University of Birmingham > Talks@bham > Astrophysics Seminars > The dynamics of supermassive binary black hole immersed in an accretion disc on a retrograde orbit

The dynamics of supermassive binary black hole immersed in an accretion disc on a retrograde orbit

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In this talk I would like to discuss a non-standard type of migration of a perturbing body (secondary) embedded in an accretion disc around some more massive object (primary), when its orbital motion is opposite to that of the disc gas. This may have relevance to supermassive black hole binaries immersed in an accretion disc, where both prograde and retrograde orbits have been proposed. Such a situation can also be possible in certain protoplanetary systems when, say, the direction of orbital motion of a certain planet is reversed by gravitational interactions with other planets.

In my talk, both analytic methods and two dimensional hydrodynamical simulations will be discussed, focusing on the case where the binary mass ratio is small but large enough to significantly perturb the disk. I’ll address the issues of different migration regimes, associated evolution timescales, a gap opening criterion and a modification of the disk’s structure due to the presence of the secondary. It will be shown that when the orbital evolution is caused by interaction with the disc the accretion rate on to the secondary is of the order of $q^{1/3}$ of that to the primary, where $q$ is the mass ratio. The accretion rate can, however, be amplified significantly when the orbital evolution is accelerated by the emission of gravitational waves. This could potentially lead to interesting observational consequences.

This talk is part of the Astrophysics Seminars series.

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