title: The Formation of a Disk Galaxy within a Growing Dark Halo

abstract:
  We present a dynamical model for the formation and evolution of a massive
disk galaxy, within a growing dark halo whose mass evolves according to
cosmological simulations of structure formation. The galactic evolution is
simulated with a new 3D chemo-dynamical code, including dark matter, stars and
a multi-phase ISM. The simulations start at redshift z=4.85 with a small dark
halo in a LCDM universe and we follow the evolution until the present epoch.
The energy release by massive stars and SNe prevents a rapid collapse of the
baryonic matter and delays the maximum star formation until z=1. The galaxy
forms radially from inside-out and vertically from halo to disk. The first
galactic component that forms is the halo, followed by the bulge, the disk-halo
transition region, and the disk. At z=1, a bar begins to form which later turns
into a triaxial bulge. There is a pronounced deficiency of low-metallicity disk
stars due to pre-enrichment of the disk ISM with metal-rich gas from the bulge
and inner disk (G-dwarf problem). The mean rotation and the distribution of
orbital eccentricities for all stars as a function of metallicity are not very
different from those observed in the solar neighbourhood, showing that
homogeneous collapse models are oversimplified. The approach presented here
provides a detailed description of the formation and evolution of an isolated
disk galaxy in a LCDM universe, yielding new information about the kinematical
and chemical history of the stars and the ISM, but also about the evolution of
the luminosity, the colours and the morphology of disk galaxies.


title:
The structure of H2O shells in Mira atmospheres: Correlation with disk
  brightness distributions and a spectrophotometric signature

abstract:
  Dynamic models of M-type Mira variables predict the occurrence of water
"shells", i.e. of zones of high H2O density and high H2O absorption inside the
stellar atmosphere. The density, position and width of these shells is closely
correlated with different types of two-component shapes of the intensity
distribution on the disk in the H, K and L near-continuum bandpasses. We
investigate these correlations and highlight the role of a spectrophotometric
H2O index that warns against serious complications in diameter measurements in
the case of substantial water contamination of the bandpass of observation.
Simultaneous spectrophotometric and interferometric measurements may allow
observers to estimate real continuum diameters more precisely.


title:
Hydrodynamic time correlation functions in the presence of a
  gravitational field

abstract:
  This paper shows that the ordinary Brillouin spectrum peaks associated to
scattered radiation off acoustic modes in a fluid suffer a shift in their
values due to gravitational effects. The approach is based in the ordinary
linearized Navier-Stokes equations for a fluid coupled to a Newtonian
gravitational potential. The formalism leads to a dispersion relation that
contains both gravitational and dissipative effects. It is also shown that the
Brillouin peaks tend to condense into a single peak when the fluid modes
approach the critical Jeans wave number.


title: Variability of the Accretion Stream in the Eclipsing Polar EP Dra

abstract:
  We present the first high time resolution light curves for six eclipses of
the magnetic cataclysmic variable EP Dra, taken using the superconducting
tunnel junction imager S-Cam2. The system shows a varying eclipse profile
between consecutive eclipses over the two nights of observation. We attribute
the variable stream eclipse after accretion region ingress to a variation in
the amount and location of bright material in the accretion stream. This
material creates an accretion curtain as it is threaded by many field lines
along the accretion stream trajectory. We identify this as the cause of
absorption evident in the light curves when the system is in a high accretion
state. We do not see direct evidence in the light curves for an accretion spot
on the white dwarf; however, the variation of the stream brightness with the
brightness of the rapid decline in flux at eclipse ingress indicates the
presence of some form of accretion region. This accretion region is most likely
located at high colatitude on the white dwarf surface, forming an arc shape at
the foot points of the many field lines channeling the accretion curtain.


title:
Molar mass estimate of dark matter from the dark mass distribution
  measurements

abstract:
  We study the distribution of dark matter versus visible matter using a set of
data obtained from strong gravitational lensing in the galaxy cluster
CL0024+1654 and another set of data inferred from the universal rotation curves
in spiral galaxies. The important feature of these two dramatically different
observations is that the mass density profile of both visible and dark
components can be estimated. From these measurements we deduce the mass of the
dark matter particle and our estimate of the mass for the dark matter particle
is $\mu_d \approx (200-800)$MeV. We contrast our estimates from CL0024+1654
data and the universal rotation curves of the spiral galaxies and discuss their
consistency.


title: Nonlinearity of nonradial modes in evolved stars

abstract:
  We show that in evolved stars, even at relatively low surface amplitudes,
nonradial modes become strongly nonlinear in the hydrogen shell source, where
the Brunt-Vaisala frequency has its absolute maximum. The measure of
nonlinearity is the product of horizontal displacement times the radial
wavenumber. It becomes large already in evolved delta-Scuti stars. This
nonlinearity presents a major problem for interpretations of amplitude
modulation in RR Lyrae stars in terms of nonradial mode excitation.


title: TASI Lectures on Dark Matter

abstract:
  Observational evidence and theoretical motivation for dark matter are
presented and connections to the CMB and BBN are made. Problems for baryonic
and neutrino dark matter are summarized. Emphasis is placed on the prospects
for supersymmetric dark matter.


title: The PWN torus of PSR J0538+2817 and the Origin of Pulsar Velocities

abstract:
  We find evidence for a faint wind nebula surrounding PSR J0538+2817 in
CXO-ACIS imaging. This object is particularly interesting, as the pulsar
spindown age is largest for any such X-ray PWN. If interpreted as an equatorial
torus, the PWN supports the claimed association with the S147 supernova remnant
and implies good alignment between the pulsar spin and space velocity.
Comparison of the SNR age, X-ray cooling age and characteristic age suggests a
birth spin period of >130ms. In turn, if we accept as causal the alignment of
the linear and angular momenta, this places strong constraints on the origin of
the `kick' at the neutron star birth.


title: Does the fine-structure constant vary with cosmological epoch?

abstract:
  We use the strong nebular lines of O III, 5007 A and 4959 A, to set a robust
upper limit on the time dependence of the fine structure constant. We find
|alpha^{-1} d alpha(t)/dt | < 2*10^{-13} yr, corresponding to Delta
alpha/alpha(0) = (0.7 +- 1.4) * 10^{-4} for quasars with 0.16 < z < 0.80
obtained from the SDSS Early Data Release. Using a blind analysis, we show that
the upper limit given here is invariant with respect to 17 different ways of
selecting the sample and analyzing the data. As a by-product, we show that the
ratio of transition probabilities for the 5007 A and the 4959 A lines is2.99 +-
0.02, in good agreement with (but more accurate than) theoretical estimates. We
compare and contrast the O III emission line method used here with the
Many-Multiplet method that has been used recently to suggest evidence for a
time-dependent alpha. In an Appendix, we have analyzed the larger quasar sample
from the SDSS Data Release One Sample and find Delta alpha/alpha(0) = (1.2 +-
0.7) * 10^{-4}.


title: Speckle Decorrelation and Dynamic Range in Speckle Noise Limited Imaging

abstract:
  The useful dynamic range of an image in the diffraction limited regime is
usually limited by speckles caused by residual phase errors in the optical
system forming the image. The technique of speckle decorrelation involves
introducing many independent realizations of additional phase error into a
wavefront during one speckle lifetime, changing the instantaneous speckle
pattern. A commonly held assumption is that this results in the speckles being
`moved around' at the rate at which the additional phase screens are applied.
The intention of this exercise is to smooth the speckles out into a more
uniform background distribution during their persistence time, thereby enabling
companion detection around bright stars to be photon noise limited rather than
speckle-limited. We demonstrate analytically why this does not occur, and
confirm this result with numerical simulations. We show that the original
speckles must persist, and that the technique of speckle decorrelation merely
adds more noise to the original speckle noise, thereby degrading the dynamic
range of the image.


title: HARM: A Numerical Scheme for General Relativistic Magnetohydrodynamics

abstract:
  We describe a conservative, shock-capturing scheme for evolving the equations
of general relativistic magnetohydrodynamics. The fluxes are calculated using
the Harten, Lax, and van Leer scheme. A variant of constrained transport,
proposed earlier by T\'oth, is used to maintain a divergence free magnetic
field. Only the covariant form of the metric in a coordinate basis is required
to specify the geometry. We describe code performance on a full suite of test
problems in both special and general relativity. On smooth flows we show that
it converges at second order. We conclude by showing some results from the
evolution of a magnetized torus near a rotating black hole.


title: Dark Energy as a Modification of the Friedmann Equation

abstract:
  Dark energy could actually be the manifestation of a modification to the
Friedmann equation arising from new physics (e.g., extra dimensions). Writing
the correction as $(1-\Omega_M)H^\alpha /H_0^{\alpha -2}$, we explore the
phenomenology and detectability of such. We show that: (i) $\alpha$ must be
$\la 1$; (ii) such a correction behaves like dark energy with equation-of-state
$w_{\rm eff} = -1 + {\alpha \over 2}$ in the recent past ($10^4> z\gg 1$) and
$w=-1$ in the distant future and can mimic $w<-1$ without violating the
weak-energy condition; (iii) $w_{\rm eff}$ changes, $dz/dw|_{z\sim 0.5} \sim
{\cal O}(0.2)$, which is likely detectable; and (iv) a future supernova
experiment like SNAP that can determine $w$ with precision $\sigma_w$, could
determine $\alpha$ to precision $\sigma_\alpha \approx 2 \sigma_w$.


title: CO Molecular Gas in Infrared Luminous Galaxies

abstract:
  We present the first statistical survey of the properties of the 12CO(1-0)
and 12CO(3-2) line emission from the nuclei of a nearly complete subsample of
60 infrared (IR) luminous galaxies selected from SCUBA Local Universe Galaxy
Survey (SLUGS). This subsample is flux limited at S60 mincron > 5.24 Jy with
far-IR (FIR) luminosities mostly at LFIR > 10^10 LSUN. We compare the emission
line strengths of 12CO(1-0) and (3-2) transitions at a common resolution of
15". The measured 12CO(3-2) to (1-0) line intensity ratios r31 vary from 0.22
to 1.72 with a mean value of 0.66 for the sources observed, indicating a large
spread of the degree of excitation of CO in the sample. These CO data, together
with a wide range of data at different wavelengths obtained from the
literature, allow us to study the relationship between the CO excitation
conditions and the physical properties of gas/dust and star formation in the
central regions of galaxies. Our analysis shows that there is a non-linear
relation between CO and FIR luminosities, such that their ratio LCO/LFIR
decreases linearly with increasing LFIR. This behavior was found to be
consistent with the Schmidt Law relating star formation rate to molecular gas
content, with an index N = 1.4 +- 0.3. We also find a possible dependence of
the degree of CO gas excitation on the efficiency of star forming activity.
Using the large velocity gradient (LVG) approximation to model the observed
data, we investigate the CO-to-H2 conversion factor X for the SLUGS sample. The
results show that the mean value of X for the SLUGS sample is lower by a factor
of 10 compared to the conventional value derived for the Galaxy, if we assume
the abundance of CO relative to H2, ZCO = 10^-4.


