Imaging thick accretion disks and jets surrounding black holes

TL;DR

This paper models and simulates millimeter-wave images of thick accretion disks and funnel walls around Kerr black holes, revealing how emission anisotropy and flow structures influence observable features like the photon ring.

Contribution

It introduces a detailed magnetofluid model for thick disks and funnel walls, analyzing their imaging signatures and the effects of emission anisotropy on observability.

Findings

Anisotropic synchrotron radiation affects photon ring visibility.

Outflow funnel walls produce brighter primary images than photon rings.

Inflow funnel wall models remain consistent with M87* observations.

Abstract

Based on the horizon-scale magnetofluid model developed in [arXiv:2309.13304], we investigate the millimeter-wave images of a geometrically thick accretion disk or a funnel wall, i.e., the magnetofluid that encloses the base of the jet region, around a Kerr black hole. By employing the numerical method to solve the null geodesic and radiative transfer equations, we obtain the optical appearances at various observational angles and frequencies, generated by the thermal synchrotron radiation within the magnetofluid. For the thick disk, we specifically examine the impact of emission anisotropy on images, concluding that anisotropic synchrotron radiation could play an important role in the observability of the photon ring. For the funnel wall, we find that both the outflow and inflow funnel walls exhibit annular structures on the imaging plane. The outflow funnel wall yields a brighter primary image than the photon ring, whereas the inflow one does not. Based on our investigation, the inflow funnel wall model can not be ruled out by current observations of M87*.