title:
The "K-Correction" for Irradiated Emission Lines in LMXBs: Evidence for
  a Massive Neutron Star in X1822-371 (V691 CrA)

abstract:
  We study the K-correction for the case of emission lines formed in the X-ray
illuminated atmosphere of a Roche lobe filling star. We compute the
K-correction as function of the mass ratio 'q' and the disc flaring angle
'alpha' using a compact binary code where the companion's Roche lobe is divided
into 10^5 resolution elements. We also study the effect of the inclination
angle in the results. We apply our model to the case of the neutron star
low-mass X-ray binary X1822-371 (V691 CrA), where a K-emission velocity
K_em=300 +-8 km/s has been measured by Casares et al. (2003). Our numerical
results, combined with previous determination of system parameters, yields
1.61Msun < M_NS < 2.32Msun and 0.44Msun < M_2 < 0.56Msun for the two binary
components(i. e. 0.24 < q < 0.27), which provide a compelling evidence for a
massive neutron star in this system. We also discuss the implications of these
masses into the evolutionary history of the binary.


title:
Intracluster Planetary Nebulae as dynamical probes of the diffuse light
  in galaxy clusters

abstract:
  I will review the latest results for the presence of diffuse light in the
nearby universe and at intermediate redshift, and then discuss the latest
results from hydrodynamical cosmological simulations of cluster formation on
the expected properties of diffuse light in clusters. I shall present how
intracluster planetary nebulae (ICPNe) can be used as excellent tracers of the
diffuse stellar population in nearby clusters, and how their number density
profile and radial velocity distribution can provide an observational test for
models of cluster formation. The preliminary comparison of available ICPN
samples with predictions from cosmological simulations support late infall as
the most likely mechanism for the origin of diffuse stellar light in clusters.


title: Dust properties of UV bright galaxies at z ~ 2

abstract:
  We investigate the properties of the extinction curve in the rest-frame UV
for a sample of 34 UV-luminous galaxies at 2 < z < 2.5, selected from the FORS
Deep Field (FDF) spectroscopic survey. A new parametric description of the
rest-frame UV spectral energy distribution is adopted; its sensitivity to
properties of the stellar populations or of dust attenuation is established
with the use of combined stellar population and radiative transfer models. The
distribution of the z ~ 2 UV-luminous FDF galaxies in several diagnostic
diagrams shows that their extinction curves range between those typical of the
Small and Large Magellanic Clouds (SMC and LMC, respectively). For the majority
of strongly reddened objects having a UV continuum slope beta > -0.4 a
significant 2175 A absorption feature is inferred, indicating an LMC-like
extinction curve. On the other hand, the UV continua of the least reddened
objects are mostly consistent with SMC-like extinction curves, lacking a
significant 2175 A bump, as for the Calzetti et al. sample of local starbursts.
Furthermore, the most opaque (beta ~ 0) UV-luminous galaxies tend to be among
the most metal rich, most massive, and largest systems at z ~ 2. The presence
of the UV bump does not seem to depend on the total metallicity, as given by
the equivalent width (EW) of the C IV doublet. Conversely, it seems to be
associated with large EWs of prominent interstellar low-ionisation absorption
lines, suggesting a link between the strength of the UV bump and the topology
of the interstellar medium of the most evolved UV-luminous, massive galaxies at
z ~ 2.


title:
Photometry of neglected open clusters in the First and Fourth Galactic
  Quadrants

abstract:
  CCD $BVI$ photometry is presented for 8 previously unstudied star clusters
located in the First and Fourth Galactic Quadrants: AL~1, BH 150, NGC 5764,
Lynga~9, Czernik~37, BH 261, Berkeley~80 and King~25. Color magnitude diagrams
of the cluster regions suggest that several of them (BH 150, Lynga~9,
Czernik~37 and BH 261 and King~25) are so embedded in the dense stellar
population toward the galactic center that their properties, or even their
existence as physical systems, cannot be confirmed. Lynga~9, BH 261 and King~25
appear to be slight enhancements of dense star fields, BH 150 is probably just
a single bright star in a dense field, and Czernik~37 may be a sparse, but real
cluster superimposed on the galactic bulge population. We derive preliminary
estimates of the physical parameters for the remaining clusters. AL~1 appears
to be an intermediate age cluster beyond the solar circle on the far side of
the galaxy and the final two clusters, NGC 5764 and Berkeley 80 are also of
intermediate age but located inside the solar ring. This set of clusters
highlights the difficulties inherent in studying the stellar populations toward
the inner regions of the galaxy.


title:
A 3-5$\mu$m VLT spectroscopic survey of embedded young low mass stars
  II; OCN$^-$

abstract:
  The 4.62$\mu$m (2164.5 cm$^{-1}$) `XCN' band has been detected in the
$M$-band spectra of 34 deeply embedded young stellar objects (YSO's), observed
with high signal-to-noise and high spectral resolution with the VLT-ISAAC
spectrometer, providing the first opportunity to study the solid OCN$^-$
abundance toward a large number of low-mass YSO's. It is shown unequivocally
that at least two components, centred at 2165.7 cm$^{-1}$ (FWHM = 26 cm$^{-1}$)
and 2175.4 cm$^{-1}$ (FWHM = 15 cm$^{-1}$), underlie the XCN band. Only the
2165.7-component can be ascribed to OCN$^-$, embedded in a strongly
hydrogen-bonding, and possibly thermally annealed, ice environment based on
laboratory OCN$^-$ spectra. In order to correct for the contribution of the
2175.4-component to the XCN band, a phenomenological decomposition into the
2165.7- and the 2175.4-components is used to fit the full band profile and
derive the OCN$^-$ abundance for each line-of-sight. The same analysis is
performed for 5 high-mass YSO's taken from the ISO-SWS data archive. Inferred
OCN$^-$ abundances are $\leq$ 0.85 % toward low-mass YSO's and $\leq$ 1 %
toward high-mass YSO's, except for W33 A. Abundances are found to vary by at
least a factor of 10--20 and large source-to-source abundance variations are
observed within the same star-forming cloud complex on scales down to 400 AU,
indicating that the OCN$^-$ formation mechanism is sensitive to local
conditions. The inferred abundances allow quantitatively for photochemical
formation of OCN$^-$, but the large abundance variations are not easily
explained in this scenario unless local radiation sources or special geometries
are invoked. Surface chemistry should therefore be considered as an alternative
formation mechanism.


title: Asymmetric Drift and the Stellar Velocity Ellipsoid

abstract:
  We present the decomposition of the stellar velocity ellipsoid using stellar
velocity dispersions within a 40 deg wedge about the major-axis (sigma_maj),
the epicycle approximation, and the asymmetric drift equation. Thus, we employ
no fitted forms for sigma_maj and escape interpolation errors resulting from
comparisons of the major and minor axes. We apply the theoretical construction
of the method to integral field data taken for NGC 3949 and NGC 3982. We derive
the vertical-to-radial velocity dispersion ratio (sigma_z / sigma_R) and find
(1) our decomposition method is accurate and reasonable, (2) NGC 3982 appears
to be rather typical of an Sb type galaxy with sigma_z / sigma_R = 0.73
(+0.13/-0.11) despite its high surface brightness and small size, and (3) NGC
3949 has a hot disk with sigma_z / sigma_R = 1.18 (+0.36/-0.28).


title: Small scale WIMP physics

abstract:
  The dark matter distribution on small scales may depend on the the properties
of the first generation of dark matter halos to form, which is in turn
determined by the microphysics of the dark matter particles. We overview the
microphysics of WIMPs and our calculations of the collisional damping and free
streaming scales. We then plot the resulting density perturbation power
spectrum and red-shift at which typical halos form, taking into account the
effect of uncertainties in the WIMP properties (mass and interaction channel)
and the primordial power spectrum. Finally we review recent developments
regarding the properties and fate of the first WIMPy halos.


title: Hectospec, the MMT's 300 Optical Fiber-Fed Spectrograph

abstract:
  The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT
in the spring of 2004. A pair of high-speed six-axis robots move the 300 fiber
buttons between observing configurations within ~300 s and to an accuracy ~25
microns. The optical fibers run for 26 m between the MMT's focal surface and
the bench spectrograph operating at R~1000-2000. Another high dispersion bench
spectrograph offering R~5,000, Hectochelle, is also available. The system
throughput, including all losses in the telescope optics, fibers, and
spectrograph peaks at ~10% at the grating blaze in 1" FWHM seeing. Correcting
for aperture losses at the 1.5" diameter fiber entrance aperture, the system
throughput peaks at $\sim$17%. Hectospec has proven to be a workhorse
instrument at the MMT. Hectospec and Hectochelle together were scheduled for
1/3 of the available nights since its commissioning. Hectospec has returned
\~60,000 reduced spectra for 16 scientific programs during its first year of
operation.


title: Constraining the Distribution of L- & T-Dwarfs in the Galaxy

abstract:
  We estimate the thin disk scale height of the Galactic population of L- &
T-dwarfs based on star counts from 15 deep parallel fields from the Hubble
Space Telescope. From these observations, we have identified 28 candidate L- &
T- dwarfs based on their (i'-z') color and morphology. By comparing these star
counts to a simple Galactic model, we estimate the scale height to be 350+-50
pc that is consistent with the increase in vertical scale with decreasing
stellar mass and is independent of reddening, color-magnitude limits, and other
Galactic parameters. With this refined measure, we predict that less than 10^9
M_{sol} of the Milky Way can be in the form L- & T- dwarfs, and confirm that
high-latitude, z~6 galaxy surveys which use the i'-band dropout technique are
97-100% free of L- & T- dwarf interlopers.


title:
Resonant amplification of magnetic seed fields by gravitational waves in
  the early universe

abstract:
  Inflation is known to produce both gravitational waves and seed magnetic
fields on scales well beyond the size of the horizon. The general relativistic
interaction between these two sources at the end of inflation showed a
significant amplification of the initial magnetic seed, which brought the
latter within the currently accepted dynamo limits. In the present article we
revisit this gravito-magnetic interaction and argue that the observed strong
growth of the field is the result of resonance. More specifically, we show that
the maximum magnetic boost always occurs when the wavelength of the inducing
gravitational radiation and the scale of the original seed field coincide. We
also look closer at the physics of the proposed Maxwell-Weyl coupling, consider
the implications of finite electrical conductivity for the efficiency of the
amplification mechanism and clarify further the mathematics of the analysis.


title:
On the X-ray Properties of OH Megamaser Sources: Chandra Snapshot
  Observations

abstract:
  We present Chandra snapshot observations for a sample of 7 sources selected
from the Arecibo OH megamaser (OHM) survey at z~0.13-0.22 and with far-infrared
luminosities in excess of 10^{11} L_sun. In contrast with the known H2O
megamasers, which are mostly associated with powerful Active Galactic Nuclei
(AGN), the situation is far less clear for OHMs, which have been poorly studied
in the X-ray band thus far. All of the observed sources are X-ray weak, with
only one OHM, IRAS FSC 03521+0028 (z=0.15), being detected by Chandra (with 5
counts). The results from this pilot program indicate that the X-ray emission,
with luminosities of less than ~10^{42} erg/s, is consistent with that from
star formation (as also suggested in some cases by the optical spectra) and
low-luminosity AGN emission. If an AGN is present, its contribution to the
broad-band emission of OHM galaxies is likely modest. Under reasonable
assumptions about the intrinsic X-ray spectral shape, the observed count
distribution from stacking analysis suggests absorption of ~10^{22} cm^{-2}.


