title: Experimental Mg IX photorecombination rate coefficient

abstract:
  The rate coefficient for radiative and dielectronic recombination of
berylliumlike magnesium ions was measured with high resolution at the
Heidelberg heavy-ion storage ring TSR. In the electron-ion collision energy
range 0-207 eV resonances due to 2s -> 2p (Delta N = 0) and 2s -> 3l (Delta
N=1) core excitations were detected. At low energies below 0.15 eV the
recombination rate coefficient is dominated by strong 1s2 (2s 2p 3P) 7l
resonances with the strongest one occuring at an energy of only 21 meV. These
resonances decisively influence the Mg IX recombination rate coefficient in a
low temperature plasma. The experimentally derived Mg IX dielectronic
recombination rate coefficient (+-15% systematical uncertainty) is compared
with the recommendation by Mazzotta et al. (1998, A&AS, 133, 403) and the
recent calculations by Gu (2003, ApJ, 590, 1131) and by Colgan et al. (2003,
A&A, 412, 597). These results deviate from the experimental rate coefficient by
130%, 82% and 25%, respectively, at the temperature where the fractional
abundance of Mg IX is expected to peak in a photoionized plasma. At this
temperature a theoretical uncertainty in the 1s2 (2s 2p 3P) 7l resonance
positions of only 100 meV would translate into an uncertainty of the plasma
rate coefficient of almost a factor 3. This finding emphasizes that an accurate
theoretical calculation of the Mg IX recombination rate coefficient from first
principles is challenging.


title:
Dust in Brown Dwarfs IV. Dust formation and driven turbulence on
  mesoscopic scales

abstract:
  Dust formation in brown dwarf atmospheres is studied by utilising a model for
driven turbulence in the mesoscopic scale regime. We apply a pseudo-spectral
method where waves are created and superimposed within a limited wavenumber
interval. The turbulent kinetic energy distribution follows the Kolmogoroff
spectrum which is assumed to be the most likely value. Such superimposed,
stochastic waves may occur in a convectively active environment. They cause
nucleation fronts and nucleation events and thereby initiate the dust formation
process which continues until all condensible material is consumed. Small
disturbances are found to have a large impact on the dust forming system. An
initially dust-hostile region, which may originally be optically thin, becomes
optically thick in a patchy way showing considerable variations in the dust
properties during the formation process. The dust appears in lanes and curls as
a result of the interaction with waves, i.e. turbulence, which form larger and
larger structures with time. Aiming on a physical understanding of the
variability of brown dwarfs, related to structure formation in substellar
atmospheres, we work out first necessary criteria for small-scale closure
models to be applied in macroscopic simulations of dust forming astrophysical
systems.


title: The (un)resolved X-ray background in the Lockman Hole

abstract:
  Most of the soft and a growing fraction of the harder X-ray background has
been resolved into emission from point sources, yet the resolved fraction above
7 keV has only been poorly constrained. We use ~700 ks of XMM-Newton
observations of the Lockman Hole and a photometric approach to estimate the
total flux attributable to resolved sources in a number of different energy
bands. We find the resolved fraction of the X-ray background to be ~90 per cent
below 2 keV but it decreases rapidly at higher energies with the resolved
fraction above ~7 keV being only ~50 per cent. The integrated X-ray spectrum
from detected sources has a slope of Gamma~1.75, much softer than the Gamma=1.4
of the total background spectrum. The unresolved background component has the
spectral signature of highly obscured AGN.


title:
Two clocks in the PSR J0737--3039 binary system and their implications
  for the system's origin and evolution

abstract:
  As discussed elsewhere in these proceedings, the double pulsar system is a
magnificent laboratory for gravitational physics and for studying pulsar
magnetospheres. Here we consider the uses of having two clocks in the system in
the context of its origin and evolution. We find that the ``standard''
evolutionary scenario involving spin-up of the first-born neutron star in an
X-ray binary phase is consistent with the observed parameters. Equality of the
spin-down ages of the two pulsars requires that the post-accretion spin period
of A most likely lies in the range $16 \lapp P_{\rm 0,A} \lapp 21$ ms. The
likely age of the system is 30-70 Myr.


title:
The 2dF Galaxy Redshift Survey: stochastic relative biasing between
  galaxy populations

abstract:
  It is well known that the clustering of galaxies depends on galaxy type.Such
relative bias complicates the inference of cosmological parameters from galaxy
redshift surveys, and is a challenge to theories of galaxy formation and
evolution. In this paper we perform a joint counts-in-cells analysis on
galaxies in the 2dF Galaxy Redshift Survey, classified by both colour and
spectral type, eta, as early or late type galaxies. We fit three different
models of relative bias to the joint probability distribution of the cell
counts, assuming Poisson sampling of the galaxy density field. We investigate
the nonlinearity and stochasticity of the relative bias, with cubical cells of
side 10Mpc \leq L \leq 45Mpc (h=0.7). Exact linear bias is ruled out with high
significance on all scales. Power law bias gives a better fit, but likelihood
ratios prefer a bivariate lognormal distribution, with a non-zero
`stochasticity' - i.e. scatter that may result from physical effects on galaxy
formation other than those from the local density field. Using this model, we
measure a correlation coefficient in log-density space (r_LN) of 0.958 for
cells of length L=10Mpc, increasing to 0.970 by L=45Mpc. This corresponds to a
stochasticity sigma_b/bhat of 0.44\pm0.02 and 0.27\pm0.05 respectively. For
smaller cells, the Poisson sampled lognormal distribution presents an
increasingly poor fit to the data, especially with regard to the fraction of
completely empty cells. We compare these trends with the predictions of
semianalytic galaxy formation models: these match the data well in terms of
overall level of stochasticity, variation with scale, and fraction of empty
cells.


title:
The nature of the relative bias between galaxies of different spectral
  type in 2dFGRS

abstract:
  We present an analysis of the relative bias between early- and late-type
galaxies in the Two-degree Field Galaxy Redshift Survey (2dFGRS). Our analysis
examines the joint counts in cells between early- and late-type galaxies, using
approximately cubical cells with sides ranging from 7h^{-1}Mpc to 42h^{-1}Mpc.
We measure the variance of the counts in cells using the method of Efstathiou
et al. (1990), which we find requires a correction for a finite volume effect.
We fit lognormal models to the one-point density distribution and develop
methods of dealing with biases in the recovered variances resulting from this
technique. We directly fit deterministic models for the joint density
distribution function, f(delta_E,delta_L), to the joint counts in cells using a
maximum likelihood technique. Our results are consistent with a scale invariant
relative bias factor on all scales studied. Linear bias is ruled out on scales
less than l=28h^{-1}Mpc. A power-law bias model is a significantly better fit
to the data on all but the largest scales studied; the relative goodness of fit
of this model as compared to that of the linear bias model suggests that any
nonlinearity is negligible for l>~40h^{-1}Mpc, consistent with the expectation
from theory that the bias should become linear on large scales. (abridged)


title: The History of Astrophysics in Antarctica

abstract:
  We examine the historical development of astrophysical science in Antarctica
from the early 20th century until today. We find three temporally overlapping
eras, each having a rather distinct beginning. These are the astrogeological
era of meteorite discovery, the high energy era of particle detectors, and the
photon astronomy era of microwave, sub--mm and infrared telescopes, sidelined
by a few niche experiments at optical wavelengths. The favourable atmospheric
and geophysical conditions are briefly examined, followed by an account of the
major experiments and a summary of their results.


title: Comparing AGN broad- and narrow-line regions

abstract:
  We compare recent HST observations of Seyfert and quasar NLRs and find that
type-2 AGNs follow a relation consistent with that expected for a distribution
of gas ionized by a central source R(NLR,2) \propto L^{0.32 +/- 0.05}, while
type-1 objects are fit with a steeper slope of 0.55 +/- 0.05. The latter is
comparable to the scaling found for the BLR size with continuum luminosity
(slope: 0.5-0.7). Therefore, we investigate what we can learn about the BLR
size if the NLR size is only determined by the AGN luminosity. We find that NLR
and BLR size are related linearly following R(BLR) \propto R(NLR,1)^{0.88 +/-
0.1}. This relation can be used to estimate BH masses.


title: The Spin History of Protostars: Disk Locking, Revisited

abstract:
  In this talk, we take a new look at the theory of disk locking, which assumes
that an accreting protostar rids itself of accreted angular momentum through a
magnetic coupling with the accretion disk. We consider that differential
rotation between the star and disk twists the field lines. For large enough
twist, the magnetic field lines connecting the star and disk open and
disconnect. This significantly reduces the spin-down torque on the star by the
disk, and so we find that disk-locking theory predicts spin periods that are
much too short to account for typical observed systems.


title:
A deep survey of heavy element lines in planetary nebulae -- II.
  Recombination line abundances and evidence for ultra-cold plasma

abstract:
  [Abridged] Deep optical observations of the spectra of 12 Galactic planetary
nebulae (PNe) and 3 Magellanic Cloud PNe were presented in Paper I by Tsamis et
al. (2003b), who carried out an abundance analysis using the collisionally
excited forbidden lines. Here, the relative intensities of faint optical
recombination lines (ORLs) from ions of carbon, nitrogen and oxygen are
analysed in order to derive the abundances of these ions relative to hydrogen.
We define an abundance discrepancy factor (ADF) as the ratio of the abundance
derived for a heavy element ion from its recombination lines to that derived
for the same ion from its ultraviolet, optical or infrared collisionally
excited lines (CELs). All of the PNe in our sample are found to have ADF's that
exceed unity. There is no dependence of the magnitude of the ADF upon the
excitation energy of the UV, optical or IR CEL transition used, indicating that
classical nebular temperature fluctuations--i.e. in a chemically homogeneous
medium--are not the cause of the observed abundance discrepancies. Instead, we
conclude that the main cause of the discrepancy is enhanced ORL emission from
cold ionized gas located in hydrogen-deficient clumps inside the main body of
the nebulae. We have developed a new electron temperature diagnostic, based
upon the relative intensities of the OII 4f-3d 4089A and 3p-3s 4649A
recombination transitions. For six out of eight PNe for which both transitions
are detected, we derive O2+ ORL electron temperatures of <300 K, very much less
than the O2+ forbidden-line and Balmer jump temperatures derived for the same
nebulae. These results provide direct observational evidence for the presence
of H-deficient, cold plasma regions within the nebulae, consistent with gas
cooled largely by infrared fine structure and recombination transitions.


title:
Winds driven by super-star clusters: The self-consistent radiative
  solution

abstract:
  Here we present a self-consistent stationary solution for spherically
symmetric winds driven by massive star clusters under the impact of radiative
cooling. We demonstrate that cooling may modify drastically the distribution of
temperature if the rate of injected energy approaches a critical value. We also
prove that the stationary wind solution does not exist whenever the energy
radiated away at the star cluster center exceeds ~ 30% of the energy deposition
rate. Finally we thoroughly discuss the expected appearance of super-star
cluster winds in the X-ray and visible line regimes. The three solutions here
found: the quasi-adiabatic, the strongly radiative wind and the inhibited
stationary solution, are then compared to the winds from Arches cluster, NGC
4303 central cluster and to the supernebula in NGC 5253.


