroscopic redshift, although with a larger scatter than that originally
found by Reichart et al. (2001). However Guidorzi et al. (2005) also found that
a power law does not provide a good description of that. We report on the same
test performed on a sample of 551 BATSE GRBs with a significant measure of
variability assuming the pseudo-redshifts derived by Band et al. (2004) (1186
GRBs) through the anticorrelation between spectral lag and peak luminosity. We
still find a correlation between variability as defined by Reichart et al.
(2001) and peak luminosity with higher significance. However, this subsample of
BATSE GRBs show a higher scatter around the best-fitting power law than that
found by Reichart et al. (2001) in the variability/peak luminosity space. This
is in agreement with the result found by Guidorzi et al. (2005) on a sample of
32 GRBs with measured redshift. These results confirm that a power law does not
provide a satisfactory description for all the GRBs, in contrast with the
original findings by Reichart et al. (2001).


title:
Do young galaxies exist in the Local Universe? - Red Giant Branch
  detection in the metal-poor dwarf SBS 1415+437

abstract:
  We present results from an HST/ACS imaging study of the metal-poor blue
compact dwarf galaxy SBS 1415+437. It has been argued previously that this is a
very young galaxy that started to form stars only less than 100 Myr ago.
However, we find that the optical color-magnitude diagram prominently reveals
asymptotic giant branch and red giant branch (RGB) stars. The brightness of the
RGB tip yields a distance of 13.6 Mpc. The color of the RGB implies that its
stars must be older than approximately 1.3 Gyr, with the exact age depending on
the assumed metallicity and dust extinction. The number of RGB stars implies
that most of the stellar mass resides in this evolved population. In view of
these and other HST results for metal-poor galaxies it seems that the local
Universe simply may not contain any galaxies that are currently undergoing
their first burst of star formation.


title: Magnetic fields in barred galaxies. IV. NGC 1097 and NGC 1365

abstract:
  We present 3.5cm and 6.2cm radio continuum maps in total and polarized
intensity of the barred galaxies NGC 1097 and NGC 1365. Both galaxies exhibit
radio ridges roughly overlapping with the massive dust lanes in the bar region.
The contrast in total intensity across the radio ridges is compatible with
compression and shear of an isotropic random magnetic field. The contrast in
polarized intensity is significantly smaller than that expected from
compression and shearing of the regular magnetic field; this could be the
result of decoupling of the regular field from the dense molecular clouds. The
regular field in the ridge is probably strong enough to reduce significantly
shear in the diffuse gas (to which it is coupled) and hence to reduce magnetic
field amplification by shearing. This contributes to the misalignment of the
observed field orientation with respect to the velocity vectors of the dense
gas. Our observations, for the first time, indicate that magnetic forces can
control the flow of the diffuse interstellar gas at kiloparsec scales. The
total radio intensity reaches its maximum in the circumnuclear starburst
regions, where the equipartition field strength is about 60\mu G, amongst the
strongest fields detected in spiral galaxies so far. The regular field in the
inner region has a spiral shape with large pitch angle, indicating the action
of a dynamo. Magnetic stress leads to mass inflow towards the centre,
sufficient to feed the active nucleus in NGC 1097. We detected diffuse X-ray
emission, possibly forming a halo of hot gas around NGC 1097.


title:
On the Orbital Evolution of Low Mass Protoplanets in Turbulent,
  Magnetised Disks

abstract:
  (Abridged).We present the results of MHD simulations of low mass protoplanets
interacting with turbulent disks. We calculate the orbital evolution of
`planetesimals' and protoplanets with masses in the range 0 < m_p < 30 M_Earth.
Planetesimals and protoplanets undergo stochastic migration due to interaction
with turbulent density fluctuations. Over run times of ~ 150 planet orbits,
stochastic migration dominates over type I migration for many models. Fourier
analysis of the torques experienced by planets indicates that the torque
fluctuations contain components with significant power whose time scales of
variation are similar to the simulation run times. These low frequency
fluctuations partly explain the dominance of stochastic torques, and may
provide a powerful means of counteracting the type I migration of some planets
in turbulent disks. Turbulence is a source of eccentricity driving.
Planetesimals attained eccentricities in the range 0.02 < e < 0.14, m_p=1
M_Earth planets attained eccentricities 0.02 < e < 0.08, and m_p=10 M_Earth
protoplanets reached 0.02 < e < 0.03. This is in basic agreement with a model
in which turbulence drives e-growth, and interaction with disk material at
coorbital Lindblad resonances causes e-damping. These results are significant
for planet formation. Stochastic migration may prevent some planet cores
migrating into their star via type I before becoming gas giants. The growth of
planetary cores may be enhanced by preventing isolation. Eccentricity
excitation by turbulence, however, may reduce growth rates of planetary cores
during the runaway and oligarchic growth stages, and cause collisions between
planetesimals to become destructive.


title:
Can variability account for apparent age spreads in OB association
  colour-magnitude diagrams?

abstract:
  We have investigated the role of photometric variability in causing the
apparent age spreads observed in the colour-magnitude diagrams of OB
associations. We have found that the combination of binarity, photometric
uncertainty and variability on timescales of a few years is not sufficient to
explain the observed spread in either of the OB associations we have studied.
Such effects can account for about half the observed spread in the sigma
Orionis subgroup and about 1/20 of the observed spread in Cep OB3b. This rules
out variability caused by stellar rotation and rotation of structures within
inner accretion discs as the source of the majority of the the apparent age
spreads. We also find that the variability tends to move objects parallel to
isochrones in V/V-i' CMDs, and thus has little influence on apparent age
spreads. We conclude that the remaining unexplained spread either reflects a
true spread in the ages of the PMS objects or arises as a result of longer term
variability associated with changes in accretion flow.


title: Gravitational Mesoscopic Constraints in Cosmological Dark Matter Halos

abstract:
  We present an analysis of the behaviour of the `coarse-grained'
(`mesoscopic') rank partitioning of the mean energy of collections of particles
composing virialized dark matter halos in a Lambda-CDM cosmological simulation.
We find evidence that rank preservation depends on halo mass, in the sense that
more massive halos show more rank preservation than less massive ones. We find
that the most massive halos obey Arnold's theorem (on the ordering of the
characteristic frequencies of the system) more frequently than less massive
halos. This method may be useful to evaluate the coarse-graining level (minimum
number of particles per energy cell) necessary to reasonably measure signatures
of `mesoscopic' rank orderings in a gravitational system.


title: Phase Transitions in a Dusty Plasma with Two Distinct Particle Sizes

abstract:
  In semiconductor manufacturing, contamination due to particulates
significantly decreases the yield and quality of device fabrication, therefore
increasing the cost of production. Dust particle clouds can be found in almost
all plasma processing environments including both plasma etching devices and in
plasma deposition processes. Dust particles suspended within such plasmas will
acquire an electric charge from collisions with free electrons in the plasma.
If the ratio of inter-particle potential energy to the average kinetic energy
is sufficient, the particles will form either a liquid structure with short
range ordering or a crystalline structure with long range ordering. Otherwise,
the dust particle system will remain in a gaseous state. Many experiments have
been conducted over the past decade on such colloidal plasmas to discover the
character of the systems formed, but more work is needed to fully understand
these structures. The preponderance of previous experiments used monodisperse
spheres to form complex plasma systems.


title: RHESSI images and spectra of two small flares

abstract:
  We studied the evolution of two small flares (GOES class C2 and C1) that
developed in the same active region with different morphological
characteristics: one is extended and the other is compact. We analyzed the
accuracy and the consistency of different algorithms implemented in RHESSI
software to reconstruct the image of the emitting sources, for energies between
3 and 12 keV. We found that all tested algorithms give consistent results for
the peak position whil the other parameters can differ at most by a factor 2.
Pixon and Forward-fit generally converge to similar results but Pixon is more
reliable for reconstructing a complex source. We investigated the spectral
characteristics of the two flares during their evolution in the 3--25 keV
energy band. We found that a single thermal model of the photon spectrum is
inadequate to fit the observations and we needed to add either a non-thermal
model or a hot thermal one.The non-thermal and the double thermal fits are
comparable. If we assume a non-thermal model, the non-thermal energy is always
higher than the thermal one.Only during the very final decay phase a single
thermal model fits fairly well the observed spectrum.


