Black Hole Mergers in Field Triple Systems

Kedron Silsbee (Princeton) - November 14, 2016 at 12:10 pm

The recent observations by LIGO of merging black holes have spurred research into possible mechanisms to cause binary black hole mergers. Most of these fall into two classes - those involving evolution of an isolated binary, and those involving dynamical interactions in a cluster of stars. In this talk, I will discuss the possibility of black hole mergers in isolated field triple systems where the inner binary contains two black holes. In this scenario, the outer companion excites Lidov-Kozai oscillations in the inner binary, causing it to undergo close pericenter passages. During a sufficiently close pericenter passage, gravitational radiation shrinks the inner orbit so that the black holes will merge due to gravitational radiation in less time than it takes the companion to torque it out of alignment. I will argue based on simulations that in the absence of large natal kicks, the rate for this mechanism is likely several per cubic gigaparsec per year - on the low end of the total binary black hole merger rate estimated from the current LIGO results. I will also discuss some observational signatures of black hole mergers formed in this way - notably the possibility of inspirals that will be dramatically non-circular while emitting in the LIGO band.

The seminar will be held in 131A Campbell Hall.

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