title: Constraints on Non-Standard Recombination from Recent CMB Observations

abstract:
  We examine cosmic microwave background constraints on variations in the
recombination history of the universe. We use a very general extension to the
standard model of recombination characterized by two parameters, a and b, which
multiply the overall rates of recombination and ionization and the binding
energies of hydrogen respectively. We utilize WMAP temperature and TE
cross-correlation data, along with temperature data at smaller scales from
ACBAR and CBI, to place constraints on these parameters. The range of
recombination histories which gives the best fit to the data is -0.6 < log(a) <
0.5 and 0.85 < b < 1.15, forming a diagonal region from low-a/high-b to
high-a/low-b. We find z_rec = 1055 +- 25 and \delta z = 198 +- 5 at 68%
confidence for the range of recombination models which are best able to
reproduce the observed CMB power spectra. Standard recombination provides an
acceptable fit to the data; while there is still room for non-standard
recombination, the allowed variation is small.


title: Spectral index maps of the radio halos in Abell 665 and Abell 2163

abstract:
  New radio data at 330 MHz are presented for the rich clusters Abell 665 and
Abell 2163, whose radio emission is characterized by the presence of a radio
halo. These images allowed us to derive the spectral properties of the two
clusters under study. The integrated spectra of these halos between 0.3 GHz and
1.4 GHz are moderately steep: alfa(0.3-1.4) = 1.04 and = 1.18, for A665 and
A2163, respectively. The spectral index maps, produced with an angular
resolution of the order of 1 arcmin, show features of the spectral index
(flattening and patches), which are indication of a complex shape of the
radiating electron spectrum, and are therefore in support of electron
reacceleration models. Regions of flatter spectrum are found to be related to
the recent merger activity in these clusters. This is the first strong
confirmation that the cluster merger supplies energy to the radio halo. In the
undisturbed cluster regions, the spectrum steepens with the distance from the
cluster center. This is interpreted as the result of the combination of the
magnetic field profile with the spatial distribution of the reacceleration
efficiency, thus allowing us to set constraints on the radial profile of the
cluster magnetic field.


title: The V_c-sigma_c relation in high and low surface brightness galaxies

abstract:
  We investigate the relation between the asymptotic circular velocity, V_c,
and the central stellar velocity dispersion, sigma_c, in galaxies. We consider
a new sample of high surface brightness spiral galaxies (HSB), low surface
brightness spiral galaxies (LSB), and elliptical galaxies with HI-based V_c
measurements. We find that: 1) elliptical galaxies with HI measurements fit
well within the relation; 2) a linear law can reproduce the data as well as a
power law (used in previous works) even for galaxies with sigma_c < 70 km/s; 3)
LSB galaxies, considered for the first time with this respect, seem to behave
differently, showing either larger V_c values or smaller sigma_c values.


title: Resolving the Nature of the LMC Microlensing Event LMC-5

abstract:
  We present the results from an analysis of Hubble Space Telescope High
Resolution Camera data for the Large Magellanic Cloud microlensing event
MACHO-LMC-5. By determining the parallax and proper motion of this object we
find that the lens is an M dwarf star at a distance of 578(+65/-53)pc with a
proper motion of 21.39 +/- 0.04 mas/yr. Based on the kinematics and location of
this star it more likely to be part of the Galactic thick disk than thin disk
population. We confirm that the microlensing event LMC-5 is a jerk-parallax
event.


title: The stellar content of the ring in NGC 660

abstract:
  We present the results of stellar photometry of the polar-ring galaxy NGC 660
using the Hubble Space Telescope's archival data obtained with the Wide Field
Planetary Camera 2. The final list of the resolved stars contains 550 objects,
a considerable part of which are blue and red supergiants belonging to the
polar ring. The analysis of the Colour Magnitude Diagram for polar ring stars
shows that it is best represented by the isochrones with metallicity Z = 0.008.
The process of star formation in the polar ring was continuous and the age of
the youngest detected stars is about 7 Myr.


title:
The Low Quiescent X-Ray Luminosity of the Neutron Star Transient XTE
  J2123-058

abstract:
  We report on the first X-ray observations of the neutron star soft X-ray
transient (SXT) XTE J2123-058 in quiescence, made by Chandra and BeppoSAX, as
well as contemporaneous optical observations. In 2002, the Chandra spectrum of
XTE J2123-058 is consistent with a power-law model, or the combination of a
blackbody plus a power-law, but it is not well-described by a pure blackbody.
Using the interstellar column density, the power-law fit gives photon index of
3.1 (+0.7,-0.6) and indicates a 0.3-8 keV unabsorbed luminosity of 9(+4,-3)E31
(d/8.5 kpc)^2 ergs/s (90% confidence errors). Fits with models consisting of
thermal plus power-law components indicate that the upper limit on the
temperature of a 1.4 solar mass, 10 km radius neutron star with a hydrogen
atmosphere is kT_eff < 66 eV, and the upper limit on the bolometric luminosity
is L_infinity < 1.4E32 ergs/s, assuming d = 8.5 kpc. Of the neutron star SXTs
that exhibit short (< 1 year) outbursts, including Aql X-1, 4U 1608-522, Cen
X-4, and SAX J1810.8-2609, the lowest temperatures and luminosities are found
for XTE J2123-058 and SAX J1810.8-2609. From the BeppoSAX observation of XTE
J2123-058 in 2000, we obtained an upper limit on the 1-10 keV unabsorbed
luminosity of 9E32 ergs/s. Although this upper limit allows that the X-ray
luminosity may have decreased between 2000 and 2002, that possibility is not
supported by our contemporaneous R-band observations, which indicate that the
optical flux increased significantly. Motivated by the theory of deep crustal
heating by Brown and co-workers, we characterize the outburst histories of the
five SXTs. The low quiescent luminosity for XTE J2123-058 is consistent with
the theory of deep crustal heating without requiring enhanced neutron star
cooling if the outburst recurrence time is >~ 70 years.


title:
Rate Coefficient for H^+ + H_2(X ^1Sigma_g^+, nu=0, J=0) --> H(1s) +
  H_2^+ Charge Transfer and Some Cosmological Implications

abstract:
  Krstic has carried out the first quantum mechanical calculations near
threshold for the charge transfer (CT) process H^+ + H_2(X ^1Sigma_g^+, nu=0,
J=0) --> H(1s) + H_2^+. These results are relevant for models of primordial
galaxy and first star formation that require reliable atomic and molecular data
for obtaining the early universe hydrogen chemistry. Using the results of
Krstic, we calculate the relevant CT rate coefficient for temperatures between
100 and 30,000 K. We also present a simple fit which can be readily implemented
into early universe chemical models. Additionally, we explore how the range of
previously published data for this reaction translates into uncertainties in
the predicted gas temperature and H_2 relative abundance in a collapsing
primordial gas cloud. Our new data significantly reduce these cosmological
uncertainties that are due to the uncertainties in the previously published CT
rate coefficients.


title:
Chandra Observation of V426 Oph: Weighing the Evidence for a Magnetic
  White Dwarf

abstract:
  We report the results of a 45 ks Chandra observation of the cataclysmic
variable V426 Ophiuchus. The high resolution spectrum from the high-energy
transmission grating spectrometer is most consistent with a cooling flow model,
placing V426 Oph among the group of CVs including U Gem and EX Hya. An
uninterrupted lightcurve was also constructed, in which we detect a significant
4.2 hr modulation together with its first harmonic at 2.1 hrs. Reanalysis of
archival Ginga, and ROSAT X-ray lightcurves also reveals modulations at periods
consistent with 4.2 and/or 2.1 hrs. Furthermore, optical photometry in V,
simultaneous with the Chandra observation, indicates a modulation
anti-correlated with the X-ray, and later more extensive R band photometry
finds a signal at ~2.1 hrs. The earlier reported X-ray periods at ~0.5 and 1
hrs appear to be only transient and quasi-periodic in nature. In contrast, the
4.2 hr period or its harmonic are stable and persistent in X-ray/optical data
from 1988 to 2003. This periodicity is clearly distinct from the 6.85 hr orbit,
and could be due to the spin of the white dwarf. If this is the case, V426 Oph
would be the first long period intermediate polar with a ratio P_spin/P_orb of
0.6. However, this interpretation requires unreasonable values of magnetic
field strength and mass accretion rate.


title: A hydrogenic molecular atmosphere of a neutron star

abstract:
  A model of a hydrogenic content of atmosphere of the isolated neutron star
1E1207.4-5209 is proposed. It is based on the assumption that the main
component in the atmosphere is the exotic molecular ion $H_3^{2+}$ and that
there exists a magnetic field in the range of $(4 \pm 2) \times 10^{14}$ G.
Photoionization $H_3^{2+} \rar e + 3p$ and photodissociation $H_3^{2+} \rar H +
2p$ correspond to two absorption features at 0.7 KeV and 1.4 KeV, respectively,
discovered by {\it Chandra} observatory (Sanwal et al, 2002). The model
predicts one more absorption feature at 80-150 eV corresponding to
photodissociation $H_3^{2+} \rar H_2^+ + p$.


title: A Helium White Dwarf of Extremely Low Mass

abstract:
  We analyze the spectrum of an unusually-low mass white dwarf,
SDSSJ123410.37-022802.9 (0335-264-52000), found in our recent, white dwarf
catalog from the SDSS DR1 data release. Two independent, model atmosphere fits
result in an accurate determination of atmospheric and stellar parameters. The
more hands-on analysis yields $T_{\rm eff}$ =17,470$\pm$750 K and $\log g$ =
6.38$\pm$0.05. We argue that the object cannot be a main sequence A star, a
horizontal branch or subdwarf B star. Instead, it is interpreted as a very low
mass white dwarf with a core composed of helium, with mass
($\sim$0.18-0.19$M_\odot$), similar to that published previously for the
unusual companion to the millisecond pulsar J1012+5307. The star probably
remains in a binary, perhaps even with an undiscovered or dead pulsar
companion. However, the companion might be a more-ordinary star, provided Roche
lobe mass transfer began shortly after the now-visible component left the main
sequence. A second SDSS low mass white dwarf candidate is also analyzed, but
the spectrum for this fainter object is of poorer quality. The sample appears
to include additional, similar candidates, worthy of more accurate observation.
Correct identification of any additional white dwarfs of extremely low mass
requires careful observation and interpretation.


