Speakers
Description
It has been shown that spherical orbits around Kerr black holes remain
spherical (zero eccentricity) under the influence of gravitational
radiation reaction in the adiabatic limit. I will show that spherical
orbits in non-Kerr black holes that still preserve most of the good
qualities and symmetries of Kerr spacetime can access certain resonances
in such a way that an initially spherical inspiral acquires nonzero
eccentricity and becomes nonspherical. The strength of resonant excitation
of eccentricity depends on the initial position and inclination of the
integrable EMRI system. The harmonics of gravitational waves emitted from
these inspirals undergo a frequency modulation as the orbit
“metamorphoses” from spherical to nonspherical, due to the effect of
resonant eccentricity excitation. The gain that low-amplitude harmonics
experience in these oligochromatic EMRIs, due to resonances, may be
detectable with future spaceborne detectors and serves as an indicator of
non-Kerrness of the background spacetime.
