------------------------------------------------------------------------ ecc_instability.tex ApJL, submitted MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_35795_3728400.1229695439892" X-Google-Sender-Auth: 7edf80480dc23626 X-MailScanner-Information: Please contact the postmaster@aoc.nrao.edu for more information X-MailScanner: Found to be clean X-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=0.001, required 5, autolearn=disabled, HTML_MESSAGE 0.00) X-MailScanner-From: annmarie.madigan@gmail.com X-Spam-Status: No ------=_Part_35795_3728400.1229695439892 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline %astro-ph/0812.3395 \documentclass[english]{emulateapj} \begin{document} \title{A New Secular Instability of Eccentric Stellar Disks Around Supermassive Black Holes, \\ with Application to the Galactic center} \author{Ann-Marie Madigan, Yuri Levin and Clovis Hopman} \affiliation{Leiden University, Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden} \email{madigan@strw.leidenuniv.nl } \begin{abstract} 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. \end{abstract} \end{document} -- Ann-Marie Madigan Sterrewacht Leiden PO Box 9513 2300 RA Leiden The Netherlands phone +31-(0)71-527-5812 ------=_Part_35795_3728400.1229695439892 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline %astro-ph/0812.3395

\documentclass[english]{emulateapj}
\begin{document}

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

\author{Ann-Marie Madigan, Yuri Levin and Clovis Hopman}

\affiliation{Leiden University, Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden}

\email{madigan@strw.leidenuniv.nl}

\begin{abstract}
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.

\end{abstract}
\end{document}










--
Ann-Marie Madigan

Sterrewacht Leiden
PO Box 9513
2300 RA Leiden
The Netherlands
phone +31-(0)71-527-5812
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