title:
The Spectroscopically Determined Substellar Mass Function of the Orion
  Nebula Cluster

abstract:
  We present a spectroscopic study of candidate brown dwarf members of the
Orion Nebula Cluster (ONC). We obtained new J- and/or K-band spectra of ~100
objects within the ONC which are expected to be substellar based on their
K,(H-K) magnitudes and colors. Spectral classification in the near-infrared of
young low mass objects is described, including the effects of surface gravity,
veiling due to circumstellar material, and reddening. From our derived spectral
types and existing near-infrared photometry we construct an HR diagram for the
cluster. Masses are inferred for each object and used to derive the brown dwarf
fraction and assess the mass function for the inner 5.'1 x 5.'1 of the ONC,
down to ~0.02 solar masses. The derived logarithmic mass function rises to a
peak at ~0.2 solar masses, similar to previous IMF determinations derived from
purely photometric methods, but falls off more sharply at the hydrogen-burning
limit before leveling through the substellar regime. We compare the mass
function derived here for the inner ONC to those presented in recent literature
for the sparsely populated Taurus cloud members and the rich cluster IC 348. We
find good agreement between the shapes and peak values of the ONC and IC 348
mass distributions, but little similarity between the ONC and Taurus results.


title:
Roles of Supernova Ejecta in Nucleosynthesis of Light Elements, Li, Be,
  and B

abstract:
  Explosions of type Ic supernovae (SNe Ic) are investigated using a
relativistic hydrodynamic code to study roles of their outermost layers of the
ejecta in light element nucleosynthesis through spallation reactions as a
possible mechanism of the "primary" process. We have confirmed that the energy
distribution of the outermost layers with a mass fraction of only 0.001 %
follows the empirical formula proposed by previous work when the explosion is
furious. In such explosions, a significant fraction of the ejecta ($>$0.1 % in
mass) have the energy greater than the threshold energy for spallation
reactions. On the other hand, it is found that the outermost layers of ejecta
become more energetic than the empirical formula would predict when the
explosion energy per unit ejecta mass is smaller than $\sim 1.3\times
10^{51}{ergs/}\Msun$. As a consequence, it is necessary to numerically
calculate explosions to estimate light element yields from SNe Ic. The usage of
the empirical formula would overestimate the yields by a factor of $\gtsim 3$
for energetic explosions such as SN 1998bw and underestimate the yields by a
similar factor for less energetic explosions like SN 1994I. The yields of light
elements Li, Be, and B (LiBeB) from SNe Ic are estimated by solving the
transfer equation of cosmic rays originated from ejecta of SNe Ic and compared
with observations.


title:
Disappearance of N2H+ from the Gas Phase in the Class 0 Protostar IRAM
  04191

abstract:
  We present a high-resolution millimeter study of the very young Class 0
protostar IRAM 04191+1522 in the Taurus molecular cloud. N2H+(1-0) observations
with the IRAM Plateau de Bure Interferometer and 30m telescope demonstrate that
the molecular ion N2H+ disappears from the gas phase in the inner part of the
protostellar envelope (r < 1600 AU, n(H2) > 5 x 10^5 cm^-3). This result
departs from the predictions of current chemical models. It suggests either
that N2 is more depleted than the models predict, owing to a higher binding
energy on polar ice or an enhanced grain chemistry transforming N2 to less
volatile species, or that strong deuterium fractionation enhances N2D+ to the
detriment of N2H+.


title:
High resolution imaging of the radio continuum and neutral gas in the
  inner kiloparsec of the radio galaxy 3C293

abstract:
  Using a combination of observations involving the VLA, MERLIN and global VLBI
networks we have made a detailed study of the radio continuum and the neutral
hydrogen (HI) kinematics and distribution within the central kiloparsec of the
radio galaxy 3C293. These observations trace the complex jet structure and
identify the position of the steeply inverted radio core at 1.3GHz.
  Strong HI absorption is detected against the majority of the inner kiloparsec
of 3C293. This absorption is separated into two dynamically different and
spatially resolved systems. Against the eastern part of the inner radio jet
narrow HI absorption is detected and shown to have higher optical depths in
areas co-spatial with a central dust lane. Against the western jet emission and
core component, broad and complex HI absorption is detected. This broad and
complex absorption structure is discussed in terms of two possible
interpretations for the gas kinematics observed: that the gas is situated in
two gas layers or that it is in a sub-kiloparsec disk rotating about the core.
(Abridged)


title: Is the slope of the intrinsic Baldwin effect constant?

abstract:
  We investigate the relationship between emission-line strength and continuum
luminosity in the best-studied nearby Seyfert 1 galaxy NGC5548. Our analysis of
13 years of ground-based optical monitoring data reveals significant
year-to-year variations in the observed H-beta emission-line response in this
source. More specifically, we confirm the result of Gilbert and Peterson (2003)
of a non-linear relationship between the continuum and H-beta emission-line
fluxes. Furthermore, we show that the slope of this relation is not constant,
but rather decreases as the continuum flux increases. Both effects are
consistent with photoionisation model predictions of a luminosity-dependent
response in this line.


title: Star Formation and Dynamics in the nuclei of AGN

abstract:
  Using adaptive optics on Keck and the VLT in the H- and K-bands, we have
begun a project to probe the dynamics and star formation around AGN on scales
of 0.1arcsec. The stellar content of the nucleus is traced through the
2.29micron CO2-0 and 1.62micron CO6-3 absorption bandheads. These features are
directly spatially resolved, allowing us to measure the extent and distribution
of the nuclear star forming region. The dynamics are traced through the
2.12micron H_2 1-0S(1) and 1.64micron [FeII] emission lines, as well as stellar
absorption features. Matching disk models to the rotation curves at various
position angles allows us to determine the mass of the stellar and gas
components, and constrain the mass of the central black hole. In this
contribution we summarise results for the two type~1 AGN Mkn231 and NGC7469.


title:
Iron abundances from high-resolution spectroscopy of the open clusters
  NGC 2506, NGC 6134, and IC 4651

abstract:
  This is the first of a series of papers devoted to derive the metallicity of
old open clusters in order to study the time evolution of the chemical
abundance gradient in the Galactic disk. We present detailed iron abundances
from high resolution (R~40000) spectra of several red clump and bright giant
stars in the open clusters IC 4651, NGC 2506 and NGC 6134. We observed 4 stars
of NGC 2506, 3 stars of NGC 6134, and 5 stars of IC 4651 with the FEROS
spectrograph at the ESO 1.5 m telescope; moreover, 3 other stars of NGC 6134
were observed with the UVES spectrograph on Kueyen (VLT UT2). After excluding
the cool giants near the red giant branch tip (one in IC 4651 and one in NGC
2506), we found overall [Fe/H] values of -0.20 +/- 0.01, rms = 0.02 dex (2
stars) for NGC 2506, +0.15 +/- 0.03, rms = 0.07 dex (6 stars) for NGC 6134, and
+0.11 +/- 0.01, rms = 0.01 dex (4 stars) for IC 4651. The metal abundances
derived from line analysis for each star were extensively checked using
spectrum synthesis of about 30 to 40 Fe I lines and 6 Fe II lines. Our
spectroscopic temperatures provide reddening values in good agreement with
literature data for these clusters, strengthening the reliability of the
adopted temperature and metallicity scale. Also, gravities from the Fe
equilibrium of ionization agree quite well with expectations based on cluster
distance moduli and evolutionary masses.


title: Brane Universes Tested by Supernovae Ia

abstract:
  We discuss observational constrains coming from supernovae Ia imposed on the
behaviour of the Randall-Sundrum models. In the case of dust matter on the
brane, the difference between the best-fit Perlmutter model with a
$\Lambda$-term and the best-fit brane models becomes detectable for redshifts
$z > 1.2$. It is interesting that brane models predict brighter galaxies for
such redshifts which is in agreement with the measurement of the $z = 1.7$
supernova. We also demonstrate that the fit to supernovae data can also be
obtained, if we admit the "super-negative" dark energy (phantom matter) $p= -
(4/3) \varrho$ on the brane, where the dark energy in a way mimics the
influence of the cosmological constant. It also appears that the dark energy
enlarges the age of the universe which is demanded in cosmology. Finally, we
propose to check for dark radiation and brane tension by the application of the
angular diameter of galaxies minimum value test. We point out the existence of
coincidence problem for the brane tension parameter.


title:
High mass X-ray binaries in the LMC: dependence on the stellar
  population age and the "propeller" effect

abstract:
  We study population of compact X-ray sources in the Large Magellanic Cloud
using the archival data of XMM-Newton observatory. The total area of the survey
is approximately 3.8 square degrees with the limiting sensitivity of about
10^{-14} erg/s/cm^2, corresponding to the luminosity of 3*10^{33} erg/s at the
LMC distance. Out of 460 point sources detected in the 2--8 keV energy band,the
vast majority are background CXB sources, observed through LMC. Based on the
properties of the optical and near-infrared counterparts of the detected
sources we identified 9 likely HMXB candidates, and 19 sources, which nature is
uncertain, thus, providing a lower and upper limits on the luminosity
distribution of HMXBs in the observed part of LMC. When considered globally,
the bright end of this distribution is consistent within statistical and
systematic uncertainties with extrapolation of the universal luminosity
function of HMXBs. However, there seems to be fewer low luminosity sources,
log(Lx)<35.5, than predicted. We consider the impact of the ``propeller
effect'' on the HMXB luminosity distribution and show, that it can
qualitatively explain the observed deficit of low luminosity sources. We found
significant field-to-field variations in the number of HMXBs across the LMC,
which appear to be uncorrelated with the star formation rates inferred by the
FIR and Halpha emission. We suggest that these variations are caused by the
dependence of the HMXB number on the age of the underlying stellar population.
Using the existence of large coeval stellar aggregates in the LMC, we constrain
the number of HMXBs as a function of time elapsed since the star formation
event in the range of from 1-2 Myr to 10-12 Myr.


title:
The role of dust in "active" and "passive" low-metallicity star
  formation

abstract:
  We investigate the role of dust in star formation activity of extremely
metal-poor blue compact dwarf galaxies (BCDs). Observations suggest that star
formation in BCDs occurs in two different regimes: "active" and "passive". The
"active" BCDs host super star clusters (SSCs), and are characterised by compact
size, rich H2 content, large dust optical depth, and high dust temperature; the
"passive" BCDs are more diffuse with cooler dust, and lack SSCs and large
amounts of H2. By treating physical processes concerning formation of stars and
dust, we are able to simultaneously reproduce all the above properties of both
modes of star formation (active and passive). We find that the difference
between the two regimes can be understood through the variation of the
"compactness" of the star-forming region: an "active" mode emerges if the
region is compact (with radius $\la 50$ pc) and dense (with gas number density
$\ga 500$ cm$^{-3}$). The dust, supplied from Type II supernovae in a compact
star-forming region, effectively reprocesses the heating photons into the
infrared and induces a rapid H2 formation over a period of several Myr. This
explains the high infrared luminosity, high dust temperature, and large H2
content of active BCDs. Moreover, the gas in "active" galaxies cools ($\la 300$
K) on a few dynamical timescales, producing a "run-away" star formation episode
because of the favourable (cool) conditions. The mild extinction and relatively
low molecular content of passive BCDs can also be explained by the same model
if we assume a diffuse region (with radius $\ga 100$ pc and gas number density
$\la 100$ cm$^{-3}$). We finally discuss primordial star formation in
high-redshift galaxies in the context of the "active" and "passive" star
formation scenario.