title: Variable Chaplygin Gas: Constraints from CMBR and SNe Ia

abstract:
  We constrain the parameters of the variable Chaplygin gas model, using the
location of peaks of the CMBR spectrum and SNe Ia ``gold '' data set. Equation
of state of the model is $P=-A(a)/\rho$, where $A(a)=A_0 a^{-n}$ is a positive
function of the cosmological scale factor $a$, $A_0$ and $n$ being constants.
The variable Chaplygin gas interpolates from dust-dominated era to quintessence
dominated era. The model is found to be compatible with current type Ia
Supernovae data and location of first peak if the values of $\Omega_m$ and $n$
lie in the interval $[0.017,~0.117]$ and $[-1.3,~2.6]$ respectively.


title: The Submillimeter Array Antennas and Receivers

abstract:
  The Submillimeter Array (SMA) was conceived at the Smithsonian Astrophysical
Observatory in 1984 as a six element interferometer to operate in the major
atmospheric windows from about 200 to 900 GHz. In 1996, the Academica Sinica
Institute of Astronomy and Astrophysics of Taiwan joined the project and agreed
to provide additional hardware to expand the interferometer to eight elements.
All eight antennas are now operating at the observatory site on Mauna Kea, and
astronomical observations have been made in the 230, 345, and 650 GHz bands.
  The SMA antennas have a diameter of 6 m, a surface accuracy of better than 25
micron rms, and can be reconfigured to provide spatial resolutions down to
about 0.5" at 200 GHz and, eventually, 0.1" at 850 GHz. Coupling to the
receiver package within each antenna is achieved via a beam waveguide, in a
bent Nasmyth configuration, comprised of a flat tertiary mirror and two
ellipsoidal mirrors that form a secondary pupil used for receiver calibration.
An additional fixed mirror and a rotating wire grid polarizer are then used for
receiver selection. Each antenna houses a single cryostat, with an integrated
cryocooler capable of cooling up to eight receivers to 4 K. In the current
configuration only three receiver bands are available: 175-255 GHz, 250-350
GHz, and 600-720 GHz, and simultaneous operation of the 650 GHz receiver with
either of the lower frequency receivers is possible. Eventually dual
polarization will be available from 325-350 GHz, and dual frequency operation
will be possible, pairing either of the lower frequency receivers with any of
the high frequency units: 325-425 GHz, 425-510 GHz, 600-720 GHz, and 800-900
GHz. (Abridged)


title:
Eccentricity of supermassive black hole binaries coalescing from gas
  rich mergers

abstract:
  Angular momentum loss to circumbinary gas provides a possible mechanism for
overcoming the `last parsec' problem and allowing the most massive black hole
binaries formed from galactic mergers to coalesce. Here, we show that if gas
disks also catalyze the merger of the somewhat lower mass binaries detectable
with the Laser Interferometer Space Antenna (LISA), then there may be a purely
gravitational wave signature of the role of gas in the form of a small but
finite eccentricity just prior to merger. Numerical simulations suggest that
eccentricity, excited by the interaction between the binary and surrounding gas
disk, is only partially damped during the final phase of gravitational
radiation-driven inspiral. We estimate that the typical eccentricity at one
week prior to coalescence is of the order of 0.01. Higher terminal
eccentricities, which can approach 0.1, are possible if the binary has an
extreme mass ratio. The detection of even a small eccentricity prior to merger
by LISA provides a possible discriminant between gas-driven inspirals and those
effected by stellar processes.


title: Accretion in Strong Gravity: From Galactic to Supermassive Black Holes

abstract:
  The galactic black hole binary systems give an observational template showing
how the accretion flow changes as a function of increasing mass accretion rate,
or L/L_Edd. These data can be synthetised with theoretical models of the
accretion flow to give a coherent picture of accretion in strong gravity, in
which the major hard-soft spectral transition is triggered by a change in the
nature and geometry of the inner accretion flow from a hot, optically thin
plasma to a cool, optically thick accretion disc. However, a straightforward
application of these models to AGN gives clear discrepancies in overall
spectral shape. Either the underlying accretion model is wrong, despite its
success in describing the Galactic systems and/or there is additional physics
which breaks the simple scaling from stellar to supermassive black holes.


title: Prompt Optical Detection of GRB 050401 with ROTSE-IIIa

abstract:
  The ROTSE-IIIa telescope at Siding Spring Observatory, Australia, detected
prompt optical emission from Swift GRB 050401. In this letter, we present
observations of the early optical afterglow, first detected by the ROTSE-IIIa
telescope 33 s after the start of gamma-ray emission, contemporaneous with the
brightest peak of this emission. This GRB was neither exceptionally long nor
bright. This is the first prompt optical detection of a GRB of typical duration
and luminosity. We find that the early afterglow decay does not deviate
significantly from the power-law decay observable at later times, and is
uncorrelated with the prompt gamma-ray emission. We compare this detection with
the other two GRBs with prompt observations, GRB 990123 and GRB 041219a. All
three bursts exhibit quite different behavior at early times.


title: High Energy Cosmic Rays from Local GRBs

abstract:
  We have developed a model that explains cosmic rays with energies E between
\~0.3 PeV and the energy of the second knee at E_2 ~ 3*10^{17} eV as
originating from a recent Galactic gamma-ray burst (GRB) that occurred ~1 Myr
ago within 1 kpc from Earth. Relativistic shocks from GRBs are assumed to
inject power-law distributions of cosmic rays (CRs) to the highest energies.
Diffusive propagation of CRs from the local GRB explains the CR spectrum near
and above the first knee at E_1 ~ 3*10^{15} eV. The first and the second knees
are explained as being directly connected with the injection of plasma
turbulence in the interstellar medium on a ~1 pc and ~100 pc scales,
respectively. Transition to CRs from extragalactic GRBs occurs at E > E_2. The
origin of the ankle in the CR spectrum at E ~ 4*10^{18} eV is due to photopair
energy losses of UHECRs on cosmological timescales, as also suggested by
Berezinsky and collaborators. Any significant excess flux of extremely high
energy CRs deviating from the exponential cutoff behavior at E> E_{GZK} =
6*10^{19} eV would imply a significant contribution due to recent GRB activity
on timescales t < 10^8 yrs from local extragalactic sources within ~10 Mpc.


title:
The Shape of Dark Matter Halos: Dependence on Mass, Redshift, Radius,
  and Formation

abstract:
  Using six high resolution dissipationless simulations with a varying box size
in a flat LCDM universe, we study the mass and redshift dependence of dark
matter halo shapes for M_vir = 9.0e11 - 2.0e14, over the redshift range z=0-3,
and for two values of sigma_8=0.75 and 0.9. Remarkably, we find that the
redshift, mass, and sigma_8 dependence of the mean smallest-to-largest axis
ratio of halos is well described by the simple power-law relation <s> = (0.54
+- 0.02)(M_vir/M_*)^(-0.050 +- 0.003), where s is measured at 0.3 R_vir and the
z and sigma_8 dependences are governed by the characteristic nonlinear mass,
M_*=M_*(z,sigma_8). We find that the scatter about the mean s is well described
by a Gaussian with sigma ~ 0.1, for all masses and redshifts. We compare our
results to a variety of previous works on halo shapes and find that reported
differences between studies are primarily explained by differences in their
methodologies. We address the evolutionary aspects of individual halo shapes by
following the shapes of the halos through ~100 snapshots in time. We determine
the formation scalefactor a_c as defined by Wechsler et al. (2002) and find
that it can be related to the halo shape at z = 0 and its evolution over time.


title:
Coherent Radiation in Gamma-Ray Bursts and Relativistic Collisionless
  Shocks

abstract:
  We suggest that coherent radiation may occur in relativistic collisionless
shocks via two-stream Weibel instabilities. The coherence amplifies the
radiation power by many orders [$\sim 10^{12}$ in Gamma-Ray Bursts (GRBs)] and
particles cool very fast before being randomized. We imply (1) GRBs accompany
strong infrared emission, (2) protons efficiently transfer energy to electrons
and (3) prompt GRBs might be the upscattered coherent radiation.


