Institute for Advanced Study Astrophysics Seminar

"Observing" Jet/Accretion Flow/Black Hole (JAB) Simulations (Now with Positrons!)

Recent radio observations of inflowing and outflowing plasma in the vicinity of supermassive black holes are linked to simple phenomenological models via general relativistic magnetohydrodynamic simulations through a methodology called "Observing" Jet/Accretion flow/Black hole (JAB) Systems. For M87, HARM jet simulations are viewed from Very Large Array (43 GHz) to Event Horizon Telescope (230 GHz) scales to replicate the observed collimation and magnetic field configuration, while serving as the basis for a self-similar, stationary, axisymmetric force-free jet model used to generate polarization maps and spectra. 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 and spectra are found to be observationally distinguishable through positron effects such as decreasing intrinsic circular polarization and Faraday rotation and conversion. For Sagittarius A* in our Galactic Center, we include a turbulent heating electron temperature model exponential in the plasma beta (gas-to-magnetic pressure ratio). Intensity map 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 torus with flat spectrum; and 4.) extended outflow with flat spectrum. These models may be distinguishable by the Event Horizon Telescope. Future applications of "Observing" (JAB) Systems are considered.


Date & Time

October 07, 2021 | 11:00am – 12:00pm


Bloomberg Lecture Hall and Zoom


Richard Anantua

Speaker Affiliation

Harvard University, CfA

Event Series