9,546 research outputs found
A method to resolve the nuclear activity in galaxies, as applied to NGC1358
Nuclear regions of galaxies generally host a mixture of components with
different exitation, composition, and kinematics. Derivation of emission line
ratios and kinematics could then be misleading, if due correction is not made
for the limited spatial and spectral resolutions of the observations. The aim
of this paper is to demonstrate, with application to a long slit spectrum of
the Seyfert2 galaxy NGC1358, how line intensities and velocities, together with
modelling and knowledge of the point spread function, may be used to resolve
the differing structures. In the situation outlined, the observed kinematics
differs for different spectral lines. From the observed intensity and velocity
distributions of a number of spectral lines and with some reasonable
assumptions to diminish the number of free parameters, the true line ratios and
velocity structures may be deduced. A preliminary solution for the nuclear
structure of NGC1358 is obtained, involving a nuclear point source and an
emerging outflow of high excitation with a post shock cloud, as well as a
nuclear emission line disk rotating in the potential of a stellar bulge and
expressing a radial exitation gradient. The method results in a likely scenario
for the nuclear structure of NGC1358. For definitive results an extrapolation
of the method to two dimensions combined with the use of integral field
spectroscopy will generally be necessary.Comment: to appear in proceedings for the IAU 277th Symposium, Editors: C.
Carignan, F. Combes, K. Freema
A remark on asymptotic completeness for the critical nonlinear Klein-Gordon equation
We give a short proof of asymptotic completeness and global existence for the
cubic Nonlinear Klein-Gordon equation in one dimension. Our approach to dealing
with the long range behavior of the asymptotic solution is by reducing it, in
hyperbolic coordinates to the study of an ODE. Similar arguments extend to
higher dimensions and other long range type nonlinear problems.Comment: To appear in Lett. Math. Phy
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