Beyond Imaging: Near-Horizon Physics from Movies and Polarization Maps Based on GRMHD Simulations
Abstract
Sgr A* emission models based on turbulent plasma heating and deviations from equipartition of particle and magnetic energies are input into a High Accuracy Relativistic Magnetohydrodynamics (HARM) simulation. Variability analysis of movies simulating hourly timescales shows that these models aggregate into four quasi-stationary 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 low frequency spectral knee. For M87, a self-similar, stationary, axisymmetric jet model based on a force-free flow in a HARM jet simulation is used to generate Stokes maps at Very Long Baseline Array (VLBA, 43 GHz) and Event Horizon Telescope (EHT, 230 GHz) scales. The 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 be constant fractions of the local magnetic pressure. The cleanest observational signature in the Stokes maps is the vanishing of circular polarization for increasing positron content. Autocorrelation analysis shows one linear polarization tends to bilaterally asymmetry and the other, antisymmetry, in a frequency-dependent manner that may break model degeneracies given upcoming EHT observations.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23541102A