title:
IRAS PSCz v.s. 1.2-Jy Velocity and Density Fields: A Spherical Harmonics
  Comparison

abstract:
  We have used the two IRAS redshift surveys, 1.2-Jy (Fisher et al 1995) and
PSCz (Saunders et al 2000), to model the linear velocity fields within a
redshift of 8,000 km/s and have compared them in redshift space. The two
velocity fields only differ significantly in their monopole components. The
monopole discrepancy cannot be solely ascribed to shot-noise errors and
incomplete sky coverage. The mismatch seems to arise from incompleteness of the
PSCz catalog at fluxes $\le$ 1.2 Jy. The 1.2-Jy and PSCz higher order velocity
multipoles, particularly the dipole and quadrupole components, appear to be
consistent, suggesting that the dipole residuals found by Davis, Nusser and
Willick (1996) when comparing 1.2-Jy and MarkIII velocity fields probably
originates from the MarkIII velocities calibration procedure rather than from
uncertainties in the model velocity field. Our results illustrate the
efficiency of the spherical harmonics decomposition techniques in detecting
possible differences between real and model velocity fields. Similar analyses
shall prove to be very useful in the future to test the reliability of next
generation model velocity fields derived from new redshift catalogs like 2dFGRS
(Colless et al 2001), SDSS (York et al 2000), 6dF and 2MRS.


title:
On the Location and Composition of the Dust in the MCG-6-30-15 Warm
  Absorber

abstract:
  Hubble Space Telescope images of MCG-6-30-15 show a dust lane crossing the
galaxy just below the nucleus. In this paper, we argue that this dust lane is
responsible for the observed reddening of the nuclear emission and the Fe I
edge hinted at in the Chandra spectrum of MCG-6-30-15. We further suggest that
the gas within the dust lane can comprise much of the low ionization component
(i.e., the one contributing the O VII edge) of the observed warm absorber.
Moreover, placing the warm absorbing material at such distances (hundreds of
pc) can account for the small outflow velocities of the low ionization
absorption lines as well as the constancy of the O VIII edge. Photoionization
models of a dusty interstellar gas cloud (with a column appropriate for the
reddening toward MCG-6-30-15) using a toy Seyfert 1 spectral energy
distribution show that it is possible to obtain a significant O VII edge
(\tau~0.2) if the material is ~150 pc from the ionizing source. For
MCG-6-30-15, such a distance is consistent with the observed dust lane. The
current data on MCG-6-30-15 is unable to constrain the dust composition within
the warm absorber. Astronomical silicate is a viable candidate, but there are
indications of a very low O abundance in the dust, which is inconsistent with a
silicate origin. If true, this may indicate that there were repeated cycles of
grain destruction and growth from shocks in the interstellar medium of
MCG-6-30-15. Pure iron grains are an unlikely dust constituent due to the limit
on their abundance in the Galaxy, yet they cannot be ruled out. The high column
densities inferred from the highly ionized zone of the warm absorber implies
that this gas is dust-free.


title:
Variations in the Abundance Pattern of Extremely Metal-poor Stars and
  Nucleosynthesis in Population III Supernovae

abstract:
  We calculate nucleosynthesis in Population (Pop) III supernovae (SNe) and
compare the yields with various abundance patterns of extremely metal-poor
(EMP) stars. We assume that the observed EMP stars are the second generation
stars, which have the metal-abundance patterns of Pop III SNe. Previous
theoretical yields of Pop III SNe cannot explain the trends in the abundance
ratios among iron-peak elements (Mn, Co, Ni, Zn)/Fe as well as the large C/Fe
ratio observed in certain EMP stars with [Fe/H] <~ -2.5. In the present paper,
we show that if we introduce higher explosion energies and mixing-fallback in
the core-collapse SN models of M ~ 20 - 130 Msun, the above abundance features
of both typical and C-rich EMP stars can be much better explained. We suggest
that the abundance patterns of the [Fe/H] ~ -2.5 stars correspond to supernova
yields with normal explosion energies, while those of the carbon un-enhanced
([C/Fe] < 1) stars with [Fe/H] =~ -4 ~ - 3 correspond to high-energy supernova
yields. The abundance patterns of the C-rich ([C/Fe]>~ 2) and low [Fe/H] (=~ -5
\~ -3.5) stars can be explained with the yields of faint SNe that eject little
56Ni as observed in SN1997D. In the supernova-induced star formation model, we
can qualitatively explain why the EMP stars formed by the faint or energetic
supernovae have lower [Fe/H] than the EMP stars formed by normal supernovae. We
also examine how the abundance ratios among iron-peak elements depend on the
electron mole fraction Ye, and conclude that a large explosion energy is still
needed to realize the large Co/Fe and Zn/Fe ratios observed in typical EMP
stars with [Fe/H] <~ -3.5.


title: XMM-Newton Observation of Fe Kalpha emission from a BAL QSO: Mrk 231

abstract:
  We present results from a 20 ksec XMM observation of Mrk 231. EPIC data
reveal strong line emission due to Fe Ka, which has rarely been detected in
this class. The line energy is consistent with an origin in neutral Fe and the
width equivalent to a velocity dispersion ~ 18,000 km/s, thus the line may be
attributed to transmission and/or reflection from a distribution of emitting
clouds. If, instead, the line originates in the accretion disk then the line
strength and flat X-ray continuum support some contribution from reflection,
although the data disfavor a model where the hard X-ray band is purely
reflected X-rays from a disk. Line parameters are similar to those obtained for
the BAL QSO, H1413+117.


title: Cosmological Evolution in 1/R-Gravity Theory

abstract:
  Recently, corrections of the $L(R)$ type to Einstein-Hilbert action that
become important at small curvature are proposed. Those type of models intend
to explain the observed cosmic acceleration without dark energy. We derive the
full Modified Friedmann equation in the Palatini formulation of those modified
gravity model of the $L(R)$ type. Then, we discuss various cosmological
predictions of the Modified Friedmann equation.


title: The formation of helium lines in the spectrum of COM J1740-5340

abstract:
  The He I 5876A absorption line recently discovered in the spectrum of the
companion to the millisecond pulsar PSR J1740-5340 is tentatively attributed to
electron impact excitations due to the irradiation of its atmosphere by
gamma-rays emitted by the pulsar's magnetosphere. Numerical calculations,
similar to those carried out previously for Type Ib SNe, indicate that a pulsar
beam with photon energies ~ 1 MeV gives rise to a 5876A line of the observed
strength if the beam's spin-down conversion efficiency approaches 1%. However,
a significant difficulty for the proposed mechanism is the strength of the
singlet line at 6678A. Compared to the corresponding triplets, singlet lines
are weak because of the loss of excitation when photons emitted in decays to
the ground state ionize hydrogen atoms, an effect absent in the hydrogen-free
atmospheres of Type Ib SNe.


title: Non-Gaussianity of Large-Scale Cosmological Perturbations

abstract:
  Perturbations in a universe with matter and cosmological constant are
computed in terms of the primordial scalar perturbation up to second order. The
calculation is easy -- a generalization of the spherical dust solution. Our
expression might allow accurate measurements of the primordial non-Gaussianity.


title:
Optical-Infrared ANDICAM Observations of the Transient Associated with
  GRB 030329

abstract:
  We present photometry of the transient associated with GRB 030329 obtained
with the CTIO 1.3--meter telescope and the ANDICAM instrument, a dual
optical/infrared imager with a dichroic centered at one micron. Without the
need for light curve interpolation to produce snapshot broadband spectra, we
show that the transient spectrum remained statistically achromatic from day 2.7
to day 5.6, during a re-brightening episode. Associating the light in these
early epochs with the GRB afterglow, we infer a modest level of extinction due
to the host galaxy in the line--of--sight toward the GRB: A_V(host) = 0.30 +/-
0.03 mag for beta = -0.5 and A_V(host) < 0.4 mag (3 sigma) for any physically
plausible value of beta (with flux f_nu ~ lambda^-beta). We conclude that the
spectral slope of the afterglow component was more than beta = -0.8 between day
2.7-5.6 after the GRB, excluding the possibility that the synchrotron cooling
break passed through the optical/IR bandpass over that period. Taking
extinction into account, a decomposition of the light curve into an afterglow
and supernova component requires the presence of a supernova similar to that of
SN 1998bw, an afterglow that shows some evidence for a second break around day
8-10, and a fifth re-brightening event around day 15. Assuming an SN
1988bw-like evolution and a contemporaneous GRB and SN event, the peak SN
brightness was M_V = -19.8 +/- 0.4 - 5 log h_65 mag.


title: Non-linear resonance in the accretion disk of a millisecond pulsar

abstract:
  Twin quasi-periodic millisecond modulations of the X-ray flux (kHz QPOs) have
recently been reported from an accreting 2.5 ms X-ray pulsar. We identify modes
of disk oscillations whose frequencies are in agreement with the observed ones
when the rotating neutron star is modeled with realistic equations of state.
The frequency difference of the twin QPOs, equal to about one half of the
neutron-star spin rate, clearly indicates that resonant oscillations of the
accretion disk have been observed. Similar non-linear resonances may also be
spontaneously excited in the accretion disk. The two QPO frequencies in the
pulsar system are close to a 5:7 ratio and this suggests a link with the QPOs
in black hole systems, where frequency ratios of 2:3 and 3:5 have been
reported.


title: Do X-ray Binary Spectral State Transition Luminosities Vary?

abstract:
  We tabulate the luminosities of the soft-to-hard state transitions of all
X-ray binaries for which there exist good X-ray flux measurements at the time
of the transition, good distance estimates, and good mass estimates for the
compact star. We show that the state transition luminosities are at about 1-4%
of the Eddington rate, markedly smaller than those typically quoted in the
literature, with a mean value of 2%. Only the black hole candidate GRO
J~1655-40 and the neutron star systems Aql X-1 and 4U 1728-34 have measured
state transition luminosities inconsistent with this value at the 1$\sigma$
level. GRO J~1655-40, in particular, shows a state transition luminosity below
the mean value for the other sources at the $4\sigma$ level. This result,
combined with the known inner disk inclination angle (the disk is nearly
parallel to the line of sight) from GRO J~1655-40's relativistic jets suggest
that the hard X-ray emitting region in GRO J~1655-40 can have a velocity of no
more than about $\beta=0.68$, with a most likely value of about $\beta=0.52$,
and a minimum speed of $\beta=0.45$, assuming that the variations in state
transition luminosities are solely due to relativistic beaming effects. The
variance in the state transition luminosities suggests an emission region with
a velocity of $\sim0.2c$. The results are discussed in terms of different
emission models for the low/hard state. We also discuss the implications for
measuring the dimensionless viscosity parameter $\alpha$. We also find that if
its state transitions occur at typical luminosities, then GX 339-4 is likely to
be at a distance of at least 7.6 kpc, much further than typically quoted
estimates.