title: A Very High Energy Gamma-Ray Spectrum of 1ES 2344+514

abstract:
  The BL Lacertae (BL Lac) object 1ES 2344+514 (1ES 2344), at a redshift of
0.044, was discovered as a source of very high energy (VHE) gamma rays by the
Whipple Collaboration in 1995 \citep{2344Catanese98}. This detection was
recently confirmed by the HEGRA Collaboration \citep{2344Hegra03}. As is
typical for high-frequency peaked blazars, the VHE gamma-ray emission is highly
variable. On the night of 20 December, 1995, a gamma-ray flare of 5.3-sigma
significance was detected, the brightest outburst from this object to-date. The
emission region is compatible with a point source. The spectrum between 0.8 TeV
and 12.6 TeV can be described by a power law $\frac{\ud^3 N}{\ud E \ud A \ud
t}=(5.1\pm1.0_{st}\pm1.2_{sy})\times10^{-7} (E/ \mathrm{TeV})^{-2.54
\pm0.17_{st}\pm0.07_{sy}} \mathrm{\frac{1}{TeV m^2 s}}$. Comparing the spectral
index with that of the other five confirmed TeV blazars, the spectrum of 1ES
2344 is similar to 1ES 1959+650, located at almost the same distance. The
spectrum of 1ES 2344 is steeper than the brightest flare spectra of Markarian
421 (Mrk~421) and Markarian 501 (Mrk~501), both located at a distance about 2/3
that of 1ES 2344, and harder than the spectra of PKS 2155-304 and H~1426+428,
which are located almost three times as far. This trend is consistent with
attenuation caused by the infrared extragalactic background radiation.


title: Rotation and variability of young very low mass objects

abstract:
  Variability studies are an important tool to investigate key properties of
stars and brown dwarfs. From photometric monitoring we are able to obtain
information about rotation and magnetic activity, which are expected to change
in the mass range below 0.3 solar masses, since these fully convective objects
cannot host a solar-type dynamo. On the other hand, spectroscopic variability
information can be used to obtain a detailed view on the accretion process in
very young objects. In this paper, we report about our observational efforts to
analyse the variability and rotational evolution of young brown dwarfs and very
low mass stars.


title:
A Census of Object Types and Redshift Estimates in the SDSS Photometric
  Catalog from a Trained Decision-Tree Classifier

abstract:
  We have applied ClassX, an oblique decision tree classifier optimized for
astronomical analysis, to the homogeneous multicolor imaging data base of the
Sloan Digital Sky Survey (SDSS), training the software on subsets of SDSS
objects whose nature is precisely known via spectroscopy. We find that the
software, using photometric data only, correctly classifies a very large
fraction of the objects with existing SDSS spectra, both stellar and
extragalactic. ClassX also accurately predicts the redshifts of both normal and
active galaxies in SDSS. To illustrate ClassX applications in SDSS research, we
(a) derive the object content of the SDSS DR2 photometric catalog and (b)
provide a sample catalog of resolved SDSS objects that contains a large number
of candidate AGN galaxies, 27,000, along with 63,000 candidate normal galaxies
at magnitudes substantially fainter than typical magnitudes of SDSS
spectroscopic objects. The surface density of AGN selected by ClassX to i~19 is
in agreement with that quoted by SDSS. When ClassX is applied to the
photometric data fainter than the SDSS spectroscopic limit, the inferred
surface density of AGN rises sharply, as expected. The ability of the
classifier to accurately constrain the redshifts of huge numbers (ultimately ~
10^7) of active galaxies in the photometric data base promises new insights
into fundamental issues of AGN research, such as the evolution of the AGN
luminosity function with cosmic time, the starburst--AGN connection, and
AGN--galactic morphology relationships.


title: Shearing Box Simulations of the MRI in a Collisionless Plasma

abstract:
  We describe local shearing box simulations of turbulence driven by the
magnetorotational instability (MRI) in a collisionless plasma. Collisionless
effects may be important in radiatively inefficient accretion flows, such as
near the black hole in the Galactic Center. The MHD version of ZEUS is modified
to evolve an anisotropic pressure tensor. A fluid closure approximation is used
to calculate heat conduction along magnetic field lines. The anisotropic
pressure tensor provides a qualitatively new mechanism for transporting angular
momentum in accretion flows (in addition to the Maxwell and Reynolds stresses).
We estimate limits on the pressure anisotropy due to pitch angle scattering by
kinetic instabilities. Such instabilities provide an effective ``collision''
rate in a collisionless plasma and lead to more MHD-like dynamics. We find that
the MRI leads to efficient growth of the magnetic field in a collisionless
plasma, with saturation amplitudes comparable to those in MHD. In the saturated
state, the anisotropic stress is comparable to the Maxwell stress, implying
that the rate of angular momentum transport may be moderately enhanced in a
collisionless plasma.


title: FUSE Observation of the Narrow-line Seyfert 1 Galaxy RE 1034+39

abstract:
  We present analysis from simultaneous FUSE, ASCA, and EUVE observations, as
well as a reanalysis of archival HST spectra, from the extreme Narrow-line
Seyfert 1 Galaxy RE 1034+39 (KUG 1031+398). RE 1034+39 has an unusually hard
spectral energy distribution (SED) that peaks in the soft X-rays. Its emission
lines are unusual in that they can all be modelled as a Lorentzian centered at
the rest wavelength with only a small range in velocity widths. In order to
investigate whether the unusual SED influences the emission line ratios and
equivalent widths, we present three complementary types of photoionization
analysis. The FUSE spectrum was particularly important because it includes the
high-ionization line OVI. First, we use the photoionization code Cloudy and the
SED developed from the coordinated observations to confirm that the emission
lines are consistent with observed hard SED. The best model parameters were an
ionization parameter log(U) ~ -2 and a hydrogen number density log(n_H)=9.75
[cm^-2]. Second, we present a Locally Optimally-emitting Cloud model. This
model produced enhanced OVI as observed, but also yielded far too strong MgII.
Third, we develop a series of semi-empirical SEDs, run Cloudy models, and
compare the results with the measured values using a figure of merit (FOM). The
FOM minimum indicates similar SED and gas properties as were inferred from the
one-zone model using the RE 1034+39 continuum. Furthermore, the FOM increases
sharply toward softer continua, indicating that a hard SED is required by the
data in the context of a one-zone model.


title: Fine structure, magnetic field and heating of sunspot penumbrae

abstract:
  We interpret penumbral filaments as due to convection in field-free, radially
aligned gaps just below the visible surface of the penumbra, intruding into a
nearly potential field above. This solves the classical discrepancy between the
large heat flux and the low vertical velocities observed in the penumbra. The
presence of the gaps causes strong small-scale fluctuations in inclination,
azimuth angle and field strength, but without strong forces acting on the gas.
The field is nearly horizontal in a region around the cusp-shaped top of the
gap, thereby providing an environment for Evershed flows. We identify this
region with the recently discovered dark penumbral cores. Its darkness has the
same cause as the dark lanes in umbral light-bridges, reproduced in numerical
simulations by Nordlund and Stein (2005). We predict that the large vertical
and horizontal gradients of the magnetic field inclination and azimuth in the
potential field model will produce the net circular polarization seen in
observations. The model also explains the significant elevation of bright
filaments above their surroundings. It predicts that dark areas in the penumbra
are of two different kinds: dark filament cores containing the most inclined
(horizontal) fields, and regions between bright filaments, containing the least
inclined field lines.


title: Astrometric Effects of Secular Aberration

abstract:
  One of the main endeavors of fundamental astrometry is to establish a
practical realization of an inertial reference frame anchored to celestial
objects whose positions are defined in the barycentric coordinates of the solar
system. The development of astrometric facilities operating from space at a
microarcsecond level of precision makes the non-uniformity of the galactic
motion of the barycenter an observable effect that violates the inertiality of
the barycentric frame. Most of the observable effect is caused by secular
acceleration of the barycenter with respect to the center of the Galaxy. The
acceleration results in a pattern of secular aberration which is observable
astrometrically as a systematic vector field of the proper motions of distant
quasars. We employ the vector spherical harmonics to describe the predicted
field of the proper motions and evaluate its amplitude at each point on the
celestial sphere. It is shown that the pattern of secular aberration is fully
represented by three low-order electric-type vector harmonics, and hence, it is
easily distinguishable from the residual rotations of the reference frame and
other possible effects, such as the hypothetical long-period gravitational
waves. Comprehensive numerical simulations of the grid astrometry with SIM
PlanetQuest are conducted. The full covariance matrix of the simulated grid
solution is used to evaluate the covariances of the three electric harmonic
coefficients, representing the secular aberration pattern of proper motions. We
conclude that the grid astrometry with SIM PlanetQuest will be sensitive to the
main galactocentric component of secular acceleration, while the peculiar
acceleration of the Sun with respect to LSR is expected to be too small to be
detected with this astrometric space interferometer.