title:
The roles of ram-pressure stripping and minor mergers in evolution of
  galaxies

abstract:
  We investigate environmental effects on evolution of bright cluster galaxies
in a Lambda-dominated cold dark matter universe using a combination of
dissipationless N-body simulations and a semi-analytic galaxy formation model.
We incorporate effects of ram-pressure stripping (RPS) and minor merger-induced
small starburst (minor burst) into our model. By considering minor burst,
observed morphology-radius relation is successfully reproduced. When we do not
consider minor burst, the RPS hardly increases the intermediate B/T population.
In addition, the RPS and minor burst are not important for colours or star
formation rates of galaxies in the cluster core if star formation time-scale is
properly chosen, because the star formation is sufficiently suppressed by
consumption of the cold gas. We also find that SF in bulge-dominated galaxies
is mainly terminated by starburst induced by major mergers in all environments.


title: To accrete or not to accrete: the dilemma of the recycling scenario

abstract:
  We study the evolution of a low-mass X-ray binary by coupling a binary
stellar evolution code with a general relativistic code that describes the
behaviour of the neutron star. We find that non-conservative mass transfer
scenarios are required to prevent the formation of submillisecond pulsars
and/or the collapse to a black hole. We discuss the sweeping effects of an
active magneto-dipole rotator on the transferred matter as a promising
mechanism to obtain highly non-conservative evolutions.


title:
Statistics of cluster multiplicity and the nature of UHE cosmic ray
  sources

abstract:
  We study in detail the properties of clusters of ultra high energy cosmic ray
events, looking in particular to their angular correlation function, to the
relative frequency of clusters with different multiplicities (e.g. doublets vs.
triplets or quadruplets), as well as the way in which these quantities should
evolve for different ultra high energy cosmic rays source scenarios as a
function of the experimental exposure achieved. We identify some useful tools
which can help to characterise the nature of the cosmic ray sources in a more
precise way after a modest increase in statistics will be achieved in the very
near future, even before strong signals from individual sources become
eventually observable.


title: Reionisation: the role of Globular Clusters

abstract:
  In this talk I discuss the role of proto-globular clusters as the dominant
sources of radiation that reionised hydrogen in the intergalactic medium (IGM)
at redshift z~6. Observations at lower redshifts indicate that only a small
fraction, f_esc, of hydrogen ionising radiation emitted from massive stars can
escape unabsorbed by the galaxy into the IGM. High redshift galaxies are
expected to be more compact and gas rich than present day galaxies,
consequently f_esc from their disks or spheroids might have been very small.
But if the sites of star formation in the galaxies are off-centre and if the
star formation efficiency of the proto-clusters is high, then the mean f_esc
calculated for these objects only, is expected to be close to unity.
  Here I argue that this mode of star formation is consistent with several
models for globular clusters formation. Using simple arguments based on the
observed number of globular cluster systems in the local universe and assuming
that the oldest globular clusters formed before reionisation and had f_esc~1, I
show that they produced enough ionising photons to reionise the IGM at z~6. I
also enphasize that globular cluster formation might have been the dominant
mode of star formation at redshifts from 6 to 12.


title: Mid-infrared selection of AGN

abstract:
  Since a large fraction of active galactic nuclei (AGN) is missed in common
UV-excess surveys and is even hard to find in radio, near-IR and X-ray surveys,
we have used a new AGN selection technique which is expected to be not affected
by extinction. Within the scientific verification of the ISOCAM Parallel Survey
at 6.7 micron we have discovered objects with exceptional mid-infrared (MIR)
emission. They are essentially not detected on IRAS-ADDSCANs and only very few
of them show up in the NVSS and FIRST radio surveys. Various colour criteria of
the 6.7 micron data with 2MASS and optical wavebands show that the sources
reach more extreme IR colours than the sources in the Hubble Deep Field-South
and the ELAIS survey. The comparison with known object types suggests that we
have found AGN with a pronounced MIR emission, probably due to circum-nuclear
dust. First results from optical spectroscopy of ten candidates corroborate
this interpretation showing four AGN, two reddened LINER and four extremely
reddened emission-line galaxies with MIR/FIR flux ratios higher than for known
pure starburst galaxies. The results will make a significant contribution to
the debate on the entire AGN population.


title:
The Contribution of Different Supernova Populations to the Galactic
  Gamma-Ray Background

abstract:
  The contribution of Source Cosmic Rays (SCRs), accelerated and still confined
in Supernova Remnants (SNRs), to the diffuse high energy \gr emission above 1
GeV from the Galactic disk is studied. The \grs produced by the SCRs have a
much harder spectrum than those generated by the Galactic Cosmic Rays (GCRs).
Extending a previous paper, a simple SNR population synthesis is considered and
the Inverse Compton emission from the SCR electrons is evaluated in greater
detail. Then the combined spectrum of \gr emission from the Galactic Supernova
Remnant population is calculated and this emission at low Galactic latitudes is
compared with the diffuse \gr emission observed by the EGRET and ground based
instruments. The average contribution of SCRs is comparable to the GCR
contribution already at GeV energies, due to Supernovae of types II and Ib
exploding into the wind bubbles of quite massive progenitor stars, and becomes
dominant at \gr energies above 100 GeV. At TeV energies the dominant
contribution is from SCRs in SNRs that expand into a uniform interstellar
medium. In fact, the sum of hadronic and Inverse Compton \grs would exceed the
limits given by the existing experimental data, unless the confinement time
$T_{SN}$, i.e. the time until which SNRs confine the main fraction of
accelerated SCRs, is as small as $T_{SN}\sim 10^4$ yr and the typical magnetic
field strength in SNRs as large as 30 $\mu$G. Both situations are however
possible as a result of field amplification through CR backreaction in the
acceleration process. It is pointed out that accurate measurements of the
low-latitude diffuse Galactic \gr spectrum at TeV-energies can serve as a
unique consistency test for CR origin from the Supernova Remnant population as
a whole.


title:
X-ray reprocessing in Seyfert Galaxies: simultaneous XMM-Newton/BeppoSAX
  observations

abstract:
  We selected a sample of eight bright unobscured (at least at the iron line
energy) Seyfert Galaxies observed simultaneously by XMM-Newton and BeppoSAX,
taking advantage of the complementary characteristics of the two missions. The
main results of our analysis can be summarized as follows: narrow neutral iron
lines are confirmed to be an ubiquitous component in Seyfert spectra; none of
the analyzed sources shows unambiguously a broad relativistic iron line; all
the sources of our sample (with a single exception) show the presence of a
Compton reflection component; emission lines from ionized iron are observed in
some sources; peculiar weak features around 5-6 keV (possibly arising from
rotating spots on the accretion disk) are detected in two sources. The scenario
emerging from these results strongly requires some corrections for the
classical model of reprocessing from the accretion disk. As for materials
farther away from the Black Hole, our results represent a positive test for the
Unification Model, suggesting the presence of the torus in (almost) all
sources, even if unobscured.


title: OGLE 2003-BLG-235/MOA 2003-BLG-53: A planetary microlensing event

abstract:
  We present observations of the unusual microlensing event OGLE
2003-BLG-235/MOA 2003-BLG-53. In this event a short duration (~7 days) low
amplitude deviation in the light curve due a single lens profile was observed
in both the MOA and OGLE survey observations. We find that the observed
features of the light curve can only be reproduced using a binary microlensing
model with an extreme (planetary) mass ratio of 0.0039 +/- (11, 07) for the
lensing system. If the lens system comprises a main sequence primary, we infer
that the secondary is a planet of about 1.5 Jupiter masses with an orbital
radius of ~3 AU.


title:
ISOPHOT 95 micron observations in the Lockman Hole - The catalogue and
  an assessment of the source counts

abstract:
  We report results from a new analysis of a deep 95 micron imaging survey with
ISOPHOT on board the Infrared Space Observatory, over a ~1 square degree area
within the Lockman Hole, which extends the statistics of our previous study
(Rodighiero et al. 2003). Within the survey area we detect sixty-four sources
with S/N>3 (roughly corresponding to a flux limit of 16 mJy). Extensive
simulations indicate that the sample is almost complete at fluxes > 100 mJy,
while the incompleteness can be quantified down to ~30 mJy. The 95 micron
galaxy counts reveal a steep slope below 100 mJy (alpha~1.6), in excess of that
expected for a non-evolving source population. In agreement with counts data
from ISO at 15 and 175 micron, this favours a model where the IR populations
evolve both in number and luminosity densities. We finally comment on some
differences found with other ISO results in this area.


title: First results with the ORPHEUS dark matter detector

abstract:
  The ORPHEUS dark matter detector is operating at our underground laboratory
in Bern (70 m.w.e.). The detector relies on measuring the magnetic flux
variation produced by weakly interacting massive particles (WIMPs) as they heat
micron-sized superheated superconducting tin granules (SSG) and induce
superconducting-to-normal phase transitions. In an initial phase, 0.45 kg of
tin granules in a segmented detector volume have been used. In this paper a
general description of the experimental set-up, overall performance of the
detector, and first results are presented.


title:
X-ray, Radio, and Optical Observations of the Putative Pulsar in the
  Supernova Remnant CTA 1

abstract:
  A Chandra image of the central X-ray source RX J0007.0+7303 in the supernova
remnant CTA 1 reveals a point source, a compact nebula, and a bent jet, all of
which are characteristic of energetic, rotation-powered pulsars. Using the MDM
2.4m telescope we obtain upper limits in the optical at the position of the
point source, (J2000) 00h07m01.56s, +73o03'08.1", determined to an accuracy of
0.1", of B>25.4, V>24.8, R>25.1, and I>23.7; these correspond to an
X-ray-to-optical flux ratio >100. Neither a VLA image at 1425 MHz, nor a deep
pulsar search at 820 MHz using the NRAO Green Bank Telescope, reveal a radio
pulsar counterpart to an equivalent luminosity limit at 1400 MHz of 0.02 mJy
kpc^2, which is equal to the lowest luminosity known for any radio pulsar. The
Chandra point source accounts for about 30% of the flux of RX J0007.0+7303,
while its compact nebula plus jet comprise about 70%. The X-ray spectrum of the
point source is fitted with a power-law plus blackbody model with Gamma =
1.6+/-0.6, kT_{infty} = 0.13+/-0.05 keV, and R_infty = 0.37 km, values typical
of a young pulsar. An upper limit of T^{infty}_e < 6.6x10^5 K to the effective
temperature of the entire neutron star surface is derived, which is one of the
most constraining data points on cooling models. The 0.5-10 keV luminosity of
RX J0007.0+7303 is 4x10^{31}(d/1.4 kpc)^2 ergs s^{-1}, but the larger ~18'
diameter synchrotron nebula in which it is embedded is two orders of magnitude
more luminous. These properties allow us to estimate, albeit crudely, that the
spin-down luminosity of the underlying pulsar is in the range 10^{36}-10^{37}
ergs s^{-1}, and support the identification of the high-energy gamma-ray source
3EG J0010+7309 as a pulsar even though its spin parameters have not yet been
determined.


