title: M-BH - sigma relation for a Complete Sample of Soft X-ray Selected AGNs

abstract:
  We present black hole mass--bulge velocity dispersion relation for a complete
sample of 75 soft X-ray selected AGNs: 43 broad line Seyfert 1s and 32 narrow
line Seyfert 1s. We use luminosity and FWHM(H-beta) as surrogates for black
hole mass and FWHM([OIII]) as a surrogate for the bulge velocity dispersion. We
find that NLS1s lie below the M-BH - sigma relation of BLS1s, confirming the
Mathur et al. (2001) result. The statistical result is robust and not due to
any systematic measurement error. This has important consequences towards our
understanding of black hole formation and growth: black holes grow by accretion
in well formed bulges, possibly after a major merger. As they grow, they get
closer to the M-BH - sigma relation for normal galaxies. The accretion is
highest in the beginning and dwindles as the time goes by. Our result does not
support theories of M-BH - sigma relation in which the black hole mass is a
constant fraction of the bulge mass/ velocity dispersion at all times or those
in which bulge growth is controlled by AGN feedback.


title:
Supersoft and Quasisoft X-Ray Sources in the Globular Clusters of NGC
  4472: Are they candidates for intermediate-mass black holes?

abstract:
  We report on possible associations between 6 globular clusters in the Virgo
elliptical galaxy NGC 4472 (M49) and bright ($L_x > 10^{38}$ erg s$^{-1}$) very
soft X-ray sources (VSSs). Two of the VSSs have broad-band spectral properties
consistent with those of luminous supersoft X-ray sources (SSSs). The other
VSSs are somewhat harder harder, possibly with values of kT between roughly 150
eV and 250 eV. These sources may be too hot to be explained by the white dwarf
models so promising for SSSs; they are members of the newly-established class
of quasisoft sources (QSSs). We examine white dwarf, neutron star, and black
hole models for the VSSs. One of the SSSs is hot and bright enough to be a
possible progenitor of a Type Ia supernova, while the most natural model for
the other VSSs is one in which the accretors are intermediate-mass black holes.
Whatever their physical natures, these sources are unlike any X-ray sources in
Galactic globular clusters. No Galactic globular cluster houses a quasisoft
source and only one, M3, contains a dim ($L_x \sim 10^{36}$ erg s$^{-1}$)
transient SSS.


title: Possible Optical/Infrared Jet Emission in 4U 1543-47

abstract:
  We have taken optical and infrared observations during the 2002 outburst of
the soft X-ray transient, 4U 1543-47. A secondary maximum occurs in the
lightcurves during the outburst decline. This feature is much stronger at
infrared wavelengths than optical. We have applied single blackbody, multicolor
blackbody and broken-power law models to the optical/infrared spectral energy
distribution of the secondary maximum and find that the broken power-law
provides the best fit. We therefore conclude that the secondary maximum
emission originates from a jet. We also show the most recent lightcurves of the
2002/2003 outburst of GX 339-4 in which a secondary maximum appears. This leads
us to the conclusion that secondary maxima may be a common occurrence in soft
X-ray transients during outburst decline which appear after the object
transitions into the low-hard state. Infrared observations of such phenomena
will give reliable triggers for multiwavelength observations, allowing us to
greatly improve our knowledge of jet formation and behavior, and how this
relates to the accretion geometry.


title: The Lack of Very Ultraluminous X-ray Sources in Early-type Galaxies

abstract:
  We have searched for ultraluminous X-ray sources (ULXs) in a sample of 28
elliptical and S0 galaxies observed with Chandra. We find that the number of
X-ray sources detected at a flux level that would correspond to a 0.3-10 keV
X-ray luminosity of ~2 x 10^39 ergs/s or greater (for which we have used the
designation very ultraluminous X-ray sources; VULXs) at the distance of each
galaxy is equal to the number of expected foreground/background objects. In
addition, the VULXs are uniformly distributed over the Chandra field of view
rather than distributed like the optical light of the galaxies, strengthening
the argument that the high flux sources are unassociated with the galaxies. We
have also taken the VULX candidate list of Colbert and Ptak and determined the
spatial distribution of VULXs in early-type galaxies and late-type galaxies
separately. While the spiral galaxy VULXs are clearly concentrated toward the
centers of the galaxies, the early-type galaxy VULXs are distributed randomly
over the ROSAT HRI field of view, again indicating that they are not associated
with the galaxies themselves. We conclude that with the exception of two rare
high luminosity objects within globular clusters of the elliptical galaxy
NGC1399, VULXs are generally not found within old stellar systems. However, we
do find a significant population of sources with luminosities of 1-2 x 10^39
ergs/s that reside within the sample galaxies that can be explained by
accretion onto 10-20 solar mass black holes. Given our results, we propose that
ULXs be defined as X-ray sources with L_X(0.3-10 keV) > 2 x 10^39 ergs/s.


title:
Measuring the Mach number of the Universe via the Sunyaev-Zeldovich
  effect

abstract:
  We introduce a new statistic to measure more accurately the cosmic sound
speed of clusters of galaxies at different redshifts. This statistic is
evaluated by cross-correlating cosmic microwave background (CMB) fluctuations
caused by the Sunyaev-Zel'dovich effect from observed clusters of galaxies with
their redshifts. When clusters are distributed in redshift bins of narrow
width, one could measure the mean squared cluster peculiar velocity with an
error \sigma_{C_S^2}\lsim (300{\rm km/s})^2. This can be done around z>0.3 with
clusters of flux above 200 mJy which will be detected by PLANCK, coupled with
high resolution microwave images to eliminate the cosmological part of the CMB
fluctuations. The latter can be achieved with observations by the planned ALMA
array or the NSF South Pole telescope and other surveys. By measuring the
cosmic sound speed and the bulk flow in, e.g., 4 spheres of ~ 100h^{-1}Mpc at
z=0.3, we could have a direct measurement of the matter density
0.21<\Omega_m<0.47 at 95 % confidence level.


title: Joint Galaxy-Lensing Observables and the Dark Energy

abstract:
  Deep multi-color galaxy surveys with photometric redshifts will provide a
large number of two-point correlation observables: galaxy-galaxy angular
correlations, galaxy-shear cross correlations, and shear-shear correlations
between all redshifts. These observables can potentially enable a joint
determination of the dark energy dependent evolution of the dark matter and
distances as well as the relationship between galaxies and dark matter halos.
With recent CMB determinations of the initial power spectrum, a measurement of
the mass clustering at even a_single_ redshift will constrain a well-specified
combination of dark energy parameters in a flat universe; we provide convenient
fitting formulae for such studies. The combination of galaxy-shear and
galaxy-galaxy correlations can determine this amplitude at_multiple_ redshifts.
We illustrate this ability in a description of the galaxy clustering with 5
free functions of redshift which can be fitted from the data. The galaxy
modeling is based on a mapping onto halos of the same abundance that models a
flux-limited selection. In this context, a 4000 deg2 galaxy-lensing survey can
achieve a_statistical_ precision of sigma(Omega_DE)=0.005 for the dark energy
density, sigma(w_DE)=0.02 and sigma(w_a)=0.17 for its equation of state and
evolution, evaluated at dark energy matter equality z~0.4, as well as
constraints on the 5 halo functions out to z=1. More importantly, a joint
analysis can make dark energy constraints robust against systematic errors in
the shear-shear correlation and halo modeling.


title: Interpreting black hole QPOs

abstract:
  In all the microquasars with two hHz QPOs, the ratio of the frequencies is
3:2, supporting our suggestion that a non-linear resonance between two modes of
oscillation in the accretion disk plays a role in exciting the observed
modulations of the X-ray flux. We discuss the evidence in favor of this
interpretation, and we relate the black hole spin to the frequencies expected
for various types of resonances that may occur in nearly Keplerian disks in
strong gravity. For those microquasars where the mass of the central X-ray
source is known, the black hole spin can be deduced from a comparison of the
observed and expected frequencies.


title:
EXPLORE/OC: A Search for Planetary Transits in the Field of the Southern
  Open Cluster NGC 6208

abstract:
  The EXPLORE Project expanded in 2003 to include a campaign to monitor rich
southern open clusters for transits of extrasolar planets (EXPLORE/OC). In May
and June 2003, we acquired precise, high-cadence photometry of the second open
cluster in our campaign, NGC 6208. Here, we present preliminary results from
our I-band survey of over 60000 stars in the field of NGC 6208, around 5000 of
which were monitored with photometric precision better than 1%.


title:
Structural and scaling properties of galaxy clusters: probing the
  physics of structure formation

abstract:
  We present XMM-Newton studies of the total mass, gas density, temperature and
entropy profiles in nearby hot and cool clusters, together with follow-up
observations of distant clusters from the SHARC Survey. The observed structural
and scaling properties are compared with the predictions of the self-similar
model of cluster formation. These data indicate that clusters do form a
self-similar population down to low mass and up to high redshift, and give
support to the standard picture of structure formation for the dark matter
component. However, deviations from the standard scaling laws confirm that the
specific physics of the gas component is still insufficiently understood.


title: Long and short gamma-ray bursts, and the pulsar kicks

abstract:
  One of the mysteries that surround gamma-ray bursts (GRB) is the origin of
two classes of events: long and short GRB. The short GRB are similar to the
first second of a long GRB. We suggest that the short bursts are interrupted
long bursts, we point out a plausible mechanism for the interruption, and we
explain the observed time scales. The supernova-like central engine may contain
a neutron star or a black hole surrounded by an accretion disk and jets. In the
case of a neutron star, the same mechanism that is responsible for the pulsar
kicks can disrupt the central engine, thus producing an interrupted, short GRB.
If a black hole is produced, the absence of the kick ensures the long duration
of the GRB. The time delay of the kick and the absence of the kick for a black
hole are natural consequences of a model based on neutrino oscillations.


title: Searching for GRB remnants in nearby galaxies

abstract:
  Gamma Ray Bursts (GRBs) are expected to leave behind GRB remnants, similar to
how ``standard'' supernovae (SN) leave behind SN remnants. The identification
of these remnants in our own and in nearby galaxies would allow a much closer
look at GRB birth sites, and possibly lead to the discovery of the compact
object left behind. It would also provide independent constraints on GRB rates
and energetics. We have initiated an observational program to search for GRB
remnants in nearby galaxies. The identification is based on specific line
ratios, such as OIII/$H_{\beta}$ and HeII/$H_{\beta}$, which are expected to be
unusually high in case of GRB remnants according to the theoretical predictions
of Perna et al. (2000). The observing strategies and preliminary studies from a
test run at 2.34 m VBT as well as archival data from planetary nebulae surveys
of spiral galaxies are discussed.