title: Radio/X-ray Offsets of Large Scale Jets Caused by Synchrotron Time Lags

abstract:
  In the internal shock scenario, we argue that electrons in most kpc (or even
larger) scale jets can be accelerated to energies high enough to emit
synchrotron X-rays, if shocks exist on these scales. These high energy
electrons emit synchrotron radiation at high frequencies and cool as they
propagate downstream along the jet, emitting at progressively lower frequencies
and resulting in time lags and hence radio/X-ray (and optical/X-ray if the
optical knot is detectable) offsets at bright knots, with the centroids of
X-ray knots being closer to the core. Taking into account strong effects of jet
expansion, the behaviour of radio/X-ray and optical/X-ray offsets at bright
knots in M87, Cen A, 3C 66B, 3C 31, 3C 273, and PKS 1127-145 is consistent with
that of synchrotron time lags due to radiative losses. This suggests that the
large scale X-ray and optical jets in these sources are due to synchrotron
emission.


title:
The DDO IVC Distance Project: Survey Description and the Distance to
  G139.6+47.6

abstract:
  We present a detailed analysis of the distance determination for one
intermediate Velocity Cloud (IVC G139.6+47.6) from the ongoing DDO IVC Distance
Project. Stars along the line of sight to G139.6+47.6 are examined for the
presence of sodium absorption attributable to the cloud, and the distance
bracket is established by astrometric and spectroscopic parallax measurements
of demonstrated foreground and background stars. We detail our strategy
regarding target selection, observational setup, and analysis of the data,
including a discussion of wavelength calibration and sky subtraction
uncertainties. We find a distance estimate of 129 (+/- 10) pc for the lower
limit and 257 (+211-33) pc for the upper limit. Given the high number of stars
showing absorption due to this IVC, we also discuss the small-scale covering
factor of the cloud and the likely significance of non-detections for
subsequent observations of this and other similar IVC's. Distance measurements
of the remaining targets in the DDO IVC project will be detailed in a companion
paper.


title:
Chandra Observations of a Non-Thermal Supernova Remnant Candidate AX
  J1843.8-0352 and its Surroundings

abstract:
  We present the Chandra results of AX J1843.8-0352, a supernova remnant (SNR)
recently identified with ASCA. Chandra spatially resolved two components from
this SNR: non-thermal and thermal ones. The morphology of the non-thermal
component is clumpy and elliptical, elongated from the north to the south with
a mean diameter of about 9 arcmin. The spectrum is fitted with a power-law
model of photon index 2.1 and the east rim is associated with the non-thermal
radio sources C and F (Helfand et al. 1989). Therefore the non-thermal
component is probably synchrotron X-rays by energetic electrons accelerated at
the shell of the SNR. The thermal component is the brightest clump located
within the non-thermal component and shows a spectrum of a thin plasma of about
0.7 keV temperature. Notable discovery is its peculiar morphology; a head of 50
arcsec x 30 arcsec size near the south-east rim of the SNR and a 30 arcsec-long
``jet'' pointing to the southwest. Although this emission is associated with
the west part of the radio source F, the absorption is twice larger than that
of the non-thermal X-rays, or the bulk of the SNR emission. Therefore, it is
unclear whether this peculiar plasma is a thermal component associated with AX
J1843.8-0352, a Galactic source located in the far side of our Galaxy, or an
extragalactic source.


title:
Diffuse Hard X-ray Sources Discovered with the ASCA Galactic Plane
  Survey

abstract:
  We found diffuse hard X-ray sources, G11.0+0.0, G25.5+0.0, and G26.6-0.1 in
the ASCA Galactic plane survey data. The X-ray spectra are featureless with no
emission line, and are fitted with both models of a thin thermal plasma in
non-equilibrium ionization and a power-law function. The source distances are
estimated to be 1-8 kpc, using the best-fit NH values on the assumption that
the mean density in the line of sight is 1 H cm^-3. The source sizes and
luminosities are then 4.5-27 pc and (0.8-23)x10^33 ergs/s. Although the source
sizes are typical to supernova remnants (SNR) with young to intermediate ages,
the X-ray luminosity, plasma temperature, and weak emission lines in the
spectra are all unusual. This suggests that these objects are either shell-like
SNRs dominated by X-ray synchrotron emission, like SN 1006, or, alternatively,
plerionic SNRs. The total number of these classes of SNRs in our Galaxy is also
estimated.


title:
Explaining the Observed Polarization from Brown Dwarfs by Single Dust
  Scattering

abstract:
  Recent observation of linear optical polarization from brown dwarfs confirms
the dust hypothesis in the atmospheres of brown dwarfs with effective
temperature higher than 1400 K. The observed polarization could arise due to
dust scattering in the rotation induced oblate photosphere or due to the
scattering by non-spherical grains in the spherical atmosphere or by the
anisotropic distribution of dust clouds. Assuming single scattering by
spherical grains in a slightly oblate photosphere consistent with the projected
rotational velocity, the observed optical linear polarization is modeled by
taking grains of different sizes located at different pressure height and of
different number density. Minimum possible oblateness of the object due to
rotation is considered in order to constrain the grain size. It is shown that
the observed polarization from the L-dwarfs 2MASSW J0036+1821 and DENIS-P
J0255-4700 can well be explained by several sets of dust parameters and with
the minimum possible oblateness. Models for the observed polarization constrain
the maximum size of grains. It is emphasized that future observation of
polarization at the blue region will further constrain the grain size.


title:
Non-normal and Stochastic Amplification in Turbulent Dynamo: Subcritical
  Case

abstract:
  Our attention focuses on the stochastic dynamo equation with non-normal
operator that give an insight into the role of stochastics and non-normality in
the galactic magnetic field generation. The main point of this Letter is a
discussion of the generation of a large-scale magnetic field that cannot be
explained by traditional linear eigenvalue analysis. We present a simple
stochastic model for the thin-disk axisymmetric $\alpha \Omega $ dynamo
involving three factors: (a) the non-normality generated by differential
rotation, (b) the nonlinearity reflecting how the magnetic field affects the
turbulent dynamo coefficients, and (c) stochastic perturbations. We show that
even for \textit{subcritical case,} there are three possible mechanisms for the
generation of magnetic field. The first mechanism is a deterministic one that
describes an interplay between transient growth and nonlinear saturation of the
turbulent $\alpha -$effect and diffusivity. It turns out that the trivial state
is nonlinearity unstable to small but finite initial perturbations. The second
and third are the stochastic mechanisms that account for the interaction of
non-normal effect generated by differential rotation and random additive and
multiplicative fluctuations. In particular, we show that in \textit{subcritical
case}the average magnetic energy can grow exponentially with time due to the
multiplicative noise associated with $\alpha -$effect.


title: Chemical changes during star formation: high- versus low-mass YSOs

abstract:
  Recent observational studies of high- and low-mass YSOs at (sub)millimeter
and infrared wavelengths are reviewed, and chemical diagnostics of the
different physical components are summarized. Methods for determining the
temperature, density and abundance profiles in the envelopes are outlined, and
are illustrated for one high-mass and one low-mass YSO. The combination of
(sub)millimeter and infrared data gives a nearly complete chemical inventory of
the gas and solid state material. In both high- and low-mass YSOs, the chemical
characteristics are dominated by freeze-out in the cold outer part of the
envelope and evaporation of ices in the warm inner part. Abundance jumps of
factors of ~100 in selected molecules are found in the warm gas for both types
of objects. Potential differences include (i) the complex hot core chemistry,
which has been observed so far only for high-mass YSOs; (ii) the high level of
deuterium fractionation seen only in low-mass YSOs; (iii) the effects of
internal or external UV and X-rays; (iv) the relative importance of shocks
versus thermal heating of the envelope; and (v) the importance of geometrical
effects.


title: Heavy element abundance patterns in hot DA white dwarfs

abstract:
  We present a series of systematic abundance measurements for 25 hot DA white
dwarfs in the temperature range ~20000-110000K, based on far-UV spectroscopy
with STIS/GHRS on HST, IUE and FUSE. Using our latest heavy element blanketed
non-LTE stellar atmosphere calculations we have addressed the heavy element
abundance patterns making completely objective measurements of abundance values
and upper limits using a 2 fitting technique to determine the uncertainties in
the abundance measurements, which can be related to the formal upper limits in
those stars where particular elements are not detected. We find that the
presence or absence of heavy elements in the hot DA white dwarfs largely
reflects what would be expected if radiative levitation is the supporting
mechanism, although the measured abundances do not match the predicted values
very well, as reported by other authors in the past. Almost all stars hotter
than ~50000K contain heavy elements. For most of these the spread in element
abundances is quite narrow and similar to the abundances measured in G191-B2B.
However, there is an unexplained dichotomy at lower temperatures with some
stars having apparently pure H envelopes and others detectable quantities of
heavy elements. The heavy elements present in these cooler stars are often
stratified, lying in the outermost layers of the envelope. A few strong
temperature/evolutionary effects are seen in the abundance measurements. There
is a decreasing Si abundance with temperature, the N abundance pattern splits
into two groups at lower temperature and there is a sharp decline in Fe and Ni
abundance to zero, below ~50000K. When detected, the Fe and Ni abundances
maintain an approximately constant ratio, close to the cosmic value ~20.


title: Search for Gamma Ray Emission from Galactic Plane with Milagro

abstract:
  The majority of galactic gamma rays are produced by interaction of cosmic
rays with matter or radiation fields. This results in a diffuse radiation
concentrated in the galactic plane where the flux of cosmic rays and the
density of material (mostly atomic, molecular and ionized hydrogen) is high.
The interactions producing gamma rays include, among others, the decay of
pi^{0}'s produced in spallation reactions. Gamma emission from the plane has
indeed been detected in the energy range up to 30 GeV. Above 1 GeV, the
observed intensity is notably higher than expected in simple models, possibly
implying an enhancement at the TeV region as well. Observations at TeV energies
made by Milagro, a large aperture water Cherenkov detector for extensive air
showers, are from a solid angle of more than two steradians in the overhead
sky. An excess has been observed from the region of the Milagro inner Galaxy
defined by 20 < l < 100 and |b| < 5 degrees with the significance 2.3 10^{-4}
using data from 2000-2001 that we attribute to the first evidence for the
diffuse emission at TeV energies. The emission from the region of the Milagro
outer galaxy defined by 140 < l < 220 and |b| < 5 degrees is not inconsistent
with being only that from the cosmic ray background.