title:
Galaxy Cluster Formation from the Large-scale Structure: A Case Study of
  the Abell 2125 Complex at z=0.247

abstract:
  The structure of the universe is believed to have formed by clustering
hierarchically from small to large scales. Much of this evolution occurs very
slowly but at a few special times more, rapid, violent activity may occur as
major subunits collide at high velocities. The Abell 2125 complex (z=0.247)
appears to be undergoing such an event as shown by modeling of the optical
velocity field and by the detection with the VLA of an unusually large number
of associated radio active galaxies. We present an 80 ksec Chandra imaging of
Abell 2125, together with extensive complementary multi-wavelength data. We
show direct evidence for galaxy transformation and destruction during the
cluster formation. The Chandra data unambiguously separate the X-ray
contributions from discrete sources and large-scale diffuse gas in the Abell
2125 complex, which consists of various merging clusters/groups of galaxies and
low-surface brightness emission. This enables us to study processes affecting
galaxy evolution during this special time from scales of Mpc down to a few kpc.
The overall level of activity plus the special time for the cluster-cluster
merger suggests that an important phase of galaxy evolution can take place
during such events.


title: Dynamical Masses of RCS Galaxy Clusters

abstract:
  A multi-object spectroscopy follow-up survey of galaxy clusters selected from
the Red-sequence Cluster Survey (RCS) is being completed. About forty clusters
were chosen with redshifts from 0.15 to 0.6, and in a wide range of richnesses.
One of the main science drivers of this survey is a study of internal dynamics
of clusters. We present some preliminary results for a subset of the clusters,
including the correlation of optical richness with mass, and the mass-to-light
ratio as a function of cluster mass.


title:
Final Analysis of ELAIS 15 $\mu$m Observations : Method, Reduction and
  Catalogue

abstract:
  We present the Final Analysis of the European Large Area ISO Survey (ELAIS)
15 $\mu$m observations, carried out with the ISOCAM instrument on board the
Infrared Space Observatory (ISO).
  The data reduction method, known as LARI method, is based on a mathematical
model of the detector's behaviour and was specifically designed for the
detection of faint sources in ISO-CAM/PHOT data. The method is fully
interactive and leads to very reliable and complete source lists.
  The resulting catalogue includes 1923 sources detected with $S/N > 5$ in the
{0.5 -- 100 mJy} flux range and over an area of 10.85 {deg$^2$} split into four
fields, making it the largest non-serendipitous extragalactic source catalogue
obtained to date from ISO data.
  This paper presents the concepts underlying the data reduction method
together with its latest enhancements. The data reduction process, the
production and basic properties of the resulting catalogue are discussed. The
catalogue quality is assessed by means of detailed simulations, optical
identifications and comparison with previous analyses.


title:
Winds from Nuclear Starbursts: Old Truths and Recent Progress on
  Superwinds

abstract:
  I will discuss a few select aspects of the most common and best understood
galactic-scale outflow -- starburst-driven superwinds, focusing on winds from
nuclear starburst galaxies. I will show that modern observations, in particular
in the soft and hard X-ray bands, complement and reinforce the existing
paradigm of superwinds as flows collectively driven by multiple SNe. The
properties of the diffuse X-ray emission from dwarf starburst galaxies, L_BOL ~
L_* starbursts in spiral galaxies, and ULIRGS, are all consistent with
superwind activity. Where appropriate, I contrast the physics of
starburst-driven winds with poorly collimated winds from AGN, and discuss what
we know of the role of LLAGN and Seyfert nuclei in starburst superwind
galaxies.


title:
Joint cosmological parameters forecast from CFHTLS-cosmic shear and CMB
  data

abstract:
  We present a prospective analysis of a combined cosmic shear and cosmic
microwave background data set, focusing on a Canada France Hawaii Telescope
Legacy Survey (CFHTLS) type lensing survey and the current WMAP-1 year and CBI
data. We investigate the parameter degeneracies and error estimates of a seven
parameters model, for the lensing alone as well as for the combined
experiments. The analysis is performed using a Monte Carlo Markov Chain
calculation, allowing for a more realistic estimate of errors and degeneracies
than a Fisher matrix approach. After a detailed discussion of the relevant
statistical techniques, the set of the most relevant 2 and 3-dimensional
lensing contours are given. It is shown that the combined cosmic shear and CMB
is particularly efficient to break some parameter degeneracies. The principal
components directions are computed and it is found that the most orthogonal
contours between the two experiments are for the parameter pairs
(Omega_m,sigma_8), (h,ns) and (ns,nrun), where ns and nrun are the slope of the
primordial mass power spectrum and the running spectral index respectively. It
is shown that an improvement of a factor 2 is expected on the running spectral
index from the combined data sets. Forecasts for error improvements from a wide
field space telescope lensing survey are also given.


title:
X-ray Preionisation Powered by Accretion on the First Black Holes. II:
  Cosmological Simulations and Observational Signatures

abstract:
  We use cosmological simulations to study the X-ray ionisation and heating of
the intergalactic medium by an early population of accreting black holes. By
considering observational constraints from the X-ray background, we find an
upper limit for the optical depth to Thompson scattering tau_e~0.17. The
redshifted soft X-ray background from these early sources produces:(i) fully
ionised atomic hydrogen in the low density intergalactic medium before redshift
z~7 (consequently stellar reionisation is characterised by an instantaneous
overlap phase of HII regions),(ii) a second HeII reionisation at z~3 and (iii)
heats the intergalactic medium to near 10000 K at low redshifts. The typical
luminosity in the soft X-ray band of the galaxies hosting the black holes is
about one order of magnitude below the sensitivity limit of the Chandra deep
field. About a thousand of these sources may be present per square arcmin of
the sky, producing detectable fluctuations. Few rarer objects could be luminous
enough to be visible in the Chandra deep field. XEUS and Con-X satellites will
be able to detect more of these sources that, if radio loud, could be used to
study the 21cm forest in absorption.A signature of an early X-ray preionisation
is the production of secondary CMB anisotropies on small angular scales. We
find that in these models the power spectrum of temperature fluctuations
increases with decreasing angular scale (dT~16 muK at 1arcsec scales), while
for stellar reionisation scenarios the power decreases on smaller scales. We
also show that the redshifted 21 cm radiation from neutral hydrogen can be
marginally detected in emission at redshifts 7<z<12. At a redshift of about
z~30 a stronger and narrower (in redshift space) signal in absorption against
the CMB, that is peculiar to these models,could be detectable.[abridged]


title: The flatness problem and $\Lambda$

abstract:
  By way of a complete integration of the Friedmann equations, in terms of
observables, it is shown that for the cosmological constant $\Lambda > 0$ there
exist non-flat FLRW models for which the total density parameter $\Omega$
remains $\sim 1$ throughout the entire history of the universe. Further, it is
shown that in a precise quantitative sense these models are not finely tuned.
When observations are brought to bear on the theory, and in particular the WMAP
observations, they confirm that we live in just such a universe. The conclusion
holds when the classical notion of $\Lambda$ is extended to dark energy.


title:
Astrometric confirmation of a wide low-mass companion to the planet host
  star HD89744

abstract:
  In our ongoing deep infrared imaging search for faint wide secondaries of
planet-candidate host stars we have confirmed astrometrically the companionship
of a low-mass object to be co-moving with HD89744, a companion-candidate
suggested already by Wilson et al. (2000). The derivation of the common proper
motion of HD89744 and its companion, which are separated by 62.996+-0.035
arcsec, is based on about 5 year epoch difference between 2MASS and our own
UKIRT/UFTI images. The companion effective temperature is about 2200 K and its
mass is in the range between 0.072 and 0.081 Msun, depending on the
evolutionary model. Therefore, HD89744B is either a very low mass stellar or a
heavy brown dwarf companion.


title:
Chandra Observations and Monte Carlo Simulations of the Grain-Scattered
  Halo of the Binary X-Ray Pulsar 4U 1538-52

abstract:
  Properties of the X-ray halo of the eclipsing X-ray pulsar 4U 1538-52 are
derived from a 25 ksec observation by the Chandra X-Ray Observatory. Profiles
of the halo, compiled in two energy ranges, 2 to 4 keV and 4 to 6 keV, and
three time intervals before and after an eclipse immersion, exhibit a
three-peak shape. The observed profiles are fitted by the profiles of a
simulated halo generated by a Monte Carlo ray-tracing code operating on a model
of three discrete clouds and a spectrum of the photons emitted by the source
over a period of time extending from 270 ksec before the observation began till
it ended. The distances of the two nearer dust clouds are fixed at the
distances of the peaks of atomic hydrogen derived from the 21-cm spectrum in
the direction of the X-ray source, namely at 1.30 and 2.56 kpc. A good fit is
achieved with the source at a distance 4.5 kpc, the distance of the third cloud
at 4.05 kpc, the total scattering optical depth of the three clouds equal to
0.159 at 3 keV, and the column density of hydrogen set to 4.6x10^22 cm^-2. With
Av=6.5 mag for the binary companion star, QV Nor, the ratio of the scattering
optical depth at 3 keV to the visual extinction is 0.0234 mag^-1.


title:
Distant field BHB stars and the mass of the Galaxy II: Photometry and
  spectroscopy of UKST candidates 16<B<19.5, 11<R<52 kpc

abstract:
  This is the second in a series of papers presenting a new calculation of the
mass of the Galaxy based on radial velocities and distances for a sample of
faint 16 < B < 21.3 field blue horizontal-branch (BHB) stars. We present
accurate BV CCD photometry and spectra for 142 candidate A-type stars selected
from ub_jr photometry of UK Schmidt telescope plates in six
high-Galactic-latitude fields. Classification of these candidates produces a
sample of 60 BHB stars at distances of 11-52 kpc from the Sun (mean 28 kpc),
with heliocentric line-of-sight velocities accurate to 15 km/s, and distance
errors < 10%. We provide a summary table listing coordinates and velocities of
these stars. The measured dispersion of the radial component of the
Galactocentric velocity for this sample is 108+-10 km/s, in agreement with a
recent study of the distant halo by Sirko and coworkers. Measurements of the Ca
II K line indicate that nearly all the stars are metal-poor with a mean [Fe/H]
= -1.8 with dispersion 0.5. Subsequent papers will describe a second survey of
BHBs to heliocentric distances 70 < R < 125 kpc and present a new estimate of
the mass of the Galaxy.


title:
Outflow structure and reconnection rate of the self-similar evolution
  model of fast magnetic reconnection

abstract:
  In order to understand the nature of magnetic reconnection in ``free space''
which is free from any influence of external circumstances, I have studied the
structure of spontaneous reconnection outflow using a shock tube approximation.
The reconnection system of this case continues to expand self-similarly. This
work aims 1) to solve the structure of reconnection outflow and 2) to clarify
the determination mechanism of reconnection rate of the ``self-similar
evolution model'' of fast reconnection.
  Many cases of reconnection in astrophysical phenomena are characterized by a
huge dynamic range of expansion in size ($\sim 10^7$ for typical solar flares).
Although such reconnection is intrinsically time dependent, a specialized model
underlying the situation has not been established yet.
  The theoretical contribution of this paper is in obtaining a solution for
outflow structure which is absent in our previous papers proposing the above
new model. The outflow has a shock tube-like structure, i.e., forward slow
shock, reverse fast shock and contact discontinuity between them. By solving
the structure in a sufficiently wide range of plasma-$\beta$: $0.001 \leq \beta
\leq 100$, we obtain an almost constant reconnection rate ($\sim 0.05$: this
value is the maximum for spontaneous reconnection and is consistent with
previous models) and a boundary value along the edge of the outflow (good
agreement with our simulation result) which is important to solve the inflow
region. Note that everything, including the reconnection rate, is spontaneously
determined by the reconnection system itself in our model.


