title:
About the existence of the exotic molecular ions $(HeH)^{2+}$ and
  $He_2^{3+}$ in a strong magnetic field

abstract:
  The Coulombic systems $(\al p e)$ and $(\al\al e)$, $(\al p p e)$,
  $(\al \al p e)$ and $(Li^{3+} Li^{3+} e)$ placed in a magnetic field $B
\gtrsim 10^{11} {G}$ are studied. It is demonstrated a theoretical existence of
the exotic ion $(He H)^{2+}$ for $B\gtrsim 5\times 10^{12} {G}$ in parallel
configuration (the magnetic field is directed along internuclear axis) as
optimal as well as its excited states $1\pi, 1\delta$. As for the exotic ion
${He}_{2}^{3+}$ it is shown that in spite of strong electrostatic repulsion of
$\al-$particles this ion can also exist for $B \gtrsim 100 {a.u.} (= 2.35\times
10^{11} {G})$ in parallel configuration as optimal in the states $1\si_g$
(ground state), $1\pi_u, 1\delta_g$. Upon appearance both ions are unstable
towards dissociation with $He^+$ in the final state but with very large
lifetime. However, at $B\gtrsim 10000$ a.u. the ion $(He H)^{2+}$ becomes
stable, while at $B\gtrsim 1000$ a.u. the ion ${He}_{2}^{3+}$ becomes stable.
With a magnetic field growth, both exotic ions become more and more tightly
bound and compact, their lowest rotational and vibrational energies grow. At
the edge of applicability of non-relativistic approximation, $B \sim 4.414
\times 10^{13}$ G, there are indications that three more exotic linear ions
$(H-He-H)^{3+}$, $(He-H-He)^{4+}$ and even $Li_2^{5+}$ in parallel
configuration may also occur.


title: A transiting extrasolar giant planet around the star OGLE-TR-10

abstract:
  We report a transiting extrasolar giant planet around the star OGLE-TR-10
(orbital period = 3.1 days), which was uncovered as a candidate by the OGLE
team in their photometric survey towards the Galactic center (Udalski et al,
2002a). We observed OGLE-TR-10 spectroscopically over a period of two years
(2002-2004) using the HIRES instrument with an iodine cell on the Keck I
telescope, and measured small radial velocity variations that are consistent
with the presence of a planetary companion. This confirms the earlier
identification of OGLE-TR-10b by our team and also recently by Bouchy et al
(2004a) as a possible planet. Additionally, in this paper we are able to rule
out a blend scenario as an alternative explanation. From an analysis combining
all available radial velocity measurements with the OGLE light curve we find
that OGLE-TR-10b has a mass of 0.57+/-0.12 MJup and a radius of 1.24+/-0.09
RJup. These parameters bear close resemblance to those of the first known
transiting extrasolar planet, HD 209458b.


title: On the Speed of Gravity and the Jupiter/Quasar Measurement

abstract:
  I present the theory and analysis behind the experiment by Fomalont and
Kopeikin involving Jupiter and quasar J0842+1845 that purported to measure the
speed of gravity. The computation of the v_J/c correction to the gravitational
time delay difference relevant to the experiment is derived, where v_J is the
speed of Jupiter as measured from Earth. Since the v_J/c corrections are too
small to have been measured in the Jupiter/quasar experiment, it is impossible
that the speed of gravity was extracted from the data, and I explain what when
wrong with the data analysis. Finally, mistakes are shown in papers by Fomalont
and Kopeikin intended to rebut my work and the work of others.


title: Bending instabilities at the origin of persistent warps

abstract:
  Based on N-body simulations, we show that realistic galactic disks are
subject to bending instabilities of fire-hose type when the disks are
substantially self-gravitating, that is, if they contain dark matter
distributed in the disk. Depending on the degree of instability, S and
U-shaped, as well as asymmetric warps are generated. In some cases, the warp
may last several galactic rotations, particularly when the instability is
marginal. Since the bending instability is very sensitive to the disk
flattening, the fractions of dark matter distributed in the disk and in the
dark halo are constrained. For a Milky Way like galaxy the extended dark halo
can not exceed 30-40% of the total mass within 35 kpc if the Milky Way warp
results from a bending instability. This mode of warping provides a unified
picture of spiral galaxies, where bars, spiral arms and warps result all from
disk gravitational instabilities, radial or transverse, which are constantly
regenerated by the dissipative gas component.


title: The Polytropic Equation of State of Primordial Gas Clouds

abstract:
  The polytropic equation of state (EOS) of primordial gas clouds with modest
enrichment is computed, motivated by the recent observations of very
Fe-deficient stars, [Fe/H]~10^{-3.5}-10^{-5}, such as HE 0107-5240 and CS
29498-043. These stars are overabundant, relative to Fe, in C and O. We assume
that the observed abundances of species like C, O, Si and Fe are representative
of the gas from which the currently observed metal-deficient stars formed.
Under this assumption, we find that this primordial metal abundance pattern has
profound consequences for the thermal balance and chemical composition of the
gas, and hence for the EOS of the parental cloud. The polytopic EOS is soft for
low, [O/H]<10^{-3}, oxygen abundances, but stiffens to a polytropic index gamma
large than unity for [O/H]>10^{-2} due to the large opacity in the CO and H2O
cooling lines. It is further found that a regulating role is played by the
presence and temperature of the dust, even when the overall carbon abundance is
only [C/H]~10^{-2}. When the dust is warmer than the gas, a region with
gamma~1.2 results around a density of ~10^4 cm^{-3}. When the dust is colder
than the gas, a region with gamma~0.8 is found for a density of ~10^6 cm^{-3}.
Implications for the primordial initial mass function (IMF) as well as the IMF
in starburst galaxies, where the metallicity is super-solar, are explored and
related to processes that influence the temperature of the ambient dust.


title:
An Approach to Explain the Long Cooling Times of Anomalous X-ray Pulsars
  and Soft Gamma Repeaters with the Neutrino Magnetic Moment

abstract:
  The surface temperatures as well as X-ray luminosities of Anomalous X-ray
Pulsars and Soft Gamma Repeaters are several times higher than that of the
ordinary isolated neutron stars at similar ages. We present a simple approach
to explain this observation by the effect of the neutrino magnetic moment on
neutron star cooling. This requires a neutrino magnetic moment about
$(3-5)\times10^{-11}\mu_B$. The simple approach presented in this paper might
be used in determining the exact value of the neutrino magnetic moment and its
contribution to the neutrino-electron scattering when the models to explain
Anomalous X-ray Pulsars and Soft Gamma Repeaters are mature enough.


title:
Correlation between the TeV and X-ray emission in high--energy peaked BL
  Lac objects

abstract:
  We discuss the correlation between the evolution of the TeV emission and
X-ray radiation observed in high-energy peaked BL Lac objects. We describe such
a correlation by a simple power law. In the first part of this work we present
correlations obtained for the activity of Mrk~501 observed in 1997 April and
for the activity of Mrk~421 observed in 2000 February. We also discuss results
of similar correlation obtained for this source by other authors. They report
an almost quadratic correlations observed between the evolution of the TeV and
X-ray emission. In the second part of this paper we present a phenomenological
model which describes the evolution of the synchrotron and inverse Compton
emission of a simple spherical homogeneous source. Neglecting the radiative
cooling of the particles we derive analytical expressions that describe the
evolution. Then we use a numerical code to investigate the impact of radiative
cooling on the evolution. The quadratic correlation observed during the decay
phase of the flare observed in Mrk~421 on 2001 March 19 appears problematic for
this basic modeling. The quadratic correlation can be explained only for
specific choices of the spectral bands used for the calculation. Therefore,
looking for more robust solutions, we investigate the evolution of the emission
generated by a cylindrical source. However this model does not provide robust
solutions for the problem of a quadratic correlation. factor. Finally we
briefly discuss the possible influence of the light travel time effect on our
results.


title: Kinematic Study of the Blazar S5 0716+714

abstract:
  We present the results of a multi-frequency study of the structural evolution
of the VLBI jet in the BL Lac object 0716+714 over the last 10 years. We show
VLBI images obtained at 5 GHz, 8.4 GHz, 15 GHz and 22 GHz. The milliarcsecond
source structure is best described by a one-sided core-dominated jet of ~10 mas
length. Embedded jet components move superluminally with speeds ranging from 5
c to 16 c (assuming z=0.3). Such fast superluminal motion is not typical for BL
Lac objects, however it is still in the range of jet speeds typically observed
in quasars (10 c to 20 c). In 0716+714, younger components, that were ejected
more recently, seem to move systematically slower than the older components.
This and a systematic position angle variation of the inner (1 mas) portion of
the VLBI jet, suggests an at least partly geometric origin of the observed
velocity variations. The observed rapid motion and the derived Lorentz factors
are discussed with regard to the rapid Intra-Day Variability (IDV) and the
gamma-ray observations, from which very high Doppler factors are inferred.


title: Can one hear the shape of the Universe?

abstract:
  It is shown that the recent observations of NASA's explorer mission
"Wilkinson Microwave Anisotropy Probe" (WMAP) hint that our Universe may
possess a non-trivial topology. As an example we discuss the Picard space which
is stretched out into an infinitely long horn but with finite volume.


title:
Spin Flavor Oscillation of Neutrinos in Rotating Gravitational Fields
  and Their Effects on Pulsar Kicks

abstract:
  The origin of high velocities of pulsars is studied by considering the
spin-flip conversion of neutrinos propagating in a gravitational field of a
protoneutron star. For a rotating gravitational source (such as pulsars) with
angular velocity ${\bm \omega}$, one finds that the spin connections (entering
in the Dirac equation written in curved space time) induce an additional
contribution to neutrino energy which is proportional to ${\bm \omega}\cdot
{\bf p}$, with ${\bf p}$ the neutrino momentum. Such a coupling (spin-gravity
coupling) can be responsible of pulsar kicks being the asymmetry of the
neutrino emission generated by the relative orientation of the neutrino
momentum ${\bf p}$ with respect to the angular velocity ${\bm \omega}$. As a
consequence, the mechanism suggests that the motion of pulsars is correlated to
their angular velocity ${\bm \omega}$. In this work we consider neutrinos
propagating orthogonally to the magnetic field. As in the usual approaches,spin
flip conversion is generated via the coupling of the neutrino magnetic momentum
with the magnetic field. For our estimations, we use the large non-standard
neutrino magnetic momentum provided by astrophysical and cosmological
constraints, $\mu_\nu\sim 10^{-11}\mu_B$. The connection with recent
observations and statistical analysis is also discussed.