title:
CHANDRA observations of the NGC 1550 galaxy group -- implication for the
  temperature and entropy profiles of 1 keV galaxy groups

abstract:
  We present a detailed \chandra study of the galaxy group NGC 1550. For its
temperature (1.37$\pm$0.01 keV) and velocity dispersion ($\sim$ 300 km
s$^{-1}$), the NGC 1550 group is one of the most luminous known galaxy groups
(L$_{\rm bol}$ = 1.65$\times10^{43}$ erg s$^{-1}$ within 200 kpc, or 0.2 \rv).
We find that within $\sim 60$ kpc, where the gas cooling time is less than a
Hubble time, the gas temperature decreases continuously toward the center,
implying the existence of a cooling core. The temperature also declines beyond
$\sim$ 100 kpc (or 0.1 \rv). There is a remarkable similarity of the
temperature profile of NGC 1550 with those of two other 1 keV groups with
accurate temperature determination. The temperature begins to decline at 0.07 -
0.1 \rv, while in hot clusters the decline begins at or beyond 0.2 \rv. Thus,
there are at least some 1 keV groups that have significantly different
temperature profiles from those of hot clusters, which may reflect the role of
non-gravitational processes in ICM/IGM evolution. NGC 1550 has no isentropic
core in its entropy profile, in contrast to the predictions of `entropy-floor'
simulations. We compare the scaled entropy profiles of three 1 keV groups
(including NGC 1550) and three 2 - 3 keV groups. The scaled entropy profiles of
1 keV groups show much larger scatter than those of hotter systems, which
implies varied pre-heating levels. We also discuss the mass content of the NGC
1550 group and the abundance profile of heavy elements.


title:
First INTEGRAL Observations of Eight Persistent Neutron Star Low Mass
  X-ray Binaries

abstract:
  Early results from the INTEGRAL Core Program, for a sample of eight
persistently bright neutron star low mass X-ray binaries in the energy range
from 5 keV to 200 keV are presented. It is shown that INTEGRAL efficiently
detects sources and that spectra may be obtained up to several hundreds of keV
by combining data from three of the four INTEGRAL instruments: JEM-X, IBIS and
SPI. For the source GX 17+2 it is shown that the spectrum extends well above
100 keV with a flattening of the spectrum above 30 keV. This might suggest a
non-thermal comptonisation emission, but uncertainties in the current data
reduction and background determination do not allow firm conclusions to be
drawn.


title:
The Origin of Jovian Planets in Protostellar Disks: The Role of Dead
  Zones

abstract:
  The final masses of Jovian planets are attained when the tidal torques that
they exert on their surrounding protostellar disks are sufficient to open gaps
in the face of disk viscosity, thereby shutting off any further accretion. In
sufficiently well-ionized disks, the predominant form of disk viscosity
originates from the Magneto-Rotational Instability (MRI) that drives
hydromagnetic disk turbulence. In the region of sufficiently low ionization
rate -- the so-called dead zone -- turbulence is damped and we show that lower
mass planets will be formed. We considered three ionization sources (X-rays,
cosmic rays, and radioactive elements) and determined the size of a dead zone
for the total ionization rate by using a radiative, hydrostatic equilibrium
disk model developed by Chiang et al. (2001). We studied a range of surface
mass density (Sigma_{0}=10^3 - 10^5 g cm^{-2}) and X-ray energy (kT_{x}=1 - 10
keV). We also compared the ionization rate of such a disk by X-rays with cosmic
rays and find that the latter dominate X-rays in ionizing protostellar disks
unless the X-ray energy is very high (5 - 10 keV). Among our major conclusions
are that for typical conditions, dead zones encompass a region extending out to
several AU -- the region in which terrestrial planets are found in our solar
system. Our results suggest that the division between low and high mass planets
in exosolar planetary systems is a consequence of the presence of a dead zone
in their natal protoplanetary disks. We also find that the extent of a dead
zone is mainly dependent on the disk's surface mass density. Our results
provide further support for the idea that Jovian planets in exosolar systems
must have migrated substantially inwards from their points of origin.


title: The Central Engines of Radio-Loud Quasars

abstract:
  We have assembled a sample of 37 RLQs that have been imaged with the HST in
order to investigate their black hole masses, accretion rates, and the
structure of their accretion disks. The black hole masses were estimated from
the luminosities of the host galaxies, and the accretion powers were
extrapolated from the emission-line luminosities. The majority of the quasars
have masses in the range $M_{\rm BH} \approx 10^8-10^9$ solar mass. Their
accretion rates, $\dot M \approx 0.01-1$ times the Eddington rate, suggest that
most of the objects possess standard optically thick, geometrically thin
accretion disks, in some cases perhaps accompanied by an optically thin
advection-dominated component. The coexistence of strong radio emission and a
standard disk conflicts with recent models for jet formation. We discuss
modifications of the standard model that can resolve this discrepancy. We find
there is a strong correlation between the accretion rate and the extended radio
luminosity. This lends support to the idea that the extended radio emission is
somehow linked to the accretion disk. Lastly, we combine the present sample of
radio-loud quasars with the sample of BL Lac objects to reevaluate the
unification picture for radio-loud AGNs. Consistent with current ideas for the
unification of radio-loud sources, we find that flat-spectrum radio quasars and
FR II radio galaxies indeed seem to belong to the same population, as do BL
Lacs and FR I radio galaxies on the opposite end of the luminosity spectrum.
However, some members of the low frequency-peaked BL Lac objects may be more
closely associated with FR II rather than FR I radio galaxies. We describe how
the various subclasses of radio-loud sources can be viewed as a continuous
sequence of varying accretion rate.


title: Investigating lensing by absorbers in the 2dF-Quasar survey

abstract:
  We use the first data release of the 2-degree Field Quasar survey to
investigate the effect of gravitational magnification by foreground absorbing
systems on background quasars. We select two populations of quasars from this
sample: one with strong MgII/FeII absorbers and one without. The selection is
done in such a way that the two populations have the same redshift distribution
and the absorber detection procedure discards possible biases with quasar
magnitude. We then compare their magnitude distributions and find a relative
excess of bright quasars with absorbers. This effect is detected at the 2.4,
3.7 and 4.4 sigma levels in u-, b- and r-bands. Various explanations of the
observed phenomenon are considered and several lines of evidence point towards
gravitational lensing causing some of the differences observed in the magnitude
distributions. We note that physical quasar-absorber associations may
contribute to some extent to the observed correlations for low quasar-absorber
velocity differences. We discuss the implications of these findings and propose
future work which will allow us to strengthen and extend the results presented
here.


title: Photoionization Feedback in Low--Mass Galaxies at High Redshift

abstract:
  The cosmic ultraviolet (UV) ionizing background impacts the formation of
dwarf galaxies in the low-redshift universe (z=3) by suppressing gas infall
into galactic halos with circular velocities up to v(circ)=75 km/s. Using a
one-dimensional, spherically symmetric hydrodynamics code (Thoul & Weinberg
1995), we examine the effect of an ionizing background on low-mass galaxies
forming at high redshifts (z>10). We find that the importance of
photoionization feedback is greatly reduced, because (1) at high redshift,
dwarf-galaxy sized objects can self-shield against the ionizing background, (2)
collisional cooling processes at high redshift are more efficient, (3) the
amplitude of the ionizing background at high redshift is lower, and (4) the
ionizing radiation turns on when the perturbation that will become the dwarf
galaxy has already grown to a substantial overdensity. We find that because of
these reasons, gas can collect inside halos with circular velocities as low as
v(circ)=10 km/s. This result has important implications for the reionization
history of the universe.


title: Millimeter VLBI and Variability in AGN Jets

abstract:
  Millimeter-VLBI images probe as deep as never before the nuclei of AGN.
Global 3mm-VLBI where the VLBA is combined with sensitive European stations,
gives CLEAN maps of a quality, which never before was so good. VLBI at 147 GHz
yields transatlantic fringes for the first time. Now it will become possible to
study the relation between jet kinematics and spectral activity with a few ten
micro-arcsecond resolution at the shortest wavelengths.


title: Millimeter-VLBI with a Large Millimeter-Array: Future Possibilities

abstract:
  We discuss possibilities and improvements which could be obtained, if a
phased array with a large number (N=50-100) of sub-millimeter antennas - like
the planned large southern array (the former LSA, now ALMA) is used for
radio-interferometry with very long baselines (VLBI) at millimeter wavelengths.
We find that the inclusion of such an instrument in global VLBI network will
push the sensitivity and the imaging capabilities of high resolution millimeter
interferometry by up to 2 orders of magnitude. This will cause many but todate
unforseeable new discoveries.


title:
Unveiling the Nature of the 321 s Modulation in RX J0806.3+1527:
  Near-Simultaneous Chandra and VLT Observations

abstract:
  We report on the first near-simultaneous X-ray and optical observations of RX
J0806.3+1527. The source is believed to be a 321s orbital period ultra-compact
binary system hosting an X-ray emitting white dwarf. Data were obtained with
Chandra and the ESO Very Large Telescope (VLT) in November 2001. We found an
optical/X-ray phase-shift in the periodic modulation of about 0.5, strongly
favoring the existance of two distinct emission regions in the two bands (for
the pulsed fluxes). The Chandra data allow us to study, for the first time, the
spectral continuum of RX J0806.3+1527 in soft X-rays. This was well fitted by a
blackbody spectrum with kT about 65eV and hydrogen column density of N_H about
5 x 10^20 cm^-2. The average (unabsorbed) source 0.1-2.5 keV luminosity during
the modulation-on is L_X about 5 x 10^32 erg s^-1 (assuming a distance of
500pc). Such a value is lower than the luminosity expected if stable mass
transfer between two white dwarfs were driven by gravitational radiation.
Evidence for absorption-like features are present in the phase-averaged
spectrum at about 0.53, 0.64, and 1.26 keV, which may be attributed to heavy
elements (C and N). We compare and discuss these findings with other binary
systems hosting an accreting white dwarf.


title: Constraints on intergalactic dust from quasar colours

abstract:
  Colour measurements of quasars are used to constrain the abundance and
properties of intergalactic dust and the related extinction effects on high-z
sources. For Type Ia supernovae at z = 1, we derive an upper limit on the
possible dimming from intergalactic dust of dm=0.2, ruling out the ``grey''
dust scenario as being solely responsible for the observed faintness of high-z
SNIa.


title: The INTEGRAL Science Data Centre (ISDC)

abstract:
  The INTEGRAL Science Data Centre (ISDC) provides the INTEGRAL data and means
to analyse them to the scientific community. The ISDC runs a gamma ray burst
alert system that provides the position of gamma ray bursts on the sky within
seconds to the community. It operates a quick-look analysis of the data within
few hours that detects new and unexpected sources as well as it monitors the
instruments. The ISDC processes the data through a standard analysis the
results of which are provided to the observers together with their data.


title:
Detection of elements beyond the Ba-peak in VLT+UVES spectra of post-AGB
  stars

abstract:
  In this letter, we report on our successful systematic search for lines of
elements beyond the Ba-peak in spectra of s-process enriched post-AGB stars.
Using newly released atomic data from both the VALD database and the D.R.E.A.M.
project, we could derive abundances for several elements heavier than europium
for three objects, on the base of high quality VLT+UVES spectra. The abundances
of these elements are of particular interest since they turn out to be powerful
constraints for chemical evolutionary AGB models. Their high abundances
indicate that, also in only moderately metal deficient AGB stars, production of
lead is expected to be significant.