title:
Monte Carlo Simulations of Globular Cluster Evolution. III. Primordial
  Binary Interactions

abstract:
  We study the dynamical evolution of globular clusters using our 2D Monte
Carlo code with the inclusion of primordial binary interactions for equal-mass
stars. We use approximate analytical cross sections for energy generation from
binary-binary and binary-single interactions. After a brief period of slight
contraction or expansion of the core over the first few relaxation times, all
clusters enter a much longer phase of stable "binary burning" lasting many tens
of relaxation times. The structural parameters of our models during this phase
match well those of most observed globular clusters. At the end of this phase,
clusters that have survived tidal disruption undergo deep core collapse,
followed by gravothermal oscillations. Our results clearly show that the
presence of even a small fraction of binaries in a cluster is sufficient to
support the core against collapse significantly beyond the normal core collapse
time predicted without the presence of binaries. For tidally truncated systems,
collapse is easily delayed sufficiently that the cluster will undergo complete
tidal disruption before core collapse. As a first step toward the eventual goal
of computing all interactions exactly using dynamical three- and four-body
integration, we have incorporated an exact treatment of binary-single
interactions in our code. We show that results using analytical cross sections
are in good agreement with those using exact three-body integration, even for
small binary fractions where binary-single interactions are energetically most
important.


title: The nature of the absorbing torus in compact Radio Galaxies

abstract:
  We present BeppoSAX observations of the two radio galaxies PKS 1934-63 and S5
1946+708. Strong Iron Kalpha lines are detected in both objects indicating that
the two sources are absorbed by column densities higher than 10^24 cm^(-2).
  Combining radio continuum, HI absorption and X-ray data we can constrain the
physical state and the dimensions of the absorber. We find that the putative
obscuring torus is molecular and located at a distance higher than 20 pc from
the center in S5 1946+70. In PKS 1934-63 no radio nucleus has been observed. If
this is due to free-free absorption a radius of only a few pc is inferred.
Since the Kalpha lines have been detected only at 90% confidence, we also
discuss the implications if they would be not as strong as found from our data.
  From our results it appears that the combination of hard X-ray data and
spatially resolved HI absorption measurements provides a powerful diagnostic
for conditions in the absorbing ``torus''.


title:
Deep optical observations of the fields of two nearby millisecond
  pulsars with the VLT

abstract:
  We report on deep VLT observations of the fields of two nearby, isolated
millisecond pulsars PSR J1744-1134 and PSR J1024-0719. Both objects are old
neutron stars with characteristic age $\tau \ge 10^9$ yr and have relatively
high spin-down flux. They have been detected earlier as X-ray sources by ROSAT
HRI observations and were considered good candidates for non-thermal emission
in the optical bands. Our observations set an upper limit of $B=26.9$, $V=26.3$
and $R=26.0$ for PSR J1744-1134. In the case of PSR J1024-0719, we find two
faint objects near the radio position of the pulsar. Using multi-band
photometry from the VLT and spectroscopy carried out with the Magellan I
telescope, we discuss the nature of the brighter object and the possibility of
the fainter one being the optical counterpart of PSR J1024-0719. We consider
the implications of our findings for both pulsars in the context of theoretical
models of high-energy emission from old pulsars.


title: Embedded disks in Fornax dwarf ellipticals

abstract:
  We present photometric and kinematic evidence for the presence of stellar
disks, seen practically edge-on, in two Fornax dwarf galaxies, FCC204 (dS0(6))
and FCC288 (dS0(7)). This is the first time such structures have been
identified in Fornax dwarfs. FCC2088 has only a small bulge and a bright
flaring and slightly warped disk that can be traced out to 23" from the center
(2.05 kpc for H_0=75 km/s/Mpc). FCC204's disk can be traced out to 20" (1.78
kpc). This galaxy possesses a large bulge. These results can be compared to the
findings of Jerjen et al. (2000) and Barazza et al. (2002) who discovered
nucleated dEs with spiral and bar features in the Virgo Cluster.


title: Propagation velocities of gas rings in collisional ring galaxies

abstract:
  The propagation velocity of the first gas ring in collisional ring galaxies,
i.e. the velocity at which the maximum in the radial gas density profile
propagates radially in the galactic disk, is usually inferred from the radial
expansion velocity of gas in the first ring. Our numerical hydrodynamics
modeling of ring galaxy formation however shows that the maximum radial
expansion velocity of gas in the first ring ($v_{gas}$) is invariably below the
propagation velocity of the first gas ring itself ($v_{ring}$). Modeling of the
Cartwheel galaxy indicates that the outer ring is currently propagating at
$v_{ring} \approx$ 100 km/s, while the maximum radial expansion velocity of gas
in the outer ring is currently $v_{gas} \approx$ 65 km/s. Modeling of the
radial B-V/V-K color gradients of the Cartwheel ring galaxy also indicates that
the outer ring is propagating at $v_{ring} \ge $ 90 km/s. We show that a
combined effect of inclination, finite thickness, and warping of the
Cartwheel's disk might be responsible for the lack of angular difference in the
peak positions found for the azimuthally averaged $H\alpha$, K and B surface
brightness profiles of the Cartwheel's outer ring. Indeed, the radial $H\alpha$
surface brightness profiles obtained along the Cartwheel's major axis, where
effects of inclination and finite thickness are minimized, do peak exterior to
those at K- and B-bands. The angular difference in peak positions implies
$v_{ring}$ = 110 km/s, which is in agreement with the model predictions. We
briefly discuss the utility of radio continuum emission and spectral line
equivalent widths for determining the propagation velocity of gas rings in
collisional ring galaxies.


title:
The Radio Loud / Radio Quiet dichotomy: news from the 2dF QSO Redshift
  Survey

abstract:
  We present a detailed analysis of a sample of radio-detected quasars,
obtained by matching together objects from the FIRST and 2dF Quasar Redshift
Surveys. The dataset consists of 113 sources, spanning a redshift range 0.3 < z
< 2.2, with optical magnitudes 18.25 < b_J < 20.85 and radio fluxes S_{1.4 GHz}
< 1 mJy. These objects exhibit properties such as redshift and colour
distribution in full agreement with those derived for the whole quasar
population, suggestive of an independence of the mechanism(s) controlling the
birth and life-time of quasars of their level of radio emission. The long
debated question of radio-loud (RL)/radio-quiet (RQ) dichotomy is then
investigated for the combined FIRST-2dF and FIRST-LBQS sample, since they
present similar selection criteria. We find the fraction of radio detections to
increase with magnitude from < 3% at the faintest levels up to 20% for the
brightest sources. The classical RL/RQ dichotomy, in which the distribution of
radio-to-optical ratios and/or radio luminosities shows a lack of sources, is
ruled out by our analysis. We also find no tight relationship between optical
and radio luminosities for sources in the considered sample, result that tends
to exclude the mass of the quasar black hole as the physical quantity
associated to the level of radio emission.


title: The size distribution of galaxies in the Sloan Digital Sky Survey

abstract:
  abridged: We use a complete sample of about 140,000 galaxies from the Sloan
Digital Sky Survey (SDSS) to study the size distribution of galaxies and its
dependence on their luminosity, stellar mass, and morphological type. The large
SDSS database provides statistics of unprecedented accuracy. For each type of
galaxy, the size distribution at given luminosity (or stellar mass) is well
described by a log-normal function, characterized by its median $\bar{R}$ and
dispersion $\sigma_{\ln R}$. For late-type galaxies, there is a characteristic
luminosity at $M_{r,0}\sim -20.5$ (assuming $h=0.7$) corresponding to a stellar
mass $M_0\sim 10^{10.6}\Msun$. Galaxies more massive than $M_0$ have
$\bar{R}\propto M^{0.4}$ and $\sigma_{\ln R}\sim 0.3$, while less massive
galaxies have $\bar{R}\propto M^{0.15}$ and $\sigma_{\ln R}\sim 0.5$. For
early-type galaxies, the $\bar{R}$ - $M$ relation is significantly steeper,
$\bar{R}\propto M^{0.55}$, but the $\sigma_{\ln R}$ - $M$ relation is similar
to that of late-type galaxies. Faint red galaxies have sizes quite independent
of their luminosities.


title: Conditions of Dynamical Stability for the HD 160691 Planetary System

abstract:
  The orbits in the HD 160691 planetary system at first appeared highly
unstable, but using the MEGNO and FLI techniques of global dynamics analysis in
the orbital parameter space we have found a stabilizing mechanism that could be
the key to its existence. In order to be dynamically stable, the HD 160691
planetary system has to satisfy the following conditions: (1) a 2:1 mean motion
resonance, combined with (2) an apsidal secular resonance in (3) a
configuration $P_{c}(ap) - S - P_{b}(ap)$ where the two apsidal lines are
anti-aligned, and (4) specific conditions on the respective sizes of the
eccentricities (high eccentricity for the outer orbit is in particular the most
probable necessary condition). More generally, in this original orbital
topology, where the resonance variables $\theta_{1}$ and $\theta_{3}$ librate
about $180^{\circ}$ while $\theta_{2}$ librates about $0^{\circ}$, the HD
160691 system and its mechanism have revealed aspects of the 2:1 orbital
resonances that have not been observed nor analyzed before. The present
topology combined with the 2:1 resonance is indeed more wide-ranging than the
particular case of the HD 160691 planetary system. It is a new theoretical
possibility suitable for a stable regime despite relatively small semi-major
axes with respect to the important masses in interactions.


title: Photometric study of the young open cluster NGC 3293

abstract:
  Deep and extensive CCD photometric observations $UBV(RI)_{C}H_{\alpha}$ were
carried out in the area of the open cluster NGC 3293. The new data set allows
to see the entire cluster sequence down to $M_{V} \approx +4.5$, revealing that
stars with $M_{V} < -2$ are evolving off the main sequence; stars with $-2 <
M_{V} < +2$ are located on the main sequence and stars with $M_{V} > +2$ are
placed above it. According to our analysis, the cluster distance is $d = 2750
\pm 250 pc$ ($V_{0}-M_{V} = 12.2 \pm 0.2$) and its nuclear age is $8 \pm 1
Myr$. NGC 3293 contains an important fraction of pre--main sequence (PMS) stars
distributed along a parallel band to the ZAMS with masses from 1 to $2.5 \cal
M_{\sun}$ and a mean contraction age of $10 Myr$. This last value does not
differ too much from the nuclear age estimate. Actually, if we take into
account the many factors that may affect the PMS star positions onto the
colour--magnitude diagram, both ages can be perfectly reconciled. The star
formation rate, on the other hand, suggests that NGC 3293 stars formed surely
in one single event, therefore favouring a coeval process of star formation.
Besides, using the $H_{\alpha}$ data, we detected nineteen stars with signs of
having $H_{\alpha}$ emission in the region of NGC 3293, giving another
indication that the star formation process is still active in the region. The
computed initial mass function for the cluster has a slope value $x = 1.2 \pm
0.2$, a bit flatter than the typical slope for field stars and similar to the
values found for other young open clusters.