title: Observation of R-Band Variability of L Dwarfs

abstract:
  We report, for the first time, photometric variability of L dwarfs in $R$
band. Out of three L1 dwarfs (2MASS 1300+19, 2MASS 1439+19, and 2MASS 1658+70)
observed, we have detected R band variability in 2MASS 1300+19 and 2MASS
1439+19. The objects exhibit variability of amplitude ranging from 0.01 mag to
0.02 mag. Object 2MASS 1658+70, turns out to be non-variable in both $R$ and
$I$ band. However, more observations are needed to infer its variability. No
periodic behaviour in the variability is found from the two L1 dwarfs that are
variable. All the three L1 dwarfs have either negligible or no $H_{\alpha}$
activity. In the absence of any direct evidence for the presence of
sufficiently strong magnetic field, the detection of polarization at the
optical favors the presence of dust in the atmosphere of L dwarfs. We suggest
that the observed $R$ band photometric variability is most likely due to
atmospheric dust activity.


title:
Asymmetrical structure of ionization and kinematics in the Seyfert
  galaxy NGC 5033

abstract:
  We present integral field spectroscopy of NGC 5033, a low luminosity Seyfert
galaxy. The observations were made with INTEGRAL, a fiber based system
operating at the WHT. The intensity map of the H$\beta$ emission line
represents a spiral or ring-like pattern of HII regions. On the contrary, the
[OIII] intensity map morphology is markedly anisotropic. The strong
morphological differences imply that the [OIII] emitters represent highly
ionized gas illuminated by the central source. The [OIII] map morphology is
compatible with a biconical structure of ionization induced by strong
extinction in the galaxy disc that also obscures half of the spheroidal stellar
bulge. We identify the spectrum corresponding to the Seyfert 1 nucleus from the
presence of H$\beta$ broad emission lines. This spectrum is located in a region
where strong extinction is expected but exhibits the bluest spectral energy
distribution. The Seyfert 1 nucleus seems to be offcenter with respect to the
stellar rotation center. This result has been also found in other Seyfert
galaxies and interpreted in terms of a past merger. The offcentering could
indicate the presence of nonsymmetric departures in the gravitational potential
which could be fueling the active nucleus. The kinematics of the [OIII]
emitters show important deviations at a kpc scale with respect to the stellar
velocity field and show features related to the asymmetrical morphology of the
high ionization region.


title: Evolution of X-ray spectra of Cygnus X-3 with radio flares

abstract:
  Cygnus X-3, among the X-ray binaries, is one of the brightest in the radio
band, repeatedly exhibiting huge radio flares. The X-ray spectra shows two
definite states, low (correspondingly hard) and high (correspondingly soft).
During the hard state the X-ray spectra shows a pivoting behaviour correlated
to the radio emission. In the high state the X-ray spectra shows a gamut of
behaviour which controls the radio flaring activity of the source. The complete
evolution of the X-ray spectra along with the radio flaring activity is
reported here, for the first time for this source.


title: Rapid GRB Follow-up with the 2-m Robotic Liverpool Telescope

abstract:
  We present the capabilities of the 2-m robotic Liverpool Telescope (LT),
owned and operated by Liverpool John Moores University and situated at ORM, La
Palma. Robotic control and scheduling of the LT make it especially powerful for
observations in time domain astrophysics including: (i) rapid response to
Targets of Opportunity: Gamma Ray Bursts, novae, supernovae, comets; (ii)
monitoring of variable objects on timescales from seconds to years, and (iii)
observations simultaneous or coordinated with other facilities, both
ground-based and from space. Following a GRB alert from the Gamma Ray
Observatories HETE-2, INTEGRAL and Swift we implement a special over-ride mode
which enables observations to commence in about a minute after the alert,
including optical and near infrared imaging and spectroscopy. In particular,
the combination of aperture, site, instrumentation and rapid response (aided by
its rapid slew and fully-opening enclosure) makes the LT excellently suited to
help solving the mystery of the origin of optically dark GRBs, for the
investigation of short bursts (which currently do not have any confirmed
optical counterparts) and for early optical spectroscopy of the GRB phenomenon
in general. We briefly describe the LT's key position in the RoboNet-1.0
network of robotic telescopes.


title: Variable-Mass Dark Matter and the Age of the Universe

abstract:
  Models with variable-mass particles, called VAMPs, have been proposed as a
solution to the cosmic coincidence problem that plagues dark energy models. In
this contribution we make a short description of this class of models and
explore some of its observational consequences. In particular, we show that
fine tuning is still required in this scenario and that the age of the Universe
is considerably larger than in the standard Lambda-CDM model.


title: Was the Narrow Line Seyfert 1 RGB J0044+193 ever radio loud?

abstract:
  We show new radio data and a re-analysis of old data for the Narrow Line
Seyfert 1 (NLSy1) galaxy RGB J0044+193. This galaxy has previously been
suggested to be both radio loud, and highly variable in the radio. As most NLSy
1 galaxies are radio quiet, this was interpreted as possible evidence that this
AGN's jet was beamed toward the observer. This object was probably never either
radio loud and nor variable -- the one exception to this rule is a marginal
detection of the object in the 1987 Green Bank survey, which we argue may have
been spurious.


title: Via Aristotle, Leibniz & Mach to a relativistic relational gravity

abstract:
  In previous work we have shown how a worldview that has its origins in the
ideas of Aristotle, Leibniz and Mach leads to a quasi-classical (that is,
one-clock) metric theory of gravitation (astro-ph/0107397) which, for example,
when applied to model low surface brightness spirals (astro-ph/0306228),
produces results that have, hitherto, only been matched by Milgrom's MOND
algorithm. In this paper we show how the natural generalization of this
worldview into a properly relativistic two-clock theory, applied to model a
spherically symmetric gravitational source, produces results that cannot be
distinguished from the canonical picture for all the standard local tests and
which, when interpreted as a radiation model, produces no dipole radiation.
Furthermore, although black-holes within this picture have an event horizon at
the usual Schwarzschild radius, they do not have an essential singularity at
the origin - the solutions are perfectly regular there.


title:
Mergers and binary systems of SMBH in the contexts of nuclear activity
  and galaxy evolution

abstract:
  The dynamic evolution of binary systems of supermassive black holes (SMBH)
may be a key factor affecting a large fraction of the observed properties of
active galactic nuclei (AGN) and galaxy evolution. Different classes of AGN can
be related in general to four evolutionary stages in a binary SMBH: 1) early
merger stage; 2) wide pair stage; 3) close pair stage; and 4) pre-coalescence
stage. This scheme can explain a variety of properties of AGN: radio and
optical luminosity differences between different classes of AGN, long-term and
short-term variability, quasi-periodic nuclear flares, recurrent formation of
relativistic outflows in AGN and their apparent morphology and kinematics.


title: Dust Attenuation caused by Isothermal Turbulent Media

abstract:
  Our ability to correct the observational photometry of galaxies depends upon
our knowledge of the attenuation of light produced by the dust contained in the
interstellar medium.
  We will present a model based on the statistical properties of the local
density in isothermal turbulence which might be appropriate to calculate the
radiative transport through the diffuse interstellar medium. The model will be
applied to study the attenuation caused by a distant foreground screen and a
non scattering slab where the sources are mixed within the turbulent medium. It
will be shown how the turbulent structure affects the attenuation curve and how
the attenuation curve varies with the thickness of a foreground screen.


title: Quasars formation around clusters of primordial black holes

abstract:
  We propose the model of first quasars formation around the cluster of
rimordial black holes (PBHs). It is supposed, that mass fraction of the
universe ~10^-3 is composed of the compact clusters of PBHs, produced during
the phase transitions in the early universe. The clusters of PBHs become the
centers of dark matter condensation. As a result, the galaxies with massive
central black holes are formed. In the process of galaxies formation the
central black holes are growing due to accretion. This accretion is acompaned
by the early quasar activity.


title:
Do the Unidentified EGRET Sources Trace Annihilating Dark Matter in the
  Local Group?

abstract:
  In a cold dark matter (CDM) framework of structure formation, the dark matter
haloes around galaxies assemble through successive mergers with smaller haloes.
This merging process is not completely efficient, and hundreds of surviving
halo cores, or {\it subhaloes}, are expected to remain in orbit within the halo
of a galaxy like the Milky Way. While the dozen visible satellites of the Milky
Way may trace some of these subhaloes, the majority are currently undetected. A
large number of high-velocity clouds (HVCs) of neutral hydrogen {\it are}
observed around the Milky Way, and it is plausible that some of the HVCs may
trace subhaloes undetected in the optical. Confirming the existence of
concentrations of dark matter associated with even a few of the HVCs would
represent a dramatic step forward in our attempts to understand the nature of
dark matter. Supersymmetric (SUSY) extensions of the Standard Model of particle
physics currently suggest neutralinos as a natural well-motivated candidate for
the non-baryonic dark matter of the universe. If this is indeed the case, then
it may be possible to detect dark matter indirectly as it annihilates into
neutrinos, photons or positrons. In particular, the centres of subhaloes might
show up as point sources in gamma-ray observations. In this work we consider
the possibility that some of the unidentified EGRET $\gamma$-ray sources trace
annihilating neutralino dark matter in the dark substructure of the Local
Group. We compare the observed positions and fluxes of both the unidentified
EGRET sources and the HVCs with the positions and fluxes predicted by a model
of halo substructure, to determine to what extent any of these three
populations could be associated.


title: On the high coherence of kilo-Hz Quasi-Periodic Oscillations

abstract:
  We have carried out a systematic study of the properties of the kilo-Hertz
quasi-periodic oscillations (QPO) observed in the X-ray emission of the neutron
star low-mass X-ray binary 4U1608-52, using archival data obtained with the
Rossi X-ray Timing Explorer. We have investigated the quality factor, Q, of the
oscillations (defined as the ratio of the frequency of the QPO peak to its full
width at half maximum). In order to minimise the effect of long-term frequency
drifts, power spectra were computed over the shortest times permitted by the
data statistics. We show that the high Q of ~200 reported by Berger et al.
(1996) for the lower frequency kilo-Hz QPO in one of their observations is by
no means exceptional, as we observe a mean Q value in excess of 150 in 14 out
of the 21 observations analysed and Q can remain above 200 for thousands of
seconds. The frequency of the QPO varies over the wide range 560--890 Hz and we
find a systematic trend for the coherence time of the QPO, estimated as tau=Q
/(pi nu), to increase with the frequency, up to a maximum level at ~ 800 Hz,
beyond which it appears to decrease, at frequencies where the QPO weakens.
There is a more complex relationship between tau and the QPO root mean squared
amplitude (RMS), in which positive and negative correlations can be found. A
higher-frequency QPO, revealed by correcting for the frequency drift of the
560-890 Hz one, has a much lower Q (~10) which does not follow the same
pattern. We discuss these results in the framework of competing QPO models and
show that those involving clumps orbiting within or above the accretion disk
are ruled out.


