title:
Rejecting Astrophysical False Positives from the TrES Transiting Planet
  Survey: The Example of GSC 03885-00829

abstract:
  Ground-based wide-field surveys for nearby transiting gas giants are yielding
far fewer true planets than astrophysical false positives, of which some are
difficult to reject. Recent experience has highlighted the need for careful
analysis to eliminate astronomical systems where light from a faint eclipsing
binary is blended with that from a bright star. During the course of the
Trans-atlantic Exoplanet Survey, we identified a system presenting a
transit-like periodic signal. We obtained the proper motion and infrared color
of this target (GSC 03885-00829) from publicly available catalogs, which
suggested this star is an F dwarf, supporting our transit hypothesis. This
spectral classification was confirmed using spectroscopic observations from
which we determined the stellar radial velocity. The star did not exhibit any
signs of a stellar mass companion. However, subsequent multi-color photometry
displayed a color-dependent transit depth, indicating that a blend was the
likely source of the eclipse. We successfully modeled our initial photometric
observations of GSC 03885-00829 as the light from a K dwarf binary system
superimposed on the light from a late F dwarf star. High-dispersion
spectroscopy confirmed the presence of light from a cool stellar photosphere in
the spectrum of this system. With this candidate, we demonstrate both the
difficulty in identifying certain types of false positives in a list of
candidate transiting planets and our procedure for rejecting these imposters,
which may be useful to other groups performing wide-field transit surveys.


title: Distribution of Positron Annihilation Radiation

abstract:
  The SPI instrument on-board the ESA/INTEGRAL satellite is engaged in a
mission-long study of positron annihilation radiation from the Galaxy. Early
results suggest that the disk component is only weakly detected at 511 keV by
SPI. We review CGRO/OSSE, TGRS and SMM studies of 511 keV line and positronium
continuum emission from the Galaxy in light of the early INTEGRAL/SPI findings.
We find that when similar spatial distributions are compared, combined fits to
the OSSE/SMM/TGRS data-sets produce bulge and disk fluxes similar in total flux
and in B/D ratio to the fits reported for SPI observations. We further find
that the 511 keV line width reported by SPI is similar to the values reported
by TGRS, particularly when spectral fits include both narrow-line and
broad-line components. Collectively, the consistency between these four
instruments suggests that all may be providing an accurate view of positron
annihilation in the Galaxy.


title:
Determination Of The Orbit Of The Planetary Companion To The Metal Rich
  Star HD 45350

abstract:
  We present the precise radial velocity (RV) data for the metal-rich star HD
45350 collected with the Harlan J. Smith (HJS) 2.7 m telescope and the
Hobby-Eberly Telescope (HET) at McDonald Observatory. This star was noticed by
us as a candidate for having a giant planetary companion in a highly eccentric
orbit, but the lack of data close to periastron left the amplitude and thus
mass of the planet poorly constrained. Marcy et al. (2005) announced the
presence of the planet based on their Keck/HIRES data, but those authors also
cautioned that the remaining uncertainties in the orbital solution might be
large due to insufficient data near periastron passage. In order to close this
phase gap we exploited the flexible queue scheduled observing mode of the HET
to obtain intensive coverage of the most recent periastron passage of the
planet. In combination with the long term data from the HJS 2.7 m telescope we
determine a Keplerian orbital solution for this system with a period of 962
days, an eccentricity of e=0.76 and a velocity semi-amplitude K of 57.4 m/s.
The planet has a minimum mass of m sin i = 1.82 +- 0.14 M_Jup and an orbital
semi-major axis of a = 1.92 +-0.07 AU.


title: Evolution of the periodicities in 2S 0114+650

abstract:
  We have analysed nine years of data from the All Sky Monitor on the Rossi
X-ray Timing Explorer for 2S 0114+650 to study the evolution of its spin,
binary and super-orbital periods. The spin history of the neutron star in this
system exhibits torque reversals lasting ~1 yr. The newly discovered
super-orbital period has remained stable over the 9-yr span, making 2S 0114+650
the fourth known system to exhibit stable super-orbital modulation. We compare
its super-orbital period evolution with those of the other three such systems.


title: On the difference between nuclear and contraction ages

abstract:
  Context:Ages derived from the low mass stars still contracting onto the main
sequence often differ from ages derived from the high mass ones that have
already evolved away from it.
  Aims:We investigate the general claim of disagreement between these two
independent age determinations by presenting UBVRI photometry of the young
galactic open clusters NGC 2232, NGC 2516, NGC 2547 and NGC 4755, spanning the
age range ~10-150 Myr
  Methods: We derive reddenings, distances and nuclear ages by fitting ZAMS and
isochrones to color-magnitudes and color-color diagrams. To derive contraction
ages, we use four different pre-main sequence models, with an empirically
calibrated color-temperature relation to match the Pleiades cluster sequence.
  Results: When using exclusively the V vs. V-I color-magnitude diagram and
empirically calibrated isochrones, there is consistency between nuclear and
contraction ages for the studied clusters. Although the contraction ages seem
systematically underestimated, in none of cases they deviate by more than one
standard deviation from the nuclear ages.


title:
Modeling Eclipses in the Classical Nova V Persei: The Role of the
  Accretion Disk Rim

abstract:
  Multicolor (BVRI) light curves of the eclipsing classical nova V Per are
presented, and a total of twelve new eclipse timings are measured for the
system. When combined with previous eclipse timings from the literature, these
timings yield a revised ephemeris for the times of mid-eclipse given by HJD =
2,447,442.8260(1) + 0.107123474(3) E. The eclipse profiles are analyzed with a
parameter-fitting model that assumes four sources of luminosity: a white dwarf
primary star, a main-sequence secondary star, a flared accretion disk with a
rim, and a bright spot at the intersection of the mass-transfer stream and the
disk periphery. A matrix of model solutions are computed, covering an extensive
range of plausible parameter values. The solution matrix is then explored to
determine the optimum values for the fitting parameters and their associated
errors. For models that treat the accretion disk as a flat structure without a
rim, optimum fits require that the disk have a flat temperature profile.
Although models with a truncated inner disk (R_in >> R_wd) result in a steeper
temperature profile, steady-state models with a temperature profile
characterized by T(r) \propto r^{-3/4} are found only for models with a
significant disk rim. A comparison of the observed brightness and color at
mid-eclipse with the photometric properties of the best-fitting model suggests
that V Per lies at a distance of ~ 1 kpc.


title:
Magnetic Field Confinement in the Corona: The Role of Magnetic Helicity
  Accumulation

abstract:
  A loss of magnetic field confinement is believed to be the cause of coronal
mass ejections (CMEs), a major form of solar activity in the corona. The
mechanisms for magnetic energy storage are crucial in understanding how a field
may possess enough free energy to overcome the Aly limit and open up.
Previously, we have pointed out that the accumulation of magnetic helicity in
the corona plays a significant role in storing magnetic energy. In this paper,
we investigate another hydromagnetic consequence of magnetic-helicity
accumulation. We propose a conjecture that there is an upper bound on the total
magnetic helicity that a force-free field can contain. This is directly related
to the hydromagnetic property that force-free fields in unbounded space have to
be self-confining. Although a mathematical proof of this conjecture for any
field configuration is formidable, its plausibility can be demonstrated with
the properties of several families of power-law, axisymmetric force-free
fields. We put forth mathematical evidence, as well as numerical, indicating
that an upper bound on the magnetic helicity may exist for such fields. Thus,
the accumulation of magnetic helicity in excess of this upper bound would
initiate a non-equilibrium situation, resulting in a CME expulsion as a natural
product of coronal evolution.


title: Why the braking indices of young pulsars are less than 3?

abstract:
  In this letter we discuss two possible reasons which cause the observed
braking indices n of young radio pulsars to be smaller than 3: (a) the evolving
spin-down model of the magnetic field component $B_{\perp}$ increases with
time; (b) the extrinsic braking torque model in which the tidal torques exerted
on the pulsar by the fallback disk, and carries away the spin angular momentum
from the pulsar. Based on some simple assumptions, we derive the expression of
the braking indices, and calculate the spin-down evolutionary tracks of pulsars
for different input parameters.


title:
Multiwavelength Observations of 1ES 1959+650, One Year After the Strong
  Outburst of 2002

abstract:
  In April-May 2003, the blazar 1ES 1959+650 showed an increased level of X-ray
activity. This prompted a multiwavelength observation campaign with the Whipple
10 m gamma-ray telescope, the Rossi X-ray Timing Explorer, the Bordeaux Optical
Observatory, and the University of Michigan Radio Astrophysical Observatory. We
present the multiwavelength data taken from May 2, 2003 to June 7, 2003 and
compare the source characteristics with those measured during observations
taken during the years 2000 and 2002. The X-ray observations gave a data set
with high signal-to-noise light curves and energy spectra; however, the
gamma-ray observations did not reveal a major TeV gamma-ray flare. Furthermore,
we find that the radio and optical fluxes do not show statistically significant
deviations from those measured during the 2002 flaring periods. While the X-ray
flux and X-ray photon index appear correlated during subsequent observations,
the apparent correlation evolved significantly between the years 2000, 2002,
and 2003. We discuss the implications of this finding for the mechanism that
causes the flaring activity.


title:
Outflow Driven Cavities: Numerical Simulations of Intermediaries of
  Protostellar Turbulence

abstract:
  We investigate the evolution of fossil cavities produced by extinct YSO jets
and wide angle outflows. Fossil cavities are ellipsoidal or cylindrical shells
of swept-up of ambient (molecular cloud) material moving at low velocities. The
cavities form when the momentum in a YSO jet or wide angle outflow decays in
time allowing the bowshock or swept-up shell to decelerate to velocities near
the turbulent speed in the cloud. It has been suggested in previous studies
that cavities provide efficient coupling between the jets/outflows and the
cloud and, as such, are the agents by which cloud turbulence is can be
re-energized. In this paper we carry forward a series of numerical simulations
of jets and outflows whose momentum flux decrease in time. We compare
simulations with decaying momentum fluxes to those with constant flux. We show
that decaying flux models exhibit deceleration of the outflow head and
backfilling via expansion off of the cavity walls. They also have lower density
contrast, are longer lived and wider than their continuously driven
counterparts. The simulations recover the basic properties of observed fossil
cavities. In addition, we provide synthetic observations in terms of P-V
diagrams which demonstrate that fossil cavities form both jets and wide angle
outflows are characterized by linear "Hubble-law" expansions patterns
superimposed on "spur" patterns indicative of the head of a bow shock.


