title: Dark Matter and Dark Energy: The Critical Questions

abstract:
  Stars account for only about 0.5% of the content of the Universe; the bulk of
the Universe is optically dark. The dark side of the Universe is comprised of:
at least 0.1% light neutrinos; 3.5% +/- 1% baryons; 29% +/- 4% cold dark
matter; and 66% +/- 6% dark energy. Now that we have characterized the dark
side of the Universe, the challenge is to understand it. The critical questions
are: (1) What form do the dark baryons take? (2) What is (are) the
constituent(s) of the cold dark matter? (3) What is the nature of the
mysterious dark energy that is causing the Universe to speed up.


title: Star Formation in the Hubble Deep Field North

abstract:
  I am currently analyzing the emission line spectra of the approximately 600
galaxies from the sample of Cohen et al. (2000) and Cohen (2001) in the region
of the HDF-North with z<1.5. A progress report on this effort of the Caltech
Faint Galaxy Redshift Survey is presented.


title:
The Clumpiness of Cold Dark Matter: Implications for the Annihilation
  Signal

abstract:
  We examine the expected signal from annihilation events in realistic cold
dark matter halos. If the WIMP is a neutralino, with an annihilation
cross-section predicted in minimal SUSY models for the lightest stable relic
particle, the central cusps and dense substructure seen in simulated halos may
produce a substantial flux of energetic gamma rays. We derive expressions for
the relative flux from such events in simple halos with various density
profiles, and use these to calculate the relative flux produced within a large
volume as a function of redshift. This flux peaks when the first halos
collapse, but then declines as small halos merge into larger systems of lower
density. Simulations show that halos contain a substantial amount of dense
substructure, left over from the incomplete disruption of smaller halos as they
merge together. We calculate the contribution to the flux due to this
substructure, and show that it can increase the annihilation signal
substantially. Overall, the present-day flux from annihilation events may be an
order of magnitude larger than predicted by previous calculations. We discuss
the implications of these results for current and future gamma-ray experiments.


title: Massive Stars and The Creation of our Galactic Center

abstract:
  Our Galactic Center hosts over 10% of the known massive stars in the Galaxy.
The majority of these stars are located in three particularly massive clusters
that formed within the past 5 Myr. While these clusters are extraordinary,
their formation repesents about half of the total inferred star formation rate
in the Galactic Center. There is mounting evidence that the clusters are just
present-day examples of the hundreds of such similar clusters that must have
been created in the past, and whose stars now comprise the bulk of all stars
seen in the region. I discuss the massive stellar content in the Galactic
Center and present a new analysis that suggests that effects of continuous star
formation in the Galactic Center can be seen in the observed luminosity
functions newly-obtained HST/NICMOS and Gemini AO data.


title:
Extreme Ultraviolet Absorption Lines in LyA Forest Absorbers and the
  Oxygen Abundance in the Intergalactic Medium

abstract:
  We create stacked composite absorption spectra from Hubble Space Telescope
Faint Object Spectrograph data from four quasi-stellar objects to search for
absorption lines in the extreme ultraviolet wavelength region associated with
LyA forest absorbers in the redshift range 1.6 < z < 2.9. We successfully
detect O V 630 in LyA absorbers throughout the 10^13 to 10^16.2 cm^-2 column
density range. For a sample of absorbers with 10^13.2 < N(H I) < 10^14.2 cm^-2,
corresponding to gas densities ranging from around the universal mean to
overdensities of a few, we measure an O V 630 equivalent width of 10.9 +/- 3.7
mA. We estimate the detection is real with at least 99% confidence. We only
detect O IV 788, O IV 554, O III 833, and HeI 584 in absorbers with LyA
equivalent widths > 0.6 A, which are likely associated with traditional
metal-line systems. We find no evidence in any subsamples for absorption from N
IV 765, NeV 568, NeVI 559, NeVIII 770, 780, or MgX 610, 625. The measured
equivalent widths of O V suggest values of <O V / H I> in the range -1.7 to
-0.6 for 10^13.2 < N(H I) < 10^15 cm^-2. The lack of detectable O IV absorption
except in the strongest absorption systems suggests a hard ionizing background
similar to the standard Haardt & Madau spectrum. Using photoionization models,
we estimate that the oxygen abundance in the intergalactic medium with respect
to the solar value is [O / H] around -2.2 to -1.3. Comparing to studies of C
IV, we estimate [O / C] around 0.3 to 1.2. The overabundance of oxygen relative
to carbon agrees with other low-metallicity abundance measurements and suggests
enrichment of the intergalactic medium by Type II supernovae.


title: The 2000 Periastron Passage of PSR B1259-63

abstract:
  We report here on a sequence of 28 observations of the binary pulsar system
PSR B1259-63/SS2883 at four radio frequencies made with the Australia Telescope
Compact Array around the time of the 2000 periastron passage. Observations made
on 2000 Sep 1 show that the pulsar's apparent rotation measure (RM) reached a
maximum of $-14800 \pm 1800$ rad m$^{-2}$, some 700 times the value measured
away from periastron, and is the largest astrophysical RM measured. This value,
combined with the dispersion measure implies a magnetic field in the Be star's
wind of 6 mG. We find that the light curve of the unpulsed emission is similar
to that obtained during the 1997 periastron but that differences in detail
imply that the emission disc of the Be star is thicker and/or of higher
density. The behaviour of the light curve at late times is best modelled by the
adiabatic expansion of a synchrotron bubble formed in the pulsar/disc
interaction. The expansion rate of the bubble $\sim 12$ km s$^{-1}$ is
surprisingly low but the derived magnetic field of 1.6 G close to that
expected.


title:
A New High-Redshift Lyman alpha Emitter: Possible Superwind Galaxy at z
  = 5.69

abstract:
  During the course of our deep optical imaging survey for Ly alpha emitters at
z approximately 5.7 in the field around the z=5.74 quasar SDSSp
J104433.04-012502.2, we have found a candidate strong emission-line source.
Follow-up optical spectroscopy shows that the emission line profile of this
object is asymmetric, showing excess red-wing emission. These properties are
consistent with an identification of Ly alpha emission at a redshift of z=5.687
+/- 0.002. The observed broad line width, Delta V_{FWHM} ~= 340 km s^{-1} and
excess red-wing emission also suggest that this object hosts a galactic
superwind.


title:
A Study of 3CR Radio Galaxies from z = 0.15 to 0.65. II. Evidence for an
  Evolving Radio Structure

abstract:
  Radio structure parameters were measured from the highest quality radio maps
available for a sample of 3CR radio galaxies in the redshift range 0.15 < z <
0.65. Combined with similar data for quasars in the same redshift range, these
morphology data are used in conjunction with a quantification of the richness
of the cluster environment around these objects (the amplitude of the
galaxy-galaxy spatial covariance function, Bgg) to search for indirect evidence
of a dense intracluster medium (ICM). This is done by searching for confinement
and distortions of the radio structure that are correlated with Bgg.
Correlations between physical size and hot spot placement with Bgg show
evidence for an ICM only at z < 0.4 and there are no correlations at z > 0.4,
suggesting an epoch of z ~ 0.4 for the formation of an ICM in these Abell
richness class 0-1, FR2-selected clusters. X-ray selected clusters at
comparable redshifts, which contain FR1 type sources exclusively, are
demonstrably richer than the FR2-selected clusters found in this study. The
majority of the radio sources with high Bgg values at z < 0.4 can be described
as ``fat doubles'' or intermediate FR2/FR1s. The lack of correlation between
Bgg and bending angle or Bgg and lobe length asymmetry suggests that these
types of radio source distortion are caused by something other than interaction
with a dense ICM. Thus, a large bending angle cannot be used as an unambiguous
indicator of a rich cluster around powerful radio sources. These results
support the hypothesis made in Paper 1 that cluster quasars fade to become
FR2s, then FR1s, on a timescale of 0.9 Gyrs (for H0 = 50 km s^-1 Mpc^-1).


title:
The Accretion Rates and Spectral Energy Distributions of BL Lacertae
  Objects

abstract:
  We investigate the relationship between accretion rates and the spectral
energy distributions (SEDs) of BL Lac objects, using a sample of objects for
which published information on the host galaxies, emission-line luminosities,
and peak frequencies and luminosities of their SEDs are available. The sample
is composed of 43 BL Lac objects which have a relatively continuous
distribution of peak frequencies. Under the assumption that the observed
emission lines are photoionized by the central accretion disk, we use the line
luminosities to estimate the accretion luminosities and hence accretion rates.
We find that low frequency-peaked BL Lac objects (LBLs) span a wide range of
accretion rates, whereas high frequency-peaked BL Lac objects (HBLs) cover a
more restricted range of lower values. There appears to be a continuous
distribution of accretion rates between the two subclasses of BL Lac objects.
We find that the peak frequency of the SED, $\pknu$, correlates with the
accretion rate, approximately with the form $\pknu\propto \Lambda^{-3}$ in HBLs
and $\pknu \propto \Lambda^{-0.25}$ in LBLs, where $\Lambda \equiv L_{\rm
lines}/c^2$. The peak luminosity of the SED is also correlated with $\Lambda$.
These results suggest that the accretion rate influences the shape of the SED
in BL Lac objects. They also support models which couple the jet and the
accretion disk. We present a physical scenario to account for the empirical
trends.


title:
A Trustworthy and Simple Method to Determine Pulsar Distances and the
  Electron Distribution in the Galaxy

abstract:
  We present the model for determination of pulsar distances or average
electron distribution using a method similar to the widely used dependence of
A$_V$ on distances in different directions. To have reliable pulsar distances,
we have used several natural requirements and distances of pulsar-calibrators.
We have constructed dispersion measure-distance relations for pulsars in 48
different directions.


title:
HST/STIS Observations of the Bipolar Jet from RW Aurigae: Tracing
  Outflow Asymmetries Close to the Source

abstract:
  We have observed the bipolar jet from RW Aur A with STIS on board the HST.
After continuum subtraction, morphological and kinematic properties of this
outflow can be traced to within 0."1 from the source in forbidden emission
lines. The jet appears well collimated, with typical FWHMs of 20 to 30 AU in
the first 2" and surprisingly does not show a separate low-velocity component
in contrast to earlier observations. The systemic radial outflow velocity of
the blueshifted lobe is typically 50% larger than that of the redshifted one
with a velocity difference of about 65 km/s. Although such asymmetries have
been seen before on larger scales, our high spatial resolution observations
suggest that they are intrinsic to the "central engine" rather than effects of
the star's immediate environment. Temporal variations of the bipolar jet's
outflow velocities appear to occur on timescales of a few years. They have
combined to produce a 55% increase in the velocity asymmetry between the two
lobes over the past decade. In the red lobe estimated mass flux and momentum
flux values are around one half and one third of those for the blue lobe,
respectively. The mass outflow to mass accretion rate is 0.05, the former being
measured at a distance of 0."35 from the source.