title: Principal Power of the CMB

abstract:
  We study the physical limitations placed on CMB temperature and polarization
measurements of the initial power spectrum by geometric projection, acoustic
physics, gravitational lensing and the joint fitting of cosmological
parameters. Detailed information on the spectrum is greatly assisted by
polarization information and localized to the acoustic regime k = 0.02-0.2
Mpc^{-1} with a fundamental resolution of Delta k/k>0.05. From this study we
construct principal component based statistics, which are orthogonal to
cosmological parameters including the initial amplitude and tilt of the
spectrum, that best probe deviations from scale-free initial conditions. These
statistics resemble Fourier modes confined to the acoustic regime and
ultimately can yield ~50 independent measurements of the power spectrum
features to percent level precision. They are straightforwardly related to more
traditional parameterizations such as the the running of the tilt and in the
future can provide many statistically independent measurements of it for
consistency checks. Though we mainly consider physical limitations on the
measurements, these techniques can be readily adapted to include instrumental
limitations or other sources of power spectrum information.


title: The Globular Cluster System of the Spiral Galaxy NGC7814

abstract:
  We present the results of a wide-field photometric study of the globular
cluster (GC) system of the edge-on Sab spiral NGC7814. This is the first spiral
to be fully analyzed from our survey of the GC systems of a large sample of
galaxies beyond the Local Group. NGC7814 is of particular interest because a
previous study estimated that it has 500-1000 GCs, giving it the largest
specific frequency (S_N) known for a spiral. Understanding this galaxy's GC
system is important in terms of our understanding of the GC populations of
spirals in general and has implications for the formation of massive galaxies.
We observed the galaxy in BVR filters with the WIYN 3.5-m telescope, and used
image classification and three-color photometry to select GC candidates. We
also analyzed archival HST WFPC2 images of NGC7814, both to help quantify the
contamination level of the WIYN GC candidate list and to detect GCs in the
inner part of the galaxy halo. Combining HST data with high-quality
ground-based images allows us to trace the entire radial extent of this
galaxy's GC system and determine the total number of GCs directly through
observation. We find that rather than being an especially high-S_N spiral,
NGC7814 has <200 GCs and S_N ~ 1, making it comparable to the two most
well-studied spirals, the Milky Way and M31. We explore the implications of
these results for models of the formation of galaxies and their GC systems. The
initial results from our survey suggest that the GC systems of typical
ellipticals can be accounted for by the merger of two or more spirals, but that
for highly-luminous ellipticals, additional physical processes may be needed.


title:
Interferometric Mapping of Magnetic Fields in Star-forming Regions III.
  Dust and CO polarization in DR21(OH)

abstract:
  We present the polarization detections in DR21(OH) from both the thermal dust
emission at 1.3 mm and the CO J=2-1 line obtained with the
Berkeley-Illinois-Maryland Association (BIMA) array. Our results are consistent
with the prediction of the Goldreich-Kylafis effect that the CO polarization is
either parallel or perpendicular to the magnetic field direction. The detection
of the polarized CO emission is over a more extended region than the dust
polarization, while the dust polarization provides an aide in resolving the
ambiguity of the CO polarization. The combined results suggest that the
magnetic field direction in DR21(OH) is parallel to the CO polarization and
therefore parallel to the major axis of DR21(OH). The strong correlation
between the CO and dust polarization suggests that magnetic fields are
remarkably uniform throughout the envelope and the cores. The dispersion in
polarization position angles implies a magnetic field strength in the plane of
the sky of about 1 mG, compared with about 0.5 mG inferred for the
line-of-sight field from previous CN Zeeman observations. Our CO data also show
that both MM1 and MM2 power high-velocity outflows with $v\gtrsim$25 km/s
relative to the systematic velocity.


title: NIR surface photometry of a sample of nearby spiral galaxies

abstract:
  The first results of an observational programme aimed at mapping a sample of
face--on spiral galaxies in the NIR are presented. This paper shows the surface
photometry of the first ten galaxies in the sample. The data were taken in the
broad band $J$ (1.2 $\mu$m) and $K_{s}$ (2.2 $\mu$m) filters. The sources were
selected mainly according to their size and brightness in order to suit the
characteristics of the CAIN 2D NIR camera on the 1.5 m Carlos S\'anchez
Telescope (Tenerife, Spain). The primary scientific goal is to provide a
comprehensive and uniform database of the main structural and photometric
parameters of the sample members from NIR surface photometry. To this end,
elliptical isophotal fitting was performed on each galaxy image to extract
information about the size and location of its morphological components and
provide the azimuthally averaged radial brightness profile. Analytical
functions for each component's brightness distribution were then used to match
that profile, and their functional parameters obtained from the global fitting.
This first report includes data for NGC 3344, NGC 3686, NGC 3938, NGC 3953, NGC
4254, NGC 4303, NGC 4314, NGC 5248, NGC 6384 and NGC 7479.


title: The Halo Occupation Number and Spatial Distribution of 2dF Galaxies

abstract:
  We use the clustering results obtained by Madgwick et al. (2003) for a sample
of 96,791 2dF galaxies with redshift 0.01 < z < 0.15 to study the distribution
of late-type and early-type galaxies within dark matter haloes of different
mass. The adopted method relies on the connection between the distribution of
sources within haloes and their clustering properties by focussing on the issue
of the halo occupation function i.e. the probability distribution of the number
of galaxies brighter than some luminosity threshold hosted by a virialized halo
of given mass. Within this framework, the distribution of galaxies within
haloes is shown to determine galaxy-galaxy clustering on small scales, being
responsible for the observed power-law behaviour at separations r < 3 Mpc. For
a more extended analysis, we refer the reader to Magliocchetti & Porciani
(2003)


title: On the Interpretation Of the Local Dark Matter

abstract:
  The cause of the extended rotation curves of galaxies is investigated. It is
shown that conventional sources and most exotic sources for the needed
gravitational fields are implausible. We suggest spatial fluctuations in a
scalar field, similar to the inflation field, are responsible for the
gravitational fields. These fluctuations play the role of `dark' halos around
galaxies. They take $\sim 10^5$ yrs to develop and could not have been
important in the early days of the universe. When galaxies are clustered, a
$\Lambda-$term appears naturally in this theory. The universe's present energy
density associated with these scalar field ariations is $\Omega \sim 1/2-2/3$.
A possible scenario is uggested in which the cosmic scale factor ${\cal R}(t)$
would have experienced a recent acceleration. A discussion of further
observations and theoretical work needed to resolve some ambiguities in the
theory is given.


title:
Orbital Migration and Mass Accretion of Protoplanets in 3D Global
  Computations with Nested Grids

abstract:
  We investigate the evolution of protoplanets with different masses embedded
in an accretion disk, via global fully three-dimensional hydrodynamical
simulations. We consider a range of planetary masses extending from one and a
half Earth's masses up to one Jupiter's mass, and we take into account
physically realistic gravitational potentials of forming planets. In order to
calculate accurately the gravitational torques exerted by disk material and to
investigate the accretion process onto the planet, the flow dynamics has to be
thoroughly resolved on long as well as short length scales. We achieve this
strict resolution requirement by applying a nested-grid refinement technique
which allows to greatly enhance the local resolution. Our results from
altogether 51 simulations show that for large planetary masses, approximately
above a tenth of the Jupiter's mass, migration rates are relatively constant,
as expected in type II migration regime and in good agreement with previous
two-dimensional calculations. In a range between seven and fifteen Earth's
masses, we find a dependency of the migration speed on the planetary mass that
yields time scales considerably longer than those predicted by linear
analytical theories. This property may be important in determining the overall
orbital evolution of protoplanets. The growth time scale is minimum around
twenty Earth-masses, but it rapidly increases for both smaller and larger mass
values. Significant differences between two- and three-dimensional calculations
are found in particular for objects with masses smaller than ten Earth-masses.
We also derive an analytical approximation for the numerically computed mass
growth rates.


title:
The Lenses Structure & Dynamics Survey: The internal structure and
  evolution of E/S0 galaxies and the determination of H_0 from time-delay
  systems

abstract:
  The Lenses Structure & Dynamics (LSD) Survey aims at studying the internal
structure of luminous and dark matter - as well as their evolution - of field
early-type (E/SO) galaxies to z~1. In particular, E/S0 lens galaxies are
studied by combining gravitational lensing, photometric and kinematic data
obtained with ground-based (VLA/Keck/VLT) and space-based telescopes (HST).
Here, we report on preliminary results from the LSD Survey, in particular on
(i) the constraints set on the luminous and dark-matter distributions in the
inner several R_eff of E/S0 galaxies, (ii) the evolution of their stellar
component and (iii) the constraints set on the value of H_0 from time-delay
systems by combining lensing and kinematic data to break degeneracies in
gravitational-lens models.


title:
A Method for Black Hole Mass Determination in Accretion Powered X-Ray
  Sources

abstract:
  We describe a method for the determination of black-hole masses based on
information inferred from high-energy spectra. It is required that the spectral
energy distribution consist of thermal and Comptonized components. One can
then, in principle, infer the depth of the gravitational potential well for
sources of known distance. The thermal component is inferred by the integration
of a blackbody spectral form over the disk. We assume that the color
temperature distribution in the disk has a specific shape given by the
Shakura-Sunyaev (1973) disk model which goes to zero at the inner disk radius
and at infinity and has a maximum at 4.2 Schwarzchild radii. In this
formulation there is only one parameter, the so called color correction factor,
relating the apparent temperature to effective temperature which characterizes
the thermal emission component. We have made use of improved Galactic black
hole binary dynamical mass determinations to derive, in effect, an empirical
calibration of this factor. We then present our analysis of observational data
for representative objects of several classes; Galactic black hole X-ray
binaries, narrow line Seyfert galaxies (NLS1), and ``ultra-luminous''
extragalactic X-ray sources (ULX). We then apply our mass determination
calculation and present our results. We argue that this approach can
potentially fill a void in the current knowledge of NLS1 and ULX properties,
and discuss how a deeper understanding of both classes has relevance to the
broader issues of how cosmic black holes, beyond the stellar-mass realm, are
formed and what is their overall mass distribution.


