title:
Second-order gravitational effects of local inhomogeneities on CMB
  anisotropies and non-Gaussian signatures

abstract:
  Based on the second-order nonlinear theory of perturbations in non-zero
\Lambda flat cosmological models, we study the gravitational effects of local
inhomogeneities on cosmic microwave background (CMB) anisotropies. As the local
inhomogeneities we consider firstly large-scale dipole and quadruple
distributions of galaxies around us and next an isolated cluster-scale matter
distribution. It is found that, due to the second-order integral Sachs-Wolfe
effect, the north-south asymmetry of CMB anisotropies and non-Gaussian
signatures (in terms of scale-dependent estimators of kurtosis) in a spot-like
object are caused from these matter distributions along light paths. Our
theoretical results seem to be consistent with recent various observational
results which have been shown by Hansen et al., Eriksen et al., Vielva et al.
and Cruz et al.


title: A Primer to Relativistic MOND Theory

abstract:
  We first review the nonrelativistic lagrangian theory as a framework for the
MOND equation. Obstructions to a relativistic version of it are discussed
leading up to TeVeS, a relativistic tensor-vector-scalar field theory which
displays both MOND and Newtonian limits. The whys for its particular structure
are discussed and its achievements so far are summarized.


title:
Three Spectral States of the Disk X-Ray Emission of the Black-Hole
  Candidate 4U 1630-47

abstract:
  We studied a time history of X-ray spectral states of a black-hole candidate,
4U 1630-47, utilizing data from a number of monitoring observations with the
Rossi X-Ray Timing Explorer over 1996--2004. These observations covered five
outbursts of 4U 1630-47, and most of the data recorded typical features of the
high/soft states. We found that the spectra in the high/soft states can be
further classified into three states. The first spectral state is explained by
a concept of the standard accretion disk picture. The second state appears in
the so-called very high state, where a dominant hard component is seen and the
disk radius apparently becomes too small. These phenomena are explained by the
effect of inverse Compton scattering of disk photons, as shown by Kubota,
Makishima, & Ebisawa (2001, ApJ, 560, L147) for GRO J1655-40. The third state
is characterized in such a way that the disk luminosity varies in proportion to
$T_{\rm in}^2$, rather than $T_{\rm in}^4$, where $T_{\rm in}$ is the
inner-disk temperature. This state is suggested to be an optically-thick and
advection-dominated slim disk, as suggested by Kubota & Makishima (2004, ApJ,
601, 428) for XTE J1550-564. The second and third states appear, with good
reproducibility, when $T_{\rm in}$ and the total X-ray luminosity are higher
than 1.2 keV and $\sim2.5\times10^{38}(D/10\quad{\rm kpc})^2\l
eft[\cos{\theta}/(1/\sqrt{3})]^{-1}$ erg s$^{-1}$, respectively, where $D$ is
the distance to the object and $\theta$ is the inclination angle to the disk.
The present results suggest that these three spectral states commonly appear
among black-hole binaries under high accretion rates.


title:
Scaling Mass Profiles around Elliptical Galaxies Observed with Chandra
  and XMM-Newton

abstract:
  We investigated the dynamical structure of 53 elliptical galaxies, based on
the {\it Chandra} archival X-ray data. In X-ray luminous galaxies, a
temperature increases with radius and a gas density is systematically higher at
the optical outskirts, indicating a presence of a significant amount of the
group-scale hot gas. In contrast, X-ray dim galaxies show a flat or declining
temperature profile against radius and the gas density is relatively lower at
the optical outskirts. Thus it is found that X-ray bright and faint elliptical
galaxies are clearly distinguished by the temperature and gas density profile.
The mass profile is well scaled by a virial radius $r_{200}$ rather than an
optical-half radius $r_e$, and is quite similar at $(0.001-0.03)r_{200}$
between X-ray luminous and dim galaxies, and smoothly connects to those of
clusters of galaxies. At the inner region of $(0.001-0.01)r_{200}$ or
$(0.1-1)r_e$, the mass profile well traces a stellar mass with a constant
mass-to-light ratio of $M/L_{\rm B}=3-10(M_{\odot}/L_{\odot})$. $M/L_{\rm B}$
ratio of X-ray bright galaxies rises up steeply beyond $0.01r_{200}$, and thus
requires a presence of massive dark matter halo. From the deprojection analysis
combined with the {\it XMM-Newton} data, we found that X-ray dim galaxies, NGC
3923, NGC 720, and IC 1459, also have a high $M/L_{\rm B}$ ratio of 20--30 at
20 kpc, comparable to that of X-ray luminous galaxies. Therefore, dark matter
is indicated to be common in elliptical galaxies, and their distribution almost
follows the NFW profile, as well as galaxy clusters.


title: On the structure of globular cluster systems in elliptical galaxies

abstract:
  It has long been known that the radial density profiles of globular cluster
systems (GCSs) in elliptical galaxies vary with the total luminosities of their
host galaxies. In order to elucidate the origin of this structural non-homology
in GCSs, we numerically investigate the structural properties of GCSs in
elliptical galaxies formed from a sequence of major dissipationless galaxy
merging. We find that the radial density profiles of GCSs in elliptical
galaxies become progressively flatter as the galaxies experience more major
merger events. The density profiles of GCSs in ellipticals are well described
as power-laws with slopes (${\alpha}_{\rm gc}$) ranging from -2.0 to -1.0. They
are flatter than, and linearly proportional to, the slopes (${\alpha}_{\rm s}$)
of the stellar density profiles of their host galaxies. We also find that the
GCS core radii ($r_{\rm c}$) of the density profiles are larger in ellipticals
that experienced more mergers. By applying a reasonable scaling relation
between luminosities and sizes of galaxies to the simulation results, we show
that ${\alpha}_{\rm gc} \approx -0.36 M_{\rm V}-9.2$, $r_{\rm c} \approx -1.85
M_{\rm V}$, and ${\alpha}_{\rm gc} \approx 0.93 {\alpha}_{\rm s}$, where
$M_{\rm V}$ is the total $V$-band absolute magnitude of a galaxy.


title:
High-amplitude Delta Scuti stars in the Galactic bulge from the OGLE-II
  and MACHO data

abstract:
  Searching for main-sequence pulsators, we analyzed photometry of ~200,000
variable star candidates from the OGLE-II Galactic fields, finding 193
high-amplitude Delta Scuti stars. This doubles the number of known stars of
this type. The MACHO data, available for half of stars, were also analyzed. In
our sample of the HADS stars, we found 50 multiperiodic objects, including 39
that have period ratios in the range of 0.76-0.80, an indication of the radial
fundamental and first-overtone pulsation. We discuss the resulting Petersen
diagram for these stars in view of the period ratios predicted by models.
Except for stars showing pulsations in the radial fundamental mode and first
overtone, we find the evidence for higher radial overtones and non-radial modes
in the analyzed sample of multiperiodic HADS stars.


title:
Is the cluster of galaxies "Abell 194" surrounded by an Einstein-Straus
  vacuole?

abstract:
  It is suggested that an ``Einstein-Straus vacuole'' -- a region of space time
with a metric obtained by solving the equations of general relativity of a mass
condensation in an expanding universe with vanishing cosmological constant --
surrounds the cluster of galaxies ``Abell 194''. This hypothesis is shown to
predict a distribution of galaxy redshifts that is in better accord with
observations than the one expected in the cosmological concordance model.


title: Hard Spectra of X-Ray Pulsars from INTEGRAL Data

abstract:
  We present spectra for 34 accretion-powered X-ray and one millisecond pulsars
that were within the field of view of the INTEGRAL observatory over two years
(December 2002 - January 2005) of its in-orbit operation and that were detected
by its instruments at a statistically significant level (> 8 sigma in the
energy range 18--60 keV). There are seven recently discovered objects of this
class among the pulsars studied: 2RXP J130159.6-635806, IGR/AX J16320-4751, IGR
J16358-4726, AX J163904-4642, IGR J16465-4507, SAX/IGR J18027-2017 and AX
J1841.0-0535. We have also obtained hard X-ray (> 20 keV) spectra for the
accretion-powered pulsars A 0114+650, RX J0146.9+6121, AX J1820.5-1434, AX
J1841.0-0535 and the millisecond pulsar XTE J1807-294 for the first time. We
analyze the evolution of spectral parameters as a function of the intensity of
the sources and compare these with the results of previous studies.


title: GOODS, UDF, and the evolution of early-type galaxies

abstract:
  The HST/ACS images of GOODS-South have been used to select a sample of
early-type galaxies, based on morphology and on the Kormendy relation. The
classification scheme does not use galaxy colours, hence it does not bias
against young stellar populations. The 249 galaxies (i_AB<24) paint a complex
formation picture. Their stellar populations show gradients which readily rule
out a large range of ages among and within galaxies. On the other hand, there
is a decrease in the comoving number density, which suggests a strong bias when
comparing local and distant early-type galaxies. This bias can be caused either
by a significant fraction of non early-type progenitors or by a selection
effect (e.g. dust-enshrouded progenitors). The deep images of the UDF were used
to determine the structural properties of some of these galaxies. Regarding the
distribution of disky/boxy isophotes, we do not find large differences with
respect to local systems. However, some early-types with the standard features
of a red and dead galaxy reveal interesting residuals, possible signatures of
past merging events.


title: Solar Neutron Events of October-November 2003

abstract:
  During the period when the Sun was intensely active on October-November 2003,
two remarkable solar neutron events were observed by the ground-based neutron
monitors. On October 28, 2003, in association with an X17.2 large flare, solar
neutrons were detected with high statistical significance (6.4 sigma) by the
neutron monitor at Tsumeb, Namibia. On November 4, 2003, in association with an
X28 class flare, relativistic solar neutrons were observed by the neutron
monitors at Haleakala in Hawaii and Mexico City, and by the solar neutron
telescope at Mauna Kea in Hawaii simultaneously. Clear excesses were observed
at the same time by these detectors, with the significance calculated as 7.5
sigma for Haleakala, and 5.2 sigma for Mexico City. The detector onboard the
INTEGRAL satellite observed a high flux of hard X-rays and gamma-rays at the
same time in these events. By using the time profiles of the gamma-ray lines,
we can explain the time profile of the neutron monitor. It appears that
neutrons were produced at the same time as the gamma-ray emission.


title: VSOP monitoring of the compact BL Lac object AO 0235+164

abstract:
  In 1999, the highly compact and variable BL Lac object AO 0235+164 was
identified as the highest brightness temperature active galactic nucleus
observed with the VLBI Space Observatory Programme (VSOP), with T_B > 5.8 x
10^{13} K. The sub-milliarcsecond radio structure of this source has been
studied with dual-frequency (1.6 and 5 GHz), polarization-sensitive VSOP
observations during 2001 and 2002. Here we present the results of this
monitoring campaign. At the time of these observations, the source was weakly
polarized and characterized by a radio core that is clearly resolved on
space-ground baselines.