title: The Fourth VLBA Calibrator Survey - VCS4

abstract:
  This paper presents the fourth extension to the Very Long Baseline Array
(VLBA) Calibrator Survey, containing 258 new sources not previously observed
with very long baseline interferometry (VLBI). This survey, based on three 24
hour VLBA observing sessions, fills remaining areas on the sky above
declination -40 degrees where the calibrator density is less than one source
within a 4 degree radius disk at any given direction. The share of these area
was reduced from 4.6% to 1.9%. Source positions were derived from astrometric
analysis of group delays determined at 2.3 and 8.6 GHz frequency bands using
the Calc/Solve software package. The VCS4 catalogue of source positions, plots
of correlated flux density versus projected baseline length, contour plots and
fits files of naturally weighted CLEAN images, as well as calibrated visibility
function files are available on the Web at http://gemini.gsfc.nasa.gov/vcs4 .


title:
Iron Fluorescent Line Emission from Black Hole Accretion Disks with
  Magnetic Reconnection-Heated Corona

abstract:
  We investigate the iron K$\alpha$ fluorescent line produced by hard X-ray
photons from magnetic reconnection-heated corona. The hot corona with
temperature being about $10^9$K can irradiate the underlying disk with a
continuum X-ray spectrum produced via thermal Comptonization. Then the iron
atoms in the disk photoelectrically absorb X-ray photons and radiate K$\alpha$
line photons. Therefore, the activity of corona is responsible to the iron line
emission from the underlying disk. In previous studies, oversimplified X-ray
photon sources are often assumed above the disk in order to compute the iron
line profile or power-law line emissivity profiles are assumed with an index
being a free parameter. We adopt the more realistic corona model constructed by
Liu et al. in which the corona is heated by magnetic energy released through
the reconnection of magnetic flux loops and which has no free parameter. Then
the accretion energy is dominantly dissipated in the corona, in which X-ray
photons are efficiently produced and irradiate the underlying disk. We find the
local emmisivity of iron line on the disk is approximated as $F_{{\rm
K}\alpha}(r)\propto r^{-5}$. The iron line profiles derived from this model
give excellent fits to the observational data of MCG-6-30-15 with the profiles
derived theoretically for $i\sim 30^{\circ}$ for energy band 4-7keV. Possible
origins of line variability are briefly discussed.


title:
Effects of the complex mass distribution of dark matter halos on weak
  lensing cluster surveys

abstract:
  Gravitational lensing effects arise from the light ray deflection by all of
the mass distribution along the line of sight. It is then expected that weak
lensing cluster surveys can provide us true mass-selected cluster samples. With
numerical simulations, we analyze the correspondence between peaks in the
lensing convergence $\kappa$-map and dark matter halos. Particularly we
emphasize the difference between the peak $\kappa$ value expected from a dark
matter halo modeled as an isolated and spherical one, which exhibits a
one-to-one correspondence with the halo mass at a given redshift, and that of
the associated $\kappa$-peak from simulations. For halos with the same expected
$\kappa$, their corresponding peak signals in the $\kappa$-map present a wide
dispersion. At an angular smoothing scale of $\theta_G=1\hbox{arcmin}$, our
study shows that for relatively large clusters, the complex mass distribution
of individual clusters is the main reason for the dispersion. The projection
effect of uncorrelated structures does not play significant roles. The
triaxiality of dark matter halos accounts for a large part of the dispersion,
especially for the tail at high $\kappa$ side. Thus lensing-selected clusters
are not really mass-selected. (abridged)


title:
Tidal torques, disc radius variations, and instabilities in dwarf novae
  and soft X-ray transients

abstract:
  The study of outer disc radius variations in close binary systems is
important for understanding the structure and evolution of accretion discs.
These variations are predicted by models of both quasi steady and
time-dependent discs, and these predictions can be confronted with
observations. We consider theoretical and observational consequences of such
variations in cataclysmic variables and low mass X-ray binaries. We find that
the action of tidal torques, that determine the outer radius at which the disc
is truncated, must be important also well inside the tidal radius. We conclude
that it is doubtful that the tidal-thermal instability is responsible for the
superoutburst/superhump phenomena in dwarf novae, and confirm that it cannot be
the reason for the outbursts of soft X-ray transients. It is likely that tidal
torques play a role during superoutbursts of very-low mass-ratio systems but
they cannot be the main and only cause of superhumps.


title: Identification of Two categories of optically bright gamma-ray bursts

abstract:
  We present the results of a systematical analysis of the intrinsic optical
afterglow light curves for a complete sample of gamma-ray bursts (GRBs)
observed in the period from Feb. 1997 to Aug. 2005. These light curves are
generally well-sampled, with at least four detections in the $R$ band. The
redshifts of all the bursts in the sample are available. We derive the
intrinsic $R$ band afterglow lightcurves (luminosity versus time within the
cosmic proper rest frame) for these GRBs, and discover a fact that they
essentially follow two universal tracks after 2 hours since the GRB triggers.
The optical luminosities at 1 day show a clear bimodal distribution, peaking at
1.4*10^{46} ergs~s^{-1} for the luminous group and 5.3*10^{44} ergs~s^{-1} for
the dim group. About 75% of the GRBs are in the luminous group, and the other
25% belong to the dim group. While the luminous group has a wide range of
redshift distribution, the bursts in the dim group all appear at a redshift
lower than 1.1.


title: Very low-mass members of the Lupus 3 cloud

abstract:
  We report on a multi-band survey for very low-mass stars and brown dwarfs in
the Lupus 3 cloud with the Wide Field Imager (WFI) at the ESO/MPG 2.2m
telescope on La Silla Observatory (Chile). Our multiband optical photometry is
combined with available 2MASS JHK photometry to identify 19 new young stars and
3 brown dwarf candidates as probable members of this star forming region. Our
objects are mostly clustered around the cloud core. Stars and brown dwarfs have
similar levels of H-alpha emission, probably a signature of accretion. One
object, a brown dwarf candidate, exhibits a near-infrared excess, which may
indicate the presence of a disk, but its H-alpha emission cannot be confirmed
due to its faintness in the optical passbands. We also find two visual pairs of
probable Lupus 3 members that may be wide binaries.


title: Effects of Magnetic Fields on Proto-Neutron Star Winds

abstract:
  We discuss effects of magnetic fields on proto-neutron star winds by
performing numerical simulation. We assume that the atmosphere of proto-neutron
star has a homogenous magnetic field (ranging from ~10^{12} G to ~10^{15} G)
perpendicular to the radial direction and examine the dependence of the three
key quantities (dynamical time scale, electron fraction, and entropy per
baryon) for the successful r-process on the magnetic field strength. Our
results show that even with a magneter-class field strength, ~10^{15} G, the
feature of the wind dynamics varies only little from that of non-magnetic
winds, and that the condition for successful r-process is not realized.


title: Crypto-baryonic Dark Matter

abstract:
  It is proposed that dark matter could consist of compressed collections of
atoms (or metallic matter) encapsulated into, for example, 20 cm big pieces of
a different phase. The idea is based on the assumption that there exists at
least one other phase of the vacuum degenerate with the usual one. Apart from
the degeneracy of the phases we only assume Standard Model physics. The other
phase has a Higgs VEV appreciably smaller than in the usual electroweak vacuum.
The balls making up the dark matter are very difficult to observe directly, but
inside dense stars may expand eating up the star and cause huge explosions
(gamma ray bursts). The ratio of dark matter to ordinary baryonic matter is
expressed as a ratio of nuclear binding energies and predicted to be about 5.


title:
Fast spin +-2 spherical harmonics transforms and application in
  cosmology

abstract:
  A fast and exact algorithm is developed for the spin +-2 spherical harmonics
transforms on equi-angular pixelizations on the sphere. It is based on the
Driscoll and Healy fast scalar spherical harmonics transform. The theoretical
exactness of the transform relies on a sampling theorem. The associated
asymptotic complexity is of order O(L^2 log^2_2(L)), where 2L stands for the
square-root of the number of sampling points on the sphere, also setting a band
limit L for the spin +-2 functions considered. The algorithm is presented as an
alternative to existing fast algorithms with an asymptotic complexity of order
O(L^3) on other pixelizations. We also illustrate these generic developments
through their application in cosmology, for the analysis of the cosmic
microwave background (CMB) polarization data.


