title:
TV Corvi Revisited: Precursor and Superhump Period Derivative Linked to
  the Disk Instability Model

abstract:
  We report optical photometric observations of four superoutbursts of the
short-period dwarf nova TV Crv. This object experiences two types of
superoutbursts; one with a precursor and the other without. The superhump
period and period excess of TV Crv are accurately determined to be 0.065028 +/-
0.000008 d and 0.0342 +/- 0.0021, respectively. This large excess implies a
relatively large mass ratio of the binary components (M_2/M_1), though it has a
short orbital period. The two types of superoutbursts can be explained by the
thermal-tidal instability model for systems having large mass ratios. Our
observations reveal that superhump period derivatives are variable in distinct
superoutbursts. The variation is apparently related to the presence or absence
of a precursor. We propose that the superhump period derivative depends on the
maximum disk radius during outbursts. We investigate the relationship of the
type of superoutbursts and the superhump period derivative for known sources.
In the case of superoutbursts without a precursor, superhump period derivatives
tend to be larger than those in precursor-main type superoutbursts, which is
consistent with our scenario.


title: Interacting Phantom Energy

abstract:
  We investigate the role of a suitable interaction between a matter fluid and
a phantom field for the coincidence problem. There exists a stationary scaling
solution which is a stable attractor at late times. Furthermore, the cosmic
doomsday is avoided in one region of the parameter space.


title:
Predictions for Cosmological Infrared Surveys with Herschel from a
  Mid-Infrared Phenomenological Evolution Model

abstract:
  We make predictions for the cosmological surveys to be conducted by the
future Herschel mission operating in the far-infrared. The far-infrared bands
match the peak of the CIRB, the brightest background of astrophysical origin.
Therefore, surveys in these bands will provide essential information on the
evolutionary properties of Luminous and Ultra-Luminous Infrared Galaxies (LIGs
and ULIGs), starburst and normal galaxies. Our predictions are based on a new
phenomenological model obtained from the 15-micron luminosity function of
galaxies and AGN, fitting all the ISOCAM observables (source counts and
redshift distributions) and also the recently published Spitzer source counts
in the 24-micron band. We discuss the confusion noise due to extragalactic
sources, depending strongly on the shape of the source counts and on the
telescope parameters. We derive the fraction of the CIRB expected to be
resolved by Herschel in the different wavebands and we discuss extragalactic
surveys that could be carried on by Herschel for different scientific
puropouses (i.e. ultra-deep, deep and shallow).


title: How Protostellar Outflows Help Massive Stars Form

abstract:
  We consider the effects of an outflow on radiation escaping from the
infalling envelope around a massive protostar. Using numerical radiative
transfer calculations, we show that outflows with properties comparable to
those observed around massive stars lead to significant anisotropy in the
stellar radiation field, which greatly reduces the radiation pressure
experienced by gas in the infalling envelope. This means that radiation
pressure is a much less significant barrier to massive star formation than has
previously been thought.


title: An XMM-Newton view of the cluster of galaxies Abell 85

abstract:
  We have observed the cluster of galaxies Abell 85 with XMM-Newton. These data
have allowed us to confirm in a previous paper the existence of the extended 4
Mpc filament detected by the ROSAT PSPC in the neighbourhood of this cluster,
and to determine an X-ray temperature of about about 2 keV. We now present a
thorough analysis of the properties of the X-ray gas in the cluster itself,
including temperature and metallicity maps for the entire cluster. These
results show that Abell 85 had intense merging activity in the past and is not
fully relaxed, even in the central region. We have also determined the
individual abundances for some iron-group metals and alpha-elements in various
regions; the ratios of these metallicities to the iron abundance show that both
supernova types Ia and II must be involved in the intra-cluster gas enrichment.
Spectral analysis of the central region suggests a different redshift of the
X-ray emitting gas compared to the mean cluster velocity derived from galaxy
member redshifts. We discuss the implications of the difference between the cD
galaxy redshift, the mean galaxy redshift and the hot gas redshift, as well as
the possibility of several groups being accreted on to Abell 85. Finally, we
obtain the dynamical mass profile and baryon fraction taking into account the
new determined temperature profile. The dynamical mass in Abell 85 has a steep
density profile, similar to the ones found in N-body simulations.


title: The merging/AGN connection II. Ionization of the circumnuclear regions

abstract:
  We report the first results of a study of a sample of 20 galaxy
mergers/interacting systems, using the VIMOS and PMAS integral field
spectrographs. For each object, we extracted the integrated spectrum of the
central regions and analyzed the ionization state using classical diagnostic
diagrams (Veilleux & Osterbrock 1987). There is evidence of AGN ionization in 4
of the objects, i.e. 20% of the sample, a considerably higher fraction than
found in previous studies ~4%


title: Environmental Enhancement of DM Haloes

abstract:
  We study the properties of dark matter haloes of a LCDM model in different
environments. Using the distance of the 5th nearest neighbour as an
environmental density indicator, we show that haloes in a high density
environment are more massive, richer, have larger radii and larger velocity
dispersions than haloes in a low density environment. Haloes in high density
regions move with larger velocities, and are more spherical than haloes in low
density regions. In addition, low mass haloes in the vicinity of the most
massive haloes are themselves more massive, larger, and have larger rms
velocities and larger 3D velocities than low mass haloes far from massive
haloes. The velocities of low mass haloes near massive haloes increase with the
parent halo mass. Our results are in agreement with recent findings about
environmental effects for groups and clusters of galaxies from deep (SDSS and
LCRS) surveys.


title: Asteroseismology of Procyon A with SARG at TNG

abstract:
  We present high precision radial velocity measurements on the F5 IV star
alpha CMi obtained by the SARG spectrograph at TNG (Telescopio Nazionale
Galileo) exploiting the iodine cell technique. The time series of about 950
spectra of Procyon A taken during 6 observation nights are affected by an
individual error of 1.3 m/s. Thanks to the iodine cell technique, the
spectrograph contribution to the Doppler shift measurement error is quite
negligible and our error is dominated by the photon statistics Brown et al
1994. An excess of power between 0.5 and 1.5 mHz, detected also by Martic et
al. 2004 has been found. We determined a large separation frequency Delta nu0 =
56\pm 2 microHz, consistent with both theoretical estimates Chaboyer et al.
1999 and previous observations Martic et al. 2004.


title: Optical Linear Polarization of Late M- and L-Type Dwarfs

abstract:
  (Abridged). We report on the linear polarimetric observations in the Johnson
I filter of 44 M6-L7.5 ultracool dwarfs (2800-1400 K). Eleven (10 L and 1 M)
dwarfs appear to have significant linear polarization (P = 0.2-2.5%). We have
compared the M- and L-dwarf populations finding evidence for a larger frequency
of high I-band polarization in the coolest objects, supporting the presence of
significant amounts of dust in L-dwarfs. The probable polarizing mechanism is
related to the presence of heterogeneous dust clouds nonuniformly distributed
across the visible photospheres and the asymmetric shape of the objects. In
some young ultracool dwarfs, surrounding dusty disks may also yield
polarization. For polarimetric detections, a trend for slightly larger
polarization from L0 to L6.5 may be present in our data, suggesting changes in
the distribution of the grain properties, vertical height of the clouds,
metallicity, age, and rotation speed. One of our targets is the peculiar brown
dwarf (BD) 2MASS J2244+20 (L6.5), which shows the largest I-band polarization
degree. Its origin may lie in a surrounding dusty disk or rather large
photospheric dust grains. The M7 young BD CFHT-BD-Tau 4 and the L3.5 field
dwarf 2MASS J0036+18 were also observed in the Johnson R filter. Our data
support the presence of a circum(sub)stellar disk around the young accreting
BD. Our data also support a grain growth in the submicron regime in the visible
photosphere of J0036+18 (1900 K). The polarimetric data do not obviously
correlate with activity or projected rotational velocity. Three polarized
early- to mid-L dwarfs display I-band light curves with amplitudes below 10
mmag.


title: Rotation and Disc Accretion in Very Low Mass Stars and Brown Dwarfs

abstract:
  The regulation of angular momentum is one of the key processes for our
understanding of stellar evolution. In contrast to solar-mass stars, very low
mass (VLM) objects and brown dwarfs are believed to be fully convective. This
may lead to major differences of rotation and activity, since fully convective
objects may not host a solar-type dynamo. Here, we report on our observational
efforts to understand the rotational evolution of VLM objects.


title: High-energy particle acceleration in the shell of a supernova remnant

abstract:
  A significant fraction of the energy density of the interstellar medium is in
the form of high-energy charged particles (cosmic rays). The origin of these
particles remains uncertain. Although it is generally accepted that the only
sources capable of supplying the energy required to accelerate the bulk of
Galactic cosmic rays are supernova explosions, and even though the mechanism of
particle acceleration in expanding supernova remnant (SNR) shocks is thought to
be well understood theoretically, unequivocal evidence for the production of
high-energy particles in supernova shells has proven remarkably hard to find.
Here we report on observations of the SNR RX J1713.7-3946 (G347.3-0.5), which
was discovered by ROSAT in the X-ray spectrum and later claimed as a source of
high-energy \gamma-rays of TeV energies (1 TeV=10^{12} eV). We present a TeV
\gamma-ray image of the SNR: the spatially resolved remnant has a shell
morphology similar to that seen in X-rays, which demonstrates that
very-high-energy particles are accelerated there. The energy spectrum indicates
efficient acceleration of charged particles to energies beyond 100 TeV,
consistent with current ideas of particle acceleration in young SNR shocks.


title: A Multiband Approach to AGN: Radioscopy & Radio Astronomy

abstract:
  Only in the radio-loud population of active galactic nuclei (AGN) does the
production, collimation, and acceleration of powerful relativistic jets take
place. We introduce here a concept of combined VLBI- and X-ray spectroscopic
observations of sources with relativistic, broad iron lines. This approach has
enormous potential to yield deep insights into the accretion/jet-production
process in AGN. Better knowledge of the milliarcsecond-resolution radio
structure of the nuclear radio cores in so-called ``radio-quiet''
broad-iron-line Seyfert galaxies is essential for future combined radio/X-ray
studies of the different modes of radio-jet production in accreting black hole
systems.


