Hairy binary black holes in EinsteinMaxwelldilaton theory and their effectiveonebody description
Abstract
In general relativity and many modified theories of gravity, isolated black holes (BHs) cannot source massless scalar fields. EinsteinMaxwelldilaton (EMd) theory is an exception: through couplings both to electromagnetism and (nonminimally) to gravity, a massless scalar field can be generated by an electrically charged BH. In this work, we analytically model the dynamics of binaries comprised of such scalarcharged ("hairy") BHs. While BHs are not expected to have substantial electric charge within the standard model of particle physics, nearly extremally charged BHs could occur in models of minicharged dark matter and dark photons. We begin by studying the testbody limit for a binary BH in EMd theory, and we argue that only very compact binaries of nearly extremally charged BHs can manifest nonperturbative phenomena similar to those found in certain scalartensor theories. Then, we use the postNewtonian approximation to study the dynamics of binary BHs with arbitrary mass ratios. We derive the equations governing the conservative and dissipative sectors of the dynamics at nexttoleading order, use our results to compute the Fourierdomain gravitational waveform in the stationaryphase approximation, and compute the number of useful cycles measurable by the Advanced LIGO detector. Finally, we construct two effectiveonebody (EOB) Hamiltonians for binary BHs in EMd theory: one that reproduces the exact testbody limit and another whose construction more closely resembles similar models in general relativity, and thus could be more easily integrated into existing EOB waveform models used in the data analysis of gravitationalwave events by the LIGO and Virgo collaborations.
 Publication:

Physical Review D
 Pub Date:
 November 2018
 DOI:
 10.1103/PhysRevD.98.104010
 arXiv:
 arXiv:1809.03109
 Bibcode:
 2018PhRvD..98j4010K
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Theory
 EPrint:
 36 pages, 12 figures, updated to match published version