title: Discovery and study of the accreting pulsar 2RXP J130159.6-635806

abstract:
  We report on analysis of the poorly studied source 2RXP J130159.6-635806 at
different epochs with ASCA, Beppo-SAX, XMM-Newton, and INTEGRAL. The source
shows coherent X-ray pulsations at a period ~700s with an average spin up rate
of about dnu/dt ~ 2x10^{-13} Hz/s. A broad band (1-60 keV) spectral analysis of
2RXP J130159.6-635806 based on almost simultaneous XMM-Newton and INTEGRAL data
demonstrates that the source has a spectrum typical of an accretion powered
X-ray pulsar, i.e. an absorbed power law with a high energy cut-off with a
photon index Gamma ~ 0.5-1.0 and a cut-off energy of ~25 keV. The long term
behaviour of the source, its spectral and timing properties, tend to indicate a
high mass X-ray binary with Be companion. We also report on the identification
of the likely infrared counterpart to 2RXP J130159.6-635806. The interstellar
reddening does not allow us to strongly constrain the spectral type of the
counterpart. The latter is, however, consistent with a Be star, the kind of
which is often observed in accretion powered X-ray pulsars.


title: Fast directional correlation on the sphere with steerable filters

abstract:
  A fast algorithm is developed for the directional correlation of scalar
band-limited signals and band-limited steerable filters on the sphere. The
asymptotic complexity associated to it through simple quadrature is of order
O(L^5), where 2L stands for the square-root of the number of sampling points on
the sphere, also setting a band limit L for the signals and filters considered.
The filter steerability allows to compute the directional correlation uniquely
in terms of direct and inverse scalar spherical harmonics transforms, which
drive the overall asymptotic complexity. The separation of variables technique
for the scalar spherical harmonics transform produces an O(L^3) algorithm
independently of the pixelization. On equi-angular pixelizations, a sampling
theorem introduced by Driscoll and Healy implies the exactness of the
algorithm. The equi-angular and HEALPix implementations are compared in terms
of memory requirements, computation times, and numerical stability. The
computation times for the scalar transform, and hence for the directional
correlation, of maps of several megapixels on the sphere (L~10^3) are reduced
from years to tens of seconds in both implementations on a single standard
computer. These generic results for the scale-space signal processing on the
sphere are specifically developed in the perspective of the wavelet analysis of
the cosmic microwave background (CMB) temperature (T) and polarization (E and
B) maps of the WMAP and Planck experiments. As an illustration, we consider the
computation of the wavelet coefficients of a simulated temperature map of
several megapixels with the second Gaussian derivative wavelet.


title:
Primordial binaries and intermediate mass black holes in globular
  clusters

abstract:
  We present the first study of the dynamical evolution of a star cluster that
combines a significant population of primordial binaries with the presence of a
central black hole. We use direct N-body simulations, with a black hole mass of
about one percent of the total mass of the cluster.
  The evolution of the binary population is strongly influenced by the presence
of the black hole, which gives the cluster a large core with a central density
cusp. Starting from a Plummer profile, we first encounter a phase, that last
approximately 10 half-mass relaxation times, in which binaries are disrupted
faster compared to analogous simulations without a black hole. Subsequently,
however, binary disruption slows down significantly, due to the large core
size.
  The dynamical interplay between the primordial binaries and the black hole
thus introduces new features with respect to the scenarios investigated so far,
where the influence of the black hole and of the binaries have been considered
separately. Specifically, the pattern of binary destruction by an
intermediate-mass black hole may leave a fingerprint that could be detected
observationally.


title:
Limits to the muon flux from neutralino annihilations in the Sun with
  the AMANDA detector

abstract:
  A search for an excess of muon-neutrinos from neutralino annihilations in the
Sun has been performed with the AMANDA-II neutrino detector using data
collected in 143.7 days of live-time in 2001. No excess over the expected
atmospheric neutrino background has been observed. An upper limit at 90%
confidence level has been obtained on the annihilation rate of captured
neutralinos in the Sun, as well as the corresponding muon flux limit at the
Earth, both as functions of the neutralino mass in the range 100 GeV-5000 GeV.


title: M82, Starbursts, Star Clusters, and the Formation of Globular Clusters

abstract:
  We observed the nearby starburst galaxy M82 in CO in the higher frequency
(2--1) transition to achieve an angular resolution below 1 arc second or 17 pc
at the target. We resolved the molecular gas into a large number of compact
clouds, with masses ranging from about 2x10^3 to 2x10^6 solar masses. The mass
spectrum scales as N(M) ~ M^-1.5, similar to the mass spectra of young massive
star clusters suggesting that individual molecular clouds are transformed in
the starburst into individual star clusters. The larger clouds are surrounded
by supernovae and HII regions suggesting that star formation proceeds from the
outside of the clouds and progresses inward consistent with triggering by a
sudden increase in external pressure. The clouds with internal star formation
have velocity gradients and inverse P-Cygni spectral line profiles indicating
inward motions of 35 kms consistent with shock driven compression. Diffuse
free-free radio emission and X-ray emission around the clouds provides evidence
for superheated ionized gas sufficient to drive the compression. Clouds with
spectral lines indicating expansion show little internal star formation
suggesting that the dynamics precedes and is responsible for the star formation
rather than the inverse. M82 is known to be in interaction with neighboring
M81. The overall picture is consistent with the formation of massive star
clusters from individual giant molecular clouds crushed by a sudden galactic
scale increase in external pressure generated by the changing dynamics that
result from a near-collision with a neighboring galaxy. Present day globular
clusters may have formed in a similar fashion in primordial galaxies.


title:
Nearby early-type galaxies with ionized gas.II. Line-strength indices
  for 18 additional galaxies

abstract:
  Rampazzo et al. 2005 (Paper I) presented a data-set of line-strength indices
for 50 early-type galaxies in the nearby Universe. The galaxy sample is biased
toward galaxies showing emission lines, located in environments corresponding
to a broad range of local galaxy densities, although predominantly in low
density environments. The present addendum to Paper I enlarges the above
data-set of line-strength indices by analyzing 18 additional early-type
galaxies (three galaxies, namely NGC 3607, NGC 5077 and NGC 5898 have been
already presented in the previous set). As in Paper I, we measured 25
line-strength indices, defined by the Lick IDS "standard" system (Trager et al.
1998; Worthey & Ottaviani 1997), for 7 luminosity weighted apertures and 4
gradients of each galaxy. This paper presents the line-strength data-set and
compares it with the available data in the literature.


title: X-ray Variability Characteristics of the Seyfert 1 Galaxy NGC 3783

abstract:
  We have characterized the energy-dependent X-ray variability properties of
the Seyfert~1 galaxy NGC 3783 using archival XMM-Newton and Rossi X-ray Timing
Explorer data. The high-frequency fluctuation power spectral density function
(PSD) slope is consistent with flattening towards higher energies. Light curve
cross correlation functions yield no significant lags, but peak coefficients
generally decrease as energy separation of the bands increases on both short
and long timescales. We have measured the coherence between various X-ray bands
over the temporal frequency range of 6e-8 to 1e-4 Hz; this range includes the
temporal frequency of the low-frequency power spectral density function (PSD)
break tentatively detected by Markowitz et al. and includes the lowest temporal
frequency over which coherence has been measured in any AGN to date. Coherence
is generally near unity at these temporal frequencies, though it decreases
slightly as energy separation of the bands increases. Temporal
frequency-dependent phase lags are detected on short time scales; phase lags
are consistent with increasing as energy separation increases or as temporal
frequency decreases. All of these results are similar to those obtained
previously for several Seyfert galaxies and stellar-mass black hole systems.
Qualitatively, these results are consistent with the variability models of
Kotov et al. and Lyubarskii, wherein the X-ray variability is due to inwardly
propagating variations in the local mass accretion rate.


title: A simulation pipeline for the Planck mission

abstract:
  We describe an assembly of numerical tools to model the output data of the
Planck satellite. These start with the generation of a CMB sky in a chosen
cosmology, add in various foreground sources, convolve the sky signal with
arbitrary, even non-symmetric and polarised beam patterns, derive the time
ordered data streams measured by the detectors depending on the chosen
satellite-scanning strategy, and include noise signals for the individual
detectors and electronic systems. The simulation products are needed to
develop, verify, optimise, and characterise the accuracy and performance of all
data processing and scientific analysis steps of the Planck mission, including
data handling, data integrity checking, calibration, map making, physical
component separation, and power spectrum estimation. In addition, the
simulations allow detailed studies of the impact of many stochastic and
systematic effects on the scientific results. The efficient implementation of
the simulation allows the build-up of extended statistics of signal variances
and co-variances.
  Although being developed specifically for the Planck mission, it is expected
that the employed framework as well as most of the simulation tools will be of
use for other experiments and CMB-related science in general.