title: Experimental Particle Dark Matter Search

abstract:
  Several aspects of the motivation for particle dark matter search are
introduced. The experimental principles and present state of the most important
experiments are presented. Direct searches for WIMPs are explained in some
detail, indirect WIPM searches and axion searches are presented more briefly.


title: Mass-loss predictions and stellar masses of early-type stars

abstract:
  We show that the stellar masses implied by our predictions of the wind
properties of massive stars are in agreement with masses derived from evolution
theory and from direct measurements using spectroscopic binaries, contrary to
previous attempts to derive masses from wind theory.


title: The winds of Luminous Blue Variables and the Mass of AG Car

abstract:
  We present radiation-driven wind models for Luminous Blue Variables (LBVs)
and predict their mass-loss rates. A comparison between our predictions and the
observations of AG Car shows that the variable mass loss behaviour of LBVs is
due the recombination/ionisation of Fe IV/III and Fe III/II. We also derive a
present-day mass of 35 Msun for AG Car.


title:
Numerical Simulation of Non-Gaussian Random Fields with Prescribed
  Marginal Distributions and Cross-Correlation Structure II: Multivariate
  Random Fields

abstract:
  We provide theoretical procedures and practical recipes to simulate
non-Gaussian correlated, homogeneous random fields with prescribed marginal
distributions and cross-correlation structure, either in a N-dimensional
Cartesian space or on the celestial sphere. We illustrate our methods using
far-infrared maps obtained with the Infrared Space Observatory. However, the
methodology presented here can be used in other astrophysical applications that
require modeling correlated features in sky maps, for example, the simulation
of multifrequency sky maps where backgrounds, sources and noise are correlated
and can be modeled by random fields.


title:
Power spectrum of the cosmic infrared background at 60 and 100 microns
  with IRAS

abstract:
  Based on a power spectrum analysis of the IRAS ISSA maps, we present the
first detection of the Cosmic far-Infrared Background (CIB) fluctuations at 60
and 100 microns. The power spectrum of 12 low cirrus emission regions is
characterized by a power excess at spatial frequencies higher than k~0.02
arcmin^{-1}. Most of this excess is due to noise and to nearby point sources
with a flux stronger than 1 Jy. But we show that when these contributions are
carefully removed, there is still a power excess that is the signature of the
CIB fluctuations. The power spectrum of the CIB at 60 and 100 microns is
compatible with a Poissonian distribution, at spatial frequencies between 0.025
and 0.2 arcmin^{-1}. The fluctuation level is ~1.6x10^3 Jy^2/sr and ~5.8x10^3
Jy^2/sr at 60 and 100 microns respectively. The levels of the fluctuations are
used in a larger framework, with other observationnal data, to constrain the
evolution of IR galaxies (Lagache et al. 2002). The detections reported here,
coupled with the level of the fluctuations at 170 microns, give strong
constraints on the evolution of the IR luminosity function. The combined
results at 60, 100 and 170 microns for the CIB and its fluctuations allows, on
the CIB at 60 microns, to put a firm upper limit of 0.27 MJy/sr and to give an
estimate of 0.18 MJy/sr.


title: Widespread HCO emission in the M82's nuclear starburst

abstract:
  We present a high-resolution (~ 5'') image of the nucleus of M82 showing the
presence of widespread emission of the formyl radical (HCO). The HCO map, the
first obtained in an external galaxy, reveals the existence of a structured
disk of ~ 650 pc full diameter. The HCO distribution in the plane mimics the
ring morphology displayed by other molecular/ionized gas tracers in M82. More
precisely, rings traced by HCO, CO and HII regions are nested, with the HCO
ring lying in the outer edge of the molecular torus. Observations of HCO in
galactic clouds indicate that the abundance of HCO is strongly enhanced in the
interfaces between the ionized and molecular gas. The surprisingly high overall
abundance of HCO measured in M82 (X(HCO) ~ 4x10^{-10}) indicates that its
nuclear disk can be viewed as a giant Photon Dominated Region (PDR) of ~ 650 pc
size. The existence of various nested gas rings, with the highest HCO abundance
occurring at the outer ring (X(HCO) ~ 0.8x10^{-9}), suggests that PDR chemistry
is propagating in the disk. We discuss the inferred large abundances of HCO in
M82 in the context of a starburst evolutionary scenario, picturing the M82
nucleus as an evolved starburst.


title:
The blue compact dwarf galaxy I Zw 18: a comparative study of its
  low-surface-brightness component

abstract:
  (abridged): Using HST and ground-based optical and NIR imaging data, we
investigate whether the blue compact dwarf (BCD) galaxy I Zw 18 possesses an
extended low-surface-brightness (LSB) old stellar population underlying its
star-forming (SF) regions. We show that the exponential intensity decrease
observed in the filamentary LSB envelope of the BCD out to 18 arcsec (1.3 kpc
at a distance of 15 Mpc) is not due to an evolved stellar disc, but rather due
to extended ionized gas emission. Broad-band images reveal, after subtraction
of nebular line emission, a compact stellar LSB component extending slightly
beyond the SF regions. This stellar host, being blue over a radius range of 5
exponential scale lengths and showing little colour contrast to the SF
component, differs strikingly from the red LSB host of standard BCDs. This
fact, in connection with the blue colors of component I Zw 18 C, suggests that
most of the stellar mass in I Zw 18 has formed within the last 0.5 Gyr.
Furthermore, we show that the exponential intensity fall-off in the filamentary
ionized envelope of I Zw 18 is not particular to this system but a common
property of the ionized halo of many SF dwarf galaxies on galactocentric
distances of several kpc. In the absence of an appreciable underlying stellar
background, extended ionized gas emission dominates in the periphery of I Zw
18, mimicking an exponential stellar disc on optical surface brightness
profiles.


title:
The mass profile of A1413 observed with XMM-Newton: implications for the
  M-T relation

abstract:
  We present an XMM-Newton observation of A1413, a hot (kT = 6.5 keV) galaxy
cluster at z=0.143. We construct gas and temperature profiles up to ~1700 kpc,
equivalent to ~0.7 r_200. The gas distribution is well described by a beta
model in the outer regions, but is more concentrated in the inner ~250 kpc. We
introduce a new parameterisation for the inner regions, allowing a steeper gas
density distribution. The projected radial temperature profile declines
gradually towards the outer regions, by ~20% between 0.1 r_200 and 0.5 r_200,
and is well described by a polytropic model with gamma = 1.07+/-0.01. We find
that neither projection nor PSF effects change substantially the form of the
temperature profile. Assuming hydrostatic equilibrium (HE) and spherical
symmetry, we use the observed temperature profile and the new parametric form
for the gas density profile to produce the total mass distribution. The mass
profile is remarkably well fitted with the Moore et al. (1999) parameterisation
with a concentration parameter in the range expected from numerical
simulations. There are several indications that beyond a density contrast delta
\~600, the gas may no longer be in HE. There is an offset with respect to
adiabatic numerical simulations in the virialised part of the cluster, in that
the predicted mass for the cluster temperature is ~40% too high. The gas
distribution is peaked in the centre primarily as a result of the cusp in the
dark matter profile. The X-ray gas to total mass ratio rises with increasing
radius to f_gas ~ 0.2. These data strongly support the validity of the current
approach for the modelling of the dark matter collapse, but confirm that
understanding the gas specific physics is essential. (Abridged)


title: Rummaging through Earth's attic for remains of ancient life

abstract:
  We explore the likelihood that early remains of Earth, Mars, and Venus have
been preserved on the Moon in high enough concentrations to motivate a search
mission. During the Late Heavy Bombardment, the inner planets experienced
frequent large impacts. Material ejected by these impacts near the escape
velocity would have had the potential to land and be preserved on the surface
of the Moon. Such ejecta could yield information on the geochemical and
biological state of early Earth, Mars and Venus. In order to determine whether
the Moon has preserved enough ejecta to justify a search mission, we calculate
the amount of Terran material incident on the Moon over its history by
considering the distribution of ejecta launched from the Earth by large
impacts. In addition, we make analogous estimates for Mars and Venus. We find,
for a well mixed regolith, that the median surface abundance of Terran material
is roughly 7 ppm, corresponding to a mass of approximately 20,000 kg of Terran
material over a 10 x 10 square km area. Over the same area, the amount of
material transferred from Venus is 1-30 kg, and material from Mars as much as
180 kg. Given that the amount of Terran material is substantial, we estimate
the fraction of this material surviving impact with intact geochemical and
biological tracers.


title: The Redshift of a Lensing Galaxy in PMN J0134-0931

abstract:
  The Sloan Digital Sky Survey (SDSS) automatically targeted as a quasar
candidate the recently discovered, gravitationally lensed, extremely reddened
z=2.2 quasar PMN J0134-0931. The SDSS spectrum exhibits Ca II absorption at
z=0.76451, which we identify as the redshift of a lensing galaxy. Hubble Space
Telescope imaging shows that components CDE of the system are significantly
redder than components A or B and detects faint galaxy emission between D and
A+B. The redshift of the dust responsible for the reddening remains
unconstrained with current data. However, we outline a model wherein lensing
and differential reddening by a z=0.76451 galaxy pair can entirely explain this
system. Detecting mm-wave molecular line absorption from the lensing galaxy or
galaxies may be possible in PMN J0134-0931, just as in the lenses PKS1830-211
and B0218+357. Well-constructed optical quasar surveys like the SDSS can
contribute to the detection and study of reddened quasars. (Expanded)


title: MODEST-1: Integrating Stellar Evolution and Stellar Dynamics

abstract:
  We summarize the main results from MODEST-1, the first workshop on MOdeling
DEnse STellar systems. Our goal is to go beyond traditional population
synthesis models, by introducing dynamical interactions between single stars,
binaries, and multiple systems. The challenge is to define and develop a
software framework to enable us to combine in one simulation existing computer
codes in stellar evolution, stellar dynamics, and stellar hydrodynamics. With
this objective, the workshop brought together experts in these three fields, as
well as other interested astrophysicists and computer scientists. We report
here our main conclusions, questions and suggestions for further steps toward
integrating stellar evolution and stellar (hydro)dynamics.