title:
Far UV Spectra of Fast Coronal Mass Ejections Associated with X-class
  Flares

abstract:
  The Ultraviolet Coronagraph Spectrometer (UVCS) aboard the {\it SOHO}
satellite has observed very fast Coronal Mass Ejections (CMEs) associated with
X-class flares. These events show spectral signatures different than those seen
in most other CMEs in terms of very rapid disruption of the pre-CME streamer,
very high Doppler shifts and high temperature plasma visible in the [Fe XVIII]
emission line. This paper describes three very similar events on 21 April, 23
July and 24 August 2002 associated with X-class flares. We determine the
physical parameters of the pre-CME streamers and discuss the geometrical and
physical nature of the streamer blowouts. In the 21 April event, the hot plasma
seen as [Fe XVIII] is not related to the structure seen in [Fe XXI] by SUMER at
lower heights. It has the form of a rapidly expanding fan, quite likely a
current sheet. In the August event, on the other hand, the [Fe XVIII] is
probably a bubble of hot plasma formed by reconnection in the wake of the CME.
C III emission from the July 23 flare is detected as stray light in the UVCS
aperture. It precedes the hard X-ray brightening by about 2 minutes.


title:
The Origin of X-shaped Radio Galaxies: Clues from the Z-symmetric
  Secondary Lobes

abstract:
  Existing radio images of a few X-shaped radio galaxies reveal Z-symmetric
morphologies in their weaker secondary lobes which cannot be naturally
explained by either the galactic merger or radio-lobe backflow scenarios, the
two dominant models for these X-shaped radio sources. We show that the merger
picture can explain these morphologies provided one takes into account that,
prior to the coalescence of their supermassive black holes, the smaller galaxy
releases significant amounts of gas into the ISM of the dominant active galaxy.
This rotating gas, whose angular momentum axis will typically not be aligned
with the original jets, is likely to provide sufficient ram pressure at a
distance ~10 kpc from the nucleus to bend the extant jets emerging from the
central engine, thus producing a Z-symmetry in the pair of radio lobes. Once
the two black holes have coalesced some 10^7 yr later, a rapid reorientation of
the jets along a direction close to that of the orbital angular momentum of the
swallowed galaxy relative to the primary galaxy would create the younger
primary lobes of the X-shaped radio galaxy. This picture naturally explains why
such sources typically have powers close to the FR I/II break. We suggest that
purely Z-symmetric radio sources are often en route to coalescence and the
concomitant emission of substantial gravitational radiation, while X-shaped
ones have already merged and radiated.


title: SMC-Type Interstellar Dust in the Milky Way

abstract:
  It is well known that the sightline toward HD 204827 in the cluster Trumpler
37 shows an UV extinction curve that does not follow CCM. However, when a dust
component, foreground to the cluster, is removed, the residual extinction curve
is identical to that found in the SMC within the uncertainties. The curve is
very steep and has little or no 2175 A bump. The position of HD 204827 in the
sky is projected onto the edge of the Cepheus IRAS Bubble. In addition, HD
204827 has an IRAS bowshock indicating that it may be embedded in dust swept up
by the supernova that created the IRAS Bubble. Shocks due to the supernova may
have led to substantial processing of this dust. The HD 204827 cloud is dense
and rich in carbon molecules. The 3.4 $\mu$m feature indicating a C-H grain
mantle is present in the dust toward HD 204827. The environment of the HD
204827 cloud dust may be similar to the dust associated with HD 62542 which
lies on the edge of a stellar wind bubble and is also dense and rich in
molecules. This sightline may be a Rosetta Stone if its environment can be
related to those in the SMC having similar dust.


title: X-ray flashes from off-axis nonuniform jets

abstract:
  It is widely believed that outflows of gamma-ray bursts are jetted. Some
people also suggest that the jets may have structures like
$\epsilon(\theta)\propto\theta^{-k}$. We test the possibility of X-ray flashes
coming from such jets in this paper. Both qualitative and quantitative analyses
have shown that this model can reproduce most observational features for both
X-ray flashes and gamma-ray bursts. Using common parameters of gamma-ray
bursts, we have done both uniform and nonuniform jets' numerical calculations
for their fluxes, spectra and peak energies. It seems that nonuniform jets are
more appropriated to these observational properties than uniform ones. We also
give a spectrum and flux fit to the most significant X-ray flash, XRF971019 by
our model. We also have shown that in our model the observational ratio of
gamma-ray bursts to X-ray flashes is about several.


title: Infrared Spectroscopy of 15 Radio Galaxies at 2<z<2.6

abstract:
  Near-infrared spectra of 15 high-redshift radio galaxies (HzRGs) located at
$2<z<2.6$ were obtained by the OH Airglow Suppressor spectrograph mounted on
the Subaru telescope. The UV-optical line ratio diagnostic diagrams indicate
that half of the observed HzRGs have extended emission-line regions with low
metal abundance, photoionized by a flat-continuum active galactic nucleus such
as a quasar. We also found two probable correlations between radio and
rest-optical parameters: (1) HzRGs with massive hosts tend to have a redder
rest-optical continuum, and (2) HzRGs with smaller radio sizes also show a
redder optical continuum. On the basis of the correlations, the nature of HzRGs
at $2<z<2.6$ is discussed.


title:
Axisymmetric stability criterion for two gravitationally coupled
  singular isothermal discs

abstract:
  Using the two-fluid formalism with the polytropic approximation, we examine
the axisymmetric stability criterion for a composite system of gravitationally
coupled stellar and gaseous singular isothermal discs (SIDs).


title: Dusty ERO Search behind Two Massive Clusters

abstract:
  We performed deep K'-band imaging observations of 2 massive clusters, MS
0451.6-0305 at z = 0.55 and MS 0440.5+0204 at z = 0.19, for searching
counterparts of the faint sub-mm sources behind these clusters, which would
provide one of the deepest extremely red object(ERO) samples. Comparing our
near-infrared images with optical images taken by the Hubble Space Telescope
and by the Subaru Telescope, we identified 13 EROs in these fields. The sky
distributions of EROs are consistent with the previous results, that there is a
sign of strong clustering among detected EROs. Also, the surface density with
corrected lensing amplification factors in both clusters are in good agreement
with that derived from previous surveys. We found 7 EROs and 3 additional very
red objects in a small area (\sim 0.6 arcmin^2) of the MS 0451.6-0305 field
around an extended SCUBA source. Many of their optical and near-infrared colors
are consistent with dusty star-forming galaxies at high redshifts(z \sim
1.0-4.0), and they may be constituting a cluster of dusty starburst galaxies
and/or lensed star-forming galaxies at high redshift. Their red J-K' colors and
faint optical magnitudes suggest they are relatively old massive stellar
systems with ages(>300 Mega years) suffering from dust obscuration. We also
found a surface-density enhancement of EROs around the SCUBA source in the MS
0440.5+0204 field.


title:
A limit cycle model for long-term optical variations of V Sagittae: The
  second example of accretion wind evolution

abstract:
  V Sagittae shows quasi-periodic optical high (soft X-ray off) and low (soft
X-ray on) states with the total period of ~300 days. A binary model is
presented to explain orbital light curves both for the high and low states as
well as the transition mechanism between them. The binary model consists of a
white dwarf (WD), a disk around the WD, and a lobe-filling main-sequence (MS)
companion. In the optical high state, the mass transfer rate to the WD exceeds
the critical rate of ~1 x 10^{-6} Msun/yr, and the WD blows an optically thick,
massive wind. Surface layers of the disk are blown in the wind and the disk
surface extends to the companion or over. As a result, optical luminosity of
the disk increases by a magnitude because of its large irradiation effect. The
massive wind completely obscures soft X-rays. This corresponds to the optical
high/soft X-ray off state. The transition between optical high and low states
is driven by an attenuation of the mass transfer from the secondary. As the
mass supply stops, the WD wind weakens and eventually stops. The disk shrinks
to a Roche lobe size and the optical magnitude drops. This phase corresponds to
the optical low/soft X-ray on state. This cycle is repeated like a limit cycle.
The WD can grow in mass at the critical rate and eventually reach the
Chandrasekhar mass limit. This process is called ``accretion wind evolution,''
which is a key evolutionary process in a recently developed evolutionary
scenario of Type Ia supernovae. This evolutionary process was first confirmed
in the LMC supersoft X-ray source RX J0513.9$-$6951. Thus, V Sge is the second
example of accretion wind evolution.


title:
Optical Identification of the ASCA Lynx Deep Survey: An Association of
  QSOs and a Supercluster at z=1.3?

abstract:
  Results of optical identification of the ASCA Lynx deep survey are presented.
Six X-ray sources are detected in the 2-7 keV band using the SIS in a 20'x20'
field of view with fluxes larger than ~4x10^{-14} erg s-1 cm-2 in the band.
Follow-up optical spectroscopic observations were made, and five out of six
sources are identified with AGNs/QSOs at redshifts of 0.5-1.3. We also identify
two more additional X-ray sources detected in a soft X-ray band with AGNs/QSOs.
It is found that three QSOs identified are located at z~1.3. Two rich clusters
and several groups of galaxies are also placed at the same redshift in the
surveyed field, and projected separations between the QSOs and the clusters are
3-8 Mpc at the redshift.


title:
Stellar yields with rotation and their effect on chemical evolution
  models

abstract:
  We compute the evolution of different abundance ratios in the Milky Way (MW)
for two different sets of stellar yields. In one of them stellar rotation is
taken into account and we investigate its effects on the chemical evolution
model predictions. Moreover, we show that some abundance ratios offer an
important tool to investigate the halo-disk discontinuity. For the first time
it is shown that the effect of a halt in the star formation between the
halo/thick disk and thin disk phases, already suggested from studies based both
on Fe/O vs. O/H and Fe/Mg vs. Mg/H, should also be seen in a C/O versus O/H
plot if C is produced mainly by low- and intermediate-mass stars (LIMS). The
idea that C originates mainly from LIMS is suggested by the flat behavior of
the [C/Fe] ratio as a function of metallicity, from [Fe/H]=-2.2 to solar, and
by the fact that very recent C/O measurements for stars in the MW halo and disk
seem to show a discontinuity around log(O/H)+12=8.4. Finally, a more gentle
increase of N abundance with metallicity (or time), relative to models adopting
the yields of van den Hoek and Groenewegen (1997), is predicted by using the
stellar yields of Meynet and Maeder (2002 - which include stellar rotation but
not hot-bottom burning) for intermediate mass stars. This fact has some
implications for the timescales of N enrichment and thus for the interpretation
of the nature of Damped Lyman Alpha Systems.


title: Conspirative cosmology with variable constants

abstract:
  We have investigated a cosmological model with variable speed of light (c),
gravitational constant (G) and cosmological constant (Lambda). The model is
shown to solve the horizon, flatness and monopole problems of the early
universe. We have found that with a certain variation of these parameters the
model predicts a cosmic acceleration. The model also predicts that for a flat
universe Lambda vanishes in both radiation and matter phases. If the
gravitational constant is allowed to increase then we might not need the
existence of dark matter.


title: Gamma-ray sources at high latitudes (Extragalactic gamma-ray sources)

abstract:
  This Chapter provides a review of $\gamma$-ray sources lying at high Galactic
latitudes. Their statistical properties and variability status, as well as
studies involving cross correlations with lower frequency catalogs and
multiwavelength observations, are summarized. The case for active galactic
nuclei is analyzed with special emphasis, since they represent the largest
population of high energy sources known to date. Other potential $\gamma$-ray
emitters (including nearby starburst galaxies, normal galaxies, molecular
clouds in the Galactic halo, galaxy clusters, and radio galaxies) that may
appear in the next generation of $\gamma$-ray catalogs and, perhaps, that might
have been already observed by EGRET as unidentified detections, are discussed.