title:
The Number Density of Intermediate and High Luminosity Active Galactic
  Nuclei at z~2-3

abstract:
  We use the combination of the 2 Ms Chandra X-ray image, new J and H band
images, and the Spitzer IRAC and MIPS images of the Chandra Deep Field-North to
obtain high spectroscopic and photometric redshift completeness of high and
intermediate X-ray luminosity sources in the redshift interval z=2-3. We
measure the number densities of z=2-3 active galactic nuclei (AGNs) and
broad-line AGNs in the rest-frame 2-8 keV luminosity intervals 10^44-10^45 and
10^43-10^44 ergs/s and compare with previous lower redshift results. We confirm
a decline in the number densities of intermediate-luminosity sources at z>1. We
also measure the number density of z=2-3 AGNs in the luminosity interval
10^43-10^44.5 ergs/s and compare with previous low and high-redshift results.
Again, we find a decline in the number densities at z>1. In both cases, we can
rule out the hypothesis that the number densities remain flat to z=2-3 at above
the 5-sigma level.


title: SparsePak Observations of Diffuse Ionized Gas Halo Kinematics in NGC 891

abstract:
  We present WIYN SparsePak observations of the diffuse ionized gas (DIG) halo
of NGC 891. Preliminary results of an analysis of the halo velocity field
reveal a clear gradient of the azimuthal velocity with z which agrees with
results for the neutral gas. The magnitude of the gradient has been determined,
using two independent methods, to be approximately 15 km/s/kpc.


title: Gravity Waves in the Sun

abstract:
  We present numerical simulations of penetrative convection and gravity wave
excitation in the Sun. Gravity waves are self-consistently generated by a
convective zone overlying a radiative interior. We produce power spectra for
gravity waves in the radiative region as well as estimates for the energy flux
of gravity waves below the convection zone. We calculate a peak energy flux in
waves below the convection zone to be three orders of magnitude smaller than
previous estimates for m=1. The simulations show that the linear dispersion
relation is a good approximation only deep below the convective-radiative
boundary. Both low frequency propagating gravity waves as well as higher
frequency standing modes are generated; although we find that convection does
not continually drive the standing g-mode frequencies.


title:
Keck Interferometer observations of classical and weak line T Tauri
  stars

abstract:
  We present observations of the T Tauri stars BP Tau, DG Tau, DI Tau, GM Aur,
LkCa 15, RW Aur and V830 Tau, using long baseline infrared interferometry at K
band (2.2 microns) from the Keck Interferometer. The target sources have a
range of mass accretion rates and excess near-infrared emission. The
interferometer is most sensitive to extended emission on characteristic size
scales of 1 to 5 millarcseconds. All sources show evidence for resolved K band
emission on these scales, although a few of the sources are marginally
consistent with being unresolved. We calculate the infrared excess based on
fitting stellar photosphere models to the optical photometry and estimate the
physical size of the emission region using simple geometric models for the
sources with a significant infrared excess. Assuming that the K band resolved
emission traces the inner edge of the dust disk, we compare the measured
characteristic sizes to predicted dust sublimation radii and find that the
models require a range of dust sublimation temperatures and possibly optical
depths within the inner rim to match the measured radii.


title:
The Formation of Star Clusters II: 3D Simulations of Magnetohydrodynamic
  Turbulence in Molecular Clouds

abstract:
  (Abridged) We present a series of decaying turbulence simulations that
represent a cluster-forming clump within a molecular cloud, investigating the
role of magnetic fields on the formation of potential star-forming cores. We
present an exhaustive analysis of numerical data from these simulations that
includes a compilation of all of the distributions of physical properties that
characterize bound cores - including their masses, radii, mean densities,
angular momenta, spins, magnetizations, and mass-to-flux ratios. We also
present line maps of our models that can be compared with observations. Our
simulations range between 5-30 Jeans masses of gas, and are representative of
molecular cloud clumps with masses between 100-1000 solar masses. The cores
have mass-to-flux ratios that are generally less than that of the original
cloud, and so a cloud that is initially highly supercritical can produce cores
that are slightly supercritical, similar to that seen by Zeeman measurements of
molecular cloud cores. Clouds that are initially only slightly supercritical
will instead collapse along the field lines into sheets, and the cores that
form as these sheets fragment have a different mass spectrum than what is
observed. The spin rates of these cores suggests that subsequent fragmentation
into multiple systems is likely. The sizes of the bound cores that are produced
are typically 0.02-0.2 pc and have densities in the range 10^4-10^5 cm^{-3} in
agreement with observational surveys. Finally, our numerical data allow us to
test theoretical models of the mass spectrum of cores, such as the turbulent
fragmentation picture of Padoan-Nordlund. We find that while this model gets
the shape of the core mass spectrum reasonably well, it fails to predict the
peak mass in the core mass spectrum.


title: A Fluctuation Analysis of the Bolocam 1.1mm Lockman Hole Survey

abstract:
  We perform a fluctuation analysis of the 1.1mm Bolocam Lockman Hole Survey,
which covers 324 square arcmin to a very uniform point source-filtered RMS
noise level of 1.4 mJy/beam. The fluctuation analysis has the significant
advantage of utilizing all of the available data. We constrain the number
counts in the 1-10 mJy range, and derive significantly tighter constraints than
in previous work: the power-law index is 2.7 (+0.18, -0.15), while the
amplitude is equal to 1595 (+85,-238) sources per mJy per square degree, or
N(>1 mJy) = 940 (+50,-140) sources/square degree (95% confidence). Our results
agree extremely well with those derived from the extracted source number counts
by Laurent et al (2005). Our derived normalization is about 2.5 times smaller
than determined by MAMBO at 1.2mm by Greve et al (2004). However, the
uncertainty in the normalization for both data sets is dominated by the
systematic (i.e., absolute flux calibration) rather than statistical errors;
within these uncertainties, our results are in agreement. We estimate that
about 7% of the 1.1mm background has been resolved at 1 mJy.


title:
Photometric Covariance in Multi-Band Surveys: Understanding the
  Photometric Error in the SDSS

abstract:
  In this paper we describe a detailed analysis of the photometric
uncertainties present within the Sloan Digital Sky Survey (SDSS) imaging survey
based on repeat observations of approximately 200 square degrees of the sky. We
show that, for the standard SDSS aperture systems (petrocounts, counts_model,
psfcounts and cmodel_counts), the errors generated by the SDSS photometric
pipeline under-estimate the observed scatter in the individual bands. The
degree of disagreement is a strong function of aperture and magnitude (ranging
from 20% to more than a factor of 2). We also find that the photometry in the
five optical bands can be highly correlated for both point sources and
galaxies, although the correlation for point sources is almost entirely due to
variable objects. Without correcting for this covariance the SDSS color errors
could be in over-estimated by a factor of two to three. Combining these
opposing effects, the SDSS errors on the colors differ from the observed color
variation by approximately 10-20% for most apertures and magnitudes. We provide
a prescription to correct the errors derived from the SDSS photometric pipeline
as a function of magnitude and a semi-analytic method for generating the
appropriate covariance between the different photometric passbands. Given the
intrinsic nature of these correlations, we expect that all current and future
multi-band surveys will also observe strongly covariant magnitudes. The ability
of these surveys to complete their science goals is largely dependent on
color-based target selection and photometric redshifts; these results show the
importance of spending a significant fraction of early survey operations on
re-imaging to empirically determine the photometric covariance of any
observing/reduction pipeline.


title:
The impact of accurate distances to dwarf elliptical galaxies on
  cosmology

abstract:
  The Surface Brightness Fluctuation method has been shown to be a powerful
distance indicator for dwarf elliptical galaxies to very low surface brightness
levels. It is applicable to stellar systems that are out of reach for classical
indicators requiring resolved stellar populations such as the tip magnitude of
the red giant branch. I briefly discuss a few results from recent SBF studies
of dEs to demonstrate the significance of the SBF method to address
long-standing issues related to cosmography, dark matter in galaxy groups,
substructures in clusters, and the discrepancy between the mass function of
collapsed objects and the faint end of the galaxy luminosity function. For the
analysis of the large number of galaxy images that need to be processed as part
of such SBF studies we are currently developing a fast, semi-automatic
reduction pipeline that will be made readily available to the astronomical
community.


title:
Electrodynamics in Friedmann-Robertson-Walker Universe: Maxwell and
  Dirac fields in Newman-Penrose formalism

abstract:
  Maxwell and Dirac fields in Friedmann-Robertson-Walker spacetime is
investigated using the Newman-Penrose method. The variables are all separable,
with the angular dependence given by the spin-weighted spherical harmonics. All
the radial parts reduce to the barrier penetration problem, with mostly
repulsive potentials representing the centrifugal energies. Both the helicity
states of the photon field see the same potential, but that of the Dirac field
see different ones; one component even sees attractive potential in the open
universe. The massless fields have the usual exponential time dependencies;
that of the massive Dirac field is coupled to the evolution of the cosmic scale
factor $a$. The case of the radiation filled flat universe is solved in terms
of the Whittaker function. A formal series solution, valid in any FRW universe,
is also presented. The energy density of the Maxwell field is explicitly shown
to scale as $a^{-4}$. The co-moving particle number density of the massless
Dirac field is found to be conserved, but that of the massive one is not.
Particles flow out of certain regions, and into others, creating regions that
are depleted of certain linear and angular momenta states, and others with
excess. Such current of charged particles would constitute an electric current
that could generate a cosmic magnetic field. In contrast, the energy density of
these massive particles still scales as $a^{-4}$.


title: Damping of MHD turbulence in Solar Flares

abstract:
  (Abridged) We describe the cascade of plasma waves or turbulence injected,
presumably by reconnection, at scales comparable to the size of a solar flare
loop to scales comparable to particle gyroradii, and evaluate their damping by
various mechanisms. We show that the classical viscous damping is unimportant
for magnetically dominated or low beta plasmas and the primary damping
mechanism is the collisionless damping by the background particles. We show
that the damping rate is proportional to the total random momentum density of
the particles. For solar flare conditions this means that in most flares,
except the very large ones, the damping is dominated by thermal background
electrons. For large flares one requires acceleration of essentially all
background electrons into a nonthermal distribution so that the accelerated
electrons can be important in the damping of the waves. In general, damping by
thermal or nonthermal protons is negligible compared to that of electrons
except for quasi-perpendicular propagating waves or for rare proton dominated
flares with strong nuclear gamma-ray line emission. Using the rate for damping
we determine the critical scale below which the damping becomes important and
the spectrum of the turbulence steepens. This critical scale, however, has
strong dependence on the angle of propagation with respect to the magnetic
field direction. The waves can cascade down to very small scales, such as the
gyroradii of the particles at small angles (quasi-parallel propagation) and
possibly near 90 degree (quasi-perpendicular propagation) giving rise to a
highly anisotropic spectral distribution.