title: Neutrino trapping and accretion models for Gamma-Ray Bursts

abstract:
  Many models of Gamma Ray Bursts invoke a central engine consisting of a black
hole of a few solar masses accreting matter from a disk at a rate of a fraction
to a few solar masses per second. Popham et al. and Narayan et al. have shown
that, for Mdot >~ 0.1 Msun/s, accretion proceeds via neutrino cooling and
neutrinos can carry away a significant amount of energy from the inner regions
of the disks. We improve on these calculations by including a simple
prescription for neutrino transfer and neutrino opacities in such regions. We
find that the flows become optically thick to neutrinos inside a radius
R~6-40R_s for Mdot in the range of 0.1 -10 Msun/s, where R_s is the black hole
Schwarzchild radius. Most of the neutrino emission comes from outside this
region and, the neutrino luminosity stays roughly constant at a value L_{\nu} ~
10^{53} erg/s. We show that, for Mdot > 1 Msun/s, neutrinos are sufficiently
trapped that energy advection becomes the dominant cooling mechanism in the
flow. These results imply that neutrino annihilation in hyperaccreting black
holes is an inefficient mechanism for liberating large amounts of energy.
Extraction of rotational energy by magnetic processes remains the most viable
mechanism.


title:
The Faint Optical Afterglow and Host Galaxy of GRB 020124: Implications
  for the Nature of Dark Gamma-Ray Bursts

abstract:
  We present ground-based optical observations of GRB 020124 starting 1.6 hours
after the burst, as well as subsequent Very Large Array (VLA) and Hubble Space
Telescope (HST) observations. The optical afterglow of GRB 020124 is one of the
faintest afterglows detected to date, and it exhibits a relatively rapid decay,
$F_\nu\propto t^{-1.60\pm 0.04}$, followed by further steepening. In addition,
a weak radio source was found coincident with the optical afterglow. The HST
observations reveal that a positionally coincident host galaxy must be the
faintest host to date, R>29.5 mag. The afterglow observations can be explained
by several models requiring little or no extinction within the host galaxy,
A_V~0-0.9 mag. These observations have significant implications for the
statistics of the so-called dark bursts (bursts for which no optical afterglow
is detected), which are usually attributed to dust extinction within the host
galaxy. The faintness and relatively rapid decay of the afterglow of GRB
020124, combined with the low inferred extinction indicate that some dark
bursts are intrinsically dim and not dust obscured. Thus, the diversity in the
underlying properties of optical afterglows must be observationally determined
before substantive inferences can be drawn from the statistics of dark bursts.


title:
The X-ray evolving universe: (ionized) absorption and dust, from nearby
  Seyfert galaxies to high-redshift quasars

abstract:
  (Abridged) Cold and warm absorbers have beeen detected in all types of active
galaxies (AGN) from low to high redshift. This gas, located in the black hole
region of AGN, is thought to play an important role in AGN unification
scenarios, in explaining the X-ray background, in black hole growth and AGN
evolution.
  We provide a review of the observations of dusty and dust-free warm and cold
absorbers at low and high redshift, including most recent results and exciting
questions still open. Emphasis is on the science issues that we will be able to
address with XEUS for the first time, particularly at high redshift, including:
(i) determination of metal abundances of X-ray (cold) absorbers by detection of
metal absorption edges, (ii) analysis of the composition of dust mixed with
cold and ionized gas (K-edges of metals in cold dust and cold gas will be
resolvable from each other for the first time), (iii) measurement of the
velocity field of the gas, (iv) utilization of these results to investigate the
evolution of gas and dust in AGN from high to low redshift: the evolution of
abundances, dust content, ionization state, amount and velocity of gas, and its
role in feeding the black hole.
  We emphasize the importance of iron absorption measurements with XEUS at high
redshift for two key issues of cosmology: the early star formation history of
the universe, and the measurement of cosmological parameters. As an example, we
discuss recent XMM-Newton observations of the high-redshift BAL quasar APM
08279+5255.


title:
The Physical Conditions for Massive Star Formation: Dust Continuum Maps
  and Modeling

abstract:
  Fifty-one dense cores associated with water masers were mapped at 350 micron.
These cores are very luminous, 10^3 < Lbol/Lsun < 10^6, indicative of the
formation of massive stars. Dust continuum contour maps and photometry are
presented for these sources. The spectral energy distributions and normalized
radial profiles of dust continuum emission were modeled for 31 sources using a
one-dimensional dust radiative transfer code, assuming a power law density
distribution in the envelope, n = n_f (r/r_f)^{-p}. The best fit density power
law exponent, p, ranged from 0.75 to 2.5 with <p> = 1.8 +/- 0.4. The mean value
of p is comparable to that found in regions forming only low mass stars. The
mean p is incompatible with a logatropic sphere (p = 1), but other star
formation models cannot be ruled out. Different mass estimates are compared and
mean masses of gas and dust are reported within a half-power radius determined
from the dust emission and within a radius where the total density exceeds 10^4
cm^3. Evolutionary indicators commonly used for low mass star formation may
have some utility for regions forming massive stars. For comparison with
extragalactic star formation studies, the luminosity to dust mass ratio is
calculated for these sources with a method most parallel to that used in
studies of distant galaxies and is found to be similar to that seen in high
redshift starburst galaxies.


title: Atomic data for the K-vacancy states of Fe XXIV

abstract:
  As part of a project to compute improved atomic data for the spectral
modeling of iron K lines, we report extensive calculations and comparisons of
atomic data for K-vacancy states in Fe XXIV. The data sets include: (i) energy
levels, line wavelengths, radiative and Auger rates; (ii) inner-shell electron
impact excitation rates and (iii) fine structure inner-shell photoionization
cross sections. The calculations of energy levels and radiative and Auger rates
have involved a detailed study of orbital representations, core relaxation,
configuration interaction, relativistic corrections, cancellation effects and
semi-empirical corrections. It is shown that a formal treatment of the Breit
interaction is essential to render the important magnetic correlations that
take part in the decay pathways of this ion. As a result, the accuracy of the
present A-values is firmly ranked at better than 10% while that of the Auger
rates at only 15%. The calculations of collisional excitation and
photoionization cross sections take into account the effects of radiation and
spectator Auger dampings. In the former, these effects cause significant
attenuation of resonances leading to a good agreement with a simpler method
where resonances are excluded. In the latter, resonances converging to the K
threshold display symmetric profiles of constant width that causes edge
smearing.


title: On the Structure of the Iron K-Edge

abstract:
  It is shown that the commonly held view of a sharp Fe K edge must be modified
if the decay pathways of the series of resonances converging to the K
thresholds are adequately taken into account. These resonances display damped
Lorentzian profiles of nearly constant widths that are smeared to impose
continuity across the threshold. By modeling the effects of K damping on
opacities, it is found that the broadening of the K edge grows with the
ionization level of the plasma and that the appearance at high ionization of a
localized absorption feature at 7.2 keV is identified as the K-beta unresolved
transition array.


title:
Magnetic Fields of Accreting X-Ray Pulsars with the Rossi X-Ray Timing
  Explorer

abstract:
  Using a consistent set of models, we parameterized the X-ray spectra of all
accreting pulsars in the Rossi X-ray Timing Explorer database which exhibit
Cyclotron Resonance Scattering Features (CRSFs, or cyclotron lines). These
sources in our sample are Her X-1, 4U 0115+63, Cen X-3, 4U 1626-67, XTE
J1946-274, Vela X-1, 4U 1907+09, 4U 1538-52, GX 301-2, and 4U 0352+309 (X Per).
We searched for correlations among the spectral parameters, concentrating on
how the cyclotron line energy relates to the continuum and therefore how the
neutron star B-field influences the X-Ray emission. As expected, we found a
correlation between the CRSF energy and the spectral cutoff energy. However,
with our consistent set of fits we found that the relationship is more complex
than what has been reported previously. Also, we found that not only does the
width of the cyclotron line correlate with the energy (as suggested by theory),
but that the width scaled by the energy correlates with the depth of the
feature. We discuss the implications of these results, including the
possibility that accretion directly affects the relative alignment of the
neutron star spin and dipole axes. Lastly, we comment on the current state of
fitting phenomenological models to spectra in the RXTE/BeppoSAX era and the
need for better theoretical models of the X-Ray continua of accreting pulsars.


title: STIS UV spectroscopy of early B supergiants in M31

abstract:
  We analyze STIS spectra in the 1150-1700 Angstrom wavelength range obtained
for six early B supergiants in the neighboring galaxy M31. Because of their
likely high (nearly solar) abundance, these stars were originally chosen to be
directly comparable to their Galactic counterparts, and represent a much-needed
addition to our current sample of B-type supergiants, in our efforts to study
the dependence of the Wind Momentum-Luminosity Relationship on spectral type
and metallicity. As a first step to determine wind momenta we fit the P-Cygni
profiles of the resonance lines of N V, Si IV and C IV with standard methods,
and derive terminal velocities for all of the STIS targets. From these lines we
also derive ionic stellar wind column densities. Our results are compared with
those obtained previously in Galactic supergiants, and confirm earlier claims
of `normal' wind line intensities and terminal velocities in M31. For half of
the sample we find evidence for an enhanced maximum turbulent velocity when
compared to Galactic counterparts.


title:
Formation of an evanescent proto-neutron star binary and the origin of
  pulsar kicks

abstract:
  If core collapse leads to the formation of a rapidly rotating bar-unstable
proto-neutron star surrounded by fall-back material, then we might expect it to
cool and fragment to form a double (proto)-neutron star binary into a
super-close orbit. The lighter star should survive for awhile, until tidal mass
loss propels it toward the minimum stable mass of a (proto)-neutron star,
whereupon it explodes. Imshennik and Popov have shown that the explosion of the
unstable, cold star can result in a large recoil velocity of the remaining
neutron star. Here, we consider several factors that mitigate the effect and
broaden the range of final recoil speeds, in particular the finite velocity and
gravitational deflection of the ejecta, a range of original masses for the low
mass companion and its cooling history, rotational phase averaging of the
momentum impulse from non-instantaneous mass loss, and the possibility of a
common envelope phase. In spite of these mitigating factors, we argue that this
mechanism can still lead to substantial neutron star recoil speeds, close to,
or even above, 1000 km/s.


title: The stability of MHD Taylor-Couette flow

abstract:
  The linear marginal instability of an MHD Taylor-Couette flow of infinite
vertical extension is considered. For hydrodynamically unstable flows the
minimum Reynolds number exists even without a magnetic field, but there are
also solutions with smaller Reynolds numbers for certain (weak) magnetic
fields. The magnetic field can, therefore, destabilize the rotating flow. This
instability, however, can only exist for not too small magnetic Prandtl
numbers. Also the situation for nonaxisymmetric disturbances is considered.
Without magnetic fields such modes possess higher Reynolds numbers than the
axisymmetric modes. The situation is changed in the MHD regime. For modest
magnetic fields the excitation of modes with m=1 is easier than the excitation
of modes with m=0 if critical magnetic amplitudes are exceeded.


