Narayan, RameshGarcia, Michael R.McClintock, Jeffrey E.2019-09-221997Narayan, Ramesh, Michael R. Garcia, and Jeffrey E. McClintock. 1997. “Advection-Dominated Accretion and Black Hole Event Horizons.” The Astrophysical Journal 478 (2): L79–82. https://doi.org/10.1086/310554.0887-2783http://nrs.harvard.edu/urn-3:HUL.InstRepos:41384877The defining characteristic of a black hole is that it possesses an event horizon through which matter and energy can fall in but from which nothing escapes. Soft X-ray transients (SXTs), a class of X-ray binaries, appear to confirm this fundamental property of black holes. SXTs that are thought to contain accreting black holes display a large variation of luminosity between their bright and their faint states, while SXTs with accreting neutron stars have a smaller variation. This difference is predicted if the former stars have horizons, and the latter have normal surfaces.en-USJournal Article2019-09-2210.1086/310554