In this article, the behaviour of a charged and massive scalar field around a
global monopole swallowed by a Reissner-Nordstr\"{o}m-Anti-de Sitter (RN-AdS)
black hole is investigated by considering the Klein-Gordon equation in this
geometry. The superradiance phenomenon and instability behaviour of the black
hole against charged scalar perturbations are studied for both an RN-AdS case
and also for an RN black hole surrounded by a reflective mirror, i.e., the
black hole bomb case. The effects of the monopole on these cases are discussed
analytically and also with the help of several graphs in detail. The monopole
charge affects the superradiance threshold frequency and also effects the
instability time scale for both cases. The existence of global monopole makes
these black holes more stable against superradiance instability.Comment: V3: 19 pages, 3 figures, references added, introduction is extended,
Revtex, Published versio