title:
No evidence for a different accretion mode for all 3CR FR I radio
  galaxies

abstract:
  We have analyzed the optical and radio properties of a sample of 3CR FR I
radio galaxies which have Hubble Space Telescope imaging capable of detecting
optical cores. The jet powers of the FR I radio galaxies are estimated from
their low-frequency radio luminosities, and the optical core luminosity is
taken as an upper limit on the emission from any unobscured accretion disc. We
argue that if the accretion discs in these sources are assumed to be advection
dominated accretion flows (ADAFs), or adiabatic inflow-outflow solution (ADIOS)
flows, then the Blandford-Znajek mechanism (Blandford & Znajek 1977) provides
insufficient power to explain the high radio luminosities of at least a third,
and perhaps all, of the sample. We suggest instead that a significant fraction
(the 'high-jet-power' third), and perhaps most, of the 3CR FR I radio galaxies
have normal accretion discs, but that their optical cores can be hidden, with
any HST-detected optical synchrotron emission coming from jets on scales larger
than the obscuring material. A normal accretion disc hypothesis, at least for
the high-jet-power third of the 3CR FR Is, explains why narrow-line luminosity
correlates with radio luminosity. It also explains why one object in the sample
(3C 386) has an observed broad-line nucleus. We conclude that there is no
evidence to suggest that there is a difference in accretion mode between FR I
and FR II radio galaxies.


title: Extreme gas properties in the most distant quasars

abstract:
  We present near-IR, low resolution spectra of eight of the most distant
quasars known, with redshifts in the range 4.9<z<6.4. Half of these quasars are
characterized by deep, broad and blueshifted absorption features associated
with both high and low ionization species (CIV, SiIV, AlIII, MgII), i.e. they
belong to the class of Broad Absorption Line (BAL) quasars, which are
associated with powerful outflows of dense gas. Although the sample is small,
the large fraction of BAL quasars, the depth and ionization state of the
absorption features suggest that these most distant quasars are surrounded by a
much larger amount of dense gas than lower redshift (z<4) quasars. The possible
interpretation in terms of extremely high accretion rates and the association
with the early formation of quasars and of their host galaxies is discussed.
The absorption properties of the dust, associated with the gas along the line
of sight, appear different with respect to lower redshift quasars, possibly
indicating different dust physics at these highest redshifts.


title:
On the close optical companion of V1494 Aql: problems with light curve
  modelling

abstract:
  New observations of the eclipsing nova V1494 Aql were analysed in order to
estimate the effect of the optical companion located 1.4 arcsec southwest. R
and I-band images (stellar FWHM~1.2-1.4 arcsec) taken close to the primary
minimum were used to determine relative magnitude differences between the nova
and the companion, which were found to be Delta R~0.20 mag and Delta I~0.52 mag
(in the sense nova minus companion). After correcting R-band time-series
observations for the secondary light, the eclipse depth has been found to be
almost twice as deep. Before modelling any late eclipsing light curve that is
available in the literature, the data must be corrected for the light of the
companion.


title:
Reevaluation of the $^{22}$Na(p,$\gamma$) reaction rate: Implications
  for the detection of $^{22}$Na gamma rays from novae

abstract:
  Understanding the processes which create and destroy $^{22}$Na is important
for diagnosing classical nova outbursts. Conventional $^{22}$Na(p,$\gamma$)
studies are complicated by the need to employ radioactive targets. In contrast,
we have formed the particle-unbound states of interest through the heavy-ion
fusion reaction, $^{12}$C($^{12}$C,n)$^{23}$Mg and used the Gammasphere array
to investigate their radiative decay branches. Detailed spectroscopy was
possible and the $^{22}$Na(p,$\gamma$) reaction rate has been re-evaluated. New
hydrodynamical calculations incorporating the upper and lower limits on the new
rate suggest a reduction in the yield of $^{22}$Na with respect to previous
estimates, implying a reduction in the maximum detectability distance for
$^{22}$Na $\gamma$ rays from novae.


title:
Are Coronae of Magnetically Active Stars Heated by Flares? III.
  Analytical Distribution of Superimposed Flares

abstract:
  (abridged) We study the hypothesis that observed X-ray/extreme ultraviolet
emission from coronae of magnetically active stars is entirely (or to a large
part) due to the superposition of flares, using an analytic approach to
determine the amplitude distribution of flares in light curves. The
flare-heating hypothesis is motivated by time series that show continuous
variability suggesting the presence of a large number of superimposed flares
with similar rise and decay time scales. We rigorously relate the amplitude
distribution of stellar flares to the observed histograms of binned counts and
photon waiting times, under the assumption that the flares occur at random and
have similar shapes. Applying these results to EUVE/DS observations of the
flaring star AD Leo, we find that the flare amplitude distribution can be
represented by a truncated power law with a power law index of 2.3 +/- 0.1. Our
analytical results agree with existing Monte Carlo results of Kashyap et al.
(2002) and Guedel et al. (2003). The method is applicable to a wide range of
further stochastically bursting astrophysical sources such as cataclysmic
variables, Gamma Ray Burst substructures, X-ray binaries, and spatially
resolved observations of solar flares.


title: A Hot Spot Model for Black Hole QPOs

abstract:
  In at least two black hole binary systems, the Rossi X-Ray Timing Explorer
has detected high frequency quasi-periodic oscillations (HFQPOs) with a 2:3
frequency commensurability. We propose a simple hot spot model to explain the
positions, amplitudes, and widths of the HFQPO peaks. Using the exact geodesic
equations for the Kerr metric, we calculate the trajectories of massive test
particles, which are treated as isotropic, monochromatic emitters in their rest
frames. By varying the hot spot parameters, we are able to explain the
different features observed in ``Type A'' and ``Type B'' QPOs from XTE
J1550-564. In the context of this model, the observed power spectra allow us to
infer values for the black hole mass and angular momentum, and also constrain
the parameters of the model.


title:
Can long-term periodic variability and jet helicity in 3C 120 be
  explained by jet precession?

abstract:
  Optical variability of 3C 120 is discussed in the framework of jet
precession. Specifically, we assume that the observed long-term periodic
variability is produced by the emission from an underlying jet with a
time-dependent boosting factor driven by precession. The differences in the
apparent velocities of the different superluminal components in the
milliarcsecond jet can also be explained by the precession model as being
related to changes in the viewing angle. The evolution of the jet components
has been used to determine the parameters of the precession model, which also
reproduce the helical structure seen at large scales. Among the possible
mechanisms that could produce jet precession, we consider that 3C 120 harbours
a super-massive black hole binary system in its nuclear region and that torques
induced by misalignment between the accretion disc and the orbital plane of the
secondary black hole are responsible for this precession; we estimated upper
and lower limits for the black holes masses and their mean separation.


title: Excess mid-IR emission in Cataclysmic Variables

abstract:
  We present a search for excess mid-IR emission due to circumbinary material
in the orbital plane of cataclysmic variables (CVs). Our motivation stems from
the fact that the strong braking exerted by a circumbinary (CB) disc on the
binary system could explain several puzzles in our current understanding of CV
evolution. Since theoretical estimates predict that the emission from a CB disc
can dominate the spectral energy distribution (SED) of the system at
wavelengths > 5 microns, we obtained simultaneous visible to mid-IR SEDs for
eight systems. We report detections of SS Cyg at 11.7 microns and AE Aqr at
17.6 microns, both in excess of the contribution from the secondary star. In AE
Aqr, the IR likely originates from synchrotron-emitting clouds propelled by the
white dwarf. In SS Cyg, we argue that the observed mid-IR variability is
difficult to reconcile with simple models of CB discs and we consider free-free
emission from a wind. In the other systems, our mid-IR upper limits place
strong constraints on the maximum temperature of a putative CB disc. The
results show that if any sizeable CB disc are present in these systems, they
must be self-shadowed or perhaps dust-free, with the peak thermal emission
shifted to far-IR wavelengths.


title:
Are interactions the primary triggers of star formation in dwarf
  galaxies?

abstract:
  We investigate the assumption that the trigger of star formation in dwarf
galaxies are interactions with other galaxies, in the context of a search for a
"primary" trigger of a first generation of stars. This is cosmologically
relevant because the galaxy formation process consists not only of the
accumulation of gas in a gravitational potential well, but also of the
triggering of star formation in this gas mass and also because some high-z
potentially primeval galaxy blocks look like nearby star-forming dwarf
galaxies. We review theoretical ideas proposed to account for the tidal
interaction triggering mechanism and present a series of observational tests of
this assumption using published data. We show also results of a search in the
vicinity of a composite sample of 96 dwarf late-type galaxies for interaction
candidates showing star formation. The small number of possible perturbing
galaxies indentified in the neighborhood of our sample galaxies, along with
similar findings from other studies, supports the view that tidal interactions
may not be relevant as primary triggers of star formation. We conclude that
interactions between galaxies may explain some forms of star formation
triggering, perhaps in central regions of large galaxies, but they do not seem
to be significant for dwarf galaxies and, by inference, for first-time galaxies
forming at high redshifts. Intuitive reasoning, based on an analogy with
stellar dynamics, shows that conditions for primary star formation triggering
may occur in gas masses oscillating in a dark matter potential. We propose this
mechanism as a plausible primary trigger scenario, worth investigating
theoretically.


title:
Indications of a Large Fraction of Spectroscopic Binaries Among Nuclei
  of Planetary Nebulae

abstract:
  Previous work indicates that about 10% of planetary-nebula nuclei (PNNi) are
photometrically variable short-period binaries with periods of hours to a few
days. These systems have most likely descended from common-envelope (CE)
interactions in initially much wider binaries. Population-synthesis studies
suggest that these very close pairs could be the short-period tail of a much
larger post-CE binary population with periods of up to a few months. We have
initiated a radial-velocity (RV) survey of PNNi with the WIYN 3.5-m telescope
and Hydra spectrograph, which is aimed at discovering these intermediate-period
binaries. We present initial results showing that 10 out of 11 well-observed
PNNi have variable RVs, suggesting that a significant binary population may be
present. However, further observations are required because we have as yet been
unable to fit our sparse measurements with definite orbital periods, and
because some of the RV variability might be due to variations in the stellar
winds of some of our PNNi.


title:
Dynamical properties of a family of collisionless models of elliptical
  galaxies

abstract:
  N-body simulations of collisionless collapse have offered important clues to
the construction of realistic stellar dynamical models of elliptical galaxies.
Such simulations confirm and quantify the qualitative expectation that rapid
collapse of a self-gravitating collisionless system, initially cool and
significantly far from equilibrium, leads to incomplete relaxation, that is to
a quasi-equilibrium configuration characterized by isotropic, quasi-Maxwellian
distribution of stellar orbits in the inner regions and by radially biased
anisotropic pressure in the outer parts. In earlier studies, as illustrated in
a number of papers several years ago (see Bertin et al. 1993 and references
therein), the attention was largely focused on the successful comparison
between the models (constructed under the qualitative clues offered by the
N-body simulations mentioned above) and the observations. In this paper we
revisit the problem of incomplete violent relaxation, by making a direct
comparison between the detailed properties of a family of distribution
functions and those of the products of collisionless collapse found in N-body
simulations.