title: Axisymmetrical Gas Inflow in the Central Region of NGC 7331

abstract:
  New Integral Field Spectroscopy of the central region of NGC 7331 reveals
strong H$\alpha$ emission in the well-known CO and HI ring of NGC 7331. The
[NII]/H$\alpha$ ratio indicates that a large scale stellar formation process is
taken place at the ring in agreement with previous hypothesis about the
exhaustion of gas in the inner to the ring region. The dynamics of stars and
gas are not coupled. There is a ring of peculiar velocities in the ionized gas
velocity map. These peculiar velocities can be well interpreted by the presence
of an axisymmetric inflow of 40 km/s at the inner boundary of the large-scale
gaseous ring. We infer an inwards total flux of 1.6 M$_{\odot}$yr$^{-1}$. This
value is typical of the accretion rates in hypothetical {\bf large} nuclear
black holes. Despite the large differences in the scales of the nucleus and the
gas ring of NGC 7331, we suggest that this inwards flux is feeding the nucleus.


title: Angular momentum transport in the solar supergranulation layer

abstract:
  The eddy viscosity in the solar supergranulation layer is derived from the
observed rotational shear by computing theoretical rotation laws for the
outermost parts of the solar convection zone using the results from numerical
simulations of rotating convection as input. By varying the eddy viscosity, the
results can be tuned to match the observations. The value of 1.5 X 10^13 cm^2/s
found for the eddy viscosity is considerably larger than the eddy magnetic
diffusivity derived from the sunspot decay. The results are checked by
comparison of the horizontal cross correlations of the velocity fluctuations
with the observed Ward profile.


title:
Nonaxisymmetric patterns in the linear theory of MHD Taylor-Couette
  instability

abstract:
  The linear stability of MHD Taylor-Couette flow of infinite vertical
extension is considered for various magnetic Prandtl numbers Pm. The
calculations are performed for a wide gap container with \hat\eta=0.5 with an
axial uniform magnetic field excluding counterrotating cylinders. For both
hydrodynamically stable and unstable flows the magnetorotational instability
produces characteristic minima of the Reynolds number for certain (low)
magnetic field amplitudes and Pm> 0.01. For Pm <~ 1 there is a characteristic
magnetic field amplitude beyond which the instability sets in in form of
nonaxisymmetric spirals with the azimuthal number m=1. Obviously, the magnetic
field is able to excite nonaxisymmetric configurations despite of the tendency
of differential rotation to favor axisymmetric magnetic fields which is known
from the dynamo theory. If Pm is too big or too small, however, the
axisymmetric mode with m=0 appears to be the most unstable one possessing the
lowest Reynolds numbers -- as it is also true for hydrodynamic Taylor-Couette
flow or for very weak fields. That the most unstable mode for modest Pm proves
to be nonaxisymmetric must be considered as a strong indication for the
possibility of dynamo processes in connection with the magnetorotational
instability.


title: Future supernovae data and quintessence models

abstract:
  The possibility to unambiguously determine the equation-of-state of the
cosmic dark energy with existing and future supernovae data is investigated. We
consider four evolution laws for this equation-of-state corresponding to four
quintessential models, i.e. i) a cosmological constant, ii) a general
barotropic fluid, iii) a perfect fluid with a linear equation-of-state and iv)
a more physical model based on a pseudo-Nambu-Goldstone boson field. We
explicitly show the degeneracies present not only within each model but also
between the different models : they are caused by the multi-integral relation
between the equation-of-state of dark energy and the luminosity distance.
Present supernova observations are analysed using a standard $\chi^2$ method
and the minimal $\chi^2$ values obtained for each model are compared. We
confirm the difficulty to discriminate between these models using present SNeIa
data only. By means of simulations, we then show that future SNAP observations
will not remove all the degeneracies. For example, wrong estimations of
$\Omega_m$ with a good value of $\chi^2_{min}$ could be found if the right
cosmological model is not used to fit the data. We finally give some
probabilities to obtain unambiguous results, free from degeneracies. In
particular, the probability to confuse a cosmological constant with a true
barotropic fluid with an equation-of-state different from -1 is shown to be 95%
at a $2 \sigma$ level.


title:
On the origin of X-shaped radio-sources: new insights from the
  properties of their host galaxies

abstract:
  A significant fraction of extended radio sources presents a peculiar X-shaped
radio morphology: in addition to the classical double lobed structure, radio
emission is also observed along a second axis of symmetry in the form of
diffuse wings or tails. We re-examine the origin of these extensions relating
the radio morphology to the properties of their host galaxies. The orientation
of the wings shows a striking connection with the structure of the host galaxy
as they are preferentially aligned with its minor axis. Furthermore, wings are
only observed in galaxies of high projected ellipticity. Hydrodynamical
simulations of the radio-source evolution show that X-shaped radio-sources
naturally form in this geometrical situation: as a jet propagates in a
non-spherical gas distribution, the cocoon surrounding the radio-jets expands
laterally at a high rate producing wings of radio emission, in a way that is
reminiscent of the twin-exhaust model for radio-sources.


title: Physical parameters of the high-mass X-ray binary 4U1700-37

abstract:
  We present the results of a detailed non-LTE analysis of the UV and optical
spectrum of the O6.5Iaf+ star HD153919 - the mass donor in the high-mass X-ray
binary 4U1700-37. Given the eclipsing nature of the system these results allow
us to determine the most likely masses of both components of the binary via
Monte Carlo simulations. These suggest a mass for HD153919 of 58+/-11M_sun -
implying the initial mass of the companion was rather high (>60 M_sun). The
most likely mass for the compact companion is found to be 2.44+/-0.27M_sun,
with only 3.5 per cent of the trials resulting in a mass less than 2.0M_sun and
none less than 1.65M_sun. Our observational data is inconsistent with the
canonical neutron star mass and the lowest black hole mass observed (>4.4M_sun;
Nova Vel). Significantly changing observational parameters can force the
compact object mass into either of these regimes but this results in the O-star
mass changing by factors of greater than 2, well beyond the limits determined
from its evolutionary state and surface gravity. The low mass of the compact
object implies that it is difficult to form high mass black holes through both
the Case A & B mass transfer channels and, if the compact object is a neutron
star, would significantly constrain the high density nuclear EoS


title: Polarimetric observations of GRB 011211

abstract:
  We present and discuss polarimetric observations performed with the VLT-UT3
(Melipal) on the afterglow of GRB 011211, ~35 hours after the burst onset. The
observations yielded a 3-sigma upper limit of P<2.7%. We discuss this result in
combination with the lightcurve evolution, that may show a break approximately
at the time of our observation. We show that our upper limit is consistent with
the currently favored beamed fireball geometry, especially if the line of sight
was not too close to the edge of the cone.


title: High Resolution 18 Micron Imaging of Hot Molecular Cores

abstract:
  I present the latest results from a search for hot molecular cores at
mid-infrared wavelengths from the largest optical telescopes available at the
present time. Three well-observed hot molecular cores were imaged, G29.96-0.02,
G19.61-0.23, and G34.26+0.15. Even though mid-infrared sources have been
claimed to be detected previously at the hot molecular core locations of both
G19.61-0.23 and G34.26+0.15, only the hot molecular core in G29.96-0.02
resulted in a detection. New upper limits on mid-infrared emission are given
for the hot molecular cores that were not detected.


title: Are the HI deficient galaxies on the outskirts of Virgo recent arrivals?

abstract:
  The presence on the Virgo cluster outskirts of spiral galaxies with gas
deficiencies as strong as those of the inner galaxies stripped by the
intracluster medium has led us to explore the possibility that some of these
peripheral objects are not newcomers. A dynamical model for the collapse and
rebound of spherical shells under the point mass and radial flow approximations
has been developed to account for the amplitude of the motions in the Virgo I
cluster (VIC) region. According to our analysis, it is not unfeasible that
galaxies far from the cluster, including those in a gas-deficient group well to
its background, went through its core a few Gyr ago. The implications would be:
(1) that the majority of the HI-deficient spirals in the VIC region might have
been deprived of their neutral hydrogen by interactions with the hot
intracluster medium; and (2) that objects spending a long time outside the
cluster cores might keep the gas deficient status without altering their
morphology.


title: E/B decomposition of finite pixelized CMB maps

abstract:
  Separation of the E and B components of a microwave background polarization
map or a weak lensing map is an essential step in extracting science from it,
but when the map covers only part of the sky and/or is pixelized, this
decomposition cannot be done perfectly. We present a method for decomposing an
arbitrary sky map into a sum of three orthogonal components that we term ``pure
E'', ``pure B'' and ``ambiguous''. This method is useful both for providing
intuition for experimental design and for analyzing data sets in practice. We
show how to find orthonormal bases for all three components in terms of
bilaplacian eigenfunctions. The number of ambiguous modes is proportional to
the length of the map boundary so fairly round maps are preferred. For
real-world data analysis, we present a simple matrix eigenvalue method for
calculating nearly pure E and B modes in pixelized maps. We find that the
dominant source of leakage between E and B is aliasing of small-scale power
caused by the pixelization. This problem can be eliminated by heavily
oversampling the map, but is exacerbated by the fact that the E power spectrum
is expected to be much larger than the B power spectrum and extremely blue. We
found that a factor of 2 to 3 more pixels are needed in a polarization map to
achieve the same level of contamination by aliased power than in a temperature
map.


title: The peculiar cooling flow cluster RX J0820.9+0752

abstract:
  This poster is a summary of a paper on the subject (Bayer-Kim et al. 2002)
that has been submitted for publication in MNRAS. We present X-ray, H alpha,
radio, and optical data, both imaging and spectroscopy, of the cluster RX
J0820.9+0752 and its peculiar central cluster galaxy (CCG). We announce the
discovery of several isolated off-nuclear patches of blue light with strong
line-emssion (total L(H alpha) ~ 10^{42}{ergs}^{-1}) and distinct ionizational
and kinematic properties, embedded in a region of H alpha/X-ray emission. We
propose and investigate a scenario in which a secondary galaxy also featured in
our observations has moved through a cooling wake produced by the CCG, thereby
producing the observed clumpy morphology and helping to trigger star-formation
within the clumps.