title:
Successful Coronal Heating and Solar Wind Acceleration by MHD Waves by
  Numerical Simulations from Photosphere to 0.3AU

abstract:
  We show that the coronal heating and the acceleration of the fast solar wind
in the coronal holes are natural consequence of the footpoint fluctuations of
the magnetic fields at the photosphere by one-dimensional, time-dependent, and
nonlinear magnetohydrodynamical simulation with radiative cooling and thermal
conduction. We impose low-frequency (<0.05Hz) transverse photospheric motions,
corresponding to the granulations, with velocity <dv> = 0.7$km/s. In spite of
the attenuation in the chromosphere by the reflection, the sufficient energy of
the generated outgoing Alfven waves transmit into the corona to heat and
accelerate of the plasma by nonlinear dissipation. Our result clearly shows
that the initial cool (10^4K) and static atmosphere is naturally heated up to
10^6K and accelerated to 800km/s, and explain recent SoHO observations and
Interplanetary Scintillation measurements.


title:
Spitzer IRAC Imaging of the Relativistic Jet from Superluminal Quasar
  PKS 0637-752

abstract:
  Emission from the relativistic jet located at hundreds of kpc from the core
of the superluminal quasar PKS 0637-752 was detected at 3.6 and 5.8 microns
with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. The
unprecedented sensitivity and arcsecond resolution of IRAC allows us to explore
the mid-infrared emission from kiloparsec-scale quasar jets for the first time.
The mid-infrared flux from the jet knots, when combined with radio and optical
fluxes, confirms a synchrotron origin of the radio-to-optical emission and
constrains very well the high energy end of the nonthermal electron
distribution. Assuming the X-rays are produced in the relativistically moving
knots via inverse Compton scattering of cosmic microwave background (CMB)
radiation, the infrared observation puts constraints on the matter content of
the quasar extended jet. Specifically, pure electron-positoron pair jet models
are unfavorable based on the lack of an infrared bump associated with ``bulk
Comptonization'' of CMB photons by an ultrarelativistic jet.


title: The blueshift of the [O III] emission line in NLS1s

abstract:
  We investigate the radial velocity difference between the narrow
emission-line components of [O III] $\lambda$ 5007 and H$\beta$ in a sample of
150 SDSS NLS1s. Seven "blue outliers" with [O III] blueshifted by more than 250
\kms are found. A strong correlation between the [O III] blueshift and the
Eddington ratio is found for these seven "blue outliers". For the entire
sample, we found a modest correlation between the blueshift and the linewidth
of the narrow component of the [O III] line. The reflected profile of [O III]
indicates two kinematically and physically distinct regions. The [O III]
linewidth depends not only on the bulge stellar gravitational potential, but
also on the central black hole potential.


title: CH 3 GHz Observations of Molecular Clouds Along the Galactic Plane

abstract:
  Spectra in the CH $^2\Pi_{1/2}$, J=1/2, F=1-1 transition at 3335 MHz were
obtained in three 5-point crosses centered on the Galactic plane at $\ell =$
50$\arcdeg$, 100$\arcdeg$, and 110$\arcdeg$. The lines of sight traverse both
Giant Molecular Clouds (GMCs) and local, smaller entities. This transition is a
good tracer of low-density molecular gas and the line profiles are very similar
to CO(1-0) data at nearly the same resolution. In addition, the CH 3335 MHz
line can be used to calibrate the CO-H$_2$ conversion factor (X$_{\rm CO}$) in
low-density molecular gas. Although this technique underestimates X$_{\rm CO}$
in GMCs, our results are within a factor of two of X$_{\rm CO}$ values
calibrated for GMCs by other techniques. The similarity of CH and CO line
profiles, and that of X$_{\rm CO}$ values derived from CH and more traditional
techniques, implies that most of the molecular gas along the observed lines of
sight is at relatively low densities ($n \le$ 10$^3$ cm$^{-3}$).


title: Observational Evidence for Extra Dimensions from Dark Matter

abstract:
  Recent astronomical observations of systems of dark matter, which have been
cited as providing possible support for self-interacting cold dark matter, may
provide evidence for the extra dimensions predicted by superstring scenarios.
We find that the properties of the required dark matter self-interaction are
precisely the consequences of a world with 3 large extra dimensions of size
\~1nm, where gravity follows the r^{-5} law at scales below ~1nm. From the
cross sections measured for various dark matter systems, we also constrain the
mass of dark matter particles to be m_x ~ 3*10^{-16} proton mass, consistent
with the mass of axions.


title: Non-Gaussianity in Curvaton Models with Nearly Quadratic Potential

abstract:
  We consider curvaton models with potentials that depart slightly from the
quadratic form. We show that although such a small departure does not modify
significantly the Gaussian part of the curvature perturbation, it can have a
pronounced effect on the level of non-Gaussianity. We find that unlike in the
quadratic case, the limit of small non-Gaussianity, $|f_{NL}|\ll1$, is quite
possible even with small curvaton energy density $r\ll1$ . Furthermore,
non-Gaussianity does not imply any strict bounds on $r$ but the bounds depend
on the assumptions about the higher order terms in the curvaton potential.


title:
The X-ray emission lines in GRB afterglows: the evidence for the
  two-component jet model

abstract:
  Recently, X-ray emission lines have been observed in X-ray afterglows of
several $\gamma$-ray bursts. It is a major breakthrough for understanding the
nature of the progenitors. It is proposed that the X-ray emission lines can be
well explained by the Geometry-Dominated models, but in these models the
illuminating angle is much larger than that of the collimated jet of the
$\gamma$-ray bursts(GRBs). For GRB 011211, we obtain the illuminating angle is
about $\theta\sim45^{\circ}$, while the angle of GRB jet is only $3.6^{\circ}$,
so we propose that the outflow of the GRBs with emission lines should have two
distinct components. The wide component illuminates the reprocessing material,
and produces the emission lines, while the narrow one produces the $\gamma$-ray
bursts. The observations show that the energy for producing the emission lines
is higher than that of the GRBs. In this case, when the wide component
dominates the afterglows, a bump will appear in the GRBs afterglows. For GRB
011211, the emergence time of the bump is less than 0.05 days after the GRB, it
is obviously too early for the observation to catch it. With the presence of
the X-ray emission lines there should also be a bright emission component
between the UV and the soft X-rays. These features can be tested by the $Swift$
satellite in the near future.


title: Revisiting the population of Galactic open clusters

abstract:
  We present results of a study of the galactic open cluster population based
on the all-sky catalogue ASCC-2.5 (I/280A) compiled from Tycho-2, Hipparcos and
other catalogues. The sample of optical clusters from ASCC-2.5 is complete up
to about 850 pc from the Sun. The symmetry plane of the clusters' distribution
is determined to be at $Z_0=-22\pm4$ pc, and the scale height of open clusters
is only $56\pm3$ pc. The total surface density and volume density in the
symmetry plane are $\Sigma=$ 114 kpc$^{-2}$ and $D(Z_0)=1015$ kpc$^{-3}$,
respectively. We find the total number of open clusters in the Galactic disk to
be of order of 10$^5$ at present. Fluctuations in the spatial and velocity
distributions are attributed to the existence of four open cluster complexes
(OCCs) of different ages containing up to a few tens of clusters. Members in an
OCC show the same kinematic behaviour, and a narrow age spread. We find, that
the youngest cluster complex, OCC~1 ($\log t<7.9$), with 19 deg inclination to
the Galactic plane, is apparently a signature of Gould's Belt. The most
abundant OCC~2 complex has moderate age ($\log t\approx8.45$). The clusters of
the Perseus-Auriga group, having the same age as OCC~2, but different
kinematics are seen in breaks between Perseus-Auriga clouds. The oldest ($\log
t\approx8.85$) and sparsest group was identified due to a large motion in the
Galactic anticentre direction. Formation rate and lifetime of open clusters are
found to be $0.23\pm0.03$ kpc$^{-2}$Myr$^{-1}$ and 322$\pm$31 Myr,
respectively. This implies a total number of cluster generations in the history
of the Galaxy between 30 to 40. We estimate that less than about 10% of the
total Galactic stellar disk population has ever passed an open cluster
membership.


title:
Reconstruction of the quasar brightness profile from observations of
  high magnification events

abstract:
  The analysis of the high magnification events in the A and C components of
the quadruple gravitational lens QSO2237+0305 observed by OGLE and GLITP
collaborations in V band was carried out. The significant light amplifications
of the components are interpreted as the effect of microlensing with a fold
caustic. For the reconstruction of the one-dimensional source profile the
technique based on Tikhonov regularization method was used. The estimates of
the effective radius of the quasar's emitting region (the radius within which
half of the light is emitted) based on reconstructed profile of the source from
microlensing of the A and C components are in the range of 31 and 21 days and
correspond to the linear sizes 0.62e+15 cm and 0.42e+15 cm. For the A component
the positive crossing of the caustic and for the C component the negative
crossing of the caustic was confirmed.


title:
Binarity, activity and metallicity among late-type stars I. Methodology
  and application to HD 27536 and HD 216803

abstract:
  We present the first in a series of papers that attempt to investigate the
relation between binarity, magnetic activity, and chemical surface abundances
of cool stars. In the current paper, we lay out and test two abundance analysis
methods and apply them to two well-known, active, single stars, HD 27536
(G8IV-III) and HD 216803 (K5V), presenting photospheric fundamental parameters
and abundances of Li, Al, Ca, Si, Sc, Ti, V, Cr, Fe, Co and Ni. The abundances
from the two methods agree within the errors for all elements except calcium in
\hdeen, which means that either method yields the same fundamental model
parameters and the same abundances. Activity is described by the radiative loss
in the Ca II H & K lines with respect to the bolometric luminosity, through the
activity index R_{HK}. Binarity is established by very precise radial velocity
(RV) measurements using HARPS spectra. The spectral line bisectors are examined
for correlations between RV and bisector shape to distinguish between the
effects of stellar activity and unseen companions. We show that HD 27536
exhibit RV variations mimicking the effect of a low-mass (m ~ 4M_J) companion
in a relatively close (a ~ 1AU) orbit. The variation is strongly correlated
with the activity, and consistent with the known photometric period P = 306.9
d, demonstrating a remarkable coherence between R_{HK} and the bisector shape,
i.e. between the photosphere and the chromosphere. We discuss the complications
involved in distinguishing between companion and activity induced RV
variations.


