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SUMMARY:Alex Lupsasca (Princeton Gravity Initiative)
DTSTART:20210212T184500Z
DTEND:20210212T194500Z
DTSTAMP:20260423T010251Z
UID:PUHET/11
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/PUHET/11/">T
 he Black Hole Photon Ring</a>\nby Alex Lupsasca (Princeton Gravity Initiat
 ive) as part of Princeton HET seminar\n\n\nAbstract\nThe photon ring is a 
 narrow ring-shaped feature\, predicted by GR but not yet observed\, that a
 ppears on images of sources near a black hole. It is caused by extreme ben
 ding of light within a few Schwarzschild radii of the event horizon and pr
 ovides a direct probe of the unstable bound photon orbits of the Kerr geom
 etry. I will review the origin and structure of the photon ring\, before d
 iscussing the prospects for its future detection. I will argue that the pr
 ecise shape of the observable photon ring is remarkably insensitive to the
  astronomical source profile and can therefore be used as a stringent test
  of GR. A space-based interferometry experiment targeting the photon ring 
 of M87* could test the Kerr nature of the source to the sub-sub-percent le
 vel.\n
LOCATION:https://researchseminars.org/talk/PUHET/11/
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