title:
Large Scale Alignment of Optical Polarizations from Distant QSOs using
  Coordinate Invariant Statistics

abstract:
  We introduce several coordinate invariant statistical procedures in order to
test for local alignment of polarizations. A large scale alignment of optical
polarizations from distant QSOs has recently been observed by \huts and
collaborators. The new statistical procedures are based on comparing
polarizations at different angular coordinates by making a parallel transport.
The results of these statistical procedures continue to support the existence
of the large scale alignment effect in the QSO optical polarization data. The
alignment is found to be much more pronounced in the data sample with low
degrees of polarization $p\le 2$%. This suggests that the alignment may be
attributed to some propagation effect. The distance scale over which the
alignment effect is dominant is found to be of order 1 Gpc. We also find that a
very large scale alignment is present in the large redshift, $z\ge 1$, data
sample. Infact the data sample with $z\ge 1$ appears to be aligned over the
entire celestial sphere. We discuss possible physical effects, such as
extinction and pseudoscalar-photon mixing, which may be responsible for the
observations.


title: A Multi-Phase Chemo-Dynamical SPH Code for Galaxy Evolution

abstract:
  In this paper we present some test results of our newly developed Multi-Phase
Chemo-Dynamical Smoothed Particle Hydrodynamics (MP- CD-SPH) code for galaxy
evolution. At first, we present a test of the ``pure'' hydro SPH part of the
code. Then we describe and test the multi-phase description of the gaseous
components of the interstellar matter. In this second part we also compare our
condensation and evaporation description with the results of a previous 2d
multi-phase hydrodynamic mesh code.


title: The distance to the LMC cluster NGC 1866 and the surrounding field

abstract:
  We use the Main Sequence stars in the LMC cluster NGC 1866 and of Red Clump
stars in the local field to obtain two independent estimates of the LMC
distance. We apply an empirical Main Sequence-fitting technique based on a
large sample of subdwarfs with accurate {\sl Hipparcos} parallaxes in order to
estimate the cluster distance modulus, and the multicolor Red Clump method to
derive distance and reddening of the LMC field. We find that the Main
Sequence-fitting and the Red Clump distance moduli are in significant
disagreement; NGC 1866 distance is equal to $\rm (m-M)_{0,NGC
1866}=18.33\pm$0.08 (consistent with a previous estimate using the same data
and theoretical Main Sequence isochrones), while the field stars provide $\rm
(m-M)_{0,field}=18.53\pm$0.07. This difference reflects the more general
dichotomy in the LMC distance estimates found in the literature. Various
possible causes for this disagreement are explored, with particular attention
paid to the still uncertain metallicity of the cluster and the star formation
history of the field stars.


title: Galactic Halos of Fluid Dark Matter

abstract:
  Dwarf spiral galaxies - and in particular the prototypical DDO 154 - are
known to be completely dominated by an unseen component. The putative
neutralinos - so far the favored explanation for the astronomical dark matter -
fail to reproduce the well measured rotation curves of those systems because
these species tend to form a central cusp whose presence is not supported by
observation. We have considered here a self-coupled charged scalar field as an
alternative to neutralinos and investigated whether a Bose condensate of that
field could account for the dark matter inside DDO 154 and more generally
inside dwarf spirals. The size of the condensate turns out to be precisely
determined by the scalar mass m and self-coupling lambda of the field. We find
actually that for m^4 / lambda = 50 - 75 eV^4, the agreement with the
measurements of the circular speed of DDO 154 is impressive whereas it lessens
for larger systems. The cosmological behavior of the field is also found to be
consistent - yet marginally - with the limits set by BBN on the effective
number of neutrino families. We conclude that classical configurations of a
scalar and self-coupled field provide a possible solution to the astronomical
dark matter problem and we suggest further directions of research.


title: A robust algorithm for sky background computation in CCD images

abstract:
  In this paper we present a non-interactive algorithm to estimate a
representative value for the sky background on CCD images. The method we have
devised uses the mode as a robust estimator of the background brightness in
sub-windows distributed across the input frame. The presence of contaminating
objects is detected through the study of the local intensity distribution
function and the perturbed areas are rejected using a statistical criterion
which was derived from numerical simulations. The technique has been
extensively tested on a large amount of images and it is suitable for fully
automatic processing of large data volumes. The implementation we discuss here
has been optimized for the ESO-FORS1 instrument, but it can be easily
generalized to all CCD imagers with a sufficiently large field of view. The
algorithm has been successfully used for the UBVRI ESO-Paranal night sky
brightness survey (Patat 2003).


title: Unipolar Induction of a Magnetized Accretion Disk around a Black Hole

abstract:
  The structure and magnitude of the electromagnetic field produced by a
rotating accretion disk around a black hole were determined. The disk matter is
assumed to be a magnetized plasma with a frozenin poloidal magnetic field. The
vacuum approximation is used outside the disk.


title: Response of distance measures to the equation of state

abstract:
  We show that the distance measures (such as the luminosity and angular
diameter distances) are linear functionals of the equation-of-state function
w(z) of the dark energy to a fair degree of accuracy in the regimes of
interest. That is, the distance measures can be expressed as a sum of (i) a
constant and (ii) an integral of a weighting function multiplied by the
equation of state parameter w(z). The existence of such an accurate linear
response approximation has several important implications: (a) Fitting a
constant w model to the data drawn from an evolving model has a simple
interpretation as a weighted average of w(z). (b) Any polynomial (or other
expansion coefficients can also be expressed as weighted sums of the true w(z).
(c) A replacement for the commonly used heuristic equation for the effective
w(z), as determined by the CMB, can be derived and the result is found to be
quite close to the heuristic expression commonly used. (d) The reconstruction
of w(z) by Huterer et al. (2002) can be expressed as a matrix inversion. In
each case the limitations of the linear response approximation are explored and
found to be surprisingly small.


title: Dark Baryons in Galactic Halos

abstract:
  As is well known, most of the baryons are observationally unaccounted.
Moreover, certain recent developments suggest that dark baryons are mostly
locked up in galactic halos - which are anyway dominated by nonbaryonic dark
matter - and a sizable fraction of them consists of gas clouds. While a priori
various forms of baryonic dark matter in galaxies can be conceived,
observational constraints rule out most of the possibilities, leaving brown
dwarfs and cold gas clouds mostly made of H_2 as the only viable candidates.
So, it looks natural to suppose that baryonic dark matter in galaxies is
accounted for by dark clusters made of brown dwarfs and cold H_2 clouds. We
discuss a realistic dark cluster formation mechanism. We also discuss various
ramifications of the dark cluster scenario in question, paying particular
attention to its observational implications.


title:
A weakly non-adiabatic one-zone model of stellar pulsations: application
  to Mira stars

abstract:
  There is growing observational evidence that the irregular changes in the
light curves of certain variable stars might be due to deterministic chaos.
Supporting these conclusions, several simple models of non-linear oscillators
have been shown to be capable of reproducing the observed complex behaviour. In
this work, we introduce a non-linear, non-adiabatic one-zone model intended to
reveal the factors leading to irregular luminosity variations in some pulsating
stars. We have studied and characterized the dynamical behaviour of the
oscillator as the input parameters are varied. The parametric study implied
values corresponding to stellar models in the family of Long Period Variables
and in particular of Mira-type stars. We draw the attention on certain
solutions that reproduce with reasonable accuracy the observed behaviour of
some peculiar Mira variables.


title: White Dwarf Rotation: Observations and Theory

abstract:
  White dwarfs rotate. The angular momentum in single white dwarfs must
originate early in the life of the star, but also must be modified (and perhaps
severely modified) during the many stages of evolution between birth as a
main--sequence star and final appearance as a white dwarf. Observational
constraints on the rotation of single white dwarf stars come from traditional
spectroscopy and from asteroseismology, with the latter providing hints of
angular velocity with depth. Results of these observational determinations,
that white dwarfs rotate with periods ranging from hours to days (or longer),
tells us that the processes by which angular momentum is deposited and/or
drained from the cores of AGB stars are complex. Still, one can place strong
limits on these processes by considering relatively simple limiting cases for
angular momentum evolution in prior stages, and on subsequent angular momentum
evolution in the white dwarfs. These limiting-case constraints will be reviewed
in the context of the available observations.


title: Embedded Clusters in Molecular Clouds

abstract:
  Stellar clusters are born embedded within giant molecular clouds (GMCs) and
during their formation and early evolution are often only visible at infrared
wavelengths, being heavily obscured by dust. Over the last 15 years advances in
infrared detection capabilities have enabled the first systematic studies of
embedded clusters in galactic molecular clouds. In this article we review the
current state of empirical knowledge concerning these extremely young
protocluster systems. From a survey of the literature we compile the first
extensive catalog of galactic embedded cluster properties. We use the catalog
to construct the mass function and estimate the birthrate for embedded clusters
within roughly 2 Kpc of the Sun. We find that the embedded cluster birthrate
exceeds that of visible open clusters by an order of magnitude or more
indicating a high infant mortality rate for protocluster systems. Less than
4-7% of embedded clusters survive emergence from molecular clouds to become
bound clusters of Pleiades age. The vast majority (90%) of stars that form in
embedded clusters form in rich clusters of 100 or more members with masses in
excess of 50 solar masses. We review the role of embedded clusters in
investigating the nature of the IMF which, in one nearby example, has been
measured over the entire range of stellar and substellar mass, from OB stars to
subsellar objects near the deuterium burning limit. We also review the role
embedded clusters play in the investigation of circumstellar disk evolution and
the important constraints they provide for understanding the origin of
planetary systems. Finally, we discuss current ideas concerning the origin and
dynamical evolution of embedded clusters and the implications for the formation
of bound open clusters.


title:
A New approach for a Galactic Synchrotron Polarized Emission Template in
  the Microwave Range

abstract:
  We present a new approach in modelling the polarized Galactic synchrotron
emission in the microwave range (20-100 GHz), where this radiation is expected
to play the leading role in contaminating the Cosmic Microwave Background (CMB)
data. Our method is based on real surveys and aims at providing the real
spatial distributions of both polarized intensity and polarization angles. Its
main features are the modelling of a polarization horizon to determine the
polarized intensity and the use of starlight optical data to model the
polarization angle pattern. Our results are consistent with several existing
data, and our template is virtually free from Faraday rotation effects as
required at frequencies in the cosmological window.


