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SUMMARY:The Black Hole Photon Ring - Alexandru Lupsasca (Princeton)
DTSTART:20220304T130000Z
DTEND:20220304T140000Z
UID:TALK168338@talks.cam.ac.uk
CONTACT:Prahar Mitra
DESCRIPTION:\nThe photon ring is a narrow ring-shaped feature\, predicted 
 by General Relativity but not yet observed\, that appears on images of sou
 rces near a black hole. It is caused by extreme bending of light within a 
 few Schwarzschild radii of the event horizon and provides a direct probe o
 f the unstable bound photon orbits of the Kerr geometry. I will review the
  origin and structure of the photon ring\, before discussing the prospects
  for its detection. I will argue that the precise shape of the observable 
 photon ring is remarkably insensitive to the astronomical source profile a
 nd can therefore be used as a stringent test of strong-field General Relat
 ivity. A space-based interferometry experiment targeting the photon ring o
 f M87* could test the Kerr nature of the source to the sub-percent level. 
 I will discuss a NASA proposal to launch such a mission before the end of 
 the decade.
LOCATION:Zoom
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