2018/03/31 by Fiona McCarthy, David Kubiznak, Robert B. Mann
Physics and Astronomy · #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.97.104025
published as Phys. Rev. D 97, 104025 (2018) · 7 pages, 5 figures. v2: some small changes and corrections
arxiv created 2018/05/21 · arxiv updated 2018/05/23
By employing the moduli space approximation, we analytically calculate the gravitational wave signatures emitted upon the merger of two extremally charged dilatonic black holes. We probe several values of the dilatonic coupling constant a, and find significant departures from the Einstein--Maxwell (a=0) counterpart studied in arXiv:1704.08520. For (low energy) string theory black holes (a=1) there are no coalescence orbits and only a memory effect is observed, whereas for an intermediate value of the coupling (a=1/√(3)) the late-time merger signature becomes exponentially suppressed, compared to the polynomial decay in the a=0 case without a dilaton. Such an imprint is in principle observable and could reveal the presence of a scalar field (as for example predicted by string theory) in black hole mergers.