title:
Statistical properties of the energy release in emerging and evolving
  active region

abstract:
  The formation and evolution of active regions is an inherently complex
phenomenon. Magnetic fields generated at the base of the convection zone follow
a chaotic evolution before reaching the solar surface. In this article, we use
a 2-D probabilistic Cellular Automaton (CA) to model the statistical properties
of the magnetic patterns formed on the solar surface and to estimate the
magnetic energy released in the interaction of opposite polarities. We assume
that newly emerged magnetic flux tubes stimulate the emergence of new magnetic
flux in their neighborhood. The flux-tubes move randomly on the surface of the
sun, and they cancel and release their magnetic energy when they collide with
magnetic flux of opposite polarity, or diffuse into the ``empty'' photosphere.
We assume that cancellation of magnetic flux in collisions causes "flares" and
determine the released energy as the difference in the square of the magnetic
field flux. The statistics of the simulated "flares" follow a power-law
distribution in energy, with power-law index a=2.2 +/- 0.1. The size
distribution function of the simulated active regions exhibits a power law
behavior with index k = 1.93 +/- 0.08, and the fractal dimension of the
magnetized areas on the simulated solar surface is close to D = 1.42 +/- 0.12.
Both quantities, D and k, are inside the range of the observed values.


title:
Nature of the Soft Spectral Component in the X-ray Pulsars SMC X-1 and
  LMC X-4

abstract:
  We present here the results of an investigation of the pulse averaged and
pulse phase resolved energy spectra of two high luminosity accretion powered
X-ray pulsars SMC X-1 and LMC X-4 made with ASCA. The phase averaged energy
spectra definitely show the presence of a soft excess in both the sources. If
the soft excess is modeled as a separate black-body or thermal bremsstrahlung
type component, pulse phase resolved spectroscopy of SMC X-1 shows that the
soft component also has a pulsating nature. Same may be true for LMC X-4,
though a very small pulse fraction limits the statistical significance. The
pulsating soft component is found to have a nearly sinusoidal profile,
dissimilar to the complex profile seen at higher energies, which can be an
effect of smearing. Due to very high luminosity of these sources, the size of
the emission zone required for the soft component is large (radius ~300-400
km). We show that the pulsating nature of the soft component is difficult to
explain if a thermal origin is assumed for it. We further investigated with
alternate models, like inversely broken power-law or two different power-law
components and found that these models can also be used to explain the excess
at low energy. A soft power-law component may be a common feature of the
accreting X-ray pulsars, which is difficult to detect because most of the HMXB
pulsars are in the Galactic plane and experience large interstellar absorption.
In LMC X-4, we have also measured two additonal mid-eclipse times, which
confirm the known orbital decay.


title:
The Effects of Alfven Waves and Radiation Pressure in Dust Winds of
  Late-type Stars

abstract:
  In the present study, we analyze the effects of a flux of Alfven waves acting
together with radiation pressure on grains as an acceleration mechanism of the
wind of late-type stars. In the wind model we simulate the presence of grains
through a strong damping of the waves, we used a non-isothermal profile for
temperature, coherent with grain formation theories. We examine the changes in
the velocity profile of the wind and we show that if the grains are created in
the region 1.1 < r/r_0 < 2.0 their presence will affect the mass loss and
terminal velocity. The model is applied to a K5 supergiant star and for
Betelgeuse (alpha Ori).


title: A New Formation Mechanism for the Hottest Horizontal-Branch Stars

abstract:
  Stars with very large mass loss on the red-giant branch can undergo the
helium flash while descending the white-dwarf cooling curve. Under these
conditions the flash convection zone will mix the hydrogen envelope with the
hot helium- burning core. Such ``flash-mixed'' stars will arrive on the extreme
horizontal branch (EHB) with helium- and carbon-rich envelopes and will lie at
higher temperatures than the hottest canonical (i.e., unmixed) EHB stars. Flash
mixing provides a new evolutionary channel for populating the hot end of the
EHB and may explain the origin of the high gravity, helium-rich sdO and sdB
stars.


title:
SWAS and Arecibo observations of H2O and OH in a diffuse cloud along the
  line-of-sight to W51

abstract:
  Observations of W51 with the Submillimeter Wave Astronomy Satellite (SWAS)
have yielded the first detection of water vapor in a diffuse molecular cloud.
The water vapor lies in a foreground cloud that gives rise to an absorption
feature at an LSR velocity of 6 km/s. The inferred H2O column density is
2.5E+13 cm-2. Observations with the Arecibo radio telescope of hydroxyl
molecules at ten positions in W51 imply an OH column density of 8E+13 cm-2 in
the same diffuse cloud. The observed H2O/OH ratio of ~ 0.3 is significantly
larger than an upper limit derived previously from ultraviolet observations of
the similar diffuse molecular cloud lying in front of HD 154368. The observed
variation in H2O/OH likely points to the presence in one or both of these
clouds of a warm (T > 400) gas component in which neutral-neutral reactions are
important sources of OH and/or H2O.


title:
On Pressure Gradients and Rapid Migration of Solids in an Inhomogeneous
  Solar Nebula

abstract:
  We study the motions of small solids, ranging from micron-sized dust grains
to 100-m objects, in the vicinity of a local density enhancement of an
isothermal gaseous solar nebula. Being interested in possible application of
the results to the formation of clumps and spiral arms in a circumstellar disk,
we numerically integrate the equations of motion of such solids and study their
migration for different values of their sizes and masses and also for different
physical properties of the gas, such as its density and temperature. We show
that, considering the drag force of the gas and also the gravitational
attraction of the nebula, it is possible for solids, within a certain range of
size and mass, to migrate rapidly (i.e. within ~1000 years) toward the location
of a local maximum density where collisions and coagulation may result in an
accelerated rate of planetesimal formation.


title: Quark color superconductivity and the cooling of compact stars

abstract:
  The thermal conductivity of the color-flavor locked phase of dense quark
matter is calculated. The dominant contribution to the conductivity comes from
photons and Nambu-Goldstone bosons associated with the breaking of baryon
number, both of which are trapped in the quark core. Because of their very
large mean free path the conductivity is also very large. The cooling of the
quark core arises mostly from the heat flux across the surface of direct
contact with the nuclear matter. As the thermal conductivity of the neighboring
layer is also high, the whole interior of the star should be nearly isothermal.
Our results imply that the cooling time of compact stars with color-flavor
locked quark cores is similar to that of ordinary neutron stars.


title: The Cosmological Constant and Dark Energy

abstract:
  Physics invites the idea that space contains energy whose gravitational
effect approximates that of Einstein's cosmological constant, Lambda; nowadays
the concept is termed dark energy or quintessence. Physics also suggests the
dark energy could be dynamical, allowing the arguably appealing picture that
the dark energy density is evolving to its natural value, zero, and is small
now because the expanding universe is old. This alleviates the classical
problem of the curious energy scale of order a millielectronvolt associated
with a constant Lambda. Dark energy may have been detected by recent advances
in the cosmological tests. The tests establish a good scientific case for the
context, in the relativistic Friedmann-Lemaitre model, including the
gravitational inverse square law applied to the scales of cosmology. We have
well-checked evidence that the mean mass density is not much more than one
quarter of the critical Einstein-de Sitter value. The case for detection of
dark energy is serious but not yet as convincing; we await more checks that may
come out of work in progress. Planned observations might be capable of
detecting evolution of the dark energy density; a positive result would be a
considerable stimulus to attempts to understand the microphysics of dark
energy. This review presents the basic physics and astronomy of the subject,
reviews the history of ideas, assesses the state of the observational evidence,
and comments on recent developments in the search for a fundamental theory.


title:
Spectroscopic survey of the Galactic open cluster NGC 6871 I. New
  emission line stars

abstract:
  We analyze spectra of 44 emission line stars detected in a low resolution
optical spectroscopic survey of the galactic open cluster NGC 6871. The survey
of 1217 stars is complete to V = 14.9 and includes stars with V < 16.5 between
the zero age main sequence (ZAMS) and the 10^7 yr pre-main sequence (PMS)
isochrone. Of the 44 emission line stars in this survey, 28 show obvious
emission in H alpha and 16 have weak H alpha absorption (compared to H gamma).
We use the reddening to separate foreground and background stars from the
cluster members; the position in the HR diagram (HRD) or the presence of
forbidden emission lines ([NII], [SII]) then yields the evolutionary status of
the emission line stars. A comparison of the H alpha spectral index
distribution in NGC 6871 with the distribution of young stars in the
Taurus-Auriga molecular cloud indicates that the late type PMS stars in our
sample may be weak line T Tauri stars (wTTs). Many of these stars show [SII]
(36%) and [NII] (45%) emission.


title: Observing Baryonic Dark Matter with ALMA

abstract:
  It has recently been argued that the unidentified SCUBA objects (USOs) are a
thick disk population of free-floating dense, compact galactic gas clumps at a
temperature of about 7 K. The characteristic mass scale is constrained to be on
the order of a Jupiter mass, and the size is about 10 AU. A typical galactic
USO is located at a distance from the sun of about 300 pc. We have calculated
the molecular emission lines from these low temperature clouds. We consider
three molecules: HD, LiH, and CO. HD is optically thin in the cloud, LiH is a
molecule with a large electric dipole moment, and CO is an abundant molecule
that is observed in dusty clouds. Our estimate for the typical object shows
that LiH may be detectable by the future sub-mm array project, ALMA; its
expected flux is at the mJy level and the line width is about $10^5$ Hz.
Although typical galactic USOs are chemically and dynamically transient, the
younger USOs will be recognisable via LiH emission if about a hundred USOs are
observed. If USOs are confirmed to be of galactic origin, the total baryonic
budget will need to be reevaluated.


title:
A Study of the Dynamics of Dust from the Kuiper Belt: Spatial
  Distribution and Spectral Energy Distribution

abstract:
  The dust produced in the Kuiper Belt (KB) spreads throughout the Solar System
forming a dust disk. We numerically model the orbital evolution of KB dust and
estimate its equilibrium spatial distribution and its brightness and spectral
energy distributions (SED), assuming greybody absorption and emission by the
dust grains. We show that the planets modify the KB disk SED, so potentially we
can infer the presence of planets in spatially unresolved debris disks by
studying the shape of their SEDs. We point out that there are inherent
uncertainties in the prediction of structure in the dust disk, owing to the
chaotic dynamics of dust orbital evolution imposed by resonant gravitational
perturbations of the planets.


title:
The use of luminosity effects to calculate scaling regimes in the galaxy
  distribution

abstract:
  This work is a continuation of a previous publication {Thieberger and
Spiegel,astro-ph/0204485} concerning the use of two dimensional catalogues in
unraveling the large scale distribution of galaxies. Since the data in
two-dimensional catalogues are more plentiful than those in three dimensions,
the luminosity method can be helpful in using two dimensional data to unravel
the nature of the three dimensional distribution. In this work we analyse the
Cfa catalogue and demonstrate that the results indicate a distribution of two
dimensions in the nearer range and three dimensions in the farther range. The
possibility of a different regime for very short distances is discussed.