title: CH 3 GHz Observations of the Galactic Center

abstract:
  A 3 $\times$ 3 map of the Galactic Center was made at 9$\arcmin$ resolution
and 10$\arcmin$ spacing in the CH $^2\Pi_{1/2}$, J=1/2, F=1-1 transition at
3335 MHz. The CH emission shows a velocity extent that is nearly that of the
CO(1-0) line, but the CH line profiles differ markedly from the CO. The 3335
MHz CH transition primarily traces low-density molecular gas and our
observations indicate that the mass of this component within $\sim$ 30 pc of
the Galactic Center is $\sim$ 9 $\times$ 10$^6$ M$_\odot$. The CO-H$_2$
conversion factor obtained for the low-density gas in the mapped region is
greater than that thought to apply to the dense molecular gas at the Galactic
Center. In addition to tracing the low-density molecular gas at the Galactic
Center, the CH spectra show evidence of emission from molecular clouds along
the line of sight both in the foreground and background. The scale height of
these clouds ranges from 27 - 109 pc, consistent with previous work based on
observations of molecular clouds in the inner Galaxy.


title: XMM-Newton spectroscopy of high-redshift QSOs

abstract:
  XMM-Newton observations of 29 high redshift (z>2) quasars, including seven
radio-quiet, 16 radio-loud and six Broad Absorption Line (BAL) objects, are
presented; due to the high redshifts, the rest-frame energy bands extend up to
\~30-70 keV. Over 2-10 keV, the quasars can be well fitted in each case by a
simple power-law, with no strong evidence for iron emission lines. The lack of
iron lines is in agreement both with dilution by the radio jet emission (for
the radio-loud quasars) and the X-ray Baldwin effect. No Compton reflection
humps at higher energies (i.e., above 10 keV in the rest frame) are detected
either. Over the broad-band (0.3-10 keV), approximately half (nine out of 16)
of the radio-loud quasars are intrinsically absorbed, with the values of N_H
generally being 1-2 x 10^22 cm^-2 in the rest frames of the objects. None of
the seven radio-quiet objects shows excess absorption, while four of the six
BAL quasars are absorbed. The radio-loud quasars have flatter continuum slopes
than their radio-quiet counterparts (Gamma_RL ~ 1.55; Gamma_RQ ~ 1.98 over 2-10
keV), while, after modelling the absorption, the underlying photon index for
the six BAL quasars is formally consistent with the non-BAL radio-quiet
objects.


title:
Can we ignore magnetic fields in studies of PN formation, shaping and
  interaction with the ISM?

abstract:
  Yes.
  (As this paper summarizes my talk at the Planetary Nebulae As Astronomical
Tools meeting [Gdansk, June 2005], I stay as close as possible to the
presentation I gave at the Gdansk meeting. Hence, the title is as was given by
the organizers, and the abstract is my original one.)


title:
The effects of Population III stars and variable IMF on the chemical
  evolution of the Galaxy

abstract:
  We studied the effects of a hypothetical initial stellar generation (PopIII)
of only massive and very massive stars (VMS) on the chemical evolution of the
Galaxy. We adopted the two-infall chemical evolution model of Chiappini et al.
and tested several sets of yields for primordial VMS (Pair-Creation SNe), which
produce different amounts of heavy elements than lower mass stars. We focused
on the evolution of alpha-elements, C, N, Fe. The effects of PopIII stars on
the Galactic evolution of these elements is negligible if a few generations of
such stars occurred, whereas they produce different results from the standard
models if they formed for a longer period. Also the effects of a more strongly
variable IMF were discussed, making use of suggestions appeared in the
literature to explain the lack of metal-poor stars in the Galactic halo with
respect to model predictions. The predicted variations in abundances, SN rates,
G-dwarf [Fe/H] distribution are here more dramatic and in contrast with
observations; we concluded that a constant or slightly varying IMF is the best
solution. Our main conclusion is that if VMS existed they must have formed only
for a very short period of time (until the halo gas reached the threshold
metallicity for the formation of very massive objects); in this case, their
effects on the evolution of the studied elements was negligible also in the
earliest phases. We thus cannot prove or disprove the existence of such stars
on the basis of the available data. Due to their large metal production and
short lives, primordial VMS should have enriched the halo gas beyond the
metallicity of the most metal poor stars known in a few Myrs. This constrains
the number of Pair-Creation SNe: we find that a number of 2-20 of such SNe
occurred in our Galaxy depending on the stellar yields.


title: Dark cloud cores and gravitational decoupling from turbulent flows

abstract:
  We test the hypothesis that the starless cores may be gravitationally bound
clouds supported largely by thermal pressure by comparing observed molecular
line spectra to theoretical spectra produced by a simulation that includes
hydrodynamics, radiative cooling, variable molecular abundance, and radiative
transfer in a simple one-dimensional model. The results suggest that the
starless cores can be divided into two categories: stable starless cores that
are in approximate equilibrium and will not evolve to form protostars, and
unstable pre-stellar cores that are proceeding toward gravitational collapse
and the formation of protostars. The starless cores might be formed from the
interstellar medium as objects at the lower end of the inertial cascade of
interstellar turbulence. Additionally, we identify a thermal instability in the
starless cores. Under par ticular conditions of density and mass, a core may be
unstable to expansion if the density is just above the critical density for the
collisional coupling of the gas and dust so that as the core expands the
gas-dust coupling that cools the gas is reduced and the gas warms, further
driving the expansion.


title:
The image separation distribution of strong lenses: Halo versus subhalo
  populations

abstract:
  We present a halo model prediction of the image separation distribution of
strong lenses. Our model takes account of the subhalo population, which has
been ignored in previous studies, as well as the conventional halo population.
Halos and subhalos are linked to central and satellite galaxies by adopting an
universal scaling relation between masses of (sub-)halos and luminosities of
galaxies. Our model predicts that 10%-20% of lenses should be caused by the
subhalo population. The fraction of lensing by satellite galaxies (subhalos)
peaks at ~1'' and decreases rapidly with increasing image separations. We
compute fractions of lenses which lie in groups and clusters, and find them to
be ~14% and ~4%, respectively: Nearly half of such lenses are expected to be
produced by satellite galaxies, rather than central parts of halos. We also
study mass distributions of lensing halos and find that even at image
separations of ~3'' the deviation of lens mass distributions from isothermal
profiles is large: At or beyond ~3'' image separations are enhanced
significantly by surrounding halos. Our model prediction agrees reasonably well
with observed image separation distributions from galaxy to cluster scales.


title: Comment on astro-ph/0507588 and astro-ph/0508483

abstract:
  Guidorzi has now written two papers (astro-ph/0507588 and astro-ph/0508483,
both accepted to MNRAS) on the GRB variability-luminosity correlation in which
he finds that expanded samples of L vs. V data are not well described by a
power law because the scatter of the data around such a model is more than can
be accounted for by the data's statistical errors alone (sample variance) --
"in contrast with the original findings by Reichart et al. (2001)" -- but then
proceeds to model these data with a power law anyway and finds significantly
shallower L vs. V relationships than Reichart et al. (2001) found. However, as
Reichart & Nysewander (2005; astro-ph/0508111) pointed out after Guidorzi's
first posting but before his second, Reichart et al. (2001) never modeled their
L vs. V data with a power law. Instead, they used a power law with a
distribution around it to accommodate and measure this sample variance.
Ignoring sample variance in a fit that requires it very easily results in
incorrect fitted parameter values due to increased sensitivity to outliers, as
well as significantly underestimated uncertainties in these fitted parameter
values. Fitting to Guidorzi's own data, Reichart & Nysewander (2005) showed
that when sample variance is included in the model, L ~ V^3.4(+0.9,-0.6) with a
sample variance of sigma_logV = 0.20(+0.04,-0.04), which is in excellent
agreement with the original finding of Reichart et al. (2001) -- L ~
V^3.3(+1.1,-0.9) with a sample variance of sigma_logV = 0.18(+0.07,-0.05) --
when the sample was approximately one-third its current size.