title: The orbital period of Nova V2540 Ophiuchi (2002)

abstract:
  We present the results of 26 nights of CCD photometry of the nova V2540 Oph
(2002) from 2003 and 2004. We find a period of 0.284781 +/- 0.000006 d (6.8347
+/- 0.0001 h) in the data. Since this period was present in the light curves
taken in both years, with no apparent change in its value or amplitude, we
interpret it as the orbital period of the nova binary system. The mass-period
relation for cataclysmic variables yields a secondary mass of about 0.75 +/-
0.04 Msun. From maximum magnitude - rate of decline relation, we estimate a
maximum absolute visual magnitude of M(V)=-6.2 +/- 0.4 mag. This value leads to
an uncorrected distance modulus of (m-M) = 14.7 +/- 0.7. By using the
interstellar reddening for the location of V2540 Oph, we find a rough estimate
for the distance of 5.2 +/- 0.8 kpc. We propose that V2540 Oph is either: 1) a
high inclination cataclysmic variable showing a reflection effect of the
secondary star, or having a spiral structure in the accretion disc, 2) a high
inclination intermediate polar system, or less likely 3) a polar.


title: Low frequency radio monitoring of Cygnus X-1 and Cygnus X-3

abstract:
  We present results of monitoring observations of the micro-quasars CygnusX-1
and Cygnus X-3 at 0.61 and 1.28 GHz. The observations were performed with Giant
Meter-wave Radio Telescope, GMRT, between 2003 June and 2005 January. Variable,
unresolved sources were found in both cases. Cyg X-1 was detected in about half
of the observations, with a median flux density about 7 mJy at each frequency.
The results show clearly that there is a break in the spectrum above 1.28 GHz.
The variations in Cyg X-1 may be due to refractive interstellar scintillation.
Cyg X-3 was detected in each observation, and varied by a factor of 4. For this
source, models of the scintillation suggest a very long timescale (of the order
of 40 yr at 1.28 GHz), and therefore we believe that the variations are
intrinsic to the source.


title:
Constraints on holographic dark energy from X-ray gas mass fraction of
  galaxy clusters

abstract:
  We use the Chandra measurements of the X-ray gas mass fraction of 26 rich
clusters released by Allen et al. to perform constraints on the holographic
dark energy model. The constraints are consistent with those from other
cosmological tests, especially with the results of a joint analysis of
supernovae, cosmic microwave background, and large scale structure data. From
this test, the holographic dark energy also tends to behave as a quintom-type
dark energy.


title: MOND and Cosmology

abstract:
  I review various ideas on MOND cosmology and structure formation beginning
with non-relativistic models in analogy with Newtonian cosmology. I discuss
relativistic MOND cosmology in the context of Bekenstein's theory and propose
an alternative biscalar effective theory of MOND in which the acceleration
parameter is identified with the cosmic time derivative of a matter coupling
scalar field. Cosmic CDM appears in this theory as scalar field oscillations of
the auxiliary "coupling strength" field.


title: XMM-Newton reveals ~100 new LMXBs in M31 from variability studies

abstract:
  We have conducted a survey of X-ray sources in XMM-Newton observations of
M31, examining their power density spectra (PDS) and spectral energy
distributions (SEDs). Our automated source detection yielded 535 good X-ray
sources; to date, we have studied 225 of them. In particular, we examined the
PDS because low mass X-ray binaries (LMXBs) exhibit two distinctive types of
PDS. At low accretion rates, the PDS is characterised by a broken power law,
with the spectral index changing from ~0 to ~1 at some frequency in the range
\~0.01--1 Hz; we refer to such PDS as Type A. At higher accretion rates, the
PDS is described by a simple power law; we call these PDS Type B. Of the 225
sources studied to date, 75 exhibit Type A variability, and are almost
certainly LMXBs, while 6 show Type B but not Type A, and are likely LMXBs. Of
these 81 candidate LMXBs, 71 are newly identified in this survey; furthermore,
they are mostly found near the centre of M31. Furthermore, most of the X-ray
population in the disc are associated with the spiral arms, making them likely
high mass X-ray binaries (HMXBs). In general these HMXBs do not exhibit Type A
variability, while many central X-ray sources (LMXBs) in the same luminosity
range do. Hence the PDS may distinguish between LMXBs and HMXBs in this
luminosity range.


title: Internal kinematics of isolated modelled disk galaxies

abstract:
  We present a systematic investigation of rotation curves (RCs) of fully
hydrodynamically simulated galaxies, including cooling, star formation with
associated feedback and galactic winds. Applying two commonly used fitting
formulae to characterize the RCs, we investigate systematic effects on the
shape of RCs both by observational constraints and internal properties of the
galaxies. We mainly focus on effects that occur in measurements of intermediate
and high redshift galaxies. We find that RC parameters are affected by the
observational setup, like slit misalignment or the spatial resolution and also
depend on the evolution of a galaxy. Therefore, a direct comparison of
quantities derived from measured RCs with predictions of semi-analytic models
is difficult. The virial velocity V_c, which is usually calculated and used by
semi-analytic models can differ significantly from fit parameters like V_max or
V_opt inferred from RCs. We find that V_c is usually lower than typical
characteristic velocities derived from RCs. V_max alone is in general not a
robust estimator for the virial mass.


title: Teff and log g Determinations

abstract:
  A discussion on the determination of effective temperature (Teff) and surface
gravity (log g) is presented. The observational requirements for
model-independent fundamental parameters are summarized, including an
assessment of the accuracy of these values for the Sun and Vega. The use of
various model-dependent techniques for determining Teff and log g are outlined,
including photometry, flux fitting, and spectral line ratios. A combination of
several of these techniques allows for the assessment of the quality of our
parameter determinations. While some techniques can give precise parameter
determinations, the overall accuracy of the values is significantly less and
sometimes difficult to quantify.


title: Different convection models in ATLAS

abstract:
  Convection is an important phenomenon in the atmospheres of A-type and cooler
stars. A description of convection in ATLAS models is presented, together with
details of how it is specified in model calculations. The effects of changing
the treatment of convection on model structures and how this affects observable
quantities are discussed. The role of microturbulence is examined, and its link
to velocity fields within the atmosphere. Far from being free parameters,
mixing-length and microturbulence should be constrained in model calculations.


title: Synthesis of the Beryllium 3131A Spectral Region

abstract:
  The Beryllium spectral region of the Sun, Procyon and 4 stars in the open
cluster NGC6633 up to Teff = 7500K have been synthesised using ATLAS9 model
atmospheres and the MOOG spectral synthesis program.
  The line list used for these syntheses has been modified from the ATLAS9 line
list to improve the quality of the fits in light of the improved opacities in
the new version of the MOOG code.
  Significant changes have been made to the Mn I line at ATLAS9 wavelength
3131.037A and an OH line has been added at 3131.358A. In addition there are a
number of minor changes to gf-values throughout the synthesised region thus
improving the fit for the spectra across the temperature range considerably.


title:
Neutron Star Equation of State and the Possibility of Complex
  Self-Energy in Landau Theory of Fermi Liquid in Presence of Strong Quantizing
  Magnetic Field

abstract:
  Using a relativistic version of Landau theory of Fermi liquid with
$\sigma-\omega$ and $\rho$ mesons exchange, we have obtained an equation of
state for dense neutron star matter in presence of strong quantizing magnetic
field. It is found that in this scenario the self energies of both neutron and
proton components of dense neutron star matter become complex under certain
physical conditions. To be more specific, it is observed that in the exchange
diagrams of $\sigma$, $\omega$ and neutral $\rho$ transfer processes and in the
direct interaction diagram with $\rho_\pm$ transfer reactions, the nucleon
self-energies become complex in nature.


title:
Tracing baryons in the warm-hot intergalactic medium with broad Ly alpha
  absorption

abstract:
  We discuss physical properties and baryonic content of broad Ly alpha
absorbers (BLAs) at low redshift. These absorption systems, recently discovered
in high-resolution, high-signal to noise quasar absorption line spectra,
possibly trace the warm-hot intergalactic medium (WHIM) in the temperature
range between 10^5 and 10^6 K. To extend previous BLA measurements we have
analyzed STIS data of the two quasars H 1821+643 and PG 0953+415 and have
identified 13 BLA candidates along a total (unblocked) redshift path of
dz=0.440. Combining our measurements with previous results for the lines of
sight toward PG 1259+593 and PG 1116+215, the resulting new BLA sample consists
of 20 reliably detected systems as well as 29 additional tentative cases,
implying a BLA number density of dN/dz=22-53. We estimate that the contribution
of BLAs to the baryon density at z=0 is Omega_b(BLA)>0.0027 h_70^-1 for
absorbers with log (N/b)>11.3. This number indicates that WHIM broad Ly alpha
absorbers contain a substantial fraction of the baryons in the local Universe.
(Abridged abstract)


title: An H-band survey of the Herschel Deep Field

abstract:
  We present H-band infra-red galaxy data to a 3 sigma limit of H=22.9 and
optical-infra-red colours of galaxies on the William Herschel Deep Field. These
data were taken from a 7'x 7' area observed for 14 hours with the Omega Prime
camera on the 3.5-m Calar Alto telescope. We derive H-band number counts,
colour-magnitude diagrams and colour histograms. We review our Pure Luminosity
Evolution galaxy count models based on the spectral synthesis models of Bruzual
& Charlot. These PLE models give an excellent fit to the our H band count data
to H<22.5 and HDF count data to H<28. However, PLE models with a Salpeter IMF
for early-type galaxies overestimate the average galaxy redshift in K<20 galaxy
redshift surveys. Models that assume a steep x=3 IMF give better agreement
data, although they do show an unobserved peak in B-H and I-H colour
distributions at faint H magnitudes corresponding to z>1 early-type galaxies.
This feature may simply reflect a larger scatter in optical-infra-red colours
than in the B-R colour of early-type galaxies at this redshift. This scatter is
obvious in optical-IR colour-colour diagrams and may be explained by on-going
star-formation in an intermediate sub-population of early-type galaxies. The
numbers of EROs detected are a factor of 2-3 lower than predicted by the
early-type models that assume the Salpeter IMF and in better agreement with
those that assume the x=3 IMF. The tight sequence of early-type galaxies also
shows a sub-class which is simultaneously redder in infrared bands and bluer in
the bluer bands than the classical, passive early-type galaxy; this sub-class
appears at relatively low redshifts and may constitute an intermediate age,
early-type population.