title: CIV Absorbers in z>4 Quasars: Tracing Early Galactic Halos Evolution

abstract:
  We use 29 z>4 quasar spectra to build a homogeneous sample of high-redshift
CIV absorbers. We use these data to calculate the number density, n(z), of
W_rest(CIV)>0.30 A CIV doublets. We find that n(z) increases with time from z ~
4.5. In addition, W_rest(CIV)>0.15 A CIV systems are more numerous than the
former at all redshifts. On the contrary, n(z) of W_rest(MgII)>0.30 A MgII
doublets decreases with time, in agreement with results from studies of LLS
number densities. Below z<3, none of all the classes of absorbers show signs of
evolution. We interpret this as the formation of galactic envelopes from
smaller halos. Furthermore, the doublet ratio DR=W(CIV 1548)/W(CIV 1550) is
found to decrease with time, a signature of the increase of the mean CIV column
density. Finally, the W(SiIV 1393)/W(CIV 1548) ratios in strong absorbers
(W_rest(CIV 1548) > 0.50 A) is found to be approximately constant from z=3.5 to
z=2.5 and then to decrease with time. This result suggests that the highest
column density absorbers are not sensitive to changes in the ionization
continuum.


title:
A phase-dependent absorption line in the spectrum of the X-ray pulsar RX
  J0720.4-3125

abstract:
  The XMM-Newton spectra of the isolated neutron star RX J0720.4-3125 show
deviations from a Planckian energy distribution below 400 eV, similar to the
spectra of RBS1223, another long-period X-ray pulsar, as reported recently by
Haberl et al. (2003). For a Gaussian-shaped absorption line we derive an energy
of 271 eV and an equivalent width of -40 eV from the phase-averaged spectra of
RX J0720.4-3125. We investigate the spectral variations seen in hardness ratios
as function of pulse phase and find that they are best described by changes in
the depth of the absorption line. The line equivalent width changes between -31
eV around intensity maximum of the pulse and -58 eV at the declining part of
the pulse. Small variations (<20 eV) of the line energy with pulse phase may
still be caused by statistical fluctuations. On the other hand, the black-body
temperature varies significantly by 2.5 eV (statistical 90% errors typically
0.7 eV) reaching the highest value at pulse maximum. One possible
interpretation for the absorption line is cyclotron resonance scattering of
protons in a magnetic field with B about 5x10^13 G. This field strength is
compatible with estimates inferred from recent spin down measurements of the
pulsar.


title:
Covariant analysis of Newtonian multi-fluid models for neutron stars: II
  Stress - energy tensors and virial theorems

abstract:
  The 4-dimensionally covariant approach to multiconstituent Newtonian fluid
dynamics presented in the preceding article of this series is developed by
construction of the relevant 4-dimensional stress energy tensor whose
conservation in the non-dissipative variational case is shown to be
interpretable as a Noether identity of the Milne spacetime structure. The
formalism is illustrated by the application to homogeneously expanding
cosmological models, for which appropriately generalised local Bernouilli
constants are constructed. Another application is to the Iordanski type
generalisation of the Joukowski formula for the Magnus force on a vortex.
Finally, at a global level, a new (formally simpler but more generally
applicable) version of the ``virial theorem'' is obtained for multiconsituent
-- neutron or other -- fluid star models as a special case within an extensive
category of formulae whereby the time evolution of variously weighted mass
moment integrals is determined by corresponding space integrals of stress
tensor components, with the implication that all such stress integrals must
vanish for any stationary equilibrium configuration.


title: What is the Broad Line Region?

abstract:
  What is the Broad Line Region (BLR) made of? What determines its location?
Why is it sometimes missing? What controls its properties? Some recent results
and new approaches which may shed light on these issues are briefly described.


title: Constraining the reionization history with large angle CMB polarization

abstract:
  The first-year WMAP data release showed that the reionization optical depth
to CMB photons is greater than previously thought. This follows from
unexpectedly high values of the C^TE_l spectrum, for l up to ~30, presumably
allowing a measurement of the E-mode polarization spectrum C^E_l sooner than
expected. This note aims to test the capability of large-angle polarization
experiments to explore the history of the cosmological reionization,
considering also the impact of cosmic variance. In particular, here we discuss
how well the ionized fraction x_e and the reionization redshift z_r can be
separately measured, at various levels of instrumental noise.


title: Some Comments related to AGN Radio Loudness

abstract:
  The bimodality of the AGN radio loudness distribution, and the relation of
radio loudness and black hole mass were recently disputed. A closer look at the
existing data suggests possible resolutions of these disputes, as further
described below.


title: XMM-Newton spectroscopy of high redshift quasars

abstract:
  We present XMM-Newton X-ray spectra and optical photometry of four high
redshift (z=2.96-3.77) quasars, [HB89] 0438-436, [HB89] 2000-330, [SP89]
1107+487 and RX J122135.6+280613; of these four objects the former two are
radio-loud, the latter two radio-quiet. Model fits require only a power law
with Galactic absorption in each case; additional intrinsic absorption is also
needed for [HB89] 0438-436 and RX J122135.6+280613. The spectra are hard (Gamma
\~1.7 for [HB89] 0438-436, [HB89] 2000-330 and ~1.4 for RX J122135.6+280613)
with the exception of [SP89]~1107+487 which is softer (Gamma ~2.0); the
combined Galactic and intrinsic absorption of lower energy X-rays in the latter
source is much less significant than in the other three. The two intrinsically
unabsorbed sources have greater optical fluxes relative to the X-ray
contributions at the observed energies. While there is no need to include
reflection or iron line components in the models, our derived upper limits (99%
confidence) on these parameters are not stringent; the absence of these
features, if confirmed, may be explained in terms of the high power law
contribution and/or a potentially lower albedo due to the low disc temperature.
However, we note that the power-law spectrum can be produced via mechanisms
other than the Comptonization of accretion disc emission by a corona; given
that all four of these quasars are radio sources at some level we should also
consider the possibility that the X-ray emission originates, at least
partially, in a jet.


title:
XMM-Newton observations of two X-ray bright galaxy groups - pushing out
  to r_500

abstract:
  We report on the results of XMM-Newton observations of the z=0.18 galaxy
group WARPJ0943.7+1644 and the nearby poor cluster WARPJ0943.5+1640 at z=0.256.
Tracing the X-ray gas out to ~425h^(-1) and ~500h^(-1) kpc in the two systems,
corresponding to roughly 70 per cent of the estimated virial radii, we find the
surface brightness profile of both groups to be well described by standard
beta-models across the entire radial range, but with a significantly lower
value of beta in the cooler WARPJ0943.7+1644. A Navarro-Frenk-White (NFW) model
for the gas density can also provide a good fit to the surface brightness data,
but a large scale radius is required, and gas-traces-mass is strongly ruled
out. Both systems fall close to the observed L_X-T relation for clusters. Gas
mass fractions increase with radius out to the radii probed, reaching
extrapolated values at the virial radius of 0.08 and 0.09h^(-3/2),
respectively. The latter is concordant with results obtained for more massive
systems. Gas entropy profiles show evidence for excess entropy out to at least
r_500, and are inconsistent with predictions of simple preheating models. This
study emphasizes the need for observing galaxy groups out to large radii, to
securely establish their global properties.


title: What is the Origin of the Baldwin Effect in the BLR and the NLR?

abstract:
  The origin of the luminosity dependence of the strength of broad and narrow
emission lines in AGN (i.e. the Baldwin effect) is not firmly established yet.
We explore this question using the Boroson & Green sample of the 87 z<=0.5 PG
quasars. UV spectra of the C IV region with a sufficient S/N are available for
81 of the objects. We use these spectra to explore the dependence of the C IV
EW on M_BH and L_Edd, as deduced from optical spectra of the H beta region. We
find a strong correlation of the C IV EW with L_Edd. This may be the primary
correlation which drives the Baldwin effect for C IV. A similar correlation
analysis using the C IV FWHM instead of the H beta FWHM, yields an
insignificant correlation. This suggests that the C IV FWHM provides a
significantly less accurate estimate of M_BH compared to the H Beta FWHM. We
also measured the [O III] 4363 /[O III] 5007 line ratio for 72 objects in this
sample, and use it to determine whether density or covering factor control the
large range in [O III] 5007 strength in AGN.


title:
The origins of Causality Violations in Force Free Simulations of Black
  Hole Magnetospheres

abstract:
  Recent simulations of force-free, degenerate (ffde) black hole magnetospheres
indicate that the fast mode radiated from (or near) the event horizon can
modify the global potential difference in the poloidal direction orthogonal to
the magnetic field, V, in a black hole magnetosphere. There is a fundamental
contradiction in a wave that alters V coming from near the horizon. The
background fields in ffde satisfy the ``ingoing wave condition'' near the
horizon (that arises from the requirement that all matter is ingoing at the
event horizon), yet outgoing waves are radiated from this region in the
simulation. Studying the properties of the waves in the simulations are useful
tools to this end. It is shown that regularity of the stress-energy tensor in a
freely falling frame requires that the outgoing (as viewed globally) waves near
the event horizon are redshifted away and are ineffectual at changing V. It is
also concluded that waves in massless MHD (ffde) are extremely inaccurate
depictions of waves in a tenuous MHD plasma, near the event horizon, as a
consequence black hole gravity. Any analysis based on ffde near the event
horizon is seriously flawed.


title: X-ray/Optical Variability of Akn 120 and 3C 120

abstract:
  Using the Rossi X-ray Timing Experiment (RXTE), we have observed both the
Seyfert 1 galaxy Akn 120 and the broad-line radio galaxy 3C 120. Monitoring
observations spanning 2 years plus intensive stares spanning several days have
been obtained for both objects. These data have allowed us to construct the
power density spectrum (PDS) for each object. Covering more than 4 decades in
temporal frequency, the PDS for 3C 120 represents the first such measurement
for a radio loud galaxy. The PDS for 3C 120 shows a steep power law at high
frequencies, which turns over at low frequencies. Akn 120 also has a power law
shape in its PDS. Using the PDS of Cygnus X-1, we estimate the masses for both
of these objects. Optical data and cross correlation functions are also
presented for Akn 120. The long-term light curve of Akn 120 shows a strong
correlation with optical data, with zero time lag.