title: An XMM-Newton view of M101 - II. Global X-ray source properties

abstract:
  We present the global X-ray properties of the point source population in the
grand-design spiral galaxy M101, as seen with XMM-Newton. 108 X-ray sources are
detected within the D25 ellipse of M101, of which ~24 are estimated to be
background sources. Multiwavelength cross-correlations show that 20 sources are
coincident with HII regions and/or supernova remnants (SNRs), 7 have
identified/candidate background galaxy counterparts, 6 are coincident with
foreground stars and one has a radio counterpart. We apply an X-ray colour
classification scheme to split the source population into different types.
Approximately 60 per cent of the population can be classified as X-ray binaries
(XRBs), although there is source contamination from background AGN in this
category as they have similar spectral shapes in the X-ray regime. Fifteen
sources have X-ray colours consistent with supernova remnants (SNRs), three of
which correlate with known SNR/HII radio sources. We also detect 14 candidate
supersoft sources, with significant detections in the softest X-ray band (0.3-1
keV) only. Sixteen sources display short-term variability during the XMM-Newton
observation, twelve of which fall into the XRB category, giving additional
evidence of their accreting nature. Using archival Chandra & ROSAT HRI data, we
find that ~40 per cent of the XMM sources show long-term variability over a
baseline of up to ~10 years, and eight sources display potential transient
behaviour between observations. Sources with significant flux variations
between the XMM and Chandra observations show a mixture of softening and
hardening with increasing luminosity. The spectral and timing properties of the
sources coincident with M101 confirm that its X-ray source population is
dominated by accreting XRBs (abridged).


title:
The RASS-SDSS Galaxy Cluster Survey. III. Scaling relations of galaxy
  clusters

abstract:
  We use the RASS-SDSS galaxy cluster sample to compare the quality of optical
and X-ray luminosities as predictors of other cluster properties such as their
masses, temperatures, and velocity dispersions. We use the SDSS spectroscopic
data to estimate the velocity dispersions and the virial masses of a subsample
of 69 clusters within r_{500} and r_{200}. The ASCA temperature of the
intra-cluster medium, T_X, is retrieved from the literature for a subsample of
49 clusters. For this subsample we estimate the cluster masses also by using
the mass-temperature relation. We show that the optical luminosity, L_{op},
correlates with the cluster mass much better than the X-ray luminosity, L_X.
L_{op} can be used to estimate the cluster mass with an accuracy of 40% while
L_X can predict the mass only with a 55% accuracy. We show that correcting
$L_X$ for the effect of a cool core at the center of a cluster, lowers the
scatter of the $L_X-M$ relation only by 3%. We find that the scatter observed
in the L_{op}-L_X relation is determined by the scatter of the L_X-M relation.
The mass-to-light ratio in the SDSS i band clearly increases with the cluster
mass with a slope 0.2\pm0.08. The optical and X-ray luminosities correlate in
excellent way with both T_X and \sigma_V with an orthogonal scatter of 20% in
both relations. Moreover, L_{op} and L_X can predict with the same accuracy
both variables. We conclude that the cluster optical luminosity is a key
cluster parameter since it can give important information about fundamental
cluster properties such as the mass, the velocity dispersion, and the
temperature of the intra-cluster medium.


title: Modelling the red halos of blue compact galaxies

abstract:
  Optical/near-IR broadband photometry of the halos of blue compact galaxies
(BCGs) have revealed a very red spectral energy distribution, which cannot
easily be reconciled with any normal, metal-poor stellar population. Here,
three possible explanations for the red excess are explored: nebular emission,
metal-rich stars and a stellar population with a very bottom-heavy initial mass
function (IMF). We find, that nebular emission in BCG halos would produce very
blue near-IR colours, and hence fails to explain the observed red excess.
Although metal-rich stars may in principle explain the colours observed, the
required stellar metallicity is very high (solar or higher), which would be a
curious halo property given the low gas metallicity (~10% solar) of the central
starburst in these objects. A stellar population with a low to intermediate
metallicity and a very bottom-heavy IMF does however adequately reproduce the
observed BCG halo colours. A bottom-heavy IMF also proves successful in
explaining a similar red excess observed in the halos of stacked edge-on disk
galaxies from the Sloan Digital Sky Survey. This may indicate that halos
dominated by low-mass stars is a phenomenon common to galaxies of very
different Hubble types.


title: Strangelet propagation and cosmic ray flux

abstract:
  The galactic propagation of cosmic ray strangelets is described and the
resulting flux is calculated for a wide range of parameters as a prerequisite
for strangelet searches in lunar soil and with an Earth orbiting magnetic
spectrometer, AMS-02. While the inherent uncertainties are large, flux
predictions at a measurable level are obtained for reasonable choices of
parameters if strange quark matter is absolutely stable. This allows a direct
test of the strange matter hypothesis.


title:
Determination of stellar rotation with Gaia and effects of spectral
  mismatch

abstract:
  Stellar spectra obtained with Radial Velocity Spectrometer on-board Gaia will
enable determination of projected rotational velocities (v sin i) from
rotational broadening of spectral lines. To estimate the accuracy with which v
sin i can be determined for different stellar types and as a function of
magnitude, we perform simulations in which "observed" spectra (as obtained from
Gaia RVS simulator) are fitted with Kurucz spectra from template library using
the least square method. We compare results on the v sin i accuracy as obtained
in the case of spectra differing only in v sin i and in the case of a more
general spectral mismatch (in T_eff, log g, [Fe/H]).


title: Dynamical streams in the solar neighbourhood

abstract:
  The true nature of the Hyades and Sirius superclusters is still an open
question. In this contribution, we confront Eggen's hypothesis that they are
cluster remnants with the results of a kinematic analysis of more than 6000 K
and M giants in the solar neighbourhood. This analysis includes new radial
velocity data from a large survey performed with the Coravel spectrometer,
complemented by Hipparcos parallaxes and Tycho-2 proper motions (Famaey et al.
2004). A maximum-likelihood method, based on a bayesian approach, has been
applied to the data, in order to make full use of all the available data
(including less precise parallaxes) and to derive the properties of the
different kinematic subgroups. Two such subgroups can be identified with the
Hyades and Sirius superclusters. Stars belonging to them span a very wide range
of age, which is difficult to account for in Eggen's scenario. These groups are
thus most probably "dynamical streams" related to the dynamical perturbation by
spiral waves rather than to cluster remnants.
  In this scenario, the Hyades and Ursa Major clusters just happen to be in the
Hyades and Sirius streams, which are purely dynamical features that have
nothing to do with the remnants of more massive primordial clusters. This
mechanism could be the key to understanding the presence of an old metal-rich
population, and of many exoplanetary systems in our neighbourhood. Moreover, a
strong spiral pattern seems to be needed in order to yield such prominent
streams. Since spiral structure is usually baryonic, this would leave very
little room for dark matter. This may be an indication that the era of the
dark-matter paradigm explaining the dynamics of the Galaxy may come to an end,
and is being superseded by modified gravity.


title:
A family of models of partially relaxed stellar systems II. Comparison
  with the products of collisionless collapse

abstract:
  [Abridged] N-body simulations of collisionless collapse have offered
important clues to the construction of realistic stellar dynamical models of
elliptical galaxies. Understanding this idealized and relatively simple
process, by which stellar systems can reach partially relaxed equilibrium
configurations (characterized by isotropic central regions and radially
anisotropic envelopes), is a prerequisite to more ambitious attempts at
constructing physically justified models of elliptical galaxies in which the
problem of galaxy formation is set in the generally accepted cosmological
context of hierarchical clustering.
  In a previous paper, we have discussed the dynamical properties of a family
of models of partially relaxed stellar systems (the f^{(\nu)} models), designed
to incorporate the qualitative properties of the products of collisionless
collapse at small and at large radii. Here we revisit the problem of incomplete
violent relaxation, by making a direct comparison between the detailed
properties of such family of models and those of the products of collisionless
collapse found in N-body simulations that we have run for the purpose.
Surprisingly, the models thus identified are able to match the simulated
density distributions over nine orders of magnitude and also to provide an
excellent fit to the anisotropy profiles and a good representation of the
overall structure in phase space.


title: What fraction of stars formed in infrared galaxies at high redshift?

abstract:
  Star formation happens in two types of environment: ultraviolet-bright
starbursts (like 30 Doradus and HII galaxies at low redshift and Lyman-break
galaxies at high redshift) and infrared-bright dust-enshrouded regions (which
may be moderately star-forming like Orion in the Galaxy or extreme like the
core of Arp 220). In this work I will estimate how many of the stars in the
local Universe formed in each type of environment, using observations of
star-forming galaxies at all redshifts at different wavelengths and of the
evolution of the field galaxy population.


title:
The Optical Gravitational Lensing Experiment. Planetary and
  Low-Luminosity Object Transits in the Fields of Galactic Disk. Results of the
  2003 OGLE Observing Campaigns

abstract:
  We present results of two observing campaigns conducted by the OGLE-III
survey in the 2003 observing season aiming at the detection of new objects with
planetary transiting companions. Six fields of 35'x35' each located in the
Galactic disk were monitored with high frequency for several weeks in February
- July 2003. Additional observations of three of these fields were also
collected in the 2004 season. Altogether about 800 and 1500 epochs were
collected for the fields of both campaigns, respectively.
  The search for low depth transits was conducted on about 230000 stars with
photometry better than 15 mmag. It was focused on detection of planetary
companions, thus clear non-planetary cases were not included in the final list
of selected objects. Altogether we discovered 40 stars with shallow (<0.05 mag)
flat-bottomed transits. In each case several individual transits were observed
allowing determination of photometric elements. Additionally, the lower limits
on radii of the primary and companion were calculated. From the photometric
point of view the new OGLE sample contains many very good candidates for
extrasolar transiting planets. However, only the future spectroscopic follow-up
observations of the OGLE sample - determination of the amplitude of radial
velocity and exclusion of blending possibilities - may allow to confirm their
planetary status. In general, the transiting objects may be extrasolar planets,
brown dwarfs, M-type dwarfs or fake transits caused by blending. All
photometric data of objects with transiting companions discovered during the
2003 campaigns are available to the astronomical community from the OGLE
Internet archive.


title:
1E 1740.7-2942: temporal and spectral evolution from INTEGRAL and RXTE
  observations

abstract:
  We present results of the monitoring of the black hole candidate 1E
1740.7-2942 with INTEGRAL, in combination with simultaneous observations by
RXTE. We concentrate on broad-band spectra from INTEGRAL/IBIS and RXTE/PCA
instruments. During our observations, the source spent most of its time in the
canonical low/hard state with the measured flux variation within a factor of
two. In 2003 September the flux started to decline and in 2004 February it was
below the sensitivity level of the INTEGRAL and RXTE instruments. Notably,
during the decline phase the spectrum changed, becoming soft and typical of
black hole binaries in the intermediate/soft state.


title: Diffuse Cosmic Neutrino Background from Population III Stars

abstract:
  We study the expected diffuse cosmic neutrino flux produced by Population III
(PopIII) stars during their nuclear burning phases as well as from their final
stages of evolution (core collapse). Assuming a fraction f_III=10^(-3) of all
baryons forms PopIII stars, our flux estimate is comparable to the diffuse
neutrino flux produced by the ordinary stars and by the ordinary core-collapse
supernovae in the universe, i.e. of order 1-10 cm^(-2) s^(-1). Due to the large
cosmic redshift, however, the typical energies are in the MeV and sub-MeV range
where the solar and geophysical neutrino fluxes are much larger. A direct
detection of the diffuse cosmic flux is out of the question with presently
known experimental techniques.