title: Pulsar astrophysics : the glitch phenomenon

abstract:
  We briefly discuss a handful of topics in pulsar astrophysics, first some
general well-known features, then an overview of the glitch phenomenon and the
sort of information gathered about the internal structure and dynamics, and
finally the quandary posed by the precession of PSR B1828-11 a very important
clue pointing towards a novel paradigm for structure of the core regions. We
point out that "exotic" solutions for the precession puzzle would force a
consideration of exotic {\it glitch} mechanisms as well.


title: Chandra and FUSE spectroscopy of the hot bare stellar core H1504+65

abstract:
  H1504+65 is an extremely hot hydrogen-deficient white dwarf with an effective
temperature close to 200,000 K. We present new FUV and soft X-ray spectra
obtained with FUSE and Chandra, which confirm that H1504+65 has an atmosphere
primarily composed of carbon and oxygen. The Chandra LETG spectrum (60-160
Angstroem) shows a wealth of photospheric absorption lines from highly ionized
oxygen, neon, and - for the first time identified in this star - magnesium and
suggests relatively high Ne and Mg abundances. This corroborates an earlier
suggestion that H1504+65 represents a naked C/O stellar core or even the C/O
envelope of an O-Ne-Mg white dwarf.


title: Intracluster light at z~0.25 from SDSS imaging data

abstract:
  We investigate the broadband optical emission of diffuse intergalactic stars
in galaxy clusters at z~0.25 by means of an image stacking technique. The
images of 654 clusters, selected with the max-BCG algorithm from a subsample of
the SDSS-Data Release 1 (DR1), have been stacked after masking all the sources
detected down to very low S/N. The resulting images in the g, r and i bands
provide reliable photometric data at the level of >=30 mag arcsec^-2 (r band),
out to >~ 600 kpc from the Brightest Cluster Galaxy (BCG). Our analysis shows
that: i) the IntraCluster Light (ICL) is much more concentrated than the galaxy
light, contributing ~30% of the total cluster optical emission at R=100 kpc,
but less than 10% at R>500 kpc; ii) the ICL contributes between 15 and 20% of
the total cluster optical luminosity between the optical radius (mu_r=25 mag
arcsec^-2) of the BCG and 500 kpc; iii) the colours of the ICL are consistent
with the global colours of the cluster galaxies, with little evidence for
redder g-r.


title: IGR J19140+098, a new INTEGRAL transient

abstract:
  IGR J19140+098 (SIMBAD corrected name IGR J19140+0951) is a new X-ray
transient, discovered by INTEGRAL during an observation of GRS 1915+015. The
source presents strong variations on timescales from seconds to days. We
present results of multiwavelength observations, including spectral analysis of
INTEGRAL observations, and propose that IGR J19140+098 is a Galactic X-ray
binary. Further classification of the source is also discussed.


title:
The effects of spin-down on the structure and evolution of pulsar wind
  nebulae

abstract:
  We present high resolution spherically symmetric relativistic
magnetohydrodynamical simulations of the evolution of a pulsar wind nebula
inside the free expanding ejecta of the supernova progenitor. The evolution is
followed starting from a few years after the supernova explosion and up to an
age of the remnant of 1500 years. We consider different values of the pulsar
wind magnetization parameter and also different braking indices for the
spin-down process. We compare the numerical results with those derived through
an approximate semi-analytical approach that allows us to trace the time
evolution of the positions of both the pulsar wind termination shock and the
contact discontinuity between the nebula and the supernova ejecta. We also
discuss, whenever a comparison is possible, to what extent our numerical
results agree with former self-similar models, and how these models could be
adapted to take into account the temporal evolution of the system. The inferred
magnetization of the pulsar wind could be an order of magnitude lower than that
derived from time independent analytic models.


title: Rotation of the Universe and the angular momenta of celestial bodies

abstract:
  We discuss the equation of motion of the rotating homogenous and isotropic
model of the Universe. We show that the model predicts the presence of a
minimum in the relation between the mass of an astronomical object and its
angular momentum. We show that this relation appears to be universal, and we
predict the masses of structures with minimal angular momenta in agreement with
observations. In such a manner we suggest the possibility at acquirement of
angular momenta of celestial bodies during their formation from the global
rotation of the Universe.


title:
Towards an Adequate Method to Isolate Spectroscopic Families of Diffuse
  Interstell Bands

abstract:
  We divide some of the observed diffuse interstellar bands (DIBs) into
families which appear to have spectral structures of single species. Three
different methods are applied to separate such families, exploring the best
approach for future investigations of this type. Starting with statistical
treatment of the data, we found that statistical methods by themselves give
insufficient results. Two other methods of data analysis ("Averaging EWs" and
"Investigating the figures with arranged spectrograms") were found to be more
useful as tools for finding the spectroscopic families of DIBs. On the basis of
these methods, we suggest some candidates as "relatives" of 5780 and 5797
bands.


title: Evolution of optically faint AGN from COMBO-17 and GEMS

abstract:
  We have mapped the AGN luminosity function and its evolution between z=1 and
z=5 down to apparent magnitudes of $R<24$. Within the GEMS project we have
analysed HST-ACS images of many AGN in the Extended Chandra Deep Field South,
enabling us to assess the evolution of AGN host galaxy properties with cosmic
time.


title:
Revealing the nature of the highly obscured galactic source IGR
  J16318-4848

abstract:
  The X-ray source IGR J16318-4848 was the first source discovered by INTEGRAL
on 2003, January 29. We carried out optical and near-infrared (NIR)
observations at the European Southern Observatory (ESO La Silla) in the course
of a Target of Opportunity (ToO) programme. We discovered the optical
counterpart and confirmed an already proposed NIR candidate. NIR spectroscopy
revealed a large amount of emission lines, including forbidden iron lines and
P-Cygni profiles. The spectral energy distribution of the source points towards
a high luminosity and a high temperature, with an absorption greater than the
interstellar absorption, but two orders of magnitude lower than the X-ray
absorption. We show that the source is an High Mass X-ray binary (HMXB) at a
distance between ~1 and 6 kpc, the mass donor being an early-type star,
probably a sgB[e] star, surrounded by a rich and absorbing circumstellar
material. This would make the second High Mass X-ray Binary (HMXB) with a
sgB[e] star after CI Cam, indicating that a new class of strongly absorbed
X-ray binaries is being unveiled by INTEGRAL.


title: H_2 Line Emission Associated with the Formation of the First Stars

abstract:
  Molecular hydrogen line radiation emitted in formation events of
first-generation stars are evaluated in a discussion of its detectability by
future observational facilities. H_2 luminosity evolution from the onset of
prestellar collapse until the formation of a \sim 100 M_{\odot} protostar is
followed. Calculations are extended not only to the early phase of the runaway
collapse but also to the later phase of accretion, whose observational features
have not been studied before. Contrary to the runaway collapse phase, where the
pure-rotational lines are always dominant, in the accretion phase rovibrational
line emission becomes prominent. The maximum luminosity is also attained in the
accretion phase for strong emission lines. The peak intensity of the strongest
rovibrational line reaches \sim 10^{-29} (W/m^2), corresponding to the flux
density of 10^{-5} (\mu Jy), for a source at the typical redshift of
first-generation star formation, 1+z=20. Although the redshifted rovibrational
H_2 emission from such an epoch falls in the wavelength range of the
next-generation infrared satellite, Space Infrared Telescope for Cosmology and
Astrophysics, for exceeding the detection threshold 10^7 such protostars are
required to reach the maximum luminosity simultaneously in a pregalactic cloud.
It is improbable that this condition is satisfied in a realistic scenario of
early structure formation.


title: Quasars and Narrow-Line Seyfert 1s: Trends and Selection Effects

abstract:
  The SDSS has opened a new era for the study of AGN spectroscopic properties
and how these depend on luminosity and time. In this presentation we review
some of the current issues and problems in studies of high-redshift quasars and
Narrow-Line Seyfert 1 galaxies. Investigations employing SDSS will, in some
situations, still have to pay attention to selection biases and other
fundamental limitations of the data.


title:
Estimating the Ages of Bars: Implications for the Bar-AGN-Star Formation
  Connection

abstract:
  In an effort to elevate to higher grounds our understanding on the impact of
the formation and evolution of bars in the formation and evolution of galaxies,
we have developed a diagnostic tool to distinguish between recently formed and
evolved bars. Our method was applied in the study of a sample of 14 galaxies
and revealed that, apparently, AGN activity tends to appear in galaxies which
have young bars rather than evolved bars. This suggests that the time scale for
the fueling of AGN by bars is short, and may help to explain, for instance, why
there is not a clear correlation between the presence of bars and AGN in
galaxies.


title: NGC2180: a disrupting open cluster

abstract:
  The spatial dependence of luminosity and mass functions of evolved open
clusters is discussed in this work using J and H 2MASS photometry. The target
objects are the overlooked open cluster NGC2180 and the intermediate-age open
cluster NGC3680. We conclude that, although in an advanced dynamical state
(mass segregated), NGC3680 does not present strong signs of dissolution. On the
other hand, NGC2180 presents flat, eroded LFs throughout its structure,
indicating that in addition to mass segregation, Galactic tidal stripping has
been effective in depleting this cluster of stars. Accordingly, NGC2180 may be
the missing link between evolved open clusters and remnants. We study both
clusters in the context of dynamical states estimated from diagnostic-diagrams
involving photometric and structural parameters. Both clusters are dynamically
evolved systems. In particular, NGC2180 is closer to open cluster remnants than
NGC3680.


title: Strategies for Imaging Faint Extended Sources in the Near-Infrared

abstract:
  Quantitative information about variations in the background at J and K' are
presented and used to develop guidelines for the acquisition and reduction of
ground-based images of faint extended sources in the near-infrared, especially
those which occupy a significant fraction of the field of view of a detector or
which are located in areas crowded with foreground or background sources.
Findings are based primarily upon data acquired over three photometric nights
with the 3.6x3.6 arcmin CFHT-IR array on the Canada-France-Hawaii Telescope
atop Mauna Kea. Although some results are specific to CFHT, overall conclusions
should be useful in guiding observing and reduction strategies of extended
objects elsewhere.