title:
On the relevance of subcritical hydrodynamic turbulence to accretion
  disk transport

abstract:
  Hydrodynamic unstratified keplerian flows are known to be linearly stable at
all Reynolds numbers, but may nevertheless become turbulent through nonlinear
mechanisms. However, in the last ten years, conflicting points of view have
appeared on this issue. We have revisited the problem through numerical
simulations in the shearing sheet limit. It turns out that the effect of the
Coriolis force in stabilizing the flow depends on whether the flow is cyclonic
(cooperating shear and rotation vorticities) or anticyclonic (competing shear
and rotation vorticities); keplerian flows are anticyclonic. We have obtained
the following results: i/ The Coriolis force does not quench turbulence in
subcritical flows; ii/ The resolution demand, when moving away from the
marginal stability boundary, is much more severe for anticyclonic flows than
for cyclonic ones. Presently available computer resources do not allow
numerical codes to reach the keplerian regime. iii/ The efficiency of turbulent
transport is directly correlated to the Reynolds number of transition to
turbulence $Rg$, in such a way that the Shakura-Sunyaev parameter $\alpha\sim
1/Rg$. iv/ Even the most optimistic extrapolations of our numerical data show
that subcritical turbulent transport would be too inefficient in keplerian
flows by several orders of magnitude for astrophysical purposes. v/ Our results
suggest that the data obtained for keplerian-like flows in a Taylor-Couette
settings are largely affected by secondary flows, such as Ekman circulation.


title:
The massive binary CPD-41degr7742 II. Optical light curve and X-ray
  observations

abstract:
  In the first paper of this series, we presented a detailed high-resolution
spectroscopic study of CPD - 41degr7742, deriving for the first time an orbital
solution for both components of the system. In this second paper, we focus on
the analysis of the optical light curve and on recent XMM-Newton X-ray
observations. In the optical, the system presents two eclipses, yielding an
inclination i ~ 77degr. Combining the constraints from the photometry with the
results of our previous work, we derive the absolute parameters of the system.
We confirm that the two components of CPD - 41degr7742 are main sequence stars
(O9 V + B1-1.5 V) with masses (M_1 ~ 18 Msol and M_2 ~ 10 Msol) and respective
radii (R_1 ~ 7.5 Rsol and R_2 ~ 5.4 Rsol) close to the typical values expected
for such stars. We also report an unprecedented set of X-ray observations that
almost uniformly cover the 2.44-day orbital cycle. The X-ray emission from CPD
- 41degr7742 is well described by a two-temperature thermal plasma model with
energies close to 0.6 and 1.0 keV, thus slightly harder than typical early-type
emission. The X-ray light curve shows clear signs of variability. The emission
level is higher when the primary is in front of the secondary. During the high
emission state, the system shows a drop of its X-ray emission that almost
exactly matches the optical eclipse. We interpret the main features of the
X-ray light curve as the signature of a wind-photosphere interaction, in which
the overwhelming primary O9 star wind crashes into the secondary surface.
Alternatively the light curve could result from a wind-wind interaction zone
located near the secondary star surface. As a support to our interpretation, we
provide a phenomenological geometric model that qualitatively reproduces the
observed modulations of the X-ray emission.


title: BASTI: An interactive database of updated stellar evolution models

abstract:
  We present a new database of stellar evolution models for a large range of
masses and chemical compositions, based on an up-to-date theoretical framework.
We briefly discuss the physical inputs and the assumptions adopted in computing
the stellar models. We explain how to access to the on-line archive and briefly
discuss the interactive WEB tools that can be used to compute user-specified
evolutionary tracks/isochrones/luminosity functions. The future developments of
this database are also outlined.


title: A Far Ultraviolet Study of the Old Nova V841 Oph

abstract:
  We have carried out a synthetic spectral analysis of archival IUE spectra of
the old nova V841 Oph (Nova Oph 1848) taken 15 years apart. The spectra reveal
a rising continuum shortward of 1560\AA, a C {\sc iv} P-Cygni profile
indicative of wind outflow associated with disk accretion in one spectrum, a
deep Ly $\alpha$ profile, and strong N {\sc v} (1238\AA, 1242\AA) and O {\sc v}
(1371\AA) wind/coronal absorption lines. Numerous sharp interstellar resonance
lines are also present. A grid of high gravity atmospheres and accretion disk
models, spanning a wide range of inclinations, accretion rates and white dwarf
masses was compared to the de-reddened spectra. We find that, for a steady
state accretion disk model to account for the FUV spectra, the accretion rate
is only $\sim$3 $\times$ 10$^{-11}$ M$_{\sun}$/yr, 147 years after its outburst
in 1848, with an implied distance within $\sim$300 pc. The accretion rate at
147 years post-outburst is smaller than expected for an old nova.


title:
Observational determination of the time delays in gravitational lens
  system Q2237+030

abstract:
  We present new brightness monitoring observations of the 4 components of
gravitationally lensed system Q2237+0305, which show detection of an intrinsic
quasar brightness fluctuation at a time of subdued microlensing activity,
between June 27 and October 12, 2003. These data were used to determine the
time delays between the arrivals of the four images. The measured delays are
-6, 35, and 2 hours for images B, C and D relative to A, respectively, so they
confirm that the long history of brightness monitoring has produced significant
detection of microlensing. However the error bars associated with the delays,
of order 2 days, are too large to discriminate between competing macro-imaging
models. Moreover, our simulations show that for the amplitude of this intrinsic
fluctuation and for photometric errors intrinsic to optical monitoring from our
1.5-m telescope or from the OGLE monitoring, a daily sampled brightness record
cannot produce reliable lags for model discrimination. We use our simulations
to devise a strategy for future delay determination with optical data.
Nevertheless, we regard these first estimates to be significant, since they are
the first direct measurements of time delays made for this system from
ground-based observations in the visual wavelengths. Our results provide the
most convincing confirmation of the gravitational-lens nature of Q2237+0305,
and give observational justification to the extensive literature which
attributes the quasar's previously observed brightness fluctuations to
microlensing.


title:
A Search for High-energy Muon Neutrinos from the Galactic Plane with
  AMANDA-II

abstract:
  Interactions of cosmic rays with the galactic interstellar medium produce
high-energy neutrinos through the decay of charged pions and kaons. We report
on a search with the AMANDA-II detector for muon neutrinos from the region of
the galactic plane below the horizon from the South Pole (33 degrees < galactic
longitude < 213 degrees). Data from 2000 to 2003 were used for the search,
representing a total of 807 days of livetime and 3329 candidate muon neutrino
events. No excess of events was observed. For a spectrum of E^{-2.7} and
Gaussian spatial distribution (sigma = 2.1 degrees) around the galactic
equator, we calculate a flux limit of 4.8 x 10^{-4} GeV^{-1} cm^{-2} s^{-1}
sr^{-1} in the energy range from 0.2 to 40 TeV.


title: The Chaplygin dark star

abstract:
  We study the general properties of a spherically symmetric body described
through the generalized Chaplygin equation of state. We conclude that such
object, dubbed generalized Chaplygin dark star, should exist within the context
of the generalized Chaplygin gas model of unification of dark energy and dark
matter, and derive expressions for its size and expansion velocity. A criteria
for the survival of the perturbations in the GCG background that give origin to
the dark star are developed, and its main features are analyzed.


title: Designing Weak Lensing Surveys: A Generalised Eigenmode Analysis

abstract:
  We study the estimators of various second-order weak lensing statistics such
as the shear correlation functions xi_\pm and the aperture mass dispersion
<M_ap^2> which can directly be constructed from weak lensing shear maps. We
compare the efficiency with which these estimators can be used to constrain
cosmological parameters. To this end we introduce the Karhunen-Loeve (KL)
eigenmode analysis techniques for weak lensing surveys. These tools are shown
to be very effective as a diagnostics for optimising survey strategies. The
usefulness of these tools to study the effect of angular binning, the depth and
width of the survey and noise contributions due to intrinsic ellipticities and
number density of source galaxies on the estimation of cosmological parameters
is demonstrated. Results from independent analysis of various parameters and
joint estimations are compared. We also study how degeneracies among various
cosmological and survey parameters affect the eigenmodes associated with these
parameters.


title: Measuring the Magnetic Field on the Classical T Tauri Star TW Hydrae

abstract:
  We present infrared (IR) and optical echelle spectra of the Classical T Tauri
star TW Hydrae. Using the optical data, we perform detailed spectrum synthesis
to fit atomic and molecular absorption lines and determine key stellar
parameters: Teff = 4126 \pm 24 K, log g = 4.84 \pm 0.16, [M/H] = -0.10 \pm
0.12, vsini = 5.8 \pm 0.6 km/s. The IR spectrum is used to look for Zeeman
broadening of photospheric absorption lines. We fit four Zeeman sensitive Ti I
lines near 2.2 microns and find the average value of the magnetic field over
the entire surface is 2.61 \pm 0.23 kG. In addition, several nearby
magnetically insensitive CO lines show no excess broadening above that produced
by stellar rotation and instrumental broadening, reinforcing the magnetic
interpretation for the width of the Ti I lines. We carry out extensive tests to
quantify systematic errors in our analysis technique which may result from
inaccurate knowledge of the effective temperature or gravity, finding that
reasonable errors in these quantities produce a 10% uncertainty in the mean
field measurement.


title:
On the Ionisation Fraction in Protoplanetary Disks I: Comparing
  Different Reaction Networks

abstract:
  We calculate the ionisation fraction in protostellar disk models using a
number of different chemical reaction networks, including gas-phase and
gas-grain reaction schemes. The disk models we consider are conventional
alpha-disks, which include viscous heating and radiative cooling. The primary
source of ionisation is assumed to be X-ray irradiation from the central star.
We consider a number of gas-phase chemical networks. In general we find that
the simple models predict higher fractional ionisation levels and more
extensive active zones than the more complex models. When heavy metal atoms are
included the simple models predict that the disk is magnetically active
throughout. The complex models predict that extensive regions of the disk
remain magnetically uncoupled even with a fractional abundance of magnesium of
10(-8). The addition of submicron sized grains with a concentration of 10(-12)
causes the size of the dead zone to increase dramatically for all kinetic
models considered. We find that the simple and complex gas-grain reaction
schemes agree on the size and structure of the resulting dead zone. We examine
the effects of depleting the concentration of small grains as a crude means of
modeling the growth of grains during planet formation. We find that a depletion
factor of 10(-4) causes the gas-grain chemistry to converge to the gas-phase
chemistry when heavy metals are absent. 10(-8) is required when magnesium is
included. This suggests that efficient grain growth and settling will be
required in protoplanetary disks, before a substantial fraction of the disk
mass in the planet forming zone between 1 - 10 AU becomes magnetically active
and turbulent.


title:
Morphology and evolution of emission line galaxies in the Hubble Ultra
  Deep Field

abstract:
  We investigate the properties and evolution of a sample of galaxies selected
to have prominent emission lines in low-resolution grism spectra of the Hubble
Ultra Deep Field (HUDF). These objects, eGRAPES, are late type blue galaxies,
characterized by small proper sizes (R_50 < 2 kpc) in the 4350A rest-frame, low
masses (5x10^9 M_sun), and a wide range of luminosities and surface
brightnesses. The masses, sizes and volume densities of these objects appear to
change very little up to a redshift of z=1.5. On the other hand, their surface
brightness decreases significantly from z=1.5 to z=0 while their mass-to-light
ratio increases two-folds. This could be a sign that most of low redshift
eGRAPES have an older stellar population than high redshift eGRAPES and hence
that most eGRAPES formed at higher redshifts. The average volume density of
eGRAPES is (1.8 \pm 0.3)x10^{-3} Mpc^{-3} between 0.3 < z < 1.5. Many eGRAPES
would formally have been classified as Luminous Compact Blue Galaxies (LCBGs)
if these had been selected based on small physical size, blue intrinsic color,
and high surface brightness, while the remainder of the sample discussed in
this paper forms an extension of LCBGs towards fainter luminosities.


