title: Stellar Chemical Signatures And Hierarchical Galaxy Formation

abstract:
  ABRIDGED: To compare the chemistries of stars in the Milky Way dSph galaxies
with stars in the Galaxy, we have compiled a large sample of Galactic stellar
abundances from the literature. As found in previous studies, the [alpha/Fe]
ratios of most stars in the dSph galaxies are generally lower than similar
metallicity Galactic stars in this extended sample. Our kinematically selected
stars confirm that this is true for all major stellar components of the Galaxy,
including the halo, thin disk, and thick disk. There is marginal overlap in the
low [alpha/Fe] ratios between dSph stars and Galactic halo stars on extreme
retrograde orbits, but this is not supported by other element ratios, like
[Ba/Y]. Thus, the full chemical signature of most of the dSph stars are
distinct from the main components of the Galaxy. This result rules out
continuous merging of low mass galaxies similar to these dSph satellites during
the formation of the Galaxy, which is discuss further. The new environments
offered by the dSph galaxies also allow us to examine fundamental assumptions
related to nucleosynthesis. The metal-poor stars ([Fe/H] < -1.8) in the dSph
galaxies have [alpha/Fe] ratio that are consistent with predictions from the
alpha-process (alpha-rich freeze out). This may also explain the very low Y
abundances, and could suggest a separate r-process site for this light (first
peak r-process) element. In stars with higher metallicities ([Fe/H] > -1.8),
contributions from the s-process are expected; [Ba/Y] is still much higher in
the dSph stars than similar metallicity Galactic stars though, consistent with
s-process contributions from only the low metallicity AGB stars in dSph
galaxies. Finally, the Na-Ni trend in Galactic halo stars is confirmed, but
discuss this in terms of nucleosynthesis, and not the accretion of dSphs.


title: Conjugate 18cm OH Satellite Lines at a Cosmological Distance

abstract:
  We have detected the two 18cm OH satellite lines from the $z \sim 0.247$
source PKS1413+135, the 1720 MHz line in emission and the 1612 MHz line in
absorption. The 1720 MHz luminosity is $L_{\rm OH} \sim 354 L_\odot$, more than
an order of magnitude larger than that of any other known 1720 MHz maser. The
profiles of the two satellite lines are conjugate, implying that they arise in
the same gas. This allows us to test for any changes in the values of
fundamental constants, without being affected by systematic uncertainties
arising from relative motions between the gas clouds in which the different
lines arise. Our data constrain changes in $G \equiv g_p [\alpha^2/y]^{1.849}$,
where $ y \equiv m_e/m_p$; we find $\Delta G/G = 2.2 \pm 3.8 \times 10^{-5}$,
consistent with no changes in $\alpha$, $g_p$ and $y$.


title:
The Formation of Star Clusters I: 3D Simulations of Hydrodynamic
  Turbulence

abstract:
  We present the results of a series of numerical simulations of compressible,
self-gravitating hydrodynamic turbulence of cluster-forming clumps in molecular
clouds. We examine the role that turbulence has in the formation of
gravitationally bound cores, studying the dynamical state, internal structure
and bulk properties of these cores. Complex structure in turbulent clumps is
formed provided that the damping time of the turbulence, $t_{damp}$ is longer
than the gravitational free-fall time $t_{ff}$ in a region. We find a variety
of density and infall velocity structures among the cores in the simulation,
including cores that resemble the Larson-Penston collapse of an isothermal
sphere ($\rho \propto r^{-2}$) as well as cores that resemble the
McLaughlin-Pudritz collapse of logatropic spheres ($\rho \propto r^{-1}$). The
specific angular momentum profiles range between $j \propto r^{1} - r^{2}$. The
masses of the bound cores that form are well-fit by the turbulent mass spectrum
of Padoan and Nordlund (2002), while the specific angular momentum distribution
can be fit by a broken power law. While our hydrodynamic simulations reproduce
many of the observed properties of cores, we find an upper limit for the star
formation efficiency (SFE) in clusters of 40-50 per cent.


title:
The Northern Sky Optical Cluster Survey IV: An Intermediate Redshift
  Galaxy Cluster Catalog and the Comparison of Two Detection Algorithms

abstract:
  We present an optically selected galaxy cluster catalog from ~ 2,700 square
degrees of the Digitized Second Palomar Observatory Sky Survey (DPOSS),
spanning the redshift range 0.1 < z < 0.5, providing an intermediate redshift
supplement to the previous DPOSS cluster survey. This new catalog contains
9,956 cluster candidates and is the largest resource of rich clusters in this
redshift range to date. The candidates are detected using the best DPOSS plates
based on seeing and limiting magnitude. The search is further restricted to
high galactic latitude (|b| > 50), where stellar contamination is modest and
nearly uniform. We also present a performance comparison of two different
detection methods applied to this data, the Adaptive Kernel and Voronoi
Tessellation techniques. In the regime where both catalogs are expected to be
complete, we find excellent agreement, as well as with the most recent surveys
in the literature. Extensive simulations are performed and applied to the two
different methods, indicating a contamination rate of ~ 5%. These simulations
are also used to optimize the algorithms and evaluate the selection function
for the final cluster catalog. Redshift and richness estimates are also
provided, making possible the selection of subsamples for future studies.


title: Exploring the Universe with the ANTARES neutrino telescope

abstract:
  The ANTARES Collaboration is currently constructing a large neutrino
telescope in the Mediterranean sea. The telescope will use a three-dimensional
array of photomultiplier tubes (PMTs) to detect the Cherenkov light emitted in
sea water by neutrino-induced muons. The array of 12 strings, which hold 900
PMTs, is planned to be deployed at a depth of about 2500 m near Toulon
(France), 40 km off the coast. The scientific objective of ANTARES is to detect
high-energy neutrinos, which may be produced at astrophysical sources -- sites
of the cosmic-ray acceleration, such as quasars, gamma-ray bursters,
microquasars and supernova remnants. The objectives also include the indirect
search for WIMPs by looking for neutrinos from neutralino annihilations in the
centres of the Sun, the Earth and the Galaxy. In 2003 two strings have been
successfully deployed and connected to the electro-optical cable, which
transmitted data to shore station.


title: IceCube: The Cubic Kilometer Neutrino Telescope at the South Pole

abstract:
  Search for ultra high-energy neutrino induced reactions, as part of a
comprehensive probe of the neutrino sky and also investigation of the particle
nature of the dark matter, with unique sensitivity to cold dark matter
particles are described. We present a description of the design, scientific
motivation and goals, performance and status of the IceCube experiment.


title: Dark matter experiments at Boulby mine

abstract:
  The Boulby Dark Matter Collaboration (BDMC) is running several experiments
for particle (WIMP) dark matter search in the Underground Boulby Laboratory.
These include a liquid xenon detector (ZEPLIN I) and a low pressure gas TPC
with directional sensitivity (DRIFT I). Next stage double-phase xenon detectors
ZEPLIN II and ZEPLIN III, and a new TPC DRIFT II will be installed at Boulby in
a few months. Recent results from the running experiments are discussed and
future programme towards large-scale detectors is presented.


title: The Self-Regulated Winds of Long Period Variable Stars

abstract:
  Numerical models of the extended atmospheres of long period variable or Mira
stars have shown that their winds have a very simple, power law structure when
averaged over the pulsation cycle. This structure is stable and robust despite
the pulsational wave disturbances, and appears to be strongly self-regulated.
Observational studies support these conclusions. The models also show that
dust-free winds are nearly adiabatic, with little heating or cooling. The
classical, steady, adiabatic wind solution to the hydrodynamic equations fails
to account for an extensive region of nearly constant outflow velocity. We
investigate analytic solutions which include the effects of wave pressure,
heating, and the resulting entropy changes. Wave pressure is represented by a
term like that in the Reynolds turbulence equation for the mean velocity.
Although the pressure from individual waves is modest, the waves are likely the
primary agent of self-regulation of dust-free winds. In models of dusty winds,
the gas variables also adopt a power law dependence on radius. Heating is
required at all radii to maintain this flow, and grain heating and heat
transfer to the gas are significant. Both hydrodynamic and gas/grain thermal
feedbacks transform the flow towards self-regulated forms. (Abridged)


title: An Inverse Problem Approach to Cluster Dynamics

abstract:
  We propose a new non-parametric algorithm that can be implemented to study
and characterize stellar clusters. The scheme attempts to simultaneously
recover the stellar distribution function and the cluster potential by using
projected radii and velocity information about the cluster members. The pair of
these functions that is most consistent with the input data is detected by the
Metropolis algorithm. In this work, the cluster characteristics recovered by
CHASSIS are calibrated against the N-body realizations of two clusters, namely
Hyades and Arches. The cluster mass and line-of-sight projected velocity
dispersion profiles are correctly reproduced by the algorithm when the cluster
obeys the assumption used in the code, namely isotropy in phase space. The
results recovered by the code are shown to be insensitive to the choice of the
initial parameters. The results are also not influenced by increasing the
number of input data points as long as this number exceeds a minimum value
which is moderately low for an input data set that obeys the assumptions of
isotropy and sphericity.


title: Consistency relation for single scalar inflation

abstract:
  Single scalar field inflation with a generic, non-quadratic in derivatives,
field Lagrangian is considered. It is shown that non-Gaussianity of curvature
perturbations is characterized by two dimensionless amplitudes. One of these
amplitudes can be expressed in terms of the usual inflationary observables --
the scalar power, the tensor power, and the tensor index. This consistency
relation provides an observational test for the single scalar inflation.


title:
NGC 604, the Scaled OB Association (SOBA) Prototype. I: Spatial
  Distribution of the Different Gas Phases and Attenuation by Dust

abstract:
  We have analyzed HST and ground-based data to characterize the different gas
phases and their interaction with the MYC in NGC 604, a GHR in M33. The warm
ionized gas is made out of two components: a high-excitation, high-surface
brightness H II surface located at the faces of the molecular clouds directly
exposed to the ionizing radiation of the central SOBA; and a low-excitation,
low-surface brightness halo that extends to much larger distances from the
ionizing stars. The cavities created by the winds and SN explosions are filled
with X-ray-emitting coronal gas. The nebular lines emitted by the warm gas
experience a variable attenuation as a consequence of the dust distribution,
which is patchy in the plane of the sky and with clouds interspersed among
emission-line sources in the same line of sight. The optical depth at H alpha
as measured from the ratio of the thermal radio continuum to H alpha shows a
very good correlation with the total CO (1-0) column, indicating that most of
the dust resides in the cold molecular phase. The optical depth at H alpha as
measured from the ratio of H alpha to H beta also correlates with the CO
emission but not as strongly as in the previous case. We analyze the difference
between those two measurements and we find that <=11% of the H II gas is hidden
behind large-optical-depth molecular clouds. We detect two candidate compact H
II regions embedded inside the molecular cloud; both are within short distance
of WR/Of stars and one of them is located within 16 pc of a RSG. We estimate
the age of the main stellar generation in NGC 604 to be approx. 3 Myr from the
ionization structure of the H II region. The size of the main cavity is smaller
than the one predicted by extrapolating from single-star wind-blown bubbles.