title: Rapid variability of the kHz-QPO frequency in 4U1608-52

abstract:
  We investigate the variability of the QPO frequency in 4U1608-52 on very
short time scales of a few seconds. We detect changes in frequency as fast as
0.5 Hz/s, which is more than ten times the fastest change reported for this
object. Using a structure function analysis, we are able to detect variability
on time scales as short as ~4 seconds. We do not detect any time asymmetry in
the QPO-frequency history. These results have important consequences on the
measurement of the QPO coherence.


title:
The Binary Frequency Among Carbon-Enhanced, s-Process Rich, Metal-Poor
  Stars

abstract:
  We discuss radial velocities for a sample of carbon-enhanced, s-process rich,
very metal-poor stars (CEMP-s hereafter), analyzed with high-resolution
spectroscopy obtained over multiple epochs. We find that ~68% of the stars in
the sample show evidence of radial velocity variations. The expected detection
fraction for these stars, adopting the measured binary fraction in the field
(~60%), and assuming that they share the same period and eccentricity
distribution, is ~22%. Even if one assumes that the true binary fraction of
these stars is 100%, the expected detection percentage is ~36%. These values
indicate that the binary fraction among CEMP-s stars is higher than the field
binary fraction, suggesting that all of these objects are in double (or
multiple) systems. The fact that the observed frequency of velocity variation
exceeds the expected detection fraction in the case of an assumed binary
fraction of 100% is likely due to a more restricted distribution of orbital
periods for these objects, as compared to normal field binaries. Our results
indicate that CEMP-s stars are the metal-poor analogues of classical CH-stars.


title: Observational evidence for a different IMF in the early Galaxy

abstract:
  The unexpected high incidence of carbon-enhanced, s-process enriched
unevolved stars amongst extremely metal-poor stars in the halo provides a
significant constraint on the Initial Mass Function (IMF) in the early Galaxy.
We argue that these objects are evidence for the past existence of a large
population of intermediate-mass stars, and conclude that the IMF in the early
Galaxy was different from the present, and shifted toward higher masses.


title: Properties and Spectral Behaviour of Cluster Radio Halos

abstract:
  Several arguments have been presented in the literature to support the
connection between radio halos and cluster mergers. The spectral index
distributions of the halos in A665 and A2163 provide a new strong confirmation
of this connection, i.e. of the fact that the cluster merger plays an important
role in the energy supply to the radio halos. Features of the spectral index
(flattening and patches) are indication of a complex shape of the radiating
electron spectrum, and are therefore in support of electron reacceleration
models. Regions of flatter spectrum are found to be related to the recent
merger. In the undisturbed cluster regions, instead, the spectrum steepens with
the distance from the cluster center.The plot of the integrated spectral index
of a sample of halos versus the cluster temperature indicates that clusters at
higher temperature tend to host halos with flatter spectra. This correlation
provides further evidence of the connection between radio emission and cluster
mergers.


title: On the thermal behaviour of small iron grains

abstract:
  The optical properties of small spherical iron grains are derived using a
Kramers-Kronig-consistent model of the dielectric function including its
dependence on temperature and size. Especially discussed is the effect of the
size dependence, which results from the limitation of the free path of the free
electrons in the metal by the size of the grain, on the absorption behaviour of
small iron spheres and spheroids. The estimated absorption properties are
applied to study the temperature behaviour of spherical and spheroidal grains
which are heated by the interstellar radiation field.


title:
Cosmological Cosmic Rays and the observed Li6 plateau in metal poor halo
  stars

abstract:
  Very recent observations of the Li6 isotope in halo stars reveal a Li6
plateau about 1000 times above the predicted BBN abundance. We calculate the
evolution of Li6 versus redshift generated from an initial burst of
cosmological cosmic rays (CCRs) up to the formation of the Galaxy. We show that
the pregalactic production of the Li6 isotope can account for the Li6 plateau
observed in metal poor halo stars without additional over-production of Li7.
The derived relation between the amplitude of the CCR energy spectra and the
redshift of the initial CCR production puts constraints on the physics and
history of the objects, such as pop III stars, responsible for these early
cosmic rays. Consequently, we consider the evolution of Li6 in the Galaxy.
Since Li6 is also produced in Galactic cosmic ray nucleosynthesis, we argue
that halo stars with metallicities between [Fe/H] = -2 and -1, must be somewhat
depleted in Li6.


title:
HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular
  Gas and Implications for Cloud Evolution and Star Formation

abstract:
  We present the results of a comparative study of HI narrow self-absorption
(HINSA), OH, 13CO, and C18O in five dark clouds. The HINSA follows the
distribution of the emission of the carbon monoxide isotopologues, and has a
characteristic size close to that of 13CO. This confirms that the HINSA is
produced by cold HI which is well mixed with molecular gas in well-shielded
regions. The ratio of the atomic hydrogen density to total proton density for
these sources is 5 to 27 x 10^{-4}. Using cloud temperatures and the density of
HI, we set an upper limit to the cosmic ray ionization rate of 10^{-16} s^{-1}.
Comparison of observed and modeled fractional HI abundances indicates ages for
these clouds to be 10^{6.5} to 10^{7} yr. The low values of the HI density we
have determined make it certain that the time scale for evolution from an
atomic to an almost entirely molecular phase, must be a minimum of several
million years. This clearly sets a lower limit to the overall time scale for
star formation and the lifetime of molecular clouds.


title: Kinematics of RHB stars to trace the structure of the galaxy

abstract:
  Red horizontal-branch (RHB) stars have been selected from the HIPPARCOS
catalogue to investigate their kinematics and spatial distribution. HIPPARCOS
parallaxes, literature radial velocities and HIPPARCOS proper motions, together
with models for the gravitational potential of the Milky Way allow a
calculation of the actual velocity vectors and the orbits of the RHB stars. The
velocity characteristics are used to define a halo population sample (HPS) in
the collection of RHBs. The orbits lead statistically to an overall z-distance
probability distribution, showing that the RHBs exhibit two populations, a disk
one having a scale height of h_disk ~0.6 kpc and a halo one of ~4 kpc. We have
investigated the influence on our results of parallax accuracy and of a
demarcation line in the HRD between the RHB and the red-giant (RG) star region.
Neither of them show marked effects. We have performed the orbit analysis using
the potential model of Allen & Santillan as well as of Dehnen & Binney. The
results differ only slightly for the disk population, showing that these
potential models are not a critical part of such orbit investigations. RHB
scale height values are smaller than those found earlier for sdB stars, most
likely because the samples of stars used had different spatial distributions a
priori. The data do not allow us to specify a trend in the kinematic behaviour
of star types along the horizontal branch.


title: Concluding Remarks: Gaia and Astrophysics in 2015-2020

abstract: Conference Summary


title: AWM 4 - an isothermal cluster observed with XMM-Newton

abstract:
  We present analysis of an XMM observation of the poor cluster AWM 4. The
cluster is relaxed and its X-ray halo is regular with no apparent substructure.
Azimuthally averaged radial spectral profiles suggest that the cluster is
isothermal to a radius of at least 160 kpc, with no evidence of a central
cooling region. Spectral mapping shows some significant temperature and
abundance substructure, but no evidence of strong cooling in the cluster core.
Abundance increases in the core, but not to the extent expected, and we find
some indication of gas mixing. Modeling the three dimensional properties of the
system, we show that ongoing heating by an AGN in the dominant elliptical, NGC
6051, is likely to be responsible for the lack of cooling. We also compare AWM
4 to MKW 4, a cluster of similar mass observed recently with XMM. While the two
systems have similar gravitational mass profiles, MKW 4 has a cool core and
somewhat steeper gas density profile, which leads to a lower core entropy. AWM
4 has a considerably larger gas fraction at 0.1 R200, and we show that these
differences result from the difference in mass between the two dominant
galaxies and the activity cycles of their AGN. We estimate the energy required
to raise the temperature profile of MKW 4 to match that of AWM 4 to be 9x10^58
erg, or 3x10^43 erg/s for 100 Myr, comparable to the likely power output of the
AGN in AWM 4.


title: A Serendipitous XMM-Newton Observation of the Intermediate Polar WX Pyx

abstract:
  We briefly describe a serendipitous observation of the little-studied
intermediate polar WX Pyx using XMM-Newton. The X-ray spin period is 1557.3
sec, confirming the optical period published in 1996. An orbital period of
approximately 5.54 hr is inferred from the separation of the spin-orbit
sidelobe components. The soft and hard band spin-folded light curves are nearly
sinusoidal in shape. The best-fit spectrum is consistent with a bremsstrahlung
temperature of about 18 keV. An upper limit of approximately 300 eV is assigned
to the presence of Fe line emission. WX Pyx lies near TX and TV Col in the
P_spin-P_orb plane.


title:
Deep VLT V-band Imaging of the Field of a z=10 Candidate Galaxy: Below
  the Lyman Limit?

abstract:
  We present a deep 16.8 ks V-band image of the field of a candidate z=10
galaxy magnified by the foreground (z=0.25) cluster A1835. The image was
obtained with FORS1 on VLT-Kueyen to test whether the V-band lies below the
Lyman limit for this very high redshift candidate. A detection would
unambiguously rule out that the source is at z=10. The 3sigma detection limit
of the image in the area of the z=10 candidate is V_AB=28.0 mag in a 2 arcsec
diameter aperture (about 3 times the seeing FWHM of 0.7 arcsec). No source at
the position of the candidate galaxy is detected down to this limit. Formally,
this is consistent with the V-band probing below the Lyman limit in the
rest-frame of a z=10 source. However, given the recent non-detection of the
object in a deep H-band exposure with NIRI on Gemini North down to H_AB=26.0
mag (3sigma in a 1.4 arcsec aperture) and concerns about the detection of the
reported associated emission line, it may be possible that this source is
spurious. We discuss several astrophysical possibilities to explain the
puzzling nature of this source and find none of them compelling.


title:
The Nuclear Orbital Distribution in Galaxies as Fossil Record of Black
  Hole Formation from Integral-Field Spectroscopy

abstract:
  In the past decade, most effort in the study of supermassive black holes
(BHs) has been devoted to measuring their masses. This lead to the finding of
the tight M_BH-sigma relation, which indicates the existence of strong links
between the formation of the BH and of their host spheroids. Many scenarios
have been proposed to explain this relation, and all agree on the key role of
BHs' growth and feedback in shaping their host galaxies. However the currently
available observational constraints, essentially BH masses and galaxy
photometry, are not sufficient to conclusively select among the alternatives. A
crucial piece of information of the black hole formation is recorded in the
orbital distribution of the stars, which can only be extracted from
high-resolution integral-field (IF) stellar kinematics. The introduction of IF
spectrographs with adaptive optics on large telescopes opens a new era in the
study of BHs by finally allowing this key element to be uncovered. This
information will be complementary to what will be provided by the LISA
gravitational wave satellite, which can directly detect coalescing BHs. Here an
example is presented for the recovery of the orbital distribution in the center
of the giant elliptical galaxy M87, which has a well resolved BH sphere of
influence, using SAURON IF kinematics.