title:
M75, a Globular Cluster with a Trimodal Horizontal Branch. II. BV
  Photometry of the RR Lyrae Variables

abstract:
  We present new BV CCD photometry, light curves, and ephemerides for 9
previously known, 29 newly detected RR Lyrae variables and one newly detected
variable of an unknown type in the globular cluster M75. The photometry used
for the detection of the additional variables was obtained with the image
subtraction package ISIS. The data were acquired on an observing run in July
1999 and range over 7 observing nights. Estimates of fundamental photometric
parameters are presented including intensity- and magnitude-averaged B and V
magnitudes, magnitude-averaged colors, pulsation periods, and pulsation
amplitudes. The mean period of the RRab variables, <P_ab> = 0.5868 d, and the
number fraction of RRc stars, N_c/N_RR = 0.342, are both large for an
Oosterhoff type I (OoI) globular cluster, suggesting that M75 may be
Oosterhoff-intermediate. Possible conflicts between Oosterhoff-type
determination based on the A_V - logP and A_B - logP diagrams are discussed.
The physical parameters of the RRc and RRab variables, as obtained from Fourier
decomposition of their light curves, do not show any clear deviation from
normal OoI behavior.


title:
The universe evolution as a possible mechanism of formation of galaxies
  and their clusters

abstract:
  The Kepler problem is considered in a space with the
Friedmann--Lemaitre--Robertson--Walker metrics of the expanding universe. The
covariant differential of the Friedmann coordinates (X=a(t)x) is considered as
a possible mechanism of the formation of galaxies and clusters of galaxies. The
cosmic evolution leads to decreasing energy of particles, causing free
particles to be captured in bound states. In this approach the evolution of the
universe plays the role usually inscribed to Cold Dark Matter.


title: New Views of Thermonuclear Bursts

abstract:
  Since the advent of powerful new X-ray observatories, NASA's Rossi X-ray
Timing Explorer (RXTE), the Italian - Dutch BeppoSAX mission, XMM-Newton and
Chandra, a number of entirely new phenomena associated with thermonuclear
burning on neutron stars have been discovered. These include: (i) the discovery
of millisecond (300 - 600 Hz) oscillations during bursts, so called ``burst
oscillations'', (ii) a new regime of nuclear burning on neutron stars which
manifests itself through the generation of hours long flares about once a
decade, now referred to as ``superbursts'',(iii) discoveries of bursts from low
accretion rate neutron stars, and (iv) new evidence for discrete spectral
features from bursting neutron stars. In this article we review our current
understanding of thermonuclear bursts on neutron stars, with a focus on these
new phenomena.


title:
Mini-LANNDD T40: A detector to measure the neutrino-argon cross section
  and the electron-neutrino contamination in the off-axis NuMI beam

abstract:
  We describe a preliminary study of a 40-ton liquid argon TPC based on the
ICARUS method to use in the NuMI near region in line with the LANNDD project.
This reduced-scale detector, called ``Mini-LANNDD T40'', is designed for R&D
purposes and systematic measures on its response. Safety concerns are a key
issue, which will be discussed as well as a preliminary design of the detector.
Adapted as a near or vertex detector in a neutrino beam, the Mini-LANNDD T40 is
capable of observing the electron-neutrino flux in the off-axis beam, a key to
use for measuring $\sin^2 2 \theta_{13}$ in the future, and measuring the low
energy neutrino-argon cross-section, an important piece of information for
future long baseline experiments.


title:
A Holistic Scenario of Turbulent Molecular Cloud Evolution and Control
  of the Star Formation Efficiency. First Tests

abstract:
  We compile a holistic scenario for molecular cloud (MC) evolution and control
of the star formation efficiency (SFE), and present a first set of numerical
tests of it. A {\it lossy} compressible cascade can generate density
fluctuations and further turbulence at small scales from large-scale motions,
implying that the turbulence in MCs may originate from the compressions that
form them. Below a {\it sonic} scale $\ls$, turbulence cannot induce any
further subfragmentation, nor be a dominant support agent against gravity.
Since progressively smaller density peaks contain progressively smaller
fractions of the mass, we expect the SFE to decrease with decreasing $\ls$, at
least when the cloud is globally supported by turbulence. Our numerical
experiments confirm this prediction. We also find that the collapsed mass
fraction in the simulations always saturates below 100% efficiency. This may be
due to the decreased mean density of the leftover interclump medium, which in
real clouds (not confined to a box) should then be more easily dispersed,
marking the ``death'' of the cloud. We identify two different functional
dependences (``modes'') of the SFE on $\ls$, which roughly correspond to
globally supported and unsupported cases. Globally supported runs with most of
the turbulent energy at the largest scales have similar SFEs to those of
unsupported runs, providing numerical evidence of the dual role of turbulence,
whereby large-scale turbulent modes induce collapse at smaller scales. We
tentatively suggest that these modes may correspond to the clustered and
isolated modes of star formation, although here they are seen to form part of a
continuum rather than being separate modes. Finally, we compare with previous
proposals that the relevant parameter is the energy injection scale.


title: Eccentricity Evolution in Simulated Galaxy Clusters

abstract:
  Strong cluster eccentricity evolution for $z \le 0.13$ has appeared in a
variety of observational data sets. We examine the evolution of eccentricity in
simulated galaxy clusters using a variety of simulation methodologies,
amplitude normalizations, and background cosmologies. We do not find find such
evolution for $z < 0.1$ in any of our simulation ensembles. We suggest a
systematic error in the form of a redshift-dependent selection effect in
cluster catalogs or missing physics in cluster simulations important enough to
modify the cluster morphology.


title: LISA data analysis: Source identification and subtraction

abstract:
  The Laser Interferometer Space Antenna (LISA) will operate as an AM/FM
receiver for gravitational waves. For binary systems, the source location,
orientation and orbital phase are encoded in the amplitude and frequency
modulation. The same modulations spread a monochromatic signal over a range of
frequencies, making it difficult to identify individual sources. We present a
method for detecting and subtracting individual binary signals from a data
stream with many overlapping signals.


title: The Power Spectra of Two Classes of Long-duration Gamma-ray Bursts

abstract:
  We have studied the averaged power density spectra (PDSs) of two classes of
long-duration gamma-ray bursts in the recent classification by Balastegui et
al.(2001) based on neural network analysis. Both PDSs follow a power law over a
wide frequency range with approximately the same slope, which indicates that a
process with a self-similar temporal property may underlie the emission
mechanisms of both. The two classes of bursts are divided into groups according
to their brightness and spectral hardness respectively and each group's PDS was
calculated; For both classes, the PDS is found to flatten both with increasing
burst brightness and with increasing hardness.


title: Globular Cluster Distances from RR Lyrae Stars

abstract:
  The most common methods to derive the distance to globular clusters using RR
Lyrae variables are reviewed, with a special attention to those that have
experienced significant improvement in the past few years. From the weighted
average of these most recent determinations the absolute magnitude of the RR
Lyrae stars at [Fe/H]=-1.5 is Mv = 0.59 +/- 0.03 mag, corresponding to a
distance modulus for the LMC (m-M)o = 18.48 +/- 0.05.


title: Small-scale clumps in the galactic halo and dark matter annihilation

abstract:
  Production of small-scale DM clumps is studied in the standard cosmological
scenario with an inflation-produced primeval fluctuation spectrum. Special
attention is given to three following problems: (i) The mass spectrum of
small-scale clumps with $M \lesssim 10^3 M_{\odot}$ is calculated with tidal
destruction of the clumps taken into account within the hierarchical model of
clump structure. Only 0.1 - 0.5% of small clumps survive the stage of tidal
destruction in each logarithmic mass interval $\Delta\ln M\sim1$. (ii) The mass
distribution of clumps has a cutoff at $M_{\rm min}$ due to diffusion of DM
particles out of a fluctuation and free streaming at later stage. $M_{\rm min}$
is a model dependent quantity. In the case the neutralino, considered as a pure
bino, is a DM particle, $M_{\rm min} \sim 10^{-8} M_{\odot}$. (iii) The
evolution of density profile in a DM clump does not result in the singularity
because of formation of the core under influence of tidal interaction. The
radius of the core is $R_c \sim 0.1 R$, where $R$ is radius of the clump. The
applications for annihilation of DM particles in the Galactic halo are studied.
The number density of clumps as a function of their mass, radius and distance
to the Galactic center is presented. The enhancement of annihilation signal due
to clumpiness, valid for arbitrary DM particles, is calculated. In spite of
small survival probability, the annihilation signal in most cases is dominated
by clumps. For observationally preferable value of index or primeval
fluctuation spectrum $n_p \approx 1$, the enhancement of annihilation signal is
described by factor 2 - 5 for different density profiles in a clump.


title:
Are the Faraday Rotating Magnetic Fields Local to Intracluster Radio
  Galaxies?

abstract:
  We investigate the origin of the high Faraday rotation measures (RMs) found
for polarized radio galaxies in clusters. The two most likely origins are,
magnetic fields local to the source, or magnetic fields located in the
foreground intra-cluster medium (ICM). The latter is identified as the null
hypothesis. Rudnick & Blundell (2003) have recently suggested that the presence
of magnetic fields local to the source may be revealed in correlations of the
position angles (PAs) of the source intrinsic linear polarization and the RMs.
We investigate the claim of Rudnick & Blundell to have found a relationship
between the intrinsic PA0 of the radio source PKS 1246-410 and its RM, by
testing the clustering strength of the PA0-RM scatter plot. We show that the
claimed relationship is an artifact of an improperly performed null-experiment.
We describe a gradient alignment statistic aimed at finding correlations
between PA0 and RM maps. This statistic does not require any null-experiment
since it gives a unique (zero) result in the case of uncorrelated maps. We
apply it to a number of extended radio sources in galaxy clusters (PKS
1246-410, Cygnus A, Hydra A, and 3C465). In no case is a significant
large-scale alignment of PA0 and RM maps detected. We find significant
small-scale co-alignment in all cases, but we are able to fully identify this
with map making artifacts through a suitable statistical test. We conclude that
there is presently no existing evidence for Faraday rotation local to radio
lobes. Given the existing independent pieces of evidence, we favor the null
hypothesis that the observed Faraday screens are produced by intracluster
magnetic fields.


title: Characteristic Variability Time Scales of Long Gamma-Ray Bursts

abstract:
  We determined the characteristic variability time scales (\Delta t_p) of 410
bright and long GRBs, by locating the peaks of their Power Density Spectra,
defined and calculated in the time domain. We found that the averaged
variability time scale decreases with the peak flux. This is consistent with
the time-dilation effect expected for the cosmological origin of GRBs. We also
found that the occurrence distribution of the characteristic variability time
scale shows bimodality, which might be interpreted as that the long GRB sample
is composed of two sub-classes with different variability time scales. However,
we found no difference for some other characteristics of these two sub-classes.


