220 research outputs found
The warm interstellar medium around the Cygnus Loop
Observations of the oxygen lines [OII]3729 and [OIII]5007 in the medium
immediately beyond the Cygnus Loop supernova remnant were carried out with the
scanning Fabry-P\'erot spectrophotometer ESOP. Both lines were detected in
three different directions - east, northeast and southwest - and up to a
distance of 15 pc from the shock front. The ionized medium is in the immediate
vicinity of the remnant, as evinced by the smooth brightening of both lines as
the adiabatic shock transition (defined by the X-ray perimeter) is crossed.
These lines are usually brighter around the Cygnus Loop than in the general
background in directions where the galactic latitude is above 5 degrees. There
is also marginal (but significant) evidence that the degree of ionization is
somewhat larger around the Cygnus Loop. We conclude that the energy necessary
to ionize this large bubble of gas could have been supplied by an O8 or O9 type
progenitor or the particles heated by the expanding shock front. The second
possibility, though highly atractive, would have to be assessed by extensive
modelling.Comment: 18 pages, 8 figures, ApJ 512 in pres
The distant galaxy cluster CL0016+16: X-ray analysis up to
To study the mass distribution of galaxy clusters up to their Virial radius,
CL0016+16 seems to be a good candidate,since it is a bright massive cluster,
previously considered as being dynamically relaxed. Using XMM-Newton
observations of CL0016+16, we performed a careful X-ray background analysis,
and we detected convincingly its X-ray emission up to . We then
studied its dynamical state with a detailed 2D temperature and surface
brightness analysis of the inner part of the cluster. Using the assumption of
both spherical symmetry and hydrostatic equilibrium (HE) we can determine the
main cluster parameters: total mass, temperature profile, surface brightness
profile and -parameter. We also build a temperature map which clearly
exhibits departure from spherical symmetry in the centre. To estimate the
influence of these perturbations onto our total mass estimate, we also compute
the total mass in the framework of the HE approach, but this time with various
temperature profiles obtained in different directions. These various total mass
estimates are consistent with each other. The temperature perturbations are
clear signatures of ongoing merger activity. We also find significant residuals
after subtracting the emissivity map by a 2D -model fit. We conclude
that, although CL0016+16 shows clear signs of merger activity and departure
from spherical symmetry in the centre, its X-ray emissivity can be detected up
to and the corresponding mass can be computed directly. It
is therefore a good candidate to study cosmological scaling laws as predicted
by the theory.Comment: 11 pages, 17 figures, Accepted for publication in A&
A noncommutative Sierpinski gasket
A quantized version of the Sierpinski gasket is proposed, on purely topological grounds, as a C*-algebra A infinity with a suitable form of self-similarity. Several properties of A infinity are studied, in particular its nuclearity, the structure of ideals as well as the description of irreducible representations and extremal traces. A harmonic structure is introduced, giving rise to a self-similar Dirichlet form E. A spectral triple is also constructed, extending the one already known for the classical gasket, from which E can be reconstructed. Moreover we show that A infinity is a compact quantum metric space
A planar calculus for infinite index subfactors
We develop an analog of Jones' planar calculus for II_1-factor bimodules with
arbitrary left and right von Neumann dimension. We generalize to bimodules
Burns' results on rotations and extremality for infinite index subfactors.
These results are obtained without Jones' basic construction and the resulting
Jones projections.Comment: 56 pages, many figure
Anti-tuberculosis drug resistance survey in West Nile, Uganda
IUATLD Conference, Paris, 200
Fredholm Modules on P.C.F. Self-Similar Fractals and their Conformal Geometry
The aim of the present work is to show how, using the differential calculus
associated to Dirichlet forms, it is possible to construct Fredholm modules on
post critically finite fractals by regular harmonic structures. The modules are
d-summable, the summability exponent d coinciding with the spectral dimension
of the generalized laplacian operator associated with the regular harmonic
structures. The characteristic tools of the noncommutative infinitesimal
calculus allow to define a d-energy functional which is shown to be a
self-similar conformal invariant.Comment: 16 page
An XMM-Newton study of the sub-structure in M87's halo
The high signal to noise and good point spread function of XMM have allowed
the first detailed study of the interaction between the thermal and radio
emitting plasma in the central regions of M87. We show that the X-ray emitting
structure, previously seen by ROSAT, is thermal in nature and that the east and
southwest extensions in M87's X-ray halo have a significantly lower temperature
(kT= 1.5 keV) than the surrounding ambient medium (kT= 2.3 keV). There is
little or no evidence for non-thermal emission with an upper limit on the
contribution of a power law component of spectral index flatter than 3 being
less than 1% of the flux in the region of the radio lobes.Comment: 6 pages, 8 color figures, to be published in A&A, number 36
Good immune restitution but unsatisfactory viral suppression in children on ART in a remote Western Kenya area
Mexico AIDS Conference 200
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