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

## TL;DR

This study assesses whether current black hole jet models match observed inner jet profiles of M87, revealing that many models are too narrow and not edge dominated near the jet source, questioning their use as diagnostic tools.

## Contribution

It provides a critical evaluation of existing 3-D numerical jet models against recent high-resolution observations of M87's innermost jet region.

## Key findings

- Models are too narrow by a factor of ~2 near the jet source.
- Synthetic images are spine dominated, not edge dominated, close to the black hole.
- Current models may be unreliable for interpreting EHT data.

## 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 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-yrs after correcting for line of sight to the jet, where $M$ is the black hole 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" 3-D numerical simulations of the black hole accretion system in M87. Despite efforts to produce the characteristic wide, edge dominated jet, these models are too narrow (by a factor of $\sim2$) in the region 0.06 - 0.32 lt-yrs 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-yrs 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.