Physical origin of the dark spot at the image of supermassive black hole SgrA* revealed by the EHT collaboration

TL;DR

This paper explains that the dark spot in the EHT image of SgrA* is the northern hemisphere of the event horizon, not the classical black hole shadow, revealing its physical origin.

Contribution

It provides a physical interpretation of the dark spot as the event horizon's northern hemisphere, clarifying the nature of the observed feature in the EHT image.

Findings

Dark spot corresponds to the northern hemisphere of the event horizon.

The classical black hole shadow is not visible in the image.

The dark spot is projected within the classical shadow region.

Abstract

We elucidate the physical origin of the dark spot in the image of supermassive black hole SgrA* presented very recently by the EHT collaboration. It is argued that this dark spot, which is noticeably smaller than the classical black hole shadow, is the northern hemisphere of the event horizon globe. The classical black hole shadow is unseen in the image of SgrA*. The dark spot in the image of SgrA* is projected within the position of the classical black hole shadow on the celestial sphere. The outer boundary of this dark spot is an equator on the event horizon globe.