title:
Similarities in the temporal properties of gamma-ray bursts and soft
  gamma-ray repeaters

abstract:
  Magnetars are modelled as sources that derive their output from magnetic
energy that substantially exceeds their rotational energy. An implication of
the recent polarization measurement of GRB 021206 is that the emission
mechanism may be dominated by a magnetic field that originates in the central
engine. Similarities in the temporal properties of SGRs and GRBs are considered
in light of the fact that the central engine in GRBs may be magnetically
dominated. The results show that 1) the time intervals between outbursts in SRG
1806-20 and pulses in GRBs are consistent with lognormal distributions and 2)
the cumulative outputs of SGRs and GRBs increase linearly with time. This
behaviour can be successfully modelled by a relaxation system that maintains a
steady state situation.


title: Testing dark energy beyond the cosmological constant barrier

abstract:
  Although well motivated from theoretical arguments, the cosmological constant
\emph{barrier}, i.e., the imposition that the equation-of-state parameter of
dark energy ($\omega_x \equiv p_x/\rho_x$) is $\geq -1$, seems to introduce
bias in the parameter determination from statistical analyses of observational
data. In this regard, \emph{phantom} dark energy or \emph{superquintessence}
has been proposed in which the usual imposition $\omega \geq -1$ is relaxed.
Here, we study possible observational limits to the \emph{phantom} behavior of
the dark energy from recent distance estimates of galaxy clusters obtained from
interferometric measurements of the Sunyaev-Zel'dovich effect/X-ray
observations, Type Ia supernova data and CMB measurements. We find that there
is much \emph{observationally} acceptable parameter space beyond the $\Lambda$
\emph{barrier}, thus opening the possibility of existence of more exotic forms
of energy in the Universe.


title:
Review of Spectroscopic Determination of Extra Spatial Dimensions in the
  Early Universe

abstract:
  Atomic and molecular transitions for high Z objects in the early universe
give bounds to the possible existence of extra spatial dimensions $D =
3+\epsilon$. We review the theory and present observational data, based on
Lyman and Balmer hydrogen transitions of distant quasars and CO rotational
transitions of far away giant molecular clouds.


title:
Constraints on the Formation of PSR J0737-3039: the most probable
  isotropic kick magnitude

abstract:
  A strongly relativistic binary pulsar has been recently discovered with the
64m Parkes telescope (Burgay et al. 2003). Here we use the measured properties
of this binary (masses and orbital characteristics as well as age estimates),
and we derive the complete set of constraints imposed on the physical
properties of the binary pulsar progenitor right before the second supernova
explosion. We find that: (i) according to our current understanding of
neutron-star formation, the helium-rich progenitor of the second neutron star
is most likely overflowing its Roche lobe; (ii) the neutron-star kick magnitude
is constrained in the range 60-1560 km/s, with the most probable value being
equal to 150 km/s. While the first conclusion is in agreement with Dewi & van
den Heuvel (2003), our upper limit on the kick magnitude is significantly
larger than that derived by these authors. We find that the difference arises
because Dewi & van den Heuvel (2003) inadvertently neglected to consider kicks
directed out of the pre-supernova orbital plane.


title:
A Gravitationally Lensed Quasar with Quadruple Images Separated by 14.62
  Arcseconds

abstract:
  Gravitational lensing is a powerful tool for the study of the distribution of
dark matter in the Universe. The cold-dark-matter model of the formation of
large-scale structures predicts the existence of quasars gravitationally lensed
by concentrations of dark matter so massive that the quasar images would be
split by over 7 arcsec. Numerous searches for large-separation lensed quasars
have, however, been unsuccessful. All of the roughly 70 lensed quasars known,
including the first lensed quasar discovered, have smaller separations that can
be explained in terms of galaxy-scale concentrations of baryonic matter.
Although gravitationally lensed galaxies with large separations are known,
quasars are more useful cosmological probes because of the simplicity of the
resulting lens systems. Here we report the discovery of a lensed quasar, SDSS
J1004+4112, which has a maximum separation between the components of 14.62
arcsec. Such a large separation means that the lensing object must be dominated
by dark matter. Our results are fully consistent with theoretical expectations
based on the cold-dark-matter model.


title:
The History of the Mysterious Eclipses of KH 15D: Asiago Observatory,
  1967-1982

abstract:
  We are gathering archival observations to determine the photometric history
of the unique and unexplained eclipses of the pre-main-sequence star KH 15D.
Here we present a light curve from 1967-1982, based on photographic plates from
Asiago Observatory. During this time, the system alternated periodically
between bright and faint states, as observed today. However, the bright state
was 0.9 mag brighter than the modern value, and the fractional variation
between bright and faint states (Delta I = 0.7 mag) was smaller than observed
today (3.5 mag). A possible explanation for these findings is that the system
contains a second star that was previously blended with the eclipsing star, but
is now completely obscured.


title:
Observations and Theoretical Implications of the Large Separation Lensed
  Quasar SDSS J1004+4112

abstract:
  We study the recently discovered gravitational lens SDSS J1004+4112, the
first quasar lensed by a cluster of galaxies. It consists of four images with a
maximum separation of 14.62''. The system has been confirmed as a lensed quasar
at z=1.734 on the basis of deep imaging and spectroscopic follow-up
observations. We present color-magnitude relations for galaxies near the lens
plus spectroscopy of three central cluster members, which unambiguously confirm
that a cluster at z=0.68 is responsible for the large image separation. We find
a wide range of lens models consistent with the data, but they suggest four
general conclusions: (1) the brightest cluster galaxy and the center of the
cluster potential well appear to be offset by several kpc; (2) the cluster mass
distribution must be elongated in the North--South direction, which is
consistent with the observed distribution of cluster galaxies; (3) the
inference of a large tidal shear (~0.2) suggests significant substructure in
the cluster; and (4) enormous uncertainty in the predicted time delays between
the images means that measuring the delays would greatly improve constraints on
the models. We also compute the probability of such large separation lensing in
the SDSS quasar sample, on the basis of the CDM model. The lack of large
separation lenses in previous surveys and the discovery of one in SDSS together
imply a mass fluctuation normalization \sigma_8=1.0^{+0.4}_{-0.2} (95% CL), if
cluster dark matter halos have an inner slope -1.5. Shallower profiles would
require higher values of \sigma_8. Although the statistical conclusion might be
somewhat dependent on the degree of the complexity of the lens potential, the
discovery is consistent with the predictions of the abundance of cluster-scale
halos in the CDM scenario. (Abridged)


title: Testing for a Super-Acceleration Phase of the Universe

abstract:
  We propose a method to probe the phenomenological nature of dark energy which
makes no assumptions about the evolution of its energy density. We exemplify
this method with a test for a super-acceleration phase of the universe i.e., a
phase when the dark energy density grows as the universe expands. We show how
such a phase can be detected by combining SNIa (SNAP-like) and CMB (Planck)
data without making any assumptions about the evolution of the dark energy
equation of state, or about the value of the matter density parameter.


title:
Forming Young Bulges within Existing Disks: Statistical Evidence for
  External Drivers

abstract:
  Contrary to traditional models of galaxy formation, recent observations
suggest that some bulges form within preexisting disk galaxies. Such late-epoch
bulge formation within disks seems to be linked to disk gas inflow and central
star formation, caused by either internal secular processes or galaxy mergers
and interactions. We identify a population of galaxies likely to be
experiencing active bulge growth within disks, using the criterion that the
color within the half-light radius is bluer than the outer disk color. Such
blue-centered galaxies make up >10% of star-forming disk galaxies within the
Nearby Field Galaxy Survey, a broad survey designed to represent the natural
diversity of the low-z galaxy population over a wide range of luminosities and
environments. Blue-centered galaxies correlate at 99% confidence with
morphological peculiarities suggestive of minor mergers and interactions. From
this and other evidence, we argue that external drivers rather than internal
secular processes probably account for the majority of blue-centered galaxies.
We go on to discuss quantitative plausibility arguments indicating that
blue-centered evolutionary phases may represent an important mode of bulge
growth for most disk galaxies, leading to significant changes in bulge-to-disk
ratio without destroying disks. If this view is correct, bulge growth within
disks may be a natural consequence of the repeated galaxy mergers and
interactions inherent in hierarchical galaxy formation.


title:
Sherlock: An Automated Follow-Up Telescope for Wide-Field Transit
  Searches

abstract:
  The most significant challenge currently facing photometric surveys for
transiting gas-giant planets is that of confusion with eclipsing binary systems
that mimic the photometric signature. A simple way to reject most forms of
these false positives is high-precision, rapid-cadence monitoring of the
suspected transit at higher angular resolution and in several filters. We are
currently building a system that will perform higher-angular-resolution,
multi-color follow-up observations of candidate systems identified by Sleuth
(our wide-field transit survey instrument at Palomar), and its two twin system
instruments in Tenerife and northern Arizona.


title: A Timing Signature of Gravitational Radiation from LMXB Neutron Stars

abstract:
  The coupled evolution of the spin frequency, core temperature, and r-mode
amplitude of an accreting neutron star is calculated. We focus on those
conditions that can produce persistent gravitational radiation from the r-mode.
During X-ray quiescent phases of transient LMXBs, one may be able to identify
the constant contribution of the gravitational wave emission to the spindown
rate. Another signature is the r-mode contribution to the heating.


title: Noise-Induced Phase Space Transport in Time-Periodic Hamiltonian Systems

abstract:
  Orbits in a three-dimensional potential subjected to periodic driving,
V(x^i,t)=[1+m_0 sin(omega t) V_0(x^i), divide naturally into two types, regular
and chaotic, between which transitions are seemingly impossible. The chaotic
orbits divide in turn into two types, apparently separated by entropy barriers,
namely `sticky' orbit segments, which are `locked' to the driving frequency and
exhibit little systematic energy diffusion, and `wildly' chaotic segments,
which are not so locked and can exhibit significant energy diffusion. Attention
focuses on how the relative abundance of these different orbit types and the
transition rate between sticky and wildly chaotic orbits depends on amplitude
m_0, and on the extent to which these quantities can be altered by weak
friction and/or noise and by pseudo-random variations in the driving frequency,
idealized as an Ornstein-Uhlenbeck process with (in general) nonzero
autocorrelation time t_c. When, in the absence of perturbations, there exist
large measures of both regular and chaotic orbits, the primary effect of weak
noise is to increase the relative measure of chaotic orbits. Alternatively,
when almost all the orbits are already chaotic, noise serves primarily to
accelerate transitions from sticky to wildly chaotic behavior. The presence or
absence of friction is unimportant and the details of the noise seem largely
immaterial. In particular, there is only a weak, roughly logarithmic dependence
on amplitude, and additive and multiplicative noise typically have virtually
identical effects. By contrast, allowing for high frequency `noisy' variations
in omega tends to weaken effects of the driving, decreasing the relative
measure of chaotic orbits and suppressing large scale energy diffusion.