title: Doppler Modulation of X-ray lines in Cygnus X-3

abstract:
  We measured Doppler shifts of three bright spectral lines in the X-ray
emission from Cygnus X-3 as recorded by the Chandra X-Ray Observatory. Doppler
shifts of lines associated with Si XIV and S XVI exhibit orbital modulation.
The magnitude and phasing of this modulation relative to the orbital ephemeris
indicate the location of the source of this emission within the wind emanating
from the compact object's companion. These observations enable us to make an
indirect measurement of the separation of the two stars. Under certain
assumptions our observation of a line associated with Fe XXV also limits the
mass of the compact object M < 3.6 MSun.


title: The resolved fraction of the Cosmic X-ray Background

abstract:
  We present the X-ray source number counts in two energy bands (0.5-2 and 2-10
keV) from a very large source sample: we combine data of six different surveys,
both shallow wide field and deep pencil beam, performed with three different
satellites (ROSAT, Chandra and XMM-Newton). The sample covers with good
statistics the largest possible flux range so far: [2.4*10^-17 - 10^-11] cgs in
the soft band and [2.1*10^-16 - 8*10^{-12}]cgs in the hard band. Integrating
the flux distributions over this range and taking into account the (small)
contribution of the brightest sources we derive the flux density generated by
discrete sources in both bands. After a critical review of the literature
values of the total Cosmic X--Ray Background (CXB) we conclude that, with the
present data, the 94.3%, and 88.8% of the soft and hard CXB can be ascribed to
discrete source emission. If we extrapolate the analytical form of the Log
N--Log S distribution beyond the flux limit of our catalog in the soft band we
find that the flux from discrete sources at ~3*10^-18 cgs is consistent with
the entire CXB, whereas in the hard band it accounts for only 93% of the total
CXB at most, hinting for a faint and obscured population to arise at even
fainter fluxes.


title: Stopping inward planetary migration by a toroidal magnetic field

abstract:
  We calculate the linear torque exerted by a planet on a circular orbit on a
disc containing a toroidal magnetic field. All fluid perturbations are singular
at the so--called magnetic resonances, where the Doppler shifted frequency of
the perturbation matches that of a slow MHD wave propagating along the field
line. These lie on both sides of the corotation radius. Waves propagate outside
the Lindblad resonances, and also in a restricted region around the magnetic
resonances. The magnetic resonances contribute to a significant global torque
which, like the Lindblad torque, is negative (positive) inside (outside) the
planet's orbit. Since these resonances are closer to the planet than the
Lindblad resonances, the torque they contribute dominates over the Lindblad
torque if the magnetic field is large enough. In addition, if beta=c^2/v_A^2
increases fast enough with radius, the outer magnetic resonance becomes less
important and the total torque is then negative, dominated by the inner
magnetic resonance. This leads to outward migration of the planet. Even for
beta=100 at corotation, a negative torque may be obtained. A planet migrating
inward through a nonmagnetized region of a disc would then stall when reaching
a magnetized region. It would then be able to grow to become a terrestrial
planet or the core of a giant planet. In a turbulent magnetized disc in which
the large scale field structure changes sufficiently slowly, a planet may
alternate between inward and outward migration, depending on the gradients of
the field encountered. Its migration could then become diffusive, or be limited
only to small scales.


title: Two Types of X-ray Spectra in Cataclysmic Variables

abstract:
  We present Chandra HETG spectra of seven cataclysmic variables. We find that
they divide unambiguously into two distinct types. Spectra of the first type
are remarkably well fit by a simple cooling flow model, which assumes only
steady-state isobaric radiative cooling. The maximum temperature and the
normalization, which provides a highly precise measurement of the accretion
rate, are the only free parameters of this model. Spectra of the second type
are grossly inconsistent with a cooling flow model. They instead exhibit a hard
continuum, and show strong H-like and He-like ion emission but little Fe
L-shell emission, which is consistent with expectations for line emission from
a photoionized plasma. Using a simple photoionization model, we argue that the
observed line emission for these sources can be driven entirely by the hard
continuum. The physical significance of these two distinct types of X-ray
spectra is also explored.


title: A Full-Sky H-alpha Template for Microwave Foreground Prediction

abstract:
  A full-sky H-alpha map with 6 arcmin (FWHM) resolution is presented. This map
is a composite of the Virginia Tech Spectral line Survey (VTSS) in the north
and the Southern H-Alpha Sky Survey Atlas (SHASSA) in the south. The Wisconsin
H-Alpha Mapper (WHAM) survey provides a stable zero-point over 3/4 of the sky
on a 1 degree scale. This composite map can be used to provide limits on
thermal bremsstrahlung (free-free emission) from ionized gas known to
contaminate microwave-background data. The map is available on the WWW for
public use.


title: The PSCz Galaxy Power Spectrum Compared to N-Body Simulations

abstract:
  By comparing the PSCz galaxy power spectrum with haloes from nested and
phased N-body simulations, we try to understand how IRAS infrared-selected
galaxies populate dark-matter haloes. We pay special attention to the way we
identify haloes in the simulations.


title:
Indicators of Black Hole Mass and Eddington Accretion Ratio from QSO
  X-ray and UV Spectra

abstract:
  The evolution of luminous QSOs is linked to the evolution of massive
galaxies. We know this because the relic black-holes found locally have masses
dependent on the properties of the host galaxy's bulge. An important way to
explore this evolution would be to measure dependences of black hole masses and
Eddington accretion ratios over a range of redshifts, i.e., with cosmological
age. For low redshift QSOs (and their lower luminosity Seyfert galaxy
counterparts) it has been possible to infer black hole masses from the
luminosities and velocity dispersions of their host-galaxy bulges. These masses
agree with those virial black hole masses calculated from the Doppler widths of
the broad Hbeta emission lines. The latter method can then be extended to more
distant and luminous QSOs, up to redshifts of 0.6 with ground-based optical
observations. We discuss ways to extend these explorations to higher redshifts
-- up to about 3 using the widths of QSOs' broad UV emission lines, and in
principle, and to redshifts near 4 from ground-based infrared observations of
rest-frame Hbeta at 2.5 micron. We discuss the possibility of investigating the
accretion history of the higher redshift QSOs using measures of Eddington
accretion ratio -- the soft X-ray spectral index and the eigenvectors of
Principal Components Analyses of QSOs' UV emission-line spectra.


title: Migration and Dynamical Relaxation in Crowded Systems of Giant Planets

abstract:
  This paper explores the intermediate-time dynamics of newly formed solar
systems with a focus on possible mechanisms for planetary migration. We
consider two limiting corners of the available parameter space -- crowded
systems containing N=10 giant planets in the outer solar system, and solar
systems with N=2 planets that are tidally interacting with a circumstellar
disk. For a given set of initial conditions, dynamical relaxation leads to a
well-defined distribution of possible solar systems. For each class of initial
conditions, we perform large numbers of N-body simulations to obtain a
statistical description of the possible outcomes. For N=10 planet systems, we
consider several different planetary mass distributions; we also perform
secondary sets of simulations to explore chaotic behavior and longer term
dynamical evolution. For systems with 10 planets initially populating the
radial range 5 - 30 AU, these scattering processes naturally produce planetary
orbits with $a\sim1$ AU and the full range of possible eccentricity, but
shorter period orbits are difficult to achieve. To account for the observed
eccentric giant planets, we also explore a mechanism that combines dynamical
scattering and tidal interactions with a circumstellar disk. This combined
model naturally produces the observed range of semi-major axis and
eccentricity. We discuss the relative merits of the different migration
mechanisms for producing the observed eccentric giant planets.


title: Direct Wavelet Expansion of the Primordial Power Spectrum

abstract:
  In order to constrain and possibly detect unusual physics during inflation,
we allow the power spectrum of primordial matter density fluctuations,
P_{in}(k), to be an arbitrary function in the estimation of cosmological
parameters from data. The multi-resolution and good localization properties of
orthogonal wavelets make them suitable for detecting features in P_{in}(k). We
expand P_{in}(k) directly in wavelet basis functions. The likelihood of the
data is thus a function of the wavelet coefficients of P_{in}(k), as well as
the H_0, \Omega_b h^2, $\Omega_c h^2 and the \tau_{ri}, in a flat $\Lambda$CDM
cosmology. We derive constraints on these parameters from CMB anisotropy data
(WMAP, CBI, and ACBAR) and large scale structure (LSS) data (2dFGRS and PSCZ)
using the Markov Chain Monte Carlo (MCMC) technique. The direct wavelet
expansion method is different and complimentary to the wavelet band power
method of Mukherjee & Wang (2003a,b), and results from the two methods are
consistent. In addition, as we demonstrate, the direct wavelet expansion method
has the advantage that once the wavelet coefficients have been constrained, the
reconstruction of P_{in}(k) can be effectively denoised, i.e., P_{in}(k) can be
reconstructed using only the coefficients that, say, deviate from zero at
greater than 1\sigma. In doing so the essential properties of P_{in}(k) are
retained. The reconstruction also suffers much less from the correlated errors
of binning methods. The shape of the primordial power spectrum, as
reconstructed in detail here, reveals an interesting new feature at 0.001 \la
k/{Mpc}^{-1} \la 0.005. It will be interesting to see if this feature is
confirmed by future data. The reconstructed and denoised P_{in}(k) is favored
over the scale-invariant and power-law forms at \ga 1\sigma.


title: Point sources in the MAP sky maps

abstract:
  We discuss point sources foregrounds for the MAP experiment. We consider
several possible strategies for removing them and we assess how the statistics
of the CMB signal are affected by the residual sources. Assuming a power law
distribution for the point sources, we propose a method aimed to determine the
slope of the distribution from the analysis of the moments of the observed
maps. The same method allows for a determination of the underlying CMB
variance. We conclude that the best strategy for point sources finding is the
simultaneous thresholding of the filtered map at all frequencies, with a
relatively low threshold. With this strategy, we expect to find 70 (95)% of the
sources above 3 (4) $\sigma$. Assuming the most conservative case for point
sources detection, the recovered slope of the point sources distribution is
$2.55 \pm 0.15$, for a fiducial $n=2.5$ value. The recovered CMB pus noise map
variance is within 0.2% from the real one, with a standard deviation of $0.31
%$, while Cosmic variance contributes 2.2% to the same CMB plus noise map.


title:
The optical/near-IR spectral energy distribution of the GRB 000210 host
  galaxy

abstract:
  We report on UBVRIZJsHKs-band photometry of the dark GRB 000210 host galaxy.
Fitting a grid of spectral templates to its Spectral Energy Distribution (SED),
we derived a photometric redshift (z=0.842\+0.0540.042) which is in excellent
agreement with the spectroscopic one (z=0.8463+/-0.0002; Piro et al. 2002). The
best fit to the SED is obtained with a blue starburst template with an age of
0.181\+0.0370.026 Gyr. We discuss the implications of the inferred low value of
Av and the age of the dominant stellar population for the non detection of the
GRB 000210 optical afterglow.


