A Tale of Two Jets

TL;DR

This paper reviews recent simulations demonstrating how merging non-spinning black holes in a magnetic field can generate dual jets, which transition into a single jet post-merger, shedding light on jet formation mechanisms.

Contribution

It introduces novel simulation results showing jet formation from non-spinning black hole mergers in a force-free magnetic environment.

Findings

Black holes act as magnetic field stirrers during inspiral.

Jets form around each black hole before merging.

Dual jets transition into a single jet after merger.

Abstract

One of the most interesting high-energy, astrophysical phenomena are relativistic jets emitted from highly localized sky location. Such jets are common in Nature, observed to high redshift and in a range of wavelengths. Their precise generation mechanism remains a bit of a mystery, but they are generically believed to be powered by black holes. We here summarize the recent simulations of Palenzuela, Lehner and Liebling that shed light on the jet generation mechanism. These authors studied the merger of two non-spinning black holes in the presence of a magnetic field, perpendicular to the orbital plane and anchored by a circumbinary accretion disk, in the "force-free" approximation. They found that each black hole essentially acts as a "straw" that stirs the magnetic field lines around the center of mass as the black holes inspiral. The twisting of the magnetic field lines then generates jets around each black hole, even though these are not spinning. Their simulations show the formation of such a dual jet geometry and how it transitions to a single jet one, as the black holes merge due to gravitational wave emission.