Title:	Deformation of the Galactic Centre stellar cusp due to the gravity of a growing gas disc
Authors:	Kaur, Karamveer Sridhar, S.
Issue Date:	11-Jun-2018
Publisher:	Oxford University Press on behalf of the Royal Astronomical Society
Citation:	Monthly Notices of the Royal Astronomical Society, 2018, Vol. 477; p112-126
Abstract:	The nuclear star cluster surrounding the massive black hole at the Galactic Centre consists of young and old stars, with most of the stellar mass in an extended, cuspy distribution of old stars. The compact cluster of young stars was probably born in situ in a massive accretion disc around the black hole. We investigate the effect of the growing gravity of the disc on the orbits of the old stars, using an integrable model of the deformation of a spherical star cluster with anisotropic velocity dispersions. A formula for the perturbed phase-space distribution function is derived using linear theory, and new density and surface density profiles are computed. The cusp undergoes a spheroidal deformation with the flattening increasing strongly at smaller distances from the black hole; the intrinsic axis ratio ∼0.8 at ∼0.15 pc. Stellar orbits are deformed such that they spend more time near the disc plane and sample the dense inner parts of the disc; this could result in enhanced stripping of the envelopes of red giant stars. Linear theory accounts only for orbits whose apsides circulate. The non-linear theory of adiabatic capture into resonance is needed to understand orbits whose apsides librate. The mechanism is a generic dynamical process, and it may be common in galactic nuclei.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/6885
ISSN:	0035-8711 1365-2966 - (online
Alternative Location:	http://adsabs.harvard.edu/abs/2018MNRAS.477..112K https://arxiv.org/abs/1709.04263 https://doi.org/10.1093/mnras/sty612
Copyright:	The Author(s)
Appears in Collections:	Research Papers (A&A)

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