Description acceptable. This result was achieved with the most notable use of Katie Bouman et al.’s CHIRP algorithm for deconvolution. For 10 points each:
[10m] Describe this 2019 result achieved by processing EHT radio wave observations. This result was published in the fourth of a series of six papers whose fifth entry describes its “asymmetric ring.”
ANSWER: first image of a black hole [accept equivalents; accept answers describing the image of the supermassive black hole at the center of Messier 87 or the image of M87* (“M-87-star”)]
[10h] The dark spot in the center of the image of M87* (“M-87-star”) contains this region of space in which light orbits the black hole. There are no stable free-fall orbits that cross this region whose radius is three-halves the Schwarzschild radius.
ANSWER: photon sphere [or photon circle or last photon orbit]
[10e] The Schwarzschild radius is the radius of this “horizon,” the boundary beyond which light cannot escape a black hole.
ANSWER: event horizon
<Michael Bentley, Science - Astronomy> ~18084~ <Editor: David Bass>