title: On particle acceleration and trapping by Poynting flux dominated flows

abstract:
  Using particle-in-cell (PIC) simulations, we study the evolution of a
strongly magnetized plasma slab propagating into a finite density ambient
medium. Like previous work, we find that the slab breaks into discrete magnetic
pulses. The subsequent evolution is consistent with diamagnetic relativistic
pulse acceleration of \cite{liangetal2003}. Unlike previous work, we use the
actual electron to proton mass ratio and focus on understanding trapping vs.
transmission of the ambient plasma by the pulses and on the particle
acceleration spectra. We find that the accelerated electron distribution
internal to the slab develops a double-power law. We predict that emission from
reflected/trapped external electrons will peak after that of the internal
electrons. We also find that the thin discrete pulses trap ambient electrons
but allow protons to pass through, resulting in less drag on the pulse than in
the case of trapping of both species. Poynting flux dominated scenarios have
been proposed as the driver of relativistic outflows and particle acceleration
in the most powerful astrophysical jets.


title:
On the reliability of merger-trees and the mass growth histories of dark
  matter haloes

abstract:
  We have used merger trees realizations to study the formation of dark matter
haloes. The construction of merger-trees is based on three different pictures
about the formation of structures in the Universe. These pictures include: the
spherical collapse (SC), the ellipsoidal collapse (EC) and the non-radial
collapse (NR). The reliability of merger-trees has been examined comparing
their predictions related to the distribution of the number of progenitors, as
well as the distribution of formation times, with the predictions of analytical
relations. The comparison yields a very satisfactory agreement. Subsequently,
>.........


title:
Evolution of the Loop-Top Source of Solar Flares--Heating and Cooling
  Processes

abstract:
  We present a study of the spatial and spectral evolution of the loop-top (LT)
sources in a sample of 6 flares near the solar limb observed by {\it RHESSI}. A
distinct coronal source, which we identify as the LT source, was seen in each
of these flares from the early ``pre-heating'' phase through the late decay
phase. Spectral analyses reveal an evident steep power-law component in the
pre-heating and impulsive phases, suggesting that the particle acceleration
starts upon the onset of the flares. In the late decay phase the LT source has
a thermal spectrum and appears to be confined within a small region near the
top of the flare loop, and does not spread throughout the loop, as is observed
at lower energies. The total energy of this source decreases usually faster
than expected from the radiative cooling but much slower than that due to the
classical Spitzer conductive cooling along the flare loop. These results
indicate the presence of a distinct LT region, where the thermal conductivity
is suppressed significantly and/or there is a continuous energy input. We
suggest that plasma wave turbulence could play important roles in both heating
the plasma and suppressing the conduction during the decay phase of solar
flares. With a simple quasi-steady loop model we show that the energy input in
the gradual phase can be comparable to that in the impulsive phase and
demonstrate how the observed cooling and confinement of the LT source can be
used to constrain the wave-particle interaction.


title: The Shapley super-cluster. New X-ray detections and mass distribution

abstract:
  The largest and the deepest super-structure known today is the Shapley
super-cluster. This is the sky area with the highest over-density of galaxy
clusters and therefore also an ideal region to test the effects of a high
density environment on galaxies and on clusters. We performed an X-ray survey
of a wide region surrounding the Shapley super-structure. Additionally to
previously known super-cluster X-ray members, we identified diffuse X-ray
emission from 35 cluster candidates without previous X-ray detection. 21 of
them were previously known, optically selected super-cluster members, while the
other candidates had not been previously detected in any wavelength range.
Optical follow-up observations revealed that at least four of these new
candidates also have optical cluster counterparts. The super-cluster shows a
slightly flattened and elongated morphology. Clusters outside the central dense
core are preferentially located in four perpendicular filaments in a similar
way to what is seen in simulations of Large Scale Structure. We measure the
cluster number density in the region to be more than one order of magnitude
higher than the mean density of rich Abell clusters previously observed at
similar Galactic latitudes; this over-density, in the super-cluster outskirts,
is mainly due to an excess of low X-ray luminous clusters (with respect to an
average population), which leads us to think that the whole region is still
accreting low luminosity, small objects from the outskirts. Pushing our total
X-ray mass estimate to fainter clusters would drastically increase the total
super-cluster mass measure, because of the presence of the rich X-ray low
luminosity population.


title:
Discovery of Radio Emission from Transient Anomalous X-ray Pulsar XTE
  J1810-197

abstract:
  We report the first detection of radio emission from any anomalous X-ray
pulsar (AXP). Data from the Very Large Array (VLA) MAGPIS survey with angular
resolution 6" reveals a point-source of flux density 4.5 +/- 0.5 mJy at 1.4 GHz
at the precise location of the 5.54 s pulsar XTE J1810-197. This is greater
than upper limits from all other AXPs and from quiescent states of soft
gamma-ray repeaters (SGRs). The detection was made in 2004 January, 1 year
after the discovery of XTE J1810-197 during its only known outburst. Additional
VLA observations both before and after the outburst yield only upper limits
that are comparable to or larger than the single detection, neither supporting
nor ruling out a decaying radio afterglow related to the X-ray turn-on. Another
hypothesis is that, unlike the other AXPs and SGRs, XTE J1810-197 may power a
radio synchrotron nebula by the interaction of its particle wind with a
moderately dense environment that was not evacuated by previous activity from
this least luminous, in X-rays, of the known magnetars.


title:
Fast growth of magnetic fields in galaxy clusters: a self-accelerating
  dynamo

abstract:
  We propose a model of magnetic-field growth in galaxy clusters whereby the
field is amplified by a factor of about 10^8 over a cosmologically short time
of ~10^8 yr. Our model is based on the idea that the viscosity of the
intracluster medium during the field-amplification epoch is determined not by
particle collisions but by plasma microinstabilities: these give rise to
small-scale fluctuations, which scatter particles, increasing their effective
collision rate and, therefore, the effective Reynolds number. This gives rise
to a bootstrap effect as the growth of the field triggers the instabilities
which increase the Reynolds number which, in turn, accelerates the growth of
the field. The growth is explosive and the result is that the observed field
strength is reached over a fraction of the cluster lifetime independent of the
exact strength of the seed field (which only needs to be above ~10^{-15} G to
trigger the explosive growth).


title:
Masses of high-z galaxy hosting haloes from angular clustering and their
  evolution in the CDM model

abstract:
  We examine masses of hosting haloes of two photometrically-selected high-z
galaxy samples: the old passively-evolving galaxies (OPEGs) and Lyman Break
Galaxies (LBGs) both taken from the Subaru/XMM-Newton Deep Survey (SXDS). The
large survey area of the SXDS (1sq deg) allows us to measure the angular
two-point correlation functions to a wide separation of >10 arcmin with a good
statistical quality. We utilize the halo model prescription for estimating
characteristic masses of hosting haloes from the measured large-scale
clustering amplitudes. It is found that the hosting halo mass positively
correlates with the luminosity of galaxies. Then, adopting the extended
Press-Schechter model (EPS), we compute the predictions for the mass evolution
of the hosting haloes in the framework of the cold dark matter (CDM) cosmology
in order to make an evolutionary link between the two galaxy samples at
different redshifts and to identify their present-day descendants by letting
their haloes evolve forward in time. It is found that, in the view of the mass
evolution of hosting haloes in the CDM model, bright LBGs are consistent with
being the progenitor of the OPEGs, whereas it is less likely that the LBG
population, as a whole, have evolved into the OPEG population. It is also found
that the present-day descendants of both the bright LBGs and OPEGs are likely
to be located in massive systems such as groups of galaxies or clusters of
galaxies. Finally, we estimate the hosting halo mass of local early-type galaxy
samples from the 2dF and SDSS based on the halo model and it turns out that
their expected characteristic mass of hosting haloes is in good agreement with
the EPS predictions for the descendant's mass of both the bright LBGs and
OPEGs.


