20,768 research outputs found
Holographic description of three dimensional Godel black hole
Three dimensional G\"{o}del black hole is a solution to
Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant. We
have studied the hidden conformal symmetry for massive scalar field without any
additional condition in the background of three dimensional non-extremal and
extremal G\"{o}del black holes. This conformal symmetry is uncovered by the
observation that the radial wave equations in both cases can all be rewritten
in the form of Casimir operators through introducing two sets of
conformal coordinates to write the generators. At last, we give the
holographic dual descriptions of Bekenstein-Hawking entropies of non-extremal
and extremal black holes from Cardy formula of conformal field theory.Comment: 7 pages, no figur
Superradiant instability of the charged scalar field in stringy black hole mirror system
It has been shown that the mass of the scalar field in the charged stringy
black hole is never able to generate a potential well outside the event horizon
to trap the superradiant modes. This is to say that the charged stringy black
hole is stable against the massive charged scalar perturbation. In this paper
we will study the superradiant instability of the massless scalar field in the
background of charged stringy black hole due to a mirror-like boundary
condition. The analytical expression of the unstable superradiant modes is
derived by using the asymptotic matching method. It is also pointed out that
the black hole mirror system becomes extremely unstable for a large charge
of scalar field and the small mirror radius .Comment: 5 pages, no figure, published versio
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