title: The Infrared-X-ray continuum correlation in Active Galactic Nuclei

abstract:
  The correlation between the soft X-ray and near infrared emission from AGN is
analysed using composite models by the code SUMA. We find new evidences for
differences in ranges of parameters which characterize the NLR of Seyfert
galaxies and LINERs. Results obtained by modelling the Einstein and the ROSAT
samples of galaxies are in full agreement. In order to fit the infrared and
X-ray continua, an eta factor is defined, which accounts for the emitting area
of the cloud. If the infrared emission is due to bremsstrahlung and comes from
the same cloud producing the soft X-rays, the eta values obtained from both
emissions must be the same. Therefore, if eta_IR < eta_soft-X there must be a
strong contribution of soft X-rays from the active centre. From the eta values
we expect to identify the objects that could present strong variability. \


title:
Monoperiodic $\delta$ Scuti star UY Cam: an analogue of SX Phe and RR
  Lyr-type variables

abstract:
  We present the results of a four-year photometric study of the high-amplitude
$\delta$ Scuti star (HADS) UY Camelopardalis. Analyses on the available data
from 1985 to 2003 show that UY Cam is monoperiodic. Fourier solutions for
individual data sets do not reveal period changes in the star. Although forced
parabolic fits to the $O-C$ residuals indicate measurable period change, the
distribution of the data points in $O-C$ diagram and the deviations between
fits and observations suggest the period change is still not established. We
evidence the presence of cycle-to-cycle and longer time-scale amplitude
variations. The pulsation amplitude seemed to change from 1985 to 2000s, but it
kept constant in 2000--2003. UY Cam locates in the upper portion of the
instability region of $\delta$ Sct variables. Photometric properties and
estimated physical parameters reveal that UY Cam is an interesting object
concerning its poorer metallicity, longer period, higher luminosity, lower
surface gravity and larger radius among the HADS. UY Cam could be a younger
(age=0.7$\pm$0.1 Gyr) Population I HADS with poor metal abundances (Z=0.004)
evolving on its post main sequence shell hydrogen-burning evolutionary phase.
UY Cam intervenes among the Pop. I/II HADS and RRc Lyr variables. These
characteristics suggest the star to be an analogue of HADS, SX Phe and RRc
Lyr-type variables.


title: A Search for Planets in the Old Open Cluster NGC 6791

abstract:
  We describe the results of a search for transit-like events caused by giant
planets occulting stars in the old, metal-rich open cluster NGC 6791 based on
BVI-colour photometry from eight nights of observations with the 2.54m Nordic
Optical Telescope. To extract the light curves we have used both PSF photometry
(DAOPHOT) and the difference imaging technique (ISIS). We have re-analyzed
observations from earlier campaigns to search for multiple transits, determine
periods of long-period variables, and detect eclipsing binaries. We confirm 20
known variables and have discovered 22 new low-amplitude variables with
amplitudes in the range 7--40 mmag and periods 1--16 days. We have found the
primary and secondary eclipses of two eclipsing binaries based on the new and
older photometric campaigns. The search for transits-like events has turned up
a few single-transit candidates. The transit depths are 10 mmag in both the V
and I filters over periods of 1.0--2.5 hours, but future observations are
required to see whether identical transit-like events recur in these same
stars.


title:
Weak Lensing by High-Redshift Clusters of Galaxies II: Mean Redshift of
  the Faint Background Galaxy Population

abstract:
  We use weak lensing shear measurements of six z>0.5 clusters of galaxies to
derive the mean lensing redshift of the background galaxies used to measure the
shear. Five of these clusters are compared to X-ray mass models and verify a
mean lensing redshift for a 23<R<26.3, R-I<0.9 background galaxy population in
good agreement with photometric redshift surveys of the HDF-S. The lensing
strength of the six clusters is also analyzed as a function of the magnitude of
the background galaxies, and an increase in shear with increasing magnitude is
detected at moderate significance. The change in the strength of the shear is
presumed to be caused by an increase in the mean redshift of the background
galaxies with increasing magnitude, and the degree of change detected is also
in agreement with those in photometric redshift surveys of the HDF-S.


title:
Hydrodynamical simulations of the Sunyaev-Zel'dovich effect: cluster
  scaling relations and X-ray properties

abstract:
  The Sunyaev-Zel'dovich effect is a powerful new tool for finding and studying
clusters at high redshift, particularly in combination with their X-ray
properties. In this paper we quantify the expected scaling relations between
these properties using numerical simulations with various models for heating
and cooling of the cluster gas. For a Non-radiative model, we find scaling
relations in good agreement with self-similar predictions: $Y\propto T_X^{5/2}$
and $Y \propto L_X^{5/4}$. Our main results focus on predictions from Cooling
and Preheating simulations, shown by Muanwong et al. (2002) to provide a good
match to the X-ray scaling relations at z=0. For these runs we find slopes of
approximately $Y \proptoT_X^3$ and $Y \propto L_X$, steeper and flatter than
the self-similar scalings respectively. We also study the redshift evolution of
the scaling relations and find the slopes show no evidence of evolution out to
redshifts well beyond one, while the normalizations of relations between the SZ
signal and X-ray properties do show evolution relative to that expected from
self-similarity, particularly at z<1.


title:
The Planck High Frequency Instrument, a 3rd generation CMB experiment,
  and a full sky submillimeter survey

abstract:
  The High Frequency Instrument (HFI) of Planck is the most sensitive CMB
experiment ever planned. Statistical fluctuations (photon noise) of the CMB
itself will be the major limitation to the sensitivity of the CMB channels.
Higher frequency channels will measure galactic foregrounds. Together with the
Low Frequency Instrument, this will make a unique tool to measure the full sky
and to separate the various components of its spectrum. Measurement of the
polarization of these various components will give a new picture of the CMB. In
addition, HFI will provide the scientific community with new full sky maps of
intensity and polarization at six frequencies, with unprecedented angular
resolution and sensitivity. This paper describes the logics that prevailed to
define the HFI and the performances expected from this instrument. It details
several features of the HFI design that have not been published up to now.


title:
The hard X-ray view of the low-luminosity blazar in the radio galaxy
  NGC6251

abstract:
  We present results from a BeppoSAX (July 2001) observation of the FRI radio
galaxy NGC6251, together with a re-analysis of archival ASCA (October 1994) and
Chandra (September 2000) data. The weak detection above 10 keV and the lack of
iron fluorescent K-alpha emission lines in the BeppoSAX spectrum rule out that
the bulk of the X-ray emission is due to an obscured Seyfert nucleus. The study
of the multiwavelength spectral energy distribution suggests instead that
X-rays probably originate as inverse-Compton of synchrotron seed photons in a
relativistic jet, indicating that NGC6251 hosts a low radio luminosity [L(5
GHz) ~10^40 erg/s] blazar. The BeppoSAX spectrum is flatter than in the earlier
ASCA observation. This might be due to the emergence of a different spectral
component during phases of lower X-ray flux. In this context, we discuss some
possible explanations for the intense and mildly-ionized fluorescent iron line
measured by ASCA.


title:
Simulating the Early Evolution of the Hard X-Ray Properties of a Young
  Stellar Population

abstract:
  We present an X-ray binary population synthesis model, and use it to simulate
the evolution of X-ray binaries formed in a burst of star formation of duration
20 Myr and star-formation rate 10 M_sun/yr. Our goal is to explain the hard
(2-10 keV) X-ray properties of populations of extragalactic X-ray binaries
recently observed by the Chandra X-Ray Observatory, especially those associated
with recent or ongoing episodes of vigorous star formation. Our simulated X-ray
binary population reaches a maximum 2-10 keV luminosity of ~4e40 erg/s after
approximately 20 Myr. The X-ray luminous phase is sustained for a period of
several hundreds of Myr by succeeding populations of systems with lighter
secondary stars, i.e., it persists long after the star-formation episode has
ended. These results are insensitive to the poorly-constrained values of the
initial mass function and the average mass ratio between accreting and donor
stars. The computed peak X-ray luminosity is consistent with
observationally-derived correlations between the star-formation rate and the
observed hard X-ray luminosity. Model cumulative luminosity functions at the
earliest times have power-law indices in agreement with those derived from
observations of actively star-forming galaxies. The model cumulative luminosity
functions become increasingly steeper with time as the most luminous systems
die off, which offers an explanation for the difference in the slopes of
observed cumulative luminosity functions of young and old stellar populations.


title:
The effect of (strong) discrete absorption systems on the lyman alpha
  forest flux power spectrum

abstract:
  We demonstrate that the lyman alpha forest flux power spectrum of
``randomised'' QSO absorption spectra is comparable in shape and amplitude to
the flux power spectrum of the original observed spectra. In the randomised
spectra a random shift in wavelength has been added to the observed absorption
lines as identified and fitted with VPFIT. At 0.03 s/km <k<0.1 s/km the ``3D''
power spectrum of the randomised flux agrees with that of observed spectra
within the errors. At larger scales it is still greater than 50 % of that of
the observed spectra. At smaller scales the flux power spectrum is dominated by
metal lines. Lines of increasing column density contribute to the ``3D'' flux
power spectrum at increasingly larger scales. Lines with 13< log
(N_HI/cm^{-2})<15 dominate at the peak of the ``3D'' power spectrum while
strong absorbers with log (N_HI/cm^{-2})>15 dominate at large scales, k< 0.03
s/km. We further show that a fraction of up to 20 % of the mean flux decrement
is contributed by strong absorbers. Analysis of the flux power spectrum which
use numerical simulations with too few strong absorption systems calibrated
with the observed mean flux are likely to underestimate the inferred rms
fluctuation amplitude and the slope of the initial dark matter matter power
spectrum. In a combined analysis with other data which constrains the dark
matter power spectrum on larger scales this can result in a spurious detection
of a running spectral index.


title:
The 2 Ms Chandra Deep Field-North: Moderate-luminosity AGNs and dusty
  starburst galaxies

abstract:
  The 2 Ms Chandra Deep Field-North survey provides the deepest view of the
Universe in the 0.5--8.0 keV X-ray band. In this brief review we investigate
the diversity of X-ray selected sources and focus on the constraints placed on
AGNs (including binary AGNs) in high-redshift submm galaxies.


