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 hvssurvey.tex ApJ, 2009, 290, 1639
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% arXiv:0808.2469

\documentclass[12pt,preprint]{aastex}
\begin{document}

\title{ MMT Hypervelocity Star Survey }

\author{Warren R.\ Brown,
	Margaret J.\ Geller,
	Scott J.\ Kenyon}

\affil{Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA 02138}
\email{wbrown@cfa.harvard.edu, mgeller@cfa.harvard.edu, skenyon@cfa.harvard.edu}

\begin{abstract}

	We describe a new survey for unbound hypervelocity stars (HVSs), stars
traveling with such extreme velocities that dynamical ejection from a massive black
hole is their most likely origin.
	We investigate the possible contribution of unbound runaway stars, and show
that the physical properties of binaries constrain low mass runaways to bound
velocities.
	We measure radial velocities for HVS candidates with the colors of
early A-type and late B-type stars.
	We report the discovery of 6 unbound HVSs with velocities and distances
exceeding the conservative escape velocity estimate of Kenyon and collaborators.
We additionally report 4 possibly unbound HVSs with velocities and distances
exceeding the lower escape velocity estimate of Xue and collaborators.  These
discoveries increase the number of unbound HVSs by 60\% - 100\%.
	Other survey objects include 19 newly identified $z\sim2.4$ quasars.
	One of the HVSs may be a horizontal branch star, consistent with the number
of evolved HVSs predicted by Galactic center ejection models.  Finding more evolved
HVSs will one day allow a probe of the low-mass regime of HVSs and will constrain
the mass function of stars in the Galactic center.

\end{abstract}

\end{document}