title:
Near-Infrared and Optical Limits for the Central X-ray Point Source in
  the Cassiopeia A Supernova Remnant

abstract:
  Near-infrared images of the center of the Cas A supernova remnant taken with
the NICMOS 2 camera on HST using the F110W and F160W filters (~J & ~H bands)
have magnitude limits of 26.2 and 24.6 respectively, but reveal no sources
within a 1.2" radius of the Chandra detected central X-ray point source (XPS).
The NICMOS data, taken together with broadband optical magnitude limits (R ~ 28
mag) obtained from a deep STIS CCD exposure taken with a clear filter (50CCD),
indicate that the XPS luminosities are very low in the optical/NIR bands (e.g.,
L_H < 3 x E29 erg/s) with no optical, J, or H band counterpart to the XPS
easily detectable by HST. We discuss the nature of the Cas A central compact
object based upon these new near-infrared and optical flux limits.


title:
On the Ionisation Fraction in Protoplanetary Disks II: The Effect of
  Turbulent Mixing on Gas--phase Chemistry

abstract:
  We calculate the ionisation fraction in protostellar disk models using two
different gas-phase chemical networks, and examine the effect of turbulent
mixing by modelling the diffusion of chemical species vertically through the
disk. The aim is to determine in which regions of the disk gas can couple to a
magnetic field and sustain MHD turbulence. We find that the effect of diffusion
depends crucially on the elemental abundance of heavy metals (magnesium)
included in the chemical model. In the absence of heavy metals, diffusion has
essentially no effect on the ionisation structure of the disks, as the
recombination time scale is much shorter than the turbulent diffusion time
scale. When metals are included with an elemental abundance above a threshold
value, the diffusion can dramatically reduce the size of the magnetically
decoupled region, or even remove it altogther. For a complex chemistry the
elemental abundance of magnesium required to remove the dead zone is 10(-10) -
10(-8). We also find that diffusion can modify the reaction pathways, giving
rise to dominant species when diffusion is switched on that are minor species
when diffusion is absent. This suggests that there may be chemical signatures
of diffusive mixing that could be used to indirectly detect turbulent activity
in protoplanetary disks. We find examples of models in which the dead zone in
the outer disk region is rendered deeper when diffusion is switched on. Overall
these results suggest that global MHD turbulence in protoplanetary disks may be
self-sustaining under favourable circumstances, as turbulent mixing can help
maintain the ionisation fraction above that necessary to ensure good coupling
between the gas and magnetic field.


title:
Starburst Models For FIR/sub-mm/mm Line Emission. I. An Expanding
  Supershell Surrounding A Massive Star Cluster

abstract:
  The effect of a newly born star cluster inside a giant molecular cloud (GMC)
is to produce a hot bubble and a thin, dense shell of interstellar gas and dust
swept up by the H II expansion, strong stellar winds, and repeated supernova
explosions. Lying at the inner side of the shell is the photodissociation
region (PDR), the origin of much of the far-infrared/sub-millimeter/millimeter
(FIR/sub-mm/mm) radiation from the interstellar medium (ISM). We present a
model for the expanding shell at different stages of its expansion which
predict mm/sub-mm and far-IR emission line intensities from a series of key
molecular and atomic constituents in the shell. The kinematic properties of the
swept-up shell predicted by our model are in very good agreement with the
measurements of the supershell detected in the nearby starburst galaxy M 82. We
compare the modeling results with the ratio-ratio plots of the FIR/sub-mm/mm
line emission in the central 1.0 kpc region to investigate the mechanism of
star forming activity in M 82. Our model has yielded appropriate gas densities,
temperatures, and structure scales compared to those measured in M 82, and the
total H2 content is compatible with the observations. This implies that the
neutral ISM of the central star-forming region is a product of fragments of the
evolving shells.


title: Large dust particles in disks around T Tauri stars

abstract:
  We present 7-mm continuum observations of 14 low-mass pre-main-sequence stars
in the Taurus-Auriga star-forming region obtained with the Very Large Array
with ~1.5" resolution and ~0.3 mJy rms sensitivity. For 10 objects, the
circumstellar emission has been spatially resolved. The large outer disk radii
derived suggest that the emission at this wavelength is mostly optically thin.
The millimetre spectral energy distributions are characterised by spectral
indices alpha = 2.3 to 3.2. After accounting for contribution from free-free
emission and corrections for optical depth, we determine dust opacity indices
beta in the range 0.5 to 1.6, which suggest that millimetre-sized dust
aggregates are present in the circumstellar disks. Four of the sources with
beta > 1 may be consistent with submicron-sized dust as found in the
interstellar medium. Our findings indicate that dust grain growth to
millimetre-sized particles is completed within less than 1 Myr for the majority
of circumstellar disks.


title: The sources of the Cosmic Infrared Background

abstract:
  The discovery of the Cosmic Infrared Background (CIB) in 1996, together with
recent cosmological surveys from the mid-infrared to the millimeter have
revolutionized our view of star formation at high redshifts. It has become
clear, in the last decade, that a population of galaxies that radiate most of
their power in the far-infrared (the so-called ``infrared galaxies'')
contributes an important part of the whole galaxy build-up in the Universe.
Since 1996, detailed (and often painful) investigations of the high-redshift
infrared galaxies have resulted in the spectacular progress reviewed in this
paper. Among others, we emphasize a new Spitzer result based on a Far-IR
stacking analysis of mid-IR sources.


title:
The Unique Type Ib Supernova 2005bf: A WN Star Explosion Model for
  Peculiar Light Curves and Spectra

abstract:
  Observations and modeling for the light curve (LC) and spectra of supernova
(SN) 2005bf are reported. This SN showed unique features: the LC had two
maxima, and declined rapidly after the second maximum, while the spectra showed
strengthening He lines whose velocity increased with time. The double-peaked LC
can be reproduced by a double-peaked $^{56}$Ni distribution, with most
$^{56}$Ni at low velocity and a small amount at high velocity. The rapid
post-maximum decline requires a large fraction of the $\gamma$-rays to escape
from the $^{56}$Ni-dominated region, possibly because of low-density ``holes''.
The presence of Balmer lines in the spectrum suggests that the He layer of the
progenitor was substantially intact. Increasing $\gamma$-ray deposition in the
He layer due to enhanced $\gamma$-ray escape from the $^{56}$Ni-dominated
region may explain both the delayed strengthening and the increasing velocity
of the He lines. The SN has massive ejecta ($\sim6-7\Msun$), normal kinetic
energy ($\sim 1.0-1.5\times 10^{51}$ ergs), high peak bolometric luminosity
($\sim 5\times 10^{42}$ erg s$^{-1}$) for an epoch as late as $\sim$ 40 days,
and a large $^{56}$Ni mass ($\sim0.32\Msun$). These properties, and the
presence of a small amount of H suggest that the progenitor was initially
massive (M$\sim 25-30 \Msun$) and had lost most of its H envelope, and was
possibly a WN star. The double-peaked $^{56}$Ni distribution suggests that the
explosion may have formed jets that did not reach the He layer. The properties
of SN 2005bf resemble those of the explosion of Cassiopeia A.


title:
A Search for Variable Stars and Planetary Occultations in NGC 2301 II:
  Variability

abstract:
  We performed R-band time series observations of the young, metal rich open
cluster NGC 2301 for 12 nights in Feb. 2004. B images were also obtained and
color magnitude diagrams, having limits of R=19.5 and B=21.5, were produced.
Only asmall effort was made to determine cluster membership as our magnitude
limits are far deeper than previously published values. Our photometric
precision, for the brightest 5 magnitudes of sources, is 1-2 mmag. We determine
that for the $\sim$4000 stars which have time-series data, 56% are variable and
of these, approximately 13% are observed to exhibit periodic light curves
ranging from tens of minutes to days. We present some examples of the light
curves obtained and produce cuts in variability space based on parameters such
as color and amplitude. The percentage of variability is approximately equal
across all colors with the majority of variables having amplitudes of 0.15
magnitudes or less. In general, redder stars show larger variability
amplitudes. We find a smooth decline in the number of periodic variables toward
longer period. This decline is probably due to a transition from intrinsic to
extrinsic variability and, in part, to our limited observing period of 12
nights. Essentially all the A and F main sequence stars in our sample are
variable ($\sim$2 mmag and larger) and most present complex light curves
containing multiple periods suggestive of their inclusion in the $\delta$Sct
and $\gamma$Dor classes. A variable non-cluster member giant and two variable
white dwarf candidates are discussed. Our equational description of variability
is shown to be an excellent predictive tool for determining the cumulative
fraction of variables that will be observed in a photometric survey. Our entire
dataset is available electronically.


title:
When less is more: Are radio galaxies below the Fanaroff-Riley break
  more polarized on parsec scales ?

abstract:
  We present images showing the first detections of polarization on parsec
scales in the nuclei of four Fanaroff-Riley type I (low-luminosity) radio
galaxies. Observations with Very Long Baseline Interferometry at \lambda 3.6cm
reveal the presence of ordered magnetic fields within ~1650 Schwarzchild radii
of the putative central supermassive black hole. The relatively high fractional
polarization in the pc-scale jets of these galaxies is consistent with the
standard scheme unifying low-luminosity radio galaxies with BL Lac objects.
This result also suggests that these radio galaxies lack the obscuring tori
that apparently depolarize the nuclear emission in the more powerful FRII radio
galaxies, and that their supermassive blackholes are poorly fed and/or
inefficient radiators.


title:
Surface density of the young cluster IC 348 in the Perseus molecular
  cloud

abstract:
  The IC 348 young star cluster contains more than 300 confirmed members. It is
embedded in the Perseus molecular cloud, making any clustering analysis subject
to an extinction bias. In this work, we derive the extinction map of the cloud
and revisit the content of IC 348 through a statistical approach that uses the
2MASS data. Our goal was to address the question of the completeness of IC 348
and of young clusters in general. We performed a combined analysis of the star
color and density in this region, in order to establish the surface density map
of the cluster. We reached the conclusion that IC 348 has structures up to 25'
from the cluster center, and we estimate that about 40 members brighter than
Ks=13 mag are still unidentified. Although we cannot use our statistical method
to identify these new members individually, the surface density map gives a
strong indication of their actual location. They are distributed in the outer
regions of the cluster, where very few dedicated observations have been made so
far, which is probably why they escaped previous identification. In addition,
we propose the existence of a new embedded cluster associated to the infrared
source MSX6C G160.2784-18.4216, about 38' south of IC 348.


