330 research outputs found
Decay of a charged scalar and Dirac fields in the Kerr-Newman-de Sitter background
We find the quasinormal modes of the charged scalar and Dirac fields in the
background of the rotating charged black holes, described by the Kerr-Newman-de
Sitter solution. The dependence of the quasinormal spectrum upon the black hole
parameters mass M, angular momentum a, charge Q, as well as on values of the
\Lambda-term and field charge q is investigated. Special attention is given to
the near extremal limit of the black hole charge. In particular, we find that
for both scalar and Dirac fields, charged perturbations decay quicker for q>0
and slower for q<0 for values of black holes charge Q less than than some
threshold value, which is close to the extremal value of charge and depend on
parameters of the black holes.Comment: Phys. Rev. D, in pres
How to tell the shape of a wormhole by its quasinormal modes
Here we shall show how to reconstruct the shape function of a spherically
symmetric traversable Lorenzian wormhole near its throat if one knows high
frequency quasinormal modes of the wormhole. The wormhole spacetime is given by
the Morris-Thorne ansatz. The solution to the inverse problem via fitting of
the parameters within the WKB approach is unique for arbitrary tideless
wormholes and some wormholes with non-zero tidal effects, but this is not so
for arbitrary wormholes. As examples, we reproduce the near throat geometries
of the Bronnikov-Ellis and tideless Morris-Thorne metrics by their quasinormal
modes at high multipole numbers .Comment: 8 pages, revtex4, 1 figure; version accepted for publication in
Physics Letters
Quasinormal modes of the charged black hole in Gauss-Bonnet gravity
The d-dimensional string generated gravity models lead to Einstein-Maxwell
equations with quadratic order correction term called the Gauss-Bonnet term. We
calculate the quasinormal modes for the d-dimensional charged black hole in the
framework of this model. The quasinormal spectrum essentially depends upon the
Gauss-Bonnet coupling parameter which is related to the string scale,
and is totally different from that for black holes derived from Einstein
action. In particular, at large the quasinormal modes are proportional
to , while as goes to zero the qusinormal modes approach their
Schwarzschild values. In contrary to Einstein theory black hole behavior, the
damping rate of the charged GB black hole as a function of charge does not
contain a chracteristic maximum, but instead the monotonic falling down is
observed. In addition, there have been obtained an asymptotic formula for large
multipole numbers.Comment: 16 pages, 4 figures, 3 tables; misprints correcte
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