Journal Article

The Galactic Centre star S2 as a dynamical probe for intermediate-mass black holes

A. Gualandris, S. Gillessen and D. Merritt

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 409, issue 3, pages 1146-1154
Published in print December 2010 | ISSN: 0035-8711
Published online December 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17373.x
The Galactic Centre star S2 as a dynamical probe for intermediate-mass black holes

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We study the short-term effects of an intermediate-mass black hole (IBH) on the orbit of star S2 (S02), the shortest period star known to orbit the supermassive black hole (MBH) in the centre of the Milky Way. Near-infrared imaging and spectroscopic observations allow an accurate determination of the orbit of the star. Given S2’s short orbital period and large eccentricity, general relativity (GR) needs to be taken into account, and its effects are potentially measurable with current technology. We show that perturbations due to an IBH in orbit around the MBH can produce a shift in the apoapsis of S2 that is as large or even larger than the GR shift. An IBH will also induce changes in the plane of S2’s orbit at a level as large as 1° per period. We apply observational orbital fitting techniques to simulations of the S-cluster in the presence of an IBH and find that an IBH more massive than about 1000 M at the distance of the S-stars will be detectable at the next periapse passage of S2, which will occur in 2018.

Keywords: black hole physics; methods: numerical; stars: kinematics and dynamics; Galaxy: centre

Journal Article.  5699 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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