title: Photometric observations of SARS clusters: Galaxy Luminosity Profiles

abstract:
  We have analyzed CCD images of 14 Abell clusters in the R filter of the SARS
survey (Way et al 2004), with cz<40000kms^{-1}. We have obtained the luminosity
profiles for 507 galaxies of which 232 (46%) have known redshifts. In order to
fit the luminosity profiles we used the de Vaucouleurs law for bulge systems,
an exponential profile for disk systems and we have also fitted the Sersic's
law (r^n) to all galaxy profiles. We have found that 162 (32%) galaxies in the
sample have pure r^{1/4} profiles, 168 (33%) have pure exponential profiles,
while 93 (18%) galaxies have luminosity profiles that are well fitted by a
combination of both bulge and disk profiles. On the other hand, we could not
fit the classical bulge + disk profile to the remaining 84 (17%) galaxies of
the sample. For such cases we have only used the Sersic law. We have also
analyzed how seeing and sky cleaning affect the structural and photometric
parameters obtained through profile fitting. In addition, we have studied
several relations between these parameters. We have found that bulges and disks
show consistency with a unique relation in the \mu_e - log(r_e) plane. We also
found that bulges and disks obey a magnitude-size relation in the sense that
large bulges and disks (large r_e values) have high luminosities. On the other
hand, Sersic law fitting parameters n, $rs$ and \mu_s show a strong correlation
in agreement with other authors suggesting the idea that not only ellipticals
but all galaxies are likely to be understood as a one parameter family.


title:
Group, field and isolated early-type galaxies II. Global trends from
  nuclear data

abstract:
  We have derived ages, metallicities and enhanced-element ratios [alpha/Fe]
for a sample of 83 early-type galaxies essentially in groups, the field or
isolated objects. The stellar population properties derived for each galaxy
corresponds to the nuclear r_e/8 aperture extraction. The median age found for
Es is 5.8 +- 0.6 Gyr and the average metallicity is +0.37 +- 0.03 dex. For S0s,
the median age is 3.0 +- 0.6 Gyr and [Z/H] = 0.53 +- 0.04 dex. We compare the
distribution of our galaxies in the Hbeta-[MgFe] diagram with Fornax galaxies.
Our elliptical galaxies are 3-4 Gyr younger than Es in the Fornax cluster. We
find that the galaxies lie in a plane defined by [Z/H] = 0.99 log sigma_0 -
0.46 log Age - 1.60. More massive (larger sigma_0) and older galaxies present,
on average, large [alpha/Fe] values, and therefore, must have undergone shorter
star-formation timescales. Comparing group against field/isolated galaxies, it
is not clear that environment plays an important role in determining their
stellar population history. In particular, our isolated galaxies show ages
differing in more than 8 Gyr. Finally we explore our large spectral coverage to
derive log(O/H) metallicity from the N2 indicator and compare it with
model-dependent [Z/H]. We find that the O/H abundances are similar for all
galaxies, and we can interpret it as if most chemical evolution has already
finished in them.


title:
A new Search for Carbon Monoxide Absorption in the Transmission Spectrum
  of the Extrasolar Planet HD 209458b

abstract:
  We have revisited the search for carbon monoxide absorption features in
transmission during the transit of the extrasolar planet HD 209458b. We
acquired 1077 high resolution spectra at 2 microns using NIRSPEC on Keck II
during three transits. Our sensitivity is sufficient to test the degree of CO
absorption in the first overtone bands during transit, based on plausible
models of the planetary atmosphere. We compare to theoretical tangent geometry
absorption spectra, computed by adding height-invariant ad hoc temperature
pertubations to the model atmosphere of Sudarsky et al., and by treating cloud
height as an adjustable parameter. We do not detect CO absorption. Our analysis
indicates a weakening similar to the case of sodium, suggesting that a general
masking mechanism is at work in the planetary atmosphere. If this masking is
provided by high clouds, our analysis defines the maximum cloud top pressure
(i.e., minimum height) as a function of the model atmospheric temperature. For
the relatively hot model used by Charbonneau et al. to interpret their sodium
detection, our CO limit requires cloud tops at or above 3.3 mbar, and these
clouds must be opaque at a wavelength of 2 microns. High clouds comprised of
submicron-sized particles are already present in some models, but may not
provide sufficient opacity to account for our CO result. Cooler model
atmospheres, having smaller atmospheric scale heights and lower CO mixing
ratios, may alleviate this problem to some extent. However, even models 500K
cooler that the Sudarsky et al. model require clouds above the 100 mbar level
to be consistent with our observations. Our null result therefore requires that
clouds exist at an observable level in the atmosphere of HD 209458b, unless
this planet is dramatically colder than current belief.


title: ALMA: Galaxies and AGN

abstract:
  With the ability to see into optically obscured regions with more than an
order of magnitude better sensitivity and spatial resolution relative to
current (sub)mm telescopes, ALMA will provide a unique look into the physics of
galaxy formation and active galactic nuclei. In this paper I summarize the ALMA
potential for studying star forming galaxies and active galactic nuclei from
the nearby universe to the epoch of formation of the first luminous objects.


title: Observations and modeling of the inner disk region of T Tauri stars

abstract:
  We present observations of four T Tauri stars using long baseline infrared
interferometry from the Palomar Testbed Interferometer. The target sources, T
Tau N, SU Aur, RY Tau and DR Tau, are all known to be surrounded by dusty
circumstellar disks. The observations directly trace the inner regions (< 1 AU)
of the disk and can be used to constrain the physical properties of this
material. For three of the sources observed, the infrared emission is clearly
resolved. We first use geometric models to characterize the emission region
size, which ranges from 0.04 to 0.3 AU in radius. We then use Monte Carlo
radiation transfer models of accretion disks to jointly model the spectral
energy distribution and the interferometric observations with disk models
including accretion and scattering. With these models, we are able to reproduce
the data set with extended emission arising from structures larger than 10
milliarcseconds contributing less than 6% of the K band emission, consistent
with there being little or no envelope remaining for these Class II sources (d
log(lambda*F_lambda)/d log(lambda) ~ -2 to 0 in the infrared). The radiation
transfer models have inner radii for the dust similar to the geometric models;
however, for RY Tau emission from gas within the inner dust radius contributes
significantly to the model flux and visibility at infrared wavelengths. The
main conclusion of our modeling is that emission from inner gas disks (between
the magnetic truncation radius and the dust destruction radius) can be a
significant component in the inner disk flux for sources with large inner dust
radii.


title: Correlated Primordial Perturbations in Light of CMB and LSS Data

abstract:
  We use cosmic microwave background (CMB) and large-scale structure data to
constrain cosmological models where the primordial perturbations have both an
adiabatic and a cold dark matter (CDM) isocurvature component. We allow for a
possible correlation between the adiabatic and isocurvature modes, and for
different spectral indices for the power in each mode and for their
correlation. We do a likelihood analysis with 11 independent parameters. We
discuss the effect of choosing the pivot scale for the definition of amplitude
parameters. The upper limit for the isocurvature fraction is 18% around a pivot
scale k = 0.01 Mpc^{-1}. For smaller pivot wavenumbers the limit stays about
the same. For larger pivot wavenumbers, very large values of the isocurvature
spectral index are favored, which makes the analysis problematic, but larger
isocurvature fractions seem to be allowed. For large isocurvature spectral
indices n_iso > 2 a positive correlation between the adiabatic and isocurvature
mode is favored, and for n_iso < 2 a negative correlation is favored. The upper
limit to the nonadiabatic contribution to the CMB temperature variance is 7.5%.
Of the standard cosmological parameters, determination of the CDM density
$\omega_c$ and the sound horizon angle $\theta$ (or the Hubble constant $H_0$)
are affected most by a possible presence of a correlated isocurvature
contribution. The baryon density $\omega_b$ nearly retains its ``adiabatic
value''.


title: New solar opacities, abundances, helioseismology, and neutrino fluxes

abstract:
  We construct solar models with the newly calculated radiative opacities from
the Opacity Project (OP) and recently determined (lower) heavy element
abundances. We compare results from the new models with predictions of a series
of models that use OPAL radiative opacities, older determinations of the
surface heavy element abundances, and refinements of nuclear reaction rates.
For all the variations we consider, solar models that are constructed with the
newer and lower heavy element abundances advocated by Asplund et al. (2005)
disagree by much more than the estimated measuring errors with
helioseismological determinations of the depth of the solar convective zone,
the surface helium composition, the internal sound speeds, and the density
profile. Using the new OP radiative opacities, the ratio of the 8B neutrino
flux calculated with the older and larger heavy element abundances (or with the
newer and lower heavy element abundances) to the total neutrino flux measured
by the Sudbury Neutrino Observatory is 1.09 (0.87) with a 9% experimental
uncertainty and a 16% theoretical uncertainty, 1 sigma errors.


title: Triaxial haloes, intrinsic alignments and the dark matter power spectrum

abstract:
  (Abridged) We develop the halo model of large-scale structure to include
triaxial dark matter haloes and their intrinsic alignments. As a direct
application we derive general expressions for the power spectrum. This we
calculate for two different triaxial density profiles. The first is a toy-model
that allows us to isolate the dependence of clustering on halo shape alone and
the second is the more realistic model of Jing & Suto (2002). In both cases, we
find that the effects of triaxiality are manifest as a suppression of power at
the level of ~5% on scales k~1-10 h/Mpc. When considered by mass, we find that
for the first model the power is suppressed and that this is more significant
for high mass haloes. For the Jing & Suto model, we find a similar suppression
on large scales, but followed by a sharp amplification on small scales at the
level of ~10-15%, for the highest mass haloes.
  One of the important features of our formalism is that it allows for the
self-consistent inclusion of the intrinsic alignments of haloes. The alignments
are specified through the correlation function of halo seeds. We develop a
useful toy model for this and make estimates of the alignment contribution to
the power spectrum. Further, through consideration of the case where all haloes
are perfectly aligned, we calculate the maximum contribution to the clustering
and find the hard limit of <10%.