title:
Photometric study of new southern SU UMa-type dwarf novae - II:
  Authentication of BF Ara as a Normal SU UMa-type Dwarf Nova with the Shortest
  Supercycle

abstract:
  We photometrically observed the 2002 August long outburst of BF Ara. The
observation for the first time unambiguously detected superhumps (average
period 0.08797(1) d), qualifying BF Ara as a genuine SU UMa-type dwarf nova. An
analysis of the long-term visual light curve yielded a mean supercycle length
of 84.3(3) d. The characteristics of outbursts and superhumps more resemble
those of usual SU UMa-type dwarf novae rather than those of ER UMa stars. BF
Ara is thus confirmed to be the usual SU UMa-type dwarf nova with the shortest
known supercycle length. There still remains an unfilled gap of distributions
between ER UMa stars and usual SU UMa-type dwarf novae. We detected a zero
period change of the superhumps, which is quite unexpected from our previous
knowledge. This discovery implies that a previous interpretation requiring a
low M-dot would be no longer valid, or that a different mechanism is
responsible for BF Ara. We propose that the reduced (prograde) apsidal motion
of the eccentric disk by pressure forces may be responsible for the unusual
period change in BF Ara.


title:
Fine-structure constant variability: surprises for laboratory atomic
  spectroscopy and cosmological evolution of quasar spectra

abstract:
  Calculation of the Dirac hydrogen atom spectrum in the framework of dynamical
fine structure constant (alpha) variability discloses a small departure in the
laboratory from Sommerfeld's formula for the fine structure shifts, possibly
measurable today. And for a distant object in the universe, the wavelength
shift of a spectral line specifically ascribable to cosmological alpha
variation is found to depend differently on the quantum numbers than in the
conventional view. This last result clashes with the conventional wisdom that
an atom's spectrum can change with cosmological time only through evolution of
the alpha parameter in the energy eigenvalue formula, and thus impacts on the
Webb group's analysis of fine structure intervals in quasar absorption lines
(which has been claimed to disclose cosmological alpha evolution). In
particular, analyzing together a mix of quasar absorption lines from different
fine structure multiplets can bias estimates of cosmological alpha variability.

categories: astro-ph gr-qc hep-th physics.atom-ph quant-ph


title:
Evolution of Cosmological Density Distribution Function from the Local
  Collapse Model

abstract:
  We present a general framework to treat the evolution of one-point
probability distribution function (PDF) for cosmic density $\delta$ and
velocity-divergence fields $\theta$. In particular, we derive an evolution
equation for the one-point PDFs and consider the stochastic nature associated
with these quantities. Under the local approximation that the evolution of
cosmic fluid fields can be characterized by the Lagrangian local dynamics with
finite degrees of freedom, evolution equation for PDFs becomes a closed form
and consistent formal solutions are constructed. Adopting this local
approximation, we explicitly evaluate the one-point PDFs $P(\delta)$ and
$P(\theta)$ from the spherical and the ellipsoidal collapse models as the
representative Lagrangian local dynamics. In a Gaussian initial condition,
while the local density PDF from the ellipsoidal model almost coincides with
the that of the spherical model, differences between spherical and ellipsoidal
collapse model are found in the velocity-divergence PDF. Importantly, the joint
PDF of local density, $P(\delta,t;\delta',t')$, evaluated at the same
Lagrangian position but at the different times $t$ and $t'$ from the
ellipsoidal collapse model exhibits a large amount of scatter. The mean
relation between $\delta$ and $\delta'$ does fail to match the one-to-one
mapping obtained from spherical collapse model. Moreover, the joint PDF
$P(\delta;\theta)$ from the ellipsoidal collapse model shows a similar
stochastic feature, both of which are indeed consistent with the recent result
from N-body simulations.


title:
Primordial black holes in braneworld cosmologies: astrophysical
  constraints

abstract:
  In two recent papers we explored the modifications to primordial black hole
physics when one moves to the simplest braneworld model, Randall--Sundrum type
II. Both the evaporation law and the cosmological evolution of the population
can be modified, and additionally accretion of energy from the background can
be dominant over evaporation at high energies. In this paper we present a
detailed study of how this impacts upon various astrophysical constraints,
analyzing constraints from the present density, from the present high-energy
photon background radiation, from distortion of the microwave background
spectrum, and from processes affecting light element abundances both during and
after nucleosynthesis. Typically, the constraints on the formation rate of
primordial black holes weaken as compared to the standard cosmology if black
hole accretion is unimportant at high energies, but can be strengthened in the
case of efficient accretion.


title: Water ice growth around evolved stars

abstract:
  We present a model of the growth of water ice on silicate grains in the
circumstellar envelopes of Asymptotic Giant Branch (AGB) stars and Red Super
Giants. We consider the growth of ice by gas grain collisions, the thermal
evaporation of ice from a grain, and sputtering. Our model contains several
improvements compared to earlier models, including a detailed treatment of the
effects of sputtering, a detailed calculation of the radiation pressure on the
grain, and the treatment of subsonic drift velocities. In terms of drift
velocity between the grains and gas in the envelope, we find that the ice
formation process can be divided into three regimes: (i) a sputtering dominated
regime where ice growth is heavily suppressed, (ii) an intermediate regime with
moderately efficient condensation and (iii) a thermally dominated regime where
ice formation is highly efficient. Sputtering is the critical factor which
determines if ice formation can occur at all. We find that in Red Supergiants,
ice formation is suppressed, while the winds of OH/IR stars allow for efficient
condensation and can convert significant fractions of the available water vapor
(tens of percent) into ice mantles on grains. Population II AGB stars hardly
form ice due to their low dust to gas ratios. We also modify an analytical
equation describing condensation and depletion (Jura and Morris, 1985) in order
to give reasonable results for high and low drift velocities. Initially, ice
will condense in crystalline form, but continuing condensation at low
temperatures, and damage caused by interstellar UV photons favor the production
of amorphous ice as well. We predict that a significant fraction of the ice
formed will be amorphous.


title: Blobby accretion in magnetic cataclysmic variables

abstract:
  The processes of accretion of the gaseous blobs with different masses and
densities onto strongly magnetized white dwarfs in the systems of polars have
been modeled. We have proved that shot noise in blue wavelengths represents
accretion of the smaller and denser blobs than in redder wavelengths. Using
combined "smooth particle hydrodynamics - drag force" model, we have predicted
a shape of the accretion stream and active regions on the white dwarf surface.


title: Detection of DCO+ in a circumstellar disk

abstract:
  We report the first detection of DCO+ in a circumstellar disk. The DCO+ J=5-4
line at 360.169 GHz is observed with the 15m James Clerk Maxwell Telescope in
the disk around the pre-main sequence star TW Hya. Together with measurements
of the HCO+ and H13CO+ J=4-3 lines, this allows an accurate determination of
the DCO+/HCO+ ratio in this disk. The inferred value of 0.035+-0.015 is close
to that found in cold pre-stellar cores and is somewhat higher than that
measured in the envelope around the low-mass protostar IRAS 16293 -2422. It is
also close to the DCN/HCN ratio obtained for pristine cometary material in the
jet of comet Hale-Bopp. The observed DCO+/HCO+ ratio for TW Hya is consistent
with theoretical models of disks which consider gas-phase fractionation
processes within a realistic 2-D temperature distribution and which include the
effects of freeze-out onto grains.


title: The Active Quiescence of HR Del (Nova Del 1967)

abstract:
  This new UV study of the ex-nova HR Del is based on all of the data obtained
with the IUE satellite, and includes the important series of spectra taken in
1988 and 1992 that have not been analyzed so far. After the correction for the
reddening (EB-V)=0.16), adopting a distance d =850 pc, we have derived a mean
UV luminosity close to Luv ~ 56 Lsun, the highest value among classical novae
in "quiescence". Also the "average" optical absolute magnitude Mv=+2.30 is
indicative of a bright object. The UV continuum luminosity, the HeII 1640 A
emission line luminosity, and the optical absolute magnitude all give a mass
accretion rate Mdot very close to 1.4*10**(-7) Msun/yr, if one assumes that the
luminosity of the old nova is due to a non-irradiated accretion disk. The
continuum distribution is well fitted with either a black body of 33,900 K, or
a power-law F(lambda) ~ lambda**(-2.20). We show that the "quiescent" optical
magnitude at mv ~ 12 comes from the hot component and not from the companion
star. Since most IUE observations correspond to the "quiescent" magnitude at mv
~ 12, the same as in the pre-eruption stage, we infer that the pre-nova, for at
least 70 years prior to eruption, was also very bright at near the same Luv,
Mv, Mdot and T values as derived in the present study for the ex-nova. The wind
components in the P Cyg profiles of the CIV 1550 A and NV 1240 A resonance
lines are strong and variable on short timescales, with vedge up to -5000 km/s,
a remarkably high value. The phenomenology in the short-time variations of the
wind indicates the presence of an inhomogeneous outflow. We discuss the nature
of the strong UV continuum and wind features and the implications of the
presence of a "bright" state a long time before and after outburst on our
present knowledge of the pre-nova and post-nova behavior.


title:
Light Propagation in the Gravitational Field of Moving Bodies by means
  of Lorentz Transformation. I. Mass monopoles moving with constant velocities

abstract:
  We show how to derive the equations of light propagation in the gravitational
field of uniformly moving mass monopoles without formulating and integrating
the differential equations of light propagation in that field. The well-known
equations of light propagation in the gravitational field of a motionless mass
monopole are combined with a suitable Lorentz transformation. The possibility
to generalize this technique for the more complicated case of uniformly moving
body of arbitrary multipole structure is discussed.


title: Planets orbiting Quark Nova compact remnants

abstract:
  We explore planet formation in the Quark Nova scenario. If a millisecond
pulsar explodes as a Quark Nova, a protoplanetary disk can be formed out of the
metal rich fall-back material. The propeller mechanism transfers angular
momentum from the born quark star to the disk that will go through viscous
evolution with later plausible grain condensation and planet formation. As a
result, earth-size planets on circular orbits may form within short radii from
the central quark star. The planets in the PSR1257+12 system can be explained
by our model if the Quark Nova compact remnant is born with a period of $\sim
0.5$ ms following the explosion. We suggest that a good portion of the Quark
Nova remnants may harbour planetary systems.