title:
Local Group Dwarf Elliptical Galaxies: I. Mapping the Dynamics of NGC
  205 Beyond the Tidal Radius

abstract:
  NGC 205 is the nearest example of a dwarf elliptical (dE) galaxy and the
prototype of this enigmatic galaxy class. Photometric evidence suggests that
NGC 205, a close satellite of the M31 galaxy, is tidally interacting with its
parent galaxy. We present stellar radial velocity measurements out to a
projected radius of 20' (5 kpc) in NGC 205 based on Keck/DEIMOS multislit
spectroscopic observations of 725 individual red giant branch stars. Our
kinematic measurements extend from the center out to six times the effective
radius of NGC 205, well past the expected tidal radius. The contamination in
our kinematic sample from M31 field stars is estimated to be a few percent
based on maximum likelihood fits. We measure a maximum major-axis rotation
speed for the body of NGC 205 of 11+/- 5 kms; this is the first dE galaxy in
which the maximum rotation velocity has been measured. Combined with the
velocity dispersion, we conclude that NGC 205 is supported by a combination of
rotation and random motions. At a major-axis distance of 4.5' (1 kpc), the
velocity profile of NGC 205 turns over; stars beyond this radius are moving
counter to the rotation of the inner part of the galaxy. The turnover radius is
coincident with the onset of isophotal twisting and the estimated tidal radius,
suggesting that the outer kinematics of NGC 205 are dominated by gravitational
interactions with the nearby M31 galaxy. The motion of stars beyond a radius of
4.5' implies that NGC 205 is in a prograde encounter with its parent galaxy
M31.


title: The High-Velocity Outflow of PG1211+143 May Not be That Fast

abstract:
  We analyze the X-ray spectrum of the quasar PG1211+143 observed with the CCD
and grating spectrometers on board XMM-Newton. Using an ion by ion fitting
model we find an outflow component of about 3000 km/s that includes absorption
lines of K-shell and L-shell ions of the astrophysically abundant elements. We
also identify and include in our model broad (FWHM = 6000 km/s) emission lines
from H-like ions of C, N, O, and Ne, and He-like ions of O, Ne, and Mg. The
outflow velocity we find is an alternative interpretation of the data and is in
contrast with the ultra high velocity of ~24000 km/s reported previously for
this object. Nevertheless, we can not completely rule out the presence of a
high velocity component due to the poor signal-to-noise ratio of the data.


title:
The matter power spectrum from the Lyman-alpha forest: an optical depth
  estimate

abstract:
  We measure the matter power spectrum from the Lyman-alpha forest of 31 quasar
spectra spanning the redshift range of 1.6-3.6. The optical depth, $\tau$, for
absorption of the intergalactic medium is obtained from the flux using the
inversion method of Nusser & Haehnelt (1999). The optical depth is converted to
density by using a simple power law relation, $\tau \propto (1+\delta)^\alpha$.
The non-linear 1D power spectrum of the gas density is then inferred with a
method that makes simultaneous use of the 1 and 2 point statistics of the flux
and compared against theoretical models with a likelihood analysis. A Cold Dark
Matter (CDM) model with standard cosmological parameters fits the data well.
The power spectrum amplitude is measured to be (assuming a flat Universe),
$\sigma_8 = (0.9 \pm 0.09)\times (\Omega_{\rm m}/0.3)^{-0.3}$, with $\alpha$
varying in the range of $1.56-1.8$ with redshift. Enforcing the same
cosmological parameters in all four redshift bins, the likelihood analysis
suggests some evolution in the density-temperature relation and the thermal
smoothing length of the gas. The inferred evolution is consistent with that
expected if reionization of \hep occurred at $z\sim 3.2$. A joint analysis with
the WMAP results together with a prior on the Hubble constant as suggested by
the HST key project data, yields values of $\Omega_{\rm m}$ and $\sigma_8$ that
are consistent with the cosmological concordance model. We also perform a
further inversion to obtain the linear 3D power spectrum of the matter density
fluctuations.


title:
Clustering of Lyman Break Galaxies at z=4 and 5 in The Subaru Deep
  Field: Luminosity Dependence of The Correlation Function Slope

abstract:
  We explored the clustering properties of Lyman Break Galaxies (LBGs) at z=4
and 5 with an angular two-point correlation function on the basis of the very
deep and wide Subaru Deep Field data. We found an apparent dependence of the
correlation function slope on UV luminosity for LBGs at both z=4 and 5. More
luminous LBGs have a steeper correlation function. To compare these
observational results, we constructed numerical mock LBG catalogs based on a
semianalytic model of hierarchical clustering combined with high-resolution
N-body simulation, carefully mimicking the observational selection effects. The
luminosity functions for LBGs predicted by this mock catalog were found to be
almost consistent with the observation. Moreover, the overall correlation
functions of LBGs were reproduced reasonably well. The observed dependence of
the clustering on UV luminosity was not reproduced by the model, unless
subsamples of distinct halo mass were considered. That is, LBGs belonging to
more massive dark haloes had steeper and larger-amplitude correlation
functions. With this model, we found that LBG multiplicity in massive dark
halos amplifies the clustering strength at small scales, which steepens the
slope of the correlation function. The hierarchical clustering model could
therefore be reconciled with the observed luminosity-dependence of the angular
correlation function, if there is a tight correlation between UV luminosity and
halo mass. Our finding that the slope of the correlation function depends on
luminosity could be an indication that massive dark halos hosted multiple
bright LBGs (abridged).


title:
A New Signature of Dark Matter Annihilations: Gamma-Rays from
  Intermediate-Mass Black Holes

abstract:
  We study the prospects for detecting gamma-rays from Dark Matter (DM)
annihilations in enhancements of the DM density (mini-spikes) around
intermediate-mass black holes with masses in the range $10^2 \lsim M / \msun
\lsim 10^6$. Focusing on two different IMBH formation scenarios, we show that,
for typical values of mass and cross section of common DM candidates,
mini-spikes, produced by the adiabatic growth of DM around pregalactic IMBHs,
would be bright sources of gamma-rays, which could be easily detected with
large field-of-view gamma-ray experiments such as GLAST, and further studied
with smaller field-of-view, larger-area experiments like Air Cherenkov
Telescopes CANGAROO, HESS, MAGIC and VERITAS. The detection of many gamma-ray
sources not associated with a luminous component of the Local Group, and with
identical cut-offs in their energy spectra at the mass of the DM particle,
would provide a potential smoking-gun signature of DM annihilations and shed
new light on the nature of intermediate and supermassive Black Holes.


title:
The Diverse Infrared Properties of a Complete Sample of Star-Forming
  Dwarf Galaxies

abstract:
  We present mid-infrared Spitzer Space Telescope observations of a complete
sample of star-forming dwarf galaxies selected from the KPNO International
Spectroscopic Survey. The galaxies span a wide range in mid-infrared
properties. Contrary to expectations, some of the galaxies emit strongly at 8
micron indicating the presence of hot dust and/or PAHs. The ratio of this
mid-infrared dust emission to the stellar emission is compared with the
galaxies' luminosity, star-formation rate, metallicity, and optical reddening.
We find that the strength of the 8.0 micron dust emission to the stellar
emission ratio is more strongly correlated with the star-formation rate than it
is with the metallicity or the optical reddening in these systems. Nonetheless,
there is a correlation between the 8.0 micron luminosity and metallicity. The
slope of this luminosity-metallicity correlation is shallower than
corresponding ones in the B-band and 3.6 micron. The precise nature of the 8.0
micron emission seen in these galaxies (i.e., PAH versus hot dust or some
combination of the two) will require future study, including deep mid-IR
spectroscopy.


title:
An Unusual Spectral State of an Ultra-luminous Very Soft X-ray Source
  during Outburst

abstract:
  We report the results of Chandra and XMM-Newton observations of a new
outburst of an ultra-luminous X-ray source in M101. During a Chandra monitoring
observation of M101, M101 ULX-1 was found to be in outburst in 2004 December,
the second outburst in 2004. The peak bolometric luminosity is about 3e40 erg/s
(7e39 erg/s in 0.3-7 keV). The outburst spectra are very soft and can generally
be fitted with a blackbody model with temperatures of 40-80 eV, similar to
supersoft X-ray sources in the Milky Way and in the Magellanic Clouds. In one
Chandra observation, the source spectrum appears to be harder with a
temperature of 150 eV. Such a spectral state is rarely seen in M101 ULX-1 and
no X-ray source in the Milky Way shows this kind of spectrum. However, such an
unusual spectral state very likely belongs to a new class of X-ray sources,
quasisoft X-ray sources, recently discovered in nearby galaxies. M101 ULX-1
returned to supersoft state in a subsequent XMM-Newton observation. Based on
the two outbursts in 2004, the extremely high luminosity (L_bol=1e40-1e41
erg/s), very soft X-ray spectra (kT=40-150 eV), transient behavior, and state
transition provide strong evidence that M101 ULX-1 harbors an intermediate-mass
black hole.


title:
Spatially-Resolved Narrow Line Region Kinematics in Active Galactic
  Nuclei

abstract:
  We have analyzed HST spectroscopy of 24 nearby AGNs to investigate
spatially-resolved gas kinematics in the Narrow Line Region (NLR). These
observations effectively isolate the nuclear line profiles on less than 100 pc
scales and are used to investigate the origin of the substantial scatter
between the widths of strong NLR lines and the stellar velocity dispersion
sigma_* of the host galaxy, a quantity which relates with substantially less
scatter to the mass of the central, supermassive black hole, and more generally
characterize variations in the NLR velocity field with radius. We find that
line widths measured with STIS at a range of spatial scales systematically
underestimate both sigma_* and the line width measured from ground-based
observations, although they do have comparably large scatter to the relation
between ground-based NLR line width and sigma_*. There are no obvious trends in
the residuals when compared with a range of host galaxy and nuclear properties.
The widths and asymmetries of [OIII] 5007 and [SII] 6716, 6731 as a function of
radius exhibit a wide range of behavior. Some of the most common phenomena are
substantial width increases from the STIS to the large-scale, ground-based
aperture and almost no change in line profile between the unresolved nuclear
spectrum and ground-based measurements. We identify asymmetries in a
surprisingly large fraction of low-ionization [SII] line profiles and several
examples of substantial red asymmetries in both [OIII] and [SII]. These results
underscore the complexity of the circumnuclear material that constitutes the
NLR and suggest that the scatter in the NLR width and sigma_* correlation can
not be substantially reduced with a simple set of empirical relations.


title:
Investigating the Late Stages of Stellar Evolution with Long Period
  Variables from MACHO and 2MASS

abstract:
  We are re-analyzing the MACHO variable star database to explore the
relationships between pulsation, evolution, and mass loss in evolved stars. We
will analyze the multi-periodic properties of long period variable (LPV) stars,
50% of which could not be assigned any period in the original analysis. Recent
results show that the missing stars may be an important element in
understanding the origin of the period-luminosity sequences observed in the
LMC. Our goal is to characterize the morphology and periodic properties of
these stars, and then use the stars' 2MASS colors along with theoretical
isochrones to understand their mass loss and evolution. We will develop a
luminosity-independent criteria to classify the LMC LPVs, which can then be
applied to Galactic LPVs. This will enable a synthesis of knowledge between
LPVs in the LMC and the well-studied Galactic examples.