title: On the discrete nature of the Red Giant Branch of omega Centauri

abstract:
  We report the results of an extensive VLT high-resolution imaging campaign of
the central region of the giant globular cluster omega Centauri. More than
100,000 stars have been measured in the inner 9'x 9' region of the cluster. On
the basis of multiband Colour Magnitude Diagrams (CMD), we confirm the
existence of multiple stellar populations along the Red Giant Branch (RGB).
Moreover, thanks to the high-precision of this dataset, we conclude that the
RGB does not present a smooth and continuous distribution, but shows a discrete
structure: besides the metal-poor and the extreme metal-rich population
(RGB-a), the existence of three metal intermediate populations is shown.


title: Discovery of X-ray pulsations from IGR J16320-4751 = AX J1631.9-4752

abstract:
  We report a discovery of strong modulations of the X-ray flux detected from
IGR J16320-4751 = AX J1631.9-4752 with a period of P~1300 sec. We reanalyzed
the data of an XMM-Newton ToO performed soon after the discovery of the source
by INTEGRAL and found the modulation at a period of P=1309+/-40 sec with a high
significance. Modulations of the source flux with two possible periods of ~1300
and ~1500 sec were identified in the ASCA archival data. It is very likely that
the modulation can be interpreted as X-ray pulsations, favouring a pulsar as
the compact object in IGR/AX J16320-4752. Thus for the moment this source
became the fourth source from a new class of highly absorbed binary systems for
which the pulsations are observed.


title:
Intrinsically faint quasars: evidence for meV axion dark matter in the
  Universe

abstract:
  Growing amount of observations indicate presence of intrinsically faint
quasar subgroup (a few % of known quasars) with noncosmological quantized
redshift. Here we find an analytical solution of Einstein equations describing
bubbles made from axions with periodic interaction potential. Such particles
are currently considered as one of the leading dark matter candidate. The
bubble interior possesses equal gravitational redshift which can have any value
between zero and infinity. Quantum pressure supports the bubble against
collapse and yields states stable on the scale more then hundreds million
years. Our results explain the observed quantization of quasar redshift and
suggest that intrinsically faint point-like quasars associated with nearby
galaxies are axionic bubbles with masses 10^8-10^9M_{Sun} and radii
10^3-10^4R_{Sun}. They are born in active galaxies and ejected into surrounding
space. Properties of such quasars unambiguously indicate presence of axion dark
matter in the Universe and yield the axion mass \approx 1 meV, which fits in
the open axion mass window constrained by astrophysical and cosmological
arguments.


title: Substructure and Tidal Debris in Local Galaxies: Models and Observations

abstract:
  One of the generic predictions of modern cosmological models is that large
galaxies should have experienced many mergers with smaller galaxies at some
point in their past. Debris from such encounters will leave spatially distinct
substructure in the stellar haloes of nearby galaxies, detectable for a few
orbital periods after the final merger. In the case of the Milky Way, kinematic
data from surveys such as RAVE and satellite missions such as GAIA will allow
us to probe much more of the merger history, and to connect the properties of
the stellar halo with those of local dwarf galaxies. To estimate what these
programmes may discover, we review current observations of minor mergers in
nearby galaxies, and compare these with predictions from a semi-analytic model
of galaxy formation.


title:
INTEGRAL insight into the inner parts of the Galaxy. High mass X-ray
  binaries

abstract:
  Since its launch INTEGRAL has devoted a significant fraction of its observing
time to the Galactic plane region. We present the results of INTEGRAL
observations of the inner spiral arms of the Galaxy (Norma, Scutum and
Sagittarius) with attention to high mass X-ray binaries. The increased
sensitivity of the survey and possibility to detect absorbed sources
significantly enlarged our sample of HMXBs in comparison with previous studies.
For some absorbed sources we present for the first time high quality broadband
(1-100 keV) energy spectra. We confirm pulsations of the X-ray flux of IGR
J16358-4726, discovered by CHANDRA, and report discovery of pulsations with a
period of $228\pm6$ sec from IGR J16465-4507. We confirm that the Galactic high
mass X-ray binary distribution is significantly different from the distribution
of low mass X-ray binaries concentrated in the Galactic Center. A large
fraction of detected high mass X-ray binaries are absorbed sources.


title:
Variable Linear Polarization from Sagittarius A*: Evidence for a Hot
  Turbulent Accretion Flow

abstract:
  We report the discovery of variability in the linear polarization from the
Galactic Center black hole source, Sagittarius A*. New polarimetry obtained
with the Berkeley-Illinois-Maryland Association array at a wavelength of 1.3 mm
shows a position angle that differs by 28 +/- 5 degrees from observations 6
months prior and then remains stable for 15 months. This difference may be due
to a change in the source emission region on a scale of 10 Schwarzschild radii
or due to a change of 3 x 10^5 rad m^-2 in the rotation measure. We consider a
change in the source physics unlikely, however, since we see no corresponding
change in the total intensity or polarized intensity fraction. On the other
hand, turbulence in the accretion region at a radius ~ 10 to 1000 R_s could
readily account for the magnitude and time scale of the position angle change.


title:
The Nonlinear Cosmological Matter Power Spectrum with Massive Neutrinos
  I: The Halo Model

abstract:
  Measurements of the linear power spectrum of galaxies have placed tight
constraints on neutrino masses. We extend the framework of the halo model of
cosmological nonlinear matter clustering to include the effect of massive
neutrino infall into cold dark matter (CDM) halos. The magnitude of the effect
of neutrino clustering for three degenerate mass neutrinos with m_nu=0.9 eV is
of order ~1%, within the potential sensitivity of upcoming weak lensing
surveys. In order to use these measurements to further constrain--or eventually
detect--neutrino masses, accurate theoretical predictions of the nonlinear
power spectrum in the presence of massive neutrinos will be needed, likely only
possible through high-resolution multiple particle (neutrino, CDM and baryon)
simulations.


title:
Heating a Distant Galaxy Cluster by Giant X-ray Cavities and Large-Scale
  Shock Fronts

abstract:
  We report the discovery of a pair of giant cavities, each nearly 200 kpc in
diameter, embedded in the gaseous halo of the redshift z=0.216 galaxy cluster
MS0735.6+7421. The cavities appear as surface brightness depressions in an
image of the cluster taken with the Chandra X-ray Observatory. The X-ray
cavities are filled with radio emission and are bounded by an elliptical shock
structure resembling a ``radio cocoon.'' The shock's energy and age, ~6E61 erg
and ~100 Myr, respectively, give a time averaged power of ~1.7E46 erg/s, making
it the most powerful radio outburst known. The outburst is apparently heating
the cluster by 1/3 keV per particle, which is sufficient to quench a large
cooling flow for several Gyr and to supply a substantial fraction of the energy
required to "preheat" the cluster. If the outburst was powered by accretion
onto a supermassive black hole, more than 3E8 solar masses of material would be
required to do so. This implies that the putative supermassive black hole lying
at the center of the cD galaxy has accreted a substantial fraction of its own
mass in less than 100 Myr.


title:
Opacity Variations in the Ionized Absorption in NGC 3783: A Compact
  Absorber

abstract:
  We show that the Fe (VII-XII) M-shell unresolved transition array (UTA) in
the NGC 3783 900 ks Chandra HETGS observation clearly changes in opacity in a
timescale of 31 days responding to a factor of 2 change in the ionizing
continuum. The opacity variation is observed at a level >10 sigma. There is
also evidence for variability in the O VI K edge (at 3 sigma level). The
observed changes are consistent with the gas producing these absorption
features (the low ionization component) being close to photoionization
equilibrium. The gas responsible for the Fe (XVII-XXII) L-shell absorption (the
high ionization component), does not seem to be responding as expected in
photoionization equilibrium. The observed change in opacity for the UTA implies
a density >1E4 cm-3, and so locates the gas within 6 pc of the X-ray source.
The scenario in which the gas is composed of a continuous radial range of
ionization structures is ruled out, as in such scenario, no opacity variations
are expected. Rather, the structure of the absorber is likely composed by
heavily clumped gas.


title: The component masses of the cataclysmic variable V347 Puppis

abstract:
  We present time-resolved spectroscopy and photometry of the double-lined
eclipsing cataclysmic variable V347 Pup (= LB 1800). There is evidence of
irradiation on the inner hemisphere of the secondary star, which we correct for
using a model to give a secondary star radial velocity of K_R = 198 \pm 5 km/s.
The rotational velocity of the secondary star in V347 Pup is found to be v sin
i = 131 \pm 5 km/s and the system inclination is i = 84.0 \pm 2.3 degrees. From
these parameters we obtain masses of M_1 = 0.63 \pm 0.04 M_\odot for the white
dwarf primary and M_2 = 0.52 \pm 0.06 M_\odot for the M0.5V secondary star,
giving a mass ratio of q = 0.83 \pm 0.05. On the basis of the component masses,
and the spectral type and radius of the secondary star in V347 Pup, we find
tentative evidence for an evolved companion. V347 Pup shows many of the
characteristics of the SW Sex stars, exhibiting single-peaked emission lines,
high-velocity S-wave components and phase-offsets in the radial velocity curve.
We find spiral arms in the accretion disc of V347 Pup and measure the disc
radius to be close to the maximum allowed in a pressureless disc.


title:
HST/NICMOS Imaging Polarimetry of Proto-Planetary Nebulae: Probing of
  the Dust Shell Structure via Polarized Light

abstract:
  Using NICMOS on HST, we have performed imaging polarimetry of proto-planetary
nebulae. Our objective is to study the structure of optically thin
circumstellar shells of post-asymptotic giant branch stars by separating
dust-scattered, linearly polarized star light from unpolarized direct star
light. This unique technique allows us to probe faint reflection nebulae around
the bright central star, which can be buried under the point-spread-function of
the central star in conventional imaging. Our observations and archival search
have yielded polarimetric images for five sources: IRAS 07134+1005 (HD 56126),
IRAS 06530-0213, IRAS 04296+3429, IRAS (Z)02229+6208, and IRAS 16594-4656.
These images have revealed the circumstellar dust distribution in an
unprecedented detail via polarized intensity maps, providing a basis to
understand the 3-D structure of these dust shells. We have observationally
confirmed the presence of the inner cavity caused by the cessation of AGB mass
loss and the internal shell structures which is strongly tied to the progenitor
star's mass loss history on the AGB. We have also found that equatorial
enhancement in these circumstellar shells comes with various degrees of
contrast, suggesting a range of optical depths in these optically thin shells.
Our data support the interpretation that the dichotomy of PPN morphologies is
due primarily to differences in optical depth and secondary to the inclination
effect. The polarization maps reveal a range of inclination angles for these
optically thin reflection nebulae, dispelling the notion that elliptical
nebulae are pole-on bipolar nebulae.


