## From Gravitational Atoms to EMRI: Baby Steps

#### by Ofri Telem

*Hebrew University*

##### at Particles and Fields Seminar

Mon, 15 May 2023, 14:10

Sacta-Rashi Building for Physics (54), room 207

#### Abstract

The accurate calculation of Extreme-Mass-Ratio Black-Hole inspirals is a formidable multiscale problem. It is of fundamental importance to the analysis of gravitational wave-forms in the future space-based gravitational wave detector LISA. While numerical-relativity is prohibitive due to run-time overheads, the efficient line of attack on this problem is called the Self-Force, or Post-Adiabatic expansion. It is essentially perturbation theory in the back-reaction of the emitted gravitational radiation on the trajectory of the inspiraling Black Hole.

In this talk we present a new concept for the calculation of EMRI, and report on two baby steps on the way to realize it as a full post-adiabatic calculation - our holy grail. Our proposed line-of-attack on the problem is to consider it as the classical limit of a "quantum" Gravitational Atom. One constructs an equivalent quantum system in which the small black hole is not a pointlike object - instead, it cascades between (gravitational) orbitals, spontaneously emitting gravitational radiation. This has the effect of regulating (in fact renormalizing) the classical problem. The true gravitational wave signal is then recovered from the classical limit of the quantum computation.

The presented baby steps on the way to this ambitious program are

1. Reproducing flyby Schwarschild and Kerr geodesics from quantum scattering

2. Reproducing the electromagnetic self-force from spontaneous emission

These proofs-of-principle provide significant encouragement to our proposal, as they demonstrate that the quantum approach can reproduce (1) motion in curved space (2) radiation reaction.

Created on 10-05-2023 by Kats, Yevgeny (katsye)

Updaded on 10-05-2023 by Kats, Yevgeny (katsye)