title: A Neighboring Dwarf Irregular Galaxy Hidden by the Milky Way

abstract:
  We have obtained VLA and optical follow-up observations of the low-velocity H
I source HIZSS 3 discovered by Henning et al. (2000) and Rivers (2000) in a
survey for nearby galaxies hidden by the disk of the Milky Way. Its radio
characteristics are consistent with this being a nearby (~1.8 Mpc) low-mass
dwarf irregular galaxy (dIm). Our optical imaging failed to reveal a resolved
stellar population, but did detect an extended H-alpha emission region. The
location of the H-alpha source is coincident with a partially-resolved H I
cloud in the 21-cm map. Spectroscopy confirms that the H$\alpha$ source has a
similar radial velocity to that of the H I emission at this location, and thus
we have identified an optical counterpart. The H$\alpha$ emission (100 pc in
diameter and with a luminosity of $1.4\times10^{38}$ ergs s$^{-1}$) is
characteristic of a single H II region containing a modest population of OB
stars. The galaxy's radial velocity and distance from the solar apex suggests
that it is not a Local Group member, although a more accurate distance is
needed to be certain. The properties of HIZSS 3 are comparable to those of GR
8, a nearby dIm with a modest amount of current star formation. Further
observations are needed to characterize its stellar population, determine the
chemical abundances, and obtain a more reliable distance estimate.


title: Chandra Observations of the Dwarf Nova WX Hyi in Quiescence

abstract:
  We report Chandra observations of the dwarf nova WX Hyi in quiescence. The
X-ray spectrum displays strong and narrow emission lines of N, O, Mg, Ne, Si, S
and Fe. The various ionization states implied by the lines suggest that the
emission is produced within a flow spanning a wide temperature range, from T ~
10^6 K to T >~ 10^8 K. Line diagnostics indicate that most of the radiation
originates from a very dense region, with n ~ 10^{13}-10^{14} cm^{-3}. The
Chandra data allow the first tests of specific models proposed in the
literature for the X-ray emission in quiescent dwarf novae. We have computed
the spectra for a set of models ranging from hot boundary layers, to hot
settling flows solutions, to X-ray emitting coronae. WX Hyi differs from other
dwarf novae observed at minimum in having much stronger low temperature lines,
which prove difficult to fit with existing models, and possibly a very strong,
broad O VII line, perhaps produced in a wind moving at a few x 10^3 km/s. The
accretion rate inferred from the X-rays is lower than the value inferred from
the UV. The presence of high-velocity mass ejection could account for this
discrepancy while at the same time explaining the presence of the broad O VII
line. If this interpretation is correct, it would provide the first detection
of a wind from a dwarf nova in quiescence.


title: Gravitational Radiation from Pulsating White Dwarfs

abstract:
  Rotating white dwarfs undergoing quasi-radial oscillations can emit
gravitational radiation in a frequency range from 0.1 - 0.3 Hz. Assuming that
the energy source for the gravitational radiation comes from the oblateness of
the white dwarf induced by the rotation, the strain amplitude is found to be
\sim 10^{-27} for a white dwarf at \sim 50 pc. The galactic population of these
sources is estimated to be \sim 10^7, and may produce a confusion limited
foreground for proposed advanced detectors in the frequency band between
space-based and ground-based interferometers. Nearby oscillating white dwarfs
may provide a clear enough signal to investigate white dwarf interiors through
gravitational wave asteroseismology.


title:
Asymmetric Deviation of the Scattering Cross Section around Ly$\alpha$
  by Atomic Hydrogen

abstract:
  We investigate the asymmetry of the scattering cross section of radiation
around Ly$\alpha$ by atomic hydrogen, which may be applied to analyses of
scattering media with high column neutral hydrogen densities including damped
Ly$\alpha$ absorption systems of quasars. The exact scattering cross section is
given by the Kramers-Heisenberg formula obtained from the fully quantum
mechanical second-order time dependent theory, where, in the case of hydrogen,
each matrix element is given in a closed analytical form. The asymmetric
deviation of the scattering cross section from the Lorentzian near the line
center is computed by expanding the Kramers-Heisenberg formula in terms of
$\Delta\omega /\omega_{Ly\alpha}$,where $\omega_{Ly\alpha}$ is the angular
frequency of the Ly$\alpha$ transition and $\Delta\omega$ is the deviation of
incident radiation from $\omega_{Ly\alpha}$. To the first order of
$\Delta\omega/\omega_{Ly\alpha}$, we obtain $\sigma(\omega) = \sigma_T (0.5
f_{12} \omega_{Ly\alpha}/\Delta\omega)^2 (1-1.79\Delta\omega /
\omega_{Ly\alpha})$, where $\sigma_T$ is the Thomson scattering cross section
and $f_{12}=0.4162$ is the oscillator strength for the Ly$\alpha$ transition.
With this deviation, the line center of the damped wing profile apparently
shifts blueward of the true Ly$\alpha$ line center. In the case of a
dampedLy$\alpha$ system with a H I column density $5\times 10^{21}{\rm
cm^{-2}}$, the apparent line center shift relative to the true center amounts
to $0.2{\rm \AA}$ resulting in an underestimation of redshift by $\Delta z\sim
10^{-4}$. A measurable underestimation by an amount of $\Delta z\sim 10^{-3}$
is expected for absorbing systems with $N_{HI}\ge 4\times 10^{22}{\rm
cm^{-2}}$.


title:
Raman Scattered He II $\lambda$ 6545 Line in the Symbiotic Star V1016
  Cygni

abstract:
  We present a spectrum of the symbiotic star V1016 Cyg observed with the 3.6 m
Canada-France-Hawaii Telescope, in order to illustrate a method to measure the
covering factor of the neutral scattering region around the giant component
with respect to the hot emission region around the white dwarf component. In
the spectrum, we find broad wings around H$\alpha$ and a broad emission feature
around 6545${\rm \AA}$ that is blended with the [N II]$ \lambda$ 6548 line.
These two features are proposed to be formed by Raman scattering by atomic
hydrogen, where the incident radiation is proposed to be UV continuum radiation
around Ly$\beta$ in the former case and He II $\lambda$ 1025 emission line
arising from $n=6\to n=2$ transitions for the latter feature. We remove the
H$\alpha$ wings by a template Raman scattering wing profile and subtract the [N
II] $\lambda$ 6548 line using the 3 times stronger [N II] $\lambda$ 6583
feature in order to isolate the He II Raman scattered 6545 \AA line. We obtain
the flux ratio $F_{6545}/F_{6560}=0.24$ of the He II $\lambda$ 6560 emission
line and the 6545 \AA feature for V1016 Cyg. Under the assumption that the He
II emission from this object is isotropic, this ratio is converted to the ratio
$\Phi_{6545}/\Phi_{1025}=0.17$ of the number of the incident photons and that
of the scattered photons. This implies that the scattering region with H I
column density $N_{HI}\ge 10^{20}{\rm cm^{-2}}$ covers 17 per cent of the
emission region. By combining the presumed binary period $\sim 100$ yrs of this
system we infer that a significant fraction of the slow stellar wind from the
Mira component is ionized and that the scattering region around the Mira
extends a few tens of AU, which is closely associated with the mass loss
process of the Mira component.


title:
H-Alpha and Hard X-Ray Observations of a Two-Ribbon Flare Associated
  with a Filament Eruption

abstract:
  We perform a multi-wavelength study of a two-ribbon flare on 2002 September
29 and its associated filament eruption, observed simultaneously in the H-alpha
line by a ground-based imaging spectrograph and in hard X-rays by RHESSI. The
flare ribbons contain several H-alpha bright kernels that show different
evolutional behaviors. In particular, we find two kernels that may be the
footpoints of a loop. A single hard X-ray source appears to cover these two
kernels and to move across the magnetic neutral line. We explain this as a
result of the merging of two footpoint sources that show gradually asymmetric
emission owing to an asymmetric magnetic topology of the newly reconnected
loops. In one of the H-alpha kernels, we detect a continuum enhancement at the
visible wavelength. By checking its spatial and temporal relationship with the
hard X-ray emission, we ascribe it as being caused by electron beam
precipitation. In addition, we derive the line-of-sight velocity of the
filament plasma based on the Doppler shift of the filament-caused absorption in
the H-alpha blue wing. The filament shows rapid acceleration during the
impulsive phase. These observational features are in principal consistent with
the general scenario of the canonical two-ribbon flare model.


title:
Detection of Short Fading Episodes in Two Dwarf Novae from VSNET
  Observations

abstract:
  From the observations reported to VSNET, we detected short fading episodes in
two dwarf novae, RX And (orbital period 5.0 hr) and SU UMa (orbital period 1.8
hr). The episodes in RX And can be naturally explained as the response to a
short-term reduction of the mass-transfer rate. A qualitative comparison with
VY Scl-type fadings is also discussed. In SU UMa, the same explanation is
expected to be more difficult to apply. The viable, but still poorly
understood, possibilities include the temporary reduction of quiescent disk
viscosity and the temporary reduction of mass-transfer rate. If the latter
possibility is confirmed, we probably need a different mechanism from that of
VY Scl-type stars.


title:
Kinematical structure of the circumstellar environments of galactic
  B[e]-type stars

abstract:
  High resolution line profiles are presented for selected forbidden and
permitted emission lines of a sample of galactic B[e]-type stars. The spectral
resolution corresponds to 5-7 km/s with the exception of some line profiles
which were observed with a resolution of 9-13 km/s. All Ha profiles are
characterized by a narrow split or single emission component with a width of
about 150-250 km/s (FWHM) and broad wings with a full width of ~1000-2000 km/s.
The Ha profiles can be classified into three groups: double-peaked profiles
representing the majority, single-peaked emission-line profiles, and normal P
Cygni-type profiles. The forbidden lines exhibit in most cases double-peaked
profiles. The split forbidden line profiles have peak separations of as little
as 10 km/s. The ratio of violet to red emission peak intensities, V/R, is
predominantly smaller or equal to 1. Theoretical profiles were calculated for
the optically thin case. A latitude-dependent stellar wind with a radial
expansion and a velocity decreasing from the pole to the equator was adopted.
In addition an equatorial dust ring with various optical depths was assumed.
This model can explain split lines and line asymmetries observed in some stars.
Moreover, the V/R ratios can be understood in terms of this model. The
comparison of the observed line profiles with the models thus confirms the
assumption of disk-like line-formation regions as commonly adopted for
B[e]-type stars.


title: Enhancement of Non-Gaussianity after Inflation

abstract:
  We study the evolution of cosmological perturbations on large scales, up to
second order, for a perfect fluid with generic equation of state. Taking
advantage of super-horizon conservation laws, it is possible to follow the
evolution of the non-Gaussianity of perturbations through the different stages
after inflation. We find that a large non-linearity is generated by the
gravitational dynamics from the original inflationary quantum fluctuations.
This leads to a significant enhancement of the tiny intrinsic non-Gaussianity
produced during inflation in single-field slow-roll models.


title: Delays in dwarf novae I: The case of SS Cygni

abstract:
  Using the disc instability model and a simple but physically reasonable model
for the X-ray, extreme UV, UV and optical emission of dwarf novae we
investigate the time lags observed between the rise to outburst at different
wavelengths. We find that for ``normal'', i.e. fast-rise outbursts, there is
good agreement between the model and observations provided that the disc is
truncated at a few white dwarf radii in quiescence, and that the viscosity
parameter alpha is ~0.02 in quiescence and ~0.1 in outburst. In particular, the
increased X-ray flux between the optical and EUV rise and at the end of an
outburst, is a natural outcome of the model. We cannot explain, however, the
EUV delay observed in anomalous outbursts because the disc instability model in
its standard alpha-prescription form is unable to produce such outbursts. We
also find that the UV delay is, contrary to common belief, slightly longer for
inside-out than for outside-in outbursts, and that it is not a good indicator
of the outburst type.