title: The Intermediate-Scale Clustering of Luminous Red Galaxies

abstract:
  We report the intermediate-scale (0.3 to 40 Mpc/h) clustering of 35,000
luminous early-type galaxies at redshifts 0.16 to 0.44 from the Sloan Digital
Sky Survey. We present the redshift-space two-point correlation function
\xi(s), the projected correlation function w_p(r_p), and the deprojected
real-space correlation function \xi(r), for approximately volume-limited
samples. As expected, the galaxies are highly clustered, with the correlation
length varying from 9.8 +/- 0.2 Mpc/h to 11.2 +/- 0.2 Mpc/h, dependent on the
specific luminosity range. For the -23.2 < Mg < -21.2 sample, the inferred bias
relative to that of L* galaxies is 1.84 +/- 0.11 for 1 Mpc/h < r_p < 10 Mpc/h,
with yet stronger clustering on smaller scales. We detect luminosity-dependent
bias within the sample but see no evidence for redshift evolution between z=0.2
and z=0.4. We find a clear indication for deviations from a power-law in the
real-space correlation function, with a dip at ~ 2 Mpc/h scales and an upturn
on smaller scales. The precision measurements of these clustering trends offer
new avenues for the study of the formation and evolution of these massive
galaxies.


title: The Number of Supernovae from Primordial Stars in the Universe

abstract:
  Recent simulations of the formation of the first luminous objects in the
universe predict isolated very massive stars to form in dark matter halos with
virial temperatures large enough to allow significant amounts of molecular
hydrogen to form. We construct a semi-analytic model based on the
Press-Schechter formalism and calibrate the minimum halos mass that may form a
primordial star with the results from extensive adaptive mesh refinement
simulations. The model also includes star formation in objects with virial
temperatures in excess of ten thousand Kelvin. The free parameters are tuned to
match the optical depth measurements by the WMAP satellite. The models
explicitly includes the negative feedback of the destruction of molecular
hydrogen by a soft UV background which is computed self-consistently. We
predict high redshift supernova rates as one of the most promising tools to
test the current scenario of primordial star formation. The supernova rate from
primordial stars peaks at redshifts ~20. Using an analytic model for the
luminosities of pair-instability supernovae we predict observable magnitudes
and discuss possible observational strategies. Such supernovae would release
enough metals corresponding to a uniform enrichment to a few hundred thousands
of solar metalicity. If some of these stars produce gamma ray bursts our rates
will be directly applicable to understanding the anticipated results from the
SWIFT satellite. This study highlights the great potential for the James Webb
space telescope in probing cosmic structure at redshifts greater than 20.


title:
The Small-scale Clustering of Luminous Red Galaxies via
  Cross-Correlation Techniques

abstract:
  We present the small-scale (0.2h^{-1} to 7h^{-1} Mpc) cross-correlations
between 32,000 luminous early-type galaxies and a reference sample of 16
million normal galaxies from the Sloan Digital Sky Survey. Our method allows us
to construct the spherically averaged, real-space cross-correlation function
between the spectroscopic LRG sample and galaxies from the SDSS imaging. We
report the cross-correlation as a function of scale, luminosity, and redshift.
We find very strong luminosity dependences in the clustering amplitudes, up to
a factor of 4 over a factor of 4 in luminosity, and measure this dependence
with high signal-to-noise ratio. The luminosity dependence of bias is found to
depend on scale, with more variation on smaller scales. The clustering as a
function of scale is not a power law, but instead has a dip at 1h^{-1} Mpc and
an excess on small scales. The fraction of red galaxies within the L* sample
surrounding LRGs is a strong function of scale, as expected. However, the
fraction of red galaxies evolves in redshift similarly on small and large
scales, suggesting that cluster and field populations are changing in the same
manner. The results highlight the advantage on small scales of using
cross-correlation methods as a means of avoiding shot noise in samples of rare
galaxies.


title: A Hot Water Bottle for Aging Neutron Stars

abstract:
  The gapless color-flavor locked (gCFL) phase is the second-densest phase of
matter in the QCD phase diagram, making it a plausible constituent of the core
of neutron stars. We show that even a relatively small region of gCFL matter in
a star will dominate both the heat capacity C_V and the heat loss by neutrino
emission L_\nu. The gCFL phase is characterized by an unusual quasiparticle
dispersion relation that makes both its specific heat c_V and its neutrino
emissivity epsilon_\nu parametrically larger than in any other phase of nuclear
or quark matter. During the epoch in which the cooling of the star is dominated
by direct Urca neutrino emission, the presence of a gCFL region does not
strongly alter the cooling history because the enhancements of C_V and L_\nu
cancel against each other. At late times, however, the cooling is dominated by
photon emission from the surface, so L_\nu is irrelevant, and the anomalously
large heat capacity of the gCFL region keeps the star warm. The temperature
drops with time as T\sim t^{-1.4} rather than the canonical T\sim t^{-5}. This
provides a unique and potentially observable signature of gCFL quark matter.


title:
Massive HI clouds with no optical counterparts as high-density regions
  of intragroup HI rings and arcs

abstract:
  We present a new scenario in which massive intragroup HI clouds are the
high-density parts of large HI rings/arcs formed by dynamical interaction
between galaxy groups and gas-rich, low surface brightness (LSB) galaxies with
extended gas disks. Our hydrodynamical simulations demonstrate that the group
tidal field is very efficient at stripping the outer HI gas of the disk if the
gaseous disk of the LSB galaxy extends $2 - 5$ times further than the stellar
disk. We find that a massive, extended `leading stream' orbiting the group's
center can form out of the stripped outer HI envelope, while the severely
shrunk LSB galaxy, whose stellar disk remains unaffected, continues on its
path. The result is a relatively isolated, massive HI cloud with a ring- or
arc-like shape, a very inhomogeneous density distribution ($N_{\rm HI} \sim 1.0
\times 10^{17} - 1.1 \times 10^{20}$ atoms cm$^{-2}$), and, initially, no
stellar content. Only the high density peaks of the simulated intragroup HI
ring/arc can be detected in many current HI observations. These will appear as
relatively isolated `HI islands' near the group center. We also find that star
formation can occur within the ring/arc, if the total gas mass within the
intragroup ring/arc is very large ($\sim$ 4 $\times$ $10^9$ ${\rm M}_{\odot}$).
We discuss these results in terms of existing observations of intragroup gas
(e.g., the Leo Ring and HIPASS J0731--69) and intergalactic HII regions.


title: Fe K emission in the ultraluminous infrared galaxy Arp220

abstract:
  Prominent Fe K line emission is detected at around 6.7 keV in the XMM-Newton
spectrum of the ultraluminous infrared galaxy Arp220. The continuum emission in
the 2.5-10 keV band is flat and a few other spectral features are suggested.
The large EW of the Fe K line poses a problem with interpreting the hard X-ray
emission as integrated X-ray binary emission. A thermal emission spectrum with
a temperature of kT~7 keV modified by some absorption, which would be expected
from an internally shocked hot bubble in a starburst region, can describe the
spectrum. An ensemble of radio supernovae in a dense environment, as suggested
from VLBI imaging, could be another possibility, if frequent occurence of such
powerful supernovae is sustained. However, the apparent lack of X-ray binary
emission does not match the high supernova rate required by both
interpretations. Highly photoionized, low-density gas illuminated by a hidden
Compton-thick AGN is a possible alternative, which can be tested by
presence/absence of radiative recombination continua in better quality data
expected from a forthcoming observation.


title: Probing the Type Ia environment with Light Echoes

abstract:
  In general, Light Echoes (LE) are beautiful, rather academical and therefore
unavoidably useless phenomena. In some cases, however, they can give
interesting information about the environment surrounding the exploding star.
After giving a brief introduction to the subject, I describe its application to
the case of Type Ia Supernovae and discuss the implications for progenitors and
their location within the host galaxies.


title: A general catalogue of 6.7 GHz methanol masers. I: data

abstract:
  Methanol masers are often detected in regions of intense star formation.
Several studies in the last decade indicate that they may even be the earliest
signpost of a high-mass star-forming region. Their powerful emission make them
very good candidates for observations using both single--dish telescopes and
interferometers, the latter allows detailed structural and dynamical studies of
these objects. We have prepared a catalogue of all known 6.7-GHz methanol
masers, discovered both by surveys that targeted possible associated objects
and unbiased surveys covering a large fraction of galactic longitudes across
the Galactic plane (-0.5deg <= b <= 0.5deg for most of the regions). The
catalogue contains 519 sources which are listed with their kinematic
(galactocentric and heliocentric) distances as well as possibly associated IR
objects. We find that 6.7-GHz methanol masers clearly trace the molecular ring
of our Galaxy, where most of the OB associations are located. The present list
of masers also reports detections of other masing transitions of methanol as
further information for the study of the maser phenomenon. In a further
publication we will address some statistical considerations.


title: INTEGRAL and XMM-Newton Observations of GRB040106

abstract:
  On January 6th 2004, the IBAS burst alert system triggered the 8th gamma-ray
burst (GRB) to be located by the INTEGRAL satellite. The position was
determined and publicly distributed within 12s, prompting ESA's XMM-Newton to
execute a ToO observation just 5 hours later, during which an X-ray afterglow
was detected. The GRB had a duration ~52s with two distinct pulses separated by
\~42s. Here we present the results of imaging and spectral analyses of the
prompt emission from INTEGRAL data and the X-ray afterglow from XMM-Newton
data. The gamma-ray spectrum is consistent with a single power-law of photon
index -1.72 +/- 0.15. The fluence (20-200 keV) was 8.2 x 10^-7 erg cm^-2. The
X-ray afterglow (F_nu (t) propto nu^-beta_X t^-delta) was extremely hard with
beta_X = 0.47 +/- 0.01 and delta = 1.46 +/- 0.04. The 2-10 keV flux 11 hours
after the burst was 1.1 x 10^-12 erg cm^-2 s^-1. The time profile of the GRB is
consistent with the observed trends from previous analysis of BATSE GRBs. We
find that the X-ray data are not well-fit by either a simple spherical fireball
or by a speading jet, expanding into a homogeneous medium or a wind
environment. Based on previously determined correlations between GRB spectra
and redshift, we estimate a redshift of ~0.9^+0.5_-0.4 (1 sigma) and a lower
limit on the isotropic radiated energy of ~5 x 10^51 erg in this burst.


title:
High velocity features in the spectra of the Type Ia SN 1999ee: a
  property of the explosion or evidence of circumstellar interaction?