title:
Astrometric accuracy of phase-referenced observations with the VLBA and
  EVN

abstract:
  Astrometric accuracy of complex modern VLBI arrays cannot be calculated
analytically. We study the astrometric accuracy of phase-referenced VLBI
observations for the VLBA, EVN and global VLBI array by simulating VLBI data
for targets at declinations -25$^\circ$, 0$^\circ$, 25$^\circ$, 50$^\circ$,
75$^\circ$ and 85$^\circ$. The systematic error components considered in this
study are calibrator position, station coordinate, Earth orientation and
troposphere parameter uncertainties. We provide complete tables of the
astrometric accuracies of these arrays for a source separation of 1$^\circ$
either along the right ascension axis or along the declination axis.
Astrometric accuracy is 50microas at mid declination and is 300microas at low
(-25$^\circ$) and high (85$^\circ$) declinations for the VLBA and EVN. In
extending our simulations to source separations of 0.5$^\circ$ and 2$^\circ$,
we establish the formula for the astrometric accuracy of the VLBA: Delta =
(Delta_1$^\circ$-14)*d+ 14 (microas) where Delta_1$^\circ$ is the astrometric
accuracy for a separation d=1$^\circ$ provided in our tables for various
declinations and conditions of the wet troposphere. We argue that this formula
is also valid for the astrometric accuracy of the EVN and global VLBI array.


title: The consistency equation hierarchy in single-field inflation models

abstract:
  Inflationary consistency equations relate the scalar and tensor
perturbations. We elucidate the infinite hierarchy of consistency equations of
single-field inflation, the first of which is the well-known relation
A_T^2/A_S^2 = -n_T/2 between the amplitudes and the tensor spectral index. We
write a general expression for all consistency equations both to first and
second-order in the slow-roll expansion. We discuss the relation to other
consistency equations that have appeared in the literature, in particular
demonstrating that the approximate consistency equation recently introduced by
Chung and collaborators is equivalent to the second consistency equation of
Lidsey et al. (1997).


title:
Radio and infrared recombination studies of the southern massive
  star-forming region G333.6-0.2

abstract:
  We present high spatial resolution radio and near-infrared hydrogen
recombination line observations of the southern massive star-forming region
G333.6-0.2. The 3.4-cm continuum peak is found slightly offset from the
infrared source. The H90alpha spectra show for the first time a double peak
profile at some positions. The complex velocity structure may be accounted for
by champagne outflows, which may also explain the offset between the radio and
infrared sources. The 2.17-um Brackett gamma image and H90alpha map are
combined to construct an extinction map which shows a trend probably set by the
blister nature of the HII region. The total number of Lyman continuum photons
in the central 50-arcsec is estimated to be equivalent to that emitted by up to
19 O7V stars.


title:
Extreme Deuteration and Hot Corinos: the Earliest Chemical Signatures of
  Low-Mass Star Formation

abstract:
  Low-mass protostars form from condensations inside molecular clouds when
gravity overwhelms thermal and magnetic supporting forces. The first phases of
the formation of a solar-type star are characterized by dramatic changes not
only in the physical structure but also in the chemical composition. Since PPIV
(e.g., Langer et al.), exciting new developments have occurred in our
understanding of the processes driving this chemical evolution. These
developments include two new discoveries : 1) extremely enhanced molecular
deuteration, which is caused by the freeze-out of heavy-element-bearing
molecules onto grain mantles during the Prestellar Core and Class 0 source
phases; and 2) hot corinos, which are warm and dense regions at the center of
Class 0 source envelopes and which are characterized by a multitude of complex
organic molecules. In this chapter we will review these two new topics, and
will show how they contribute to our understanding of the first phases of
solar-type stars.


title: Measuring neutrino masses and dark energy with weak lensing tomography

abstract:
  Surveys of weak gravitational lensing of distant galaxies will be one of the
key cosmological probes in the future. We study the ability of such surveys to
constrain neutrino masses and the equation of state parameter of the dark
energy, focussing on how tomographic information can improve the sensitivity to
these parameters. We also provide a detailed discussion of systematic effects
pertinent to weak lensing surveys, and the possible degradation of sensitivity
to cosmological parameters due to these effects. For future probes such as the
Large Synoptic Survey Telescope survey, we find that, when combined with cosmic
microwave background data from the Planck satellite, a sensitivity to neutrino
masses of sigma(sum m_nu) < 0.05 eV can be reached. This results is robust
against variations in the running of the scalar spectral index, the
time-dependence of dark energy equation of state, and/or the number of
relativistic degrees of freedom.


title:
Does rotation of B stars depend on metallicity? preliminary results from
  GIRAFFE spectra

abstract:
  We show the vsini distribution of main sequence B stars in sites of various
metallicities, in the absolute magnitude range -3.34 < Mv < -2.17. These
include Galactic stars in the field measured by Abt et al. (2002), members of
the h & chi Per open clusters measured by North et al. (2004), and five fields
in the SMC and LMC measured at ESO Paranal with the FLAMES-GIRAFFE
spectrograph, within the Geneva-Lausanne guaranteed time. Following the
suggestion by Maeder et al. (1999), we do find a higher rate of rapid rotators
in the Magellanic Clouds than in the Galaxy, but the vsini distribution is the
same in the LMC and in the SMC in spite of their very different metallicities.


title: Discovery of Very-High-Energy Gamma-Rays from the Galactic Centre Ridge

abstract:
  The origin of Galactic cosmic rays (with energies up to 10^15 eV) remains
unclear, though it is widely believed that they originate in the shock waves of
expanding supernova remnants. Currently the best way to investigate their
acceleration and propagation is by observing the gamma-rays produced when
cosmic rays interact with interstellar gas. Here we report observations of an
extended region of very high energy (VHE, >100 GeV) gamma-ray emission
correlated spatially with a complex of giant molecular clouds in the central
200 pc of the Milky Way. The hardness of the gamma-ray spectrum and the
conditions in those molecular clouds indicate that the cosmic rays giving rise
to the gamma-rays are likely to be protons and nuclei rather than electrons.
The energy associated with the cosmic rays could have come from a single
supernova explosion around 10,000 years ago.


title:
Gamma rays from dark matter annihilation in the Draco and observability
  at ARGO

abstract:
  The CACTUS experiment recently observed a gamma ray excess above 50 GeV from
the direction of the Draco dwarf spheroidal galaxy. Considering that Draco is
dark matter dominated the gamma rays may be generated through dark matter
annihilation in the Draco halo. In the framework of the minimal supersymmetric
extension of the standard model we explore the parameter space to account for
the gamma ray signals at CACTUS. We find that the neutralino mass is
constrained to be approximately in the range between 100 GeV ~ 400 GeV and a
sharp central cuspy of the dark halo profile in Draco is necessary to explain
the CACTUS results. We then discuss further constraints on the supersymmetric
parameter space by observations at the ground based ARGO detector. It is found
that the parameter space can be strongly constrained by ARGO if no excess from
Draco is observed above 100 GeV.


title:
VLA H53alpha and H92alpha line observations of the central region of NGC
  253

abstract:
  We present new Very Large Array (VLA) observations toward NGC 253 of the
recombination line H53alpha (43 GHz) at an angular resolution of 1.''5 X 1.''0.
The free-free emission at 43 GHz is estimated to be ~100 mJy, implying a star
formation rate of ~1.3 Msun/yr in the nuclear region of this starburst galaxy.
A reanalysis is made for previously reported H92alpha observations carried out
with angular resolution of 1.''5 X 1.''0 and 0.''36 X 0.''21. Based on the line
and continuum emission models used for the 1.''5 X 1.''0 angular resolution
observations, the RRLs H53alpha and H92alpha are tracers of the high-density
(~10^5 cm-3) and low-density (~10^3 cm^-3) thermally ionized gas components in
NGC 253, respectively. The velocity fields observed in the H53alpha and
H92alpha lines 1.''5 X 1.''0) are consistent. The velocity gradient in the
central ~18 pc of the NE component, as observed in both the H53alpha and
H92alpha lines, is in the opposite direction to the velocity gradient
determined from the CO observations. The enclosed virial mass, as deduced from
the H53alpha velocity gradient over the NE component, is ~5 X 10^6 Msun in the
central ~18 pc region. The H92alpha line observations at high angular
resolution (0.''36 X 0.''21) reveal a larger velocity gradient, along a P.A. ~
-45 deg on the NE component, of ~110 km/s/arcsec. The dynamical mass estimated
using the high angular resolution H92alpha data (~7 X 10^6 Msun) supports the
existence of an accreted massive object in the nuclear region of NGC 253.


title: Spectral and Fourier analyses of X-ray QPO in accreting black holes

abstract:
  We study energy dependencies of quasi-periodic oscillations from a number of
black hole X-ray binaries. The selected sources were observed by RXTE at time
periods close to state transitions and showed QPO in the 1-10 Hz range. We have
constructed QPO root-mean-square energy spectra, which provide information
about underlying physical processes leading to QPO generation. These spectra
show an interesting anti-correlation with the time averaged spectra. The QPO
r.m.s. spectra are harder than the time averaged spectra when the latter are
soft, while they are softer than the time averaged spectra when the latter are
hard. We then discuss these observational results in the context of simple
spectral variability models. Hard QPO spectra can be produced by quasi-periodic
modulations of the heating rate of the Comptonizing plasma, while soft QPO
spectra result from modulations of the cooling rate by soft photons.


title:
The Type IIn Supernova 2002kg: The Outburst of a Luminous Blue Variable
  Star in NGC 2403

abstract:
  We show that Supernova (SN) 2002kg in NGC 2403, initially classified as Type
II-narrow (IIn), has photometric and spectroscopic properties unlike those of
normal SNe. Its behavior, instead, is more typical of highly massive stars
which experience the short-lived luminous blue variable (LBV) phase toward the
end of their lives. The star, in fact, most resembles the LBV S Doradus in
outburst. The precursor of SN 2002kg is the irregular, bright blue variable
star 37 (V37), catalogued by Tammann & Sandage in 1968. Using high-quality
ground-based, multi-band images we can constrain the initial mass of V37 to be
M_ini >~ 40 M_sun. We find that, although the spectra indicate a nitrogen
enhancement, possibly revealing the products of CNO processing by V37 in the
ejecta, the star lacks a substantial LBV nebula. The outburst from SN
2002kg/V37 is not nearly as energetic as the giant eruptions of the eta
Carinae-like variables, such as SN 1954J/V12, also in NGC 2403. SN 2002kg/V37,
however, is among a growing number of ``SN impostors'' exhibiting a broad range
of outburst energetics during a pre-SN phase of massive-star evolution.