title: Constraining the Topology of Reionization Through Lyman-alpha Absorption

abstract:
  The reionization of hydrogen in the intergalactic medium (IGM) is a crucial
landmark in the history of the universe, but the processes through which it
occurs remain mysterious. In particular, recent numerical and analytic work
suggest that reionization by stellar sources is driven by large-scale density
fluctuations and must be inhomogeneous on scales of many comoving Mpc. We
examine the prospects for constraining the topology of neutral and ionized gas
through Lyman-alpha absorption of high-redshift sources. One method is to
search for gaps in the Gunn-Peterson absorption troughs of luminous sources.
These could occur if the line of sight passes sufficiently close to the center
of a large HII region. In contrast to previous work, we find a non-negligible
(though still small) probability of observing such a gap before reionization is
complete. In our model the transmission spike at z=6.08 in the spectrum of SDSS
J1148+5251 does not necessarily require overlap to have been completed at an
earlier epoch. We also examine the IGM damping wing absorption of the
Lyman-alpha emission lines of star-forming galaxies. Because most galaxies sit
inside of large HII regions, we find that the severity of absorption is
significantly smaller than previously thought and decoupled from the properties
of the observed galaxy. While this limits our ability to constrain the mean
neutral fraction of the IGM from observations of individual galaxies, it
presents the exciting possibility of measuring the size distribution and
evolution of the ionized bubbles by examining the distribution of damping wing
optical depths in a large sample of galaxies.


title: Hot Gas Structure in the Elliptical Galaxy NGC 4472

abstract:
  We present X-ray spectroscopic and morphological analyses using Chandra ACIS
and ROSAT observations of the giant elliptical galaxy NGC 4472 in the Virgo
cluster. We discuss previously unobserved X-ray structures within the extended
galactic corona. In the inner 2' of the galaxy, we find X-ray holes or cavities
with radii of ~2 kpc, corresponding to the position of radio lobes. These holes
were produced during a period of nuclear activity that began 1.2 x 10^7 years
ago and may be ongoing. We also find an asymmetrical edge in the galaxy X-ray
emission 3' (14 kpc) northeast of the core and an ~8' tail (36 kpc) extending
southwest of the galaxy. These two features probably result from the
interaction of NGC 4472 gas with the Virgo gas, which produces compression in
the direction of NGC 4472's infall and an extended tail from ram pressure
stripping. Assuming the tail is in pressure equilibrium with the surrounding
gas, we compute its angle to our line of sight and estimate that its true
extent exceeds 100 kpc. Finally, in addition to emission from the nucleus
(first detected by Soldatenkov, Vikhlinin & Pavlinsky), we detect two small
extended sources within 10'' of the nucleus of the galaxy, both of which have
luminosities of ~7 x 10^38 erg/s.


title: Soft Gamma Repeaters and Anomalous X-ray Pulsars: Magnetar Candidates

abstract:
  This article is a review of Soft Gamma Repeaters and Anomalous X-ray Pulsars.
It contains a brief historical record of the emergence of these classes of
neutron stars, a thorough overview of the observational data, a succinct
summary of the magnetar model, and suggested directions for future research in
this field.


title: Characterizing Inflationary Perturbations: The Uniform Approximation

abstract:
  The spectrum of primordial fluctuations from inflation can be obtained using
a mathematically controlled, and systematically extendable, uniform
approximation. Closed-form expressions for power spectra and spectral indices
may be found without making explicit slow-roll assumptions. Here we provide
details of our previous calculations, extend the results beyond leading order
in the approximation, and derive general error bounds for power spectra and
spectral indices. Already at next-to-leading order, the errors in calculating
the power spectrum are less than a per cent. This meets the accuracy
requirement for interpreting next-generation CMB observations.


title: Sub-Galactic Clumps at High Redshift: A Fragmentation Origin?

abstract:
  We investigate the origin of the clumpy structures observed at high redshift,
like the chain galaxies. We use a three dimensional chemodynamical simulation
describing the dynamics of stars and a two-phase interstellar medium, as well
as feedback processes from the stars. For high efficiency of energy dissipation
in the cold cloud medium, the initially gaseous disk fragments and develops
several massive clumps of gas and stars. We follow the evolution of the
individual clumps and determine their masses, metallicities and velocities. A
few dynamical times after fragmentation of the disk, the clumps merge to build
a massive bulge. Calculating HST- and UBVRIJHKLM-colors, including absorption
by interstellar dust, we determine the morphologies and colors of this model in
HST images. Several peculiar morphological structures seen in the HDF can be
well-explained by a fragmented galactic disk model, including chain galaxies
and objects consisting of several nearby knots.


title: Simulation of non-Gaussian CMB maps

abstract:
  A simple method is presented for the rapid simulation of
statistically-isotropic non-Gaussian maps of CMB temperature fluctuations with
a given power spectrum and analytically-calculable bispectrum and higher-order
polyspectra. The $n$th-order correlators of the pixel values may also be
calculated analytically. The cumulants of the simulated map may be used to
obtain an expression for the probability density function of the pixel
temperatures. The statistical properties of the simulated map are determined by
the univariate non-Gaussian distribution from which pixel values are drawn
independently in the first stage of the simulation process. We illustrate the
method using a non-Gaussian distribution derived from the wavefunctions of the
harmonic oscillator. The basic simulation method is easily extended to produce
non-Gaussian maps with a given power spectrum and diagonal bispectrum.


title:
Fe II and Mg II in Luminous, Intermediate-Redshift Narrow-line Seyfert 1
  Galaxies from the Sloan Digital Sky Survey

abstract:
  We present results from analysis of spectra from a sample of ~900 quasars
from the Sloan Digital Sky Survey. These objects were selected for their
intermediate redshift (1.2<z<1.8), placing MgII and UV FeII in the optical band
pass, relatively narrow MgII lines, and moderately good signal-to-noise-ratio
spectra. Using a maximum likelihood analysis, we discovered that there is a
significant dispersion in the FeII/MgII ratios in the sample. Using
simulations, we demonstrate that this range, and corresponding correlation
between FeII equivalent width and FeII/MgII ratio, are primarily a consequence
of a larger dispersion of FeII equivalent width (EW) relative to MgII EW. This
larger dispersion in FeII EW could be a consequence of a range in iron
abundance, or in a range of FeII excitation. The latter possibility is
supported by evidence that objects with weak (zero) CII]\lambda 2325 equivalent
width are likely to have large FeII/MgII ratios. We discuss physical effects
that could produce a range of FeII/MgII ratio.


title:
The state of protoplanetary material 10 Myr after stellar formation:
  circumstellar disks in the TW Hydrae association

abstract:
  We have used the Spitzer Infrared Spectrograph to observe seven members of
the TW Hya association, the nearest stellar association whose age ($\sim$ 10
Myr) is similar to the timescales thought to apply to planet formation and disk
dissipation. Only two of the seven targets display infrared excess emission,
indicating that substantial amounts of dust still exist closer to the stars
than is characteristic of debris disks; however, in both objects we confirm an
abrupt short-wavelength edge to the excess, as is seen in disks with
cleared-out central regions. The mid-infrared excesses in the spectra of Hen
3-600 and TW Hya include crystalline silicate emission features, indicating
that the grains have undergone significant thermal processing. We offer a
detailed comparison between the spectra of TW Hya and Hen 3-600, and a model
that corroborates the spectral shape and our previous understanding of the
radial structure of these protoplanetary disks.


title: A Quantum Approach to Dark Matter

abstract:
  This work develops and explores a quantum-based theory which enables the
nature and origin of cold dark matter (CDM) to be understood without need to
introduce exotic particles. The quantum approach predicts the existence of
certain macroscopic quantum structures that are WIMP-like even when occupied by
traditional baryonic particles. These structures function as dark matter
candidates for CDM theory on large scales where it has been most successful,
and retain the potential to yield observationally compliant predictions on
galactic cluster and sub-cluster scales. Relatively pure, high angular
momentum, eigenstate solutions obtained from Schrodinger's equation in weak
gravity form the structural basis. They have no classical analogue, and
properties radically different from those of traditional localised matter
(whose eigenstate spectra contain negligible quantities of such states).
Salient features include radiative lifetimes that can exceed the age of the
universe, energies and 'sizes' consistent with galactic halos, and negligible
interaction rates with radiation and macroscopic galactic objects. This
facilitates the formation of sparsely populated macroscopic quantum structures
that are invisible and stable. Viable structure formation scenarios are based
on the seed potential wells of primordial black holes formed at the e+/e- phase
transition. The structures can potentially produce suitable internal density
distributions and have capacity to accommodate the required amount of halo dark
matter. The formation scenarios show that it is possible to incorporate
structures into universal evolutionary scenarios without significantly
compromising the results of WMAP or the measurements of elemental BBN ratios.


title: A Lyman alpha emitter at z = 6.5 found with slitless spectroscopy

abstract:
  We report the discovery of a Lyman alpha emitting galaxy at z = 6.518. The
single line was found in the 43 square arcmin VLT/FORS field by slitless
spectroscopy limited to the atmospheric window at 9100 A (sampling Lya at 6.4 <
z < 6.6). Its counterpart is undetected in a deep I band image and the line has
an asymmetric appearance in a deeper follow-up spectrum. There are no plausible
line identifications except for Lya with a flux of 1.9x10^-17 erg/s/cm2 and
rest frame equivalent width > 80 A. The lower limit to the star formation rate
density at z = 6.5 derived from our complete sample is 5x10^-4
M_sol/year/Mpc^3, consistent with measurements in the Subaru Deep Field and
Hubble Ultra Deep Field but approximately ten times higher than in the Large
Area Lyman Alpha survey. This Lya emitter is among the very small sample of
highest redshift galaxies known.


title: Emission of CO, CI, and CII in W3Main

abstract:
  We used the KOSMA 3m telescope to map the core 7'x5' of the Galactic massive
star forming region W3Main in the two fine structure lines of atomic carbon and
four mid-J transitions of CO and 13CO. The maps are centered on the luminous
infrared source IRS5 for which we obtained ISO/LWS data comprising four high-J
CO transitions, CII, and OI at 63 and 145 micron. In combination with a KAO map
of integrated line intensities of CII (Howe et al. 1991), this data set allows
to study the physical structure of the molecular cloud interface regions where
the occurence of carbon is believed to change from C+ to C0, and to CO. The
molecular gas in W3Main is warmed by the far ultraviolet (FUV) field created by
more than a dozen OB stars. Detailed modelling shows that most of the observed
line intensity ratios and absolute intensities are consistent with a clumpy
photon dominated region (PDR) of a few hundred unresolved clumps per 0.84pc
beam, filling between 3 and 9% of the volume, with a typical clump radius of
0.025pc (2.2"), and typical mass of 0.44Msun. The high-excitation lines of CO
stem from a 100-200K layer, as also the CI lines. The bulk of the gas mass is
however at lower temperatures.


