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

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 space-time geometry also holds an important role. We present an image depicting the bright hotspots 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 10 233 AU. The central supermassive black hole located at the centre of the Galaxy has an observational mass of $4.14\times 10^6\, \, \rm M_{\odot }$ and the secondary eclipsing black hole has an inferred mass of $1035\, \, \rm M_{\odot }$.