title: Mission Concept for the Single Aperture Far-Infrared (SAFIR) Observatory

abstract:
  The Single Aperture Far-InfraRed (SAFIR) Observatory's science goals are
driven by the fact that the earliest stages of almost all phenomena in the
universe are shrouded in absorption by and emission from cool dust and gas that
emits strongly in the far-infrared and submillimeter. Over the past several
years, there has been an increasing recognition of the critical importance of
this spectral region to addressing fundamental astrophysical problems, ranging
from cosmological questions to understanding how our own Solar System came into
being. The development of large, far-infrared telescopes in space has become
more feasible with the combination of developments for the James Webb Space
Telescope and of enabling breakthroughs in detector technology. We have
developed a preliminary but comprehensive mission concept for SAFIR, as a 10
m-class far-infrared and submillimeter observatory that would begin development
later in this decade to meet the needs outlined above. Its operating
temperature (<4K) and instrument complement would be optimized to reach the
natural sky confusion limit in the far-infrared with diffraction-limited
peformance down to at least 40 microns. This would provide a point source
sensitivity improvement of several orders of magnitude over that of Spitzer or
Herschel, with finer angular resolution, enabling imaging and spectroscopic
studies of individual galaxies in the early universe. We have considered many
aspects of the SAFIR mission, including the telescope technology, detector
needs and technologies, cooling method and required technology developments,
attitude and pointing, power systems, launch vehicle, and mission operations.
The most challenging requirements for this mission are operating temperature
and aperture size of the telescope, and the development of detector arrays.


title:
Deep Extragalactic VLBI-Optical Survey (DEVOS): I. Pilot MERLIN and VLBI
  observations

abstract:
  We present the results of the pilot observations of the Deep Extragalactic
VLBI-Optical Survey (DEVOS). Our ultimate aim is to collect information on
compact structures in a large sample of extragalactic radio sources (~10000
objects) up to two orders of magnitude fainter than those studied in typical
imaging Very Long Baseline Interferometry (VLBI) surveys up until now. This
would lead to an unprecedented data base for various astrophysical, astrometric
and cosmological studies. The first global VLBI observations of the DEVOS
programme were successfully conducted in May 2002. We selected sources without
any spectral criterion from the Very Large Array (VLA) Faint Images of the
Radio Sky at Twenty-centimeters (FIRST) catalogue, that are also detected with
the Multi-Element Radio Linked Interferometer Network (MERLIN). The DEVOS pilot
sample sources are in the area of the sky that is covered by the Sloan Digital
Sky Survey (SDSS). We describe the sample selection and present high resolution
5-GHz radio images of the sources. Based on the results of this pilot study, we
estimate the outcome of and the resources needed for a full-scale DEVOS
project.


title:
Optimal Radio Window for the Detection of Ultra-High-Energy Cosmic Rays
  and Neutrinos off the Moon

abstract:
  When high-energy cosmic rays impinge on a dense dielectric medium, radio
waves are produced through the Askaryan effect. We show that at wavelengths
comparable to the length of the shower produced by an Ultra-High Energy cosmic
ray or neutrino, radio signals are an extremely efficient way to detect these
particles. Through an example it is shown that this new approach offers, for
the first time, the realistic possibility of measuring UHE neutrino fluxes
below the Waxman-Bahcall limit. It is shown that in only one month of observing
with the upcoming LOFAR radio telescope, cosmic-ray events can be measured
beyond the GZK-limit, at a sensitivity level of two orders of magnitude below
the extrapolated values.


title:
Using dCep Stars to study Northern Dwarf Irregular Galaxies of the Local
  Group

abstract:
  Dwarf galaxies in the Local Group provide a unique astrophysical laboratory.
Despite their proximity some of these systems still lack a reliable distance
determination as well as studies of their stellar content and star formation
history. We present first results of our survey of variable stars in a sample
of six Local Group dwarf irregular galaxies. We describe observational
strategies and data reduction, and discuss the lightcurves of newly found and
rediscovered dCep stars in DDO216, LeoA and GR8. Based on these data, we
present newly derived independent Cepheid distances. Other variable stars found
in our survey are discussed in a related article of this volume (Snigula et
al.).


title:
The relation between X-ray spectral index and the Eddington ratio in
  AGNs

abstract:
  Using the H$\beta$ linewidth, we obtained the virial central supermassive
black hole masses and then the Eddington ratios in a sample of broad-line AGNs
and NLS1s observed by ASCA. Combined with the data from ROSAT and Chandra
observations, We found a strong correlation between hard/soft X-ray photon
index and the Eddington ratio. Such a correlation can be understood by a
two-zone accretion flow model, in which zone is a thin disk and the inner zone
is an advection-dominated accretion flow (ADAF) disk. The relation between
X-ray photon index and the Eddington ratio may account for NLS1s with not too
steep X-ray photon index founded by SDSS. If this relation is directly related
to the accretion disk, it may also exist in the accretion disk of different
scales (such as microquasar).


title:
Doppler tomography of the transient X-ray binary Centaurus X-4 in
  quiescence

abstract:
  We present ESO-NTT low resolution spectroscopy of the neutron star X-ray
transient Cen X-4 in quiescence over a complete orbital cycle. Our data reveal
the presence of a K3-7 V companion which contributes 63% to the 5600-6900A flux
and orbits the neutron star with a velocity semi-amplitude of K_2=145.8 +/- 1.0
km s^{-1}. This, combined with a previous determination of the inclination
angle and mass ratio, yields a neutron star and companion mass of M_1=1.5 +/-
1.0 M_Sun and M_2=0.31 +/- 0.27 M_Sun, respectively. The mass donor is thus
undermassive for the inferred spectral type indicating it is probably evolved,
in agreement with previous studies. Doppler tomography of the H_alpha line
shows prominent emission located on the companion and a slightly asymmetric
accretion disc distribution similar to that seen in systems with precessing
eccentric discs. Strong H_alpha emission from the companion can be explained by
X-ray irradiation from the primary. No evidence is found for a hot spot in
H_alpha, whereas one is revealed via Doppler tomography of the HeI lines. This
can be interpreted as the hot spot and outer regions of the disc being at a
higher temperature than in other systems.


title:
The Relation between the Inclinations of Broad Line Regions and the
  Accretion Disk

abstract:
  According to the standard model, an active galactic nucleus (AGN) consists of
an inner accretion disk with a jet around a central massive black hole, and a
number of outer broad line regions (BLRs) and narrow line regions (NLRs). The
geometrical relationship between the BLRs and the accretion disk is not well
understood. Assuming the motion of the BLRs is virialized and its configuration
is disk-like, we derived its inclination to the line of sight for a sample of
AGNs from their bulge stellar velocity dispersion, their size of the BLRs and
their H$\beta$ linewidth. Compared with the inclination of the accretion disk
obtained from the X-ray Fe K$\alpha$ emission lines, we found that there is no
positive correlation between the two. Our results showed that BLRs are not
coplanar with the accretion disk and that we should be cautious of using the
BLRs inclination as the disk inclination. The non-coplanar geometry of the
outer BLRs and the inner accretion disk provides clues to the origin of BLRs
and the properties of the accretion disk. Our preferable interpretation is that
BLRs arise out of the outer part of a warped accretion disk.


title: Chandra observation of the multiple merger cluster Abell 521

abstract:
  We present the Chandra analysis of the galaxy cluster A521 (z=0.247). The
high resolution of the Chandra observation has allowed us to refine the
original merging scenario proposed for A521, and to reveal new features in its
X-ray emission. A521 has strongly substructured ICM density and temperature
maps. Its X-ray diffuse emission is elongated along a NW/SE direction (SX2) and
shows two major components, a main cluster and a northern group of galaxies.
This latter is in turn substructured, showing a clump of cold and very dense
gas centred on the BCG, and a northern tail aligned in the SX2 direction. A
compression of the X-ray isophotes is also observed South of the BCG. We
conclude that the northern group is infalling onto the main cluster along the
NW/SE direction. This hypothesis is corroborated by the presence of a hot bar
in the ICM temperature map located between the southern and northern regions,
as the gas could be compressionally heated due to the subclusters' collision.
The hot region corresponds to the eastern part of an over-dense ridge of
galaxies, along which it was originally suggested that a merging of subclusters
has recently occurred along the line of sight. An alternative hypothesis about
the origin of the hot central bar is that we could observe in projection the
shock fronts due to this older cluster-cluster collision. Two other structures
possibly interacting with the main cluster are detected on the West and
North-East sides of the BCG. We also uncover the presence of two northern edges
in the ICM density. A521 is a spectacular example of a multiple merger cluster
made up by several substructures converging at different epochs towards the
centre of the system. The very pertubed dynamical state of this cluster is also
confirmed by our discovery of a radio relic in its South-East region.


title: Scaling solutions in scalar-tensor cosmologies

abstract:
  The possibility of a connection between dark energy and gravity through a
direct coupling in the Lagrangian of the underlying theory has acquired an
increasing interest due to the recently discovered capability of the extended
quintessence model to encompass the fine-tuning problem of the cosmological
constant. The gravity induced "R-boost" mechanism is indeed responsible for an
early, enhanced scalar field dynamics, by virtue of which the residual imprint
of a wide set of initial field values is cancelled out. The initial conditions
problem is particularly relevant, as the most recent observations indicate that
the dark energy equation of state approaches, at the present time, the
cosmological constant value, wDE = -1; if confirmed, such observational
evidence would cancel the advantage of a standard, minimally coupled scalar
field as a Dark Energy candidate instead of the cosmological constant, because
of the huge fine tuning it would require. We give here a general classification
of the scalar-tensor gravity theories admitting R-boost solutions scaling as a
power of the cosmological redshift, outlining those behaving as an attractor
for the quintessence field. In particular, we show that all the R-boost
solutions with the dark energy density scaling as the relativistic matter or
shallower represent attractors. This analysis is exhaustive as for the
classification of the couplings which admit R-boost and the subsequent
enlargement of the basin of attraction enclosing the initial scalar field
values.


title: Two Clusters with Radio-quiet Cooling Cores

abstract:
  Radio lobes inflated by active galactic nuclei at the centers of clusters are
a promising candidate for halting condensation in clusters with short central
cooling times because they are common in such clusters. In order to test the
AGN-heating hypothesis, we obtained Chandra observations of two clusters with
short central cooling times yet no evidence for AGN activity: Abell 1650 and
Abell 2244. The cores of these clusters indeed appear systematically different
from cores with more prominent radio emission. They do not have significant
central temperature gradients, and their central entropy levels are markedly
higher than in clusters with stronger radio emission, corresponding to central
cooling times ~ 1 Gigayear. Also, there is no evidence for fossil X-ray
cavities produced by an earlier episode of AGN heating. We suggest that either
(1) the central gas has not yet cooled to the point at which feedback is
necessary to prevent it from condensing, possibly because it is conductively
stabilized, or (2) the gas experienced a major heating event $\gtrsim 1$ Gyr in
the past and has not required feedback since then. The fact that these clusters
with no evident feedback have higher central entropy and therefore longer
central cooling times than clusters with obvious AGN feedback strongly suggests
that AGNs supply the feedback necessary to suppress condensation in clusters
with short central cooling times.