title: TESIS - The TNG EROs Spectroscopic Identification Survey

abstract:
  A near-IR low-resolution spectroscopic follow-up of a complete sample of
K<18.5 EROs has started at the 3.5 m Telescopio Nazionale Galileo (TNG, La
Palma, Canary Islands) by using a prism disperser AMICI. The sample has been
selected from the Munich Near-IR Cluster Survey (MUNICS). The project aims at
revealing massive galaxies at z>1.2 and at estimating their spatial density to
put constraints on the galaxy formation and evolution models. In this
proceeding, the preliminary analysis of the first spectra obtained is
presented.


title:
Morphological Redshift Estimates for Galaxy Clusters in a
  Sunyaev-Zel'dovich Effect Survey

abstract:
  We develop a new method to estimate the redshift of galaxy clusters through
resolved images of the Sunyaev-Zel'dovich effect (SZE). Our method is based on
morphological observables which can be measured by actual and future SZE
experiments. We test the method with a set of high resolution hydrodynamical
simulations of galaxy clusters at different redshifts. Our method combines the
observables in a principal component analysis. After calibrating the method
with an independent redshift estimation for some of the clusters, we show -
using a Bayesian approach - how the method can give an estimate of the redshift
of the galaxy clusters. Although the error bars given by the morphological
redshift estimation are large, it should be useful for future SZE surveys where
thousands of clusters are expected to be detected; a first preselection of the
high redshift candidates could be done using our proposed morphological
redshift estimator. Although not considered in this work, our method should
also be useful to give an estimate of the redshift of clusters in X-ray and
optical surveys.


title:
Hot Bubbles from Active Galactic Nuclei as a Heat Source in Cooling Flow
  Clusters

abstract:
  The hot plasma permeating clusters of galaxies often shows a central peak in
the X-ray surface brightness that is coincident with a drop in entropy. This is
taken as evidence for a cooling flow where the radiative cooling in the central
regions of a cluster causes a slow subsonic inflow. Searches in all wavebands
have revealed significantly less cool gas than predicted indicating that the
mass deposition rate of cooling flows is much lower than expected. However,
most cooling flow clusters host an Active Galactic Nucleus (AGN) at their
centres. AGN can inflate large bubbles of hot plasma that subsequently rise
through the cluster atmosphere, thus stirring this gas. Here we report on the
results from highly resolved hydrodynamic simulations which for the first time
show that buoyant bubbles increase the cooling time in the inner cluster
regions and thereby significantly reduce the deposition of cold gas. This work
demonstrates that the action of AGN in the centres of cooling flow clusters can
explain the observed absence of large quantities of cooled gas.


title:
Broad-band continuum and line emission of the gamma-ray blazar PKS
  0537-441

abstract:
  PKS 0537-441, a bright gamma-ray emitting blazar, was observed at radio,
optical, UV and X-ray frequencies during various EGRET pointings, often
quasi-simultaneously. In 1995 the object was found in an intense emission state
at all wavelengths. BeppoSAX observations made in 1998, non-simultaneously with
exposures at other frequencies, allow us to characterize precisely the spectral
shape of the high energy blazar component, which we attribute to inverse
Compton scattering. The optical-to-gamma-ray spectral energy distributions at
the different epochs show that the gamma-ray luminosity dominates the
bolometric output. This, together with the presence of optical and UV line
emission, suggests that, besides the synchrotron self-Compton mechanism, the
Compton upscattering of photons external to the jet (e.g., in the broad line
region) may have a significant role for high energy radiation. The
multiwavelength variability can be reproduced by changes of the plasma bulk
Lorentz factor. The spectrum secured by IUE in 1995 appears to be partially
absorbed shortward of ~1700 A. However, this signature is not detected in the
HST spectrum taken during a lower state of the source. The presence of
intervening absorbers is not supported by optical imaging and spectroscopy of
the field.


title:
Consistent beta values from density-density and velocity-velocity
  comparisons

abstract:
  We apply a new algorithm, called the Unbiased Minimal Variance (hereafter
UMV) estimator, to reconstruct the cosmic density and peculiar velocity fields
in our local universe from the SEcat catalog of peculiar velocities comprising
both early (ENEAR) and late type (SFI) galaxies. The reconstructed fields are
compared with those predicted from the IRAS PSCz galaxy redshift survey to
constrain the value of beta = Omega_m^{0.6}/b, where Omega_m and b are the mass
density and the bias parameters. The comparison of the density and velocity
fields is carried out within the same methodological framework, and leads, for
the first time, to consistent values of beta, yielding beta =
0.57_{-0.13}^{+0.11} and beta = 0.51 +/- {0.06}, respectively.
  We find that the distribution of the density and velocity residuals, relative
to their respective errors, is consistent with a Gaussian distribution with
sigma approximately 1, indicating that the density field predicted from the
PSCz is an acceptable fit to that deduced from the peculiar velocities of the
SEcat galaxies.


title:
Analytic Approaches to Understanding the Distribution and Evolution of
  Intracluster Gas

abstract:
  I will briefly review various analytic approaches to understanding the
contents and properties of the hot X-ray emitting gas contained in clusters and
groups. Special emphases are given to the following three issues:
(1)Reconstruction of the gas distribution in groups and clusters from a (joint)
analysis of X-ray, SZ and gravitational lensing observations; (2)Test of the
analytic density profiles of dark halos suggested by numerical simulations and
empirical models with current X-ray data; And (3)the effects of preheating and
radiative cooling on the X-ray properties of groups and clusters.


title: Galaxy Evolution: Internally or Externally Driven?

abstract:
  The globally-averaged star formation rate in the Universe has been steadily
declining since at least z~1. This may be due either to very local processes
operating within the average galaxy, or to external, environmental effects.
Specifically, the build-up of structure may be responsible for terminating star
formation in some galaxies and thus decreasing the global average. We summarize
our previous and ongoing work to distinguish between these possibilities, by
determining the average star formation rate as a function of redshift and
environment, out to z=0.5.


title: TeV Neutrinos from Galactic Microquasar Jets

abstract:
  We discuss the possibility that microquasar jets may be powerful emitters of
TeV neutrinos. We estimate the neutrino fluxes produced by photopion production
in the jets of a sample of identified microquasars and microquasar candidates,
for which available data enables rough determination of the jet parameters. We
demonstrate that in several of the sources considered, the neutrino flux at
Earth, produced in events similar to those observed, can exceed the detection
threshold of a km^2 neutrino detector. Sources with bulk Lorentz factors larger
than those characteristic of the sample considered here, directed along our
line of sight may be very difficult to resolve at radio wavelengths and hence
may be difficult to identify as microqusar candidates. However these sources
can be identified through their neutrino and gamma-ray emission.


title: Galaxy Properties in Low X-Ray Luminosity Clusters at z=0.25

abstract:
  We present the first spectroscopic survey of intrinsically low Lx clusters at
z>>0, with HST WFPC2 imaging and ground-based spectroscopy. We study 172
confirmed cluster members in a sample of ten clusters at z=0.23-0.3, with
Lx<4.E43 h^{-2} ergs/s. The core of each cluster is imaged with WFPC2 in the
F702W filter, and the spectroscopic sample is statistically complete to
Mr-19.0+5log(h), within an 11' field. The clusters are dynamically
well-separated from the surrounding field and the velocity dispersions range
from ~350-850 km/s. Emission line galaxies in these clusters are relatively
rare, comprising only 22 +/- 4% of the sample. There is no evidence that these
emission-line galaxies are dynamically distinct from the majority of the
cluster population, though our sample is too small to rule out the ~30%
difference that has been observed in more massive clusters. We find eleven
galaxies, comprising 6% of the cluster members, which are disk-dominated but
show no sign of emission in their spectrum. Most of these are relatively
isolated, spiral galaxies with smooth disks. We find no cluster members with a
starburst or post-starburst spectrum. The striking similarity between the
spectral and morphological properties of galaxies in these clusters and those
of galaxies in more massive systems at similar redshifts implies that the
physical processes responsible for truncating star formation in galaxies are
not restricted to the rare, rich cluster environment, but are viable in much
more common environments. In particular, we conclude that ram pressure
stripping or cluster-induced starbursts cannot be solely responsible for the
low star formation rates in these systems.


title: Gamma rays from clusters of galaxies

abstract:
  The search for gamma radiation in clusters of galaxies represents a precious
tool to investigate the history of these large scale structures. Clusters or
sources within them accelerate cosmic rays, as demonstrated by the detection of
radio halos, hard X-rays and UV emission, and confine them over cosmological
time scales. Nonthermal and thermal phenomena may be closely related and
observations of gamma rays may tell us about this link. In this paper we review
the physics of cosmic ray acceleration and confinement in clusters of galaxies
and the related gamma ray signatures. In particular we describe in some detail
the role of cluster mergers for the acceleration of nonthermal particles. The
perspectives for gamma ray detection with GLAST and with ground based detectors
are also discussed.


title:
XMM-Newton and Chandra view of the Cluster Abell 85 and its X-Ray
  Filament

abstract:
  From ROSAT data, the bright X-ray cluster Abell 85 was found to show a
roughly symmetrical shape, on to which are superimposed several features, among
which: (1) a blob or group of galaxies falling on to the main cluster, with the
gas in the impact region probably hotter and the galaxies in that zone showing
enhanced star formation; (2) a filament, either diffuse or made of small groups
of galaxies, extending at least 4 Mpc from the cluster (Durret et al. 1998).
Preliminary results obtained from XMM-Newton and Chandra observations of Abell
85 and its filament will be presented.


title:
Grain Formation in Post-Shocked Wind Collisions of Massive Binary
  Systems

abstract:
  Massive binary star systems are not uncommon, and neither the supersonic
collision of their winds. In the present work we study these shocks and the
further consequences on wind structure. The post-shock gas is a warm and
high-density environment, which allows dust to form and grow. We show that this
growth is fast, of just a few hours. An application for etaCarinae shows that,
probably, the decline of X-rays fluxes observed in its light curve is the
consequence of its high absorption in periodic dust formation events, on the
periastron passage.


title: Revised NLTT

abstract:
  Revised NLTT (New Luyten Catalogue of Stars With Proper Motions Larger than
Two Tenths of an Arcsecond) contains improved astrometry and new
optical/infrared photometry for the vast majority of NLTT stars lying in the
overlap of regions covered by POSS I and by the 2MASS release, approximately
44% of the sky. The epoch 2000 positions are typically accurate to 130 mas, the
proper motions to 5.5 mas/yr, and the V-J colors to 0.25 mag. Relative proper
motions of binary components are meaured to 3 mas/yr. The false identification
rate is ~1% for 11 < V < 18 and substantially less at brighter magnitudes.