title: Neutrino-Induced Cascades From GRBs With AMANDA-II

abstract:
  Using AMANDA-II we have performed a search for neutrino-induced cascades in
coincidence with 73 bursts reported by BATSE in 2000. Background is greatly
suppressed by the BATSE temporal constraint. No evidence of neutrinos was
found. We set a limit on a WB-like spectrum, $A_{90}^{all flavors}$ =
9.5$\times10^{-7}$ GeV cm$^{-2}$ s$^{-1}$ sr$^{-1}$. The determination of
systematic uncertainties is in progress, and the limit will be somewhat
weakened once these uncertainties are taken into account. We are also
conducting a rolling time-window search for neutrino-induced cascades
consistent with a GRB signal in 2001. The data set is searched for a
statistically significant cluster of signal-like events within a 1 s or 100 s
time window. The non-triggered search has the potential to discover phenomena,
including gamma-ray dark choked bursts, which did not trigger gamma-ray
detectors.


title: Gamma-Ray Burst Early Afterglows

abstract:
  The successful launch and operation of NASA's Swift Gamma-Ray Burst Explorer
open a new era for the multi-wavelength study of the very early afterglow phase
of gamma-ray bursts (GRBs). GRB early afterglow information is essential to
explore the unknown physical composition of GRB jets, the link between the
prompt gamma-ray emission and the afterglow emission, the GRB central engine
activity, as well as the immediate GRB environment. Here I review some of the
recent theoretical efforts to address these problems and describe how the
latest Swift data give answers to these outstanding questions.


title:
Optical Photometric and Spectroscopic study of the Seyfert Galaxy SBS
  0748+499

abstract:
  We present the first optical photometric study of the active galaxy SBS
0748+499. First, we present B, V, R and I photometric data: total magnitudes
and B-V, B-R, B-I colors; surface brightness, color and geometric profiles,
with emphasis on the morphology and its relation to the global photometric
properties of this galaxy. Then, from our surface photometry study we derive
the bulge-to-disk luminosity ratio B/D in the four bands. We find that the host
galaxy shows a bar (a ~ 8 kpc) and a low-brightness spiral structure. The
morphological classification for the host galaxy of this AGN is SBab.
Additionally, we present new optical spectrophotometric observations that
clearly show that the object can be classified as Sy 1.9 galaxy. Finally, we
estimate the black hole mass (M_BH) associated with the nucleus of SBS 0748+499
using the absolute R-band bulge magnitude - M_BH relation, and the FWHM
[OIII]_5007 - sigma_{star} relation. We find that M_BH = 2.6 x 10^7 M(sun) and
M_BH = 8.8 x 10^7 M(sun), respectively.


title:
Protostellar mergers in protoclusters and the origin of ultra-luminous
  X-ray sources

abstract:
  I suggest that stellar coalescence in mid-size protoclusters (M ~ 10^{3.5} -
10^{4.5} M_sun) is a possible scenario for the formation of ultra-luminous
X-ray sources (ULXs). More massive super-star-clusters are not needed, since
the most likely ULX mass range is only ~ 30--200 M_sun; in fact, they are very
rarely found at or very near ULX positions. Protostellar envelopes and gas
accretion favour captures and mergers in dense cores of embedded clusters.
Moreover, protoclusters with masses ~ 10^{3.5} - 10^{4.5} M_sun are likely to
disperse quickly into loose OB associations, where most ULXs are found.
Sufficiently high protostellar density may be achieved when clustered star
formation is triggered by galaxy collisions and mergers. Low metallicity may
then be necessary to ensure that a large fraction of the stellar mass ends up
in a black hole. In this scenario, most ULXs are naturally explained as the
extreme end of the high-mass X-ray binary population.


title:
X-ray and Optical Eclipses in ULXs as Possible Indicators of Black Hole
  Mass

abstract:
  Ultraluminous X-ray sources (ULXs) with 10^39 < L_x < 10^41 erg/s have been
discovered in great numbers in external galaxies with ROSAT, Chandra, and
XMM-Newton. The central question regarding this important class of sources is
whether they represent an extension in the luminosity function of binary X-ray
sources containing neutron stars and stellar-mass black holes (BHs), or a new
class of objects, e.g., systems containing intermediate-mass black holes (100 -
1000 M_sun). We suggest searching for X-ray and optical eclipses in these
systems to provide another diagnostic to help distinguish between these two
possibilities. The sense of the effect is that ULXs with stellar-mass black
hole accretors should be at least twice as likely to exhibit eclipses as
intermediate-mass black hole systems - and perhaps much more than a factor of
two. Among other system parameters, the orbital period would follow. This would
provide considerable insight as to the nature of the binary.


title: Cluster Evolution Since z~1

abstract:
  We have used the Advanced Camera for Surveys (ACS) on the HST to obtain
optical imaging of a sample of 8 galaxy clusters in the redshift range 0.8 < z
< 1.3. The ACS data provides accurate photometry and the ACS high angular
resolution makes it possible to obtain crucial morphological information of the
cluster galaxy populations. These data are supported by X-ray observations and
by ground based imaging and multi-object spectroscopy. We will present results
from this multi-wavelength study which is providing a comprehensive view of the
evolution of structures in the universe since z~1. The structure of the ICM,
galaxy and DM components of the clusters are presented and compared. The
spectrophotometric properties of cluster galaxies are investigated in the
context of galaxy evolution and the formation epoch of massive early-type
galaxies in these clusters is estimated to be at z > 2. We will also present
results from our study of the evolution of the Morphology-Density relation in
clusters since z~1 down to the present day universe. Our cluster evolution
studies are also being complemented by observations of protoclusters at
redshift z>~2.


title:
Galactic metric, dark radiation, dark pressure and gravitational lensing
  in brane world models

abstract:
  In the braneworld scenario, the four dimensional effective Einstein equation
has extra terms which arise from the embedding of the 3-brane in the bulk.
These non-local effects, generated by the free gravitational field of the bulk,
may provide an explanation for the dynamics of the neutral hydrogen clouds at
large distances from the galactic center, which is usually explained by
postulating the existence of the dark matter. We obtain the exact galactic
metric, the dark radiation and the dark pressure in the flat rotation curves
region in the brane world scenario. Due to the presence of the bulk effects,
the flat rotation curves could extend several hundred kpc. The limiting radius
for which bulk effects are important is estimated and compared with the
numerical values of the truncation parameter of the dark matter halos, obtained
from weak lensing observations. There is a relatively good agreement between
the predictions of the model and observations. The deflection of photons is
also considered and the bending angle of light is computed. The bending angle
predicted by the brane world models is much larger than that predicted by
standard general relativistic and dark matter models. The angular radii of the
Einstein rings are obtained in the small angles approximation. The predictions
of the brane world model for the tangential shear are compared with the
observational data obtained in the weak lensing of galaxies in the Red-Sequence
Cluster Survey. Therefore the study of the light deflection by galaxies and the
gravitational lensing could discriminate between the different dynamical laws
proposed to model the motion of particles at the galactic level and the
standard dark matter models.


title: Measurements of Atmospheric Antiprotons

abstract:
  We measured atmospheric antiproton spectra in the energy range 0.2 to 3.4
GeV, at sea level and at balloon altitude in the atmospheric depth range 4.5 to
26 g/cm^2. The observed energy spectra, including our previous measurements at
mountain altitude, were compared with estimated spectra calculated on various
assumptions regarding the energy distribution of antiprotons that interacted
with air nuclei.


title:
Ring shaped 6.7 GHz methanol maser emission around a young high-mass
  star

abstract:
  We report on EVN imaging of the 6.7 GHz methanol maser emission from the
candidate high-mass protostar G23.657-0.127. The masers originate in a nearly
circular ring of 127 mas radius and 12 mas width. The ring structure points at
a central exciting object which characteristics are typical for a young massive
star; its bolometric luminosity is estimated to be <3.2*10^4 L_sun and
<1.2*10^5 L_sun for near (5.1 kpc) and far (10.5 kpc) kinematic distances,
respectively. However, the spatial geometry of the underlying maser region
remains ambiguous. We consider scenarios in which the methanol masers originate
in a spherical bubble or in a rotating disc seen nearly face-on.


title: Cosmology from supernova magnification maps

abstract:
  High-z Type Ia supernovae are expected to be gravitationally lensed by the
foreground distribution of large-scale structure. The resulting magnification
of supernovae is statistically measurable, and the angular correlation of the
magnification pattern directly probes the integrated mass density along the
line of sight. Measurements of cosmic magnification of supernovae therefore
complements galaxy shear measurements in providing a direct measure of
clustering of the dark matter. As the number of supernovae is typically much
smaller than the number of sheared galaxies, the two-point correlation function
of lensed Type Ia supernovae suffers from significantly increased shot noise.
Neverthless, we find that the magnification map of a large sample of
supernovae, such as that expected from next generation dedicated searches, will
be easily measurable and provide an important cosmological tool. For example, a
search over 20 sq. deg. over five years leading to a sample of ~ 10,000
supernovae would measure the angular power spectrum of cosmic magnification
with a cumulative signal-to-noise ratio of ~20. This detection can be further
improved once the supernova distance measurements are cross-correlated with
measurements of the foreground galaxy distribution. The magnification maps made
using supernovae can be used for important cross-checks with traditional
lensing shear statistics obtained in the same fields, as well as help to
control systematics. We discuss two applications of supernova magnification
maps: the breaking of the mass-sheet degeneracy when estimating masses of
shear-detected clusters, and constraining the second-order corrections to weak
lensing observables.


title:
High-frequency radio observations of the Kuehr sample and the
  epoch-dependent luminosity function of the flat-spectrum quasars

abstract:
  We discuss our ATCA 18.5 and 22 GHz flux density measurements of the Southern
extragalactic sources in the complete 5-GHz sample of Kuehr et al. (1981). The
high-frequency (5-18.5 GHz) spectral indices of steep-spectrum sources for
which we have 18.5-GHz data (66% of the complete sample) are systematically
steeper than the low-frequency (2.7-5 GHz) ones, and there is evidence of an
anti-correlation of high-frequency spectral index with luminosity. The
completeness of the 18.5-GHz data is much higher (89%) for flat-spectrum
sources (mostly quasars), which also exhibit a spectral steepening. Taking
advantage of the almost complete redshift information on flat-spectrum quasars,
we have estimated their 5-GHz luminosity function in several redshift bins. The
results confirm that their radio luminosity density peaks at z_peak \simeq 2.5
but do not provide evidence for deviations from pure luminosity evolution as
hinted at by other data sets. A comparison of our 22-GHz flux density with WMAP
K-band data for flat-spectrum sources suggests that WMAP flux densities may be
low by a median factor of \simeq 1.2. The extrapolations of 5-GHz counts and
luminosity functions of flat-spectrum radio quasars using the observed
distribution of the 5-18.5 GHz spectral indices match those derived directly
from WMAP data, indicating that the high-frequency WMAP survey does not detect
any large population of FSRQs with anomalous spectra.