title: Density-Wave Spiral Theories in the 1960s. I

abstract:
  With the arrival of computers, plasma physics and several fresh investigators
by the early 1960s, understanding the spiral structure of galaxies entered a
new stage of unusually vigorous activity broadly grouped under the umbrella
marked "density-wave theory". Paper I starts with acknowledging B. Lindblad,
rightly regarded the main father of this whole subject, and then describes the
early contributions by Lynden-Bell, Toomre, Hunter and Kalnajs, who had
formulated and applied such notions as the stability of flat galaxies, the
regenerative spiral phenomenon, the shearing density waves and the global
spiral modes. But the foremost enthusiast and proponent of the density-wave
picture was undoubtedly C.C. Lin whose 1964 and 1966 papers with Shu, written
in support of his working hypothesis of the quasi-stationary wave-mode spiral
structure, had a big and immediate impact upon astronomers, at least as a
welcome sign that genuine understanding of the spiral phenomenon seemed in some
sense to be just around the corner.
  We find that even Lin occasionally let himself get carried away with too much
enthusiasm as for instance when he wrote that his relatively exploratory work
with Shu had already led to a "theory free from the kinematical difficulty of
differential rotation", or that it "enables us to provide a mechanism to
explain the existence of a spiral pattern over the whole disk while allowing
the individual spiral arms to be broken and fragmentary" (Lin 1967b, p.462).
Already at the time such optimism was not entirely shared by other experts, and
by the late 1960s - as we shall see in Paper II - it had become very clear to
everyone that much hard work still remained to explain even the persistence,
much less the dynamical origins, of the variety of spirals that we observe.


title: Density-Wave Spiral Theories in the 1960s. II

abstract:
  By the 1970s the spiral subject was in considerable disarray. The
semiempirical theory by Lin and Shu was confronted with serious problems. They
were put on the defensive over their tightly wrapped steady modes on two
principal fronts: from the radial propagation at the group velocity that would
tend to wind them almost at the material rate, and from the tendencies of
galaxy disks toward a strong global instability that appeared likely to
overwhelm them. Of course, one might claim that such threats were imaginary and
only of academic interest, on the ground that nature itself had overcome them.
One might also be confident that the QSSS hypothesis must be correct as
illuminated by the everlasting truth of Hubble's classification. One might even
take pride in the fact that a very promising concept developed, although not
connected to the wave steadiness, on spiral shocks in interstellar gas and
their induced star formation. But such a heuristic approach did not stimulate
very strong progress in understanding dynamical principles of the spiral
phenomenon; moreover, it often misled, and a rich irony was already that the
supposed QSSS favorites M51 and M81 turned out most probably not to be
quasi-steady at all. A further irony was the continuing failure of Lin and Shu
to account the trailing character of their 'modes', while that was already
grasped by their direct 'deductive' opponents. But the greatest irony lay in
the fact that the concept later known as swing amplification, worked out by the
mid-1960s, was originally denigrated by Lin's camp as relating exclusively to
'material arms', whereas it turned out in the end to be of vital importance to
this entire spiral enterprise including the variants of chaotic ragged
patterns, tidal transient grand designs and growing or quasi-steady modes.


title: Polarization and structure of relativistic parsec-scale AGN jets

abstract:
  (Abridged) We consider the polarization properties of optically thin
synchrotron radiation emitted by relativistically moving electron--positron
jets carrying large-scale helical magnetic fields. In our model, the jet is
cylindrical, and the emitting plasma moves parallel to the jet axis with a
characteristic Lorentz factor $\Gamma$. We draw attention to the strong
influence that the bulk relativistic motion of the emitting relativistic
particles has on the observed polarization.
  We conclude that large-scale magnetic fields can explain the salient
polarization properties of parsec-scale AGN jets. Since the typical degrees of
polarization are $\leq 15%$, the emitting parts of the jets must have
comparable rest-frame toroidal and poloidal fields. In this case, most
relativistic jets are strongly dominated by the toroidal magnetic field
component in the observer's frame, $B_\phi/B_z \sim \Gamma$. We also discuss
the possibility that relativistic AGN jets may be electromagnetically (Poynting
flux) dominated. In this case, dissipation of the toroidal magnetic field (and
not fluid shocks) may be responsible for particle acceleration.


title:
Dynamics and Stellar Content of the Giant Southern Stream in M31. I.
  Keck Spectroscopy of Red Giant Stars

abstract:
  We present results from a large spectroscopic survey of M31 red giants using
the Keck telescope/DEIMOS. Photometric pre-screening, based on the 100A-wide
DDO51 band centered on the Mgb/MgH feature, was used to select spectroscopic
targets. Red giant candidates were targeted in a small field on M31's giant
southern tidal stream at a projected distance of 31kpc from the galaxy center.
We isolate a clean sample of 68 giants by removing contaminants (foreground
Galactic dwarfs and background galaxies) using spectroscopic, imaging, and
photometric methods. About 65% of the M31 stars are found to be members of the
stream, while the rest appear to be members of the general halo population. The
mean (heliocentric) radial velocity of the stream in our field is -458 km/s, or
-158 km/s relative to M31's systemic velocity, in good agreement with recent
measurements at other stream locations. The intrinsic velocity dispersion of
the stream is constrained to be 15_{-15}^{+8} km/s (90% confidence limits). The
companion paper by Font et al. (2004, astro-ph/0406146) discusses possible
orbits, implications of the coldness of the stream, and progenitor satellite
properties. The kinematics (and perhaps [Fe/H] distribution) of our halo sample
indicate that it is different from other M31 halo samples; this may be an
indication of substructure in the halo. The stream seems to have a higher mean
[Fe/H] than the halo, -0.51 vs -0.74 dex, and a smaller [Fe/H] spread. The
stream's high metallicity implies that its progenitor must have been a luminous
dwarf galaxy. The CaII triplet strengths of the M31 giants are generally
consistent with photometric estimates of their metallicity (derived by fitting
RGB fiducials in the color-magnitude diagram). There is indirect evidence of
intermediate-age stars in the stream.


title:
Dynamics and Stellar Content of the Giant Southern Stream in M31. II.
  Interpretation

abstract:
  We examine the nature of the progenitor of the giant stellar stream in M31
using as constraints new radial velocity measurements of stream red giant stars
(presented in the companion paper by Guhathakurta et al. 2005,
astro-ph/0406145) along with other M31 data sets available in the literature.
We find that the observations are best fit by orbits that are highly eccentric
and close to edge-on, with apo- to peri-center ratios of order 25 - 30, and
with apocenters at or only slightly beyond the southern edge of the current
data. Among these orbits, we are able to find a few that plausibly connect the
stream with the northern spur or with the low-surface-brightness feature of
similar high metallicity as the stream (originally reported by Ferguson et al.
2002) to the east of M31's center. In the latter case, if the connection is
real, then the eastern debris should lie well in front of M31 near the
apocenter of the orbit. Both the width of the debris and velocity dispersion
measurements imply a rough lower limit on the mass of the progenitor of 10^8
M_sun. We use this limit and our orbits to discuss which of M31's satellites
could be plausibly associated with the stream. In addition, we predict that the
width of the stream should increase beyond the southern edge of the current
data around the apocenter of the orbit and that the line-of-sight velocity
dispersion should exhibit significant variations along the stream.


title:
Molecular line opacity of LiCl in the mid-infrared spectra of brown
  dwarfs

abstract:
  We present a complete line list for the X 1Sigma+ electronic ground state of
LiCl computed using fully quantum-mechanical techniques. This list includes
transition energies and oscillator strengths in the spectral region
0.3-39,640.7 cm-1 for all allowed rovibrational transitions in absorption
within the electronic ground state. The calculations were performed using an
accurate hybrid potential constructed from a spectral inversion fit of
experimental data and from recent multi-reference single- and double-excitation
configuration interaction calculations. The line list was incorporated into the
stellar atmosphere code PHOENIX to compute spectra for a range of young to old
T dwarf models. The possibility of observing a signature of LiCl in absorption
near 15.8 microns is addressed and the proposal to use this feature to estimate
the total lithium elemental abundance for these cool objects is discussed.


title: Identification of luminous infrared galaxies at 1<z<2.5

abstract:
  We present preliminary results on 24micron detections of luminous infrared
galaxies at z>1 with the Multiband Imaging Photometer for Spitzer (MIPS).
Observations were performed in the Lockman Hole and the Extended Groth Strip
(EGS), and were supplemented by data obtained with the Infrared Array Camera
(IRAC) between 3 and 9microns. The positional accuracy of ~2arcsec for most
MIPS/IRAC detections provides unambiguous identifications of their optical
counterparts. Using spectroscopic redshifts from the Deep Extragalactic
Evolutionary Probe survey, we identify 24micron sources at z>1 in the EGS,
while the combination of the MIPS/IRAC observations with $BVRIJHK$ ancillary
data in the Lockman Hole also shows very clear cases of galaxies with
photometric redshifts at 1<z<2.5.
  The observed 24micron fluxes indicate infrared luminosities greater than
10^11 L_sol, while the data at shorter wavelengths reveal rather red and
probably massive (M>=M*) galaxy counterparts. It is the first time that this
population of luminous objects is detected up to z~2.5 in the infrared. Our
work demonstrates the ability of the MIPS instrument to probe the dusty
Universe at very high redshift, and illustrates how the forthcoming Spitzer
deep surveys will offer a unique opportunity to illuminate a dark side of
cosmic history not explored by previous infrared experiments.


title:
Imaging of High Redshift Submillimeter Galaxies at 16 and 22microns with
  the Spitzer/IRS: Revealing a population at z>2.5

abstract:
  We present broad band imaging observations obtained with the ``peak up''
imagers of the Spitzer Space Telescope Infrared Spectrograph (IRS) at
wavelengths of 16micron and 22micron for a number of sources detected primarily
at submillimeter wavelengths, which are believed to be at high, though
undetermined, redshift. We targeted 11 sources originally detected by SCUBA and
5 submillimeter sources detected at 1.2mm by MAMBO. Two optically discovered
quasars with z>6 were also observed to determine if there is detectable dust
emission at such high redshifts. Seven of the submillimeter sources and both
high-redshift quasars were detected, and upper limits of about ~50microJy apply
to the remainder. Using their mid-/far-IR colors, we demonstrate that all of
the submillimeter sources are at z>1.4. The mid-IR colors for two of our
detections and three of our strong upper limits suggest that these galaxies
must be at z>2.5. We also introduce a technique for estimating redshifts and
source characteristics based only on the ratio of fluxes in the 16micron and
22micron images.


