Gravity seminar: Small-mass-ratio binaries and second-order perturbation theory – Adam Pound (University of Southampton)

Extreme-mass-ratio inspirals (EMRIs) will be key sources for LISA, with a unique science yield that includes unparalleled tests of the Kerr nature of massive black holes. However, this science yield depends on waveform templates that maintain phase accuracy over the course of ~10^5 orbits. In this talk, I describe the ongoing efforts to model EMRIs using self-force theory, a perturbative expansion in powers of the system’s small mass ratio. I focus on current work to calculate effects at second order in the mass ratio, which will be essential for accurate models. I discuss recent results for the energy flux at second perturbative order, which offer strong evidence that perturbative self-force models will be highly accurate not just for EMRIs but also for intermediate-mass-ratio inspirals and possibly even for mass ratios in the range of 1:10 — 1:50.