title:
Characteristics of the curvature effect of uniform jets or spherical
  fireballs

abstract:
  Qin et al. (2004) have derived a formula of count rates based on a model of
highly symmetric expanding fireballs, where the Doppler effect is the key
factor to be concerned. In this paper, we employ the formula to both the Qin
model and the uniform jet model to study how the rising timescale,
$\Delta\tau_{\theta,r}$, and the decay timescale, $\Delta\tau_{\theta,d}$, of a
local pulse affect the light curve of GRBs. Our analysis shows that they do
make contributions to both rising and decay portions of the light curve of
GRBs. Associated with a local pulse with both rising and decay portions, the
light curve of GRBs in the rising portion is expected to undergo a concave
phase and then a convex one, which we call a "concave-to-convex" character,
whereas that in the decay portion is expected to evolve an opposite process
which is called a "convex-to-concave" character, regardless of being in Qin
model or in the uniform jet model. These characteristics are independent of
local pulse shapes and their rest frame radiation forms. The diversity of light
curves are caused by different forms of local pulses and different ratios of
$\Delta\tau_{\theta,r}$ to $\Delta\tau_{\theta,d}$. We study a sample of 86 GRB
pulses detected by the BATSE instrument on board the Compton Gamma Ray
Observatory and find that the "concave-to-convex" (expected in the rising
portion of the light curve) and "convex-to-concave" (expected in the decay
portion) characters, which result from the curvature effect of spherical
surface (or the Doppler effect), do exist in the light curve of some GRBs.


title:
Constraints on radiatively inefficient accretion history of active
  galactic nuclei from hard cosmological X-ray background

abstract:
  The transition of a standard thin disk to a radiatively inefficient accretion
flow (RIAF) is expected to occur, when its dimensionless accretion rate is
lower than the critical value. The RIAF is very hot, and it radiates mostly in
the hard X-ray band (>100 keV). Assuming that the accretion disk in every
bright active galactic nucleus (AGN) will finally undergo a RIAF phase while
the accretion rate is lower than the critical value, we calculate the
contribution of the RIAFs in AGNs to the cosmological X-ray background of
10-1000 keV. We find that the timescale of the RIAF accreting at slightly below
the critical rate should be shorter than 0.01 of the bright AGN lifetime if the
critical accretion rate is 0.01, i.e., the accretion rate declines from the
critical value to a rate significantly lower than this critical rate within
this RIAF timescale. The derived RIAF timescale is affected by the parameters
adopted in the model calculations, which is also discussed in this Letter.


title: North-South Distribution of Solar Flares during Cycle 23

abstract:
  In this paper, we investigate the spatial distribution of solar flares in the
northern and southern hemisphere of the Sun that occurred during the period
1996 to 2003. This period of investigation includes the ascending phase, the
maximum and part of descending phase of solar cycle 23. It is revealed that the
flare activity during this cycle is low compared to previous solar cycle,
indicating the violation of Gnevyshev-Ohl rule. The distribution of flares with
respect to heliographic latitudes shows a significant asymmetry between
northern and southern hemisphere which is maximum during the minimum phase of
the solar cycle. The present study indicates that the activity dominates the
northern hemisphere in general during the rising phase of the cycle
(1997-2000). The dominance of northern hemisphere is shifted towards the
southern hemisphere after the solar maximum in 2000 and remained there in the
successive years. Although the annual variations in the asymmetry time series
during cycle 23 are quite different from cycle 22, they are comparable to cycle
21.


title:
The Axis-Ratio Distribution of Galaxy Clusters in the SDSS-C4 Catalog as
  a New Cosmological Probe

abstract:
  We analyze the C4 catalog of galaxy clusters from the Sloan Digital Sky
Survey (SDSS) to investigate the axis-ratio distribution of the projected two
dimensional cluster profiles. We consider only those objects in the catalog
whose virial mass is close to 10^{14}h^{-1}M_{sun}, with member galaxies within
the scale radius 1000 kpc. The total number of such objects turns out to be
336. We also derive a theoretical distribution by incorporating the effect of
projection onto the sky into the analytic formalism proposed recently by Lee,
Jing, & Suto. The theoretical distribution of the cluster axis-ratios is shown
to depend on the amplitude of the linear power spectrum (sigma_8) as well as
the density parameter (Omega_{m}). Finally, fitting the observational data to
the analytic distribution with Omega_{m} and sigma_{8} as two adjustable free
parameters, we find the best-fitting value of sigma_{8}=(1.01 +/-
0.09)(Omega_{m}/0.6)^{(0.07 +/- 0.02) +0.1 Omega_{m}}$. It is a new
sigma_{8}-Omega_{m} relation, different from the previous one derived from the
local abundance of X-ray clusters. We expect that the axis-ratio distribution
of galaxy clusters, if combined with the local abundance of clusters, may put
simultaneous constraints on sigma_{8} and Omega_{m}.


title: Spectro-photometric study of the GRB 030329 host galaxy

abstract:
  In this study optical/near-infrared(NIR) broad band photometry and optical
spectroscopic observations of the GRB 030329 host galaxy are presented. The
Spectral Energy Distribution (SED) of the host is consistent with a starburst
galaxy template with a dominant stellar population age of ~150 Myr and an
extinction Av ~0.6. Analysis of the spectral emission lines shows that the host
is likely a low metallicity galaxy. Two independent diagnostics, based on the
restframe UV continuum and the [OII] line flux, provide a consistent
unextincted star formation rate of SFR ~0.6 Mo yr^-1. The low absolute
magnitude of the host (M_B ~ -16.5) implies a high specific star formation rate
value, SSFR = ~34 Mo yr^-1 (L/L*)^-1.


title: Reconstruction of general scalar-field dark energy models

abstract:
  The reconstruction of scalar-field dark energy models is studied for a
general Lagrangian density $p(\phi, X)$, where $X$ is a kinematic term of a
scalar field $\phi$. We implement the coupling $Q$ between dark energy and dark
matter and express reconstruction equations using two observables: the Hubble
parameter $H$ and the matter density perturbation $\delta_m$. This allows us to
determine the structure of corresponding theoretical Lagrangian together with
the coupling $Q$ from observations. We apply our formula to several forms of
Lagrangian and present concrete examples of reconstruction by using the recent
Gold dataset of supernovae measurements. This analysis includes a generalized
ghost condensate model as a way to cross a cosmological-constant boundary even
for a single-field case.


title:
Observation of VHE gamma-ray emission from the Active Galactic Nucleus
  1ES1959+650 using the MAGIC telecope

abstract:
  The MAGIC Cherenkov telescope has observed very high energy (VHE) gamma-ray
emission from the Active Galactic Nucleus 1ES1959+650 during six hours in
September and October 2004. The observations were carried out alternated with
the Crab Nebula, whose data were used as reference source for optimizing
gamma/hadron separation and for flux comparison. The data analysis shows VHE
gamma-ray emission of 1ES1959+650 with ~ 8 sigma significance, at a time of low
activity in both optical and X-ray wavelengths. An integral flux above ~ 180
GeV of about 20% of the Crab was obtained. The light curve, sampled over 7
days, shows no significant variations. The differential energy spectrum between
180 GeV and 2 TeV can be fitted with a power law of index -2.72 +/- 0.14. The
spectrum is consistent with the slightly steeper spectrum seen by HEGRA at
higher energies, also during periods of low X-ray activity.


title: Magnetized CMB anisotropies

abstract:
  Possible effects of large-scale magnetic fields on the Cosmic Microwave
Background (CMB) are reviewed. Depending on the specific branch of the spectrum
of plasma excitations, magnetic fields are treated either within a two-fluid
plasma description or within an effective (one-fluid) approach. The uniform
field approximation is contrasted with the fully inhomogeneous field
approximation. It is argued that the interplay between CMB physics and
large-scale magnetic fields will represent a rather interesting
cross-disciplinary arena along the next few years.


title: Stellar evolution before the ZAMS

abstract:
  Young stars on their way to the ZAMS evolve in significantly different ways
depending on mass. While the theoretical and observational properties of low-
and intermediate-mass stars are rather well understood and/or empirically
tested, the situation for massive stars (>10-15 Msun) is, to say the least,
still elusive. On theoretical grounds, the PMS evolution of these objects
should be extremely short, or nonexistent at all. Observationally, despite a
great deal of effort, the simple (or bold) predictions of simplified models of
massive star formation/evolution have proved more difficult to be checked.
After a brief review of the theoretical expectations, I will highlight some
critical test on young stars of various masses.


title: Cascades of shocks in Active Galactic Nuclei and their radiation

abstract:
  We discuss accretion flows on massive black holes in which different elements
of the flow (clumps) have velocities that may differ substantially. We estimate
the consequence of collisions between these clumps as they come close to the
central object and calculate the resulting radiation. We show that this
radiation is similar to that observed in the optical to X-ray spectral domain
in Seyfert galaxies and quasars. We also show that the large scale accretion is
likely to be clumpy when arriving in the active region and that the clumps keep
their identity between collisions.