title:
The Extraordinary Mid-infrared Spectrum of the Blue Compact Dwarf Galaxy
  SBS0335-052

abstract:
  SBS0335-052 is a blue compact dwarf galaxy (BCD) with one of the lowest known
metallicities, Z$\sim$Z$_{\sun}$/41, making it a local example of how
primordial starburst galaxies and their precursors might appear. A spectrum
obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope
clearly shows silicate absorption features, emission lines of [SIV] and
[NeIII], and puts strong upper limits on the PAH emission features. The
observed low resolution spectrum (R~90) extends from 5.3 to 35microns and peaks
at ~28microns. The spectrum is compared to IRS observations of the prototypical
starburst nucleus NGC7714. SBS0335-052 is quite unlike normal starburst
galaxies, which show strong PAH bands, low ionization emission lines, and a
continuum peak near 80microns. The continuum difference for $\lambda >30 \mu$m
implies a substantial reduction in the mass of cold dust. If the spectrum of
this very low metallicity galaxy is representative of star forming galaxies at
higher redshifts, it may be difficult to distinguish them from AGNs which also
show relatively featureless flat spectra in the mid-IR.


title: Spitzer/IRS Observations of the Redshift 3.91 quasar APM 08279+5255

abstract:
  The Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope (SST) has
been used to obtain low and moderate resolution spectra of the dust and
gas-rich quasar APM08279+5255 (z=3.91). Broad Paschen $\alpha$ and $\beta$
recombination lines of hydrogen were detected at wavelengths of 9.235 and
6.315microns, as well as a strong, red continuum that is a smooth power law
over the observed (rest frame) wavelength range 5.3-35microns (1.08 -
7.1microns). The observed P$\alpha$/P$\beta$ line flux ratio of 1.05$\pm$0.2 is
far from the case B value of ~2 and simple models of high density, high optical
depth ionized gas regions (~1.8). This deviation is opposite in sense to the
expected effect of reddening. No evidence is found in the spectrum for either
the 3.3micron or 6.2micron emission features usually attributed to aromatic
hydrocarbons in gas rich galaxies in the local Universe. This is consistent
with the high luminosity AGN nature of APM08279+5255.


title: Enhancement of Dark Matter Abundance in Scalar-Tensor Dark Energy

abstract:
  In Scalar-Tensor theories of gravity, the expansion rate of the universe in
the past may differ considerably from the standard one. After imposing the
constraints coming from nucleosynthesis, CMB, type Ia supernovae, and solar
system tests of General Relativity, we consider the expansion rate of the
universe at WIMP decoupling, showing that it can lead to an enhancement of the
dark matter relic density of some orders of magnitude with respect to the
standard case. This effect may have a deep impact on most popular candidates
for dark matter, as the supersymmetric neutralino.


title: The nature of luminous X-ray sources with mid-infrared counterparts

abstract:
  We investigate the luminous X-ray sources in the Lockman Hole (LH) and the
Extended Groth Strip (EGS) detected at 24microns using MIPS and also with IRAC
on board Spitzer. We assemble optical/infrared spectral energy distributions
(SEDs) for 45 X-ray/24micron sources in the EGS and LH. Only about 1/4 of the
hard X-ray/24micron sources show pure type 1 AGN SEDs. More than half of the
X-ray/24micron sources have stellar-emission-dominated or obscured SEDs,
similar to those of local type 2 AGN and spiral/starburst galaxies. One-third
of the sources detected in hard X-rays do not have a 24micron counterpart. Two
such sources in the LH have SEDs resembling those of S0/elliptical galaxies.
The broad variety of SEDs in the optical-to-Spitzer bands of X-ray selected AGN
means that AGN selected according to the behavior in the optical/infrared will
have to be supplemented by other kinds of data (e.g., X-ray) to produce
unbiased samples of AGN.


title:
Dust Embedded Sources at the Galactic Center. 2 to 4$\mu$m imaging and
  spectroscopy in the central parsec

abstract:
  We present the first L-band spectroscopic observations for a dozen stellar
sources in the central 0.5 pc of the GC stellar cluster that are bright in the
2-4 micron wavelength domain. With the aid of additional K-band spectroscopic
data, we derive optical depth spectra of the sources after fitting their
continuum emission with a single reddened blackbody continuum. We also derive
intrinsic source spectra by correcting the line of sight extinction via the
optical depth spectrum of a late type star that is most likely not affected by
local dust emission or extinction at the Galactic Center. The good agreement
between the two approaches shows that the overall variation of the
line-of-sight extinction across the central 0.5 pc is $\Delta
A_{\mathrm{K}}\leq0.5$ mag. The extinction corrected spectra of the hot
He-stars are in good agreement with pure Rayleigh Jeans continuum spectra. The
intrinsic spectra of all other sources are in agreement with continuum emission
and absorption features due to the dust in which they are embedded. We
interprete both facts as evidence that a significant amount of the absorption
takes place within the central parsec of the Galactic Center and is most likely
associated with the individual sources there. We find absorption features at
3.0 micron, 3.4 micron, and 3.48 micron wavelength. Correlations between all
three features show that they are very likely to arise in the ISM of the
central 0.5 pc. Spectroscopy of high MIR-excess sources 0.5'' north of the IRS
13 complex is largely consistent with them being YSOs. However, a bow-shock
nature of these sources cannot be excluded.


title:
The ESO Nearby Abell Cluster Survey. XIII. The orbits of the different
  types of galaxies in rich clusters

abstract:
  We study the orbits of the various types of galaxies observed in the ESO
Nearby Abell Cluster Survey. Galaxies within and outside substructures are
considered separately. We use the mass profile we determined from the
distribution and kinematics of the early-type galaxies (i.e. ellipticals,
excluding the brightest ones, and S0s) outside substructures; the latter were
assumed to be on isotropic orbits, which is supported by the shape of their
velocity distribution. The projected distribution and kinematics of the
galaxies of other types are used to search for equilibrium solutions in the
gravitational potential derived from the early-type galaxies, using the method
described by Binney and Mamon as implemented by Solanes and Salvador-Sole'. For
the brightest ellipticals we are not able to construct equilibrium solutions.
This is most likely the result of the formation history and the special
location of these galaxies at the centres of their clusters. The data for the
early spirals allow equilibrium solutions and are consistent with isotropic
orbits, although there is an apparent radial anisotropy at about 0.45 r200. For
the late spirals an equilibrium solution with isotropic orbits is rejected by
the data. The orbits are nearly isotropic within about 0.7 r200, but then
become increasingly radial outwards. Finally, the data for the galaxies in
substructures indicate that isotropic solutions are not acceptable, and
tangential orbits are indicated. We briefly discuss the possible implications
of these velocity-anisotropy profiles for current ideas of the evolution and
transformation of galaxies in clusters. (Abridged)


title: IRAS 04000+5052: A not so compact, not so metal-poor HII region

abstract:
  We present new observations of IRAS 04000+5052, a Galactic HII region
associated with a young stellar cluster and possibly located at the Perseus
arm. Contrary to previous claims, we have found that this object is not a
compact metal-poor HII region. The electron density and chemical composition of
the nebula are similar to those of normal HII regions of the Galactic disk. The
radial velocity of the ionized gas coincides with that obtained from CO
observations, indicating that the nebula is associated with a molecular cloud.
Probably, the ionizing source of the HII region is a Herbig Be star of B0.5
spectral type.


title: Cosmic Star Formation: Constraints on the Galaxy Formation Models

abstract:
  We study the evolution of the cosmic star formation by computing the
luminosity density (LD) in the UV, B, J, and K bands, and the stellar mass
density (MD) of galaxies in two reference models of galaxy evolution: the pure
luminosity evolution (PLE) model developed by Calura & Matteucci (2003) and the
semi-analytical model (SAM) of hierarchical galaxy formation by Menci et al.
(2002). The former includes a detailed description of the chemical evolution of
galaxies of different morphological types with no density evolution; the latter
includes the merging histories of the galactic DM haloes, as predicted by the
hierarchical clustering scenario, but it does not contain morphological
classification nor chemical evolution. We find that at z< 1.5 both models are
consistent with the available data on the LD of galaxies in all the considered
bands. At high z, the LDs predicted in the PLE model show a peak due to the
formation of ellipticals, whereas the SAM predicts a gradual decrease of the
star formation and of the LD for z> 2.5. At such redshifts the PLE predictions
tend to overestimate the present data in the B band whereas the SAM tends to
underestimate the observed UV LD. As for the stellar MD, the PLE picture
predicts that nearly 50% and 85% of the present stellar mass are in place at
z=4 and z=1, respectively. According to the SAM, 50% and 60% of the present
stellar mass are in place at z=1.2 and z=1, respectively. Both predictions fit
the observed MD up to z=1. At z>1, the PLE model and the SAM tend to
overestimate and underestimate the observed values, respectively. We discuss
the origin of the above model results, and the role of observational
uncertainties (such as dust extinction) in comparing models with observations.


title:
Spitzer observations of MAMBO galaxies: weeding out active nuclei in
  starbursting proto-ellipticals

abstract:
  We present Spitzer observations in five wavebands between 3.6 and 24um of an
unbiased sample of 9 luminous, dusty galaxies selected at 1200um by the MAMBO
camera on the IRAM 30-m telescope, a population akin to the well-known submm or
`SCUBA' galaxies (hereafter SMGs). Owing to the coarse resolution of submm/mm
instrumentation, SMGs have traditionally been difficult to identify at other
wavelengths. We compare our multi-wavelength catalogs to show that the overlap
between 24 and 1200um must be close to complete at these flux levels. We find
that all (4/4) of the most secure >=4sigma SMGs have robust >=4sigma
counterparts at 1.4GHz, while the fraction drops to 7/9 using all >=3sigma
SMGs. We show that combining mid-IR and marginal (>=3sigma) radio detections
provides plausible identifications in the remaining cases, enabling us to
identify the complete sample. Accretion onto an obscured central engine is
betrayed by the shape of the mid-IR continuum emission for several sources,
confirming Spitzer's potential to weed out active galaxies. We demonstrate the
power of a S(24um)/S(8um) vs S(8um)/S(4.5um) color-color plot as a diagnostic
for this purpose. However, we conclude that the majority (~75%) of SMGs have
rest-frame mid-/far-IR SEDs commensurate with obscured starbursts. Sensitive
24-um observations are clearly a useful route to identify and characterize
reliable counterparts to high-redshift far-IR-bright galaxies, complementing
what is possible via deep radio imaging.


