Waveforms produced by a scalar point particle plunging into a Schwarzschild black hole: Excitation of quasinormal modes and quasibound states

摘要

With the possibility of testing massive gravity in the context of black holephysics in mind, we consider the radiation produced by a particle plunging fromslightly below the innermost stable circular orbit into a Schwarzschild blackhole. In order to circumvent the difficulties associated with black holeperturbation theory in massive gravity, we use a toy model in which we replacethe graviton field with a massive scalar field and consider a linear couplingbetween the particle and this field. We compute the waveform generated by theplunging particle and study its spectral content. This permits us to highlightand interpret some important effects occurring in the plunge regime which arenot present for massless fields such as (i) the decreasing and vanishing, asthe mass parameter increases, of the signal amplitude generated when theparticle moves on quasicircular orbits near the innermost stable circular orbitand (ii) in addition to the excitation of the quasinormal modes, the excitationof the quasibound states of the black hole.