Self-force and fluid resonances

Abstract

The gravitational self-force acting on a particle orbiting a massive central body has thus far been computed for vacuum spacetimes involving a black hole. In this work we continue an ongoing effort to study the self-force in nonvacuum situations. We replace the black hole by a material body consisting of a perfect fluid, and determine the impact of the fluid's dynamics on the selfforce and resulting orbital evolution. We show that as the particle inspirals toward the fluid body, its gravitational perturbations trigger a number of quasinormal modes of the fluid-gravity system, which produce resonant features in the conservative and dissipative components of the self-force. As a proof-of-principle, we demonstrate this phenomenon in a simplified framework in which gravity is mediated by a scalar potential satisfying a wave equation in Minkowski spacetime.

Probing the nature of central objects in extreme-mass-ratio inspirals with gravitational waves

“…One of the effects that Ryan's formalism does not account for is matter tides. If the central object is not a black hole, its effect on the GW phasing can be nonnegligible [37,38]. Li et al [19] have included this effect in an extension of Ryan's formalism.…”

Modeling and detecting resonant tides of exotic compact objects

“…that often in these resonances there seems to be a large contribution from the asymmetric interference term in (III.23). It should be noted that although we have discussed a resonance in the radiated energy, there is also an interesting conservative resonant response in the backreaction on the orbit [69]. Moreover, once the full selfforce, including the conservative piece, is known for the black hole, it is evident that one can simply add to this the force associated to the (homogeneous) last term in (III.6), which requires no additional regularization [70].…”