title: Radiation Feedback and Fragmentation in Massive Protostellar Cores

abstract:
  Star formation generally proceeds inside-out, with overdense regions inside
protostellar cores collapsing rapidly and progressively less dense regions
following later. Consequently, a small protostar will form early in the
evolution of a core, and collapsing material will fall to the protostellar
surface and radiate away its gravitational potential energy. The resulting
accretion luminosity will heat the core and may substantially affect the
process of fragmentation. This is of particular interest for massive cores
that, at their initial temperatures, have masses much greater than a thermal
Jeans mass and thus might be expected to fragment into many stars during
collapse. Here I show that accretion luminosity can heat the inner parts of a
core to >100 K very early in the star formation process, and that this in turn
strongly suppresses fragmentation. This has implications for a number of
outstanding problems in star formation, including the mechanism of massive star
formation, the origin of the stellar initial mass function and its relationship
to the core mass function, the demographics of massive binaries, and the
equation of state in star-forming gas.


title:
Chandra X-Ray Observations of Young Clusters. III. NGC 2264 and the
  Orion Flanking Fields

abstract:
  Chandra observations of solar-like pre-main sequence (PMS) stars in the Orion
Flanking Fields (age ~1 Myr) and NGC 2264 (~3 Myr) are compared with the
results of the COUP survey of similar objects in the ONC (~0.5 Myr). The
correlations between log Lx and mass found for PMS stars on convective tracks
in these clusters are consistent with the relationships found for the ONC,
indicating little change in the median values of either log Lx or log Lx/Lbol
during the first ~3-5 Myr of evolution down convective tracks. The fraction of
stars with extreme values of Lx, more than 10 times higher than the average for
a given Lbol or with log Lx/Lbol greater than the canonical saturation value of
-2.9, is however larger by a factor of two in the younger ONC when compared
with the Orion FF and NGC 2264.
  PMS stars in NGC 2264 on radiative tracks have Lx/Lbol values that are
systematically lower by a factor of ~10 times than those found for stars of
similar mass on convective tracks. The dramatic decrease in flux from
convective to radiative phases of PMS evolution is likely related to major
structural changes which influence the efficiency of magnetic field generation
and thus the level of magnetic activity.
  As in the ONC, we find that stars with measured periods have, on average,
higher X-ray luminosities. However, there is a wide range in Lx and Lx/Lbol for
both periodic and non-periodic stars of similar mass. Among stars with measured
periods, the level of X-ray emission does not correlate with the rotation rate.
  For this data set, we find no statistically significant correlation between
X-ray flux and (a) the presence or absence of circumstellar accretion disks, or
(b) disk accretion rates as assessed from ultraviolet excesses.


title: Local Ultraluminous Infrared Galaxies and Quasars

abstract:
  This paper reviews the recent results from a comprehensive investigation of
the most luminous mergers in the local universe, the ultraluminous infrared
galaxies (ULIRGs) and the quasars. First, the frequency of occurrence and
importance of black hole driven nuclear activity in ULIRGs are discussed using
the latest sets of optical, near-infrared, mid-infrared, and X-ray spectra on
these objects. Obvious trends with luminosity, infrared color, and morphology
are pointed out. Next, the host galaxy properties of ULIRGs are described in
detail and then compared with local quasar hosts and inactive spheroids. By and
large, these data are consistent with the scenario where ULIRGs are
intermediate-mass elliptical galaxies in formation and in the process of
becoming moderate-luminosity optical quasars. The powerful galactic winds
detected in many ULIRGs may help shed any excess gas during this
transformation. However, this evolutionary scenario does not seem to apply to
all ULIRGs and quasars: Ultraluminous infrared mergers do not always result in
a quasar, and low-luminosity quasars near the boundary with Seyferts do not all
show signs of a recent major merger.


title: A ULX microquasar in NGC 5408?

abstract:
  We studied the radio source associated with the ultraluminous X-ray source in
NGC 5408 (L_X ~ 10^{40} erg/s). The radio spectrum is steep (index ~ -1),
consistent with optically-thin synchrotron emission, not with flat-spectrum
core emission. Its flux density (~ 0.28 mJy at 4.8 GHz, at a distance of 4.8
Mpc) was the same in the March 2000 and December 2004 observations, suggesting
steady emission rather than a transient outburst. However, it is orders of
magnitude higher than expected from steady jets in stellar-mass microquasar.
Based on its radio flux and spectral index, we suggest that the radio source is
either an unusually bright supernova remnant, or, more likely, a radio lobe
powered by a jet from the black hole. Moreover, there is speculative evidence
that the source is marginally resolved with a radius ~ 30 pc. A faint HII
region of similar size appears to coincide with the radio and X-ray sources,
but its ionization mechanism remains unclear. Using a self-similar solution for
the expansion of a jet-powered electron-positron plasma bubble, in the
minimum-energy approximation, we show that the observed flux and (speculative)
size are consistent with an average jet power ~ 7 x 10^{38} erg/s ~ 0.1 L_X ~
0.1 L_{Edd}, an age ~ 10^5 yr, a current velocity of expansion ~ 80 km/s. We
briefly discuss the importance of this source as a key to understand the
balance between luminosity and jet power in accreting black holes.


title:
Hard TeV spectra of blazars and the constraints to the IR intergalactic
  background

abstract:
  Recent gamma-ray observations of the blazar 1ES 1101-232 (redshift z=0.186)
reveal that the unabsorbed TeV spectrum is hard, with spectral index $\alpha
\lesssim 0.5$ [$F(\nu) \propto \nu^{-\alpha}$]. We show that simple one-zone
synchrotron self-Compton model can explain such hard spectra if we assume a
power law energy distribution of the emitting electrons with a relatively high
minimum energy. In this case the intrinsic TeV spectrum can be as hard as
$F(\nu)\propto \nu^{1/3}$, while the predicted X-ray spectrum can still be much
softer. The observations of 1ES 1101-232 can therefore be reconciled with
relatively high intensities of the infrared background, even if some extreme
background levels can indeed be excluded. We show that the other TeV sources
(Mrk 421, Mrk 501 and PKS 2155-304) can be interpreted in the same framework,
with a somewhat larger minimum energy.


title: Ultraluminous Infrared Galaxies

abstract:
  Ever since their discovery in the 1970's, UltraLuminous InfraRed Galaxies
(ULIRGs; classically Lir>10^12Lsun) have fascinated astronomers with their
immense luminosities, and frustrated them due to their singularly opaque
nature, almost in equal measure. Over the last decade, however, comprehensive
observations from the X-ray through to the radio have produced a consensus
picture of local ULIRGs, showing that they are mergers between gas rich
galaxies, where the interaction triggers some combination of dust-enshrouded
starburst and AGN activity, with the starburst usually dominating. Very recent
results have thrown ULIRGs even further to the fore. Originally they were
thought of as little more than a local oddity, but the latest IR surveys have
shown that ULIRGs are vastly more numerous at high redshift, and tantalizing
suggestions of physical differences between high and low redshift ULIRGs hint
at differences in their formation modes and local environment. In this review
we look at recent progress on understanding the physics and evolution of local
ULIRGs, the contribution of high redshift ULIRGs to the cosmic infrared
background and the global history of star formation, and the role of ULIRGs as
diagnostics of the formation of massive galaxies and large-scale structures.


title:
The Effects of Interactions on the Structure and Morphology of
  Elliptical/Lenticular galaxies in Pairs

abstract:
  We present a photometric and structural analysis of 42 E/S0 galaxies in (E/S0
+ S) pairs observed in the BVRI color bands. We empirically determine the
effects of interactions on their morphology, structure and stellar populations
as seen from the light concentration (C), asymmetry (A), and clumpiness (S)
parameters. We further compare these values to a control sample of 67 mostly
isolated, non-interacting E/S0 galaxies. The paired E/S0 galaxies occupy a more
scattered loci in CAS space than non-interacting E/S0's, and the structural
effects of interactions on E/S0's are minor, in contrast to disk galaxies
involved in interactions. This suggests that observational methods for
recognizing interactions at high z, such the CAS methodology, would hardly
detect E/S0's involved in interactions (related to early phases of the so
called `dry-mergers'). We however find statistical differences in A when
comparing isolated and interacting E/S0s. In the mean, paired E/S0 galaxies
have A values 2.96+-0.72 times larger than the ones of non-interacting E/S0's.
For the subset of presumably strongly interacting E/S0's, A and S can be
several times larger than the typical values of the isolated E/S0's. We show
that the asymmetries are consistent with several internal and external
morphological distortions. We conclude that the interacting E/S0s in pairs
should be dense, gas poor galaxies in systems spaning a wide range of
interaction stages, with typical merging timescales >~ 0.1-0.5 Gyr. We use the
observed phenomenology of these galaxies to predict the approximate loci of
`dry pre-mergers' in the CAS space.(Abridged)


title:
Lens-Aided Multi-Angle Spectroscopy (LAMAS) Reveals Small-Scale Outflow
  Structure in Quasars

abstract:
  Spectral differences between lensed quasar image components are common. Since
lensing is intrinsically achromatic, these differences are typically explained
as the effect of either microlensing, or as light path time delays sampling
intrinsic quasar spectral variability. Here we advance a novel third
hypothesis: some spectral differences are due to small line-of-sight
differences through quasar disk wind outflows. In particular, we propose that
variable spectral differences seen only in component A of the widest separation
lens SDSSJ1004+4112 are due to differential absorption along the sightlines.
The absorber properties required by this hypothesis are akin to known broad
absorption line (BAL) outflows but must have a broader, smoother velocity
profile. We interpret the observed CIV emission line variability as further
evidence for spatial fine structure transverse to the line of sight. Since
outflows are likely to be rotating, such absorber fine structure can
consistently explain some of the UV and X-ray variability seen in AGN. The
implications are many: (1) Spectroscopic differences in other lensed objects
may be due to this ``lens-aided multi-angle spectroscopy'' (LAMAS). (2)
Outflows have fine structure on size scales of arcsec as seen from the nucleus.
(3) Assuming either broad absorption line region sizes proposed in recent wind
models, or typically assumed continuum emission region sizes, LAMAS and/or
variability provide broadly consistent absorber sizescale estimates of about
10^15cm. (4) Very broad smooth absorption may be ubiquitous in quasar spectra,
even when no obvious troughs are seen.


title:
Protoneutron star dynamos: pulsars, magnetars, and radio-silent X-ray
  emitting neutron stars

abstract:
  We discuss the mean-field dynamo action in protoneutron stars that are
subject to instabilities during the early evolutionary phase. The mean field is
generated in the neutron-finger unstable region where the Rossby number is
$\sim 1$ and mean-field dynamo is efficient. Depending on the rotation rate,
the mean-field dynamo can lead to the formation of three different types of
pulsars. If the initial period of the protoneutron star is short, then the
generated large-scale field is very strong ($> 3 \times 10^{13}$G) and exceeds
the small-scale field at the neutron star surface. If rotation is moderate,
then the pulsars are formed with more or less standard dipole fields ($< 3
\times 10^{13}$G) but with surface small-scale magnetic fields stronger than
the dipole field. If rotation is very slow, then the mean-field dynamo does not
operate, and the neutron star has no global field. Nevertheless, strong
small-scale fields are generated in such pulsars, and they can manifest
themselves as objects with very low spin-down rate but with a strong magnetic
field inferred from the spectral features.


