Gravitational waves from a spinning particle plunging into a Kerr black hole

Motoyuki Saijo, Keiichi Maeda, Masaru Shibata, Yasushi Min

Research output: Contribution to journalArticle

40 Citations (Scopus)


Using a black hole (BH) perturbation approach, we numerically study gravitational waves from a spinning particle of mass μ and spin s on the equatorial plane plunging into a Kerr BH of mass M and spin a. When we take into account the particle spin s, (a) the motion of the particle changes due to the coupling effects between s and the orbital angular momentum Lz and between s and a, and also (b) the energy momentum tensor of the linearized Einstein equations changes. We calculate the total radiated energy, linear momentum, angular momentum, the energy spectrum, and waveform of gravitational waves, and we find the following feauires. (1) There are three spin coupling effects: between Lz and a, between s and Lz, and between s and a when s is considered. Among them, (Lz·a) coupling is the most important effect for the amount of gravitational radiation, and the other two effects are not as remarkable as the first one. However, these effects are still important; for example, the total radiated energy changes by a factor of ∼2 for the case of a/M = 0.6. Lz/μM = 1.5 if we change s from 0 to ≲M. (2) For the case when one of the three spins (a, Lz, and s) is vanishing the amount of gravitational radiation becomes larger (smaller) if spin axes of the other two are parallel (antiparallel). For the case when three spins are nonvanishing, the amount of gravitational radiation becomes maximum if all the axial directions of s, a, and Lz coincide. Thus, our calculations indicate that in a coalescence of two black holes (BHs) whose spins and orbital angular momentum are aligned, gravitational waves are emitted most efficiently.

Original languageEnglish
Article number064005
Pages (from-to)640051-6400520
Number of pages5760470
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number6
Publication statusPublished - 1998 Sep 15


ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Nuclear and High Energy Physics
  • Mathematical Physics
  • Physics and Astronomy (miscellaneous)

Cite this