title:
Problems with Pencils: Lensing Covariance of Supernova Distance
  Measurements

abstract:
  While luminosity distances from Type Ia supernovae (SNe) provide a powerful
probe of cosmological parameters, the accuracy with which these distances can
be measured is limited by cosmic magnification due to gravitational lensing by
the intervening large-scale structure. Spatial clustering of foreground mass
fluctuations leads to correlated errors in distance estimates from SNe. By
including the full covariance matrix of supernova distance measurements, we
show that a future survey covering more than a few square degrees on the sky,
and assuming a total of ~2000 SNe, will be largely unaffected by covariance
noise. ``Pencil beam'' surveys with small fields of view, however, will be
prone to the lensing covariance, leading to potentially significant
degradations in cosmological parameter estimates. For a survey with 30 arcmin
mean separation between SNe, lensing covariance leads to a ~45% increase in the
expected errors in dark energy parameters compared to fully neglecting lensing,
and a ~20% increase compared to including just the lensing variance. Given that
the lensing covariance is cosmology dependent and cannot be mapped out
sufficiently accurately with direct weak lensing observations, surveys with
small mean SN separation must incorporate the effects of lensing covariance,
including its dependence on the cosmological parameters.


title:
A simple varying-speed-of-light hypothesis is enough for explaining
  high-redshift supernovae data

abstract:
  The hypothesis that the speed of light decreases by nearly 2 cm per sec and
per year is discussed within the frame of a simple phenomenological model. It
is shown that this hypothesis can provide an alternative explanation for the
redshift-distance relationship of type Ia supernovae, which is nowadays given
in terms of a new form of (dark) energy of unknown origin.


title:
Cumulative luminosity functions of the X-ray point source population in
  M31

abstract:
  We present preliminary results from a detailed analysis of the X-ray point
sources in the XMM-Newton survey of M31. These sources are expected to be
mostly X-ray binaries. We have so far studied 225 of the 535 sources found by
automated source detection. Only sources which were present in all three EPIC
images were considered. X-ray binaries are identified by their energy spectrum
and power density spectrum. Unlike in other surveys we have obtained source
luminosities from freely fit emission models. We present uncorrected luminosity
functions of the sources analysed so far.


title:
X-ray Spectral Survey with XMM--Newton of a Complete Sample of Nearby
  Seyfert Galaxies

abstract:
  Results obtained from an X-ray spectral survey of nearby Seyfert galaxies
using XMM--Newton are reported. The sample was optically selected, well
defined, complete in B mag, and distance limited: it consists of the nearest
(D<22 Mpc) 27 Seyfert galaxies (9 of type 1, 18 of type 2) taken from the Ho et
al. (1997) sample. This is one of the largest atlases of hard X-ray spectra of
low-L active galaxies ever assembled. All nuclear sources except two Sey 2s are
detected between 2-10 keV, half for the first time ever, and average spectra
are obtained for all of them. Nuclear luminosities reach values down to 10**38
erg/s. The shape of the distribution of X-ray parameters is affected by the
presence of Compton-thick objects (> 30% among type 2s). The latter have been
identified either directly from their intense FeK line and flat X-ray spectra,
or indirectly with flux diagnostic diagrams which use isotropic indicators.
After taking into account these highly absorbed sources, we find that (i) the
intrinsic X-ray spectral properties (i.e., spectral shapes and luminosities
above 2 keV) are consistent between type 1 and type 2 Sey, as expected from
``unified models'', (ii) Sey galaxies as a whole are distributed fairly
continuously over the entire range of Nh, between 10**20 and 10**25 cm**-2, and
(iii) while Sey 1s tend to have lower Nh and Sey 2s tend to have the highest,
we find 30% and 10% exceptions, respectively. Overall the sample well
represents the average intrinsic X-ray spectral properties of nearby AGN,
including a proper estimate of the distribution of their absorbing columns.
Finally, we conclude that, with the exception of a few cases, the present study
agrees with predictions of unified models of Sey galaxies, and extends their
validity down to very low luminosities.


title: Low-column density gas clumps in the halo of the Milky Way

abstract:
  We report on the detection of low-column density neutral hydrogen clumps in
the halo of the Milky Way. Using high-resolution (FWHM~7 km/s) optical spectra
obtained with the VLT/UVES spectrograph we detect narrow interstellar
absorption by CaII and NaI at high radial velocities near -150 km/s toward the
quasar PKS 1448-232 (l=335.4, b=+31.7). Follow-up HI 21cm observations with the
VLA unveil the presence of a complex of small neutral hydrogen clumps with HI
column densities <8x10^18 cm^-2. The measured HI line widths imply that the gas
is relatively cold with temperatures T<900 K. Although the line of sight
towards PKS 1448-232 does not pass immediately through a known large
high-velocity cloud (HVC), the sky position and the measured radial velocities
suggest that these clumps are associated with HVC cloud complex L. An
inspection of other UVES quasar spectra shows that weak, narrow CaII absorption
at high velocities is a common phenomenon, even in directions where
high-velocity HI 21cm emission is not detected. This suggests that the Milky
Way halo contains a large number of high-velocity neutral gas clumps with low
HI column densities. If such clumps are typical for halos of spiral galaxies,
they should contribute significantly to the population of strong MgII absorbers
and Lyman-Limit Systems (LLS) seen in the circumgalactic environment of other
galaxies.


title:
Estimated IR and phosphorescence emission fluxes for specific Polycyclic
  Aromatic Hydrocarbons in the Red Rectangle

abstract:
  Following the tentative identification of the blue luminescence in the Red
Rectangle by Vijh et al. (2005), we compute absolute fluxes for the vibrational
IR emission and phosphorescence bands of three small polycyclic aromatic
hydrocarbons. The calculated IR spectra are compared with available ISO
observations. A subset of the emission bands are predicted to be observable
using presently available facilities, and can be used for an immediate,
independent, discriminating test on their alleged presence in this well-known
astronomical object.


title:
Accelerator Testing of the General Antiparticle Spectrometer, a Novel
  Approach to Indirect Dark Matter Detection

abstract:
  We report on recent accelerator testing of a prototype general antiparticle
spectrometer (GAPS). GAPS is a novel approach for indirect dark matter searches
that exploits the antideuterons produced in neutralino-neutralino
annihilations. GAPS captures these antideuterons into a target with the
subsequent formation of exotic atoms. These exotic atoms decay with the
emission of X-rays of precisely defined energy and a correlated pion signature
from nuclear annihilation. This signature uniquely characterizes the
antideuterons. Preliminary analysis of data from a prototype GAPS in an
antiproton beam at the KEK accelerator in Japan has confirmed the
multi-X-ray/pion star topology and indicated X-ray yields consistent with prior
expectations. Moreover our success in utilizing solid rather than gas targets
represents a significant simplification over our original approach and offers
potential gains in sensitivity through reduced dead mass in the target area.


title: What is the temperature structure in the giant HII region NGC 588?

abstract:
  We present the results of an exhaustive study of the ionized gas in NGC 588,
a giant H II region in the nearby spiral galaxy M33. This analysis uses a high
number of diagnostics in the optical and infrared ranges. Four temperature
diagnostics obtained with optical lines agree with a gas temperature of 11000K,
while the [O III] 5007/88um ratio yields a much lower temperature of 8000K
approximately. This discrepancy suggests the presence of large temperature
inhomogeneities in the nebula. We investigated the cause of this discrepancy by
constructing photoionization models of increasing complexity. In particular, we
used the constraints from the Halpha and Hbeta surface brightness distributions
and state-of-the-art models of the stellar ionizing spectrum. None of the
successive attempts was able to reproduce the discrepancy between the
temperature diagnostics, so the thermal balance of NGC 588 remains unexplained.
We give an estimate of the effect of this failure on the O/H and Ne/O estimates
and show that O/H is known to within +/-0.2 dex


title: Odin detection of O2

abstract:
  We present the detection of molecular oxygen with Odin toward the dense
molecular core rho Oph A, which is part of a region of active star formation.
The observed spectral line is the (N,J = 1,1-1,0) ground state transition of
molecular oxygen at 119 GHz (2.5 mm wavelength). The center of the line is at
the LSR velocity of a number of optically thin lines from other species in the
region and the O2 line also has a very similar, narrow, line width. Within the
10 arcmin beam, the integrated line intensity is 28 mK km/s, which corresponds
to 5 sigma of the rms noise. A standard LTE analysis results in an O2 abundance
of 5E(-8), with an uncertainty of at least a factor of two. We show that
standard methods, however, do not apply in this case, as the coupling of the
Odin beam to the source structure needs to be accounted for. Preliminary model
results indicate O2 abundances to be higher by one order of magnitude than
suggested by the standard case. This model predicts the 487 GHz line of O2 to
be easily detectable by the future Herschel-HIFI facility, but to be out of
reach for observations on a shorter time scale with the Odin space observatory.


title: Testing Bekenstein's Relativistic MOND gravity with Lensing Data

abstract:
  We propose to use multiple-imaged gravitational lenses to set limits on
gravity theories without dark matter, specificly TeVeS (Bekenstein 2004), a
theory which is consistent with fundamental relativistic principles and the
phenomenology of MOdified Newtonian Dynamics (MOND) theory. After setting the
framework for lensing and cosmology, we derive analytically the deflection
angle for the point lens and the Hernquist galaxy profile, and fit
galaxy-quasar lenses in the CASTLES sample. We do this with three methods,
fitting the observed Einstein ring sizes, the image positions, or the flux
ratios. In all cases we consistently find that stars in galaxies in MOND/TeVeS
provide adequate lensing. Bekenstein's toy $\mu$ function provides more
efficient lensing than the standard MOND $\mu$ function. But for a handful of
lenses [indicated in Table 2,3, fig 16] a good fit would require a lens mass
orders of magnitude larger/smaller than the stellar mass derived from
luminosity unless the modification function $\mu$ and modification scale $a_0$
for the universal gravity were allowed to be very different from what spiral
galaxy rotation curves normally imply. We discuss the limitation of present
data and summarize constraints on the MOND $\mu$ function. We also show that
the simplest TeVeS "minimal-matter" cosmology, a baryonic universe with a
cosmological constant, can fit the distance-redshift relation from the
supernova data, but underpredicts the sound horizon size at the last
scattering. We conclude that lensing is a promising approach to differentiate
laws of gravity (see also astro-ph/0512425).


title:
The Mass Spectra of Cores in Turbulent Molecular Clouds and Implications
  for the Initial Mass Function

abstract:
  We investigate the core mass distribution (CMD) resulting from numerical
models of turbulent fragmentation of molecular clouds. In particular we study
its dependence on the sonic root-mean-square Mach number $\Ms$. We analyze
simulations with $\Ms$ ranging from 1 to 15 to show that, as $\Ms$ increases,
the number of cores increases as well while their average mass decreases. This
stems from the fact that high-Mach number flows produce many and strong shocks
on intermediate to small spatial scales, leading to a highly-fragmented density
structure. We also show that the CMD from purely turbulent fragmentation does
not follow a single power-law, but it may be described by a function that
changes continuously its shape, probably more similar to a log-normal function.
The CMD in supersonic turbulent flows does not have a universal slope, and as
consequence, cast some doubt on attempts to directly relate the CMD to a
universal Initial Mass Function.