abstract:
  The near-maximum spectra of the Type Ia SN 1999ee are reviewed. Two narrow
absorption features corresponding to the strongest component of the CaII IR
triplet appear in the spectra from 7 days before to 2 days after B-band
maximum, at a high velocity (~22,000 km/s). Before these features emerge, the
CaII IR triplet has an anomalously high velocity, indicating that the narrow
features were still blended with the main, photospheric component.
High-velocity CaII absorption has been observed in other SNe Ia, but usually
detached from the photospheric component. Furthermore, the SiII 6355A line is
observed at a comparably high velocity (~20,000 km/s) 9 and 7 days before B
maximum, but then it suddenly shifts to much lower velocities. Synthetic
spectra are used to reproduce the data under various scenarios. An abundance
enhancement requires an outer region dominated by Si and Ca, the origin of
which is not easy to explain in terms of nuclear burning. A density enhancement
leads to a good reproduction of the spectral evolution if a mass of ~0.10 Msun
is added at velocities between 16,000 and 28,000 km/s, and it may result from a
perturbation, possibly angular, of the explosion. An improved match to the CaII
IR triplet at the earliest epoch can be obtained if the outermost part of this
modified density profile is assumed to be dominated by H (~0.004 Msun above
24,000 km/s). Line broadening is then the result of increased electron
scattering. This H may be the result of interaction between the ejecta and
circumstellar material.


title:
Limits on the detectability of the CMB B-mode polarization imposed by
  foregrounds

abstract:
  We investigate which practical constraints are imposed by foregrounds to the
detection of the B-mode polarization generated by gravitational waves in the
case of experiments of the type currently being planned. Because the B-mode
signal is probably dominated by foregrounds at all frequencies, the detection
of the cosmological component depends drastically on our ability for removing
foregrounds. We provide an analytical expression to estimate the level of the
residual polarization for Galactic foregrounds, according to the method
employed for their subtraction. We interpret this result in terms of the lower
limit of the tensor-to-scalar ratio r that allows to disentangle the
cosmological B-mode polarization from the foregrounds contribution. Polarized
emission from extragalactic radio sources and gravitational lensing is also
taken into account. As a first approach, we consider the ideal limit of an
instrumental noise--free experiment: for a full--sky coverage and a degree
resolution, we obtain a limit of r~10^(-4). This value can be improved by
high--resolution experiments and, in principle, no clear fundamental limit on
the detectability of gravitational waves polarization is found. Our analysis is
also applied to planned or hypothetical future polarization experiments, taking
into account expected noise levels.


title:
Does dichotomy of active galactic nuclei only depend on black hole
  spins?

abstract:
  A toy model for jet powers and radio loudness of active galactic nuclei
(AGNs) is proposed based on the coexistence of the Blandford-Znajek (BZ) and
magnetic coupling (MC) processes (CEBZMC) in black hole (BH) accretion disc. It
turns out that both the jet powers and radio-loudness of AGNs are controlled by
more than one physical parameter besides the BH spin. The observed dichotomy
between radio-loud and radio-quiet AGNs is well interpreted by the two
parameters, the BH spin and the power-law index of the variation of the
magnetic field on the disc. Furthermore, we discuss the correlation of jet
powers with radio loudness of AGNs in terms of the two parameters. It is found
that the contours of radio loudness are approximately in accord with those of
jet powers for several 3CR radio sources, implying roughly that the stronger
jet power corresponds to stronger radio loudness. In addition we discuss the
correlation of the jet powers and radio-loudness of AGNs with the position of
the inner edge of an accretion disc. These results imply that the spin paradigm
for radio loudness of AGNs might be modified by a scenario containing more
physical parameters.


title: Li, Be, B and Cosmic Rays in the Galaxy

abstract:
  A short overview is presented of current issues concerning the production and
evolution of Li, Be and B in the Milky Way. It is argued that the currently
popular idea that Galactic cosmic rays are accelerated inside metal-rich
superbubbles (which leads ``naturally'' to the production of primary Be and B,
as observed) encounters the same problems as the previously popular idea of
supernovae accelerating their own ejecta. A major challenge to theories of
light element production is presented by the recent (and still preliminary)
data suggesting a surprisingly high and $\sim$constant abundance of $^6$Li in
halo stars; attempts to explain such a ``plateau'' are critically examined.


title:
Rotational period of WD1953-011 - a magnetic white dwarf with a star
  spot

abstract:
  WD1953-011 is an isolated, cool (7920 +/- 200K, Bergeron, Legget & Ruiz,
2001) magnetic white dwarf (MWD) with a low average field strength (~70kG,
Maxted et al. 2000) and a higher than average mass (~0.74 M_sun, Bergeron et
al. 2001). Spectroscopic observations taken by Maxted et al. (2000) showed
variations of equivalent width in the Balmer lines, unusual in a low field
white dwarf. Here we present V band photometry of WD1953-011 taken at 7 epochs
over a total of 22 months. All of the datasets show a sinusoidal variation of
approximately 2% peak-to-peak amplitude. We propose that these variations are
due to a star spot on the MWD, analogous to a sunspot, which is affecting the
temperature at the surface, and therefore its photometric magnitude. The
variations have a best-fit period over the entire 22 months of 1.4418 days,
which we interpret as the rotational period of the WD.


title:
Inferring coronal structure from X-ray lightcurves and Doppler shifts: a
  Chandra study of AB Doradus

abstract:
  The Chandra X-ray observatory monitored the single cool star, AB Doradus,
continuously for a period lasting 88 ksec (1.98 Prot) in 2002 December with the
LETG/HRC-S. The X-ray lightcurve shows rotational modulation, with three peaks
that repeat in two consecutive rotation cycles. These peaks may indicate the
presence of compact emitting regions in the quiescent corona. Centroid shifts
as a function of phase in the strongest line profile, O VIII 18.97 A, indicate
Doppler rotational velocities with a semi-amplitude of 30 +/- 10 km/s. By
taking these diagnostics into account along with constraints on the rotational
broadening of line profiles (provided by archival Chandra HETG Fe XVII and FUSE
Fe XVIII profile) we can construct a simple model of the X-ray corona that
requires two components. One of these components is responsible for 80% of the
X-ray emission, and arises from the pole and/or a homogeneously distributed
corona. The second component consists of two or three compact active regions
that cause modulation in the lightcurve and contribute to the O VIII centroid
shifts. These compact regions account for 16% of the emission and are located
near the stellar surface with heights of less than 0.3R*. At least one of the
compact active regions is located in the partially obscured hemisphere of the
inclined star, while one of the other active regions may be located at 40
degrees. High quality X-ray data such as these can test the models of the
coronal magnetic field configuration as inferred from magnetic Zeeman Doppler
imaging.


title:
The Phoenix Deep Survey: the clustering and the environment of Extremely
  Red Objects

abstract:
  In this paper we explore the clustering properties and the environment of the
Extremely Red Objects (EROs; I-K>4mag) detected in a ~180arcmin^2 deep
(Ks~20mag) Ks-band survey of a region within the Phoenix Deep Survey, an
on-going multiwavelength program aiming to investigate the nature and the
evolution of faint radio sources. Using our complete sample of 289 EROs
brighter than Ks=20mag we estimate a statistically significant (~3.7sigma)
angular correlation function signal with amplitude Aw=8.7^{+2.1}_{-1.7}x10^{-3}
consistent with earlier work based on smaller samples. This amplitude suggests
a clustering length in the range ro=12-17h^{-1}Mpc, implying that EROs trace
regions of enhanced density. Using a novel method we further explore the
association of EROs with galaxy overdensities by smoothing the K-band galaxy
distribution using the matched filter algorithm of Postman et al. (1996) and
then cross-correlating the resulting density maps with the ERO positions. Our
analysis provides direct evidence that EROs are associated with overdensities
at redshifts z>1. We also exploit the deep radio 1.4GHz data (limiting flux
60microJy) available to explore the association of EROs and faint radio sources
and whether the two populations trace similar large scale structures.
Cross-correlation of the two samples (after excluding 17EROs with radio
counterparts) gives a 2sigma signal only for the sub-sample of high-z radio
sources (z>0.6). Although the statistics are poor this suggests that it is the
high-z radio sub-sample that traces similar structures with EROs.


title: Relativistic Outflows form Active Galactic Nuclei

abstract:
  The current popular model for launching, accelerating and collimating
astrophysical jets is based on magnetohydrodynamics (MHD). AGN jets are most
probably powered by energy extracted from either an accretion disk or a rapidly
rotating Black Hole. Some progress in understanding accretion processes for
rotating Black Holes has been made: standard disks are truncated at some radius
depending on the accretion rate so that disk outflows are driven by the inner
hot advective disk. Slow outflows are the norm when the magnetorotational
instability is at work for the case of weak fields. In order to achieve Lorentz
factors of about 10, strong large-scale magnetic fields must thread the Black
Hole's ergosphere. The production of relativistic outflows is then understood
within stationary MHD models. In the collimated region, the electrons are
boosted to a non-thermal relativistic distribution, which is the basis of all
observations.


title: Feasibility study of a Laue lens for hard X-rays for space astronomy

abstract:
  We report on the feasibility study of a Laue lens for hard X-rays (>60
keV)based on mosaic crystals, for astrophysical applications. In particular we
discuss the scientific motivations, its functioning principle, the procedure
followed to select the suitable crystal materials, the criteria adopted to
establish crystal dimensions and their distribution on the lens in order to
obtain the best lens focusing capabilities, and the criteria for optimizing the
lens effective area in a given passband. We also discuss the effects of
misalignments of the crystal tiles due to unavoidable mechanical errors in
assembling the lens. A software was developed to face all these topics and to
evaluate the expected lens performance.


title: Embedded Clusters and the IMF

abstract:
  Despite valiant efforts over nearly five decades, attempts to determine the
IMF over a complete mass range for galactic field stars and in open clusters
have proved difficult. Infrared imaging observations of extremely young
embedded clusters coupled with Monte Carlo modeling of their luminosity
functions are improving this situation and providing important new
contributions to our fundamental knowledge of the IMF and its universality in
both space and time.


title:
N-body/SPH study of the evolution of dwarf galaxies in a cluster
  environment

abstract:
  Using an N-body/SPH code, we explore the scenario in which a dwarf elliptical
galaxy (dE) is subjected to ram-pressure stripping due to the intracluster
medium (ICM). Our simulations show that while (i) smaller dEs lose their ISM
almost immediately after entering the cluster, (ii) more massive dEs are able
to retain their gas for considerable timespans.


