# fizinfo AT lists.kfki.hu

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**From**: Bence Kocsis <bkocsis AT gmail.com>**To**: fizinfo AT lists.kfki.hu, kutatok AT konkoly.hu, astrophysics AT listbox.elte.hu**Subject**: [Fizinfo] ELTE Astrophysics Seminar**Date**: Fri, 7 Jun 2019 10:45:58 +0200**Authentication-results**: smtp0.kfki.hu (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com

*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!

**[Fizinfo] ELTE Astrophysics Seminar**,*Bence Kocsis, 06/07/2019*- <Possible follow-up(s)>
**[Fizinfo] ELTE Astrophysics Seminar**,*Bence Kocsis, 06/07/2019*

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