Modeling the shadow of Sgr A* through an eclipsing black hole

TL;DR

This paper models the shadow of Sgr A* by simulating an eclipsing black hole system, providing insights into the observed emission features and variability, and highlighting the role of spacetime geometry.

Contribution

It introduces a novel image simulation of Sgr A* involving an eclipsing Schwarzschild black hole along the line of sight, exploring effects on observed brightness and variability.

Findings

Simulated bright hot spots consistent with EHT observations.

Eclipsing black hole influences the observed emission structure.

The model suggests spacetime geometry impacts observed variability.

Abstract

The Event Horizon Telescope (EHT) observations of Sgr\,A* resolved the shadow image and emission ring-like structure, which is associated to the photon ring of the supermassive black hole, at the galactic centre, revealing a diameter of $51.8~\mu \text{as}$. The ring-like structure is consistent with that of a Kerr black hole. However, the source of the high bright regions in the image and the time variability remain an open question. Besides the plasma properties and emission models, the spacetime geometry also holds an important role. We present an image depicting the bright hot spots consistent with Sgr\,A* observations at a wavelength $ \lambda = 1.3\, {\rm mm}$. The image is the result of an eclipsing Schwarzschild black hole situated along the line of sight between the galactic centre and Earth. The separation from both, primary (Sgr\,A*) and secondary (eclipsing) black holes is $10233\, {\rm AU}$. The central supermassive black hole located at the centre of the galaxy has an observational mass of $4.14\times10^6\,M_{\odot}$ and the secondary eclipsing black hole has an inferred mass of $1035\,M_{\odot}$.