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Gravitational radiation from collisions at the speed of light: a massless particle falling into a Schwarzschild black hole

Vitor Cardoso·Jose' P. S. Lemos
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Abstract

We compute spectra, waveforms, angular distribution and total gravitational energy of the gravitiational radiation emitted during the radial infall of a massless particle into a Schwarzschild black hole. Our fully relativistic approach shows that (i) less than 50% of the total energy radiated to infinity is carried by quadrupole waves, (ii) the spectra is flat, and (iii) the zero frequency limit agrees extremely well with a prediction by Smarr. This process may be looked at as the limiting case of collisions between massive particles traveling at nearly the speed of light, by identifying the energy $E$ of the massless particle with $m_0 γ$, $m_0$ being the mass of the test particle and $γ$ the Lorentz boost parameter. We comment on the implications for the two black hole collision at nearly the speed of light process, where we obtain a 13.3% wave generation efficiency, and compare our results with previous results by D'Eath and Payne.

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Vitor Cardoso, Jose' P. S. Lemos. 2002-06-15. Gravitational radiation from collisions at the speed of light: a massless particle falling into a Schwarzschild black hole. https://doi.org/10.1016/s0370-2693(02)01961-5

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