title: MGGPOD: a Monte Carlo Suite for Gamma-Ray Astronomy

abstract:
  We have developed MGGPOD, a user-friendly suite of Monte Carlo codes built
around the widely used GEANT (Version 3.21) package. The MGGPOD Monte Carlo
suite and documentation are publicly available for download. MGGPOD is an ideal
tool for supporting the various stages of gamma-ray astronomy missions, ranging
from the design, development, and performance prediction through calibration
and response generation to data reduction. In particular, MGGPOD is capable of
simulating ab initio the physical processes relevant for the production of
instrumental backgrounds. These include the build-up and delayed decay of
radioactive isotopes as well as the prompt de-excitation of excited nuclei,
both of which give rise to a plethora of instrumental gamma-ray background
lines in addition to continuum backgrounds.


title:
Observational manifestations of solar magneto-convection --
  center-to-limb variation

abstract:
  We present the first center-to-limb G-band images synthesized from high
resolution simulations of solar magneto-convection. Towards the limb the
simulations show "hilly" granulation with dark bands on the far side, bright
granulation walls and striated faculae, similar to observations. At disk center
G-band bright points are flanked by dark lanes. The increased brightness in
magnetic elements is due to their lower density compared with the surrounding
intergranular medium. One thus sees deeper layers where the temperature is
higher. At a given geometric height, the magnetic elements are cooler than the
surrounding medium. In the G-band, the contrast is further increased by the
destruction of CH in the low density magnetic elements. The optical depth unity
surface is very corrugated. Bright granules have their continuum optical depth
unity 80 km above the mean surface, the magnetic elements 200-300 km below. The
horizontal temperature gradient is especially large next to flux
concentrations. When viewed at an angle, the deep magnetic elements optical
surface is hidden by the granules and the bright points are no longer visible,
except where the "magnetic valleys" are aligned with the line of sight. Towards
the limb, the low density in the strong magnetic elements causes unit
line-of-sight optical depth to occur deeper in the granule walls behind than
for rays not going through magnetic elements and variations in the field
strength produce a striated appearance in the bright granule walls.


title: Colour changes in quasar light curves

abstract:
  The study of quasar variability has long been seen as a way to understanding
the structure of the central engine of active galactic nuclei, and as a means
of verifying the morphology of the standard model. Much work has already been
done on the statistical properties of light curves monitored in one colour, and
it is now possible to use these observations to test predictions of theoretical
models. The addition of a second colour can add enormously to the power of such
tests, and put tight constraints on the nature of the variations. In this paper
a yearly monitoring programme of several hundred quasars in blue and red
passbands covering 21 years is presented. The statistics of colour changes are
examined for a 15 year period of homogeneous data with Fourier power spectrum
analysis, in a form suitable for testing against theoretical predictions. The
results of the Fourier analysis show that there is more power in blue light on
all timescales than in the red. Examination of the light curves shows several
different modes of colour change. However, if allowance is made for the effects
of the underlying host galaxy, the variations become close to achromatie. There
are however structural differences between red and blue light curves which
cannot be accounted for in this way, and various modes of variability including
disc instability and microlensing are examined to provide explanations for
these features.


title:
Possible evidence of surface vibration of strange stars from stellar
  observations

abstract:
  Emission lines in the eV and keV range by certain stellar candidates from
their recent analysis invoke the question of their possible origin. These stars
under consideration, are the 4U 0614+091 (0.65, 0.86, and 1.31 keV), 2S
0918-549 (0.8 keV with width 55 eV), 4U 1543-624 (0.7 keV), 4U 1850-087 (0.7
keV) and 4U 1820-30 (0.6 and 0.9 keV) and also the 0.6 keV excess emission in
RX J170930.2-263927. Recently, it has been suggested that the resonance
absorption at ~ in 0.7, 1.4, 2.1 and 2.8 keV 1E1207-5209 and 0.35, 0.7 and 1.4
keV RX J1856.5-3754 are due to harmonic surface vibrations in strange stars. We
propose that these harmonic vibrations may also responsible for emission lines
in the above mentioned compact stellar candidates.


title: Naked active galactic nuclei

abstract:
  In this paper we report the discovery of a new class of active galactic
nucleus in which although the nucleus is viewed directly, no broad emission
lines are present. The results are based on a survey for AGN in which a sample
of about 800 quasars and emission line galaxies were monitored yearly for 25
years. Among the emission line galaxies was the expected population of Seyfert
2 galaxies with only narrow forbidden lines in emission, and no broad lines.
However, from the long term monitoring programme it was clear that some 10% of
these were strongly variable with strong continuum emission. It is argued that
these objects can only be Seyfert 1 galaxies in which the nucleus is viewed
directly, but in which broad emission lines are completely absent. We compare
these observations with other cases from the literature where the broad line
region is reported to be weak or variable, and investigate the possibility that
the absence of the broad line component is due to reddening. We conclude that
this does not account for the observations, and that in these AGN the broad
line region is absent. We also tentatively identify more luminous quasars from
our sample where the broad emission lines also appear to be absent. The
consequences of this for AGN models are discussed, and a case is made that we
are seeing AGN in a transition stage between the fuel supply from a surrounding
star cluster being cut off, and the nucleus becoming dormant.


title: On the stability of thermonuclear shell sources in stars

abstract:
  We present a quantitative criterion for the thermal stability of
thermonuclear shell sources. We find the thermal stability of shell sources to
depend on exactly three factors: they are more stable when they are
geometrically thicker, less degenerate and hotter. This confirms and unifies
previously obtained results in terms of the geometry, temperature and density
of the shell source, by a simplified but quantitative approach to the physics
of shell nuclear burning. We present instability diagrams in the
temperature-density plane for hydrogen and helium shell burning, which allow a
simple evaluation of the stability conditions of such shell sources in stellar
models. The performance of our stability criterion is demonstrated in various
numerical models: in a 3 Msun AGB star, in helium accreting CO white dwarfs, in
a helium white dwarf which is covered by a thin hydrogen envelope, and in a 1.0
Msun giant.


title:
Effects of rotation on the helium burning shell source in accreting
  white dwarfs

abstract:
  We investigate the effects of rotation on the behavior of the helium burning
shell source in accreting carbon-oxygen white dwarfs, in the context of the
single degenerate Chandrasekhar mass progenitor scenario for Type Ia supernovae
(SNe Ia). We model the evolution of helium accreting white dwarfs of initially
1 Msun, assuming four different constant accretion rates (2, 3, 5 and 10
times10^{-7} Msun/yr). In a one-dimensional approximation, we compute the mass
accretion and subsequent nuclear fusion of helium into carbon and oxygen, as
well as angular momentum accretion, angular momentum transport inside the white
dwarf, and rotationally induced chemical mixing. Our models show two major
effects of rotation: a) The helium burning nuclear shell source in the rotating
models is much more stable than in corresponding non-rotating models -- which
increases the likelihood of accreting white dwarfs to reach the stage of
central carbon ignition. This effect is mainly due to rotationally induced
mixing at the CO/He interface which widens the shell source, and due to the
centrifugal force lowering the density and degeneracy at the shell source
location. b) The C/O-ratio in the layers which experience helium shell burning
-- which may affect the energy of a SN Ia explosion -- is strongly decreased by
the rotationally induced mixing of alpha-particles into the carbon-rich layers.
We discuss implications of our results for the evolution of SNe Ia progenitors.


title: A Review of Bondi--Hoyle--Lyttleton Accretion

abstract:
  If a point mass moves through a uniform gas cloud, at what rate does it
accrete material? This is the question studied by Bondi, Hoyle and Lyttleton.
This paper draws together the work performed in this area since the problem was
first studied. Time has shown that, despite the simplifications made, Bondi,
Hoyle and Lyttleton made quite accurate predictions for the accretion rate.
Bondi--Hoyle--Lyttleton accretion has found application in many fields of
astronomy, and these are also discussed.


title: The Infrared Spectrograph on the Spitzer Space Telescope

abstract:
  The Infrared Spectrograph (IRS) is one of three science instruments on the
Spitzer Space Telescope. The IRS comprises four separate spectrograph modules
covering the wavelength range from 5.3 to 38micron with spectral resolutions, R
\~90 and 600, and it was optimized to take full advantage of the very low
background in the space environment. The IRS is performing at or better than
the pre-launch predictions. An autonomous target acquisition capability enables
the IRS to locate the mid-infrared centroid of a source, providing the
information so that the spacecraft can accurately offset that centroid to a
selected slit. This feature is particularly useful when taking spectra of
sources with poorly known coordinates. An automated data reduction pipeline has
been developed at the Spitzer Science Center.


title: The quantum inflaton, primordial perturbations and CMB fluctuations

abstract:
  We compute the primordial scalar, vector and tensor metric perturbations
arising from quantum field inflation. Quantum field inflation takes into
account the nonperturbative quantum dynamics of the inflaton consistently
coupled to the dynamics of the (classical) cosmological metric. For chaotic
inflation, the quantum treatment avoids the unnatural requirements of an
initial state with all the energy in the zero mode. For new inflation it allows
a consistent treatment of the explosive particle production due to spinodal
instabilities. Quantum field inflation (under conditions that are the quantum
analog of slow roll) leads, upon evolution, to the formation of a condensate
starting a regime of effective classical inflation. We compute the primordial
perturbations taking the dominant quantum effects into account. The results for
the scalar, vector and tensor primordial perturbations are expressed in terms
of the classical inflation results. For a N-component field in a O(N) symmetric
model, adiabatic fluctuations dominate while isocurvature or entropy
fluctuations are negligible. The results agree with the current WMAP
observations and predict corrections to the power spectrum in classical
inflation.Such corrections are estimated to be of the order of m^2/[N H^2]
where m is the inflaton mass and H the Hubble constant at horizon crossing.
This turns to be about 4% for the cosmologically relevant scales. This quantum
field treatment of inflation provides the foundations to the classical
inflation and permits to compute quantum corrections to it.