title: Large-Scale Structure Shocks at Low and High Redshifts

abstract:
  Cosmological simulations show that, at the present time, a substantial
fraction of the gas in the intergalactic medium (IGM) has been shock-heated to
T>10^5 K. Here we develop an analytic model to describe the fraction of
shocked, moderately overdense gas in the IGM. The model is an extension of the
Press & Schechter (1974) description for the mass function of halos: we assume
that large-scale structure shocks occur at a fixed overdensity during nonlinear
collapse. This in turn allows us to compute the fraction of gas at a given
redshift that has been shock-heated to a specified temperature. We show that,
if strong shocks occur at turnaround, our model provides a reasonable
description of the temperature distribution seen in cosmological simulations at
z~0, although it does overestimate the importance of weak shocks. We then apply
our model to shocks at high redshifts. We show that, before reionization, the
thermal energy of the IGM is dominated by large-scale structure shocks (rather
than virialized objects). These shocks can have a variety of effects, including
stripping ~10% of the gas from dark matter minihalos, accelerating cosmic rays,
and creating a diffuse radiation background from inverse Compton and cooling
radiation. This radiation background develops before the first stars form and
could have measurable effects on molecular hydrogen formation and the spin
temperature of the 21 cm transition of neutral hydrogen. Finally, we show that
shock-heating will also be directly detectable by redshifted 21 cm measurements
of the neutral IGM in the young universe.


title: The essential signature of a massive starburst in a distant galaxy

abstract:
  Observations of carbon monoxide (CO) emission in high redshift (z>2) galaxies
indicate the presence of large amounts of molecular gas. Many of these galaxies
contain an active galactic nucleus (AGN) powered by accretion of gas onto a
supermassive black hole, and a key question is whether their extremely high
infrared luminosities result from the AGN, or from bursts of massive star
formation (associated with the molecular gas), or both. In the Milky Way,
high-mass stars form in the dense cores of interstellar molecular clouds; gas
densities are n(H2)>105 cm-3 in the cores. Recent surveys show that virtually
all galactic sites of high-mass star formation have similarly high densities.
The bulk of the cloud material traced by CO observations is at a much lower
density. In galaxies in the local Universe, the HCN(J=1-0) line is an effective
tracer of the high-density molecular gas. Here we report observations of HCN
emission in the early Universe from the infrared luminous 'Cloverleaf' quasar
(at a redshift z=2.5579). The HCN line luminosity indicates the presence of 10
billion solar masses of very dense gas, an essential feature of an immense
starburst that contributes, together with the AGN it harbors, to its high
infrared luminosity.


title:
Toward Epoch of Reionization Measurements with Wide-Field Radio
  Observations

abstract:
  This paper explores the potential for statistical epoch of reionization (EOR)
measurements using wide field radio observations. New developments in low
frequency radio instrumentation and signal processing allow very sensitive EOR
measurements, and the analysis techniques enabled by these advances offer
natural ways of separating the EOR signal from the residual foreground
emission. This paper introduces the enabling technologies and proposes an
analysis technique designed to make optimal use of the capabilities of next
generation low frequency radio arrays. The observations we propose can directly
observe the power spectrum of the EOR using relatively short observations, and
are significantly more sensitive than other techniques which have been
discussed in the literature. For example, in the absence of foreground
contamination the measurements we propose would produce five 3-sigma power
spectrum points in 100 hours of observation with only 4 MHz bandwidth with
LOFAR for simple models of the high redshift 21cm emission. The challenge of
residual foreground removal may be addressed by the symmetries in the
three-dimensional (two spatial frequencies and radiofrequency) radio
interferometric data. These symmetries naturally separate the EOR signal from
most classes of residual un-subtracted foreground contamination, including all
foreground continuum sources and radio line emission from the Milky Way.


title:
Early afterglow, magnetized central engine, and a quasi-universal jet
  configuration for long GRBs

abstract:
  Two separate topics are discussed. (1) We describe the classifications of the
long GRB early afterglow lightcurves within the framework of the fireball shock
model, focusing on the interplay between the reverse and forward shock emission
components. We will also provide evidence that the central engine of at least
two bursts are entrained with strong magnetic fields, and discuss the
implications of this result for our understanding of the GRB phenomenon; (2) We
argue that the current gamma-ray burst (GRB) and X-ray flash (XRF) data are
consistent with a picture that all GRB-XRF jets are structured and
quasi-universal, with a typical Gaussian-like jet structure.


title: Planetary Collisions: Electromagnetic Signals

abstract:
  We investigate the electromagnetic signals accompanied with planetary
collisions and their event rate, and explore the possibility of directly
detecting such events. A typical Earth--Jupiter collision would give rise to a
prompt EUV-soft-X-ray flash lasting for hours and a bright IR afterglow lasting
for thousands of years. With the current and forthcoming observational
technology and facilities, some of these collisional flashes or the
post-collision remnants could be discovered.


title: A Rejuvenated Universe Without Initial Singularity

abstract:
  Cosmological observations strongly suggest the presence of dark energy which
comprises the majority of the current energy density of the universe. The
equation of state relating the pressure and energy density of this dark energy,
p = w \rho, appears to have w close to -1, with most analyses preferring w<-1
when these values are considered as part of the parameter space. If w<-1 is the
future behavior of the dark energy, the scale factor, expansion rate, and
energy density of the universe will diverge in a finite time as its apparent
expansion age tends to zero. We hypothesize that w>-1 is restored at a late
enough time, perhaps due to a phase transition of the dark energy, and show
that this produces conditions observationally indistinguishable from a Hot Big
Bang. This process of rejuvenation may have occurred in the past, making our
universe much older than it appears and eliminating the Big Bang singularity.


title: Light to Mass Variations with Environment

abstract:
  Large and well defined variations exist between the distribution of mass and
the light of stars on extragalactic scales. Mass concentrations in the range
10^12 - 10^13 M_sun manifest the most light per unit mass. Group halos in this
range are typically the hosts of spiral and irregular galaxies with ongoing
star formation. On average M/L_B ~ 90 M_sun/L_sun in these groups . More
massive halos have less light per unit mass. Within a given mass range, halos
that are dynamically old as measured by crossing times and galaxy morphologies
have distinctly less light per unit mass. At the other end of the mass
spectrum, below 10^12 M_sun, there is a cutoff in the manifestation of light.
Group halos in the range 10^11 - 10^12 M_sun can host dwarf galaxies but with
such low luminosities that M/L_B values can range from several hundred to
several thousand. It is suspected that there must be completely dark halos at
lower masses. Given the form of the halo mass function, it is the low relative
luminosities of the high mass halos that has the greatest cosmological
implications. Of order half the clustered mass may reside in halos with greater
than 10^14 M_sun. By contrast, only 5-10% of clustered mass would lie in
entities with less than 10^12 M_sun.


title:
Molecules in Southern Dense Cores I: Mopra and SEST Millimetre-Wave
  Observations

abstract:
  We have observed molecular-line transitions between 84 and 147 GHz in 24
dense southern molecular clouds with declinations south of -30 degrees using
the Mopra and SEST radio telescopes. The results of observations of 2-mm and
3-mm transitions of the molecules CO, CS, C2H, CH3OH, HCN, HNC, HCO+, HC3N,
OCS, HNCO and SO and several of their isotopomers are discussed in this paper,
including ratios of the emission from the 12C, 13C and 18O isotopomers of CO,
CS, HCO+, HCN and HNC. This paper lists the calibrated observational data for
each molecular cloud and discusses some general properties of this sample. The
calibration process for the Mopra antenna of the ATCA is described in an
appendix.


title: Cosmic distance-duality as probe of exotic physics and acceleration

abstract:
  In cosmology, distances based on standard candles (e.g. supernovae) and
standard rulers (e.g. baryon oscillations) agree as long as three conditions
are met: (1) photon number is conserved, (2) gravity is described by a metric
theory with (3) photons travelling on unique null geodesics. This is the
content of distance-duality (the reciprocity relation) which can be violated by
exotic physics. Here we analyse the implications of the latest cosmological
data sets for distance-duality. While broadly in agreement and confirming
acceleration we find a 2-sigma violation caused by excess brightening of SN-Ia
at z > 0.5, perhaps due to lensing magnification bias. This brightening has
been interpreted as evidence for a late-time transition in the dark energy but
because it is not seen in the d_A data we argue against such an interpretation.
Our results do, however, rule out significant SN-Ia evolution and extinction:
the "replenishing" grey-dust model with no cosmic acceleration is excluded at
more than 4-sigma despite this being the best-fit to SN-Ia data alone, thereby
illustrating the power of distance-duality even with current data sets.


title:
The VIRMOS deep imaging survey: III. ESO/WFI deep U-band imaging of the
  0226-04 deep field

abstract:
  In this paper we describe the U-band imaging of the F02 deep field, one of
the fields in the VIRMOS Deep Imaging Survey. The observations were done at the
ESO/MPG 2.2m telescope at La Silla (Chile) using the 8k x 8k Wide-Field Imager
(WFI). The field is centered at alpha(J2000)=02h 26m 00s and
delta(J2000)=-04deg 30' 00", the total covered area is 0.9 deg**2 and the
limiting magnitude (50% completeness) is U(AB) ~ 25.4 mag. Reduction steps,
including astrometry, photometry and catalogue extraction, are first discussed.
The achieved astrometric accuracy (RMS) is ~ 0.2" with reference to the I-band
catalog and ~ 0.07" internally (estimated from overlapping sources in different
exposures). The photometric accuracy including uncertainties from photometric
calibration, is < 0.1 mag. Various tests are then performed as a quality
assessment of the data. They include: (i) the color distribution of stars and
galaxies in the field, done together with the BVRI data available from the
VIMOS survey; (ii) the comparison with previous published results of U-band
magnitude-number counts of galaxies.


title:
Doppler broadening of the iron line and R-Gamma correlation in black
  hole binaries

abstract:
  RXTE/PCA observations of several black hole X-ray binaries in the low
spectral state revealed a tight correlation between spectral parameters and
characteristic frequencies of variability of X-ray flux. In particular, the
amplitude of reflection increases and the slope of Comptonized radiation
steepens as the noise frequencies increase. The data also suggest that there is
a correlated increase of the width of the Fe fluorescent line, probably related
to the Doppler broadening of the reflection features. Moreover, the width of
the line seems to follow DeltaE/E ~ nu_qpo^{1/3} law. If confirmed with higher
energy resolution observations, this result will have significant impact on the
models of the accretion flow and on our understanding of the nature of
characteristic frequencies of variability in X-ray binaries. In particular, it
will lend support to the truncated disk picture, confirming that the spectral
variations are indeed related to changes of the position of the inner disk
boundary and that characteristic variability frequencies are proportional to
the Keplerian frequency at the inner boundary of the accretion disk.


