title: Rapid formation of supermassive black hole binaries in galaxy mergers with gas.
abstract: Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of galaxies. It is normally assumed that after the merger of two massive galaxies, a SMBH binary will form, shrink because of stellar or gas dynamical processes, and ultimately coalesce by emitting a burst of gravitational waves. However, so far it has not been possible to show how two SMBHs bind during a galaxy merger with gas because of the difficulty of modeling a wide range of spatial scales. Here we report hydrodynamical simulations that track the formation of a SMBH binary down to scales of a few light years after the collision between two spiral galaxies. A massive, turbulent, nuclear gaseous disk arises as a result of the galaxy merger. The black holes form an eccentric binary in the disk in less than 1 million years as a result of the gravitational drag from the gas rather than from the stars.
authors.affiliation: Institute for Theoretical Physics, University of Zurich, Winterthurestrasse 190, CH-8057 Zürich, Switzerland. lucio@phys.ethz.ch
authors.forename: L
authors.initials: L
authors.lastname: Mayer
authors.forename: S
authors.initials: S
authors.lastname: Kazantzidis
authors.forename: P
authors.initials: P
authors.lastname: Madau
authors.forename: M
authors.initials: M
authors.lastname: Colpi
authors.forename: T
authors.initials: T
authors.lastname: Quinn
authors.forename: J
authors.initials: J
authors.lastname: Wadsley