title:
Chandra Observations of Gas Stripping in the Elliptical Galaxy NGC 4552
  in the Virgo Cluster

abstract:
  We use a 54.4 ks Chandra observation to study ram-pressure stripping in
NGC4552 (M89), an elliptical galaxy in the Virgo Cluster. Chandra images in the
0.5-2 keV band show a sharp leading edge in the surface brightness 3.1 kpc
north of the galaxy center, a cool (kT =0.51^{+0.09}_{-0.06} keV) tail with
mean density n_e ~5.4 +/- 1.7 x 10^{-3} cm^{-3} extending ~10 kpc to the south
of the galaxy, and two 3-4 kpc horns of emission extending southward away from
the leading edge. These are all features characteristic of supersonic
ram-pressure stripping of galaxy gas, due to NGC4552's motion through the
surrounding Virgo ICM. Fitting the surface brightness profile and spectra
across the leading edge, we find the galaxy gas inside the edge is cooler (kT =
0.43^{+0.03}_{-0.02} keV) and denser (n_e ~ 0.010 cm^{-3}) than the surrounding
Virgo ICM (kT = 2.2^{+0.7}_{-0.4} keV and n_e = 3.0 +/- 0.3 x 10^{-4} cm^{-3}).
The resulting pressure ratio between the free-streaming ICM and cluster gas at
the stagnation point is ~7.6^{+3.4}_{-2.0} for galaxy gas metallicities of
0.5^{+0.5}_{-0.3} Zsolar, which suggests that NGC4552 is moving supersonically
through the cluster with a velocity v ~ 1680^{+390}_{-220} km/s (Mach
2.2^{+0.5}_{-0.3}) at an angle xi ~ 35 +/- 7 degrees towards us with respect to
the plane of the sky.


title:
A Possible Origin of Magnetic Fields in Galaxies and Clusters: Strong
  Magnetic fields at z~10?

abstract:
  We propose that strong magnetic fields should be generated at shock waves
associated with formation of galaxies or clusters of galaxies by the Weibel
instability, an instability in collisionless plasmas. The strength of the
magnetic fields generated through this mechanism is close to the order of those
observed in galaxies or clusters of galaxies at present. If the generated
fields do not decay rapidly, this indicates that strong amplification of
magnetic fields after formation of galaxies or clusters of galaxies is not
required. This mechanism could have worked even at a redshift of ~10, and
therefore the generated magnetic fields may have affected the formation of
stars in protogalaxies. This model will partially be confirmed by future
observations of nearby clusters of galaxies. Mechanisms that preserve the
magnetic fields for a long time without considerable decay are discussed.


title: How Large Are the Bars in Barred Galaxies?

abstract:
  I present a study of the sizes (semimajor axes) of bars in disc galaxies,
combining a detailed study of 65 S0-Sb galaxies with measurements of 70 Sb-Sd
galaxies from Martin (1995). As has been noted before with smaller samples,
bars in early-type (S0-Sb) galaxies are clearly larger than bars in late-type
(Sc-Sd) galaxies; this is true both for relative sizes (bar length as fraction
of isophotal radius R_25 or exponential disc scale length h) and absolute sizes
(kpc). S0-Sab bars extend to ~1-10 kpc (mean ~3.3 kpc), ~0.2-0.8 R_25 (mean
\~0.38 R_25) and ~0.5-2.5 h (mean ~1.4 h). Late-type bars extend to only
\~0.5-3.5 kpc, 0.05-0.35 R_25 and 0.2-1.5 h; mean sizes are ~1.5 kpc, 0.14 R_25
and 0.6 h. Sb galaxies resemble earlier-type galaxies in terms of bar size
relative to h; their smaller R_25-relative sizes may be a side effect of higher
star formation, which increases R_25 but not h. For S0-Sbc galaxies, bar size
correlates well with disc size (both R_25 and h); these correlations are
stronger than the known correlation with M_B. All correlations appear to be
weaker or absent for late-type galaxies; in particular, there seems to be no
correlation between bar size and either h or M_B for Sc-Sd galaxies.
  I show that the bars detected in HST near-IR images at z ~ 1 by Sheth et al.
(2003) have absolute sizes consistent with those in bright, nearby S0-Sb
galaxies. I also compare the sizes of real bars with those produced in
simulations, and discuss some possible implications for scenarios of secular
evolution along the Hubble sequence. Simulations often produce bars as large as
-- or larger than -- those seen in S0-Sb galaxies, but rarely any as small as
those in Sc-Sd galaxies. (Abridged.)


title: Effects of mass loss for highly-irradiated giant planets

abstract:
  We present calculations for the evolution and surviving mass of
highly-irradiated extrasolar giant planets (EGPs) at orbital semimajor axes
ranging from 0.023 to 0.057 AU using a generalized scaled theory for mass loss,
together with new surface-condition grids for hot EGPs and a consistent
treatment of tidal truncation. Theoretical estimates for the rate of
energy-limited hydrogen escape from giant-planet atmospheres differ by two
orders of magnitude, when one holds planetary mass, composition, and
irradiation constant. Baraffe et al. (2004, A&A 419, L13-L16) predict the
highest rate, based on the theory of Lammer et al. (2003, Astrophys. J. 598,
L121-L124). Scaling the theory of Watson et al. (1981, Icarus 48, 150-166) to
parameters for a highly-irradiated exoplanet, we find an escape rate ~102 lower
than Baraffe's. With the scaled Watson theory we find modest mass loss,
occurring early in the history of a hot EGP. In this theory, mass loss
including the effect of Roche-lobe overflow becomes significant primarily for
masses below a Saturn mass, for semimajor axes = 0.023 AU. This contrasts with
the Baraffe model, where hot EGPs are claimed to be remnants of much more
massive bodies, originally several times Jupiter and still losing substantial
mass fractions at present.


title: Cosmological constraints from clustering properties of galaxy clusters

abstract:
  In this paper, we discuss improvements of the Suto et al. (2000) model, in
the light of recent theoretical developments (new theoretical mass functions, a
more accurate mass-temperature relation and an improved bias model) to predict
the clustering properties of galaxy clusters and to obtain constraints on
cosmological parameters. We re-derive the two-point correlation function of
clusters of galaxies for OCDM and LambdaCDM cosmological models, and we compare
these results with the observed spatial correlation function for clusters in
RASS1 (ROSAT All-Sky Survey 1), and in XBACs (X-RAY Brighest Abell-Type)
samples. The comparison shows that the best agreement is obtained for the
LambdaCDM model with Omega=0.3. The values of the correlation length obtained,
(r_\simeq 28.2 \pm 5.2 \rm h^{-1}} Mpc for LambdaCDM), are larger than those
found in the literature and comparable with the results found in Borgani,
Plionis & Kolokotronis (1999). (REST IN THE PAPER ABSTRACT)


title: Identification of 8 INTEGRAL hard X-ray sources with Chandra

abstract:
  We report the results of identification of 8 hard X-ray sources discovered by
the INTEGRAL observatory during the ongoing all-sky survey. These sources have
been observed by Chandra. In 6 cases a bright X-ray source was found within the
INTEGRAL localization region, which permitted to unambigously identify 5 of the
objects with nearby galaxies, implying that they have an active galactic
nucleus (AGN), whereas one source is likely an X-ray binary in LMC. 4 of the 5
newly discovered AGNs have measured redshifts in the range 0.025-0.055. The
X-ray spectra reveal the presence of significant amounts of absorbing gas (NH
in the range 10^22-10^24 cm^-2) in all 5 AGNs, demonstrating that INTEGRAL is
starting to fill in the sample of nearby obscured AGNs.


title:
The Number Density of Old Passively-Evolving Galaxies at z=1 in the
  Subaru/XMM-Newton Deep Survey Field

abstract:
  We obtained the number counts and the rest-frame B-band luminosity function
of the color-selected old passively-evolving galaxies (OPEGs) at z=1 with very
high statistical accuracy using a large and homogeneous sample of about 4000
such objects with z' <25 detected in the area of 1.03 deg^2 in the
Subaru/XMM-Newton Deep Survey (SXDS) field. Our selection criteria are defined
on the i'-z' and R-z' color-magnitude plane so that OPEGs at z=0.9-1.1 with
formation redshift z_f=2-10 are properly sampled. The limiting magnitude
corresponds to the luminosity of galaxies with M_*+3 at z=0. We made a pilot
redshift observations for 99 OPEG candidates with 19 < z' < 22 and found that
at least 78% (73/93) of the entire sample, or 95% (73/77) of these whose
redshifts were obtained are indeed lie between z=0.87 and 1.12 and the most of
their spectra show the continuum break and strong Ca H and K lines, indicating
that these objects are indeed dominated by the old stellar populations. We then
compare our results with the luminosity functions of the color- or the
morphologically-selected early type galaxies at z=0 taking the evolutionary
factor into account and found that the number density of old passive galaxies
with sim M_* magnitude at z~1 averaged over the SXDS area is 40-60% of the
equivalently red galaxies and 60-85% of the morphologically-selected E/S0
galaxies at z=0 depending on their luminosity evolution. It is revealed that
more than half, but not all, of the present-day early-type galaxies had already
been formed into quiescent passive galaxies at z=1.


title: Supernova remnant S147 and its associated neutron star(s)

abstract:
  The supernova remnant S147 harbors the pulsar PSR J0538+2817 whose
characteristic age is more than an order of magnitude greater than the
kinematic age of the system (inferred from the angular offset of the pulsar
from the geometric center of the supernova remnant and the pulsar proper
motion). To reconcile this discrepancy we propose that PSR J0538+2817 could be
the stellar remnant of the first supernova explosion in a massive binary system
and therefore could be as old as its characteristic age. Our proposal implies
that S147 is the diffuse remnant of the second supernova explosion (that
disrupted the binary system) and that a much younger second neutron star (not
necessarily manifesting itself as a radio pulsar) should be associated with
S147. We use the existing observational data on the system to suggest that the
progenitor of the supernova that formed S147 was a Wolf-Rayet star (so that the
supernova explosion occurred within a wind bubble surrounded by a massive
shell) and to constrain the parameters of the binary system. We also restrict
the magnitude and direction of the kick velocity received by the young neutron
star at birth and find that the kick vector should not strongly deviate from
the orbital plane of the binary system.


title:
A theoretical study of the luminosity temperature relation for clusters
  of galaxies

abstract:
  A luminosity-temperature relation for clusters of galaxies is derived. The
two models used, take into account the angular momentum acquisition by the
proto-structures during their expansion and collapse. The first one is a
modification of the self-similar model (SSM) while the second one is a
modification of the Punctuated Equilibria Model (Cavaliere et al. 1999). In
both models the mass-temperature relation (M-T) used is based on the
calculations of Del Popolo (2002b). We show that the above models lead, in
X-rays, to a luminosity-temperature relation that scales as L \propto T^5, at
scale of groups, flattening to L \propto T^3 for rich clusters and converging
to L \propto T^2 at higher temperatures. However a fundamental result of our
paper is that the non-similarity in the L-T relation, can be explained by a
simple model that takes into account the amount of the angular momentum of a
proto-structure. This result is in disagreement with the widely accepted idea
that the above non-similarity is due to non-gravitating processes as those of
heating/cooling.


title:
Close Binary Interactions of Intermediate-Mass Black Holes: Possible
  Ultra-Luminous X-ray Sources?

