STRW local: Colloquia


The Chaotic Origins of LIGO's Binary Black Holes

Date: 14-03-2019
Time: 11:00 h
Author: Nick Stone

Over the next several years, Advanced LIGO and Virgo are expected to discover hundreds of gravitational wave (GW) signals from merging black hole binaries (BBHs). These GWs will offer unprecedented tests of strong-field and dynamical gravity, but for astrophysicists, the most basic questions about them remain unanswered. What astrophysical process is responsible for producing large numbers of BBHs with separations close enough to merge within a Hubble time? At the present moment, roughly half a dozen such formation channels have been proposed, and it is unclear which, if any, predominate in nature. I will quickly review the primary BBH formation scenarios that appear compatible with current LIGO observations, and then present my own recent work on this problem. First, I will describe the novel “AGN channel” we have developed, wherein wide BBH binaries that form or are trapped in AGN accretion disk are quickly driven to merge by hydrodynamic torques. Second, I will present our recently derived statistical solution to the non-hierarchical 3-body problem. While this solution may be useful in a number of different astrophysical systems, I will discuss its implications for BBH dynamical formation scenarios, which typically involve iterated 3-body scatterings.