title:
Kinematics of tidal tails in interacting galaxies: Tidal Dwarf Galaxies
  and projection effects

abstract:
  The kinematics of tidal tails in colliding galaxies has been studied via
Fabry-Perot observations of the Halpha emission. With their large field of view
and high spatial resolution, the Fabry-Perot data allow to probe
simultaneously, in 2-D, two kinematical features of the tidal ionized gas:
large-scale velocity gradients due to streaming motions along the tails, and
small-scale motions related to the internal dynamics of giant HII regions
within the tails. In several interacting systems, massive (10^9 Msun)
condensations of HI, CO and stars are observed in the outer regions of tails.
Whether they are genuine accumulations of matter or not is still debated.
Indeed a part of the tidal tail may be aligned with the line-of-sight, and the
associated projection effect may result in apparent accumulations of matter
that does not exist in the 3-D space. Using numerical simulations, we show that
studying the large-scale kinematics of tails, it is possible to know whether
these accumulations of matter are the result of projection effects or not. We
conclude that several ones are genuine accumulations of matter. We also study
the small-scale motions inside these regions: several small-scale velocity
gradients are identified with projected values as large as 50-100 km/s accross
the observed HII regions. In one system, the spatial resolution of our
observations is sufficient to detail the velocity field; we show that it is
rotating and self-gravitating, and discuss its dark matter content. The
Fabry-Perot observations have thus enabled us to prove that some 10^9 Msun
condensations of matter are real structures, and are kinematically decoupled
from the rest of the tail. Such massive and self-gravitating objects are the
progenitors of the so-called ''Tidal Dwarf Galaxies''.


title: IRS observations of the LMC planetary nebula SMP83

abstract:
  The first observations of the infrared spectrum of the LMC planetary nebula
SMP83 as observed by the recently launched Spitzer Space Telescope are
presented. The high resolution R~600 spectrum shows strong emission lines but
no significant continuum. The infrared fine structure lines are used, together
with published optical spectra, to derive the electron temperature of the
ionized gas for several ions. A correlation between the electron temperature
with ionization potential is found. Ionic abundances for the observed infrared
ions have been derived and the total neon and sulfur abundances have been
determined. These abundances are compared to average LMC abundances of HII
regions to better understand the chemical evolution of these elements. The
nature of the progenitor star is also discussed.


title: Spitzer-IRS Spectroscopy of the Prototypical Starburst Galaxy NGC7714

abstract:
  We present observations of the starburst galaxy NGC 7714 with the Infrared
Spectrograph IRS on board the Spitzer Space Telescope. The spectra yield a
wealth of ionic and molecular features that allow a detailed characterization
of its properties. NGC 7714 has an HII region-like spectrum with strong PAH
emission features. We find no evidence for an obscured active galactic nucleus,
and with [NeIII]/[NeII]~0.73, NGC7714 lies near the upper end of
normal-metallicity starburst galaxies. With very little slicate absorption and
a temperature of the hottest dust component of 340K, NGC 7714 is the perfect
template for a young, unobscured starburst


title:
Spitzer-IRS mapping of the inner kpc of NGC 253: Spatial distribution of
  the Ne III, PAH 11.3 microns and H2 (0-0) S(1) lines and a gradient in the Ne
  III/Ne II line ratio

abstract:
  We present our early results of the mapping of the nucleus of the starburst
galaxy NGC 253 and its immediate surroundings using the Infrared Spectrograph
onboard the Spitzer Space Telescope. The map is centered on the nucleus of the
galaxy and spans the inner 800 x 688 pc2. The spatial distribution of the
\neiii line at 15.55 microns and the polycyclic aromatic hydrocarbons feature
at 11.3 microns peaks at the center while the purely rotationnal transition of
molecular hydrogen at 17.03 microns is strong over several slit positions. We
perform a brief investigation of the implications of these measurement on the
properties of the star formation in this region using theories developped to
explain the deficiency of massive stars in starbursts.


title:
Unified 1-D Simulations of Gamma-Ray Line Emission from Type Ia
  Supernovae

abstract:
  The light curves of Type Ia Supernovae (SN Ia) are powered by gamma-rays
emitted by the decay of radioactive elements such as $^{56}$Ni and its decay
products. These gamma-rays are downscattered,absorbed, and eventually
reprocessed into the optical emission which makes up the bulk of all supernova
observations. Detection of the gamma-rays that escape the expanding star
provide the only direct means to study this power source for SN Ia light
curves. Unfortunately, disagreements between calculations for the gamma-ray
lines have made it difficult to interpret any gamma-ray observations.
  Here we present a detailed comparison of the major gamma-ray line transport
codes for a series of 1-dimensional Ia models. Discrepancies in past results
were due to errors in the codes, and the corrected versions of the seven
different codes yield very similar results. This convergence of the simulation
results allows us to infer more reliable information from the current set of
gamma-ray observations of SNe Ia. The observations of SNe 1986G, 1991T and
1998bu are consistent with explosion models based on their classification:
sub-luminous, super-luminous and normally-luminous respectively.


title:
The Distribution of Dark Matter in the Universe on Scales of 10^10 M_sun
  to 10^15 M_sun

abstract:
  The use of parallel computers and increasingly sophisticated software has
allowed us to perform a large suite of N-body simulations using from $10^8$,to
$10^9$ particles. We will report on our recent convergence tests of the halo
mass function, N-point correlation functions, power spectrum and pairwise
velocity from very large high resolution treecode N-body simulations. Rather
than basing results on just one or two large simulations, now one can
investigate the role of different numerical and physical effects on the
statistics used to characterize the mass distribution of the Universe.


title: Fire and Ice: IRS Mid-IR Spectroscopy of IRAS F00183--7111

abstract:
  We report the detection of strong absorption and weak emission features in
the 4--27 micron Spitzer-IRS spectrum of the distant ultraluminous infrared
galaxy (ULIRG) IRAS F00183--7111 (z=0.327). The absorption features of CO2 and
CO gas, water ice, hydrocarbons and silicates are indicative of a strongly
obscured (A[9.6]>=5.4; A[V]>=90) and complex line of sight through both hot
diffuse ISM and shielded cold molecular clouds towards the nuclear power
source. From the profile of the 4.67 micron CO fundamental vibration mode we
deduce that the absorbing gas is dense (n~10^6 cm^-3) and warm (720 K) and has
a CO column density of ~10^19.5 cm^-2, equivalent to N[H]~10^23.5 cm^-2. The
high temperature and density, as well as the small infered size (<0.03pc),
locates this absorbing gas close to the power source of this region. Weak
emission features of molecular hydrogen, PAHs and Ne+, likely associated with
star formation, are detected against the 9.7 micron silicate feature,
indicating an origin away from the absorbing region. Based on the 11.2 micron
PAH flux, we estimate the star formation component to be responsible for up to
30% of the IR luminosity of the system. While our mid-infrared spectrum shows
no tell-tale signs of AGN activity, the similarities to the mid-infrared
spectra of deeply obscured sources (e.g. NGC4418) and AGN hot dust (e.g.
NGC1068), as well as evidence from other wavelength regions, suggest that the
power source hiding behind the optically thick dust screen may well be a buried
AGN.


title: New views of the solar wind with the Lambert W function

abstract:
  This paper presents closed-form analytic solutions to two illustrative
problems in solar physics that have been considered not solvable in this way
previously. Both the outflow speed and the mass loss rate of the solar wind of
plasma particles ejected by the Sun are derived analytically for certain
illustrative approximations. The calculated radial dependence of the flow speed
applies to both Parker's isothermal solar wind equation and Bondi's equation of
spherical accretion. These problems involve the solution of transcendental
equations containing products of variables and their logarithms. Such equations
appear in many fields of physics and are solvable by use of the Lambert W
function, which is briefly described. This paper is an example of how new
functions can be applied to existing problems.


title: The COBE DIRBE Point Source Catalog

abstract:
  We present the COBE DIRBE Point Source Catalog, an all-sky catalog containing
infrared photometry in 10 bands from 1.25 microns to 240 microns for 11,788 of
the brightest near and mid-infrared point sources in the sky. Since DIRBE had
excellent temporal coverage (100 - 1900 independent measurements per object
during the 10 month cryogenic mission), the Catalog also contains information
about variability at each wavelength, including amplitudes of variation
observed during the mission. Since the DIRBE spatial resolution is relatively
poor (0.7 degrees), we have carefully investigated the question of confusion,
and have flagged sources with infrared-bright companions within the DIRBE beam.
In addition, we filtered the DIRBE light curves for data points affected by
companions outside of the main DIRBE beam but within the `sky' portion of the
scan. At high Galactic latitudes (|b| > 5 degrees), the Catalog contains
essentially all of the unconfused sources with flux densities greater than 90,
60, 60, 50, 90, and 165 Jy at 1.25, 2.2, 3.5, 4.9, 12, and 25 microns,
respectively, corresponding to magnitude limits of approximately 3.1, 2.6, 1.7,
1.3, -1.3, and -3.5. At longer wavelengths and in the Galactic Plane, the
completeness is less certain because of the large DIRBE beam and possible
contributions from extended emission. The Catalog also contains the names of
the sources in other catalogs, their spectral types, variability types, and
whether or not the sources are known OH/IR stars. We discuss a few remarkable
objects in the Catalog. [abridged]


title:
SPI observations of positron annihilation radiation from the 4th
  galactic quadrant: sky distribution

abstract:
  During its first year in orbit the INTEGRAL observatory performed deep
exposures of the Galactic Center region and scanning observations of the
Galactic plane. We report on the status of our analysis of the positron
annihilation radiation from the 4th Galactic quadrant with the spectrometer
SPI, focusing on the sky distribution of the 511 keV line emission. The
analysis methods are described; current constraints and limits on the Galactic
bulge emission and the bulge-to-disk ratio are presented.


title:
Observations of Ultraluminous Infrared Galaxies with the Infrared
  Spectrograph on the Spitzer Space Telescope: Early Results on Mrk 1014, Mrk
  463, and UGC 5101

abstract:
  We present spectra taken with the Infrared Spectrograph on Spitzer covering
the 5-38micron region of three Ultraluminous Infrared Galaxies (ULIRGs): Mrk
1014 (z=0.163), and Mrk 463 (z=0.051), and UGC 5101 (z=0.039). The continua of
UGC 5101 and Mrk 463 show strong silicate absorption suggesting significant
optical depths to the nuclei at 10microns. UGC 5101 also shows the clear
presence of water ice in absorption. PAH emission features are seen in both Mrk
1014 and UGC 5101, including the 16.4micron line in UGC 5101. The fine
structure lines are consistent with dominant AGN power sources in both Mrk 1014
and Mrk 463. In UGC 5101 we detect the [NeV] 14.3micron emission line providing
the first direct evidence for a buried AGN in the mid-infrared. The detection
of the 9.66micron and 17.03micron H$_{2}$ emission lines in both UGC 5101 and
Mrk 463 suggest that the warm molecular gas accounts for 22% and 48% of the
total molecular gas masses in these galaxies.


title:
Waiting in the Wings: Reflected X-ray Emission from the Homunculus
  Nebula

abstract:
  We report the first detection of X-ray emission associated with the
Homunculus Nebula which surrounds the supermassive star Eta Carinae. The
emission is characterized by a temperature in excess of 100 MK, and is
consistent with scattering of the time-delayed X-ray flux associated with the
star. The nebular emission is bright in the northwestern lobe and near the
central regions of the Homunculus, and fainter in the southeastern lobe. We
also report the detection of an unusually broad Fe K fluorescent line, which
may indicate fluorescent scattering off the wind of a companion star or some
other high velocity outflow. The X-ray Homunculus is the nearest member of the
small class of Galactic X-ray reflection nebulae, and the only one in which
both the emitting and reflecting sources are distinguishable.