abstract:
  While many observed ultra-luminous X-ray sources (ULXs, Lx > 10^39 erg s^-1)
could be extragalactic X-ray binaries (XRBs) emitting close to the Eddington
limit, the highest-luminosity ULXs (Lx > 3x10^39 erg s^-1) exceed the isotropic
Eddington luminosity for even high-stellar-mass accreting black hole XRBs. It
has been suggested that these highest-luminosity ULXs may contain accreting
intermediate-mass black hole (IMBH) binaries. We consider this hypothesis for
dense, young (about 100 Myr) stellar clusters where we assume that a 50-500
solar mass central IMBH has formed through runaway growth of a massive star.
Using numerical simulations of the dynamics and evolution of the central black
hole's captured companions, we obtain estimates of the incidence of mass
transfer phases and possible ULX activity throughout the IMBH's evolutionary
history. We find that, although it is common for the central black hole to
acquire binary companions, there is a very low probability that these
interacting binaries will become observable ULX sources.


title: A high-frequency radio survey of low-luminosity active galactic nuclei

abstract:
  We investigate the high-frequency radio spectra of twenty low-luminosity
active galactic nuclei (LLAGNs) with compact radio cores. Our millimetre survey
with the Nobeyama Millimetre Array (NMA) and analyses of submillimetre archival
data that had been obtained with the Submillimetre Common User Bolometer Array
(SCUBA) on the James Clerk Maxwell Telescope (JCMT) reveal the following
properties. At least half of the LLAGNs show inverted spectra between 15 and 96
GHz; we use published data at 15 GHz with the Very Large Array (VLA) in a
0.15-arcsec resolution and our measurements at 96 GHz with the NMA in a
7-arcsec resolution. The inverted spectra are not artificially made due to
their unmatched beam sizes, because of little diffuse contamination from dust,
H II regions, or extended jets in these LLAGNs. Such high-frequency inverted
spectra are apparently consistent with a `submillimetre bump', which is
predicted by an advection-dominated accretion flow (ADAF) model. We find a
strong correlation between the high-frequency spectral index and low-frequency
core power measured with very-long-baseline-interferometry (VLBI) instruments.
The inverted spectra were found exclusively in low-core-power sources, while
steep spectra were in high-core-power ones with prominent pc-scale jets. This
suggests that the ADAF and nonthermal jets may coexists. The flux ratios
between disc and jet seem to be different from LLAGN to LLAGN; disc components
can be seen in nuclear radio spectra only if the jets are faint.


title:
Relationship between the rise width and the full width of gamma-ray
  burst pulses and its implications in terms of the fireball model

abstract:
  Kocevski et al. (2003) found that there is a linear relation between the rise
width and the full width of gamma-ray burst pulses detected by the BATSE
instrument based on their empirical functions. Motivated by this, we
investigate the relationship based on Qin et al. (2004) model. Theoretical
analysis shows that each of the two quantities, the rise width and the full
width of observed pulse, is proportional to $\Gamma^{-2}\Delta\tau_{\theta,\rm
FWHM}\frac{R_c}{c}$, where $\Gamma$ is the Lorentz factor for the bulk motion,
$\Delta \tau_{\theta,\rm FWHM}$ is a local pulse's width, $R_{c}$ is the radius
of fireballs and c is the velocity of light. We employ the observed pulses
coming from four samples to study the relationship and find that: (1) Merely
the curvature effect could produce the relationship with the same slope as
those derived from Qin et al. (2004) model in the rise width vs. the full width
panel. (2) Gamma-ray burst pulses, long or short ones (selected from the short
and long GRBs), follow the same sequence in the rise width vs. the full width
panel, with the shorter pulses at the end of this sequence. (3) All GRBs may
intrinsically result from local Gaussian pulses. These features place
constraints on the physical mechanism(s) for producing long and short GRBs.


title: Orbital migration and the period distribution of exoplanets

abstract:
  We use the model for the migration of planets introduced in Del Popolo,
Yesilyurt & Ercan (2003) to calculate the observed mass and semimajor axis
distribution of extra-solar planets. The assumption that the surface density in
planetesimals is proportional to that of gas is relaxed, and in order to
describe disc evolution we use a method which, using a series of simplifying
assumptions, is able to simultaneously follow the evolution of gas and solid
particles for up to $10^7 {\rm yr}$. The distribution of planetesimals obtained
after $10^7 {\rm yr}$ is used to study the migration rate of a giant planet
through the model of this paper. The disk and migration models are used to
calculate the distribution of planets as function of mass and semimajor axis.
The results show that the model can give a reasonable prediction of planets'
semi-major axes and mass distribution. In particular there is a pile-up of
planets at $a \simeq 0.05$ AU, a minimum near 0.3 AU, indicating a paucity of
planets at that distance, and a rise for semi-major axes larger than 0.3 AU,
out to 3 AU. The semi-major axis distribution shows that the more massive
planets (typically, masses larger than $4 M_{\rm J}$) form preferentially in
the outer regions and do not migrate much. Intermediate-mass objects migrate
more easily whatever the distance they form, and that the lighter planets
(masses from sub-Saturnian to Jovian) migrate easily.


title:
Global Perturbation Configurations in a Composite Disc System with an
  Isopedic Magnetic Field

abstract:
  We construct stationary global configurations of both aligned and unaligned
logarithmic spiral perturbations in a composite disc system of stellar and
isopedically magnetized gaseous singular isothermal discs (SIDs) coupled by
gravity. The thin gaseous SID is threaded across by a vertical magnetic field
B_z with a constant ratio of the surface gas mass density to B_z. There exist
two classes of stationary magnetohydrodynamic (MHD) solutions with in-phase and
out-of-phase density perturbations. For both aligned and unaligned cases with
azimuthal periodicities |m|\geq 2 (m is an integer), there may be two, one, and
no solution situations, depending on the chosen parameters. For the transition
criteria from an axisymmetric equilibrium to aligned secular bar-like
instabilities, the corresponding T/|W| ratio can be much lower than the
oft-quoted value of T/|W|\sim 0.14, where T is the total rotational kinetic
energy and W is the total gravitational potential energy plus the magnetic
energy. The T/|W| ratios for the two sets of solutions in different ranges are
separated by m/(4m+4). For the unaligned cases, we study marginal stabilities
for axisymmetric (m=0) and non-axisymmetric (m\neq 0) disturbances. The
gravitational influence of an axisymmetric dark matter halo on the background
is also examined. The global analytical solutions and their properties are
valuable for testing and benchmarking numerical MHD codes. Our model analysis
contains more realistic elements and offers useful insights into the structures
and dynamics of disc galaxies consisting of stars and magnetized interstellar
medium. In the presence of star burst activities, supernovae, hypernovae,
superbubbles etc., our open magnetic field geometry in disc galaxies bears
strong implications on circumnuclear and spiral galactic winds.


title: Early Afterglows in Wind Environments Revisited

abstract:
  When a cold shell sweeps up the ambient medium, a forward shock and a reverse
shock will form. We analyze the reverse-forward shocks in a wind environment,
including their dynamics and emission. An early afterglow is emitted from the
shocked shell, e.g., an optical flash may emerge. The reverse shock behaves
differently in two approximations: relativistic and Newtonian cases, which
depend on the parameters, e.g., the initial Lorentz factor of the ejecta. If
the initial Lorentz factor is much less than $114 E_{53}^{1/4}
\Delta_{0,12}^{-1/4} A_{*,-1}^{-1/4}$, the early reverse shock is Newtonian.
This may take place for the wider of a two-component jet, an orphan afterglow
caused by a low initial Lorentz factor, and so on. The synchrotron self
absorption effect is significant especially for the Newtonian reverse shock
case, since the absorption frequency $\nu_a$ is larger than the cooling
frequency $\nu_c$ and the minimum synchrotron frequency $\nu_m$ for typical
parameters. For the optical to X-ray band, the flux is nearly unchanged with
time during the early period, which may be a diagnostic for the low initial
Lorentz factor of the ejecta in a wind environment. We also investigate the
early light curves with different wind densities, and compare them with these
in the ISM model.


title:
Detecting Earth-Like Extra-Solar Planets from Antarctica by
  Gravitational Microlensing

abstract:
  Earth-like extra-solar planets may be detected with 1-2m class telescopes
using the gravitational microlensing technique. The essential requirement is
the ability to be able to carry out continuous observations of the galactic
bulge. A telescope situated at Dome A or Dome C in Antarctica would be
eminently suitable. Two possible observing strategies are described here. One
employs a 1m visible (V and I passbands) telescope, the other a 2m wide-field
near infrared telescope. Either telescope could allow a rough measurement of
the abundance of Earth-like planets in the Milky Way to be made in a few years.
Useful measurements could also be made on stellar atmospheres.


title:
Cosmic Variance In the Transparency of the Intergalactic Medium After
  Reionization

abstract:
  Following the completion of cosmic reionization, the mean-free-path of
ionizing photons was set by a population of Ly-limit absorbers. As the
mean-free-path steadily grew, the intensity of the ionizing background also
grew, thus lowering the residual neutral fraction of hydrogen in ionization
equilibrium throughout the diffuse intergalactic medium (IGM). Ly-alpha photons
provide a sensitive probe for tracing the distribution of this residual
hydrogen at the end of reionization. Here we calculate the cosmic variance
among different lines-of-sight in the distribution of the mean Ly-alpha optical
depths. We find fractional variations in the effective post-reionization
optical depth that are of order unity on a scale of ~100 co-moving Mpc, in
agreement with observations towards high-redshift quasars. Significant
contributions to these variations are provided by the cosmic variance in the
density contrast on the scale of the mean-free-path for ionizing photons, and
by fluctuations in the ionizing background induced by delayed or enhanced
structure formation. Cosmic variance results in a highly asymmetric
distribution of transmission through the IGM, with fractional fluctuations in
Ly-alpha transmission that ar larger than in Ly-beta transmission.


title: Candidate spectroscopic binaries in the Sloan Digital Sky Survey

abstract:
  We have examined the radial velocity data for stars spectroscopically
observed by the Sloan Digital Sky Survey (SDSS) more than once to investigate
the incidence of spectroscopic binaries, and to evaluate the accuracy of the
SDSS stellar radial velocities. We find agreement between the fraction of stars
with significant velocity variations and the expected fraction of binary stars
in the halo and thick disk populations. The observations produce a list of 675
possible new spectroscopic binary stars and orbits for eight of them.


title: Elemental abundances in the Blanco 1 open cluster

abstract:
  High resolution spectroscopy is used to determine the detailed chemical
abundances of a group of eight F- and G-type stars in the young open cluster
Blanco 1. An average [Fe/H] of +0.04 +/- 0.02 (internal error) +/- 0.04
(external error) is found, considerably lower than a previous spectroscopic
estimate for this cluster. The difference is due mainly to our adoption of
significantly cooler temperatures which are consistent with both photometric
and spectroscopic constraints. Blanco~1 exhibits sub-solar [Ni/Fe] (-0.18 +/-
0.01 +/- 0.01), [Si/Fe] (-0.09$ +/- 0.02 +/- 0.03), [Mg/Fe] (-0.14 +/- 0.02 +/-
0.03) and [Ca/Fe] (-0.09 +/- 0.03 +/- 0.03); ratios which are not observed
among nearby field stars. The material from which Blanco 1 formed may not have
been well mixed with interstellar matter in the galactic disc, which tallies
with its current location about 240pc below the galactic plane. A simultaneous
deficit of Ni and alpha elements with respect to Fe is hard to reconcile with
most published models of yields from supernovae of types Ia and II. The revised
abundances for Blanco 1 indicate that overall radiative opacities in its stars,
and hence convective zone properties at a given mass, are similar to those in
the Pleiades at approximately the same age. This can explain a previous
observation that the Li depletion patterns of G- and K-type stars in the two
clusters are indistinguishable. The lower overall metallicity of Blanco 1 now
make it less attractive as a target for discovering transiting, short period
exoplanets.


