First Results of the Event Horizon Telescope

Abstract

The Event Horizon Telescope (EHT) collaboration has revealed the first-ever images of a black hole shadow at the heart of a giant elliptical galaxy Messier 87 (M87). The EHT links ground-based radio telescopes around the globe to form an Earth-sized virtual telescope with an unprecedented highest angular resolution using very long baseline interferometry (VLBI) at millimeter wavelengths. Images visually reveal the strongest evidence of an existence of a black hole in the universe. The bright compact radio source with a diameter of 42±3 micro-arcsecond (μas) suggests a supermassive black hole (SMBH) of (6.5±0.7)× 109 M⨀ (solar mass). An asymmetric ring-like morphology strongly suggests that we see gravitationally lensed emission from plasma rotating around the very vicinity of the SMBH event horizon. The image also supports the longstanding hypothesis that a SMBH powers an active galactic nucleus (AGN). The EHT collaboration demonstrates that VLBI at millimeter/sub-millimeter bands offers a powerful method to explorer gravity in its most extreme limit and at a previously inaccessible mass scale.