title: Mergers and Non-Thermal Processes in Clusters of Galaxies

abstract:
  Clusters of galaxies generally form by the gravitational merger of smaller
clusters and groups. Major cluster mergers are the most energetic events in the
Universe since the Big Bang. The basic properties of cluster mergers and their
effects will be discussed. Mergers drive shocks in the intracluster gas, and
these shocks heat the intracluster gas, and should also accelerate nonthermal
relativistic particles. Mergers also produce distinctive features in the X-ray
images of clusters, including "cold fronts" and cool trails. Chandra and
XMM/Newton observations of the X-ray signatures of mergers will be discussed.
X-ray observations of shocks and cold fronts can be used to determine the
geometry and kinematics of the merger. As a result of particle acceleration in
shocks and turbulent acceleration following mergers, clusters of galaxies
should contain very large populations of relativistic electrons and ions.
Observations and models for the radio, extreme ultraviolet, hard X-ray, and
gamma-ray emission from nonthermal particles accelerated in these shocks will
also be described.


title:
Magnetic Effects at the Edge of the Solar System: MHD Instabilities, the
  de Laval nozzle Effect and an Extended Jet

abstract:
  To model the interaction between the solar wind and the interstellar wind,
magnetic fields must be included. Recently Opher et al. 2003 found that, by
including the solar magnetic field in a 3D high resolution simulation using the
University of Michigan BATS-R-US code, a jet-sheet structure forms beyond the
solar wind Termination Shock. Here we present an even higher resolution
three-dimensional case where the jet extends for $150AU$ beyond the Termination
Shock. We discuss the formation of the jet due to a de Laval nozzle effect and
it's su bsequent large period oscillation due to magnetohydrodynamic
instabilities. To verify the source of the instability, we also perform a
simplified two dimensional-geometry magnetohydrodynamic calculation of a plane
fluid jet embedded in a neutral sheet with the profiles taken from our 3D
simulation. We find remarkable agreement with the full three-dimensional
evolution. We compare both simulations and the temporal evolution of the jet
showing that the sinuous mode is the dominant mode that develops into a
velocity-shear-instability with a growth rate of $5 \times 10^{-9}
sec^{-1}=0.027 years^{-1}$. As a result, the outer edge of the heliosphere
presents remarkable dynamics, such as turbulent flows caused by the motion of
the jet. Further study, e.g., including neutrals and the tilt of the solar
rotation from the magnetic axis, is required before we can definitively address
how this outer boundary behaves. Already, however, we can say that the magnetic
field effects are a major player in this region changing our previous notion of
how the solar system ends.


title: PAHs as a tracer of star formation?

abstract:
  IR emission bands at 3.3, 6.2, 7.7, 8.6 and 11.3 um are generally attributed
to IR fluorescence from (mainly) FUV pumped PAHs. As such, they trace the FUV
stellar flux and are a measure of star formation. We examined the IR spectral
characteristics of Galactic star forming regions, normal and starburst
galaxies, AGNs and ULIRGs. The goal is to analyze if PAH bands are a good
qualitative and/or quantitative tracer of star formation and hence the
application of PAH bands as a diagnostic in order to identify the dominant
processes contributing to the IR emission from Seyfert's and ULIRGs. We develop
a MIR/FIR diagnostic and compare it to known diagnostics, with these also
applied to the Galactic sample. This diagnostic is based on the FIR normalized
6.2 um PAH flux and the FIR normalized 6.2 um continuum flux. The Galactic
sources form a sequence spanning a range of 3 orders of magnitude, from
embedded compact HII regions to exposed PDRs and the (D)ISM. The variation in
the 6.2 um PAH/continuum ratio is relative small. Normal and starburst galaxies
ressemble exposed PDRs. While Seyfert-2's coincide with the starburst trend,
Seyfert-1's are displaced by at least a factor 10 in 6.2 um continuum flux.
ULIRGs show a diverse spectral appearance (AGN hot dust continuum,
starburst-like or strong dust obscuration in the nucleus). ULIRGs also seems to
have more prominent FIR emission than either starburst galaxies or AGNs. We
discuss the observed variation in the Galactic sample in view of the
evolutionary state and the PAH/dust abundance and the use of PAHs as
quantitative tracers of star formation activity. We find that PAHs may be
better suited as a tracer of B stars, which dominate the Galactic stellar
energy budget, than as a tracer of massive star formation (O stars).


title: Magnetic Effects Change Our View of the Heliosheath

abstract:
  There is currently a controversy as to whether Voyager 1 has already crossed
the Termination Shock, the first boundary of the Heliosphere. The region
between the Termination Shock and the Heliopause, the Helisheath, is one of the
most unknown regions theoretically. In the Heliosheath magnetic effects are
crucial, as the solar magnetic field is compressed at the Termination Shock by
the slowing flow. Recently, our simulations showed that the Heliosheath
presents remarkable dynamics, with turbulent flows and the presence of a jet
flow at the current sheet that is unstable due to magnetohydrodynamic
instabilities \cite{opher,opher1}. In this paper we review these recent
results, and present an additional simulation with constant neutral atom
background. In this case the jet is still present but with reduced intensity.
Further study, e.g., including neutrals and the tilt of the solar rotation from
the magnetic axis, is required before we can definitively address how the
Heliosheath behaves. Already we can say that this region presents remarkable
dynamics, with turbulent flows, indicating that the Heliosheath might be very
different from what we previously thought.


title:
Rest-Frame MIR Detection of an Extremely Luminous Lyman Break Galaxy
  with the Spitzer IRS

abstract:
  We present the first rest-frame ~4 micron detection of a Lyman break galaxy.
The data were obtained using the 16 micron imaging capability of the Spitzer
Infrared Spectrograph. The target object, J134026.44+634433.2, is an extremely
luminous Lyman break galaxy at z=2.79 first identified in Sloan Digital Sky
Survey spectra (Bentz, Osmer, & Weinberg 2004). The source is strongly detected
with a flux of 0.94 +/- 0.02 mJy. Combining Spitzer and SDSS photometry with
supporting ground-based J- and K-band data, we show that the spectral energy
distribution is consistent with an actively star-forming galaxy. We also detect
other objects in the Spitzer field of view, including a very red MIR source. We
find no evidence of a strong lens amongst the MIR sources.


title: Observing Dark Energy with SNAP

abstract:
  The nature of dark energy is of such fundamental importance -- yet such a
mystery -- that a dedicated dark energy experiment should be as comprehensive
and powerfully incisive as possible. The Supernova/Acceleration Probe robustly
controls for a wide variety of systematic uncertainties, employing the Type Ia
supernova distance method, with high signal to noise light curves and spectra
over the full redshift range from z=0.1-1.7, and the weak gravitational lensing
method with an accurate and stable point spread function.


title: Tilted Ghost Inflation

abstract:
  In a ghost inflationary scenario, we study the observational consequences of
a tilt in the potential of the ghost condensate. We show how the presence of a
tilt tends to make contact between the natural predictions of ghost inflation
and the ones of slow roll inflation. In the case of positive tilt, we are able
to build an inflationary model in which the Hubble constant H is growing with
time. We compute the amplitude and the tilt of the 2-point function, as well as
the 3-point function, for both the cases of positive and negative tilt. We find
that a good fraction of the parameter space of the model is within experimental
reach.


title:
Evidence for a Cosmological Stromgren Surface and for Significant
  Neutral Hydrogen Surrounding the Quasar SDSS J1030+0524

abstract:
  A bright quasar residing in a dense and largely neutral intergalactic medium
(IGM) at high redshifts (z > 6) will be surrounded by a large cosmological
Stromgren sphere. The quasar's spectrum will then show a sharp increase in
resonant Lyman line absorption at wavelengths approaching and shorter than that
corresponding to the Stromgren sphere's boundary along the line of sight. We
show here that simultaneously considering the measured absorption in two or
more hydrogen Lyman lines can provide the dynamical range required to detect
this feature. We model broad and robust features of the Lyman alpha and Lyman
beta regions of the spectrum of the z=6.28 quasar SDSS J1030+0524, using a
hydrodynamical simulation. From the steep wavelength-dependence of the inferred
absorption opacity, we detect the boundary of the Stromgren sphere at a proper
distance of 6.0 +/- 0.2 Mpc away from the source redshift. From the spectrum
alone, we also find that beyond this distance, cosmic hydrogen turns nearly
neutral, with a neutral fraction of x_HI > 0.2, and that the ionizing
luminosity of this quasar is in the range (5.2 +/- 2.5) times 10^{56}
photons/sec. The method presented here, when applied to future quasars, can
probe the complex topology of overlapping ionized regions, and can be used to
study the details of the reionization process.


title: Reconstructing and Deconstructing Dark Energy

abstract:
  The acceleration of the expansion of the universe, ascribed to a dark energy,
is one of the most intriguing discoveries in science. In addition to precise,
systematics controlled data, clear, robust interpretation of the observations
is required to reveal the nature of dark energy. Even for the simplest
question: is the data consistent with the cosmological constant? there are
important subtleties in the reconstruction of the dark energy properties. We
discuss the roles of analysis both in terms of the Hubble expansion rate or
dark energy density \rho_{DE}(z) and in terms of the dark energy equation of
state w(z), arguing that each has its carefully defined place. Fitting the
density is best for learning about the density, but using it to probe the
equation of state can lead to instability and bias.


title: Sunyaev-Zel'dovich Cluster Survey Simulations for Planck

abstract:
  We examine the ability of the future Planck mission to provide a catalogue of
galaxy clusters observed via their SZ distortion in the cosmic microwave
background. For this purpose we produce full-sky SZ maps based on N-body
simulations and scaling relations between cluster properties for several
cosmological models. We extrapolate the N-body simulations by a mass function
to high redshifts in order to obtain a realistic SZ background. The simulated
Planck observations include, besides the thermal and kinematic SZ effects,
contributions from the primordial CMB, extragalactic point sources as well as
Galactic dust, free-free and synchrotron emission. A HSMEM method is used to
separate the SZ signal from contaminating components in combination with a
cluster detection algorithm based on thresholding and flux integration to
identify clusters and to obtain their fluxes. We estimate a survey sensitivity
limit (depending on the quality of the recovered cluster flux) and provide
cluster survey completeness and purity estimates. We find that given our
modelling and detection algorithm Planck will reliably detect at least several
thousands of clusters over the full sky. The exact number depends on the
particular cosmological model (up to 10000 cluster detections in a concordance
LCDM model with sigma_8=0.9). We show that the Galaxy does not significantly
affect the cluster detection. Furthermore, the dependence of the thermal SZ
power spectrum on the matter variance on scales of 8 Mpc/h and the quality of
its reconstruction by the employed method are investigated. Our simulations
suggest that the Planck cluster sample will not only be useful as a basis for
follow-up observations, but also will have the ability to provide constraints
on cosmological parameters.