title: The Phoenix Deep Survey: Optical and near infrared imaging catalogs

abstract:
  The Phoenix Deep Survey is a multi-wavelength galaxy survey based on deep 1.4
GHz radio imaging (Hopkins et al., 2003). The primary goal of this survey is to
investigate the properties of star formation in galaxies and to trace the
evolution in those properties to a redshift z=1, covering a significant
fraction of the age of the Universe. By compiling a sample of star-forming
galaxies based on selection at radio wavelengths we eliminate possible biases
due to dust obscuration, a significant issue when selecting objects at optical
and ultraviolet wavelengths. In this paper, we present the catalogs and results
of deep optical (UBVRI) and near-infrared (Ks) imaging of the deepest region of
the existing decimetric radio imaging. The observations and data-processing are
summarised and the construction of the optical source catalogs described,
together with the details of the identification of candidate optical
counterparts to the radio catalogs. Based on our UBVRIKs imaging, photometric
redshift estimates for the optical counterparts to the radio detections are
explored.


title: The Phoenix Deep Survey: spectroscopic catalog

abstract:
  The Phoenix Deep Survey is a multi-wavelength survey based on deep 1.4 GHz
radio imaging, reaching well into the sub-100 microJy level. One of the aims of
this survey is to characterize the sub-mJy radio population, exploring its
nature and evolution. In this paper we present the catalog and results of the
spectroscopic observations aimed at characterizing the optically ``bright''
(R<~ 21.5 mag) counterparts of faint radio sources. Out of 371 sources with
redshift determination, 21% have absorption lines only, 11% show AGN
signatures, 32% are star-forming galaxies, 34% show narrow emission lines that
do not allow detailed spectral classification (due to poor signal-to-noise
ratio and/or lack of diagnostic emission lines) and the remaining 2% are
identified with stars. For the star-forming galaxies with a Balmer decrement
measurement we find a median extinction of A(Ha)=1.9 mag, higher than that of
optically selected samples. This is a result of the radio selection, which is
not biased against dusty systems. Using the available spectroscopic
information, we estimate the radio luminosity function of star-forming galaxies
in two independent redshift bins at z~0.1 and 0.3 respectively. We find direct
evidence for strong luminosity evolution of these systems consistent with L(1.4
GHz) ~ (1+z)^(2.7).


title:
Conformal models of de Sitter space, initial conditions for inflation
  and the CMB

abstract:
  Conformal embedding of closed-universe models in a de Sitter background
suggests a quantisation condition on the available conformal time. This
condition implies that the universe is closed at no greater than the 10% level.
When a massive scalar field is introduced to drive an inflationary phase this
figure is reduced to closure at nearer the 1% level. In order to enforce the
constraint on the available conformal time we need to consider conditions in
the universe before the onset of inflation. A formal series around the initial
singularity is constructed, which rests on a pair of dimensionless,
scale-invariant parameters. For physically-acceptable models we find that both
parameters are of order unity, so no fine tuning is required, except in the
mass of the scalar field. For typical values of the input parameters we predict
the observed values of the cosmological parameters, including the magnitude of
the cosmological constant. The model produces a very good fit to the most
recent CMBR data, predicting a low-l fall-off in the CMB power spectrum
consistent with that observed by WMAP.


title: 3-D Kinematics of the HH 110 jet

abstract:
  We present new results on the kinematics of the jet HH 110. New proper motion
measurements have been calculated from [SII] CCD images obtained with a time
baseline of nearly fifteen years. HH 110 proper motions show a strong asymmetry
with respect to the outflow axis, with a general trend of pointing towards the
west of the axis direction. Spatial velocities have been obtained by combining
the proper motions and radial velocities from Fabry-Perot data. Velocities
decrease by a factor ~3 over a distance of ~10$^{18}$ cm, much shorter than the
distances expected for the braking caused by the jet/environment interaction.
Our results show evidence of an anomalously strong interaction between the
outflow and the surrounding environment, and are compatible with the scenario
in which HH 110 emerges from a deflection in a jet/cloud collision.


title: Structured Query Language for Virtual Observatory

abstract:
  Currently two query languages are defined as standards for the Virtual
Observatory (VO). Astronomical Data Query Language (ADQL) is used for catalog
data query and Simple Image Access Protocol (SIAP) is for image data query. As
a result, when we query each data service, we need to know in advance which
language is supported and then construct a query language accordingly. The
construct of SIAP is simple, but they have a limited capability. For example,
there is no way to specify multiple regions in one query, and it is difficult
to specify complex query conditions. In this paper, we propose a unified query
language for any kind of astronomical database on the basis of SQL99. SQL is a
query language optimized for a table data, so to apply the SQL to the image and
spectrum data set, the data structure need to be mapped to a table like
structure. We present specification of this query language and an example of
the architecture for the database system.


title: H.E.S.S. Observations of PKS 2155-304

abstract:
  The high-frequency peaked BL Lac PKS 2155-304 at redshift z=0.117 has been
detected with high significance (~45 sigma) at energies greater than 160 GeV,
using the H.E.S.S. stereoscopic array of imaging air-Cherenkov telescopes in
Namibia. A strong signal is found in each of the data sets corresponding to the
dark periods of July and October, 2002, and June-September, 2003. The observed
flux of VHE gamma rays shows variability on time scales of months, days, and
hours. The monthly-averaged integral flux above 300 GeV varies between 10% and
60% of the flux observed from the Crab Nebula. Energy spectra are measured for
these individual periods of data taking and are characterized by a steep power
law with a time-averaged photon index of 3.32 +/- 0.06. An improved chi-square
per degree of freedom is found when either a power law with an exponential
cutoff energy or a broken power law are fit to the time-averaged energy
spectrum. However, the significance of the improvement is marginal (~2 sigma).
The suggested presence of features in the energy spectrum may be intrinsic to
the emission from the blazar, or an indication of absorption of TeV gamma rays
by the extragalactic infrared background light.


title:
Multi-Temperature Blackbody Spectrum of a Thin Accretion Disk around a
  Kerr Black Hole: Model Computations and Comparison with Observations

abstract:
  We use a ray-tracing technique to compute the observed spectrum of a thin
accretion disk around a Kerr black hole. We include all relativistic effects
such as frame-dragging, Doppler boost, gravitational redshift, and bending of
light by the gravity of the black hole. We also include self-irradiation of the
disk as a result of light deflection. Assuming that the disk emission is
locally blackbody, we show how the observed spectrum depends on the spin of the
black hole, the inclination of the disk, and the torque at the inner edge of
the disk. We find that the effect of a nonzero torque on the spectrum can, to a
good approximation, be absorbed into a zero-torque model by adjusting the mass
accretion rate and the normalization. We describe a computer model, called
KERRBB, which we have developed for fitting the spectra of black hole X-ray
binaries. Using KERRBB within the X-ray data reduction package XSPEC, and
assuming a spectral hardening factor f_col = 1.7, we analyze the spectra of
three black hole X-ray binaries: 4U1543-47, XTE J1550-564, and GRO J1655-40. We
estimate the spin parameters of the black holes in 4U1543-47 and GRO J1655-40
to be a/M ~ 0.6 and ~ 0.6-0.7, respectively. If f_col ~ 1.5-1.6, as in a recent
study, then we find a/M ~ 0.7-0.8 and ~ 0.8-0.9, respectively. These estimates
are subject to additional uncertainties in the assumed black hole masses,
distances and disk inclinations.


title: Multiwavelength Observations of Ultraluminous X-Ray Sources

abstract:
  Multiwavelength observations may help us understand the physical nature of
the ultraluminous X-ray sources (ULXs) found in external galaxies. Enabled by
the arcsecond X-ray source positions now available from Chandra, there has been
significant recent progress in the identification of optical and radio
counterparts to ULXs. Recent results are reviewed on the identification of
optical stellar counterparts to ULXs, the relation between ULXs and regions of
active star formation, the study of optical nebular counterparts to ULXs, and
the estimation of the luminosity of ULXs via their influence on surrounding
nebula.


title:
A Search for Low Mass Stars and Brown Dwarfs in the Upper Scorpius OB
  Association

abstract:
  We are conducting a U,B,R,I monitoring program to identify pre-main sequence
stars and brown dwarfs in a 12.5x12.2 square degree region of the Upper
Scorpius OB association (5-10 Myr). We will use these data in combination with
a follow-up spectroscopy survey to derive the low mass IMF in Upper Sco and to
explore the prevalence of 5-10 Myr circumstellar disks. We will also analyze
the spatial distribution of association members as a function of stellar mass,
from which we will be able to place constraints on brown dwarf formation
scenarios. We expect to identify 700-1800 previously unknown pre-main sequence
objects in Upper Sco with M < 0.6 M_Sun. This dataset will constitute the
largest sample known to date of stars/brown dwarfs at 5-10 Myr.


title: The Physics of Galaxy Clustering I: A Model for Subhalo Populations

abstract:
  (Abridged) We present a semi-analytic model for Cold Dark Matter halo
substructure that can be used as a framework for studying galaxy formation and
an ingredient in halo models of galaxy clustering. We perform a comprehensive
comparison of the model to the results of a suite of high-resolution
cosmological simulations. The comparisons reveal that subhalo statistics, such
as velocity and mass functions, radial distributions, and the halo occupation
distributions, agree well over three orders of magnitude in host halo mass at
various redshifts. Both in the simulations and in our model, the radial
distributions of subhalos are significantly shallower than that of the dark
matter density. The abundance of subhalos in a host is set by competition
between destruction and new accretion. High mass halos and halos at high
redshift tend to host more subhalos because the subhalos have, on average, been
accreted more recently. Similarly, at fixed mass, halos that formed more
recently host more subhalos. Observed "fossil groups" may represent an extreme
tail of this correlation. We find a related correlation between host halo
concentration and subhalo abundance at fixed host mass, Nsat ~ c^-a, where a
changes with redshift and host-to-subhalo mass ratio. Lastly, we use our model
to populate host halos in one of our high-resolution cosmological simulations,
replacing the subhalos resolved in the simulation with subhalos computed
according to our model. We show that the resulting 2pt correlation function of
such a "hybrid" halo ensemble is indistinguishable from that measured directly
in the simulation. This supports one of the key tenets of the standard halo
model -- the assumption that the halo occupation distribution is statistically
independent of host halo environment.


title: Simulations of Strong Gravitational Lensing with Substructure

abstract:
  Galactic sized gravitational lenses are simulated by combining a cosmological
N-body simulation and models for the baryonic component of the galaxy. The lens
caustics, critical curves, image locations and magnification ratios are
calculated by ray-shooting on an adaptive grid. When the source is near a cusp
in a smooth lens' caustic the sum of the magnifications of the three closest
images should be close to zero. It is found that in the observed cases this sum
is generally too large to be consistent with the simulations implying that
there is not enough substructure in the simulations. This suggests that other
factors play an important role. These may include limited numerical resolution,
lensing by structure outside the halo, selection bias and the possibility that
a randomly selected galaxy halo may be more irregular, for example due to
recent mergers, than the isolated halo used in this study. It is also shown
that, with the level of substructure computed from the N-body simulations, the
image magnifications of the Einstein cross type lenses are very weak functions
of source size up to $\sim 1\kpc$. This is also true for the magnification
ratios of widely separated images in the fold and cusp caustic lenses. This
means that selected magnification ratios for different the emission regions of
a lensed quasar should agree with each other, barring microlensing by stars.
The source size dependence of the magnification ratio between the closest pair
of images is more sensitive to substructure.