title: The phase-space density distribution of dark matter halos

abstract:
  High resolution N-body simulations have all but converged on a common
empirical form for the shape of the density profiles of halos, but the full
understanding of the underlying physics of halo formation has eluded them so
far. We investigate the formation and structure of dark matter halos using
analytical and semi-analytical techniques. Our halos are formed via an extended
secondary infall model (ESIM); they contain secondary perturbations and hence
random tangential and radial motions which affect the halo's evolution at it
undergoes shell-crossing and virialization. Even though the density profiles of
NFW and ESIM halos are different their phase-space density distributions are
the same: \rho/\sigma^3 ~ r^{-\alpha}, with \alpha=1.875 over ~3 decades in
radius. We use two approaches to try to explain this ``universal'' slope: (1)
The Jeans equation analysis yields many insights, however, does not answer why
\alpha=1.875. (2) The secondary infall model of the 1960's and 1970's,
augmented by ``thermal motions'' of particles does predict that halos should
have \alpha=1.875. However, this relies on assumptions of spherical symmetry
and slow accretion. While for ESIM halos these assumptions are justified, they
most certainly break down for simulated halos which forms hierarchically. We
speculate that our argument may apply to an ``on-average'' formation scenario
of halos within merger-driven numerical simulations, and thereby explain why
\alpha=1.875 for NFW halos. Thus, \rho/\sigma^3 ~ r^{-1.875} may be a generic
feature of violent relaxation.


title: Contamination in the MACHO dataset and the puzzle of LMC Microlensing

abstract:
  In a recent series of three papers, Belokurov, Evans, and Le Du, and Evans
and Belokurov, reanalysed the MACHO collaboration data and gave alternative
sets of microlensing events and an alternative optical depth to microlensing
toward the Large Magellanic Cloud (LMC). Even though they examined less than
0.2% of the data they claimed that by using a neural net program they had
reliably selected a better (and smaller) set of microlensing candidates.
Estimating the optical depth from this smaller set, they claim that the MACHO
collaboration overestimated the optical depth by a significant factor and that
the MACHO microlensing experiment is consistent with lensing by known stars in
the Milky Way and LMC. As we show below, the analysis by these authors contains
several errors which render their conclusions meaningless. Their efficiency
analysis is clearly in error, and since they did not search through the entire
MACHO dataset, they do not know how many microlensing events their neural net
would find in the data or what optical depth their method would give.
Examination of their selected events suggests that their method misses low S/N
events and thus would have lower efficiency than the MACHO selection criteria.
In addition, their method is likely to give many more false positives
(non-lensing events identified as lensing). Both effects would increase their
estimated optical depth. Finally, we note that the EROS discovery that LMC
event-23 is a variable star reduces the MACHO collaboration estimates of
optical depth and Macho halo fraction by around 8%, and does open the question
of additional contamination.


title: Models of Giant Planet formation with migration and disc evolution

abstract:
  We present a new model of giant planet formation that extends the
core-accretion model of Pollack etal (1996) to include migration, disc
evolution and gap formation. We show that taking into account these effects can
lead to a much more rapid formation of giant planets, making it compatible with
the typical disc lifetimes inferred from observations of young circumstellar
discs. This speed up is due to the fact that migration prevents the severe
depletion of the feeding zone as observed in in situ calculations. Hence, the
growing planet is never isolated and it can reach cross-over mass on a much
shorter timescale. To illustrate the range of planets that can form in our
model, we describe a set of simulations in which we have varied some of the
initial parameters and compare the final masses and semi-major axes with those
inferred from observed extra-solar planets.


title: Strong lensing constraints on the properties of cluster galaxies

abstract:
  A recently discovered quadruply-imaged QSO, SDSS J1004+4112 (Inada et al.
2003; Oguri et al. 2004) in the core of a $z=0.68$ galaxy cluster has an
unprecedented image separation of ~13''. This lens gives us a unique
opportunity to study the detailed mass distribution in the central regions of
this cluster. We present free-form reconstructions of the lens using recently
developed methods. The projected mass within 100 kpc is well-constrained as
5+/-1 x 10^{13} M_solar, consistent with previous simpler models. Unlike
previous work, however, we are able to detect structures in the lens associated
with cluster galaxies. We estimate the mass associated with these galaxies, and
show that they contribute not more than about 10% of the total cluster mass
within 100 kpc. Typical galaxy masses, combined with typical luminosities yield
a rough estimate of their mass-to-light ratio, which is ~<10, implying that
these galaxies consist mostly of stars, and possess little dark matter.


title:
The State of the Circumstellar Medium Surrounding Gamma-Ray Burst
  Sources and its Effect on the Afterglow Appearance

abstract:
  We present a numerical investigation of the contribution of the presupernova
ejecta of Wolf-Rayet stars to the environment surrounding gamma-ray bursts
(GRBs), and describe how this external matter can affect the observable
afterglow characteristics. An implicit hydrodynamic calculation for massive
stellar evolution is used here to provide the inner boundary conditions for an
explicit hydrodynamical code to model the circumstellar gas dynamics. The
resulting properties of the circumstellar medium are then used to calculate the
deceleration of a relativistic, gas-dynamic jet and the corresponding afterglow
light curve produced as the shock wave propagates through the shocked-wind
medium. We find that variations in the stellar wind drive instabilities that
may produce radial filaments in the shocked-wind region. These comet-like tails
of clumps could give rise to strong temporal variations in the early afterglow
lightcurve. Afterglows may be expected to differ widely among themselves,
depending on the angular anisotropy of the jet and the properties of the
stellar progenitor; a wide diversity of behaviors may be the rule, rather than
the exception.


title: High Resolution X-ray Spectroscopy of SN 1006

abstract:
  I discuss the high resolution XMM-Newton Reflection Grating Spectrometer
(RGS) spectrum of SN1006. SN1006 is one of the best examples of a supernova
remnant that is far out of ionization equilibrium. Moreover, optical, UV and
X-ray data indicate that it is also out of temperature equilibrium. I discuss
the X-ray evidence for this.
  In addition I discuss the lower resolution RGS spectrum of the eastern rim of
SN 1006. Despite the lower resolution, the spectrum contains significant
evidence for an asymmetric expansion velocity. Two likely solutions fit the O
VII triplet. One with no significant thermal broadening and a shell velocity of
\~6500 km/s, and one with significant broadening and a shell velocity of ~9500
km/s. The first solution seems the most plausible, as it is consistent with
radio expansion measurements, which suggest a decelerated shell.


title: Gamma-Ray Spectral State Transitions of GRO J1719-24

abstract:
  We report BATSE earth-occultation observations of the long-term soft
gamma-ray (30 keV - 1.7 MeV) flux and spectral variability of the transient
source GRO J1719-24 covering a 1000-day period between 13 January 1993 and 10
October 1995. During this period, the source underwent a major outburst in the
fall of 1993 when the 35-100 keV flux rose from a quiescent state of less than
16 mCrab before 17 September 1993 to a level of 1.5 Crab on 3 October and
remained approximately at this level over the next ~70 days. It then decreased
sharply to the pre-transition quiescent level of ~44 mCrab on 21 December where
it remained until 5 September 1994. During a 400-day period between 5 September
1994 and 10 October 1995, the source again underwent a series of five
transitions when the 35-100 keV flux increased to low-intensity levels of
\~200-400 mCrab. The low-state spectra were generally characterized by a power
law with spectral index of ~2. The high-state spectra on the other hand have
two components: a thermal Comptonized shape below ~200 keV with electron
temperature kTe of ~37 keV and optical depth of ~2.8, and a soft power-law tail
with photon index of ~3.4 above 200 keV that extends to ~500 keV. The softer
high-intensity spectrum and the harder low-intensity spectrum intercept at ~400
keV. The non-thermal power-law gamma-ray component seen in both the high and
low-intensity spectra suggests that the persistent non-thermal emission source
is coupled to the hot and variable thermal emission source in the system. This
is similar to that seen in two other gamma-ray emitting black-hole candidates
GRO J0422+32 and Cygnus X-1, suggesting that perhaps similar system
configurations and processes are occurring in these systems.


title: Planetary Nebulae in NGC 5128 (Centaurus A)

abstract:
  The study of planetary nebulae (PNe) in the nearby post-merger elliptical
galaxy NGC 5128 (Cen A) now has a history of nearly twenty years. As the
nearest giant elliptical, it is a prime target for extragalactic PN studies.
These studies have addressed many issues including the galaxy's distance, dark
matter content, halo structure, merger history, and stellar populations. We
review the main PN studies that have been conducted in NGC 5128, and introduce
a new study where we measure the [NII]/H-alpha ratio for 134 PNe. We find that
there are no PNe in our sample that are obviously of Type I, supporting the
idea that the last major star formation event in the galaxy halo occurred over
1-2 Gyr ago.


title: The 2003 Superoutburst of an SU UMa-type Dwarf Nova, GO Comae Berenices

abstract:
  We photometrically observed the 2003 June superoutburst of GO Gom. The mean
superhump period was 0.063059(13) d. The resultant data revealed that (1) the
obtained light curve contained a precursor, (2) a plateau stage of the object
lasted 8 days, which is remarkably shorter than that of ordinary SU UMa-type
dwarf novae, and (3) the amplitude of the superoutburst was less than 5 mag,
which is unpredictably small when taking into account the fact that the
supercycle of GO Com is about 2800 days. In order to explain these anomalies, a
mass elimination process from the accretion disk, such as evaporation, may play
an important role.


title: Bow shock and radio halo in the merging cluster A520

abstract:
  Chandra observations of the merging galaxy cluster A520 reveal a prominent
bow shock with M=2.1+0.4-0.3. This is only the second clear example of a
substantially supersonic merger shock front in clusters. Comparison of the
X-ray image with that of the previously known radio halo reveals a coincidence
of the leading edge of the halo with the bow shock, offering an interesting
experimental setup for determining the role of shocks in the radio halo
generation. The halo in A520 apparently consists of two spatially distinct
parts, the main turbulence-driven component and a cap-like forward structure
related to the shock, where the latter may provide pre-energized electrons for
subsequent turbulent re-acceleration. The radio edge may be caused by electron
acceleration by the shock. If so, the synchrotron spectrum should have a slope
of 1.2 right behind the edge with quick steepening further away from the edge.
Alternatively, if shocks are inefficient accelerators, the radio edge may be
explained by an increase in the magnetic field and density of pre-existing
relativistic electrons due to gas compression. In the latter model, there
should be radio emission in front of the shock with the same spectrum as that
behind it, but 10-20 times fainter. If future sensitive radio measurements do
not find such pre-shock emission, then the electrons are indeed accelerated (or
re-accelerated) by the shock, and one will be able to determine its
acceleration efficiency. We also propose a method to estimate the magnetic
field strength behind the shock, based on measuring the dependence of the radio
spectral slope upon the distance from the shock. In addition, the radio edge
provides a way to constrain the diffusion speed of the relativistic electrons.


title:
The Disruption of Stellar Clusters Containing Massive Black Holes near
  the Galactic Center

abstract:
  We present results from dynamical Monte Carlo simulations of dense star
clusters near the Galactic center. These clusters sink toward the center of the
Galaxy by dynamical friction. During their inspiral, they may undergo core
collapse and form an intermediate-mass black hole through runaway collisions.
Such a cluster can then reach within a parsec of the Galactic center before it
completely disrupts, releasing many young stars in this region. This scenario
provides a natural explanation for the presence of the young stars observed
near the Galactic center. Here we determine the initial conditions for this
scenario to work and we derive the mass distribution of cluster stars as a
function of distance from the Galactic center. For reasonable initial
conditions, we find that clusters massive enough for rapid inspiral would
include more massive stars (m >~ 30 Msun) than currently observed in the
inspiral region. We point out several possible explanations for this apparent
discrepancy.


