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Dr. Anautua will talk on, "A Glimpse into EHT-Scale Physics Using Movies and Polarization Maps."

Abstract:

Recent radio observations of emission from infalling and outflowing plasma in the vicinity of supermassive black holes are linked to simple phenomenological models via general relativistic magnetohydrodynamic simulations using a methodology called "Observing" Jet (or outflow)/Accretion flow/Black hole (JAB) Simulations. For Sagittarius A* in our Galactic Center, movies simulating hourly timescales show that these models can be classified into at least four types: 1.) thin, asymmetric photon ring with best fit spectrum; 2.) coronal boundary layer with thin photon ring and steep spectrum; 3.) thick photon ring with flat spectrum; and 4.) extended outflow with flat spectrum. For M87, a self-similar, stationary, axisymmetric model based on a force-free flow in a HARM jet simulation is used to generate Stokes maps at Global mm-VLBI Array (86 GHz) and Event Horizon Telescope (230 GHz) scales. This model varies plasma content from ionic (e-p) to pair (e-e+). Emission at the observed frequency is assumed to be synchrotron radiation from electrons and positrons, whose pressure is set to relate to the local magnetic pressure through parametric prescriptions.  Polarization maps are found to be sensitive to the positron effects of decreasing intrinsic circular polarization and increased Faraday conversion.

 

Bio:

Dr. Richard Anantua is a postdoctoral fellow at the Center for Astrophysics | Harvard & Smithsonian and Black Hole Initiative at Harvard. As a member of the Event Horizon Telescope Collaboration, Richard links observational features of near-horizon shadows of supermassive black holes to the plasma physics of nearby accretion disks and jets which light them up. Prior to Harvard, Richard held a postdoctoral/instructor position at U.C. Berkeley after completing his Ph.D. in Physics at Stanford under Prof. Roger Blandford and a B.S. from Yale in (Physics & Philosophy) and (Economics & Mathematics).

 

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If you are interested in attending this seminar, email sullivam@reed.edu for the zoom link.