title: Neutron Star Structure with Hyperons and Quarks

abstract:
  We discuss the high-density nuclear equation of state within the
Brueckner-Hartree-Fock approach. Particular attention is paid to the effects of
nucleonic three-body forces, the presence of hyperons, and the joining with an
eventual quark matter phase. The resulting properties of neutron stars, in
particular the mass-radius relation, are determined. It turns out that stars
heavier than 1.3 solar masses contain necessarily quark matter.


title: Is there a hard tail in the Coma Cluster X-ray spectrum?

abstract:
  We report results from a re-analysis of the BeppoSAX observation of Coma and
from the analysis of a second, yet unpublished observation of the same object.
  From our re-analysis of the first observation we find that the statistical
evidence for a hard tail is about 2 sigma. From the analysis of the second
observation which, thanks to the lower background and the longer exposure time,
is characterized by a larger signal to noise we find no evidence for a hard
tail. From the upper limit on the flux of the hard tail, using the standard
Inverse Compton formulae, we derive a lower limit for the magnetic of about
0.2-0.4 microGauss consistent with Faraday rotation measurements.


title:
2MASS NIR photometry for 693 candidate globular clusters in M31 and the
  Revised Bologna Catalogue

abstract:
  We have identified in the 2MASS database 693 known and candidate globular
clusters in M31. The 2MASS J,H,K magnitudes of these objects have been
transformed to the same homogeneous photometric system of existing near
infrared photometry of M31 globulars, finally yielding J,H,K integrated
photometry for 279 confirmed M31 clusters, 406 unconfirmed candidates and 8
objects with controversial classification. Of these objects 529 lacked any
previous estimate of their near infrared magnitudes. The newly assembled near
infrared dataset has been implemented into a revised version of the Bologna
Catalogue of M31 globulars, with updated optical (UBVRI) photometry taken, when
possible, from the most recent sources of CCD photometry available in the
literature and transformed to a common photometric system. The final Revised
Bologna Catalogue (available in electronic form) is the most comprehensive list
presently available of confirmed and candidate M31 globular clusters, with a
total of 1164 entries. In particular, it includes 337 confirmed GCs, 688 GC
candidates, 10 objects with controversial classification, 70 confirmed
galaxies, 55 confirmed stars, and 4 HII regions lying within ~3 deg. from the
center of the M31 galaxy. Using the newly assembled database we show that the
V-K color provides a powerful tool to discriminate between M31 clusters and
background galaxies, and we identify a sample of 83 globular cluster
candidates, which is not likely to be contaminated by misclassified galaxies.


title: Interpreting QPOs from Accreting Neutron Stars

abstract:
  The high time resolution and large area of the Rossi X-ray Timing Explorer
have been essential in the detection and characterization of high-frequency
quasi-periodic variability in the flux from neutron stars in low-mass X-ray
binaries. An unknown phenomenon prior to RXTE, kilohertz quasi-periodic
oscillations (QPOs) have now been detected from more than twenty systems. Their
high frequencies (up to 1330 Hz) imply that they are generated close to the
neutron star, where general relativistic effects are expected to play an
important role. I summarize current models for the kilohertz QPO phenomenon. In
particular, I show that there is a significant domain of agreement among the
models that can be used to constrain neutron star structure and look for
signatures of highly curved spacetime in the properties of the QPOs.


title: What We Already Know About Quintessence

abstract:
  Good tracking requires significant quintessence energy fraction, even in the
past, but a potential that is not yet truly slow-rolling. The supernova bound
on cosmic acceleration excludes constant equation of state and inverse power
potentials, but allows the SUGRA potential and other good trackers, in which
quintessence energy domination and kinetic energy suppression {\em both} began
only recently. This makes the time in which we live special in {\em two}
respects.


title: Large Scale Structure in the ELAIS S1 Survey

abstract:
  We present an analysis of the two-point angular correlation function of the
ELAIS S1 survey. The survey covers 4 deg$^2$ and contains 462 sources detected
at 15$\mu$m to a 5$\sigma$ flux limit of 0.45 mJy. Using the 329 extragalactic
sources not repeated in different observations, we detect a significant
clustering signal; the resulting angular correlation function can be fitted by
a exponential law $w(\theta) = A \theta^{1-\gamma}$ with $A = 0.014\pm0.005$
and $\gamma = 2.04\pm0.18$. Assuming a redshift distribution of the objects, we
invert Limber's equation and deduce a spatial correlation length
$r_0=4.3^{+0.4}_{-0.7} h^{-1}$ Mpc. This is smaller than that obtained from
optical surveys but it is in agreement with results from IRAS. This extends to
higher redshift the observational evidence that infrared selected surveys show
smaller correlation lengths (i.e. reduced clustering amplitudes) than optical
surveys.


title: Strangeness in Neutron Stars

abstract:
  We discuss the role of strangeness on the internal constitution and
structural properties of neutron stars. In particular, we report on recent
calculations of hyperon star properties derived from microscopic equations of
state for hyperonic matter. Next, we discuss the possibility of having a
strange quark matter core in a neutron star, or the possible existence of
strange quark matter stars, the so-called strange stars.


title: Unveiling Radio Loudness in Quasars

abstract:
  We present a new approach to tackle the issue of radio loudness in quasars.
We constrain a (simple) prescription for the intrinsic distribution of
radio-to-optical ratios by comparing properties of Monte Carlo simulated
samples with those of observed optically selected quasars. We find strong
evidence for a dependence of the radio luminosity on the optical one, even
though with a large scatter. The intrinsic distribution of the radio-to-optical
ratios shows a peak at R*{1.4} ~ 0.3, with only ~5 per cent of objects being
included in a high R*{1.4} tail which identifies the radio loud regime.


title: The Off-Axis Galaxy Cluster Merger Abell 115

abstract:
  We have used a 50.4 ksec Chandra obsffervation to examine the galaxy cluster
Abell 115 (z=0.1971). The X-ray surface brightness distribution shows a merger
of 2 sub-clusters with substantial off-axis motion. The northern sub-cluster
moves toward the southwest and exhibits a strong X-ray surface brightness
gradient toward this direction as well as a "fan" of X-ray bright Intra-Cluster
Medium (ICM) toward the northeast. The southern sub-cluster shows a pronounced
northeast-southwest elongation, probably as a consequence of the ongoing
merger. The temperature of the ICM is highly non-uniform across the cluster.
Although the merger is well underway and has had a substantial influence on the
morphology of the 2 sub-clusters, it has apparently not disturbed the cool
sub-cluster cores. The ICM in between the sub-clusters has a significantly
elevated temperature of ~8 keV. However, owing to the low surface brightness,
we do not find direct evidence for shocks in this region. The X-ray surface
brightness distribution of the northern sub-cluster is highly non-uniform. The
data show a bright central core region of about 10" (30 kpc) diameter. A highly
significant surface brightness discontinuity separates the core from the
ambient ICM. We discuss several possibilities to explain the compact core, and
its relation to the central radio galaxy 3C 28.0 and the sub-cluster's cooling
flow. Further outwards, at about 24.6" (80 kpc) to the southwest of the
sub-cluster core, the surface brightness distribution shows a jump associated
with a contact discontinuity. The Chandra imaging spectroscopy data do not show
evidence for a shock associated with the surface brightness jump. We conclude
that it is associated with denser plasma moving sub-sonically through the
ambient plasma.


title: A 1200 micron MAMBO Survey of the ELAIS N2 and Lockman Hole East Fields

abstract:
  Using the MPIfR Max Planck Millimeter Bolometer array (MAMBO) on the IRAM 30m
Telescope we have mapped the ELAIS N2 and Lockman Hole East Fields at 1200
micron to a rms noise level of 0.8-1.0 mJy per 11" beam. The areas surveyed are
326 arcmin^2 in the ELAIS N2 field and 212 arcmin^2 in the Lockman Hole,and
cover the 260 arcmin^2 previously observed by SCUBA [5].


title: Accretion onto a Primordial Protostar

abstract:
  We present a three-dimensional numerical simulation that resolves the
formation process of a Population III star down to a scale of ~100 AU. The
simulation is initialized on the scale of a dark matter halo of mass ~10^6
M_sun that virializes at z~20. It then follows the formation of a
fully-molecular central core, and traces the accretion from the diffuse
dust-free cloud onto the protostellar core for as long as ~10^4 yr, at which
time the core has grown to ~50 M_sun. We find that the accretion rate starts
very high, ~0.1 M_sun yr^-1, and declines rapidly thereafter approaching a
power-law temporal scaling. Asymptotically, at times t > 10^3 yr after core
formation, the stellar mass grows approximately as M_star=20 M_sun (t/10^3
yr)^0.4. Earlier on, accretion is faster with M_star \propto t^0.75. By
extrapolating this growth over the full lifetime of very massive stars,
t~3x10^6 yr, we obtain the conservative upper limit M_star < 500 M_sun. The
actual stellar mass is, however, likely to be significantly smaller than this
mass limit due to radiative and mechanical feedback from the protostar.


title: An XMM-Newton view of M101: I. The luminous X-ray source population

abstract:
  We present the first results of an XMM-Newton EPIC observation of the
luminous X-ray source population in the supergiant spiral galaxy M101. We have
studied the properties of the fourteen most luminous sources, all of which have
intrinsic X-ray luminosities exceeding the Eddington limit for a 1.4 solar mass
neutron star, with a subset in the ultraluminous X-ray source (ULX) regime.
Eleven sources show evidence of short-term variability, and most vary by a
factor of ~2-4 over a baseline of 11-24 yrs, providing strong evidence that
these sources are accreting X-ray binary (XRB) systems. The sources show a
variety of spectral shapes, with no apparent spectral distinction between those
above and below the ULX threshold. Nine are well-fit with either simple
absorbed disc blackbody/powerlaw models. However for three of the four sources
best-fit with powerlaw models, we cannot exclude the disc blackbody fits and
therefore conclude that, coupled with their high luminosities, eight out of
nine single-component sources are possibly high state XRBs. The nuclear source
has the only unambiguous powerlaw spectrum (photon index~2.3), which may be
evidence for a low-luminosity AGN. The remaining five sources require at least
two-component spectral fits. We have compared the spectral shapes of nine
sources covered by both this observation and an archival 100ks Chandra
observation of M101; the majority show behaviour typical of Galactic XRBs i.e.
softening with increasing luminosity. We find no definitive spectral signatures
to indicate that these sources contain neutron star primaries, and conclude
that they are likely to be stellar-mass black hole XRBs, with black hole masses
of ~2-23 solar masses if accreting at the Eddington limit (abridged).