title: The Galactic dust as a foreground to Cosmic Microwave Background maps

abstract:
  We present results obtained with the PRONAOS balloon-borne experiment on
interstellar dust. In particular, the submillimeter / millimeter spectral index
is found to vary between roughly 1 and 2.5 on small scales (3.5' resolution).
This could have implications for component separation in Cosmic Microwave
Background maps.


title:
A Chandra Observation of the Diffuse Emission in the Face-on Spiral NGC
  6946

abstract:
  This paper describes the {\it Chandra} observation of the diffuse emission in
the face-on spiral NGC 6946. Overlaid on optical and H${\alpha}$ images, the
diffuse emission follows the spiral structure of the galaxy. An overlay on a 6
cm polarized radio intensity map confirms the phase offset of the polarized
emission. We then extract and fit the spectrum of the unresolved emission with
several spectral models. All model fits show a consistent continuum thermal
temperature with a mean value of 0.25$\pm$0.03 keV. Additional degrees of
freedom are required to obtain a good fit and any of several models satisfy
that need; one model uses a second continuum component with a temperature of
0.70$\pm$0.10 keV. An abundance measure of 3$^{+1.95}_{-1.90}$ for Si differs
from the solar value at the 90% confidence level; the net diffuse spectrum
shows the line lies above the instrumental Si feature. For Fe, the abundance
measure of 0.67$\pm$0.13 is significant at 99%. Multiple gaussians also provide
a good fit. Two of the fitted gaussians capture the O VII and O VIII emission;
the fitted emission is consistent with an {\it XMM-Newton} RGS spectrum of
diffuse gas in M81. The ratio of the two lines is $<$0.6-0.7 and suggests the
possibility of non-equilibrium ionization conditions exist in the ISM of NGC
6946. An extrapolation of the point source luminosity distribution shows the
diffuse component is not the sum of unresolved point sources; their
contribution is at most 25%.


title: Supersymmetric Dark Matter with GLAST

abstract:
  We present a short review of the status of the dark matter problem. In
particular we show that one of the best motivated candidate for the dark matter
is the neutralino, a supersymmetric particle. Finally we study the possibility
to detect gamma rays coming from neutralino pair annihilations that take place
in our Galactic Center with the upcoming satellite detector GLAST.


title: Mass and dust in the disk of a spiral lens galaxy

abstract:
  Gravitational lensing is a potentially important probe of spiral galaxy
structure, but only a few cases of lensing by spiral galaxies are known. We
present Hubble Space Telescope and Magellan observations of the two-image
quasar PMN J2004-1349, revealing that the lens galaxy is a spiral galaxy. One
of the quasar images passes through a spiral arm of the galaxy and suffers 3
magnitudes of V-band extinction. Using simple lens models, we show that the
mass quadrupole is well-aligned with the observed galaxy disk. A more detailed
model with components representing the bulge and disk gives a bulge-to-disk
mass ratio of 0.16 +/- 0.05. The addition of a spherical dark halo, tailored to
produce an overall flat rotation curve, does not change this conclusion.


title: HD 34700: A new T Tauri double-lined spectroscopic binary

abstract:
  We find the star HD 34700 to be a double-lined spectroscopic binary. We also
identify it as a weak-line T Tauri object The spectra of both components are
very similar and both show the Li I feature at 6708 \AA. Strong arguments in
favour of the binary nature of the star as opposed to other possibilities are
offered. It is very likely that the companion is also a T Tauri star of similar
mass. A projected rotational velocity, $v$sin$i$, of 25 and 23 km/s$^{-1}$ has
been estimated for the blue and red components. We present a list of the lines
identified and the radial velocities of the two components on three spectra
obtained on consecutive nights.


title: The Effect of Scattering on Pulsar Polarization Angle

abstract:
  The low-frequency profiles of some pulsars manifest temporal broadening due
to scattering, usually accompanied by flat polarization position angle (PA)
curves. Assuming that the scattering works on the 4 Stokes parameters in the
same way, we have simulated the effect of scattering on polarization profiles
and find that the scattering can indeed flatten the PA curves. Since the
higher-frequency profiles suffer less from scattering, they are convolved with
scattering models to fit the observed low-frequency profiles. The calculated
flat PA curves exactly reproduce the corresponding observations.


title: On the origin of the various types of radio emission in GRS 1915+105

abstract:
  We investigate the association between the radio ``plateau'' states and the
large superluminal flares in GRS 1915+105 and propose a qualitative scenario to
explain this association. We identify several candidate superluminal flare
events from available monitoring data on this source and analyze the
contemporaneous RXTE pointed observations. We detect a strong correlation
between the average X-ray flux during the ``plateau'' state and the total
energy emitted in radio during the subsequent radio flare. We find that the
sequence of events is similar for all large radio flares with a fast rise and
exponential decay morphology. Based on these results, we propose a qualitative
scenario in which the separating ejecta during the superluminal flares are
observed due to the interaction of the matter blob ejected during the X-ray
soft dips, with the steady jet already established during the ``plateau''
state. This picture can explain all types of radio emission observed from this
source in terms of its X-ray emission characteristics.


title: The far-IR/radio correlation in the ISO era

abstract:
  We present the correlation between the far-infrared (FIR) and radio emissions
from a composite sample of 72 nearby normal galaxies observed with the ISOPHOT
instrument on board the Infrared Space Observatory. The galaxies in the sample
have measurements at three FIR wavelengths (60, 100 and 170 micron), which
allowed a direct determination of the warm and cold FIR emission components.
This is the first time that the correlation has been established for the total
FIR luminosity, of which most is carried by the cold dust component
predominantly emitting longwards of the spectral coverage of IRAS. The slope of
this correlation is slightly non-linear (1.10+/-0.03). Separate correlations
between the warm and cold FIR emission components and the radio emission have
also been derived. The slope of the warm FIR/radio correlation was found to be
linear (1.03+/-0.03). For the cold FIR/radio correlation we found a slightly
non-linear (1.13+/-0.04) slope. We qualitatively interpret the correlations in
terms of star formation rate and find that both the FIR and radio emissions may
be consistent with a non-linear dependence on star formation rate for galaxies
not undergoing starburst activity.


title: Chemistry and clumpiness in planetary nebulae

abstract:
  We study the chemistry in the slow wind during the transition from AGB star
to pre-planetary nebula (PPN) and planetary nebula (PN). We show that there is
a very rich chemistry of degradation products created by photoprocessing,
driven by the gradually hardening radiation field of the central star. Most of
these products are, however, photodissociated during the PPN phase if the wind
is smooth. By contrast, if the wind is clumpy, possibly because of clumpiness
in the AGB atmosphere, then many of these degradation products survive into the
PN phase. Thus, chemistry may be used to infer the existence of clumpiness in
the AGB phase. We identify potential molecular tracers, and we note that, in
the case of clumpiness, large molecules may survive the transport from the
stellar atmosphere to the interstellar medium. We compare between our model
results with observations of three objects at differing evolutionary stages:
CRL618, NGC 7027 and the Helix nebula (NGC 7293).


title: Non-Gaussian Error Distribution of Hubble Constant Measurements

abstract:
  We construct the error distribution of Hubble constant ($H_0$) measurements
from Huchra's compilation of 461 measurements of $H_0$ and the WMAP experiment
central value $H_0$ = 71 km s$^{-1}$ Mpc$^{-1}$. This error distribution is
non-Gaussian, with significantly larger probability in the tails of the
distribution than predicted by a Gaussian distribution. The 95.4 % confidence
limits are 7.0 $\sigma$ in terms of the quoted errors. It is remarkably well
described by either a widened $n = 2$ Student's $t$ distribution or a widened
double exponential distribution. These conclusions are unchanged if we use
instead the central value $H_0$ = 67 km s$^{-1}$ Mpc$^{-1}$ found from a median
statistics analysis of a major subset of $H_0$ measurements used here.


title: A Search for TeV Gamma-Ray Burst Emission with the Milagro Observatory

abstract:
  The Milagro telescope monitors the northern sky for 100 GeV - 100 TeV
transient emission through continuous very high energy wide-field observations.
The large effective area and low energy threshold of Milagro allow it to detect
very high energy gamma-ray burst emission with much higher sensitivity than
previous instruments, and a fluence sensitivity at TeV energies comparable to
dedicated gamma-ray burst satellites at keV-MeV energies. Observation of
gamma-ray burst emission at TeV energies could place important constraints on
gamma-ray burst progenitor and emission models. This study details the
development of a weighted analysis technique; the implementation of this
technique to perform a real time search for TeV transients of 40 seconds to 3
hours duration in the Milagro data; and the results from more than one year of
observation. Between May 2nd, 2001, and May 22nd, 2002, no TeV transients of 40
seconds to 3 hours duration were observed. Upper limits on both observed and
emitted high energy gamma-ray burst emission are presented.


title:
Circumnuclear Shock and Starburst in NGC 6240: Near-IR Imaging and
  Spectroscopy with Adaptive Optics

abstract:
  We have obtained adaptive optics, high spatial resolution (0.15 arcsecond)
K-band spectra and images of the region around the two active nuclei in NGC
6240 which show the presence of circumnuclear shocks. The data are consistent
with the thermal excitation mechanism being the dominant one in the nuclear
region. UV fluorescence and associative detachment may also contribute to the
fraction of the energy emitted through molecular hydrogen transitions. The
near-IR continuum emission appears closely associated with the two active
nuclei. The morphological similarities between the near-IR images and the
Chandra X-ray images indicate the same mechanisms may be responsible for the
emission in near-IR and X-ray band.


title: Diffuse X-ray emission in spiral galaxies

abstract:
  We compare the soft diffuse X-ray emission from Chandra images of 12 nearby
intermediate inclination spiral galaxies to the morphology seen in Halpha,
molecular gas, and mid-infrared emission. We find that diffuse X-ray emission
is often located along spiral arms in the outer parts of spiral galaxies but
tends to be distributed in a rounder morphology in the center. The X-ray
morphology in the spiral arms matches that seen in the mid-infrared or Halpha
and so implies that the X-ray emission is associated with recent active star
formation. We see no strong evidence for X-ray emission trailing the location
of high mass star formation in spiral arms. However, population synthesis
models predict a high mechanical energy output rate from supernovae for a time
period that is about 10 times longer than the lifetime of massive ionizing
stars, conflicting with the narrow appearance of the arms in X-rays. The
fraction of supernova energy that goes into heating the ISM must depend on
environment and is probably higher near sites of active star formation. The
X-ray estimated emission measures suggest that the volume filling factors and
scale heights are high in the galaxy centers but low in the outer parts of
these galaxies. The differences between the X-ray properties and morphology in
the centers and outer parts of these galaxies suggest that galactic fountains
operate in outer galaxy disks but that winds are primarily driven from galaxy
centers.