title:
Photometry of SN 2002ic and Implications for the Progenitor Mass-Loss
  History

abstract:
  We present new pre-maximum and late-time optical photometry of the Type
Ia/IIn supernova 2002ic. These observations are combined with the published
V-band magnitudes of Hamuy et al. (2003) and the VLT spectrophotometry of Wang
et al. (2004) to construct the most extensive light curve to date of this
unusual supernova. The observed flux at late time is significantly higher
relative to the flux at maximum than that of any other observed Type Ia
supernova and continues to fade very slowly a year after explosion. Our
analysis of the light curve suggests that a non-Type Ia supernova component
becomes prominent $\sim20$ days after explosion. Modeling of the non-Type Ia
supernova component as heating from the shock interaction of the supernova
ejecta with pre-existing circumstellar material suggests the presence of a
$\sim1.7 10^{15}$ cm gap or trough between the progenitor system and the
surrounding circumstellar material. This gap could be due to significantly
lower mass-loss $\sim15 (v_w/10 km/s)^{-1}$ years prior to explosion or
evacuation of the circumstellar material by a low-density fast wind. The latter
is consistent with observed properties of proto-planetary nebulae and with
models of white-dwarf + asymptotic giant branch star progenitor systems with
the asymptotic giant branch star in the proto-planetary nebula phase.


title: Far Infrared Imaging of NGC 55

abstract:
  We present images of the galaxy NGC 55 at 24, 70, and 160 micron obtained
with the Multiband Imaging Photometer for Spitzer (MIPS) instrument aboard the
Spitzer Space Telescope. The new images display the far infrared emission in
unprecedented detail and demonstrate that the infrared morphology differs
dramatically from that at shorter wavelengths. The most luminous emission
region in the galaxy is marginally resolved at 24 micron and has a projected
separation of nearly 520 pc from the peak emission in the optical and near
infrared. This region is responsible for ~9% of the total emission at 24 micron
and is likely a young star formation region. We show that this and other
compact sources account for more than 1/3 of the total 24 micron emission. We
compute a total infrared luminosity for NGC 55 of 1.2*10^9 L_sun. The star
formation rate implied by our measurements is 0.22 M_sun/yr. We demonstrate
that the cold dust is more extended than the warm dust in NGC 55--the
minor-axis scale heights are 0.32, 0.43, and 0.49 kpc at 24, 70 and 160 micron,
respectively. The dust temperature map shows a range of temperatures that are
well-correlated with the 24 micron surface brightness, from 20 K in
low-surface-brightness regions to 26 K in high-surface-brightness regions.


title: Outstanding Questions about Mergers in Clusters of Galaxies

abstract:
  At the request of the organizers of the Santa Fe meeting on X-Ray and Radio
Connections, I list some important questions and lines of inquiry for the
future study of the X-ray and radio connections in mergers in clusters of
galaxies, These questions are based on the talks, posters, and discussions at
this meeting,


title: On the nature of dark matter

abstract:
  Dark matter in the universe seems to be one of the most important puzzles
science has to face in this moment. In this essay we point out that dark matter
could be a spin-0 fundamental interaction of Nature rather than a simple
particle. From this hypothesis follows that dark matter behaves just as
standard cold dark matter at cosmological level while still in good agreement
with observations at galactic scales. This new interaction could be one of the
scalar fields predicted by higher-dimensional theories.


title: The Cosmic Microwave Background and Inflation Parameters

abstract:
  We review the currrent cosmic parameter determinations of relevance to
inflation using the WMAP-1year, Boomerang, CBI, Acbar and other CMB data. The
basic steps in the pipelines which determine the bandpowers from the raw data
from which these estimations are made are summarized. We forecast how the
precision is likely to improve with more years of WMAP in combination with
future ground-based experiments and with Planck. We address whether the current
data indicates strong breaking from uniform acceleration through the relatively
small region of the inflaton potential that the CMB probes, manifest in the
much-discussed running spectral index or in even more radical braking/breaking
scenarios. Although some weak ``anomalies'' appear in the current data, the
statistical case is not there. However increased precision, at the high
multipole end and with polarization measurements, will significantly curtail
current freedom.


title: Lick Northern Proper Motion Program. III. Lick NPM2 Catalog

abstract:
  The Lick Northern Proper Motion (NPM) program, a two-epoch (1947-1988)
photographic survey of the northern two-thirds of the sky (Dec. > -23 deg), has
measured absolute proper motions, on an inertial system defined by distant
galaxies, for 380,000 stars from 8 <B < 18. The 1993 NPM1 Catalog contains
148,940 stars in 899 fields outside the Milky Way's zone of avoidance. The 2003
NPM2 Catalog contains 232,062 stars in the remaining 347 NPM fields near the
plane of the Milky Way. This paper describes the NPM2 star selection, plate
measurements, astrometric and photometric data reductions, and catalog
compilation. The NPM2 Catalog contains 120,000 faint (B > 14) anonymous stars
for astrometry and galactic studies, 92,000 bright (B < 14) positional
reference stars, and 35,000 special stars chosen for astrophysical interest.
The NPM2 proper motions are on the ICRS system, via Tycho-2 stars, to an
accuracy of 0.5 mas/yr in each field. RMS proper motion precision is 6 mas/yr.
Positional errors average 80 mas at the mean plate epoch 1968, and 200 mas at
the NPM2 catalog epoch 2000. NPM2 photographic photometry errors average 0.18
mag in B, and 0.20 mag in B-V. The NPM2 Catalog and the updated (to J2000) NPM1
Catalog are available at the CDS Strasbourg data center and on the NPM WWW site
(http://www.ucolick.org/~npm). The NPM2 Catalog completes the Lick Northern
Proper Motion program after a half-century of work by three generations of Lick
Observatory astronomers. The NPM Catalogs will serve as a database for research
in galactic structure, stellar kinematics, and astrometry.


title:
AST/RO Observations of CO J=4-3 Emission from the N44 Complex in the
  Large Magellanic Cloud

abstract:
  We present Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)
observations of 12CO J=4-3 and C I emission in the N44 H II complex in the
Large Magellanic Cloud. We detected strong 12CO J=4-3 emission toward the H II
region called as N44BC, which is located on the rim of an expanding giant shell
in the N44 region. Analysis with a photodissociation region (PDR) model showed
that the 12CO J=4-3 emitting cloud is very dense, with n ~ 10^5 cm^-3. We also
note that there is a high-velocity component associated with the 12CO J=4-3
emission. This probably originates from molecular material accelerated as a
result of the motion induced by the expanding giant shell surrounding LH47 in
the N44 complex. We found that the kinetic energy of this high-velocity gas
observed in the CO J=4-3 emission toward the rim of the expanding H II shell is
at least an order of magnitude higher than the kinetic energy derived for the H
I and H II gas in this region.


title: OH Maser Observations of Planetary Nebulae Precursors

abstract:
  We present OH maser observations at 1612, 1665, 1667, and 1720 MHz for 86
post-asymptotic giant branch (post-AGB) stars selected from a survey of 1612
MHz maser sources in the Galactic Plane. The observations were taken with the
Parkes Telescope and the Australia Telescope Compact Array between 2002
September and 2003 August. Post-AGB stars are the precursors to planetary
nebulae, the diverse morphological range of which is unexplained. The maser
observations were taken to investigate the onset and incidence of wind
asymmetries during the post-AGB phase. We re-detected all 86 sources at 1612
MHz while 27 sources were detected at 1665 and 45 at 1667 MHz. One source was
re-detected at 1720 MHz. We present a classification scheme for the maser
profiles and show that 25% of sources in our sample are likely to have
asymmetric or bipolar outflows. From a comparison of the maser and far-infrared
properties we find that there is a likely trend in the shape of the maser
profiles with some sources evolving from double-peaked to irregular to fully
bipolar profiles. A subset of higher-mass sources stand out as having almost no
mainline emission and mostly double-peaked profiles. At least 25% of sources in
the sample are variable at one or more of the frequencies observed. We also
confirm a previously-noted 1667 MHz overshoot phenomenon.


title:
X-ray/UV campaign on the Mrk 279 outflow: density diagnostics in Active
  Galactic Nuclei using O V K-shell absorption lines

abstract:
  One of the main problems in modeling the ionised outflows in Active Galactic
Nuclei is the unknown distance of the outflowing wind to the central source.
Only if the density is known this distance can be determined through the
ionisation parameter. Here we study density diagnostics based upon O V
transitions. O V is known to have metastable levels that are density dependent.
We study the population of those levels under photoionisation equilibrium
conditions and determine for which parameter range they can have a significant
population. We find that resonance line trapping plays an important role in
reducing the critical densities above which the metastable population becomes
important. We investigate the K-shell absorption lines from these metastable
levels. Provided that there is a sufficient population of the metastable
levels, the corresponding K-shell absorption lines are detectable and are well
separated from the main absorption line originating from the ground state. We
then present the Chandra LETGS spectrum of the Seyfert 1 galaxy Mrk 279 that
may show for the first time the presence of these metastable level absorption
lines. A firm identification is not yet possible due to both uncertainties in
the observed wavelength of the strongest line as well as uncertainties in the
predicted wavelength. If the line is indeed due to absorption from O V, then we
deduce a distance to the central source of one light week to a few light
months, depending upon the importance of additional heating processes.


title:
X-ray/UV Campaign on the Mrk 279 AGN Outflow: Constraining Inhomogeneous
  Absorber Models

abstract:
  We investigate the applicability of inhomogeneous absorber models in the
formation of AGN outflow absorption-troughs. The models we explore are limited
to monotonic gradients of absorbing column densities in front of a finite
emission source. Our main finding is that simple power-law and gaussian
distributions are hard pressed to fit the Mrk 279 high-quality UV outflow data.
An acceptable fit for the O VI troughs can only be obtained by assuming
unrealistic optical depth values (upward of 100). The strongest constraints
arise from the attempt to fit the Lyman series troughs. In this case it is
evident that even allowing for complete freedom of both the power-law exponent
and the optical depth as a function of velocity cannot yield an acceptable fit.
In contrast, partial covering models do yield good fits for the Lyman series
troughs. We conclude that monotonic inhomogeneous absorber models that do not
include a sharp edge in the optical depth distribution across the source are
not an adequate physical model to explain the trough formation mechanism for
the outflow observed in Mrk 279.