title: Studying the Gaseous Phases of Galaxies with Background QSOs

abstract:
  High resolution rest frame UV quasar absorption spectra covering low and high
ionization species, as well as the Lyman series lines, provide remarkably
detailed information about the gaseous phases of galaxies and their
environments. For redshifts less than 1.5, many important chemical transitions
remain in the observed ultraviolet wavelength range. I present examples of
absorption that arises from lines of sight through a variety of structures,
drawn from UV spectra recently obtained with STIS/HST. Even with the greater
sensitivity of COS/HST there will be a limit to how many systems can be studied
in detail. However, there is a great variety in the morphology of the phases of
gas that we observe, even passing through different regions of the same galaxy.
In order to compile a fair sample of the gaseous structures present during
every epoch of cosmic history, hundreds of systems must be sampled. Multiple
lines of sight through the same structures are needed, as well as some probing
nearby structures whose luminous hosts have been studied with more standard
techniques. Combined with high resolution optical and near--IR ground--based
spectra, it will be possible to uniformly study the gaseous morphologies of
galaxies of all types through their entire evolutionary histories.


title: Effect of halo modelling on WIMP exclusion limits

abstract:
  WIMP direct detection experiments are just reaching the sensitivity required
to detect galactic dark matter in the form of neutralinos. Data from these
experiments are usually analysed under the simplifying assumption that the
Milky Way halo is an isothermal sphere with maxwellian velocity distribution.
Observations and numerical simulations indicate that galaxy halos are in fact
triaxial and anisotropic. Furthermore, in the cold dark matter paradigm
galactic halos form via the merger of smaller subhalos, and at least some
residual substructure survives. We examine the effect of halo modelling on WIMP
exclusion limits, taking into account the detector response. Triaxial and
anisotropic halo models, with parameters motivated by observations and
numerical simulations, lead to significant changes which are different for
different experiments, while if the local WIMP distribution is dominated by
small scale clumps then the exclusion limits are changed dramatically.


title:
Global dynamics and stability limits for planetary systems around HD
  12661, HD 38529, HD 37124 and HD 160691

abstract:
  In order to distinguish between regular and chaotic planetary orbits we apply
a new technique called MEGNO in a wide neighbourhood of orbital parameters
determined using standard two-body Keplerian fits for HD 12661, HD 38529, HD
37124 and HD 160691 planetary systems. We show that the currently announced
orbital parameters place these systems in very different situations from the
point of view of dynamical stability. While HD 38529 and HD 37124 are located
within large stability zones in the phase space around their determined orbits,
the preliminary orbits in HD 160691 are highly unstable. The orbital parameters
of the HD 12661 planets are located in a border region between stable and
unstable dynamical regimes, so while its currently determined orbital
parameters produce stable regular orbits, a minor change within the margin of
error of just one parameter may result in a chaotic dynamical system.


title: Detection of Water Vapor in the Photosphere of Arcturus

abstract:
  We report detections of pure rotation lines of OH and H2O in the K1.5 III
red-giant star Arcturus (alpha Bootis) using high-resolution, infrared spectra
covering the regions 806-822 cm-1 (12.2-12.4 um) and 884-923 cm-1 (10.8-11.3
um). Arcturus is the hottest star yet to show water-vapor features in its
disk-averaged spectrum. We argue that the water vapor lines originate from the
photosphere, albeit in the outer layers. We are able to predict the observed
strengths of OH and H2O lines satisfactorily after lowering the temperature
structure of the very outer parts of the photosphere (log tau_500=-3.8 and
beyond) compared to a flux-constant, hydrostatic, standard MARCS model
photosphere. Our new model is consistently calculated including chemical
equilibrium and radiative transfer from the given temperature structure.
Possible reasons for a temperature decrease in the outer-most parts of the
photosphere and the assumed break-down of the assumptions made in classical
model-atmosphere codes are discussed.


title:
Gravitational Potential Reconstruction from Peculiar Velocity and Weak
  Lensing Measurements

abstract:
  We present an analytic method for rapidly forecasting the accuracy of
gravitational potential reconstruction possible from measurement of radial
peculiar velocities of every galaxy cluster with M > M_th in solid angle
\theta^2 and over redshift range z_min < z < z_max. These radial velocities can
be determined from measurement of the kinetic and thermal Sunyaev-Zeldovich
effects. For a shallow survey with 0.2 < z < 0.4, coincident with the SDSS
photometric survey, one mode of the gravitational potential (on length scales >
60 Mpc) can be reconstructed for every ~8 cluster velocity determinations.
Deeper surveys require measurement of more clusters per S/N > 1 mode. Accuracy
is limited by the ``undersampling noise'' due to our non-observation of the
large fraction of mass that is not in galaxy clusters. Determining the
gravitational potential will allow for detailed study of the relationship
between galaxies and their surrounding large-scale density fields over a wide
range of redshifts, and test the gravitational instability paradigm on very
large scales. Observation of weak lensing by large-scale structure provides
complementary information since lensing is sensitive to the tangential modes
that do not affect the velocity.


title: A Magnetically Torqued Disk Model for Be Stars

abstract:
  Despite extensive study, the mechanisms by which Be star disks acquire high
densities and angular momentum while displaying variability on many time scales
are still far from clear. In this paper, we discuss how magnetic torquing may
help explain disk formation with the observed quasi-Keplerian (as opposed to
expanding) velocity structure and their variability. We focus on the effects of
the rapid rotation of Be stars, considering the regime where centrifugal forces
provide the dominant radial support of the disk material. Using a kinematic
description of the angular velocity, vphi(r), in the disk and a parametric
model of an aligned field with a strength B(r) we develop analytic expressions
for the disk properties that allow us to estimate the stellar surface field
strength necessary to create such a disk for a range of stars on the
main-sequence. The model explains why disks are most common for main-sequence
stars at about spectral class B2 V. The earlier type stars with very fast and
high density winds would require unacceptably strong surface fields (> 10^3
Gauss) to form torqued disks, while the late B stars (with their low mass loss
rates) tend to form disks that produce only small fluxes in the dominant Be
diagnostics. For stars at B2 V the average surface field required is about 300
Gauss. The predicted disks provide an intrinsic polarization and a flux at
Halpha comparable to observations. We also discuss whether the effect on field
containment of the time dependent accumulation of matter in the flux tubes/disk
can help explain some of the observed variability of Be star disks.


title: On The Determination of MDI High-Degree Mode Frequencies

abstract:
  The characteristic of the solar acoustic spectrum is such that mode lifetimes
get shorter and spatial leaks get closer in frequency as the degree of a mode
increases for a given order. A direct consequence of this property is that
individual p-modes are only resolved at low and intermediate degrees, and that
at high degrees, individual modes blend into ridges. Once modes have blended
into ridges, the power distribution of the ridge defines the ridge central
frequency and it will mask the true underlying mode frequency. An accurate
model of the amplitude of the peaks that contribute to the ridge power
distribution is needed to recover the underlying mode frequency from fitting
the ridge.
  We present the results of fitting high degree power ridges (up to l = 900)
computed from several two to three-month-long time-series of full-disk
observations taken with the Michelson Doppler Imager (MDI) on-board the Solar
and Heliospheric Observatory between 1996 and 1999.
  We also present a detailed discussion of the modeling of the ridge power
distribution, and the contribution of the various observational and
instrumental effects on the spatial leakage, in the context of the MDI
instrument. We have constructed a physically motivated model (rather than some
ad hoc correction scheme) resulting in a methodology that can produce an
unbiased determination of high-degree modes, once the instrumental
characteristics are well understood.
  Finally, we present changes in high degree mode parameters with epoch and
thus solar activity level and discuss their significance.


title:
On the Feasibility of Detecting Satellites of Extrasolar Planets via
  Microlensing

abstract:
  Although many methods of detecting extra-solar planets have been proposed and
successful implementation of some of these methods enabled a rapidly increasing
number of exoplanet detections, little has been discussed about the method of
detecting satellites around exoplanets. In this paper, we test the feasibility
of detecting satellites of exoplanets via microlensing. For this purpose, we
investigate the effect of satellites in the magnification pattern near the
region of the planet-induced perturbations by performing realistic simulations
of Galactic bulge microlensing events. From this investigation, we find that
although satellites can often cause alterations of magnification patterns,
detecting satellite signals in lensing light curves will be very difficult
because the signals are seriously smeared out by the severe finite source
effect even for events involved with source stars with small angular radii.


title:
Optical and Near-Infrared Imaging of the IRAS 1-Jy Sample of
  Ultraluminous Infrared Galaxies: I. The Atlas

abstract:
  An imaging survey of the {\em IRAS} 1-Jy sample of 118 ultraluminous infrared
galaxies was conducted at optical (R) and near-infrared (K') wavelengths using
the University of Hawaii 2.2m telescope. The methods of observation and data
reduction are described. An R and K' atlas of the entire sample is presented
along with some of the basic astrometric and photometric parameters derived
from these images. A more detailed analysis of these data is presented in a
companion paper (Veilleux, Kim, & Sanders 2002; astro-ph/0207401).


title: MC3D - 3D Continuum Radiative Transfer, Version 2

abstract:
  A revised and greatly improved version of the 3D continuum radiative transfer
code MC3D is presented. It is based on the Monte-Carlo method and solves the
radiative transfer problem self-consistently. It is designed for the simulation
of dust temperatures in arbitrary geometric configurations and the resulting
observables: spectral energy distributions, wavelength-dependent images, and
polarization maps. The main objective is the investigation of
``dust-dominated'' astrophysical systems such as young stellar objects
surrounded by an optically thick circumstellar disk and an optically thin(ner)
envelope, debris disks around more evolved stars, asymptotic giant branch
stars, the dust component of the interstellar medium, and active galactic
nuclei.


title: Cosmological Fluctuations of Short Wavelength

abstract:
  This paper presents a completely analytic treatment of cosmological
fluctuations whose wavelength is small enough to come within the horizon well
before the energy densities of matter and radiation become equal. This analysis
yields a simple formula for the conventional transfer function T(k) at large
wave number k, which agrees very well with computer calculations of T(k). It
also yields an explicit formula for the microwave background multipole
coefficient C_ell at very large ell.


title:
High Resolution Ultraviolet Quasar Absorption Line Spectroscopy of z~1
  Galaxy Group

abstract:
  We used ultraviolet spectra from HST/STIS (R=30,000), together with optical
spectra from Keck/HIRES (R=45,000), to study the three MgII-selected absorption
systems at z=0.9254, 0.9276, and 0.9342 toward the quasar PG 1206+459. A
multi-phase gaseous structure, with low-ionization components produced in small
condensations and high-ionization ones in diffuse clouds, is indicated in all
three systems. Each system is likely to represent a different galaxy with
absorption due to some combination of interstellar medium, coronal gas, halo
gas, and high-velocity clouds. Even with the improved sensitivity of HST/COS,
we will only be able to obtain high-resolution ultraviolet spectra of the
brightest quasars in the sky. A larger telescope with ultraviolet coverage will
enable quasar absorption line studies of hundreds of galaxies, including a wide
range of galaxy types and environments at low and intermediate redshifts.