title: Dust Stratification in Young Circumstellar Disks

abstract:
  We present high-resolution infrared spectra of four YSOs (T Tau N, T Tau S,
RNO 91, and HL Tau). The spectra exhibit narrow absorption lines of 12CO, 13CO,
and C18O as well as broad emission lines of gas phase12CO. The narrow
absorption lines of CO are shown to originate from the colder circumstellar
gas. We find that the line of sight gas column densities resulting from the CO
absorption lines are much higher than expected for the measured extinction for
each source and suggest the gas to dust ratio is measuring the dust settling
and/or grain coagulation in these extended disks. We provide a model of
turbulence, dust settling and grain growth to explain the results. The
techniques presented here allow us to provide some observationally-motivated
bounds on accretion disk alpha in protostellar systems.


title: Theoretical light curves for deflagration models of Type Ia supernova

abstract:
  We present synthetic bolometric and broad-band UBVRI light curves of SNe Ia,
for four selected 3-D deflagration models of thermonuclear supernovae. The
light curves are computed with the 1-D hydro code STELLA, which models
(multi-group time-dependent) non-equilibrium radiative transfer inside SN
ejecta. Angle-averaged results from 3-D hydrodynamical explosion simulations
with the composition determined in a nucleosynthetic postprocessing step served
as the input to the radiative transfer model. The predicted model UBV light
curves do agree reasonably well with the observed ones for SNe Ia in the range
of low to normal luminosities, although the underlying hydrodynamical explosion
models produced only a modest amount of radioactive Ni56 and relatively low
kinetic energy in the explosion. The evolution of predicted B and V fluxes in
the model with a Ni56 mass of 0.42 M_sun follows the observed decline rate
after the maximum very well, although the behavior of fluxes in other filters
somewhat deviates from observations, and the bolometric decline rate is a bit
slow. Using our models, we check the validity of Arnett's rule and the accuracy
of the procedure for extracting the Ni56 mass from the observed light curves.
We find that the comparison between theoretical light curves and observations
provides a useful tool to validate SN Ia models. The steps necessary to improve
the agreement between theory and observations are set out.


title: Profile morphology and polarization of young pulsars

abstract:
  We present polarization profiles at 1.4 and 3.1 GHz for 14 young pulsars with
characteristic ages less than 75 kyr. Careful calibration ensures that the
absolute position angle of the linearly polarized radiation at the pulsar is
obtained. In combination with previously published data we draw three main
conclusions about the pulse profiles of young pulsars. (1) Pulse profiles are
simple and consist of either one or two prominent components. (2) The linearly
polarized fraction is nearly always in excess of 70 per cent. (3) In profiles
with two components the trailing component nearly always dominates, only the
trailing component shows circular polarization and the position angle swing is
generally flat across the leading component and steep across the trailing
component.
  Based on these results we can make the following generalisations about the
emission beams of young pulsars. (1) There is a single, relatively wide cone of
emission from near the last open field lines. (2) Core emission is absent or
rather weak. (3) The height of the emission is between 1 and 10 per cent of the
light cylinder radius.


title: Comment Regarding the Functional Form of the Schmidt Law

abstract:
  Star formation rates on the galactic scale are described phenomenologically
by two distinct relationships, as emphasized recently by Elmegreen (2002). The
first of these is the Schmidt law, which is a power-law relation between the
star formation rate and the column density. The other relationship is that
there is a cutoff in the gas density below which star formation shuts off.
  The purpose of this paper is to argue that 1) these two relationships can be
accommodated by a single functional form of the Schmidt law, and 2) this
functional form is motivated by the hypothesis that star formation is a
critical phenomenon, and that as a corollary, 3) the existence of a sharp
cutoff may thus be an emergent property of galaxies, as was argued by Seiden
(1983), as opposed to the classical view that this cutoff is due to an
instability criterion.


title:
The origin of the lead-rich stars in Galactic halo: investigation of the
  model parameters for the s-process

abstract:
  Several stars at the low-metallicity extreme of the Galactic halo show large
spreads of [Pb/hs]. Theoretically, a s-process pattern should be obtained from
an AGB star with fixed metallicity and initial mass. For the third dredge-up
and the s-process model, several important properties depend primarily on the
core mass of AGB stars. Zijlstra (2004) reported that the initial-final-mass
relation steepens at low metallicity, due to low mass-loss efficiency. This
perhaps affects the model parameters of the AGB stars, e.g. the overlap factor
and the neutron irradiation time, in particular at low metallicity. The
calculated results show indeed that the overlap factor and the neutron
irradiation time are significantly small at low metallicities, especially for
3.0Msun AGB stars. The scatter of [Pb/hs] found in low metallicities can
therefore be explained naturally when varying the initial mass of the low-mass
AGB stars.


title: Secure Identification of Free-Floating Planets

abstract:
  Among the methods proposed to detect extrasolar planets, microlensing is the
only technique that can detect free-floating planets. Free-floating planets are
detected through the channel of short-duration isolated lensing events.
However, if a seemingly isolated planetary event is detected, it is difficult
to firmly conclude that the event is caused by a free-floating planet because a
wide-separation planet can also produce an isolated event. There were several
methods proposed to break the degeneracy between the isolated planetary events
produced by the free-floating and wide-separation planets, but they are
incomplete. In this paper, we show that free-floating planets can be securely
identified by conducting astrometric follow-up observations of isolated events
to be detected in future photometric lensing surveys by using high-precision
interferometers to be operated contemporarily with the photometric surveys. The
method is based on the fact that astrometric lensing effect covers much longer
range of the lens-source separation than the photometric effect. We demonstrate
that several astrometric follow-up observations of isolated planetary events
associated with source stars brighter than $V\sim 19$ by using the {\it Space
Interferometry Mission} with an exposure time of $\lesssim 10 {\rm min}$ for
each observation will make it possible to measure the centroid shift induced by
primaries with projected separations up to $\sim 100 {\rm AU}$. Therefore, the
proposed method is far more complete than previously proposed methods that are
flawed by the limited applicability only to planets with projected separations
$\lesssim 20 {\rm AU}$ or planets accompanied by bright primaries.


title:
The Interstellar Medium of IRAS 08572+3915 NW: H3+ and Warm High
  Velocity CO

abstract:
  We confirm the first detection of the molecular ion H3+ in an extragalactic
object, the highly obscured ultraluminous galaxy IRAS 08572+3915 NW. We also
have detected absorption lines of the fundamental band of CO in this galaxy.
The CO absorption consists of a cold component close to the systemic velocity
and warm, highly blueshifted and redshifted components. The warm blueshifted
component is remarkably strong and broad and extends at least to -350 km/s.
Some analogies can be drawn between the H3+ and cold CO in IRAS08572+3915 NW
and the same species seen toward the Galactic center. The profiles of the warm
CO components are not those expected from a dusty torus of the type thought to
obscure active galactic nuclei. They are probably formed close to the dust
continuum surface near the buried and active nucleus and are probably
associated with an unusual and energetic event there.


title:
Galaxies Under the Cosmic Microscope: Resolved Spectroscopy and New
  Constraints on the z=1 Tully-Fisher relation

abstract:
  We exploit the gravitational potential of massive cluster lenses to probe the
emission line properties of six z=1 galaxies which appear as highly magnified
luminous arcs. Using the GMOS integral field spectrograph together with
detailed cluster lens models we reconstruct the intrinsic morphologies and
two-dimensional velocity fields in these galaxies on scales corresponds to
\~0.5kpc (unlensed) at z=1. Four of the galaxies have stable disk-like
kinematics, whilst the other two resemble interacting or starburst galaxies.
These galaxies lie close to the mean rest-frame I-band Tully-Fisher relation
for nearby spirals suggesting a clear preference for hierarchical growth of
structure. In the rest-frame B-band, the observations suggest 0.5+/-0.3mag of
brightening, consistent with increased star-formation activity at z=1. However,
the galaxies with stable disk kinematics have more slowly rising rotation
curves than expected from galaxies with similar surface brightness in the local
Universe. We suggest that this may arise because the distant galaxies have
lower bulge masses than their local counter-parts. Whilst this study is based
on only six galaxies, the gain in flux and in spatial resolution achieved via
gravitational magnification provides a much more detailed view of the high
redshift Universe than possible with conventional surveys.


title: X-ray Emitting Young Stars in the Carina Nebula

abstract:
  We present a multiwavelength study of the central part of the Carina Nebula,
including Trumpler 16 and part of Trumpler 14. Analysis of the Chandra X-ray
Observatory archival data led to the identification of nearly 450 X-ray
sources. These were then cross-identified with optical photometric and
spectroscopic information available from literature, and with deep
near-infrared (JHKs) imaging observations. A total of 38 known OB stars are
found to be X-ray emitters. All the O stars and early B stars show the nominal
relation between the X-ray and bolometric luminosities, Lx ~ 10^{-7} Lbol. A
few mid- to late-type B stars are found to be associated with X-ray emission,
likely attributable to T Tauri companions. We discovered 17 OB star candidates
which suffer large extinction in the optical wavebands. Some 300 sources have
X-ray and infrared characteristics of late-type pre-main sequence stars. Our
sample presents the most comprehensive census of the young stellar population
in the Carina Nebula and will be useful for the study of the star-formation
history of this massive star-forming region. We also report the finding of a
compact (5' X 4') group of 7 X-ray sources, all of which highly reddened in
near-infrared and most X-ray bright. The group is spatially coincident with the
dark 'V' shaped dust lane bisecting the Carina Nebula, and may be part of an
embedded association. The distribution of the young stellar groups surrounding
the HII region associated with Trumpler 16 is consistent with a triggering
process of star formation by the collect-and-collapse scenario.


title: Blind component separation for polarized observations of the CMB

abstract:
  We present in this paper the PolEMICA (Polarized Expectation-Maximization
Independent Component Analysis) algorithm which is an extension to polarization
of the SMICA (Spectral Matching Independent Component Analysis) temperature
multi-detectors multi-components (MD-MC) component separation method
(Delabrouille et al. 2003). This algorithm allows us to estimate blindly in
harmonic space multiple physical components from multi-detectors polarized sky
maps. Assuming a linear noisy mixture of components we are able to reconstruct
jointly the anisotropies electromagnetic spectra of the components for each
mode T, E and B, as well as the temperature and polarization spatial power
spectra, TT, EE, BB, TE, TB and EB for each of the physical components and for
the noise on each of the detectors. PolEMICA is specially developed to estimate
the CMB temperature and polarization power spectra from sky observations
including both CMB and foreground emissions. This has been tested intensively
using as a first approach full sky simulations of the Planck satellite
polarized channels for a 14-months nominal mission assuming a simplified linear
sky model including CMB, and optionally Galactic synchrotron emission and a
Gaussian dust emission. Finally, we have applied our algorithm to more
realistic Planck full sky simulations, including synchrotron, realistic dust
and free-free emissions.