title:
VLT-UVES observations of the Balmer line variations of eta Carinae
  during the 2003 spectroscopic event

abstract:
  We present high spectral resolution echelle observations of the Balmer line
variations during the 2003.5 ``spectroscopic event'' of eta Carinae. Spectra
have been recorded of both eta Carinae and the Homunculus at the FOS4 position
in its SE lobe. This spot shows a reflected stellar spectrum which is less
contaminated by nebular emission lines than ground-based observations of the
central object itself. Our observations show that the spectroscopic event is
much less pronounced at this position than when seen directly on eta Car using
HST/STIS. Assuming that the reflected spectrum is indeed latitude dependent
this indicates that the spectral changes during the event seen pole-on (FOS4)
are different from those closer to the equator (directly on the star). In
contrast to the spectrum of the star, the scattered spectrum of FOS4 always
shows pronounced P Cygni absorption with little variation across the
``spectroscopic event''. After that event an additional high-velocity
absorption component appears. The emission profile is more peaked at FOS4 and
consists of at least 3 distinct components, of which the reddest one shows the
strongest changes through the event. The data seem to be compatible with
changes in latitudinal wind structure of a single star, with or without the
help of a secondary star, or the onset of a shell ejection during the
spectroscopic event.


title: Yields of rotating stars at solar metallicity

abstract:
  We present a new set of stellar yields obtained from rotating stellar models
at solar metallicity covering the massive star range (12-60 solar masses). The
stellar models were calculated with the latest version of the Geneva stellar
evolution code described in Hirschi et al (2004). Evolution and nucleosynthesis
are in general followed up to silicon burning. The yields of our non-rotating
models are consistent with other calculations and differences can be understood
in the light of the treatment of convection and the rate used for C12(a,g)O16.
This verifies the accuracy of our calculations and gives a safe basis for
studying the effects of rotation on the yields.
  The contributions from stellar winds and supernova explosions to the stellar
yields are presented separately. We then add the two contributions to compute
the total stellar yields. Below about 30 solar masses, rotation increases the
total metal yields, Z, and in particular the yields of carbon and oxygen by a
factor of 1.5-2.5. As a rule of thumb, the yields of a rotating 20 solar masses
star are similar to the yields of a non-rotating 30 solar masses star, at least
for the light elements considered in this work. For very massive stars (around
60 solar masses), rotation increases the yield of helium but does not
significantly affect the yields of heavy elements.


title: V1647 Orionis (IRAS 05436-0007) : A New Look at McNeil's Nebula

abstract:
  We present a study of the newly discovered McNeil's nebula in Orion using the
JHKs-band simultaneous observations with the near-infrared (NIR) camera SIRIUS
on the IRSF 1.4m telescope. The cometary infrared nebula is clearly seen
extending toward north and south from the NIR source (V1647 Orionis) that
illuminates McNeil's nebula. The compact nebula has an apparent diameter of
about 70 arcsec. The nebula is blue (bright in J) and has a cavity structure
with two rims extending toward north-east and north-west. The north-east rim is
brighter and sharp, while the north-west rim is diffuse. The north-east rim can
be traced out to ~ 40 arcsec from the location of the NIR source. In contrast,
no cavity structure is seen toward the south, although diffuse nebula is
extended out to ~ 20 arcsec. New NIR photometric data show a significant
variation in the magnitudes (> 0.15 mag) of the source of McNeil's nebula
within a period of one week, that is possibly under the phase of eruptive
variables like FUors or EXors.


title: Laboratory and space spectroscopy of DCO+

abstract:
  The rotational spectra of DCO+ and its two isotopomers D{13}^CO+ and
DC{18}^O+, produced in a negative glow discharge cell, have been recorded in
the 137-792 GHz region, which includes lines from J=2-1 up to J=11-10. The
determined rotational and centrifugal distortion constants allow to predict the
DCO+ rotational spectrum up to 1000 GHz with an accuracy of 1 part in 10^8 or
better. This is important for kinematic studies of dense molecular cloud cores
and for future far-infrared observations. We also report on the first detection
of the hyperfine structure of the DCO+(1-0) line made at the IRAM 30m antenna,
toward the quiescent starless cloud core L1512, in the Taurus Molecular Cloud.
We point out that this is the first observation of the hyperfine splitting due
to the deuteron. This allowed us to quantify the effects of the hyperfine
splitting on the line width determination; if the hyperfine structure is not
taken into account in the line fit, the DCO+(1-0) line width is overestimated
by a significant factor (> 2).


title: Simulations of the relativistic parsec-scale jet in 3C273

abstract:
  We present a hydrodynamical 3D simulation of the relativistic jet in 3C273,
in comparison to previous linear perturbation analysis of Kelvin-Helmholtz
instability developing in the jet. Our aim is to assess advantages and
limitations of both analytical and numerical approaches and to identify spatial
and temporal scales on which the linear regime of Kelvin-Helmholtz instability
can be applied in studies of morphology and kinematics of parsec-scale jets.


title:
Densification of the International Celestial Reference Frame: Results of
  EVN Observations

abstract:
  The current realization of the International Celestial Reference Frame (ICRF)
comprises a total of 717 extragalactic radio sources distributed over the
entire sky. An observing program has been developed to densify the ICRF in the
northern sky using the European VLBI network (EVN) and other radio telescopes
in Spitsbergen, Canada and USA. Altogether, 150 new sources selected from the
Jodrell Bank-VLA Astrometric Survey were observed during three such EVN+
experiments conducted in 2000, 2002 and 2003. The sources were selected on the
basis of their sky location in order to fill the "empty" regions of the frame.
A secondary criterion was based on source compactness to limit structural
effects in the astrometric measurements. All 150 new sources have been
successfully detected and the precision of the estimated coordinates in right
ascension and declination is better than 1 milliarcsecond (mas) for most of
them. A comparison with the astrometric positions from the Very Long baseline
Array Calibrator Survey for 129 common sources indicates agreement within 2 mas
for 80% of the sources.


title: Numerical Results on Low Mass Star and Brown Dwarf Multiplicity

abstract:
  We have undertaken a series of hydrodynamic + N-body simulations in order to
explore the properties of young stars. Our results suggest that the IMF may be
sensitive to environment in its substellar region, with more brown dwarfs being
formed where clusters are denser or more compact. We find that multiple stars
are a natural outcome of collapsing turbulent flows, with a high incidence of N
> 2 multiples. We find a positive correlation of multiplicity with primary mass
but a companion frequency that decreases with age. Binary brown dwarfs are
rarely formed, in conflict with observations. Brown dwarfs as companions are
predominantly found orbiting binaries or triples at large separations.


title:
Discovery of a Large Scale Clumpy Structure around the Lynx Supercluster
  at z~1.27

abstract:
  We report the discovery of a probable large scale structure composed of many
galaxy clumps around the known twin clusters at z=1.26 and z=1.27 in the Lynx
region. Our analysis is based on deep, panoramic, and multi-colour imaging
(26.4'x24.1') in VRi'z'-bands with the Suprime-Cam on the 8.2m Subaru
telescope. This unique, deep and wide-field imaging data-set allows us for the
first time to map out the galaxy distribution in the highest redshift
supercluster known. We apply a photometric redshift technique to extract
plausible cluster members at z~1.27 down to i'=26.15 (5sigma) corresponding to
\~M*+2.5 at this redshift. From the 2-D distribution of these photometrically
selected galaxies, we newly identify seven candidates of galaxy groups or
clusters where the surface density of red galaxies is significantly high
(>5sigma), in addition to the two known clusters. These candidates show clear
red colour-magnitude sequences consistent with a passive evolution model, which
suggests the existence of additional high density regions around the Lynx
superclusters.


title: First VLBI mapping of a rare SiO isotopic substitution

abstract:
  We report the first VLBI map of the 7 mm v=0 J=1-0 maser line of the 29-SiO
isotopic substitution in the long period variable star IRC+10011. We have found
that this maser emission is composed of multiple features distributed in an
incomplete ring, suggesting that this maser is also amplified tangentially as
already proposed in other SiO circumstellar masers. We present also the results
for some 28-SiO 7 mm and 3 mm maser lines. We confirm in this epoch that the 86
GHz maser v=1 J=2-1 in IRC+10011 is formed in an outer region of the
circumstellar envelope compared to the other SiO masers studied. The 29-SiO
masing region appears to be located in a layer in between the 28-SiO v=1 J=1-0
and 28-SiO v=1 J=2-1 lines. Finally, we discuss the possible implications of
the observational results in the SiO maser pumping theory.


title:
White dwarfs with jets as non-relativistic analogues of quasars and
  microquasars?

abstract:
  We explore the similarities between accreting white dwarfs (CH Cyg and MWC
560) and the much more energetic jet sources - quasars and microquasars.
To-date we have identified several common attributes: (1) they exhibit
collimated outflows (jets); (2) the jets are precessing; (3) these two
symbiotic stars exhibit quasar-like emission line spectra; (4) there is a
disk-jet connection like that observed in microquasars. Additionally they may
have a similar energy source (extraction of rotational energy from the
accreting object). Study of the low energy analogues could have important
implications for our understanding of their higher energy cousins.


title: Planetary Transits of TRES-1

abstract:
  Observations of TRES-1b transits made during the late summer and fall 2004
observing season reveal a statistically significant but low amplitude
brightening event during egress.


title: Carbon burning in intermediate mass primordial stars

abstract:
  The evolution of a zero metallicity 9 M_s star is computed, analyzed and
compared with that of a solar metallicity star of identical ZAMS mass. Our
computations range from the main sequence until the formation of a massive
oxygen-neon white dwarf. Special attention has been payed to carbon burning in
conditions of partial degeneracy as well as to the subsequent thermally pulsing
Super-AGB phase. The latter develops in a fashion very similar to that of a
solar metallicity 9 M_s star, as a consequence of the significant enrichment in
metals of the stellar envelope that ensues due to the so-called third dredge-up
episode. The abundances in mass of the main isotopes in the final ONe core
resulting from the evolution are X(^{16}O) approx 0.59, X(^{20}Ne) approx 0.28
and X(^{24}Mg) approx 0.05. This core is surrounded by a 0.05 M_s buffer mainly
composed of carbon and oxygen, and on top of it a He envelope of mass 10^{-4}
M_s


title:
mm VLBA Observations of SiO masers: probing the close stellar
  environment of the PPN OH231.8+4.2

abstract:
  We present milliarsecond-resolution maps of the SiO maser emission v=1 J=2-1
(3 mm) in the bipolar post-AGB nebula OH231.8+4.2, and compare them with our
previous observations of the v=2 J=1-0 line (7 mm). Our observations show that
the SiO masers arise in several bright spots forming a structure elongated in a
direction perpendicular to the symmetry axis of the nebula. This, and the
complex velocity gradient observed, is consistent with the presence of an
equatorial torus in rotation and with an infall of material towards the star.