title:
The power spectrum of the flux distribution in the Lyman-alpha forest of
  a Large sample of UVES QSO Absorption Spectra (LUQAS)

abstract:
  The flux power spectra of the Lyman-alpha forest from a sample of 27 QSOs
taken with the high resolution echelle spectrograph UVES on VLT are presented.
We find a similar fluctuation amplitude at the peak of the ``3D'' flux power
spectrum at k ~ 0.03 (km/sec)^(-1) as the study by Croft et al. (2002), in the
same redshift range. The amplitude of the flux power spectrum increases with
decreasing redshift if corrected for the increase in the mean flux level as
expected if the evolution of the flux power spectrum is sensitive to the
gravitational growth of matter density fluctuations. This is in agreement with
the findings of McDonald et al. (2000) at larger redshift. The logarithmic
slope of the "3D" flux power spectrum, P_F(k), at large scales k < 0.03
(km/sec)^(-1), is 1.4 +- 0.3, i.e. 0.3 shallower than that found by Croft et
al. (2002) but consistent within the errors.


title:
Magnetic Field Generation in Collisionless Shocks; Pattern Growth and
  Transport

abstract:
  We present results from three-dimensional particle simulations of
collisionless shocks with relativistic counter-streaming ion-electron plasmas.
Particles are followed over many skin depths downstream of the shock. Open
boundaries allow the experiments to be continued for several particle crossing
times. The experiments confirm the generation of strong magnetic and electric
fields by a Weibel-like kinetic streaming instability, and demonstrate that the
electromagnetic fields propagate far downstream of the shock. The magnetic
fields are predominantly transversal, and are associated with merging ion
current channels. The total magnetic energy grows as the ion channels merge,
and as the magnetic field patterns propagate down stream. The electron
populations are quickly thermalized, while the ion populations retain distinct
bulk speeds in shielded ion channels and thermalize much more slowly. These
results may help explain the origin of the magnetic fields responsible for
afterglow synchrotron/jitter radiation from Gamma-Ray Bursts.


title: Hydrogen Clouds before Reionization: a Lognormal Model Approach

abstract:
  We study the baryonic gas clouds (the IGM) in the universe before the
reionization with the lognormal model which is shown to be dynamcially
legitimate in describing the fluctuation evolution in quasilinear as well as
nonlinear regimes in recent years. The probability distribution function of the
mass field in the LN model is long tailed and so plays an important role in
rare events, such as the formation of the first generation of baryonic objects.
We calculate density and velocity distributions of the IGM at very high spatial
resolutions, and simulate the distributions at resolution of 0.15 kpc from z=7
to 15 in the LCDM cosmological model. We performed a statistics of the hydrogen
clouds including column densities, clumping factors, sizes, masses, and spatial
number density etc. One of our goals is to identify which hydrogen clouds are
going to collapse. By inspecting the mass density profile and the velocity
profile of clouds, we found that the velocity outflow significantly postpones
the collapsing process in less massive clouds, in spite of their masses are
larger than the Jeans mass. Consequently, only massive (> 10^5 M_sun) clouds
can form objects at higher redshift, and less massive (10^4-10^5) collapsed
objects are formed later. For example, although the mass fraction in clouds
with sizes larger than the Jeans length is already larger than 1 at z=15, there
is only a tiny fraction of mass (10^{-8}) in the clouds which are collapsed at
that time. If all the ionizing photons, and the 10^{-2} metallicity observed at
low redshift are produced by the first 1% mass of collapsed baryonic clouds,
the majority of those first generation objects would not happen until z=10.


title:
XMM-Newton observation of the X-ray point source population of the
  starburst galaxy IC342

abstract:
  We present the results of an XMM-Newton observation of the starburst galaxy
IC342. Thirty-seven X-ray point sources were detected down to a luminosity
limit of $\sim 10^{37}$ \lum. Most of the sources are located near the spiral
arms. The X-ray point source luminosity function is consistent with a power-law
shape with a slope of 0.55, typical of starburst galaxies. We also present the
energy spectra of several ultraluminous X-ray sources (ULXs), including the
luminous X-ray source in the galactic nucleus. Except for the nucleus and a
luminous supersoft X-ray source, other ULXs can generally be fit with a simple
power-law spectral model. The nucleus is very luminous ($\sim 10^{40}$\lum in
0.2-12 keV) and requires disc blackbody and power-law components to describe
the X-ray emission. The spectral fit reveals a cool accretion disc (kT=0.11
keV) and suggests that the source harbours either an intermediate-mass black
hole or a stellar-mass black hole with outflow.


title: Oscillating cosmological solutions within gauge theories of gravity

abstract:
  New type of nonsingular oscillating solutions for the Universe described by
cosmological equations of gauge theories of gravity is presented. Advantages of
these solutions with respect to existing nonsingular solutions within framework
of general relativity and gauge gravity are discussed. It is shown in
particular that these solutions have nonzero measure and stable on contraction
stage unlike usual nonsingular solutions.


title: Measuring the Interplanetary Medium with a Solar Sail

abstract:
  NASA has been considering a solar sail that would accelerate a craft to a
high velocity (~ 14 AU/yr) by the time it reached 5 AU. Then the sail would be
dropped and the craft would coast alone to deep space. We propose that the sail
be retained longer. Then the density of the interplanetary medium could be
determined by measuring the drag force on the huge sail using radiometric
navigational data. Such an experiment would yield an independent, new type of
measurement of the interplanetary medium and should be pursued.


title:
Diffuse Non-thermal X-ray Emission: Evidence for Cosmic-ray Acceleration
  at the Shock Front in IC1262

abstract:
  We report the first localization of diffuse, non-thermal, X-ray emission from
a nearby galaxy cluster. Using Chandra data, we have isolated a diffuse
non-thermal X-ray component with a photon index, Gamma_ X = 2.21 +0.14 -0.15
and a flux of 9.5 +1.1 -2.5 x 10^-5 photons cm^-2 s^-1 keV^-1 at 1 keV, that
extends from ~1'.5 to ~2'.5 to the south of the X-ray flux peak. Comparison to
simulations implies that the diffuse non-thermal emission is produced by
primary electrons, accelerated at shocks to relativistic velocities. Using
these results and the flux and hardness maps produced with data from the
Chandra Advanced CCD Imaging Spectrometer, we conclude that a smaller subclump
coming from the north merged with IC1262. The offset of the cD galaxy from the
X-ray peak and large peculiar velocity indicate that the subclump's impact
parameter was to the west and on the near side of IC1262.


title:
Interrelating Binarity, Physical Properties and Orbital Evolution of
  Near Earth Asteroids: A New Numerical Approach

abstract:
  Possible connections between the physical properties of Near-Earth Asteroids
(NEA) and their orbital evolution were explored, with emphasis on binary
asteroids. Our main starting hypothesis, suggested from the observations, was
that the NEA population contains considerably higher percent of binaries
compared to the Main Belt. The simulation covered simultaneously both orbital
evolution and evolution of physical properties, which is the main improvement
in comparison to the previous researches of this kind. Physical evolution due
to tidal forces and collision/disruption events was described with TREESPH
hydrocode. The results show typical evolution paths of some types of NEA:
asteroids with a satellite, synchronized binaries, single fast rotators, double
asteroids. The two latter types and their physical properties match closely to
some observed NEA, while the two former ones have not been detected in
observational practice. We conjecture that this is partly due to selection
effects of current observational techniques but partly also because some of
them are likely to evolve into different types of objects (e. g. single slow
rotators) through the processes we have not taken into account in our
simulation. The total percentage of binaries among NEA can be estimated to 12%.
We have to notice, however, that more detailed simulations, performed for
longer time spans, are needed to confirm our results.


title: Palatini form of 1/R gravity

abstract:
  It has been suggested that the recent acceleration of the expansion of the
Universe is due a modified gravitational action consisting of the
Einstein-Hilbert term plus a term proportional to the reciprocal of the Ricci
scalar. Although the original version of this theory has been shown to be in
conflict with solar system observations, a modified Palatini version of the
theory, in which the metric and connection are treated as independent variables
in the variational principle, has been suggested as a viable model of the
cosmic acceleration. We show that this theory is equivalent to a type of
scalar-tensor theory in which the scalar field kinetic energy term in absent
from the action, and in which the scalar field is therefore not an independent
dynamical degree of freedom. Integrating out the scalar field gives rise to
additional interactions among the matter fields of the standard model of
particle physics at a energy scale of order 10^(-3) eV (the geometric mean of
the Hubble scale and the Planck scale), and so the theory is excluded by, for
example, electron-electron scattering experiments.


title: Resonant inclination excitation of migrating giant planets

abstract:
  The observed orbits of extrasolar planets suggest that many giant planets
migrate a considerable distance towards their parent star as a result of
interactions with the protoplanetary disk, and that some of these planets
become trapped in eccentricity-exciting mean motion resonances with one another
during this migration. Using three-dimensional numerical simulations, we find
that as long as the timescale for damping of the planets' eccentricities by the
disk is close to or longer than the disk-induced migration timescale, and the
outer planet is more than half the mass of the inner, resonant inclination
excitation will also occur. Neither the addition of a (simple, fixed) disk
potential, nor the introduction of a massive inner planetary system, inhibit
entry into the inclination resonance. Therefore, such a mechanism may not be
uncommon in the early evolution of a planetary system, and a significant
fraction of exoplanetary systems may turn out to be non-coplanar.


title:
Multi-band optical follow-up observations of GRB 020813 at KISO and
  Bisei observatories

abstract:
  Observations were made of the optical afterglow of GRB020813 (Fox, Blake &
Price, 2002) with the KISO observatory 1.05 m Schmidt telescope and the Bisei
astronomical observatory 1.01 m telescope. Four-band ($B, V, R$, and $I$)
photometric data points were obtained from 2002, August 13 10:52 to 16:46 UT,
or 0.346$-$0.516 days after the burst. In order to investigate the early-time
($<$1 day) evolution of the afterglow, four-band light curves were produced by
analyzing the data taken at these two astronomical observatories, as well as
publicly released data taken by the Magellan Baade telescope (Gladders and
Hall, 2002c). The light curves can be approximated by a broken power law, of
which the indices are approximately 0.46 and 1.33 before and after a break at
$\sim$0.2 days, respectively. The optical spectral index stayed approximately
constant at $\sim$0.9 over 0.17 $\sim$ 4.07 days after the burst. Since the
temporal decay index after the break and the spectral index measured at that
time are both consistent with those predicted by a spherical expansion model,
the early break is unlikely to be a jet break, but likely to represent the end
of an early bump in the light curve as was observed in the optical afterglow of
GRB021004.


title:
The Force of Gravity from a Lagrangian containing Inverse Powers of the
  Ricci Scalar

abstract:
  We determine the gravitational response to a diffuse source, in a locally de
Sitter background, of a class of theories which modify the Einstein-Hilbert
action by adding a term proportional to an inverse power of the Ricci scalar.
We find a linearly growing force which is not phenomenologically acceptable.