title: GRAVITY: The AO-Assisted, Two-Object Beam-Combiner Instrument

abstract:
  We present the proposal for the infrared adaptive optics (AO) assisted,
two-object, high-throughput, multiple-beam-combiner GRAVITY for the VLTI. This
instrument will be optimized for phase-referenced interferometric imaging and
narrow-angle astrometry of faint, red objects. Following the scientific
drivers, we analyze the VLTI infrastructure, and subsequently derive the
requirements and concept for the optimum instrument. The analysis can be
summarized with the need for highest sensitivity, phase referenced imaging and
astrometry of two objects in the VLTI beam, and infrared wavefront-sensing.
Consequently our proposed instrument allows the observations of faint, red
objects with its internal infrared wavefront sensor, pushes the optical
throughput by restricting observations to K-band at low and medium spectral
resolution, and is fully enclosed in a cryostat for optimum background
suppression and stability. Our instrument will thus increase the sensitivity of
the VLTI significantly beyond the present capabilities. With its two fibers per
telescope beam, GRAVITY will not only allow the simultaneous observations of
two objects, but will also push the astrometric accuracy for UTs to 10
micro-arcsec, and provide simultaneous astrometry for up to six baselines.


title:
Highly ionized iron absorption lines from outflowing gas in the X-ray
  spectrum of NGC 1365

abstract:
  We present the discovery of four absorption lines in the X-ray spectrum of
the Seyfert Galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The lines are
detected with high statistical confidence (from >20sigma for the strongest to
\~4sigma for the weakest) in two XMM-Newton observations 60 ksec long. We also
detect the same lines, with lower signal-to-noise (but still >2sigma for each
line) in two previous shorter (~10 ksec) XMM observations. The spectral
analysis identifies these features as FeXXV and FeXXVI Kalpha and Kbeta lines,
outflowing with velocities varying between ~1000 to ~5000 km/s among the
observations. These are the highest quality detections of such lines so far.
The high equivalent widths (EW(Kalpha)~100 eV) and the Kalpha/Kbeta ratios
imply that the lines are due to absorption of the AGN continuum by a highly
ionized gas with column density N_H~5x10^23 cm^{-2}


title: Solar-like oscillations in alpha Centauri B

abstract:
  We have made velocity observations of the star alpha Cen B from two sites,
allowing us to identify 37 oscillation modes with l=0-3. Fitting to these modes
gives the large and small frequency separations as a function of frequency. The
mode lifetime, as measured from the scatter of the oscillation frequencies
about a smooth trend, is similar to that in the Sun. Limited observations of
the star delta Pav show oscillations centred at 2.3 mHz with peak amplitudes
close to solar. We introduce a new method of measuring oscillation amplitudes
from heavily-smoothed power density spectra, from which we estimated amplitudes
for alpha Cen A and B, beta Hyi, delta Pav and the Sun. We point out that the
oscillation amplitudes may depend on which spectral lines are used for the
velocity measurements.


title:
Harassment Origin for Kinematic Substructures in Dwarf Elliptical
  Galaxies?

abstract:
  We have run high resolution N-body models simulating the encounter of a dwarf
galaxy with a bright elliptical galaxy. The dwarf absorbs orbital angular
momentum and shows counter-rotating features in the external regions of the
galaxy. To explain the core-envelope kinematic decoupling observed in some
dwarf galaxies in high-density environments requires nearly head-on collisions
and very little dark matter bound to the dwarf. These kinematic structures
appear under rather restrictive conditions. As a consequence, in a cluster like
Virgo ~1% of dwarf galaxies may present counter-rotation formed by harassment.


title:
FUSE determination of a low deuterium abundance along an extended sight
  line in the Galactic disk

abstract:
  We present a study of the deuterium abundance along the extended sight line
(2.7kpc) toward HD 90087 with FUSE. Both in terms of distance and column
densities, HD 90087 has the longest and densest sight line observed in the
Galactic disk for which a deuterium abundance has been measured from UV
absorption lines. Because many interstellar clouds are probed along this sight
line, possible variations in the properties of individual clouds should be
averaged out. This would yield a deuterium abundance which is characteristic of
the interstellar medium on scales larger than the Local Bubble. We report
D/O=(1.7+/-0.7)e-2 and D/H=(9.8+/-3.8)e-6 (2 sigma). Our new results confirm
that the gas-phase deuterium abundance in the distant interstellar medium is
significantly lower than the one measured within the Local Bubble. We
supplement our study with a revision of the oxygen abundance toward the
moderately distant star Feige 110 (~200 pc). Excluding saturated lines from the
fits of the FUSE spectra is critical; this led us to derive an OI column
density about two times larger than the one previously reported for Feige 110.
The corresponding updated D/O ratio on this sight line is D/O=(2.6+/-1.0)e-2 (2
sigma), which is lower than the one measured within the Local Bubble. The
dataset available now outside the Local Bubble shows a contrast between the
constancy of D/O and the variability of D/H. As oxygen is considered to be a
good proxy for hydrogen within the interstellar medium, this discrepancy is
puzzling. (abstract abridged)


title: New analysis of the SN 1987A neutrinos with a flexible spectral shape

abstract:
  We analyze the neutrino events from the supernova (SN) 1987A detected by the
Kamiokande II (KII) and Irvine-Michigan-Brookhaven (IMB) experiments. For the
time-integrated flux we assume a quasi-thermal spectrum of the form
$(E/E_0)^\alpha e^{-(\alpha+1)E/E_0}$ where $\alpha$ plays the role of a
spectral index. This simple representation not only allows one to fit the total
energy $E_{\rm tot}$ emitted in $\bar\nu_e$ and the average energy
$<E_{\bar\nu_e}>$, but also accommodates a wide range of shapes, notably
anti-pinched spectra that are broader than a thermal distribution. We find that
the pile-up of low-energy events near threshold in KII forces the best-fit
value for $\alpha$ to the lowest value of any assumed prior range. This applies
to the KII events alone as well as to a common analysis of the two data sets.
The preference of the data for an ``unphysical'' spectral shape implies that
one can extract meaningful values for $<E_{\bar\nu_e}>$ and $E_{\rm tot}$ only
if one fixes a prior value for $\alpha$. The tension between the KII and IMB
data sets and theoretical expectations for $<E_{\bar\nu_e}>$ is not resolved by
an anti-pinched spectrum.


title:
INTEGRAL and RXTE observations of accreting millisecond pulsar IGR
  J00291+5934 in outburst

abstract:
  Simultaneous observations of the accretion-powered millisecond pulsar IGR
J00291+5934 by International Gamma-Ray Astrophysics Laboratory and Rossi X-ray
Timing Explorer during the 2004 December outburst are analysed. The average
spectrum is well described by thermal Comptonization with an electron
temperature of 50 keV and Thomson optical depth tau_T ~ 1 in a slab geometry.
The spectral shape is almost constant during the outburst. We detect a spin-up
of the pulsar with nudot=8.4x10E-13 Hz/s. The ISGRI data reveal the pulsation
of X-rays at a period of 1.67 milliseconds up to ~150 keV. The pulsed fraction
is shown to increase from 6 per cent at 6 keV to 12--20 per cent at 100 keV.
This is naturally explained by the action of the Doppler effect the
exponentially cutoff Comptonization spectrum from the hot spot. The nearly
sinusoidal pulses show soft lags with complex energy dependence, increasing up
to 7 keV, then decreasing to 15 keV, and seemingly saturating at higher
energies.


title:
Mass Determination of Groups of Galaxies: Effects of the Cosmological
  Constant

abstract:
  The spherical infall model first developed by Lema\^{i}tre and Tolman was
modified in order to include the effects of a dark energy term. The resulting
velocity-distance relation was evaluated numerically. This equation, when
fitted to actual data, permits the simultaneous evaluation of the central mass
and of the Hubble parameter. Application of this relation to the Local Group,
when the dark energy is modeled by a cosmological constant, yields a total mass
for the M31-Milky Way pair of (2.5 +/- 0.7) x 10^12 M\_sun, a Hubble parameter
H\_0 = 74 +/- 4 km s^-1 Mpc^-1 and a 1-D velocity dispersion for the flow of
about 39 km s^-1. The zero-velocity and the marginally bound surfaces of the
Local Group are at about 1.0 and 2.3 Mpc respectively from the center of mass.
A similar analysis for the Virgo cluster yields a mass of (1.10 +/- 0.12) x
10^15 M\_sun and H\_0 = 65 +/- 9 km s^-1 Mpc^-1. The zero-velocity is located
at a distance of 8.6 +/- 0.8 Mpc from the center of the cluster. The predicted
peculiar velocity of the Local Group towards Virgo is about 190 kms^-1, in
agreement with other estimates. Slightly lower masses are derived if the dark
energy is represented by a fluid with an equation of state P = w\epsilon with w
= -2/3.


title:
Two years of INTEGRAL monitoring of the Soft Gamma-Ray Repeater SGR
  1806-20: from quiescence to frenzy

abstract:
  SGR 1806-20 has been observed for more than 2 years with the INTEGRAL
satellite. In this period the source went from a quiescent state into a very
active one culminating in a giant flare on December 27 2004. Here we report on
the properties of all the short bursts detected with INTEGRAL before the giant
flare. We derive their number-intensity distribution and confirm the
hardness-intensity correlation for the bursts found by Gotz et al. (2004a). Our
sample includes a very bright outburst that occurred on October 5 2004, during
which over one hundred bursts were emitted in 10 minutes, involving an energy
release of 3 x 1E42 erg. We present a detailed analysis of it and discuss our
results in the framework of the magnetar model.


title: Three-Dimensional Bar Structure and Disc/Bulge Secular Evolution

abstract:
  Kn-band imaging of a sample of 30 edge-on spiral galaxies with a boxy or
peanut-shaped (B/PS) bulge is discussed. Galaxies with a B/PS bulge tend to
have a more complex morphology than galaxies with other bulge types,
unsharp-masked images revealing structures that trace the major orbit families
of three-dimensional bars. Their surface brightness profiles are also more
complex, typically containing 3 or more clearly separated regions, including a
shallow or flat intermediate region (Freeman Type II profiles), suggestive of
bar-driven transfer of angular momentum and radial redistribution of material.
The data also suggest abrupt variations of the discs' scaleheights, as expected
from the vertical resonances and instabilities present in barred discs but
contrary to conventional wisdom. Counter to the standard `bulge + disc' model,
we thus propose that galaxies with a B/PS bulge are composed of a thin
concentrated disc (a disc-like bulge) contained within a partially thick bar
(the B/PS bulge), itself contained within a thin outer disc. The inner disc
most likely formed through bar-driven processes while the thick bar arises from
buckling instabilities. Both are strongly coupled dynamically and are formed
mostly of the same (disc) material.


