Events: October 20, 2020


Tuesday Lunch Seminar: Richard Anantua (CfA, Harvard): "Towards Understanding Near-Horizon Physics of Sgr A* from Movies and Polarization Maps"

1:00–2:00 pm Zoom

Recent radio observations of emitting magnetized plasma in the vicinity of Sagittarius A* (Sgr A*) in our Galactic Center are linked to simple electron temperature parametric models based on turbulent heating and conversion of magnetic to particle energy in general relativistic magnetohydrodynamic (GRMHD) simulations and related analytic models. GRMHD-based intensity map movies simulating hourly timescales show that these models aggregate into at least four morphological types: 1.) Thin, asymmetric photon ring; 2.) Coronal boundary layer with thin photon ring; 3.) Thick photon ring; and 4.) Extended outflow. Positrons are added in a semi-analytic, radiatively inefficient accretion flow model for which polarization maps are sensitive to positron effects of decreasing intrinsic circular polarization and increasing Faraday conversion.

Oct 20