title: Ultra-high energy cosmic rays from Quark Novae

abstract:
  We explore acceleration of ions in the Quark Nova (QN) scenario, where a
neutron star experiences an explosive phase transition into a quark star (born
in the propeller regime). In this picture, two cosmic ray components are
isolated: one related to the randomized pulsar wind and the other to the
propelled wind, both boosted by the ultra-relativistic Quark Nova shock. The
latter component acquires energies $10^{15} {\rm eV}<E<10^{18} {\rm eV}$ while
the former, boosted pulsar wind, achieves ultra-high energies $E> 10^{18.6}$
eV. The composition is dominated by ions present in the pulsar wind in the
energy range above $10^{18.6}$ eV, while at energies below $10^{18}$ eV the
propelled ejecta, consisting of the fall-back neutron star crust material from
the explosion, is the dominant one. Added to these two components, the
propeller injects relativistic particles with Lorentz factors $\Gamma_{\rm
prop.} \sim 1-1000$, later to be accelerated by galactic supernova shocks. The
QN model appears to be able to account for the extragalactic cosmic rays above
the ankle and to contribute a few percent of the galactic cosmic rays below the
ankle. We predict few hundred ultra-high energy cosmic ray events above
$10^{19}$ eV for the Pierre Auger detector per distant QN, while some thousands
are predicted for the proposed EUSO and OWL detectors.


title: Clusters of galaxies in radio

abstract:
  Recent results on the radio emission from galaxy clusters are reviewed, with
emphasis both on the radio galaxies and on the diffuse radio emission from the
intracluster medium. We show that the formation of the tailed morphology in
cluster radio galaxies is due to the effect of the cluster gaseous environment
and of its large scale motions in merging clusters. From Chandra X-ray data, it
has also become evident that the gas in the hot cluster atmospheres may be
displaced by the relativistic plasma. The statistical characteristics of radio
galaxies are briefly discussed, and are shown to be surprisingly similar for
sources both inside and outside rich clusters. The study of diffuse radio
sources originating from the intracluster medium (halos and relics) has
presently become a major area of investigation. Halos and relics are detected
in massive X-ray luminous clusters which are undergoing violent merger
processes. The power of radio halos is correlated with the cluster X-ray
luminosity and mass.


title: An Extended Burst Tail from SGR 1900+14 with a Thermal X-ray Spectrum

abstract:
  The Soft Gamma Repeater, SGR 1900+14, entered a new phase of activity in
April 2001 initiated by the intermediate flare recorded on April 18. Ten days
following this flare, we discovered an abrupt increase in the source flux
between consecutive RXTE orbits. This X-ray flux excess decayed over the next
several minutes and was subsequently linked to a high fluence burst from SGR
1900+14 recorded by other spacecraft (Ulysses and KONUS) while the SGR was
Earth-occulted for RXTE. We present here spectral and temporal analysis of both
the burst of 28 April and the long X-ray tail following it. We find strong
evidence of an exclusively thermal X-ray tail in this event and bring this
evidence to bear on other bursts and flares from SGR 1900+14 which have shown
extended X-ray excesses (e.g. 1998 August 29). We include in this comparison a
discussion of the physical origins of SGR bursts and extended X-ray tails.


title: P-Stars

abstract:
  P-Stars are a new class of compact stars made of up and down quarks in
beta-equilibrium with electrons in an Abelian chromomagnetic condensate. We
show that P-Stars are able to account for compact stars with R < 6 Km, as well
as stars with radius comparable with canonical Neutron Stars. We find that
cooling curves of P-Stars compare rather well with observational data. We
suggest that P-Matter produced at the primordial deconfinement transition is a
viable candidate for baryonic Cold Dark Matter. Finally, we show that P-Stars
are able to overcome the gravitational collapse even for mass much greater than
10^6 Solar Mass.


title:
Reprocessing the Hipparcos data for evolved stars III Revised Hipparcos
  period-luminosity relationship for galactic long-period variable stars

abstract:
  We analyze the K band luminosities of a sample of galactic long-period
variables using parallaxes measured by the Hipparcos mission. The parallaxes
are in most cases re-computed from the Hipparcos Intermediate Astrometric Data
using improved astrometric fits and chromaticity corrections. The K band
magnitudes are taken from the literature and from measurements by COBE, and are
corrected for interstellar and circumstellar extinction. The sample contains
stars of several spectral types: M, S and C, and of several variability
classes: Mira, semiregular SRa, and SRb. We find that the distribution of stars
in the period-luminosity plane is independent of circumstellar chemistry, but
that the different variability types have different P-L distributions. Both the
Mira variables and the SRb variables have reasonably well-defined
period-luminosity relationships, but with very different slopes. The SRa
variables are distributed between the two classes, suggesting that they are a
mixture of Miras and SRb, rather than a separate class of stars. New
period-luminosity relationships are derived based on our revised Hipparcos
parallaxes. The Miras show a similar period-luminosity relationship to that
found for Large Magellanic Cloud Miras by Feast et al. (1989). The maximum
absolute K magnitude of the sample is about -8.2 for both Miras and
semi-regular stars, only a little fainter than the expected AGB limit. We show
that the stars with the longest periods (P>400d) have high mass loss rates and
are almost all Mira variables.


title: The origin of Scorpius X-1

abstract:
  We have used multi-wavelength observations of high precision to derive the
space velocity and compute the orbit around the Galactic Centre of the
prototype X-ray binary Scorpius X-1. An origin in the local spiral arm of the
Milky Way is ruled out. The galactocentric kinematics of Scorpius X-1 is
similar to that of the most ancient stars and globular clusters of the inner
Galactic halo. Most probably, this low-mass X-ray binary was formed by a close
encounter in a globular cluster. However, it cannot be ruled out that a natal
supernova explosion launched Scorpius X-1 into an orbit like this from a birth
place in the galactic bulge. In any case, the Galactocentric orbit indicates
that Scorpius X-1 was formed more than 30 Myrs ago.


title:
Galactic Foreground Constraints from the Python V Cosmic Microwave
  Background Anisotropy Data

abstract:
  We constrain Galactic foreground contamination of the Python V cosmic
microwave background anisotropy data by cross correlating it with foreground
contaminant emission templates. To model foreground emission we use 100 and 12
$\mu$m dust emission templates and two point source templates based on the PMN
survey. The analysis takes account of inter-modulation correlations in 8
modulations of the data that are sensitive to a large range of angular scales
and also densely sample a large area of sky. As a consequence the analysis here
is highly constraining. We find little evidence for foreground contamination in
an analysis of the whole data set. However, there is indication that
foregrounds are present in the data from the larger-angular-scale modulations
of those Python V fields that overlap the region scanned earlier by the UCSB
South Pole 1994 experiment. This is an independent consistency cross-check of
findings from the South Pole 1994 data.


title: The Spin-Up Rate of the White Dwarf of GK Per

abstract:
  We use hard X-ray light curves measured by the Chandra HETG and RXTE PCA
during the late rise and plateau phases of the 2002 March-April outburst of the
intermediate polar GK Per to determine that its X-ray pulse period P = 351.332
+/- 0.002 s. Combined with previous X-ray and optical measurements of the spin
period of the white dwarf, we find that its spin-up rate Pdot = 0.00027 +/-
0.00005 s/yr.


title:
Tile or Stare? Cadence and Sky Monitoring Observing Strategies that
  Maximize the Number of Discovered Transients

abstract:
  To maximize the number of transients discovered on the sky, should
sky-monitoring projects stare at one location or continually jump from location
to location, tiling the sky? If tiling is preferred, what cadence maximizes the
discovery rate? As sky monitoring is a growing part of astronomical observing,
utilized to find such phenomena as supernovae, microlensing, and planet
transits, well thought out answers to these questions are increasingly
important. Answers are sky, source, and telescope dependent and should include
information about the source luminosity distribution near the observation
limit, the duration of variability, the nature of the dominant noise, and the
magnitude of down and slew times. Usually, a critical slope of the effective
cumulative transient apparent luminosity distribution (Log N - Log S) at the
limiting magnitude will define when "tile" or "stare" is superior. For
shallower slopes, when "tile" is superior, optimal cadences and pointing
algorithms are discussed. For transients discovered on a single exposure or
time-contiguous series of exposures, when down and slew times are small and the
character of the noise is unchanged, the most productive cadence for isotropic
power-law luminosity distributions is the duration of the transient -- faster
cadences waste time re-discovering known transients, while slower cadences
neglect transients occurring in other fields. A "cadence creep" strategy might
find an optimal discovery cadence experimentally when one is not uniquely
predetermined theoretically. Guest investigator programs might diversify
previously dedicated sky monitoring telescopes by implementing bandpasses and
cadences chosen to optimize the discovery of different types of transients.
Example analyses are given for SuperMACHO, LSST, and GLAST.


title:
High Redshift X-Ray Selected Quasars: CXOCY J125304.0-090737 joins the
  club

abstract:
  We present a new X-ray selected high redshift quasar CXOCY J125304.0-090737
at z=4.179, discovered by the Calan-Yale Deep Extragalactic Research (CYDER)
Survey. This quasar is the fifth X-ray selected high redshift radio quiet
quasar ($z>4$) found so far. Here, we present its observed properties which are
characterized by its relative optical and X-ray faintness, its X-ray hardness
and its X-ray strength compared to optically selected quasars at high redshift.
We also compare the X-ray selected high redshift radio quiet quasars to their
optically selected counterparts. We find that the optical to X-ray spectral
slope, $\alpha_{ox}$, is statistically harder (more X-ray luminous) for the
X-ray selected radio quiet quasars than for the optically selected ones. This
result, given the different range of rest frame ultraviolet luminosities
studied and the selection of the samples, is consistent with the previously
found correlation between X-ray and rest frame ultraviolet luminosities and
would extend that result to a much wider luminosity range at high redshift.
Finally, we discuss the prospects of unveiling the quasar luminosity function
at high redshifts using X-ray surveys. The discovery of a high redshift object
in the first field of our survey program provides suggestive evidence that
X-ray selected surveys may identify more such objects than would be expected
from an extrapolation of the optical luminosity function.


title:
The dwarf Low Surface Brightness galaxy population of the Virgo Cluster
  I. The faint-end-slope of the Luminosity Function

abstract:
  The widely varying dwarf galaxy counts in different environments provide a
strong challenge to standard hierarchical clustering models. The luminosity
function is not universal, but seems to be strongly dependent upon environment.
In this paper we describe an automated procedure for detecting and measuring
very low surface brightness (LSB) features in deep CCD data. We apply this
procedure to large area CCD survey fields of the Virgo cluster. We show that
there are many more faint ($-10 \geq M_{B} \geq -14$) low surface brightness
galaxies than what would be predicted from extrapolation of the Virgo cluster
catalogue luminosity function. Over our limited range of measurement the faint
end slope of the luminosity function becomes $\alpha=- 1.6$. The luminosity
function is flatter in the inner regions of the cluster than it is in the outer
regions. Although these galaxies contribute a small fraction of the total
stellar light of the cluster, they may contribute significantly to the mass in
galaxies if they have large mass-to-light ratios similar to those recently
measured for Local Group dwarf galaxies.