title: KH 15D: Gradual Occultation of a Pre-Main-Sequence Binary

abstract:
  We propose that the extraordinary ``winking star'' KH 15D is an eccentric
pre-main-sequence binary that is gradually being occulted by an opaque screen.
This model accounts for the periodicity, depth, duration, and rate of growth of
the modern eclipses; the historical light curve from photographic plates; and
the existing radial velocity measurements. It also explains the re-brightening
events that were previously observed during eclipses, and the subsequent
disappearance of these events. We predict the future evolution of the system
and its full radial velocity curve. Given the small velocity of the occulting
screen relative to the center of mass of the binary, the screen is probably
associated with the binary, and may be the edge of a precessing circumbinary
disk.


title:
Three Lyman-alpha Emitters at z approx 6: Early GMOS/Gemini Data from
  the GLARE Project

abstract:
  We report spectroscopic detection of three z~6 Lyman-alpha emitting galaxies,
in the vicinity of the Hubble Ultra Deep Field, from the early data of the
Gemini Lyman-$\alpha$ at Reionisation Era (GLARE) project. Two objects,
GLARE#3001 (z =5.79) and GLARE#3011 (z =5.94), are new detections and are
fainter in $z'$ (z'_{AB} =26.37 and 27.15) than any Lyman break galaxy
previously detected in Lyman-alpha. A third object, GLARE#1042 (z =5.83) has
previously been detected in line emission from the ground; we report here a new
spectroscopic continuum detection. Gemini/GMOS-S spectra of these objects,
obtained using nod & shuffle, are presented together with a discussion of their
photometric properties. All three objects were selected for spectroscopy via
the i-drop Lyman Break technique, the two new detections from the GOODS v1.0
imaging data. The red i'-z' colors and high equivalent widths of these objects
suggest a high-confidence z>5 Lyman-alpha identification of the emission lines.
This brings the total number of known z>5 galaxies within 9 arcmin of the
Hubble Ultra Deep Field to four, of which three are at the same redshift (z=5.8
within 2000 km/s suggesting the existence of a large-scale structure at this
redshift.


title:
Aerogel keystones: extraction of complete hypervelocity impact events
  from aerogel collectors

abstract:
  In January 2006, the Stardust mission will return the first samples from a
solid solar-system body since Apollo, and the first samples of contemporary
interstellar dust ever collected. Although sophisticated laboratory instruments
exist for the analysis of Stardust samples, techniques for the recovery of
particles and particle residues from aerogel collectors remain primitive. Here
we describe our recent progress in developing techniques for extracting small
volumes of aerogel, which we have called ``keystones,'' which completely
contain particle impacts but minimize the damage to the surrounding aerogel
collector. These keystones can be fixed to custom-designed micromachined
silicon fixtures (so-called ``microforklifts''). In this configuration the
samples are self-supporting, which can be advantageous in situations in which
interference from a supporting substrate is undesirable. The keystones may also
be extracted and placed onto a substrate without a fixture. We have also
demonstrated the capability of homologously crushing these unmounted keystones
for analysis techniques which demand flat samples.


title:
Large-Scale Model of the Milky Way: Stellar Kinematics and Microlensing
  Event Timescale Distribution in the Galactic Bulge

abstract:
  We build a stellar-dynamical model of the Milky Way barred bulge and disk,
using a newly implemented adaptive particle method. The underlying mass model
has been previously shown to match the Galactic near-infrared surface
brightness as well as gas-kinematic observations. Here we show that the new
stellar-dynamical model also matches the observed stellar kinematics in several
bulge fields, and that its distribution of microlensing event timescales
reproduces the observed timescale distribution of the {\it MACHO} experiment
with a reasonable stellar mass function. The model is therefore an excellent
basis for further studies of the Milky Way. We also predict the observational
consequences of this mass function for parallax shifted events.


title:
The Stellar Halo in the Large Magellanic Cloud: Mass, Luminosity, and
  Microlensing Predictions

abstract:
  Recently obtained kinematic data has shown that the Large Magellanic Cloud
(LMC) possesses an old stellar halo. In order to further characterize the
properties of this halo, parametric King models are fit to the surface density
of RR Lyrae stars. Using data from both the MACHO and OGLE II microlensing
surveys, the model fits yield the center of their distribution at RA =
05:21.1+-0.8, Dec = -69:45+-6 (J2000) and a core radius of 1.42+-0.12 kpc. As a
check the halo model is compared with RR Lyrae star counts in fields near the
LMC's periphery previously surveyed with photographic plates. These data,
however, require a cautious interpretation. Several topics regarding the LMC
stellar halo are discussed. First, the properties of the halo imply a global
mass-to-light ratio of M/L_V = 5.3+-2.1 and a total mass of 1.6+-0.6 10^10
M_sun for the LMC in good agreement with estimates based on the rotation curve.
Second, although the LMC's disk and halo are kinematically distinct, the shape
of the surface density profile of the halo is remarkably similar to that of the
young disk. For example, the best-fit exponential scale length for the RR Lyrae
stars is 1.47+-0.08 kpc, which compares to 1.46 kpc for the LMC's blue light.
In the Galaxy, the halo and disk do not resemble each other like this. Finally,
a local maximum in the LMC's microlensing optical depth due to halo-on-disk
stellar self-lensing is predicted. For the parameters of the stellar halo
obtained, this maximum is located near MACHO events LMC-4 and LMC-23, and is
large enough to possibly account for these two events, but not for all of the
observed microlensing.


title:
New constraints on the mass composition of cosmic rays above 10^17 eV
  from Volcano Ranch measurements

abstract:
  Linsley used the Volcano Ranch array to collect data on the lateral
distribution of showers produced by cosmic rays at energies above 10^17 eV.
Very precise measurements of the steepness of the lateral distribution function
were made on 366 events. The current availability of sophisticated hadronic
interaction models has prompted an interpretation of the measurements. In this
analysis we use the AIRES Monte Carlo code to generate showers, together with
GEANT4 to simulate the detector response to ground particles. The results show
that, with the assumption of a bi-modal proton and iron mix, iron is the
dominant component of cosmic rays between 5x10^17 and 10^19 eV, assuming that
hadronic interactions are well-described by QGSJET at this energy range.


title: Supernova Properties from Shock Breakout X-rays

abstract:
  We investigate the potential of the upcoming LOBSTER space observatory (due
circa 2009) to detect soft X-ray flashes from shock breakout in supernovae,
primarily from Type II events. LOBSTER should discover many SN breakout
flashes, although the number is sensitive to the uncertain distribution of
extragalactic gas columns. X-ray data will constrain the radii of their
progenitor stars far more tightly than can be accomplished with optical
observations of the SN light curve. We anticipate the appearance of blue
supergiant explosions (SN 1987A analogs), which will uncover a population of
these underluminous events. We consider also how the mass, explosion energy,
and absorbing column can be constrained from X-ray observables alone and with
the assistance of optically-determined distances. These conclusions are drawn
using known scaling relations to extrapolate, from previous numerical
calculations, the LOBSTER response to explosions with a broad range of
parameters. We comment on a small population of flashes with 0.2 < z < 0.8 that
should exist as transient background events in XMM, Chandra, and ROSAT
integrations.


title:
Transitions of black hole transients to the low/hard state under the
  microscope

abstract:
  We characterized the evolution of spectral and temporal properties of several
Galactic black hole transients observed between 1996-2001 using the data from
well sampled PCA observations close to the transition to the low/hard state. We
showed that the changes in temporal properties are much sharper than the
changes in the spectral properties, and it is much easier to identify a state
transition with the temporal properties. The ratio of the power-law flux to the
total flux in the 3-25 keV band increases close to the transition, and the
power-law flux shows a sharp increase along with the changes in temporal
properties during the transitions. In this work we concentrate on the decay of
two recent outbursts, from 4U 1543$-$47, and H1743$-$322 and discuss the state
transitions by tracking their daily, and sometimes hourly evolution, and
interpret results based on the expectations from our earlier observations.


title:
The X-ray Variability of NGC 4945: Characterizing the Power Spectrum
  through Light Curve Simulations

abstract:
  For light curves sampled on an uneven grid of observation times, the shape of
the power density spectrum (PDS) includes severe distortion effects due to the
window function, and simulations of light curves are indispensable to recover
the true PDS. We present an improved method for comparing light curves
generated from a PDS model to the measured data and apply it to a 50-day long
RXTE observations of NGC 4945, a Seyfert 2 galaxy with well-determined mass
from megamaser observations. The improvements over previously reported
investigations include the adjustment of the PDS model normalization for each
simulated light curve in order to directly investigate how well the chosen PDS
shape describes the source data. We furthermore implement a robust
goodness-of-fit measure that does not depend on the form of the variable used
to describe the power in the periodogram. We conclude that a knee-type function
(smoothly broken power law) describes the data better than a simple power law;
the best-fit break frequency is ~10^-6 Hz.


title:
The Distribution of Metallicity in the IGM at z~2.5: OVI and CIV
  Absorption in the Spectra of 7 QSOs

abstract:
  We present a direct measurement of the metallicity distribution function for
the high redshift intergalactic medium. We determine the shape of this function
using survival statistics, which account for both detections and non-detections
of OVI and CIV associated with HI absorption in quasar spectra. Our OVI sample
probes the metal content of ~50% of all baryons at z~2.5. We find a median
intergalactic abundance of [O,C/H]=-2.82; the differential abundance
distribution is approximately lognormal with mean <[C,O/H]>~-2.85 and
\sigma=0.75 dex. Some 60-70% the Lya forest lines are enriched to observable
levels ([O,C/H]>-3.5) while the remaining ~30% of the lines have even lower
abundances. Thus we have not detected a universal metallicity floor as has been
suggested for some Population III enrichment scenaria. In fact, we argue that
the bulk of the intergalactic metals formed later than the first stars that are
thought to have triggered reionization. We do not observe a significant trend
of decreasing metallicity toward the lower density IGM, at least within regions
that would be characterized as filaments in numerical simulations. However, an
[O/H] enhancement may be present at somewhat high densities. We estimate that
roughly half of all baryons at these redshifts have been enriched to
[O/H]>=-3.5. We develop a simple model for the metallicity evolution of the
IGM, to estimate the chemical yield of galaxies formed prior to z~2.5. We find
that the typical galaxy recycled 0.1-0.4% of its mass back into the IGM as
heavy elements in the first 3 Gyr after the Big Bang.


title: Composition of Cosmic Rays with the Energy more than 4x10^{19} eV

abstract:
  Arrival directions of extensive air showers by using world data are
considered. It is found that the shower distribution in zenith angle at the
energies E>10^{19} eV and E>4x10^{19} eV differs from each other. By our
estimations, the shower with E>10^{20} eV at the Sugar array was not
registered. The mass composition of very high-energy cosmic rays has been
estimated. It is shown that E>4x10^{19} eV cosmic rays are, most likely, super
heavy nuclei with charge Z>26.


