Apparent shape of super-spinning black holes

By Cosimo Bambi, K. Freese. 2008

242 citations recorded by the source corpus.

We consider the possibility that astrophysical black holes (BHs) can violate the Kerr bound; i.e., they can have angular momentum greater than BH mass, J>M. We discuss implications on the BH apparent shape. Even if the bound is violated by a small amount, the shadow cast by the BH changes significantly (it is {approx} an order of magnitude smaller) from the case with J{<=}M and can be used as a clear observational signature in the search for super-spinning BHs. We discuss briefly recent observations in the mm range of the supermassive BH at the center of the Galaxy, speculating on the possibility that it might violate the Kerr bound.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f4c5dc0c893c9b2e465d64d82f31d189da3443f4

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In Astronomy and Astrophysics

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Citations in the corpus

Testing the rotational nature of the supermassive object M87* from the circularity and size of its first image (2019, methodology): “(2,3) in [44]).”
TESTING THE NO-HAIR THEOREM WITH OBSERVATIONS IN THE ELECTROMAGNETIC SPECTRUM. II. BLACK HOLE IMAGES (2010, background): “Recently, Bambi & Freese (2009) explored the possibility of using blackhole images to test whether black holes violate the Kerr bound a ≤ M .”
Appearance of Keplerian discs orbiting Kerr superspinars (2010, background): “However, such solutions are not known at this time, and we follow the simplest possibility that is commonly used in most of the studies of the phenomena taking place in the field of Kerr superspinars [4, 5, 24].”
Constraining the spin and the deformation parameters from the black hole shadow (2014, background): “[37, 38], a number of tests has been proposed in the literature and shadows in different background metrics have been calculated by different groups [39–46].”
Black Hole Parameter Estimation from Its Shadow (2018, background): “The shadows of modified theory black holes are smaller and more distorted when compared with the Kerr black hole shadow (Bambi & Freese 2009; Johannsen & Psaltis 2010; Falcke & Markoff 2013; Broderick et al. 2014; Younsi et al. 2016; Giddings & Psaltis 2018; Mizuno et al. 2018; Breton et al. 2019;…”
A coordinate-independent characterization of a black hole shadow (2015, methodology): “A way to measure this deformation was first suggested by Hioki & Maeda (2009) and then further developed by other authors (Bambi & Freese 2009; Bambi & Yoshida 2010; Bambi & Modesto 2013).”
Imaging a boson star at the Galactic center (2015, background): “Many articles have investigated whether alternative compact objects exhibit differences with respect to Kerr predictions (Bambi & Freese 2009; Johannsen & Psaltis 2010; Amarilla et al. 2010; Amarilla & Eiroa 2013; Vincent 2014; Moffat 2015; Cunha et al. 2015).”