A note on the observational evidence for the existence of event horizons in astrophysical black hole candidates

Abstract

Black holes have the peculiar and intriguing property of having an event horizon, a one-way membrane causally separating their internal region from the rest of the Universe. Today astrophysical observations provide some evidence for the existence of event horizons in astrophysical black hole candidates. In this short paper, I compare the constraint we can infer from the non-observation of electromagnetic radiation from the putative surface of these objects with the bound coming from the ergoregion instability, pointing out the respective assumptions and limitations.

4 pages, no figures. v2: some typos corrected

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Cited by in corpus (11)

• Testing black hole candidates with electromagnetic radiation
• Constraining the spin and the deformation parameters from the black hole shadow
• Measuring the Kerr spin parameter of regular black holes from their shadow
• No-Hair Theorem in the Wake of Event Horizon Telescope
• Einstein-Æther Gravity in the light of Event Horizon Telescope Observations of M87*
• K$\alpha$ iron line profile from accretion disks around regular and singular exotic compact objects
• Measuring the Kerr spin parameter of a non-Kerr compact object with the continuum-fitting and the iron line methods
• Testing the Kerr Nature of Black Hole Candidates using Iron Line Spectra in the CPR Framework
• On an alternative mechanism for the black hole echoes
• Testing the nature of the supermassive black hole candidate in SgrA* with light curves and images of hot spots
• Scattering of particles by deformed non-rotating black holes