title: A layered model for non-thermal radio emission from single O stars

abstract:
  We present a model for the non-thermal radio emission from bright O stars, in
terms of synchrotron emission from wind-embedded shocks. The model is an
extension of an earlier one, with an improved treatment of the cooling of
relativistic electrons. This improvement limits the synchrotron-emitting volume
to a series of fairly narrow layers behind the shocks. We show that the width
of these layers increases with increasing wavelength, which has important
consequences for the shape of the spectrum. We also show that the strongest
shocks produce the bulk of the emission, so that the emergent radio flux can be
adequately described as coming from a small number of shocks, or even from a
single shock.
  A single shock model is completely determined by four parameters: the
position of the shock, the compression ratio and velocity jump of the shock,
and the surface magnetic field. Applying a single shock model to the O5 If star
Cyg OB2 No. 9 allows a good determination of the compression ratio and shock
position and, to a lesser extent, the magnetic field and velocity jump.
  Our main conclusion is that strong shocks need to survive out to distances of
a few hundred stellar radii. Even with multiple shocks, the shocks needed to
explain the observed emission are stronger than predictions from time-dependent
hydrodynamical simulations.


title: Applications of precision astrometry to studies of massive YSOs

abstract:
  We present VLBI observations of the H$_2$O maser emission towards a selection
of massive young stellar objects (YSOs). In one of these sources,
IRAS20126+4104, the measured proper motions confirm that the water masers spots
are tracing the very root (around 100 AU) of a conical bipolar outflow emerging
near the position of the embedded YSO, and are an excellent tool to investigate
the structure and kinematics of the outflow/jet. We also present preliminary
results of a first epoch EVN observations of a selection of 5 high-mass YSO to
assess the precise association of maser spots and molecular outflows in these
sources.


title: Primary Versus Secondary Leptons in the EGRET SNR's

abstract:
  The EGRET supernova remnants (SNR's) are all expanding into nearby dense
molecular clouds, powering a shock at the interface where protons and electrons
accelerate to relativistic energies. A viable mechanism for the emission of
gamma$-rays in these sources is the decay of neutral pions created in
collisions between the relativistic hadrons and protons in the ambient medium.
But neutral pion decay alone cannot reproduce the whole high-energy spectrum,
particularly below 100 MeV. A pion-decay scenario thus requires a lepton
population to "fill in" the lower part of the spectrum via bremsstrahlung
emission. This population, however, is constrained by the SNR radio spectrum.
Taking our cue from the behavior of Sgr A East, an energetic EGRET SNR at the
Galactic center, we here examine the role played in these sources by secondary
leptons--electrons and positrons produced in proton-proton scattering events
and the ensuing particle cascades. We show that while secondary leptons cannot
account for the gamma-rays below 100 MeV, they can account for the hard radio
spectra observed from the EGRET SNR's. Thus, it appears that both primary and
secondary leptons may be important contributors to the overall broadband
emission from these sources, but if so, must radiate most of their energy in
different parts of the SNR-cloud environment. We show that shock acceleration
in dense cores being overtaken by the expanding SNR shell can naturally lead to
such a scenario.


title: Analysis strategies and software for geodetic VLBI

abstract:
  This article describes currently used analysis strategy and data analysis
software for geodetic VLBI.Today's geodetic observing strategies are shortly
presented, and the geodetic VLBI observables and data modeling are briefly
discussed. A short overview is given on existing geodetic VLBI software
packages and the statistical approaches that are applied. Necessary
improvements of today's analysis software are described. Some of the future
expectations and goals of geodetic VLBI are presented and the corresponding
consequences for the VLBI technique are explained. This includes consequences
in terms of technical development and corresponding improvements in data
modeling and analysis software.


title: Multi-frequency imaging in VLBI

abstract:
  The new technique, multi-frequency imaging (MFI) is developed. In VLBI,
Multi-Frequency Imaging (MFI) consists of multi-frequency synthesis (MFS) and
multi-frequency analysis (MFA) of the VLBI data obtained from observations on
various frequencies. A set of linear deconvolution MFI algorithms is described.
The algorithms make it possible to obtain high quality images interpolated on
any given frequency inside any given bandwidth, and to derive reliable
estimates of spectral indexes for radio sources with continuum spectrum. Thus
MFI approach makes it is possible not only to improve the quality and fidelity
of the images and also essentially to derive the morphology of the observed
radio sources.


title: Multi-wavelength differential astrometry of the S5 polar cap sample

abstract:
  We report on the status of our S5 polar cap astrometry program. Since 1997 we
have observed all the 13 radio sources of the complete S5 polar cap sample at
the wavelengths of 3.6 cm, 2 cm and 7 mm. Images of the radio sources at 3.6
and 2 cm have already been published reporting morphological changes.
Preliminary astrometric analyses have been carried out at three frequencies
with precisions in the relative position determination ranging from 80 to 20
microarcseconds. We report also on the combination of our phase-delay global
astrometry results with the microarcsecond-precise optical astrometry that will
be provided by future space-based instruments.


title: EVN Observations of the BL Lac object ON 231

abstract:
  New EVN images at 5.0 GHz and 8.4 GHz of ON 231 confirm the complex structure
of the source, the identification of the core, the presence of components on
the two sides of the core itself and a low brightness extension South-East of
the main jet. The optical behaviour of the source is discussed in connection to
changes in the radio structure.


title: Evn, Merlin, and Vla Observations of Nrao530

abstract:
  We present images of NRAO530 observed with the EVN (VLBI) at 5 GHz, the
MERLIN at 1 .6 and 5 GHz, and the VLA at 5 and 8 GHz showing the complex
morphology on scales from pc to kpc. The VLBI image shows a core-jet structure
indicating a somehow oscillation trajectory on a scale of 30 mas, north to the
strongest compact component (core). A core-jet structure extended to several
hundreds mas at about P.A. -50 deg and a distant component located 11 arcsec
west to the core are detected in both the MERLIN and the VLA observations. An
arched structure of significant emission between the core and the distant
component is also revealed in both the MERLIN image at 1.6 cm and the VLA
images at 8.4 and 5 GHz. The core component shows a flat spectrum with alpha =
-0.02 (S proportional to the frequency power -alpha) while alpha = 0.8 for the
distant component. The steep spectrum of the distant component and the
detection of the arched emission suggests that the western distant component is
a lobe or a hot-spot powered by the nucleus of NRAO530. A patch of diffuse
emission, 12 arcsec nearly east (P.A. = 70 deg) to the core component, is also
observed with the VLA at 5 GHz, suggesting a presence of a counter lobe in the
source.


title:
The dust SED in the dwarf galaxy NGC 1569: Indications for an altered
  dust composition?

abstract:
  We discuss the interpretation of the dust SED from the mid-infrared to the
millimeter range of NGC 1569. The model developed by D\'esert et al. (1990)
including three dust components (Polyaromatic Hydrocarbons, Very Small Grains
and big grains) can explain the data using a realistic interstellar radiation
field and adopting an enhanced abundance of VSGs. A simple three-temperature
model is also able to reproduce the data but requires a very low dust
temperature which is considered to be unlikely in this low-metallicity
starburst galaxy. The high abundance of Very Small Grains might be due to large
grain destruction in supernova shocks. This possibility is supported by ISO
data showing that the emission at 14.3 $\mu$m, tracing VSGs, is enhanced with
respect to the emission at 6.7 $\mu$m and 850 $\mu$m in regions of high star
formation.


title:
Cluster mergers and non-thermal phenomena: expectations from a
  statistical magneto-turbulent model

abstract:
  The most important evidences for non-thermal phenomena in galaxy clusters
comes from the spectacular synchrotron radio emission diffused over Mpc scale
observed in a growing number of massive clusters. A promising possibility to
explain giant radio halos is given by the presence of relativistic electrons
reaccelerated by some kind of turbulence generated in the cluster volume during
merger events. With the aim to investigate the connection between thermal and
non-thermal properties of the ICM, in this paper we develope a statistical
magneto-turbulent model which describes in a self-consistent way the evolution
of the thermal ICM and that of the non-thermal emission from clusters. Making
use of the extended Press & Schechter formalism, we follow cluster mergers and
estimate the injection rate of the fluid turbulence generated during these
energetic events. We then calculate the evolution of the spectrum of the
relativistic electrons in the ICM during the cluster life by taking into
account both the electron-acceleration due to the merger-driven turbulence and
the relevant energy losses of the electrons. We end up with a synthetic
population of galaxy clusters for which the evolution of the ICM and of the
non-thermal spectrum emitted by the accelerated electrons is calculated. The
generation of detectable non-thermal radio and hard X-ray emission in the
simulated clusters is found to be possible during major merger events for
reliable values of the model parameters. In addition the occurrence of radio
halos as a function of the mass of the parent clusters is calculated and
compared with observations. In this case it is found that the model
expectations are in good agreement with observations.


title:
Complete Multiwavelength Characterization of Faint Chandra X-ray Sources
  Seen in the Spitzer Wide-Area IR Extragalactic (SWIRE) Survey

abstract:
  We exploit deep combined observations with Spitzer and Chandra of the SWIRE
survey in the ELAIS-N1 region, to investigate the nature of the faint X-ray and
IR sources in common, to identify AGN/starburst diagnostics, and to study the
sources of the X-ray and IR cosmic backgrounds. In the 17'x17' area of the
Chandra ACIS-I image there are 3400 SWIRE near-IR sources with 4 sigma
detections in at least 2 IRAC bands and 988 sources detected at 24micron with
MIPS brighter than 0.1 mJy. Of these, 102 IRAC and 59 MIPS sources have Chandra
counterparts, out of a total of 122 X-ray sources present in the area with
S(0.5-8 kev)>10^(-15) erg/cm^2/s. We have constructed SEDs for each source
using data from the 4 IRAC wavebands, Chandra fluxes, and optical follow-up
data in the wavebands U, g', r', i', Z, and H. We fit a number of spectral
templates to the SEDs at optical and infrared wavelengths to determine
photometric redshifts and spectral categories, and also make use of diagnostics
based on the X-ray luminosities, hardness ratios, X-ray to infrared spectral
slopes and optical morphologies. Although we have spectroscopic redshifts for
only a minority of the Chandra sources, the available SEDs constrain the
redshifts for most of the sample sources, which turn out to be typically at
0.5<z<2. We find that 39% of the Chandra sources are dominated by type-1 AGN
emission, 23% display optical/IR spectra typical of type-2 AGNs, while the
remaining 38% fraction show starburst-like or even normal galaxy spectra. Since
we prove that all these galaxies are dominated by AGN emission in X-rays this
brings the fraction of type-1 AGNs to be 80% of the type-2: even assuming that
all the Chandra sources undetected by Spitzer are type-2 AGNs, the type-1
fraction would exceed 1/3 of the total population (abridged).


