http://arxiv.org/abs/1808.02905
We show that gravitational floating orbits may exist for black holes with rotating hairs. These black hole hairs could originate from the superradiant growth of a light axion field around the rotating black hole. If a test particle rotates around the black hole, its tidal field may trigger the dynamical transition between a co-rotating state and a counter-rotating state of the axion cloud, and the dissipation of the counter-rotating cloud state feeds angular momentum back to the test particle. Following this mechanism, an extreme-mass-ratio-inspiral (EMRI) system, as a source for LISA, may face delayed merger as the EMRI orbit stalls by the tidal response of the cloud, until the cloud being almost fully dissipated. If the cloud dissipation timescale is longer than the average separation between EMRI mergers, it may lead to interesting interaction between multiple EMRI objects at comparable radii.
J. Zhang and H. Yang
Fri, 10 Aug 18
43/45
Comments: 6 pages, 4 figures
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