title: Weak lensing of the Sunyaev-Zel'dovich sky

abstract:
  We address the question of whether the angular power spectrum of the thermal
Sunyaev-Zel'dovich (SZ) sky is further distorted by weak gravitational lensing
of foreground large-scale structures. Using an analytic approach to both
gaseous and dark halo models, we show that the contamination of weak lensing in
the measurement of SZ power power is negligibly small, and relatively
corrections |\Delta C_l|/C_l are less than 3% up to l=10^5. This arises from
both the weaker gravitational potentials of low-redshift matter inhomogeneities
that can act as lenses for SZ sources (clusters) and the shallower shape of
intrinsic SZ power spectrum at large l, in contrast to the cosmic microwave
background which can be significantly affected by weak lensing because of the
distant location and significant damping of its intrinsic power spectrum at
small angular scales.


title: The Future of X-ray Spectroscopy of Galactic Black Hole Binaries

abstract:
  There are four major X-ray satellites currently in operation, with two more
shortly to follow, and several very ambitious observatories in various stages
of planning. This very rich period of X-ray observation is leading to great
advances in our understanding of the accretion flow onto the black hole,
although we are quickly learning (or perhaps better put, remembering) exactly
how complicated this flow can be. This review was meant to assess future
prospects for X-ray spectroscopy of black hole binaries; however, I first look
backward to the observations and theories that helped us arrive at our current
`paradigm'. I then discuss current and near-future spectroscopic studies, which
increasingly (and very fruitfully) treat X-ray spectroscopy as part of a
larger, intimately connected picture along with radio, optical, and gamma-ray
spectroscopy. Equally importantly, and in large part thanks to the success of
RXTE, there is now a strong realization that spectral-temporal correlations,
even across wavelength bands, are crucial to our understanding of the physics
of these systems. Going forward, we are well-poised to continue to advance our
knowledge via X-ray spectroscopy, both with existing satellites that have a
long lifetime ahead of them, and with the next generation of instruments. If
there is any `hole' in this bright future, it is the potential loss of RXTE,
with no designated follow-up mission. Studies of multi-wavelength
spectral-temporal correlations will become more difficult due to the loss of
two important attributes of RXTE: its fast timing capabilities and its
extremely flexible scheduling which has made many of these studies possible.


title: An alternative look at the snowline in protoplanetary disks

abstract:
  We have calculated an evolution of protoplanetary disk from an extensive set
of initial conditions using a time-dependent model capable of simultaneously
keeping track of the global evolution of gas and water-ice. A number of
simplifications and idealizations allows for an embodiment of gas-particle
coupling, coagulation, sedimentation, and evaporation/condensation processes.
We have shown that, when the evolution of ice is explicitly included, the
location of the snowline has to be calculated directly as the inner edge of the
region where ice is present and not as the radius where disk's temperature
equals the evaporation temperature of water-ice. The final location of the
snowline is set by an interplay between all involved processes and is farther
from the star than implied by the location of the evaporation temperature
radius. The evolution process naturally leads to an order of magnitude
enhancement in surface density of icy material.


title: Element segregation in giant galaxies and X-ray clusters

abstract:
  We examine the process of element segregation by gravity in giant elliptical
galaxies and X-ray clusters. We solve the full set of flow equations developed
by Burgers for a multi-component fluid, under the assumption that magnetic
fields slow the diffusion by a constant factor F_B. Compared to the previous
calculations that neglected the residual heat flow terms, we find that
diffusion is faster by ~20%. In clusters we find that the diffusion changes the
local abundance typically by factors of 1+0.3(T/10^8 K)^1.5/F_B and
1+0.15(T/10^8 K)^1.5/F_B for helium and heavy elements, respectively, where T
is the gas temperature. In elliptical galaxies, the corresponding factors are
1+0.2(T/10^7 K)^1.5/F_B and 1+0.1(T/10^7 K)^1.5/F_B, respectively. If the
suppression factor F_B is modest, diffusion could significantly affect
observational properties of hot X-ray clusters and cD galaxies. In particular,
diffusion steepens the baryon distribution, increases the total X-ray
luminosity, and changes the spectrum and evolution of stars that form out of
the helium-rich gas. Detection of these diffusion signatures would allow to
gauge the significance of the magnetic fields, which also inhibit thermal heat
conduction as a mechanism for eliminating cooling flows in the same
environments.


title: Effects of BBN on Population III stars

abstract:
  The presence (or absence) of CNO elements in the primordial gas determines
different behaviours in population III stars formation and evolution: we
therefore present an analysis of the main channels for the synthesis of these
elements in BBN in order to understand, within a reliable interval, their
abundance in the primordial material.


title:
Star formation history and dust attenuation in galaxies drawn from
  ultraviolet surveys

abstract:
  We compile a new sample of 115 nearby, non-Seyfert galaxies spanning a wide
range of star formation activities, from starburst to nearly dormant, based on
ultraviolet (UV) observations with various satellites. We combine these
observations with infrared (IR) observations to study the relation between
ratio of total far-IR to UV luminosities and UV spectral slope (the `IRX-UV'
relation). We show that, at fixed UV spectral slope, quiescent star-forming
galaxies in our sample have systematically lower ratio of total far-IR to UV
luminosities than starburst galaxies. The strengths of spectral indices
sensitive to star formation history, such as the 4000 A break and EW(Ha),
correlate well with distance from the mean relation for starburst galaxies in
the IRX-UV diagram, while there is little or no correlation between the
dust-sensitive Ha/Hb ratio and this distance. This is strong observational
evidence that the star formation history is relevant to the `second parameter'
affecting the IRX-UV relation. We show that these results can be understood in
the framework of the simple model of Charlot & Fall 2000 for the transfer of
starlight through the ISM in galaxies. We confirm that, for starburst galaxies,
the tight IRX-UV relation can be understood most simply as a sequence in
overall dust content. In addition, we find that the broadening of the relation
for quiescent star-forming galaxies can be understood most simply as a sequence
in the ratio of present to past-averaged star formation rates. We provide
simple formulae for estimating the UV attenuation as a function of either the
ratio of far-IR to UV luminosities or the UV spectral slope and show that the
accuracy of these estimates can be improved if some constraints are available
on the ratio of present to past-averaged star formation rates [abridged].


title:
Ultra High Energy Cosmic Rays: the present position and the need for
  mass composition measurements

abstract:
  The present situation with regard to experimental data on ultra high-energy
cosmic rays is briefly reviewed. Whilst detailed knowledge of the shape of the
energy spectrum is still lacking, it is clear that events above 10^20 eV do
exist. Evidence for clustering of the directions of some of the highest energy
events remains controversial. Clearly, more data are needed and these will come
from the southern branch of the Pierre Auger Observatory in the next few years.
What is evident is that our knowledge of the mass composition of cosmic rays is
deficient at all energies above 10^18 eV. It must be improved if we are to
discover the origin of the highest energy cosmic rays. The major part of the
paper is concerned with this problem: it is argued that there is no compelling
evidence to support the common assumption that cosmic rays of the highest
energies are protons.


title:
On the Surface Heating of Synchronously-Spinning Short-Period Jovian
  Planets

abstract:
  We consider the atmospheric flow on short-period extra-solar planets through
two-dimensional numerical simulations of hydrodynamics with radiation transfer.
One side is always exposed to the irradiation from the host star. The other is
always in shadow. The temperature of the day side is determined by the
equilibrium which the planetary atmosphere establishes with stellar radiation.
Part of the thermal energy deposited on the day side is advected to the night
side by a current. The radiation transfer, the night-side temperature
distribution and by this the spectroscopic signature of the planet are
sensitive functions of the atmospheric opacity. If the atmosphere contains
grains with an abundanceand size distribution comparable to that of the
interstellar medium, shallow heating occurs on the day side and the night side
cools well below the day side. The temperature difference decreases as the
abundance of grains is reduced. A simple analytic model of the dissipation of
the circulation flow and associated kinetic heating is considered. This heating
effect occurs mostly near the photosphere, not deep enough to significantly
affect the size of planets. We show that the surface irradiation suppresses
convection near the photospheric region on the day side. In some cases
convection zones appear near the surface on the night side. This structural
modification may influence the response and dissipation of tidal disturbances
and alter the circularization and synchronization time scales.


title: Time-resolved photometry of cataclysmic variables

abstract:
  We present time-resolved photometry of two cataclysmic variables whose CCD
photometric observations were obtained with the 1m telescope at the South
African Astronomical Observatory in October 2002 and August 2003 and with the
1m telescope at Hoher List in Germany. Concerning MCT 2347-3144 we detect for
the first time a period of 6.65h. For V1193 Ori the 3.96 h periodicity has for
the first time been confirmed through time-resolved photometry.


title:
WFI J2026-4536 and WFI J2033-4723: Two New Quadruple Gravitational
  Lenses

abstract:
  We report the discovery of two new gravitationally lensed quasars, WFI
J2026-4536 and WFI J2033-4723, at respective source redshifts of z=2.23 and
z=1.66. Both systems are quadruply imaged and have similar PG1115-like image
configurations. WFI J2026-4536 has a maximum image separation of 1.4", a total
brightness of g = 16.5, and a relatively simple lensing environment, while WFI
J2033-4723 has a maximum image separation of 2.5", an estimated total
brightness of g = 17.9, and a more complicated environment of at least six
galaxies within 20". The primary lensing galaxies are detected for both systems
after PSF subtraction. Several of the broadband flux ratios for the two lenses
show a strong (0.1-0.4 mags) trend with wavelength, suggesting either
microlensing or differential extinction through the lensing galaxy. For WFI
J2026-4536, the total quasar flux has dimmed by 0.1 mag in the blue but only
half as much in the red over three months, suggestive of microlensing-induced
variations. For WFI J2033-4723, resolved spectra of some of the quasar
components reveal emission line flux ratios that agree better with the
macromodel predictions than either the broadband or continuum ratios, also
indicative of microlensing. The predicted differential time delays for WFI
J2026-4536 are short, ranging from 1-2 weeks for the long delay, but are longer
for WFI J2033-4723, ranging from 1-2 months. Both systems hold promise for
future monitoring campaigns aimed at microlensing or time delay studies.


title: Detection of Saturnian X-ray emission with XMM-Newton

abstract:
  The giant planet Saturn was observed by XMM-Newton in September 2002. We
present and analyse these XMM-Newton observations and compare our findings to
the Chandra observations of Saturn. Contamination of the XMM-Newton data by
optical light is found to be severe in the medium and thin filters, but with
the thick filter all optical light is sufficiently blocked and the signal
observed in this filter is interpreted as genuine X-ray emission, which is
found to qualitatively and quantitatively resemble Saturn's Chandra spectrum
very well.