title: CMB Fluctuation Amplitude from Dark Energy Partitions

abstract:
  It is assumed that the dark energy observed today is frozen as a result of a
phase transition involving the source of that energy. Postulating that the dark
energy de-coherence which results from this phase transition drives statistical
variations in the energy density specifies a class of cosmological models in
which the cosmic microwave background (CMB) fluctuation amplitude at last
scattering is approximately $10^{-5}$.


title: Environmental Impact on the Southeast Limb of the Cygnus Loop

abstract:
  We analyze observations from the Chandra X-ray Observatory of the southeast
knot of the Cygnus Loop supernova remnant. In this region, the blast wave
propagates through an inhomogeneous environment. Extrinsic differences and
subsequent multiple projections along the line of sight rather than intrinsic
shock variations, such as fluid instabilities, account for the apparent
complexity of the images. Interactions between the supernova blast wave and
density enhancements of a large interstellar cloud can produce the
morphological and spectral characteristics. Most of the X-ray flux arises in
such interactions, not in the diffuse interior of the supernova remnant.
Additional observations at optical and radio wavelengths support this account
of the existing interstellar medium and its role in shaping the Cygnus Loop,
and they demonstrate that the southeast knot is not a small cloud that the
blast wave has engulfed. These data are consistent with rapid equilibration of
electron and ion temperatures behind the shock front, and the current blast
wave velocity v_{bw} approx 330 km/s. Most of this area does not show strong
evidence for non-equilibrium ionization conditions, which may be a consequence
of the high densities of the bright emission regions.


title: Induced galaxy formation

abstract:
  We describe the model of protogalaxy formation around the cluster of
primordial black holes with a minimum extension of standard cosmological model.
Namely, it is supposed, that a mass fraction of the universe ~10^-3 is composed
of the compact clusters of primordial (relict) black holes produced during the
phase transitions in the early universe. These clusters are the centers of the
dark matter (DM) condensations. As a result the protogalaxies with a mass
2x10^8Msun form at the redshift z=15. These induced protogalaxies contain the
central black holes of mass ~10^5Msun and look like the dwarf spheroidal
galaxies with a central density spike. Subsequent merging of the induced
protogalaxies and ordinary DM haloes leads to the standard scenario of the
large scale structure formation. Black holes merging gives the nowadays
supermassive black holes and reproduces the observed correlations between their
masses and velocity dispersions in the bulges.


title:
Bootstrap resampling as a tool for radio-interferometric imaging
  fidelity assessment

abstract:
  We report on a numerical evaluation of the statistical bootstrap as a
technique for radio-interferometric imaging fidelity assessment. The
development of a fidelity assessment technique is an important scientific
prerequisite for automated pipeline reduction of data from modern radio
interferometers. We evaluate the statistical performance of two bootstrap
methods, the model-based bootstrap and subsample bootstrap, against a Monte
Carlo parametric simulation, using interferometric polarization calibration and
imaging as the representative problem under study. We find both statistical
resampling techniques to be viable approaches to radio-interferometric imaging
fidelity assessment which merit further investigation. We also report on the
development and implementation of a new self-calibration algorithm for
radio-interferometric polarimetry which makes no approximations for the
polarization source model.


title: Semi-empirical analysis of SDSS galaxies: I. Spectral synthesis method

abstract:
  In this paper we investigate the power of spectral synthesis as a mean to
estimate physical properties of galaxies. Spectral synthesis is nothing more
than the decomposition of an observed spectrum in terms of a superposition of a
base of simple stellar populations of various ages and metallicities, producing
as output the star-formation and chemical histories of a galaxy, its extinction
and velocity dispersion. Our implementation of this method uses the Bruzual &
Charlot (2003) models and observed spectra in the 3650--8000 \AA range. The
reliability of this approach is studied by three different means: (1)
simulations, (2) comparison with previous work based on a different technique,
and (3) analysis of the consistency of results obtained for a sample of
galaxies from the SDSS. We find that spectral synthesis provides reliable
physical parameters as long as one does not attempt a very detailed description
of the star-formation and chemical histories. We show that besides providing
excellent fits to observed galaxy spectra, this method is able to recover
useful information on the distributions of stellar ages and, more importantly,
stellar metallicities. Stellar masses, velocity dispersion and extinction are
also found to be accurately retrieved for realistic signal-to-noise ratios. We
apply this synthesis method to a volume limited sample of 50362 galaxies from
the SDSS DR2, producing a catalog of stellar population properties. A
comparison with recent estimates of both observed and physical properties of
these galaxies obtained by other groups shows good qualitative and quantitative
agreement. The confidence in the method is further strengthened by several
empirical and astrophysically reasonable correlations between synthesis results
and independent quantities.


title:
Emission measure distribution in loops impulsively heated at the
  foot-points

abstract:
  This work is prompted by the evidence of sharply peaked emission measure
distributions in active stars, and by the claims of isothermal loops in solar
coronal observations, at variance with the predictions of hydrostatic loop
models with constant cross-section and uniform heating. We address the problem
with loops heated at the foot-points. Since steady heating does not allow
static loop models solutions, we explore whether pulse-heated loops can exist
and appear as steady loops, on a time average. We simulate pulse-heated loops,
using the Palermo-Harvard 1-D hydrodynamic code, for different initial
conditions corresponding to typical coronal temperatures of stars ranging from
intermediate to active ($T \sim 3$--$10 \times 10^6$ K). We find long-lived
quasi-steady solutions even for heating concentrated at the foot-points over a
spatial region of the order of $\sim 1/5$ of the loop half length and
broader.These solutions yield an emission measure distribution with a peak at
high temperature, and the cool side of the peak is as steep as $\sim T^{5}$, in
contrast to the usual $\sim T^{3/2}$ of hydrostatic models with constant
cross-section and uniform heating. Such peaks are similar to those found in the
emission measure distribution of active stars around $10^7$ K.


title: Late Time Observations of the Afterglow and Environment of GRB 030329

abstract:
  We present Very Long Baseline Interferometry (VLBI) observations 217 days
after the gamma-ray burst of 2003 March 29. These observations provide further
measurements of the size and position of GRB 030329 that are used to constrain
the expansion rate and proper motion of this nearby GRB. The expansion rate
appears to be slowing down with time, favoring expansion into a constant
density interstellar medium, rather than a circumstellar wind with an r^-2
density profile. We also present late time Arecibo observations of the
redshifted HI and OH absorption spectra towards GRB 030329. No absorption (or
emission) is seen allowing us to place limits on the atomic neutral hydrogen of
N_H < 8.5 x 10^20 cm^-2, and molecular hydrogen of N_H_2 < 1.4 x 10^22 cm^-2.
Finally, we present VLA limits on the radio polarization from the afterglow of
<2% at late times.


title: Kinematics in Hickson Compact Group 90

abstract:
  Using long-slit spectra observed at the VLT (ESO, Paranal) in May 2002, we
studied the stellar kinematics in the core of the Hickson Compact Group 90. The
line of sight velocity distribution (LOSVD), the velocity dispersion profiles
and the Hermite moments h3,h4 along two slit positions are presented. The
comparison with previous results is discussed. For kinematical analysis we used
the parametrization for the LOSVD given in van der Marel et al. (1993).


title:
Highly Ionized Gas in the Galactic Halo and the High Velocity Clouds
  Toward PG 1116+215

abstract:
  We have obtained high resolution FUSE and HST/STIS echelle observations of
the quasar PG 1116+215. The semi-continuous coverage of the ultraviolet
spectrum over the wavelength range 916-2800 provides detections of Galactic and
high velocity cloud (HVC) absorption over a wide range of ionization species
over the local standard of rest velocity range -100 - +200 km/s. The high
dispersion of these spectra (6.5-20 km/s) reveals that low ionization species
consist of five discrete components, three at low-to-intermediate velocities,
and two at high velocities (v = +100, +184 km/s). Over the same velocity range,
the higher ionization species show continuous absorption with column density
peaks at v = +10 km/s +184 km/s. The absorption kinematics of the v=+184 km/s
HVC suggest a scenario in which a low-ionization cloud of gas is streaming
through a hot external medium that is stripping gas from this cloud. Using the
OI and HI column densities, we estimate [O/H]=-0.66, with a substantial
uncertainty due to saturation of the HI Lyman series. If the ionization of the
cloud core is photonionization by the extragalactic UV background, we estimate
the cloud has a density of 10^-2.7 cm^-3. If photons escaping the Galactic disk
are also included, the density could be higher by nearly 2 dex. In either case,
the relative abundances of O, Si, and Fe in the cloud core are readily
explained by a solar pattern. Magellanic Stream gas is a possible origin for
this gas and is consistent with the location of the HVC on the sky, as well as
its high positive velocity, the ionization, and metallicity. [Abridged]


title: Radio Relics in Clusters of Galaxies

abstract:
  In this paper we review the observational results on Relic radio sources in
clusters of galaxies. We discuss their observational properties, structures and
radio spectra. We will show that Relics can be divided according to their size,
morphology, and location in the galaxy cluster. These differences could be
related to physical properties of Relic sources. The comparison with cluster
conditions suggests that Relics could be related to shock waves originated by
cluster mergers.


title: On the Progenitor of the Type II Supernova 2004et in NGC 6946

abstract:
  Supernova (SN) 2004et is the eighth historical SN in the nearby spiral galaxy
NGC 6946. Here we report on early photometric and spectroscopic monitoring of
this object. SN 2004et is a Type II event, exhibiting a plateau in its light
curves, but its spectral and color evolution appear to differ significantly
from those of other, more normal Type II-plateau (II-P) SNe. We have analyzed
Canada-France-Hawaii Telescope (CFHT) images of the host galaxy taken prior to
the SN explosion, identifying a candidate progenitor for the SN. The star's
absolute magnitude and intrinsic color imply that it was a yellow, rather than
red, supergiant star, with an estimated zero-age main sequence mass of
$15^{+5}_{-2} M_\odot$. Although this mass estimate is consistent with
estimates and upper limits for the progenitors of other, more normal SNe II-P,
the SN 2004et progenitor's unusual color could further imply a pre-explosion
evolutionary history analogous to, but less extreme than, that for the
progenitors of the peculiar Type II-P SN 1987A or the Type IIb SN 1993J. The
identity of the progenitor candidate needs to be verified when the SN has
significantly dimmed.