Effect of massive perturbers on extreme mass-ratio inspiral waveforms

Abstract

Extreme mass ratio inspirals, in which a stellar-mass object orbits a supermassive black hole, are prime sources for space-based gravitational wave detectors because they will facilitate tests of strong gravity and probe the spacetime around rotating compact objects. In the last few years of such inspirals, the total phase is in the millions of radians and details of the waveforms are sensitive to small perturbations. We show that one potentially detectable perturbation is the presence of a second supermassive black hole within a few tenths of a parsec. The acceleration produced by the perturber on the extreme mass-ratio system produces a steady drift that causes the waveform to deviate systematically from that of an isolated system. If the perturber is a few tenths of a parsec from the extreme-mass ratio system (plausible in as many as a few percent of cases) higher derivatives of motion might also be detectable. In that case, the mass and distance of the perturber can be derived independently, which would allow a new probe of merger dynamics.

Low-frequency gravitational-wave science with eLISA/NGO

“…EMRIs are expected to be very clean astrophysical systems, except perhaps in few systems with strong interactions with the accretion disk [174][175][176], or with perturbations due to a second nearby MBH or star [177,178]. Over day-long timescales, EMRI orbits are essentially geodesics of the background geometry; on longer timescales, the loss of energy and angular momentum to GWs causes a slow change of the geodesic parameters.…”

Can We Probe Planckian Corrections at the Horizon Scale with Gravitational Waves?

“…in vacuum), but supermassive compact object binaries may have a circumbinary accretion disk, or they may be perturbed by a third body. The presence of such effects could impact the GW signal [40][41][42][43] and, the use of vacuum waveforms to fit this signal could incorrectly lead to non-zero measurements of Love numbers, which could be in turn incorrectly associated with ECOs. Mismodeling error [44] is a form of systematic uncertainty that becomes more severe for high signal-to-noise ratio events and must thus be included in the total error budget, which could further limit inferences made about ECOs from Love number measurements.…”

Gravitational wave tests of strong field general relativity with binary inspirals: Realistic injections and optimal model selection

“…For instance, the presence of accretion disks [39,40], the presence of a third companion [41], the unknown effects of the neutron star equations of state [42,43], etc. To illustrate how these types of effects can hinder our ability to test the nature of gravity, in Figure 7 we have plotted the Bayes factors between a b = −3 ppE model and GR applied to critical ppE injections.…”