title:
General Relativistic Magnetohydrodynamic Simulations of Jet Formation
  and Large-Scale Propagation from Black Hole Accretion Systems

abstract:
  The formation and large-scale propagation of Poynting-dominated jets produced
by accreting, rapidly rotating black hole systems are studied by numerically
integrating the general relativistic magnetohydrodynamic equations of motion to
follow the self-consistent interaction between accretion disks and black holes.
This study extends previous similar work by studying jets till $t\approx
10^4GM/c^3$ out to $r\approx 10^4GM/c^2$, by which the jet is super- fast
magnetosonic and moves at a lab-frame bulk Lorentz factor of $\Gamma\sim 10$
with a maximum terminal Lorentz factor of $\Gamma_\infty\lesssim 10^3$. The
radial structure of the Poynting-dominated jet is piece-wise self-similar, and
fits to flow quantities along the field line are provided. Beyond the \alf
surface at $r\sim 10$--$100GM/c^2$, the jet becomes marginally unstable to (at
least) current-driven instabilities. Such instabilities drive shocks in the jet
that limit the efficiency of magnetic acceleration and collimation. These
instabilities also induce jet substructure with $3\lesssim\Gamma\lesssim 15$.
The jet is shown to only marginally satisfy the necessary and sufficient
conditions for kink instability, so this may explain how astrophysical jets can
extend to large distances without completely disrupting. At large distance, the
jet angular structure is Gaussian-like (or uniform within the core with sharp
exponential wings) with a half-opening angle of $\approx 5^\circ$ and there is
an extended component out to $\approx 27^\circ$. Unlike in some hydrodynamic
simulations, the environment is found to play a negligible role in jet
structure, acceleration, and collimation as long as the ambient pressure of the
surrounding medium is small compared to the magnetic pressure in the jet.


title:
Interferometric data reduction with AMBER/VLTI.Principle,estimators and
  illustration

abstract:
  We present in this paper an innovative data reduction method for single-mode
interferometry. It has been specifically developed for the AMBER instrument,
the three-beam combiner of the Very Large Telescope Interferometer, but can be
derived for any single-mode interferometer. The algorithm is based on a direct
modelling of the fringes in the detector plane. As such, it requires a
preliminary calibration of the instrument in order to obtain the calibration
matrix which builds the linear relationship between the interferogram and the
interferometric observable, that is the complex visibility. Once the
calibration procedure has been performed, the signal processing appears to be a
classical least square determination of a linear inverse problem. From the
estimated complex visibility, we derive the squared visibility, the closure
phase and the spectral differential phase. The data reduction procedures are
gathered into the so-called amdlib software, now available for the community,
and presented in this paper. Furthermore, each step of this original algorithm
is illustrated and discussed from various on-sky observations conducted with
the VLTI, with a focus on the control of the data quality and the effective
execution of the data reduction procedures. We point out the present limited
performances of the instrument due to VLTI instrumental vibrations, difficult
to calibrate.


title: Improved Fokker-Planck Equation for Resonance Line Scattering

abstract:
  A new Fokker-Planck equation is developed for treating resonance line
scattering, especially relevant to the treatment of Lyman alpha in the early
universe. It is a "corrected" form of the equation of Rybicki & Dell'Antonio
that now obeys detailed balance, so that the approach to thermal equilibrium is
properly described. The new equation takes into account the energy changes due
to scattering off moving particles, the recoil term of Basko, and stimulated
scattering. One result is a surprising unification of the equation for
resonance line scattering and the Kompaneets equation. An improved energy
exchange formula due to resonance line scattering is derived. This formula is
compared to previous formulas of Madau, Meikson, & Rees (1997) and Chen &
Miralda-Escud\'e (2004).


title: Zodiacal Light Emission in the PLANCK mission

abstract:
  The PLANCK satellite, scheduled for launch in 2007, will produce a set of all
sky maps in nine frequency bands spanning from 30 GHz to 857 GHz, with an
unprecedented sensitivity and resolution. Planets, minor bodies and diffuse
interplanetary dust will contribute to the (sub)mm sky emission observed by
PLANCK, representing a source of foreground contamination to be removed before
extracting the cosmological information. The aim of this paper is to assess the
expected level of contamination in the survey of the forthcoming PLANCK
mission. Starting from existing far-infrared (far-IR) models of the Zodiacal
Light Emission (ZLE), we present a new method to simulate the time-dependent
level of contamination from ZLE at PLANCK frequencies. We studied the
possibility of PLANCK to detect and separate the ZLE contribution from the
other astrophysical signals. We discuss the conditions in which PLANCK will be
able to increase the existing information on the ZLE and IDP physical
properties.


title: The Square Kilometre Array: A new probe of cosmic magnetism

abstract:
  Magnetic fields are a fundamental part of many astrophysical phenomena, but
the evolution, structure and origin of magnetic fields are still unresolved
problems in physics and astrophysics. When and how were the first fields
generated? Are present-day magnetic fields the result of standard dynamo
action, or do they represent rapid or recent field amplification through other
processes? What role do magnetic fields play in turbulence, cosmic ray
acceleration and structure formation? I explain how the Square Kilometre Array
(SKA), a next-generation radio telescope, can deliver stunning new data-sets
that will address these currently unanswered issues. The foundation for these
experiments will be an all-sky survey of rotation measures, in which Faraday
rotation toward >10^7 background sources will provide a dense grid for probing
magnetism in the Milky Way, nearby galaxies, and in distant galaxies, clusters
and protogalaxies. Using these data, we can map out the evolution of magnetized
structures from redshifts z > 3 to the present, can distinguish between
different origins for seed magnetic fields in galaxies, and can develop a
detailed model of the magnetic field geometry of the intergalactic medium and
of the overall Universe. In addition, the SKA will certainly discover new
magnetic phenomena beyond what we can currently predict or imagine.


title: BVI photometry of the very old open cluster Berkeley 17

abstract:
  We have obtained BVI CCD imaging of Berkeley 17, an anticentre open cluster
that competes with NGC 6791 as the oldest known open cluster. Using the
synthetic colour magnitude diagrams (CMD) technique with three sets of
evolutionary tracks we have determined that its age is 8.5 - 9.0 Gyr, it
distance modulus is (m-M)_0 = 12.2, with a reddening of E(B-V) = 0.62 - 0.60.
Differential reddening, if present, is at the 5 % level. All these values have
been obtained using models with metallicity about half of solar (Z=0.008 or
Z=0.01 depending on the stellar evolution tracks), which allows us to reproduce
the features of the cluster CMD better than other metallicities. Finally, from
the analysis of a nearby comparison field we think to have intercepted a
portion of the disrupting Canis Major dwarf galaxy.


title: Angular Momentum Transfer in Dark Matter Halos: Erasing the Cusp

abstract:
  We propose that angular momentum transfer from the baryons to the Dark Matter
(DM) during the early stages of galaxy formation can flatten the halo inner
density profile and modify the halo dynamics. We compute the phase-space
distribution function of DM halos, that corresponds to the density and
anisotropy profiles obtained from N-body simulations in the concordance
cosmology. We then describe an injection of angular momentum into the halo by
modifying the distribution function, and show that the system evolves into a
new equilibrium configuration; the latter features a constant central density
and a tangentially-dominated anisotropy profile in the inner regions, while the
structure is nearly unchanged beyond 10% of the virial radius. Then we propose
a toy model to account for such a halo evolution, based on the angular momentum
exchange due to dynamical friction; at the epoch of galaxy formation this is
efficiently exerted by the DM onto the gas clouds spiralling down the potential
well. The comparison between the angular momentum profile gained by the halo
through dynamical friction and that provided by the perturbed distribution
function reveals a surprising similarity, hinting at the reliability of the
process.


title:
Interacting Vector-like Dark Energy, the First and Second Cosmological
  Coincidence Problems

abstract:
  One of the puzzles of the dark energy problem is the (first) cosmological
coincidence problem, namely, {\em why does our universe begin the accelerated
expansion recently? why are we living in an epoch in which the dark energy
density and the dust matter energy density are comparable?} On the other hand,
cosmological observations hint that the equation-of-state parameter (EoS) of
dark energy crossed the phantom divide $w_{de}=-1$ in the near past. Many dark
energy models whose EoS can cross the phantom divide have been proposed.
However, to our knowledge, these models with crossing the phantom divide only
provide the possibility that $w_{de}$ can cross -1. They do not answer another
question, namely, {\em why crossing the phantom divide occurs recently?} Since
in many existing models whose EoS can cross the phantom divide, $w_{de}$
undulates around -1 randomly, {\em why are we living in an epoch $w_{de}<-1$?}
This can be regarded as the second cosmological coincidence problem. In this
work, the cosmological evolution of the vector-like dark energy interacting
with background perfect fluid is investigated. We find that the first and
second cosmological coincidence problems can be alleviated at the same time in
this scenario.


title: Bayesian analysis of Friedmannless cosmologies

abstract:
  Assuming only a homogeneous and isotropic universe and using both the 'Gold'
Supernova Type Ia sample of Riess et al. and the results from the Supernova
Legacy Survey, we calculate the Bayesian evidence of a range of different
parameterizations of the deceleration parameter. We consider both spatially
flat and curved models. Our results show that although there is strong evidence
in the data for an accelerating universe, there is little evidence that the
deceleration parameter varies with redshift.


title:
Merging of Elliptical Galaxies as Possible Origin of the Intergalactic
  Stellar Population

abstract:
  We present N-body simulations of elliptical galaxy encounters into dry
mergers to study the resulting unbound intergalactic stellar population, in
particular that of the post-Main Sequence stars. The systems studied are pairs
of spherical galaxies without dark halos. The stellar content of the model
galaxies is distributed into mass-bins representing low- and intermediate-mass
stars (0.85 -- 8 solar masses) according to Salpeter's initial mass function.
Our models follow the dynamical evolution of galaxy encounters colliding
head-on from initial low-energy parabolic or high-energy mildly-hyperbolic
orbits, and for a choice of initial-mass ratios. The merging models with
initial parabolic orbits have M2/M1 =1 and 10, and they leave behind
respectively 5.5 % and 10 % of the total initial mass as unbound stellar mass.
The merging model with initial hyperbolic orbit has M2/M1 =1, and leaves behind
21 % of its initial stellar mass as unbound mass, showing that the efficiency
in producing intergalactic stars through a high-energy hyperbolic encounter is
about four times than through a parabolic encounter of the same initial mass
ratio. By assuming that all progenitor galaxies as well as the merger remnants
are homologous systems we obtained that the intergalactic starlight is 17 % and
28 % of the total starlight respectively for the parabolic and hyperbolic
encounters with M2/M1 =1. In all models, different mass stars have the same
probability of becoming unbound and feeding the intergalactic stellar
population.