title: EGRET Excess of Diffuse Galactic Gamma Rays as Tracer of Dark Matter

abstract:
  The public data from the EGRET space telescope on diffuse Galactic gamma rays
in the energy range from 0.1 to 10 GeV are reanalyzed with the purpose of
searching for signals of Dark Matter annihilation (DMA). The analysis confirms
the previously observed excess for energies above 1 GeV in comparison with the
expectations from conventional Galactic models. In addition, the excess was
found to show all the key features of a signal from Dark Matter Annihilation
(DMA): a) the excess is observable in all sky directions and has the same shape
everywhere, thus pointing to a common source; b) the shape corresponds to the
expected spectrum of the annihilation of non-relativistic massive particles
into - among others - neutral $\pi^0$ mesons, which decay into photons. From
the energy spectrum of the excess we deduce a WIMP mass between 50 and 100 GeV,
while from the intensity of the excess in all sky directions the shape of the
halo could be reconstructed. The DM halo is consistent with an almost spherical
isothermal profile with substructure in the Galactic plane in the form of
toroidal rings at 4 and 14 kpc from the center. These rings lead to a peculiar
shape of the rotation curve, in agreement with the data, which proves that the
EGRET excess traces the Dark Matter.


title:
Toward a Census of Variable Stars in Northern Local Group Dwarf
  Irregular Galaxies

abstract:
  Dwarf galaxies in the local group provide a unique astrophysical laboratory.
In particular, they allow us to probe pulsating (and other) variable stars in
low-metallicity environments with abundances below that of the SMC. Our
observing program, described in detail by C. G\"ossl's contribution, yields a
large number of intrinsically bright variable stars that can serve as probes of
the stellar population and star formation history of these galaxies. Most
prominent are pulsation variables like Miras (LPVs) and $\delta$ Cep stars, but
we also find other types of variable stars, e.g. RV Tauri stars, irregular red
variables etc. We present a preliminary census for the three galaxies DDO 216,
Leo A and GR8.


title:
Probing the formation of intermediate- to high-mass stars in
  protoclusters: A detailed millimeter study of the NGC 2264 clumps

abstract:
  We present the results of dust continuum and molecular line observations of
two massive cluster-forming clumps, NGC 2264-C and NGC 2264-D, including
extensive mapping performed with the MAMBO bolometer array and the HERA
heterodyne array on the IRAM 30m telescope. Both NGC 2264 clumps are located in
the Mon OB1 giant molecular cloud complex, adjacent to one another. Twelve and
fifteen compact millimeter continuum sources (i.e. MMSs) are identified in
clumps C and D, respectively. Evidence for widespread infall motions is found
in, e.g., HCO+(3-2) or CS(3-2) in both NGC 2264-C and NGC 2264-D. A sharp
velocity discontinuity ~ 2 km/s in amplitude is observed in N_2H+(1-0) and
H^{13}CO+(1-0) in the central, innermost part of NGC 2264-C, which we interpret
as the signature of a strong dynamical interaction between two MMSs and their
possible merging with the central MMS C-MM3. Radiative transfer modelling
supports the idea that NGC 2264-C is a highly unstable prolate clump in the
process of collapsing along its long axis on a near free-fall dynamical
timescale ~ 1.7x10^5 yr. Our model fit of this large-scale collapse suggests a
maximum mass inflow rate ~ 3x10^{-3} Msun/yr toward the central protostellar
object C-MM3. Such infall rates are sufficiently high to overcome radiation
pressure and allow the formation of ~ 20 Msun stars by accretion in ~ 1.7x10^5
yr, i.e., a time similar to the global dynamical timescale of the central part
of NGC 2264-C. We conclude that we are likely witnessing the formation of a
high-mass (> 10 Msun) protostar in the central part of NGC 2264-C. Our results
suggest a picture of massive star formation intermediate between the scenario
of stellar mergers of Bonnell et al. (1998) and the massive turbulent core
model of McKee & Tan (2003).


title: AGN variability time scales and the discrete-event model

abstract:
  We analyse the ultraviolet variability time scales in a sample of 15 Type 1
Active Galactic Nuclei (AGN) observed by IUE. Using a structure function
analysis, we demonstrate the existence in most objects of a maximum variability
time scale of the order of 0.02-1.00 year. We do not find any significant
dependence of these maximum variability time scales on the wavelength, but we
observe a weak correlation with the average luminosity of the objects. We also
observe in several objects the existence of long-term variability, which seems
decoupled from the short-term one. We interpret the existence of a maximum
variability time scale as a possible evidence that the light curves of Type 1
AGN are the result of the superimposition of independent events. In the
framework of the so-called discrete-event model, we study the event energy and
event rate as a function of the object properties. We confront our results to
predictions from existing models based on discrete events. We show that models
based on a fixed event energy, like supernova explosions, can be ruled out. In
their present form, models based on magnetic blobs are also unable to account
for the observed relations. Stellar collision models, while not completely
satisfactory, cannot be excluded.


title:
Observations of Active Galactic Nuclei with Ground-Based Cherenkov
  Telescopes

abstract:
  Imaging Atmospheric Cherenkov Telescopes (IACTs) allow us to observe Active
Galactic Nuclei (AGNs) in the 100 GeV to 20 TeV energy range with high
sensitivity. The TeV gamma-ray observations of the nine blazars detected so far
in this energy range reveal rapid flux and spectral variability on time scales
of several hours, sometimes even on time scales of a few minutes. While simple
synchrotron-Compton models can explain the observed non-thermal emission,
alternative models which involve high-energy protons are not yet ruled out.
After reviewing the status of the major IACT experiments, we describe some
recent observational results and their astrophysical implications. We conclude
with a discussion of possible avenues for future research.


title:
Clearing up the clouds around NGC 4151: evidence of a highly ionized
  absorber

abstract:
  The Seyfert 1 galaxy NGC4151 is characterized by complex X-ray absorption,
well described by a dual absorber, composed of a uniform mildly ionized gas and
a cold system that partially covers the central source. However, in one of the
5 BeppoSAX observations, the spectrum shows two peculiar features. An
absorption feature is detected around 8.5-9 keV with a statistical significance
of 99.96%. This feature can be fitted either with an absorption edge at
E=8.62^{+0.34}_{-0.52} keV with optical depth \tau=0.06\pm0.03 or with an
absorption line with 9.5^{+1.3}_{-0.6} keV, width \sigma=0.95^{+1.2}_{-0.7} keV
and EW= 200 eV. In the first case, we associate the feature to highly ionized
iron at rest, like FeXXII-FeXXIII (E_{rest}=8.4-8.5 keV). In the second case
the feature could be identified with a blend of FeXXV and FeXXVI lines, with an
outflow velocity v \approx (0.09-0.26)c. This spectrum is also characterized by
a substantial reduction of the absorption column density and the covering
fraction of the dual absorber. In particular the column density of the mildly
ionized and cold absorbers is \approx 3-5 times lower than observed in the
other states, and the covering fraction is reduced by \approx 40 per cent. We
propose a possible explanation linking the two properties in terms of a
multi-phase ionized absorber.


title:
Direct comparison of the performance of CZT detectors contacted with
  various metals

abstract:
  Cadmium Zinc Telluride (CZT) achieves excellent spatial resolution and good
energy resolution over the broad energy range from several keV into the MeV
energy range. In this paper we present the results of a systematic study of the
performance of CZT detectors manufacturered by Orbotech (before IMARAD)
depending on surface preparation, contact materials and contact deposition. The
standard Orbotech detectors have the dimension of 2.0 x 2.0 x 0.5 cm. They have
a pixellated In anode with 8 x 8 pixels and a monolithic In cathode. Using the
same CZT substrates several times, we have made a direct comparison of the
performance of different contact materials by replacing the cathode and/or the
anode contacts with several high-workfunction metals. We present the
performance of the detectors and conclude with an overview over our ongoing
detector optimization.


title: On the origin of cold dark matter halo density profiles

abstract:
  N-body simulations predict that CDM halo-assembly occurs in two phases: 1) a
fast accretion phase with a rapidly deepening potential well; and 2) a slow
accretion phase characterised by a gentle addition of mass to the outer halo
with little change in the inner potential well. We demonstrate, using
one-dimensional simulations, that this two-phase accretion leads to CDM halos
of the NFW form and provides physical insight into the properties of the mass
accretion history that influence the final profile. Assuming that the
velocities of CDM particles are effectively isotropised by fluctuations in the
gravitational potential during the fast accretion phase, we show that
gravitational collapse in this phase leads to an inner profile rho(r) ~ r^{-1}.
Slow accretion onto an established potential well leads to an outer profile
with rho(r) ~ r^{-3}. The concentration of a halo is determined by the fraction
of mass that is accreted during the fast accretion phase. Using an ensemble of
realistic mass accretion histories, we show that the model predictions of the
dependence of halo concentration on halo formation time, and hence the
dependence of halo concentration on halo mass, and the distribution of halo
concentrations all match those found in cosmological N-body simulations. Using
a simple analytic model that captures much of the important physics we show
that the inner r^{-1} profile of CDM halos is a natural result of hierarchical
mass assembly with a initial phase of rapid accretion.


title: Lorentz violation as a quantum-gravity signature

abstract:
  Many theoretical approaches to quantum gravity predict the breakdown of
Lorentz symmetry at Planck energies. Kinematical cosmic-ray studies are a
sensitive tool in the search for such effects. This talk discusses the
construction of test dispersion relations for such analyses.


title: Eccentricities of Double Neutron Star Binaries

abstract:
  Recent pulsar surveys have increased the number of observed double neutron
stars (DNS) in our galaxy enough so that observable trends in their properties
are starting to emerge. In particular, it has been noted that the majority of
DNS have eccentricities less than 0.3, which are surprisingly low for binaries
that survive a supernova explosion that we believe imparts a significant kick
to the neutron star. To investigate this trend, we generate many different
theoretical distributions of DNS eccentricities using Monte Carlo population
synthesis methods. We determine which eccentricity distributions are most
consistent with the observed sample of DNS binaries. In agreement with
Chaurasia & Bailes (2005), assuming all double neutron stars are equally as
probable to be discovered as binary pulsars, we find that highly eccentric,
coalescing DNS are less likely to be observed because of their accelerated
orbital evolution due to gravitational wave emission and possible early
mergers. Based on our results for coalescing DNS, we also find that models with
vanishingly or moderately small kicks (sigma < about 50 km/s) are inconsistent
with the current observed sample of such DNS. We discuss the implications of
our conclusions for DNS merger rate estimates of interest to ground-based
gravitational-wave interferometers. We find that, although orbital evolution
due to gravitational radiation affects the eccentricity distribution of the
observed sample, the associated upwards correction factor to merger rate
estimates is rather small (typically 10-40%).