A New Secular Instability of Eccentric Stellar Disks Around Supermassive Black Holes, with Application to the Galactic Center

Understand

We identify a new secular instability of eccentric stellar disks around supermassive black holes.

• We show that retrograde precession of the stellar orbits, due to the presence of a stellar cusp, induces coherent torques that amplify deviations of individual orbital eccentricities from the average, and thus drive all eccentricities away from their initial value.
• We investigate the instability using N-body simulations, and show that it can drive individual orbital eccentricities to significantly higher or lower values on the order of a precession time-scale.
• This physics is relevant for the Galactic center, where massive stars are likely to form in eccentric disks around the SgrA* black hole.