title: Pierre Auger Data, Photons, and Top-Down Cosmic Ray Models

abstract:
  We consider the ultra-high energy cosmic ray (UHECR) spectrum as measured by
the Pierre Auger Observatory. Top-down models for the origin of UHECRs predict
an increasing photon component at energies above about $10^{19.7}$eV. Here we
present a simple prescription to compare the Auger data with a prediction
assuming a pure proton component or a prediction assuming a changing primary
component appropriate for a top-down model. We find that the UHECR spectrum
predicted in top-down models is a good fit to the Auger data. Eventually, Auger
will measure a composition-independent spectrum and will be capable of either
confirming or excluding the quantity of photons predicted in top-down models.


title:
Faint Supernovae and Supernova Impostors: Case studies of
  SN2002kg/NGC2403-V37 and SN 2003gm

abstract:
  Photometric and spectroscopic observations of the faint Supernovae (SNe)
2002kg and 2003gm, and their precursors, in NGC 2403 and NGC 5334 respectively,
are presented. The properties of these SNe are discussed in the context of
previously proposed scenarios for faint SNe: low mass progenitors producing
under-energetic SNe; SNe with ejecta constrained by a circumstellar medium; and
outbursts of massive Luminous Blue Variables (LBVs). The last scenario has been
referred to as ``Type V SNe'', ``SN impostors'' or ``fake SNe.'' The faint SN
2002kg reached a maximum brightness of $\mathrm{M_{V}=-9.6}$, much fainter than
normal type II SNe. The precursor of SN 2002kg is confirmed to be, as shown in
previous work, the LBV NGC2403-V37. Strong $\mathrm{Fe II}$ lines are observed
in the spectra of SN 2002kg, similar to both the LBV NGC2363-V1 and the type
IIn SN 1995G. The spectrum of SN 2002kg does show strong resolved $\mathrm{[N
II]}$ at $\lambda\lambda$6549,6583\ang. The identified progenitor of SN 2003gm
is a bright yellow star, consistent with a F5-G2 supergiant. SN 2003gm, at the
epoch of discovery, was of similar brightness to the possible fake SN 1997bs.
Photometrically SN 2003gm shows the same decrease in brightness, over the same
time period as SN 1997bs. The early time spectra of SN 2003gm are dominated by
Balmer emission lines, which at the observed resolution, appear similar to SN
2000ch. On the basis of the post-discovery photometric and spectroscopic
observations presented here we suggest that SN 2003gm is a similar event to SN
1997bs. The presence of strong $\mathrm{[N II]}$ lines, near
$\mathrm{H\alpha}$, is suggested as a possible means of identifying objects
such as SN 2002kg/NGC2403-V37 as being LBVs - although not as a general
classification criterion of all LBVs masquerading as SNe (abridged).


title: 74 MHz Discrete HII Absorption Regions Towards The Inner Galaxy

abstract:
  At low radio frequencies (< 100 MHz), classical HII regions may become
optically thick (optical depth > 1) and can be observed as discrete absorption
regions against the Galactic nonthermal background emission created by Galactic
cosmic ray electrons spiraling around magnetic fields. In this work we present
74 MHz observations in the region 26>l>-15, -5<b<5, and report the detection of
92 absorption features associated with known HII regions, and derive the
brightness temperature of the Galactic cosmic ray electron synchrotron emission
emanating from the column behind these regions. For the 42 HII regions with
known distances, the average emissivity of the column behind the HII region is
derived. 74 MHz emissivity values range between 0.3 and 1.0 Kelvin per parsec
for a model assuming uniform distribution of emissivity. Methods for utilizing
this type of data to model the 3-dimensional distribution of cosmic ray
emissivity and the possibility of using this method to break the HII region
kinematic distance degeneracy are discussed.


title:
Clusters at Half Hubble Time: Galaxy Structure and Colors in
  RXJ0152.7-1357 and MS1054-03

abstract:
  We study the photometric and structural properties of spectroscopically
confirmed members in the two massive X-ray--selected z=0.83 galaxy clusters
MS1054-03 and RXJ0152-1357 using three-band mosaic imaging with the Hubble
Space Telescope Advanced Camera for Surveys. The samples include 105 and 140
members of MS1054-03 and RXJ0152-1357, respectively, with ACS F775W magnitude <
24.0. We develop a promising new structural classification method, based on a
combination of the best-fit Sersic indices and the normalized root-mean-square
residuals from the fits; the resulting classes agree well with the visual ones,
but are less affected by galaxy orientation. We examine the color--magnitude
relations in detail and find that the color residuals correlate with the local
mass density measured from our weak lensing maps; we identify a threshold
density of $\Sigma \approx 0.1$, in units of the critical density, above which
the star formation appears to cease. For RXJ0152-1357, we also find a trend in
the color residuals with velocity, resulting from an offset of about 980 km/s
in the mean redshifts of the early- and late-type galaxies. Analysis of the
color--color diagrams indicates that a range of star formation time-scales are
needed to reproduce the loci of the galaxy colors. We also identify some
cluster galaxies whose colors can only be explained by large amounts, $A_V
\approx 1$ mag, of internal dust extinction. [Abstract shortened]


title:
Evolution of the Luminosity-Metallicity-Stellar Mass correlation in a
  hierarchical scenario

abstract:
  We study the evolution of the Stellar Mass-Metallicity Relation and the
Luminosity-Metallicity Relation by performing numerical simulations in a
cosmological framework. We find that the slope and the zero point of the
Luminosity-Metallicity Relation evolve in such a way that, at a given
metallicity, systems were ~3 mag brighter at z=3 compared to galaxies in the
local universe, which is consistent with the observational trend. The local
Stellar Mass-Metallicity Relation shows also a good agreement with recent
observations. We identify a characteristic stellar mass M_c ~ 10^(10.2) M_sun/h
at which the slope of the Stellar Mass-Metallicity Relation decreases for
larger stellar masses. Our results indicate that M_c arises naturally as a
consequence of the hierarchical building up of the structure.


title:
The Shape, Multiplicity, and Evolution of Superclusters in LambdaCDM
  Cosmology

abstract:
  We determine the shape, multiplicity, size, and radial structure of
superclusters in the LambdaCDM concordance cosmology from z = 0 to z = 2.
Superclusters are defined as clusters of clusters in our large-scale
cosmological simulation. We find that superclusters are triaxial in shape; many
have flattened since early times to become nearly two-dimensional structures at
present, with a small fraction of filamentary systems. The size and
multiplicity functions are presented at different redshifts. Supercluster sizes
extend to scales of ~ 100 - 200 Mpc/h. The supercluster multiplicity (richness)
increases linearly with supercluster size. The density profile in superclusters
is approximately isothermal (~ R^{-2}) and steepens on larger scales. These
results can be used as a new test of the current cosmology when compared with
upcoming observations of large-scale surveys.


title: The spatial clustering of ultraluminous infrared galaxies over 1.5<z<3

abstract:
  We present measurements of the spatial clustering of galaxies with stellar
masses >10^11Msun, infrared luminosities >10^12 Lsun, and star formation rates
>200Msun per year in two redshift intervals; 1.5<z<2.0 and 2<z<3. Both samples
cluster very strongly, with spatial correlation lengths of r_0=14.40+/-1.99
h^-1Mpc for the 2<z<3 sample, and r_0=9.40+/-2.24 h^-1Mpc for the 1.5<z<2.0
sample. These clustering amplitudes are consistent with both populations
residing in dark matter haloes with masses of ~6x10^13Msun, making them among
the most biased galaxies at these epochs. We infer, from this and previous
results, that a minimum dark matter halo mass is an important factor for all
forms of luminous, obscured activity in galaxies at z>1, both starbursts and
AGN. Adopting plausible models for the growth of DM haloes with redshift, then
the haloes hosting the 2<z<3 sample will likely host the richest clusters of
galaxies at z=0, whereas the haloes hosting the 1.5<z<2.0 sample will likely
host poor to rich clusters at z=0. We conclude that ULIRGs at z>1 signpost
stellar buildup in galaxies that will reside in clusters at z=0, with ULIRGs at
increasing redshifts signposting the buildup of stars in galaxies that will
reside in increasingly rich clusters.


title: A 22 Degree Tidal Tail for Palomar 5

abstract:
  Using Data Release 4 of the Sloan Digital Sky Survey, we have applied an
optimal contrast, matched filter technique to trace the trailing tidal tail of
the globular cluster Palomar 5 to a distance of 18.5 degrees from the center of
the cluster. This more than doubles the total known length of the tail to some
22 degrees on the sky. Based on a simple model of the Galaxy, we find that the
stream's orientation on the sky is consistent at the 1.7 sigma level with
existing proper motion measurements. We find that a spherical Galactic halo is
adequate to model the stream over its currently known length, and we are able
to place new constraints on the current space motion of the cluster.


title:
Direct Measurements of the Stellar Continua and Balmer/4000 Angstrom
  Breaks of Red z>2 Galaxies: Redshifts and Improved Constraints on Stellar
  Populations

abstract:
  We use near-infrared (NIR) spectroscopy obtained with GNIRS on Gemini,
NIRSPEC on KECK, and ISAAC on the VLT to study the rest-frame optical continua
of three `Distant Red Galaxies' (having Js - Ks > 2.3) at z>2. All three galaxy
spectra show the Balmer/4000 Angstrom break in the rest-frame optical. The
spectra allow us to determine spectroscopic redshifts from the continuum with
an estimated accuracy dz/(1+z) ~ 0.001-0.04. These redshifts agree well with
the emission line redshifts for the 2 galaxies with Halpha emission. This
technique is particularly important for galaxies that are faint in the
rest-frame UV, as they are underrepresented in high redshift samples selected
in optical surveys and are too faint for optical spectroscopy. Furthermore, we
use the break, continuum shape, and equivalent width of Halpha together with
evolutionary synthesis models to constrain the age, star formation timescale,
dust content, stellar mass and star formation rate of the galaxies. Inclusion
of the NIR spectra in the stellar population fits greatly reduces the range of
possible solutions for stellar population properties. We find that the stellar
populations differ greatly among the three galaxies, ranging from a young dusty
starburst with a small break and strong emission lines to an evolved galaxy
with a strong break and no detected line emission. The dusty starburst galaxy
has an age of 0.3 Gyr and a stellar mass of 1*10^11 Msun. The spectra of the
two most evolved galaxies imply ages of 1.3-1.4 Gyr and stellar masses of
4*10^11 Msun. The large range of properties seen in these galaxies strengthens
our previous much more uncertain results from broadband photometry. Larger
samples are required to determine the relative frequency of dusty starbursts
and (nearly) passively evolving galaxies at z~2.5.


