https://doi.org/10.1140/epjc/s10052-014-3051-8
Regular Article - Theoretical Physics
Superradiant instability of charged scalar field in stringy black hole mirror system
Department of Physics, Henan Normal University, Xinxiang, 453007, China
* e-mail: liran.gm.1983@gmail.com
Received:
30
March
2014
Accepted:
1
September
2014
Published online:
27
September
2014
It has been shown that the mass of a charged scalar field in the background of a 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 massive charged scalar perturbations. 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 frequencies of 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 the scalar field and a small mirror radius 
.
© SIF and Springer-Verlag Berlin Heidelberg, 2014
