Simulating Observations of M87 with the Event Horizon Telescope and Space VLBI

The Event Horizon Telescope (EHT), composed of many sub-millimeter radio telescopes across the globe, uses Very-Long-Baseline Interferometry (VLBI) to act as a telescope the size of the Earth. In 2019, the EHT released the first image of a black hole, the super massive black hole at the center of M87. Such images have the potential to provide insight on highly distorted areas of space-time, the perfect environment to test General Relativity (GR) and to study the astrophysics of jet formation. However, the EHT's angular resolution of ~20 microarcseconds does not provide enough detail to resolve important features such as radiative outbursts surrounding the accretion disk, nor to measure the shape and position of the photon ring at physically interesting levels. Here we simulate observations of general relativistic magnetohydrodynamic (GRMHD) models of the Kerr black hole M87 with the EHT in conjunction with various satellite arrays to demonstrate how the extension of the EHT into Earth orbit will benefit imaging. Satellite arrays consisting of two satellites just above Geosynchronous Earth Orbit (GEO) yield an angular resolution of ~3 microarcseconds, providing the ability to observe radiative outbursts as well as a highly resolved photon ring. These arrays provide sharper, more faithful images of M87 and demonstrate the ability to produce spatially resolved, time-resolved movies of the jet-launch region. We further discuss the effects of non-circularity in the shadow and the offset of its center due to frame dragging. This work was supported by grants (AST-1440254, AST-1614868, AST-1950348, AST-2034306) from the National Science Foundation.