title: Cold Dark Matter as Compact Composite Objects

abstract:
  Dark Matter (DM) being the vital ingredient in the cosmos, still remains a
mystery. Standard assumption is that the collisionless cold dark matter (CCDM)
particles are represented by some weakly interacting fundamental fields which
can not be associated with any standard quarks or leptons. However, recent
analyses of structure on galactic and sub-galactic scales have suggested
discrepancies and stimulated numerous alternative proposals including, e.g.
Self-Interacting dark matter, Self-Annihilating dark matter, Decaying dark
matter, to name just a few. We propose the alternative to the standard
assumption about the nature of DM particles (which are typically assumed to be
weakly interacting fundamental point -like particles, yet to be discovered).
Our proposal is based on the idea that DM particles are strongly interacting
composite macroscopically large objects which made of well known light quarks
(or even antiquarks). The required weakness of the DM particle interactions is
guaranteed by a small geometrical factor of the composite objects with a large
baryon charge rather than by a weak coupling constant of a new field. We argue
that the interaction between hadronic matter and composite dark objects does
not spoil the desired properties of the latter as cold matter. We also argue
that such a scenario does not contradict to the current observational data.
Rather, it has natural explanations of many observed data, such as
$\Omega_{DM}/ \Omega_{B}\sim 1$ or $511 KeV$ line from the bulge of our galaxy.
We also suggest that composite dark matter may modify the dynamics of structure
formation in the central overdense regions of galaxies. We also present a
number of other cosmological/astrophysical observations which indirectly
support the novel concept of DM nature.


title: Cosmic Magnetic Fields

abstract:
  Most of the visible matter in the Universe is in a plasma state, or more
specifically is composed of ionized or partially ionized gas permeated by
magnetic fields. Thanks to recent advances on the theory and detection of
cosmic magnetic fields there has been a worldwide growing interest in the study
of their role on the formation of astrophysical sources and the structuring of
the Universe. In this lecture, I will briefly review the importance of the
cosmic magnetic fields both from a theoretical and from an observational
perspective, particularly focusing on stellar and compact objects, the
interstellar medium and star formation regions, and on galaxies, clusters of
galaxies, and the primordial Universe.


title: Chemical Elements at High and Low Redshifts

abstract:
  The past few years have seen a steady progress in the determination of
element abundances at high redshifts, with new and more accurate measures of
metallicities in star-forming galaxies, in QSO absorbers, and in the
intergalactic medium. We have also become more aware of the limitations of the
tools at our disposal in such endeavours. I summarise these recent developments
and--in tune with the theme of this meeting--consider the clues which chemical
abundance studies offer to the links between the high redshift galaxy
populations and today's galaxies. The new data are `fleshing out' the overall
picture of element abundances at redshifts z = 2 - 3 which has been gradually
coming into focus over the last decade. In particular, we can now account for
at least 40% of the metals produced by the global star formation activity in
the universe from the Big Bang to z = 2.5, and we have strong indications of
where the remainder are likely to be found.


title: Basic notions of dense matter physics: applications to astronomy

abstract:
  The aim of this paper is to present basic notions of dense matter physics and
some of its applications to geophysics and astronomy.Topics covered in the
paper include:basic observational data,fun- damental ideas of static high
pressure experiments, notions of theoretical dense matter physics, and finally
some details about theoretical work on dense matter physics and its
astronomical applications in Serbia.


title: Giant Planet Accretion and Migration: Surviving the Type I Regime

abstract:
  In the standard model of gas giant planet formation, a large solid core (~ 10
times the Earth's mass) forms first, then accretes its massive envelope (100 or
more Earth masses) of gas. However, inward planet migration due to
gravitational interaction with the proto-stellar gas disk poses a difficulty in
this model. Core-sized bodies undergo rapid "Type I" migration; for typical
parameters their migration timescale is much shorter than their accretion
timescale. How, then, do growing cores avoid spiraling into the central star
before they ever get the chance to become gas giants? Here, we present a simple
model of core formation in a gas disk which is viscously evolving. As the disk
dissipates, accretion and migration timescales eventually become comparable. If
this happens while there is still enough gas left in the disk to supply a
jovian atmosphere, then a window of opportunity for gas giant formation opens.
We examine under what circumstances this happens, and thus, what predictions
our model makes about the link between proto-stellar disk properties and the
likelihood of forming giant planets.


title: Abundance studies of sdB stars using UV echelle HST/STIS spectroscopy

abstract:
  Aims: We test the hypothesis that the pulsations in sdB stars are correlated
with the surface abundances of iron-group elements. Any correlation might
explain why, when given two spectroscopically similar stars, one will pulsate
while the other will not. Methods: We have obtained high-resolution ultraviolet
spectra two pulsating and three non-pulsating sdB stars using the Space
Telescope Imaging Spectrograph onboard the Hubble Space Telescope. We
determined abundances for 25 elements including the iron group and even heavier
elements such as tin and lead using LTE curve-of-growth and spectrum synthesis
techniques. Results: We find no clear correlation between pulsations and metal
abundances, and we comment on the resulting implications, including whether it
is possible to determine the difference between a pulsating and a non-pulsating
sdB spectroscopically. In addition to the main goal of our observations, we
have also investigated the effect of supersolar metallicity on fundamental
parameter determination, possible trends with iron abundance, and the
hypothesis that weak winds may be selectively removing elements from the
stellar envelopes. These effects provide challenges to stellar atmosphere
modelling and diffusion models for sdB stars.


title:
A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky
  Survey Third Data Release

abstract:
  We present a total of 4784 unique broad absorption line quasars from the
Sloan Digital Sky Survey Third Data Release. An automated algorithm was used to
match a continuum to each quasar and to identify regions of flux at least 10%
below the continuum over a velocity range of at least 1000 km/s in the CIV and
MgII absorption regions. The model continuum was selected as the best-fit match
from a set of template quasar spectra binned in luminosity, emission line
width, and redshift, with the power-law spectral index and amount of dust
reddening as additional free parameters. We characterize our sample through the
traditional ``balnicity'' index and a revised absorption index, as well as
through parameters such as the width, outflow velocity, fractional depth and
number of troughs. From a sample of 16883 quasars at 1.7<z<4.38, we identify
4386 (26.0%) quasars with broad CIV absorption, of which 1756 (10.4%) satisfy
traditional selection criteria. From a sample of 34973 quasars at 0.5<z<2.15,
we identify 457 (1.31%) quasars with broad MgII absorption, 191 (0.55%) of
which satisfy traditional selection criteria. We also provide a supplementary
list of 39 visually identified z>4.38 quasars with broad CIV absorption. We
find that broad absorption line quasars may have broader emission lines on
average than other quasars.


title: Molecular Outflows in Low- and High-Mass Star Forming Regions

abstract:
  We review the known properties of molecular outflows from low- and high-mass
young stars. General trends among outflows are identified, and the most recent
studies on the morphology, kinematics, energetics, and evolution of molecular
outflows are discussed, focusing on results from high-resolution millimeter
observations. We review the existing four broad classes of outflow models and
compare numerical simulations with the observational data. A single class of
models cannot explain the range of morphological and kinematic properties that
are observed, and we propose a possible solution. The impact of outflows on
their cloud is examined, and we review how outflows can disrupt their
surrounding environment, through the clearing of gas and the injection of
momentum and energy onto the gas at distances from their powering sources from
about 0.01 to a few pc. We also discuss the effects of shock-induced chemical
processes on the ambient medium, and how these processes may act as a chemical
clock to date outflows. Lastly, future outflow research with existing and
planned millimeter and submillimeter instruments is presented.


title: Non-equilibrium Ionization State of Warm-Hot Intergalactic Medium

abstract:
  Time evolution of the ionization state of metals in the cosmic baryons is
investigated in a cosmological context without the assumption of ionization
equilibrium. We find that a significant fraction of ionized oxygen ions (OVII
and OVIII) in the warm-hot intergalactic medium (WHIM) is not in the ionization
equilibrium state at a redshift of z~0. We also investigate the effect on the
detectability and observables of WHIM as a consequence of such deviation from
ionization equilibrium. It is found that the detectability of WHIM is not
altered very much both through its emission and absorption signatures, but line
ratios between OVII and OVIII are significantly different from those in the
ionization equilibrium state.


title:
Tip of the Red Giant Branch Distances. I. Optimization of a Maximum
  Likelihood Algorithm

abstract:
  Accurate distances to galaxies can be determined from the luminosities of
stars at the Tip of the Red Giant Branch (TRGB). We use a Maximum Likelihood
algorithm to locate the TRGB in galaxy color-magnitude diagrams. The algorithm
is optimized by introducing reliable photometric errors and a completeness
characterization determined with artificial star experiments. The program is
extensively tested using Monte-Carlo simulations, artificial galaxies, and a
sample of nearby dwarf galaxies observed with HST/WFPC2 and ACS. Our procedure
is shown to be reliable, to have good accuracy, and to not introduce any
systematic errors. The methodology is especially useful in cases where the TRGB
approaches the photometric limit and/or the RGB is poorly populated.


title: Missing Dwarf Problem in Galaxy Clusters

abstract:
  We investigated the formation and evolution of CDM subhalos in galaxy-sized
and cluster-sized halos by means of N-body simulations. Our aim is to make
clear what the ``dwarf galaxy problem'' is. It has been argued that the number
of subhalos in simulated galaxy-sized halos is too large compared to the
observed number of dwarfs in the local group, while that in cluster-sized halos
is consistent with observed number of galaxies in clusters such as the Virgo
cluster. We simulated nine halos with several different mass resolutions and
physical scales. We found that the dependence of the cumulative number of
subhalos N_c on their maximum circular velocity V_c is given by N_c \propto
V_c^-3, down to the reliability limit, independent of the mass of the main
halo. This implies that simulations for cluster-sized halos give too many halos
with V_c ~ 140km/s or less. Previous comparisons of cluster-sized halos gave
much smaller number of subhalos in this regime simply because of their limited
resolution. Our result implies that any theory which attempts to resolve the
missing dwarf problem should also explain the discrepancy of the simulation and
observation in cluster-sized halos.


title:
How Do We See the Relativistic Accretion Disk during Thermal
  Instability?

