Constraints on Black Hole Jet Models Used As Diagnostic Tools of Event Horizon Telescope Observations of M87

Abstract

Jet models of Event Horizon Telescope (EHT) data should also conform to the observed jet profiles just downstream. This study evaluates conformance of models of black hole (BH) jets to images of the innermost jet of M87. This is a basic test that should be passed before using them to perform a physical interpretation of EHT data. Recent 86 GHz very long baseline interferometry observations of M87 have revealed the morphology and size of the jet near its source (<65 M , or 0.06 lt-yr after correcting for the line of sight to the jet, where M is the BH mass in geometrized units) for the first time. Current transverse resolution indicates that this region is dominated by flux emanating from the edge of the jet. The observed inner jet profiles are compared to all existing published synthetic radio images constructed from “state of the art” 3D numerical simulations of the BH accretion system in M87. Despite efforts to produce the characteristic wide, edge-dominated jet, these models are too narrow (by a factor of ∼2) in the region 0.06–0.32 lt-yr from the source, even though the jets (spine and/or sheath) in the image plane might appear conformant farther downstream. Furthermore, the synthetic radio images are not edge dominated 0.06–0.32 lt-yr from the source, but spine dominated. Analyses that implement these models as physical diagnostics of EHT visibility amplitudes are therefore suspect. Thus, these inner-jet characteristics are important considerations before applying simulations to the EHT data.