title:
Collapse of Uniformly Rotating Stars to Black Holes and the Formation of
  Disks

abstract:
  Simulations in general relativity show that the outcome of collapse of a
marginally unstable, uniformly rotating star spinning at the mass-shedding
limit depends critically on the equation of state. For a very stiff equation of
state, which is likely to characterize a neutron star, essentially all of the
mass and angular momentum of the progenitor are swallowed by the Kerr black
hole formed during the collapse, leaving nearly no residual gas to form a disk.
For a soft equation of state with an adiabatic index \Gamma - 4/3 << 1, which
characterizes a very massive or supermassive star supported predominantly by
thermal radiation pressure, as much as 10% of the mass of the progenitor avoids
capture and goes into a disk about the central hole. We present a semi-analytic
calculation that corroborates these numerical findings and shows how the final
outcome of such a collapse may be determined from simple physical
considerations. In particular, we employ a simple energy variational principle
with an approximate, post-Newtonian energy functional to determine the
structure of a uniformly rotating, polytropic star at the onset of collapse as
a function of polytropic index n, where \Gamma = 1+1/n. We then use this data
to calculate the mass and spin of the final black hole and ambient disk. We
show that the fraction of the total mass that remains in the disk falls off
sharply as 3-n (equivalently, \Gamma - 4/3) increases.


title: The Distribution of Mass and Light in Cluster Infall Regions

abstract:
  The CAIRNS (Cluster And Infall Region Nearby Survey) project is a large
spectroscopic survey of the infall regions surrounding nine nearby rich
clusters of galaxies. I describe the survey and use the kinematics of galaxies
in the infall regions to estimate the cluster mass profiles. At small radii,
these mass profiles are consistent with independent mass estimates from X-ray
observations and Jeans analysis. I demonstrate the dependence of mass-to-light
ratios on environment by combining these mass profiles with Two-Micron All-Sky
Survey (2MASS) photometry. Near-infrared light is more extended than mass in
these clusters, suggesting that dense cluster cores are less efficient at
forming galaxies and/or more efficient at disrupting them. At large radii,
galaxy populations in cluster infall regions closely resemble those in the
field. The mass-to-light ratio at these radii should therefore be a good probe
of the global mass-to-light ratio. The mass-to-light ratio in the infall region
yields a surprisingly low estimate of $\Omega_m \sim 0.1$.


title:
Molecular hydrogen formation on dust grains in the high redshift
  universe

abstract:
  We study the formation of molecular hydrogen on dust grain surfaces and apply
our results to the high redshift universe. We find that a range of physical
parameters, in particular dust temperature and gas temperature, but not so much
dust surface composition, influence the formation rate of H$_2$. The H$_2$
formation rate is found to be suppressed above gas kinetic temperatures of a
few hundred K and for dust temperatures above 200-300 K and below 10 K. We
highlight the differences between our treatment of the H$_2$ formation process
and other descriptions in the literature. We also study the relative importance
of H$_2$ formation on dust grains with respect to molecular hydrogen formation
in the gas phase, through the H$^-$ route. The ratio of formation rates of
these two routes depends to a large part on the dust abundance, on the electron
abundance, and also on the relative strength of the FUV (extra-)galactic
radiation field. We find that for a cosmological evolution of the star
formation rate and dust density consistent with the Madau plot, a positive
feedback effect on the abundance of H$_2$ due to the presence of dust grains
can occur at redshifts $z\ge 3$. This effect occurs for a dust-to-gas mass
ratio as small as 10$^{-3}$ of the galactic value.


title:
GBT Exploratory Time Observations of the Double-Pulsar System PSR
  J0737-3039

abstract:
  We report results from Exploratory Time observations of the double-pulsar
system PSR J0737-3039 using the Green Bank Telescope (GBT). The large gain of
the GBT, the diversity of the pulsar backends, and the four different frequency
bands used have allowed us to make interesting measurements of a wide variety
of phenomena. Here we briefly describe results from high-precision timing,
polarization, eclipse, scintillation velocity, and single-pulse work.


title: Long-Term Profile Variability of Double-Peaked Emmission Lines in AGNs

abstract:
  An increasing number of AGNs exhibit broad, double-peaked Balmer emission
lines, which arise from the outer regions of the accretion disk which fuels the
AGN. The line profiles vary on timescales of 5--10 years. Our group has
monitored a set of 20 double-peaked emitters for the past 8 years (longer for
some objects). Here we describe a project to characterize the variability
patterns of the double-peaked H alpha line profiles and compare with those of
two simple models: a circular disk with a spiral arm and an elliptical disk.


title: Orbital Parameters for the Black Hole Binary XTE J1650-500

abstract:
  (Shortened) We present R-band photometry of the X-ray transient and candidate
black hole binary XTE J1650-500 obtained between 2003 May and August with the
6.5m Clay Telescope. A timing analysis of these data reveals a photometric
period of 0.3205 +/- 0.0007 days (i.e. 7.63 hr) with a possible alias at 0.3785
days (9.12 hr). Our photometry completely rules out the previously published
spectroscopic period of 0.212 days (5.09 hr). Consequently, we reanalyzed the
15 archival ESO/VLT spectra (obtained 2002 June by Sanchez-Fernandez et al.)
that were the basis of the previously published spectroscopic period. We used a
``restframe search'' technique that is well suited for cases when the
signal-to-noise ratio of individual spectra is low. The results confirmed the
photometric period of 0.3205 days, and rule out the alias period near 0.38
days. The best value for the velocity semiamplitude of the companion star is
K_2 = 435 +/- 30 km/sec, and the corresponding optical mass function is f(M) =
2.73 +/- 0.56 solar masses. The amplitude of the phased R-band light curve is
0.2 magnitudes, which gives a lower limit to the inclination of 50 +/- 3
degrees in the limiting case of no contribution to the R-band light curve from
the accretion disk. If the mass ratio of XTE J1650-500 is similar to the mass
ratios of other black hole binaries like A0620-00 or GRS 1124-683 (e.g. Q >~
10), then our lower limit to the inclination gives an upper limit to the mass
of the black hole in XTE J1650-500 of M_1 <~ 7.3 solar masses. However, the
mass can be considerably lower if the R-band flux is dominated by the accretion
disk. For example, if the accretion disk does contribute 80% of the flux, as
our preliminary results suggest, then the black hole mass would be only about 4
solar masses.


title:
Mass distribution of DA white dwarfs in the First Data Release of the
  Sloan Digital Sky Survey

abstract:
  We investigate the sample of 1175 new nonmagnetic DA white dwarfs with the
effective temperatures T_eff > 12000 K, which were extracted from the Data
Release 1 of the Sloan Digital Sky Survey. We determined masses, radii, and
bolometric luminosities of stars in the sample. The above parameters were
derived from the effective temperatures T_eff and surface gravities log g
published in the DR1, and the new theoretical M - R relations for carbon-core
and oxygen-core white dwarfs. Mass distribution of white dwarfs in this sample
exhibits the peak at M = 0.562 M_sol (carbon core stars), and the tail towards
higher masses. Both the shape of the mass distribution function and the
empirical mass - radius relation are practically identical for white dwarfs
with either pure carbon or pure oxygen cores.


title: Excess Ionization and Soft X-ray Emission from Cooling Flow Clusters

abstract:
  X-ray spectroscopy of cooling-flow clusters reveal an unexpected deficit of
soft X-ray emission lines from gas at ~1/3 of the ambient plasma temperature,
across a wide range of X-ray luminosities and virial temperatures. We propose
excess ionization from either a population of suprathermal electrons or
photoionization by X-ray continuum emission from hot gas or a central AGN as a
means of decoupling the thermal state of the gas from its emission line
spectrum. The former effect is thought to operate in the solar corona. Because
they generally become important at some fixed fraction of the cluster gas
temperature, such mechanisms could in principle explain both the universality
and temperature dependence of the emission line suppression, properties which
none of the present-day models based on gas heating can explain. Ultimately
these models cannot explain the observations; however, they have attractive and
robust features which could be useful in elucidating a final solution to the
soft X-ray deficit.


title: Submillimeter Array Observations of L1551 IRS 5 in CS (J=7-6)

abstract:
  We have imaged the circumstellar envelope around the binary protostar L1551
IRS 5 in CS (J=7-6) and 343 GHz continuum emission at ~ 3 arcsec resolution
using the Submillimeter Array. The continuum emission shows an elongated
structure (~ 220 x 100 AU) around the binary perpendicular to the axis of the
associated radio jet. The CS emission extends over ~ 400 AU, appears
approximately circularly symmetric, and shows a velocity gradient from
southeast (blueshifted) to northwest (redshifted). The direction of the
velocity gradient is different from that observed in C18O (J=1-0). This may be
because rotation is more dominant in the CS envelope than the C18O envelope, in
which both infall and rotation exist. The CS emission may be divided into two
velocity components: (1) a "high" velocity disk-like structure surrounding the
protostar, +-1.0 - 1.5 km s-1 from the systemic velocity, and (2) a "low"
velocity structure, located southwest of the protostar, < 1.0 km s -1 from the
systemic velocity. The high-velocity component traces warm and dense gas with
kinematics consistent with rotation around the protostar. The low-velocity
component may arise from dense gas entrained in the outflow. Alternatively,
this component may trace infalling and rotating gas in an envelope with a
vertical structure.


title:
VLBI imaging of OH absorption: The puzzle of the nuclear region of NGC
  3079

abstract:
  Broad hydroxyl (OH) absorption-lines in the 1667 MHz and 1665 MHz transition
towards the central region of NGC 3079 have been observed at high resolution
with the European VLBI Network (EVN). Velocity fields of two OH absorption
components were resolved across the unresolved nuclear radio continuum of ~10
parsecs. The velocity field of the OH absorption close to the systemic velocity
shows rotation in nearly the same sense as the edge-on galactic-scale molecular
disk probed by CO(1-0) emission. The velocity field of the blue-shifted OH
absorption displays a gradient in almost the opposite direction. The
blue-shifted velocity field represents a non-rotational component, which may
trace an outflow from the nucleus, or material driven and shocked by the
kiloparsec-scale superbubble. This OH absorption component traces a structure
that does not support a counter-rotating disk suggested on the basis of the
neutral hydrogen absorption.


title: The large-scale bias of the hard X-ray background

abstract:
  Recent deep X-ray surveys combined with spectroscopic identification of the
sources have allowed the determination of the rest-frame 2-8 keV luminosity as
a function of redshift. In addition, an analysis of the HEAO1 A2 2-10 keV
full-sky map of the X-ray background (XRB) reveals clustering on the scale of
several degrees. Combining these two results in the context of the currently
favored Lambda-CDM cosmological model implies an average X-ray bias factor,
b_x, of b_x^2 = 1.12 +- 0.33, i.e., b_x = 1.06 +- 0.16. These error estimates
include only statistical error; the systematic error sources, while comparable,
appear to be sub-dominant. This result is in contrast to the large biases of
some previous estimates and is more in line with current estimates of the
optical bias of L* galaxies.