abstract:
  We calculated the bolometric images of relativistic slim disks during
radiation-pressure-driven thermal instability. When the mass-accretion rate
exceeds the critical one, an inner region of the standard accretion disk bursts
to change to a slim disk state having a large scale height. That is, the inner
region of the disk becomes high temperature, and the thickness of the disk
increases due to the increase of the radiation pressure. As a result, we found
that the observed image of the disk during the burst strongly depends on the
inclination angle. That is, radiation from the innermost disk would be occulted
by the disk outer rim for high inclination angles($i \gtrsim 70^\circ$). We
also calculated the spectral energy distribution during thermal instability.
The Wien peak of the spectrum of high inclination angles becomes softer than
that of low inclination angles due to the geometrical thickness. From these
facts, even if the burst happens in black hole candidates, we may not observe
the burst when the inclination angle is large. We may suggest that numerous
luminous black hole candidates are still hidden in our Galaxy.


title: Performance Limits for Cherenkov Instruments

abstract:
  The performance of Cherenkov instruments for the detection of very high
energy gamma rays is ultimately limited by the fluctuations in the development
of air showers. With particular emphasis on the angular resolution, the
ultimate performance limits are investigated on the basis of simulations.


title: Far-IR Excited OH Lines from Orion KL Outflows

abstract:
  As part of the first far-IR line survey towards Orion KL, we present the
detection of seven new rotationally excited OH Lambda-doublets (at 48, 65, 71,
79, 98 and 115 um). Observations were performed with the Long Wavelength
Spectrometer (LWS) Fabry-Perots on board the Infrared Space Observatory (ISO).
In total, more than 20 resolved OH rotational lines, with upper energy levels
up to 620 K, have been detected at an angular and velocity resolutions of 80$''
and 33 km s^-1 respectively. OH line profiles show a complex behavior evolving
from pure absorption, P-Cygni type to pure emission. We also present a large
scale 6' declination raster in the OH ^2\Pi_3/2 J=5/2^+-3/2^- and ^2\Pi_3/2
J=7/2^-5/2^+ lines (at 119.441 and 84.597 um) revealing the decrease of
excitation outside the core of the cloud. From the observed profiles, mean
intrinsic line widths and velocity offsets between emission and absorption line
peaks we conclude that most of the excited OH arises from Orion outflow(s),
i.e. the ``plateau'' component. We determine an averaged OH abundance relative
to H_2 of X(OH)=(0.5-1.0)x10^-6, a kinetic temperature of 100 K and a density
of n(H_2)=5x10^5 cm^-3. Even with these conditions, the OH excitation is
heavily coupled with the strong dust continuum emission from the inner hot core
regions and from the expanding flow itself.


title: Magneto-convection in a sunspot umbra

abstract:
  Results from a realistic simulation of 3D radiative magneto-convection in a
strong background magnetic field corresponding to the conditions in sunspot
umbrae are shown. The convective energy transport is dominated by narrow upflow
plumes with adjacent downflows, which become almost field-free near the surface
layers. The strong external magnetic field forces the plumes to assume a
cusp-like shape in their top parts, where the upflowing plasma loses its
buoyancy. The resulting bright features in intensity images correspond well (in
terms of brightness, size, and lifetime) to the observed umbral dots in the
central parts of sunspot umbrae. Most of the simulated umbral dots have a
horizontally elongated form with a central dark lane. Above the cusp, most
plumes show narrow upflow jets, which are driven by the pressure of the
piled-up plasma below. The large velocities and low field strengths in the
plumes are effectively screened from spectroscopic observation because the
surfaces of equal optical depth are locally elevated, so that spectral lines
are largely formed above the cusp. Our simulations demonstrate that nearly
field-free upflow plumes and umbral dots are a natural result of convection in
a strong, initially monolithic magnetic field.


title:
Imaging Molecular Gas in the Luminous Merger NGC 3256 : Detection of
  High-Velocity Gas and Twin Gas Peaks in the Double Nucleus

abstract:
  Molecular gas in the merging starburst galaxy NGC 3256 has been imaged with
the Submillimeter Array at a resolution of 1'' x 2'' (170 x 340 pc at 35 Mpc).
This is the first interferometric imaging of molecular gas in the most luminous
galaxy within z=0.01. There is a large disk of molecular gas (r > 3 kpc) in the
center of the merger with a strong gas concentration toward the double nucleus.
The gas disk having a mass of ~3*10^9 Msun in the central 3 kpc rotates around
a point between the two nuclei that are 850 pc apart on the sky. The molecular
gas is warm and turbulent and shows spatial variation of the intensity ratio
between CO isotopomers. High-velocity molecular gas is discovered at the
galactic center. Its velocity in our line of sight is up to 420 km/s offset
from the systemic velocity of the galaxy; the terminal velocity is twice as
large as that due to the rotation of the main gas disk. The high-velocity gas
is most likely due to a molecular outflow from the gas disk, entrained by the
starburst-driven superwind in the galaxy. The molecular outflow is estimated to
have a rate of ~10 Msun/yr and to play a significant role in the dispersal or
depletion of molecular gas from the galactic center. A compact gas
concentration and steep velocity gradient are also found around each of the
twin nuclei. They are suggestive of a small gas disk rotating around each
nucleus. If these are indeed mini-disks, their dynamical masses are ~10^9 Msun
within a radius of 170 pc.


title: Simulated synchrotron emission from Pulsar Wind Nebulae

abstract:
  A complete set of diagnostic tools aimed at producing synthetic synchrotron
emissivity, polarization, and spectral index maps from relativistic MHD
simulations is presented. As a first application we consider here the case of
the emission from Pulsar Wind Nebulae (PWNe). The proposed method is based on
the addition, on top of the basic set of MHD equations, of an extra equation
describing the evolution of the maximum energy of the emitting particles. This
equation takes into account adiabatic and synchrotron losses along streamlines
for the distribution of emitting particles and its formulation is such that it
is easily implemented in any numerical scheme for relativistic MHD. Application
to the axisymmetric simulations of PWNe, analogous to those described by Del
Zanna et al. (2004, A&A, 421, 1063), allows direct comparison between the
numerical results and observations of the inner structure of the Crab Nebula,
and similar objects, in the optical and X-ray bands. We are able to match most
of the observed features typical of PWNe, like the equatorial torus and the
polar jets, with velocities in the correct range, as well as finer emission
details, like arcs, rings and the bright knot, that turn out to arise mainly
from Doppler boosting effects. Spectral properties appear to be well reproduced
too: detailed spectral index maps are produced for the first time and show
softening towards the PWN outer borders, whereas spectral breaks appear in
integrated spectra. The emission details are found to strongly depend on both
the average wind magnetization (here approximately 2%), and on the magnetic
field shape.


title: IGR J11215-5952: a hard X-ray transient displaying recurrent outbursts

abstract:
  The hard X-ray source IGRJ11215-5952 has been discovered with INTEGRAL during
a short outburst in 2005 and proposed as a new member of the class of
supergiant fast X-ray transients. We analysed INTEGRAL public observations of
the source field in order to search for previous outbursts from this transient,
not reported in literature.Our results are based on a systematic re-analysis of
INTEGRAL archival observations, using the latest analysis software and
instrument calibrations. We report the discovery of two previously unnoticed
outbursts, spaced by intervals of ~330 days, that occurred in July 2003 and May
2004. The 5-100keV spectrum is well described by a cut-off power law, with a
photon index of 0.5, and a cut-off energy ~15-20keV, typical of High Mass X-ray
Binaries hosting a neutron star. A 5-100keV luminosity of 3E36 erg/s has been
derived (assuming 6.2kpc, the distance of the likely optical counterpart). The
5-100keV spectral properties, the recurrent nature of the outbursts,together
with the reduced error region containing the blue supergiant star
HD306414,support the hypothesis that IGRJ11215-5952 is a member of the class of
the Supergiant Fast X-ray Transients.


title:
A self-consistent determination of the temperature profile and the
  magnetic field geometry in winds of late-type stars

abstract:
  Cool giant and supergiant stars generally present low velocity winds with
high mass loss rates. Several models have been proposed to explain the
acceleration process of these winds. Although dust is known to be present in
these objects, the radiation pressure on these particles is uneffective in
reproducing the observed physical parameters of the wind. The most promising
acceleration mechanism cited in the literature is the transference of momentum
and energy from Alfven waves to the gas. Usually, these models consider the
wind to be isothermal. We present a stellar wind model in which the Alfven
waves are used as the main acceleration mechanism, and determine the
temperature profile by solving the energy equation taking into account both the
radiative losses and the wave heating. We also determine self-consistently the
magnetic field geometry as the result of the competition between the magnetic
field and the thermal pressures gradient. As main result, we show that the
magnetic geometry present a super-radial index in the region where the gas
pressure is increasing. However, this super-radial index is greater than that
observed for the solar corona.


title: Spectropolarimetry of the Peculiar Type Ia SN 2005hk

abstract:
  We present Keck spectropolarimetry of the unusual type Ia supernova (SN Ia)
2005hk several days before maximum light. An analysis of the high
signal-to-noise-ratio total-flux spectrum shows the object's extreme similarity
to the peculiar SN 2002cx. SN 2005hk has an optical spectrum dominated by Fe
III lines and only weak lines of intermediate-mass elements, unlike a normal SN
Ia at this epoch. The photospheric velocity measured from the minima of strong
absorption lines is very low for an SN Ia (~6000 km s^{-1}), solidifying the
connection to SN 2002cx. The spectrum-synthesis code Synow was used to identify
the presence of iron-peak elements, intermediate-mass elements, and possibly
unburned carbon at similar velocities in the outer ejecta of SN 2005hk. Many
weak spectral features remain unidentified. The spectropolarimetry shows a low
level of continuum polarization (~0.4%) after correction for the interstellar
component and only a weak Fe III line feature is detected. The level of
continuum polarization is normal for an SN Ia, implying that the unusual
features of SN 2005hk cannot be readily explained by large asymmetries.


title: On the similarity of Information Energy to Dark Energy

abstract:
  Information energy is shown here to have properties similar to those of dark
energy. The energy associated with each information bit of the universe is
found to be defined identically to the characteristic energy of a cosmological
constant. Two independent methods are used to estimate the universe information
content of ~10^91 bits, a value that provides an information energy total
comparable to that of the dark energy. Information energy is also found to have
a significantly negative equation of state parameter, w < -0.4, and thus exerts
a negative pressure, similar to dark energy.


title: Metallicity structure in X-ray bright galaxy groups

abstract:
  Using Chandra X-ray data of a sample of 15 X-ray bright galaxy groups, we
present preliminary results of a coherent study of the radial distribution of
metal abundances in the hot gas in groups. The iron content in group outskirts
is found to be lower than in clusters by a factor of ~2, despite showing mean
levels in the central regions comparable to those of clusters. The abundance
profiles are used to constrain the contribution from supernovae type Ia and II
to the chemical enrichment and thermal energy of the intragroup medium at
different group radii. The results suggest a scenario in which a substantial
fraction of the chemical enrichment of groups took place in filaments prior to
group collapse.