Broderick, Avery E.Narayan, Ramesh2019-09-222007Broderick, Avery E, and Ramesh Narayan. 2007. “Where Are All the Gravastars? Limits upon the Gravastar Model from Accreting Black Holes.” Classical and Quantum Gravity 24 (3): 659–66. https://doi.org/10.1088/0264-9381/24/3/009.0264-93811361-6382http://nrs.harvard.edu/urn-3:HUL.InstRepos:41384931The gravastar model, which postulates a strongly correlated thin shell of anisotropic matter surrounding a region of anti-de Sitter space, has been proposed as an alternative to black holes. We discuss constraints that presentday observations of well-known black hole candidates place on this model. We focus upon two black hole candidates known to have extraordinarily low luminosities: the supermassive black hole in the galactic centre, Sagittarius A*, and the stellar-mass black hole, XTE J1118 + 480. We find that the length scale for modifications of the type discussed in Chapline et al (2003 Int. J. Mod. Phys. 18 3587 - 90) must be sub-Planckian.en-USJournal Article2019-09-2210.1088/0264-9381/24/3/009