STU black holes and SgrA^⋆

Abstract

The equations of null geodesics in the STU family of rotating black hole solutions of supergravity theory, which may be considered as deformations of the vacuum Kerr metric, are completely integrable. We propose that they be used as a foil to test, for example, with what precision the gravitational field external to the black hole at the centre of our galaxy is given by the Kerr metric.By contrast with some metrics proposed in the literature, the STU metrics satisfy by construction the dominant and strong energy conditions. Our considerations may be extended to include the effects of a cosmological term. We show that these metrics permit a straightforward calculation of the properties of black hole shadows.

Explicit formulae for surface gravities in stationary circular axi-symmetric spacetimes

“…We emphasize that the canonical form deduced above is indeed sufficiently general to easily accommodate essentially all of the recently introduced quasi-phenomenological modifications of Kerr that have been the subject of so much recent scrutiny. See for instance [27][28][29][30][31][32][33][34][35][36][37][38][39][40] and [73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91].…”

Testing general relativity with the Event Horizon Telescope

“…If we allow for violation of the no-hair theorem, i.e., allow for the quadrupole moment of the spacetime to take arbitrary values, then the black-hole shadow becomes asymmetric and its size can take significantly larger or smaller values than what is given by equation (8). The outlines of black-hole shadows have since been calculated for a large number of metric that are either parametric extensions of the Kerr metric or solutions to non-GR field equations [98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118] (see, e.g., Fig. 8).…”

Supergravity Black Holes, Love Numbers and Harmonic Coordinates

“…With this in mind, we have previously studied the electrodynamics [8], the initial value problem [9], the photon sphere and sonic horizons [10], the equatorial timelike geodesics [11],…”