2002/07/12 by Marek A. Abramowicz, M. A. Abramowicz, W. Kluźniak +3 · 237 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Black hole (networking) #Charged black hole #Computer science #Event horizon #Extremal black hole #Fuzzball #General relativity #Hawking radiation #Horizon #Nonsingular black hole models #Physics #Pulsars and Gravitational Waves Research #Quantum mechanics #Schwarzschild metric #Schwarzschild radius #Spacetime #Theoretical physics #White hole #astro-ph
paper · pdf · doi:10.1051/0004-6361:20021645
published in Astronomy and Astrophysics 396(3), L31-L34 (EDP Sciences) · 4 pages, no figures, submitted to A&A Letters
arxiv created 2002/07/12 · openalex publication_date 2002/12/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Recently, several ways of verifying the existence of black-hole horizons have been proposed. We show here that most of these suggestions are irrelevant to the problem of the horizon, at best they can rule out the presence of conventional baryonic matter in the outer layers of black-hole candidates. More generally, we argue that it is fundamentally impossible to detect in electromagnetic radiation direct evidence for the presence of a black-hole horizon. This applies also to future observations, which would trace very accurately the details of the space-time metric of a body suspected of being a black hole. Specific solutions of Einsteins's equations lack an event horizon, and yet are indistinguishable in their electromagnetic signature from Schwarzschild black holes.