title: Unifying dark energy and dark matter with a scalar field

abstract:
  The standard model of cosmology considers the existence of two components of
unknown nature, ``dark matter'' and ``dark energy'', which determine the
cosmological evolution. Their nature remains unknown, and other models can also
be considered. In particular, it may be possible to reinterpret the recent
cosmological observations so that the Universe does not contain two fluids of
unknown natures, but only one fluid with particular properties. After a brief
review of constraints on this unifying ``dark fluid'', we will discuss a
specific model of dark fluid based on a complex scalar fluid.


title: The environmental dependence of clustering in hierarchical models

abstract:
  In hierarchical models, density fluctuations on different scales are
correlated. This induces correlations between dark halo masses, their formation
histories, and their larger-scale environments. In turn, this produces a
correlation between galaxy properties and environment. This correlation is
entirely statistical in nature. We show how the observed clustering of galaxies
can be used to quantify the importance of this statistical correlation relative
to other physical effects which may also give rise to correlations between the
properties of galaxies and their surroundings. We also develop a halo model
description of this environmental dependence of clustering.


title: Optical Lightcurve & Cooling Break of GRB 050502A

abstract:
  We present lightcurves of the afterglow of GRB050502A, including very early
data at t-t_{GRB} < 60s. The lightcurve is composed of unfiltered ROTSE-IIIb
optical observations from 44s to 6h post-burst, R-band MDM observations from
1.6 to 8.4h post-burst, and PAIRITEL J H K_s observations from 0.6 to 2.6h
post-burst. The optical lightcurve is fit by a broken power law, where
t^{alpha} steepens from alpha = -1.13 +- 0.02 to alpha = -1.44 +- 0.02 at
\~5700s. This steepening is consistent with the evolution expected for the
passage of the cooling frequency nu_c through the optical band. Even in our
earliest observation at 44s post-burst, there is no evidence that the optical
flux is brighter than a backward extrapolation of the later power law would
suggest. The observed decay indices and spectral index are consistent with
either an ISM or a Wind fireball model, but slightly favor the ISM
interpretation. The expected spectral index in the ISM interpretation is
consistent within 1 sigma with the observed spectral index beta = -0.8 +- 0.1;
the Wind interpretation would imply a slightly (~2 sigma) shallower spectral
index than observed. A small amount of dust extinction at the source redshift
could steepen an intrinsic spectrum sufficiently to account for the observed
value of beta. In this picture, the early optical decay, with the peak at or
below 4.7e14 Hz at 44s, requires very small electron and magnetic energy
partitions from the fireball.


title: A Gravitational Tractor for Towing Asteroids

abstract:
  We present a concept for a spacecraft that can controllably alter the
trajectory of an Earth threatening asteroid using gravity as a towline. The
spacecraft hovers near the asteroid with thrusters angled outward so the
exhaust does not impinge on the surface. This deflection method is insensitive
to the structure, surface properties, and rotation state of the asteroid.


title:
Oscillations of rotating bodies: A self-adjoint formalism applied to
  dynamic tides and tidal capture

abstract:
  We consider the excitation of the inertial modes of a uniformly rotating
fully convective body due to a close encounter with another object. This could
lead to a tidal capture or orbital circularisation depending on whether the
initial orbit is unbound or highly eccentric. We develop a general self-adjoint
formalism for the response problem and thus solve it taking into account the
inertial modes with $m=2$ for a full polytrope with $n=1.5.$ We are accordingly
able to show in this case that the excitation of inertial modes dominates the
response for large impact parameters and thus cannot be neglected in
calculations of tidal energy and angular momentum exchange or orbital
circularisation from large eccentricity.


title:
Acceptance of fluorescence detectors and its implication in energy
  spectrum inference at the highest energies

abstract:
  Along the years HiRes and AGASA experiments have explored the fluorescence
and the ground array experimental techniques to measure extensive air showers,
being both essential to investigate the ultra-high energy cosmic rays. However,
such Collaborations have published contradictory energy spectra for energies
above the GZK cut-off. In this article, we investigate the acceptance of
fluorescence telescopes to different primary particles at the highest energies.
Using CORSIKA and CONEX shower simulations without and with the new
pre-showering scheme, which allows photons to interact in the Earth magnetic
field, we estimate the aperture of the HiRes-I telescope for gammas, iron
nuclei and protons primaries as a function of the number of simulated events
and primary energy. We also investigate the possibility that systematic
differences in shower development for hadrons and gammas could mask or distort
vital features of the cosmic ray energy spectrum at energies above the
photo-pion production threshold. The impact of these effects on the true
acceptance of a fluorescence detector is analyzed in the context of top-down
production models.


title: The effect of low mass substructures on the Cusp lensing relation

abstract:
  It has been argued that the flux anomalies detected in gravitationally lensed
QSOs are evidence for substructures in the foreground lensing haloes. In this
paper we investigate this issue in greater detail focusing on the Cusp relation
which corresponds to images of a source located to the cusp of the inner
caustic curve. We use numerical simulations combined with a Monte Carlo
approach to study the effects of the expected power law distribution of
substructures within LCDM haloes on the multiple images.
  Generally, the high number of anomalous flux ratios in the cusp
configurations is unlikely explained by 'simple' perturbers (subhaloes) inside
the lensing galaxy, either modeled by point masses or extended NFW subhaloes.
We considered in our analysis a mass range of 10^5-10^7 Msun for the subhaloes.
We also demonstrate that including the effects of the surrounding mass
distribution, such as other galaxies close to the primary lens, does not change
the results. We conclude that triple images of lensed QSOs do not show any
direct evidence for dark dwarf galaxies such as cold dark matter substructure.


title:
A Fundamental Plane Relation for the X-Ray Gas in Normal Elliptical
  Galaxies

abstract:
  We report on the discovery of a new correlation between global parameters of
the hot interstellar gas in elliptical galaxies. We reanalyze archival Chandra
data for 30 normal early-type systems, removing the contributions of resolved
and unresolved point sources to reveal the X-ray morphology of the hot gas. We
determine the half-light radius, R_X, and the mean surface brightness, I_X,
from the gas surface brightness profiles. A spectral analysis determines the
temperature, T_X, of the gas within 3 optical effective radii. We find that the
galaxies lie on an X-ray Gas Fundamental Plane (XGFP) of the form T_X ~
R_X^{0.28} I_X^{0.22}. This is close to, but distinct from, a simple
luminosity-temperature relation. The intrinsic width of the XGFP is only
0.07dex, nearly identical to that of the stellar (optical) fundamental plane
(SFP). This is surprising since X-ray gas masses are typically ~10^{-2} of the
stellar masses. We show that the XGFP is not a simple consequence of the virial
theorem or hydrostatic equilibrium, and that it is essentially independent of
the SFP. The XGFP thus represents a genuinely new constraint on the
hydrodynamical evolution of elliptical galaxies.


title: ZEN and the search for high-redshift galaxies

abstract:
  We present the ZEN (z equals nine) survey: a deep, narrow J-band search for
proto-galactic Lya emission at redshifts z=9. In the first phase of the survey,
dubbed ZEN1, we combine an exceptionally deep image of the Hubble Deep Field
South, obtained using a narrow band filter centred on the wavelength 1.187
microns, with existing deep, broad band images covering optical to near
infrared wavelengths. Candidate z=9 Lya-emitting galaxies display a significant
narrow band excess relative to the Js-band that are undetected at optical
wavelengths. We detect no sources consistent with this criterion to the 90%
point source flux limit of the NB image, F_NB = 3.28e-18 ergs/s/cm2. The survey
selection function indicates that we have sampled a volume of approximately 340
h^{-3} Mpc3 to a Lya emission luminosity of 10e43 h^{-2} ergs/s. When compared
to the predicted properties of z=9 galaxies based upon no evolution of observed
z=6 Lya-emitting galaxies, the `volume shortfall' of the current survey, i.e.
the volume required to detect this putative population, is a factor of at least
8 to 10. We also discuss continuing narrow J-band imaging surveys that will
reduce the volume shortfall factor to the point where the no-evolution
prediction from z=6 is probed in a meaningful manner.


title: 3-D GRMHD Simulations of Disk-Jet Coupling and Emission

abstract:
  We have performed a fully three-dimensional general relativistic
magnetohydrodynamic (GRMHD) simulation of jet formation from a thin accretion
disk around a Schwarzschild black hole with a free-falling corona. The initial
simulation results show that a bipolar jet (velocity nearly 0.3c) is created as
shown by previous two-dimensional axisymmetric simulations with mirror symmetry
at the equator. The 3-D simulation ran over one hundred light-crossing time
units which is considerably longer than the previous simulations. We show that
the jet is initially formed as predicted due in part to magnetic pressure from
the twisting the initially uniform magnetic field and from gas pressure
associated with shock formation in the region around r = 3r_S. At later times,
the accretion disk becomes thick and the jet fades resulting in a wind that is
ejected from the surface of the thickened (torus-like) disk. It should be noted
that no streaming matter from a donor is included at the outer boundary in the
simulation (an isolated black hole not binary black hole). The wind flows
outwards with a wider angle than the initial jet. The widening of the jet is
consistent with the outward moving torsional Alfven waves (TAWs). This
evolution of disk-jet coupling suggests that the jet fades with a thickened
accretion disk due to the lack of streaming material from an accompanying star.


title: Photometric entropy of stellar populations and related diagnostic tools

abstract:
  We discuss, from a statistical point of view, some leading issues that deal
with the study of stellar populations in fully or partially unresolved
aggregates, like globular clusters and distant galaxies. A confident assessment
of the effective number and luminosity of stellar contributors can provide, in
this regard, a very useful interpretative tool to properly assess the
observational bias coming from crowding conditions or surface brightness
fluctuations. These arguments have led us to introduce a new concept of
"photometric entropy" of a stellar population, whose impact on different
astrophysical aspects of cluster diagnostic has been reviewed here.


title: Particle acceleration in electron-ion jets

abstract:
  Weibel instability created in collisionless shocks is responsible for
particle (electron, positron, and ion) acceleration. Using a 3-D relativistic
electromagnetic particle (REMP) code, we have investigated particle
acceleration associated with a relativistic electron-ion jet fronts propagating
into an ambient plasma without initial magnetic fields with a longer simulation
system in order to investigate nonlinear stage of the Weibel instability and
its acceleration mechanism. The current channels generated by the Weibel
instability induce the radial electric fields. The z component of the Poynting
vector (E x B) become positive in the large region along the jet propagation
direction. This leads to the acceleration of jet electrons along the jet. In
particular the E x B drift with the large scale current channel generated by
the ion Weibel instability accelerate electrons effectively in both parallel
and perpendicular directions.