title:
The decay of interplanetary coronal mass ejections and forbush decrease
  recovery times

abstract:
  We investigate the relation between Forbush cosmic ray decrease recovery time
and coronal mass ejection transit time between the Sun and Earth. We identify
17 Forbush decreases from ground based neutron count rates between 1978 and
2003 that occur during the same phase in the solar cycle and can be associated
with single coronal mass ejections (CMEs) in the SOHO LASCO CME Catalog or
previously published reports, and with specific interplanetary coronal mass
ejections (ICMEs) crossing the vicinity of Earth. We find an anti-correlation
between Forbush recovery times and CME transit time that contradicts the
predictions of simple cosmic ray diffusive barrier models. The anti-correlation
suggests that the decay rate of ICMEs is anti-correlated with their travel
speed. Forbush recovery times range from seven times the transit time for the
fastest disturbance to a fifth the Sun-Earth transit time for the slowest. To
account for the large range of measured recovery times we infer that the
slowest disturbances must decay rapidly with radius whereas the fastest ones
must remain strong. The longest recovery times suggest that the fastest
disturbances in our sample decayed less rapidly with radius than the ambient
solar wind magnetic field strength.


title: Grist: Grid-based Data Mining for Astronomy

abstract:
  The Grist project (http://grist.caltech.edu/) is developing a grid-technology
based system as a research environment for astronomy with massive and complex
datasets. This knowledge extraction system will consist of a library of
distributed grid services controlled by a workflow system, compliant with
standards emerging from the grid computing, web services, and virtual
observatory communities. This new technology is being used to find high
redshift quasars, study peculiar variable objects, search for transients in
real time, and fit SDSS QSO spectra to measure black hole masses. Grist
services are also a component of the ``hyperatlas'' project to serve
high-resolution multi-wavelength imagery over the Internet. In support of these
science and outreach objectives, the Grist framework will provide the enabling
fabric to tie together distributed grid services in the areas of data access,
federation, mining, subsetting, source extraction, image mosaicking,
statistics, and visualization.


title:
The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS
  Observations

abstract:
  We present results of near infrared imaging of the disk-galaxy-merger NGC
6240 using adaptive optics on the Keck II Telescope and reprocessed archival
data from NICMOS on the Hubble Space Telescope. Both the North and South nuclei
of NGC 6240 are clearly elongated, with considerable sub-structure within each
nucleus. In K' band there are at least two point-sources within the North
nucleus; we tentatively identify the south-western point-source within the
North nucleus as the position of one of the two AGNs. Within the South nucleus,
the northern sub-nucleus is more highly reddened. Based upon the nuclear
separation measured at 5 GHz, we suggest that the AGN in the South nucleus is
still enshrouded in dust at K' band, and is located slightly to the north of
the brightest point in K' band. Within the South nucleus there is strong H2 1-0
S(1) line emission from the northern sub-nucleus, contrary to the conclusions
of previous seeing-limited observations. Narrowband H2 emission-line images
show that a streamer or ribbon of excited molecular hydrogen connects the North
and South nuclei. We suggest that this linear feature corresponds to a bridge
of gas connecting the two nuclei, as seen in computer simulations of mergers.
Many point-like regions are seen around the two nuclei. These are most
prominent at 1.1 microns with NICMOS, and in K'-band with Keck adaptive optics.
We suggest that these point-sources represent young star clusters formed in the
course of the merger.


title: Hydrodynamic instability of ionization fronts in HII regions

abstract:
  We investigate hydrodynamic instability of accelerating ionization fronts
using two dimensional hydrodynamic simulations that include detailed energy
deposition and release due to the absorption of UV radiation, recombination of
hydrogen, radiative molecular cooling, and magnetic pressure. We consider
linear perturbation growth and find that the stabilization mechanism associated
with non-accelerated fronts remains a significant factor even when acceleration
is present. Conversely, if recombination in the ionized region is turned
off,Rayleigh-Taylor (RT) instability becomes effective, and the classical RT
growth rate recovered.


title: Influence of the definition of dissipative events on their statistics

abstract:
  A convenient and widely used way to study the turbulent plasma in the solar
corona is to do statistics of properties of events (or structures), associated
with flares, that can be found in observations or in numerical simulations.
Numerous papers have followed such a methodology, using different definitions
of an event, but the reasons behind the choice of a particular definition (and
not another one) is very rarely discussed. We give here a comprehensive set of
possible event definitions starting from a one-dimensional data set such as a
time-series of energy dissipation. Each definition is then applied to a
time-series of energy dissipation issued from simulations of a shell-model of
magnetohydrodynamic turbulence as defined in Giuliani and Carbone (1998), or
from a new model of coupled shell-models designed to represent a magnetic loop
in the solar corona. We obtain distributions of the peak dissipation power,
total energy, duration and waiting-time associated to each definition. These
distributions are then investigated and compared, and the influence of the
definition of an event on statistics is discussed. In particular, power-law
distributions are more likely to appear when using a threshold. The sensitivity
of the distributions to the definition of an event seems also to be weaker for
events found in a highly intermittent time series. Some implications on
statistical results obtained from observations are discussed.


title: IRTS observation of the near-infrared extragalactic background light

abstract:
  We searched for near-infrared extragalactic background light (EBL) in the
data from the Near-InfraRed Spectrometer (NIRS) on the Infrared Telescope in
Space (IRTS). After subtracting the contribution of faint stars and the
zodiacal component based on modeling, a significant isotropic emission is
obtained in the wavelength bands from 1.4 micron to 4.0 micron. The in-band
flux amounts to ~ 35 nW m-2 sr-1 which is too bright to be explained by the
integrated light from faint galaxies.
  Significant fluctuations in sky brightness were also detected which can not
be explained by fluctuations due to faint stars, zodiacal components and normal
galaxies. The excess fluctuation amounts to ~ 1/4 of the excess emission over
the integrated light of galaxies. A two-point correlation analysis shows that
IRTS/NIRS data has an angular scale of fluctuations of a few degrees.
  Recent WMAP results of CMB polarization indicate that the reionization of the
Universe occurred at z ~ 17 or earlier. The observed near infrared background
light could be redshifted UV light from the first generation of massive stars
(Pop.III stars) which caused the reionization of the Universe. The spectral
jump around 1 micron over the optical EBL suggests that massive star formation
terminated at z~9. The observed fluctuations, however, are considerably larger
than the theoretical predictions and require a new scenario for the Pop.III
era.


title:
The influence of chemical composition on the properties of Cepheid stars
  I - Period-Luminosity relation vs iron abundance

abstract:
  We have assessed the influence of the stellar iron content on the Cepheid
Period-Luminosity (PL) relation by relating the V band residuals from the
Freedman et al (2001) PL relation to [Fe/H] for 37 Galactic and Magellanic
Clouds Cepheids. The iron abundances were measured from FEROS and UVES
high-resolution and high-signal to noise optical spectra. Our data indicate
that the stars become fainter as metallicity increases, until a plateau or
turnover point is reached at about solar metallicity. Our data are incompatible
with both no dependence of the PL relation on iron abundance, and with the
linearly decreasing behavior often found in the literature (e.g. Kennicutt et
al 1998, Sakai et al 2004). On the other hand, non-linear theoretical models of
Fiorentino et al (2002) provide a fairly good description of the data.


title: Geometry of Dynamical Systems

abstract:
  We propose a geometrical approach to the investigation of Hamiltonian systems
on (Pseudo) Riemannian manifolds. A new geometrical criterion of instability
and chaos is proposed. This approach is more generic than well known reduction
to the geodesic flow. It is applicable to various astrophysical and
cosmological problems.


title: Protostars and Outflows in the NGC7538 - IRS9 Cloud Core

abstract:
  New high resolution observations of HCO+ J=1-0, H13CN J=1-0, SO 2,2 - 1,1,
and continuum with BIMA at 3.4 mm show that the NGC7538 - IRS9 cloud core is a
site of active ongoing star formation. Our observations reveal at least three
young bipolar molecular outflows, all ~ 10,000 -- 20,000 years old. IRS9 drives
a bipolar, extreme high velocity outflow observed nearly pole on. South of IRS9
we find a cold, protostellar condensation with a size of ~ 14" x 6" with a mass
> 250 Msun. This is the center of one of the outflows and shows deep,
red-shifted self absorption in HCO+, suggesting that there is a protostar
embedded in the core, still in a phase of active accretion. This source is not
detected in the far infrared, suggesting that the luminosity < 10^4 Lsun; yet
the mass of the outflow is ~ 60 Msun. The red-shifted HCO+ self-absorption
profiles observed toward the southern protostar and IRS9 predict accretion
rates of a few times 10^-4 to 10^-3 Msun/yr. Deep VLA continuum observations at
3.6 cm show that IRS9 coincides with a faint thermal VLA source, but no other
young star in the IRS9 region has any detectable free-free emission at a level
of ~ 60 microJy at 3.6 cm. The HCO+ abundance is significantly enhanced in the
hot IRS9 outflow. A direct comparison of mass estimates from HCO+ and CO for
the well-characterized red-shifted IRS9 outflow predicts an HCO+ enhancement of
more than a factor of 30, or [HCO+/H2] >= 6 10^-8.


title: Internal Kinematics of Luminous Compact Blue Galaxies

abstract:
  We describe the dynamical properties which may be inferred from HST/STIS
spectroscopic observations of luminous compact blue galaxies (LCBGs) between
0.1<z<0.7. While the sample is homogeneous in blue rest-frame color, small size
and line-width, and high surface-brightness, their detailed morphology is
eclectic. Here we determine the amplitude of rotation versus random, or
disturbed motions of the ionized gas. This information affirms the accuracy of
dynamical mass and M/L estimates from Keck integrated line-widths, and hence
also the predictions of the photometric fading of these unusual galaxies. The
resolved kinematics indicates this small subset of LCBGs are dynamically hot,
and unlikely to be embedded in disk systems.


title: Jet propagation and the asymmetries of CSS radio sources

abstract:
  As Compact Steep Spectrum radio sources have been shown to be more
asymmetrical than larger sources of similar powers, there is a high probability
that they interact with an asymmetric medium in the central regions of the host
elliptical galaxy. We consider a simple analytical model of the propagation of
radio jets through a reasonable asymmetric environment and show that they can
yield the range of arm-length and luminosity asymmetries that have been
observed. We then generalize this to allow for the effects of orientation, and
quantify the substantial enhancements of the asymmetries that can be produced
in this fashion. We present two-dimensional and three-dimensional simulations
of jets propagating through multi-phase media and note that the results from
the simulations are also broadly consistent with the observations.


