ELFT HÍRADÓ

[Bence Kocsis <bkocsis AT caesar.elte.hu>]

*ELTE Astrophysics Seminar *

Tuesday, June 11, 16:00,
ELTE Pazmany Peter setany 1/A, room 3.139

*Resonant relaxation of stars around a supermassive black hole*

*   Jean-Baptiste Fouvry* (Institute for Advanced Study, Princeton)

In the vicinity of a supermassive black hole, stars move on nearly
Keplerian orbits. Yet, because of the enclosed stellar mass and general
relativity, the potential slightly deviates from the Keplerian one, which
causes the stellar orbits to precess. Similarly, as a result of the finite
number of stars, the mutual gravitational torques between pairs of stars
also drive a rapid reorientation of the stars' orbital orientation, much
faster than the standard two-body relaxation driven by local scatterings.
Overall, the combination of these two effects leads to a stochastic
evolution of stellar orbital angular momentum vectors, through a process
named "resonant relaxation". Owing to recent developments in the diffusion
theory of long-range interacting systems, I will show how one can fully
describe such dynamics, in particular scalar resonant relaxation
(relaxation of the norm of the angular momentum) and vector resonant
relaxation (relaxation of the direction of the angular momentum vector). I
will also highlight some astrophysical applications of these new methods,
for example to understand the inefficiency of resonant relaxation to induce
stellar tidal disruptions.

Everyone is welcome!