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Astrophysics, Relativity, and Cosmology Seminar - Alex Lupsasca (Vanderbilt) "The Black Hole Photon Ring"

Event Type
Seminar/Symposium
Sponsor
Department of Physics
Location
Loomis 464
Virtual
wifi event
Date
Oct 9, 2024   12:00 pm  
Speaker
Alex Lupsasca
Contact
Deanna Frye
E-Mail
ddebord@illinois.edu
Views
6
Originating Calendar
Physics - Astrophysics, Relativity, and Cosmology Seminar

What does a black hole look like? The first images of the supermassive black hole M87* display a bright ring encircling the event horizon, which appears as a dark patch in its surrounding emission. But Einstein's theory of general relativity predicts that within this image there also lies a thin "photon ring" consisting of multiple mirror images of the main emission. These images arise from photons that orbited around the black hole multiple times, probing the warped space-time geometry just outside its horizon. The photon ring carries an imprint of the strong gravity in this region and encodes fundamental properties of the black hole. A measurement of this predicted (but not yet observed) ring could provide a precise test of general relativity and will be one of the main targets of a NASA mission proposed to fly within the next decade: the Black Hole Explorer (BHEX). 

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