title:
Three-Dimensional Genus Statistics of Galaxies in the SDSS Early Data
  Release

abstract:
  We present the first analysis of three-dimensional genus statistics for the
SDSS EDR galaxy sample. Due to the complicated survey volume and the selection
function, analytic predictions of the genus statistics for this sample are not
feasible, therefore we construct extensive mock catalogs from N-body
simulations in order to compare the observed data with model predictions. This
comparison allows us to evaluate the effects of a variety of observational
systematics on the estimated genus for the SDSS sample, including the shape of
the survey volume, the redshift distortion effect, and the radial selection
function due to the magnitude limit. The observed genus for the SDSS EDR galaxy
sample is consistent with that predicted by simulations of a
$\Lambda$-dominated spatially-flat cold dark matter model. Standard
($\Omega_0=1$) cold dark matter model predictions do not match the
observations. We discuss how future SDSS galaxy samples will yield improved
estimates of the genus.


title: Mrk 1014: An AGN Dominated ULIRG at X-rays

abstract:
  In this paper we report on an XMM-Newton observation of the ultraluminous
infrared QSO Mrk 1014. The X-ray observation reveals a power-law dominated
(photon index of about 2.2) spectrum with a slight excess in the soft energy
range. AGN and starburst emission models fit the soft excess emission equally
well, however, the most plausible explanation is an AGN component as the
starburst model parameter, temperature and luminosity, appear physically
unrealistic. The mean luminosity of Mrk 1014 is about 2 times 10^44 erg s^-1.
We have also observed excess emission at energies greater than 5 keV. This
feature could be attributed to a broadened and redshifted iron complex, but
deeper observations are required to constrain its origin. The light curve shows
small scale variability over the 11 ks observation. There is no evidence of
intrinsic absorption in Mrk 1014. The X-ray observations support the notion of
an AGN dominated central engine. We establish the need for a longer observation
to constrain more precisely the nature of the X-ray components.


title:
Dust emission from inhomogeneous interstellar clouds: radiative transfer
  in 3D with transiently heated particles

abstract:
  We present a numerical code for continuum radiative transfer that is based on
the idea of a `library' describing the relation between the intensity of the
local radiation field and the resulting dust emission. With this information
and local intensities at a few reference wavelengths, the radiative transfer
equation can be integrated through the source and an approximation of the
emission spectrum is obtained. Tests with small models for which the radiative
transfer problem can be solved directly show that with our method one can
easily obtain an accuracy of a few per cent. We show spectra computed from
three-dimensional MHD simulations containing up to 128^3 cells. The models
represent starless, inhomogeneous interstellar clouds embedded in the normal
interstellar radiation field. The intensity ratios between IRAS bands show
large variations that follow the filamentary density distribution. The power
law index of the spatial power spectrum of the column density map is -2.8. In
infrared maps temperature variations increase the power at high spatial
frequencies, and the index varies between -2.5 and -2.7. Assuming constant dust
properties throughout the cloud, the IRAS ratio <I_60/I_100> decreases in
densest cores only by a factor of ~4 compared with the value in diffuse medium.
In observations the ratio can decrease twice as much even in optically thinner
clouds. This requires that most of the small grains are removed in these
regions, and possibly a modification of the properties of large grains.


title: Redshift of Galaxy Clusters from the Sunyaev-Zel'dovich effect

abstract:
  We develop a new method for estimating the redshift of galaxy clusters
through resolved images of the Sunyaev-Zel'dovich effect (SZE). Our method is
based on morphological observables which can be measured by actual and future
SZE experiments. The method is tested using a set of high resolution
hydrodynamical simulations of galaxy clusters at different redshifts. The
method combines the observables in a principal component analysis. We show how
this can give an estimate of the redshift of the galaxy clusters. Although the
uncertainty in the redshift estimation is large, the method should be useful
for future SZE surveys where hundreds of clusters are expected to be detected.
A first preselection of the high redshift candidates could be done using our
proposed morphological redshift estimator.


title:
Mid-Infrared line diagnostics of Active Galaxies -- A spectroscopic AGN
  survey with ISO-SWS

abstract:
  We present medium resolution (R approx. 1500) ISO-SWS 2.4--45 micron spectra
of a sample of 29 galaxies with active nuclei. This data set is rich in fine
structure emission lines tracing the narrow line regions and (circum-)nuclear
star formation regions, and it provides a coherent spectroscopic reference for
future extragalactic studies in the mid-infrared. We use the data set to
briefly discuss the physical conditions in the narrow line regions (density,
temperature, excitation, line profiles) and to test for possible differences
between AGN sub-types. Our main focus is on new tools for determining the
propertibes of dusty galaxies and on the AGN-starburst connection. We present
mid-IR line ratio diagrams which can be used to identify composite (starburst +
AGN) sources and to distinguish between emission excited by active nuclei and
emission from (circum-nuclear) star forming regions. For instance, line ratios
of high to low excitation lines like [O IV]25.9um/[Ne II]12.8um, that have been
used to probe for AGNs in dusty objects, can be examined in more detail and
with better statistics now. In addition, we present two-dimensional diagnostic
diagrams that are fully analogous to classical optical diagnostic diagrams, but
better suited for objects with high extinction. Finally, we discuss
correlations of mid-infrared line fluxes to the mid- and far-infrared
continuum. We compare these relations to similar relations in starburst
galaxies in order to examine the contribution of AGNs to the bolometric
luminosities of their host galaxies. The spectra are available in electronic
form from the authors.


title: On the use of 12CO/13CO as a test of common-envelope evolution

abstract:
  We present K-band echelle spectra of the cataclysmic variable SS Cyg and the
pre-cataclysmic variable V471 Tau in order to measure the strengths of the 12CO
and 13CO bands at 2.3525 and 2.3448 microns, respectively, and so perform the
observational test of the common-envelope model of close binary star evolution
proposed by Sarna et al. (1995). Although we find evidence of an absorption
feature coincident with the expected wavelength of 13CO in both objects, we
attribute it instead to a cluster of neutral atomic absorption features
(primarily due to TiI) possibly arising from star-spots on the surfaces of the
rapidly rotating secondary stars in these systems, thereby rendering the test
inconclusive. We present a modified observational test of common-envelope
evolution, based on the observation of the 13CO bands at 2.3739 and 2.4037
microns, which is insensitive to spectral contamination by star-spots.


title: Mass Outflow from the X-ray Binary X2127+119 in M15

abstract:
  The bright X-ray binary X2127+119 in the core of the globular cluster M15 has
long been thought to be in an unusual evolutionary state, in which the binary
is embedded in a common envelope. Support for this idea comes from X2127+119's
absorption lines, which are blue shifted at all orbital phases, indicating the
existence of outflows from the system. A common-envelope scenario implies that
the absorption lines should exhibit maximum blue shift near mid-eclipse (binary
phase 0.0). We have re-analysed INT spectra of X2127+119 obtained in 1986, 1987
and 1988 using the latest orbital ephemeris (substantially different from that
used in the original analysis), and find that the orbital phase at which the
absorption lines show a maximum blue shift is not 0.0, but rather 0.25 -- 0.3.
These results indicate that a common-envelope scenario for X2127+119 may not
work. In addition, from spectrograms of the He II 4686 line, we report the
first tentative detection of X2127+119's companion star.


title: Modelling Oscillations in GRS 1915+105 Jet Emission

abstract:
  We have studied time variability in the flux from the flat spectrum
synchrotron radiation of the Blandford & Konigl (1979) model for relativistic,
conical jets. The resulting model has been applied to the flux variation of the
flat spectrum of GRS 1915+105 observed by Fender & Pooley (2000). This
comparison has highlighted a fundamental problem of the Blandford & Konigl
(1979) model in that it requires unphysically large electron densities to
explain the flux levels observed from the flat spectrum of GRS 1915+105.


title: Thermal Emission as a Test for Hidden Nuclei in Nearby Radio Galaxies

abstract:
  The clear sign of a hidden quasar inside a radio galaxy is the appearance of
quasar spectral features in its polarized (scattered) light. However that
observational test requires suitably placed scattering material to act as a
mirror, allowing us to see the nuclear light. A rather robust and more general
test for a hidden quasar is to look for the predicted high mid-IR luminosity
from the nuclear obscuring matter. The nuclear waste heat is detected and well
isolated in the nearest narrow line radio galaxy, Cen A. This confirms other
indications that Cen A does contain a modest quasar-like nucleus. However we
show here that M87 does not: at high spatial resolution, the mid-IR nucleus is
seen to be very weak, and consistent with simple synchrotron emission from the
base of the radio jet. This fairly robustly establishes that there are "real"
narrow line radio galaxies, without the putative accretion power, and with
essentially all the luminosity in kinetic form. Next we show the intriguing
mid-IR morphology of Cygnus A, reported previously by us and later discussed in
detail by Radomski et al. (2002). All of this mid-IR emission is consistent
with reprocessing by a hidden quasar, known to exist from spectropolarimetry by
Ogle et al. (1997) and other evidence.


title: The Hard Truth about Some "Soft" X-ray Transients

abstract:
  We have accumulated multiwavelength lightcurves for eight black hole X-ray
binaries which have been observed to enter a supposed ``soft X-ray transient''
outburst, but which in fact remained in the low/hard state throughout the
outburst. Comparison of the lightcurve morphologies, spectral behaviour,
properties of the QPOs and the radio jet provides the first study of such
objects as a subclass of X-ray transients (XRTs). However, rather than assuming
that these hard state XRTs are different from ``canonical'' soft XRTs, we
prefer to consider the possibility that a new analysis of both soft and hard
state XRTs in a spectral context will provide a model capable of explaining the
outburst mechanisms for the majority of black hole X-ray binaries.


title: Kinematic Linkage Between the Broad and Narrow Line Emitting Gas in AGN

abstract:
  We investigate the radial velocity difference between the [OIII]5007,4959 and
H-beta lines for a sample of 200 low redshift AGN. We identify seven objects
showing an [OIII]5007 blueshift relative to H-beta with amplitude larger than
250 km/s (blue "outliers"). These line shifts are found in sources where the
broad high ionization lines (e.g. CIV1549) also show a large systematic
blueshift. Such blueshifts occur only in the population A region of the
Eigenvector 1 parameter domain (that also contains NLSy1 sources). We suggest
that [OIII] blueshifts are also associated with the high ionization outflow
originating in these sources. This is a direct kinematic linkage between narrow
and broad line emitting gas.