title: Shear Selected Cluster Cosmology I: Tomography and Optimal Filtering

abstract:
  We study the potential of weak lensing surveys to detect clusters of
galaxies, using a fast Particle Mesh cosmological N-body simulation algorithm
specifically tailored to investigate the statistics of these mass-selected
clusters. In particular, we explore the degree to which the radial positions of
galaxy clusters can be determined tomographically, by using photometric
redshifts of background source galaxies. We quantify the errors in the
tomographic redshifts, and study their dependence on mass, redshift, detection
significance, and filtering scheme. A Tomographic Matched Filtering (TMF)
scheme, which combines tomography and matched filtering, is introduced, which
optimally detects clusters of galaxies in weak lensing surveys. The TMF
exploits the extra information provided by photometric redshifts of background
source galaxies, neglected in previous studies, to optimally weight the
sources. The efficacy and reliability of the TMF is investigated using a large
ensemble of mock observations from our simulations and detailed comparisons are
made to other filters. Using photometric redshift information with the TMF
enhances the number of clusters detected with S/N > 4.5 by as much as 76%, and
it increases the dynamic range of weak lensing searches for clusters, detecting
more high redshift clusters and extending the mass sensitivity down to the
scale of large groups. Furthermore, we find that coarsely binning source
galaxies in as few as three redshift bins is sufficient to realize the gains of
the TMF. Thus, the tomographic filtering techniques presented here can be
applied to current ground based weak lensing data in as few as three bands.
Cosmological applications of mass selected cluster samples are also discussed.
(abridged)


title: Simulating the Formation of Galaxy Clusters

abstract:
  We study the effects of radiative cooling, star formation and stellar
feedback on the properties and evolution of galaxy clusters using
high-resolution Adaptive Mesh Refinement N-body+gasdynamics simulations of
clusters forming in the LCDM universe. Cooling leads to the condensation of gas
in the inner regions of clusters, which in turn leads to steepening of the dark
matter profile. The cooling gas is replaced by the higher-entropy gas from the
outer regions, which raises the entropy and temperature of gas in the cluster
core. The magnitude of these effects is likely overestimated in the current
simulations because they suffer from the overcooling problem: a much larger
fraction of baryons is in the form of cold gas and stars than is observed. We
find that the thermal stellar feedback alone does not remedy this problem.
Additional ad-hoc preheating can lower the amount of cold gas but a simple
uniform preheating results in incorrect star formation history, as it delays
the bulk of star formation until z<1. Our analysis shows that the overcooling
in a cluster as a whole is really the overcooling in the central galaxy and its
progenitors at high redshifts. This indicates that an additional heating
mechanism that can continuously heat the gas in the cluster core is required to
reproduce the observed cluster properties. Energy injection by the Active
Galactic Nuclei, which may provide such heating, may thus be an important
missing ingredient in the current theoretical models of cluster formation.


title: Modeling the near-infrared lines of O-type stars

abstract:
  We use a grid of 30 line-blanketed unified stellar photosphere and wind
models for O-type stars; computed with the code CMFGEN in order to evaluate its
potential in the near-infrared spectral domain. The grid includes dwarfs,
giants and supergiants. We analyse the equivalent width behaviour of the 20
strongest lines of hydrogen and helium in spectral windows that can be observed
using ground-based instrumentation and compare the results with observations.
Our main findings are that: i) HeI/HeII line ratios in the J, H and K bands
correlate well with the optical ratio employed in spectral classification, and
can therefore be used to determine the spectral type; ii) in supergiant stars
the transition from the stellar photosphere to the wind follows a shallower
density gradient than the standard approach followed in our models, which can
be mimicked by adopting a lower gravity in our prescription of the density
stratification. iii) the Brackett gamma line poses a number of peculiar
problems which partly might be related to wind clumping, and iv) the Brackett
alpha line is an excellent mass-loss indicator. For the first and last item we
provide quantitative calibrations.


title:
High energy gamma ray counterparts of astrophysical sources of
  ultra-high energy cosmic rays

abstract:
  If ultra-high energy cosmic rays (UHECRs) are accelerated at astrophysical
point sources, the identification of such sources can be achieved if there is
some kind of radiation at observable wavelengths that may be associated with
the acceleration and/or propagation processes. No radiation of this type has so
far been detected or at least no such connection has been claimed. The process
of photopion production during the propagation of UHECRs from the sources to
the Earth results in the generation of charged and neutral pions. The neutral
(charged) pions in turn decay to gamma quanta and electrons that initiate an
electromagnetic cascade in the universal photon background. We calculate the
flux of this gamma radiation in the GeV-TeV energy range and find that for
source luminosities compatible with those expected from small scale
anisotropies in the directions of arrival of UHECRs, the fluxes can be
detectable by future Cerenkov gamma ray telescopes, such as VERITAS and HESS,
provided the intergalactic magnetic field is not larger than $\sim 10^{-10}$
Gauss and for source distances comparable with the loss length for photopion
production.


title:
A search for low surface brightness dwarf galaxies in different
  environments

abstract:
  According to the Cold Dark Matter (CDM) hierarchical clustering theory of
galaxy and large scale structure formation, there should be numerous low mass
dark matter haloes present in the Universe today. If these haloes contain
sufficient stars they should be detectable as low luminosity stellar systems or
dwarf galaxies. We have previously described a new detection method for faint
low surface brightness objects and shown that there are relatively large
numbers of very faint dwarf galaxies in the nearby Virgo cluster. In this paper
we present results from a similar survey carried out on the Millennium Galaxy
strip which runs along the celestial equator and samples a very different
galaxy environment. We show that the dwarf-to-giant galaxy number ratio along
this strip ranges from 0.7:1 to, at most, 6:1, corresponding to a flat
luminosity function (alpha approx -0.8 to -1.0). This is very different to our
value of 20:1 for the Virgo cluster. There is no population of low surface
brightness dwarf galaxies in the field that have gone undetected by the
redshift surveys. This result is exactly opposite to what CDM models predict
for the environmental dependence of the dark matter mass function which is that
there are proportionally more small dark matter haloes in lower density
environments.


title: XMM-Newton Observation of Solar Wind Charge Exchange Emission

abstract:
  We present an XMM-Newton spectrum of diffuse X-ray emission from within the
solar system. The spectrum is dominated by probable C VI lines at 0.37 keV and
0.46 keV, an O VII line at 0.56 keV, O VIII lines at 0.65 keV and ~0.8 keV, Ne
IX lines at ~0.92 keV, and Mg XI lines at ~1.35 keV. This spectrum is
consistent with that expected from charge exchange emission between the highly
ionized solar wind and either interstellar neutrals in the heliosphere or
material from Earth's exosphere. The emission is clearly seen as a low-energy
(E<1.5 keV) spectral enhancement in one of a series of four observations of the
Hubble Deep Field North. The X-ray enhancement is concurrent with an
enhancement in the solar wind measured by ACE, Wind, and SoHO spacecraft. The
solar wind enhancement reaches a flux level an order of magnitude more intense
than typical fluxes at 1 AU, and has a significantly enhanced O^{+7}/O^{+6}
ratio. Besides being of interest in its own right for studies of the solar
system, this emission can have significant consequences for observations of
cosmological objects. It can provide emission lines at zero redshift which are
of particular interest in studies of diffuse thermal emission (e.g., O VII and
O VIII), and which can therefore act as contamination in the spectra of objects
which cover the entire detector field of view. We propose the use of solar wind
monitoring data as a diagnostic to screen for such possibilities.


title:
Axially symmetric relativistic MHD simulations of Pulsar Wind Nebulae in
  Supernova Remnants - On the origin of torus and jet-like features

abstract:
  The structure and the evolution of Pulsar Wind Nebulae (PWNe) are studied by
means of two-dimensional axisymmetric relativistic magnetohydrodynamic (RMHD)
simulations. After the first imaging of the Crab Nebula with Chandra, a growing
number of objects has been found to show in the X-rays spatial features such as
rings and jets, that clearly cannot be accounted for within the standard
framework of one-dimensional semi-analytical models. The most promising
explanation suggested so far is based on the combined effects of the latitude
dependence of the pulsar wind energy flux, shaping the wind termination shock
and naturally providing a higher equatorial emission, and of the wind
magnetization, likely responsible for the jet collimation by hoop stresses
downstream of the shock. This scenario is investigated here by following the
evolution of a PWN interacting with the confining Supernova Remnant (SNR), from
the free expansion to the beginning of the reverberation phase. Our results
confirm the oblate shape of the wind termination shock and the formation of a
polar jet with supersonic velocities (v~0.5-0.7 c) for high enough values of
the equatorial wind magnetization parameter (sigma~0.01).


title: Non-Random Phases in Non-Trivial Topologies

abstract:
  We present a new technique for constraining the topology of the universe. The
method exploits the existence of correlations in the phases of the spherical
harmonic coefficients of the CMB temperature pattern associated with matched
pairs of circles seen in the sky in universes with non-trivial topology. The
method is computationally faster than all other statistics developed to hunt
for these matched circles. We applied the method to a range of simulations with
topologies of various forms and on different scales. A characteristic form of
phase correlation is found in the simulations. We also applied the method to
preliminary CMB maps derived from WMAP, but the separation of topological
effects from, e.g., foregrounds is not straightforward.


title:
Stellar Population Properties in the Nuclei and Bulges of the Nearby
  Lenticular Galaxies

abstract:
  The properties of stellar populations in the centers of 54 nearby lenticular
galaxies are investigated by means of 2D spectroscopy, with the Multi-Pupil
Spectrograph of the 6m telescope of SAO RAS; the unresolved nuclei and their
surrounding bulges are analysed separately. All the galaxies are divided into
four subgroups depending on the environments type. Clear distinctions between
the mean stellar ages and abundance ratios of the nuclei and of the bulges,
both, are found for the S0s in clusters and group centers, on the one hand, and
in field, on the other hand.


title:
Theoretical isochrones in several photometric systems II. The Sloan
  Digital Sky Survey ugriz system

abstract:
  Following Paper I, we provide extended tables of bolometric corrections,
extinction coefficients, stellar isochrones, and integrated magnitudes and
colours of single-burst stellar populations, for the Sloan Digital Sky Survey
(SDSS) ugriz photometric system. They are tested on comparisons with DR1 data
for a few stellar systems, namely the Palomar 5 and NGC 2419 globular clusters
and the Draco dSph galaxy.


title: The Luminosity Function of Galaxies in the Hercules Cluster

abstract:
  We have imaged $\sim$ 1 deg$^{2}$ in the V-band in the direction of the
Hercules Cluster (Abell 2151). The data are used to compute for the first time
the luminosity function (LF) of galaxies in the cluster down to the dwarf
regime (M$_{lim}$ $\sim$ -13.85). The global LF is well described by a
Schechter function (\cite{schechter76}) with best-fit parameters $\alpha$ =
-1.30 $\pm$ 0.06 and M$_V$$^*$ = -21.25 $\pm$ 0.25. The radial dependence of
the LF has also been studied, finding that it turns out to be almost constant
within the errors even further away than the virial radius. Given the presence
of significant substructure within the cluster, we have analized the LFs in
different regions. While two of the subclusters present LFs consistent with
each other and with the global one, the southernmost one exhibits a somewhat
steeper faint-end slope.