9,575 research outputs found
Signature of the Van der Waals like small-large charged AdS black hole phase transition in quasinormal modes
We calculate the quasinormal modes of massless scalar perturbations around
small and large four-dimensional Reissner-Nordstrom-Anti de Sitter (RN-AdS)
black holes. We find a dramatic change in the slopes of quasinormal frequencies
in small and large black holes near the critical point where the Van der Waals
like thermodynamic phase transition happens. This further supports that the
quasinormal mode can be a dynamic probe of the thermodynamic phase transition.Comment: 20 pages,11 figures.The new version is accepted for publication in
JHE
Charged Scalar Perturbations around Garfinkle-Horowitz-Strominger Black Holes
We examine the stability of the Garfinkle-Horowitz-Strominger (GHS) black
hole under charged scalar perturbations. We find that different from the
neutral scalar field perturbations, only two numerical methods, such as the
continued fraction method and the asymptotic iteration method, can keep high
efficiency and accuracy requirements in the frequency domain computations. The
comparisons of the efficiency between these two methods have also been done.
Employing the appropriate numerical method, we show that the GHS black hole is
always stable against charged scalar perturbations. This is different from the
result obtained in the de Sitter and Anti-de Sitter black holes. Furthermore we
argue that in the GHS black hole background there is no amplification of the
incident charged scalar wave to cause the superradiance, so that the
superradiant instability cannot exist in this spacetime.Comment: 24 pages, 5 figure
Superradiant instability of Kerr-de Sitter black holes in scalar-tensor theory
We investigate in detail the mechanism of superradiance to render the
instability of Kerr-de Sitter black holes in scalar-tensor gravity. Our results
provide more clues to examine the scalar-tensor gravity in the astrophysical
black holes in the universe with cosmological constant. We also discuss the
spontaneous scalarization in the de Sitter background and find that this
instability can also happen in the spherical de Sitter configuration in a
special style.Comment: (v2)21 pages, 21 figures; Sec. V revised; This version has been
accepted for publication by JHE
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