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

Ann-Marie Madigan, Yuri Levin and Clovis Hopman

Paper: ApJL, submitted

EPrint Server: 0812.3395


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. We show that the dynamical evolution of such a disk results in several of its stars acquiring high (1-e\ll 0.1) orbital eccentricity. Binary stars on such highly eccentric orbits would get tidally disrupted by the SgrA* black hole, possibly producing both S-stars near the black hole and high-velocity stars in the Galactic halo.

Preprints available from the authors at annmarie.madigan@gmail.com , or the raw TeX (no figures) if you click here.

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