title: A study of bright Southern Long Period Variables

abstract:
  In this paper we present radial velocity curves of AGB variables that exhibit
various kinds of anomalies: Semiregular variables (SRVs) with typical mira
periods, SRVs exceeding the mira 2.5 mag amplitude limit, miras with secondary
maxima in their light curves, and a SRV with a long secondary period. The stars
with reliable Hipparcos parallaxes from this and from previous studies are
plotted in a logP-$M_{K}$-diagram. Our objects nicely follow the
logP-$M_{K}$-relations determined for the LMC. This allows the pulsation mode
to be identified. While all miras fall on the fundamental mode sequence, the
SRVs fall on both the first overtone and fundamental mode sequences. The SRVs
on the fundamental mode sequence occur at both high and low luminosities, some
of them being more luminous than larger amplitude miras. This demonstrates
observationally that some parameter other than luminosity affects the stability
of long period variables, probably mass. First overtone pulsators all show
velocity amplitudes around 4 km/s. For the fundamental mode pulsators, the
velocity amplitude shows a correlation with light amplitude. The two miras R
Cen and R Nor, known for their double-peaked light curves, have velocity curves
that are quite different. The R Nor velocity curve shows no evidence of the
double peaks, meaning that the true pulsation period is the time between
alternate minima or maxima. There is slight evidence for a double bump in the R
Cen velocity curve. It is suggested that these stars are relatively massive
(3-5 Msun).


title:
The X-ray source population of the globular cluster M15: Chandra high
  resolution imaging

abstract:
  The globular cluster M15 was observed on three occasions with the High
Resolution Camera on board Chandra in 2001 in order to investigate the X-ray
source population in the cluster centre. After subtraction of the two bright
central sources, four faint sources were identified within 50 arcsec of the
core. One of these sources is probably the planetary nebula, K648, making this
the first positive detection of X-rays from a planetary nebula inside a
globular cluster. Another two are identified with UV variables (one previously
known), which we suggest are cataclysmic variables (CVs). The nature of the
fourth source is more difficult to ascertain, and we discuss whether it is
possibly a quiescent soft X-ray transient (qSXT) or also a CV.


title: Cosmic ray strangelets

abstract:
  Searching for strangelets in cosmic rays may be the best way to test the
possible stability of strange quark matter. I review calculations of the
astrophysical strangelet flux in the GV--TV rigidity range, which will be
investigated from the Alpha Magnetic Spectrometer (AMS-02) on the International
Space Station, and discuss the merits of strangelets as ultra-high energy
cosmic rays at EeV--ZeV energies, beyond the Greisen-Zatsepin-Kuzmin cutoff. I
also address some ``counter-arguments'' sometimes raised against the
possibility of stable strangelets. It will be argued that stability of strange
quark matter remains a viable possibility, which must be tested by experiments.


title:
Chemical evolution in the environment of intermediate mass young stellar
  objects: NGC7129--FIRS2 and LkH$\alpha$234

abstract:
  We have carried out a molecular survey of the Class 0 IM protostar NGC 7129
-- FIRS 2 (hereafter FIRS 2) and the Herbig Be star LkH$\alpha$ 234 with the
aim of studying the chemical evolution of the envelopes of intermediate-mass
(IM) young stellar objects (YSOs). Both objects have similar luminosities (~500
Lsun) and are located in the same molecular cloud which minimizes the chemical
differences due to different stellar masses or initial cloud conditions.
Moreover, since they are located at the same distance, we have the same spatial
resolution in both objects. A total of 17 molecular species (including rarer
isotopes) have been observed in both objects and the structure of their
envelopes and outflows is determined with unprecedent detail.
  Our results show that the protostellar envelopes are dispersed and warmed up
during the evolution to become a pre-main sequence star. In fact, the envelope
mass decreases by a factor >5 from FIRS 2 to LkH$\alpha$234, while the kinetic
temperature increases from ~13K to 28K. On the other hand, there is no
molecular outflow associated with LkH$\alpha$234. The molecular outflow seems
to stop before the star becomes visible. These physical changes strongly affect
the chemistry of their envelopes.
  Based on our results in FIRS2 and LkH$\alpha$ 234, we propose some abundance
ratios that can be used as chemical clocks for the envelopes of IM YSOs. The
SiO/CS, CN/N2H+, HCN/N2H+, DCO+/HCO+ and D2CO/DCO+ ratios are good diagnostics
of the protostellar evolutionary stage.


title:
Fe XXV and Fe XXVI lines from low velocity, photoionised gas in the
  X-ray spectra of AGN

abstract:
  We have calculated the equivalent widths of the absorption lines produced by
Fe XXV and Fe XXVI in a Compton-thin, low-velocity photoionised material
illuminated by the nuclear continuum in AGN. The results, plotted against the
ionisation parameter and the column density of the gas, are a complement to
those presented by Bianchi & Matt 2002 for the emission lines from the same
ionic species. As an extension to the work by Bianchi & Matt 2002, we also
present a qualitative discussion on the different contributions to the He-like
iron emission line complex in the regimes where recombination or resonant
scattering dominates, providing a useful diagnostic tool to measure the column
density of the gas. Future high resolution missions (e.g., Astro-E2) will allow
us to fully take advantage of these plasma diagnostics. In the meantime, we
compare our results with an up-to-date list of Compton-thick and unobscured (at
least at the iron line energy) Seyfert galaxies with emission and/or absorption
lines from H- and He-like iron observed with Chandra and XMM-Newton.


title: Complementary Constraints on Brane Cosmology

abstract:
  The acceleration of the expansion of the universe represents one of the major
challenges to our current understanding of fundamental physics. In principle,
to explain this phenomenon, at least two different routes may be followed:
either adjusting the energy content of the Universe -- by introducing a
negative-pressure dark energy -- or modifying gravity at very large scales --
by introducing new spatial dimensions, an idea also required by unification
theories. In the cosmological context, the role of such extra dimensions as the
source of the dark pressure responsable for the acceleration of our Universe is
translated into the so-called brane world (BW) cosmologies. Here we study
complementary constraints on a particular class of BW scenarios in which the
modification of gravity arises due to a gravitational \emph{leakage} into extra
dimensions. To this end, we use the most recent Chandra measurements of the
X-ray gas mass fraction in galaxy clusters, the WMAP determinations of the
baryon density parameter, measurements of the Hubble parameter from the
\emph{HST}, and the current supernova data. In agreement with other recent
results, it is shown that these models provide a good description for these
complementary data, although a closed scenario is always favored in the joint
analysis. We emphasize that observational tests of BW scenarios constitute a
natural verification of the role of possible extra dimensions in both
fundamental physics and cosmology.


title: Radiation of Accretion Discs in Strong Gravity

abstract:
  In this thesis a computational tool for modelling spectral features of X-ray
sources in a strong gravitational field is developed.
  Six transfer functions, the gravitational and Doppler shift, lensing,
emission angle, relative time delay, change of the polarization angle and
azimuthal emission angle, have been computed for light rays emitted from the
equatorial plane of the Kerr black hole and received by an observer at
infinity. The values of these functions for different angular momenta of the
black hole and inclination angles of the observer in Kerr ingoing coordinates
have been stored in the form of tables in a FITS file. Graphical
representations of the results are shown as an atlas of contour figures of
these functions.
  For the modelling of the spectra of an accretion disc, several general
relativistic codes have been developed. Some of them can be used inside a more
general spectral fitting package XSPEC for routine fitting of the data measured
by X-ray satellites. These are the models for the relativistic emission lines,
Compton reflection and for the general use as a relativistic extension of
existing models (convolution models). Other components of the tool have
extended features for studying non-stationary emission from accretion discs and
polarimetry.
  The newly developed codes have been employed in several applications: data
from XMM-Newton observations of Seyfert galaxy MCG-6-30-15 have been fitted,
emission from an X-ray illuminated spot orbiting near a black hole was
simulated, and polarization from an accretion disc illuminated by a primary
source located above the black hole was computed.


title: Can we test Dark Energy with Running Fundamental Constants ?

abstract:
  We investigate a link between the running of the fine structure constant
$\alpha$ and a time evolving scalar dark energy field. Employing a versatile
parameterization for the equation of state, we exhaustively cover the space of
dark energy models. Under the assumption that the change in $\alpha$ is to
first order given by the evolution of the Quintessence field, we show that
current Oklo, Quasi Stellar Objects and Equivalence Principle observations
restrict the model parameters considerably stronger than observations of the
Cosmic Microwave Background, Large Scale Structure and Supernovae Ia combined.


title:
A method of generating initial conditions for cosmological N body
  simulations

abstract:
  We investigate the possibility of generating initial conditions for
cosmological N-body simulations by simulating a system whose correlations at
thermal equilibrium approximate well those of cosmological density
perturbations. The system is an appropriately modified version of the standard
``one component plasma'' (OCP). We show first how a well-known semi-analytic
method can be used to determine the potential required to produce the desired
correlations, and then verify our results for some cosmological type spectra
with simulations of the full molecular dynamics. The advantage of the method,
compared to the standard one, is that it gives by construction an accurate
representation of both the real and reciprocal space correlation properties of
the theoretical model. Furthermore the distributions are also statistically
homogeneous and isotropic. We discuss briefly the modifications needed to
implement the method to produce configurations appropriate for large N-body
simulations in cosmology, and also the generation of initial velocities in this
context.


title:
The iron $K_\alpha$ lines as a tool for magnetic field estimations in
  non-flat accretion flows

abstract:
  Observations of AGNs and microquasars by ASCA, RXTE, Chandra and XMM-Newton
indicate the existence of broad X-ray emission lines of ionized heavy elements
in their spectra. Such spectral lines were discovered also in X-ray spectra of
neutron stars and X-ray afterglows of GRBs. Recently, Zakharov et al. (MNRAS,
2003, 342, 1325) described a procedure to estimate an upper limit of the
magnetic fields in regions from which X-ray photons are emitted. The authors
simulated typical profiles of the iron $K_\alpha$ line in the presence of
magnetic field and compared them with observational data in the framework of
the widely accepted accretion disk model. Here we further consider typical
Zeeman splitting in the framework of a model of non-flat accretion flows, which
is a generalization of previous consideration into non-equatorial plane motion
of particles emitting X-ray photons.
  Using perspective facilities of space borne instruments (e.g. Constellation-X
mission) a better resolution of the blue peak structure of iron $K_\alpha$ line
will allow to evaluate the magnetic fields with higher accuracy.