Shadows and thin accretion disk images of the [Formula omitted]-metric

• Published in: The European physical journal. C, Particles and fields Vol. 82; no. 8
• Main Authors: Shaikh, Rajibul, Paul, Suvankar, Banerjee, Pritam, Sarkar, Tapobrata
• Format: Journal Article
• Language: English
• Published: Springer 01.08.2022
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-022-10664-8

The [Formula omitted]-metric is a static, axially-symmetric singular solution of the vacuum Einstein's equations without an event horizon. This is a two-parameter family of solutions, generic values of one of which (called [Formula omitted]) measure the deviation from spherical symmetry. We show that this can serve as a black hole mimicker, consistent with current observations. To this end, we first study the shadow cast by this geometry, in order to constrain the [Formula omitted]-metric from observations. We find that for [Formula omitted], there are, in principle, no shadows cast. On the other hand, shadows cast for all values of [Formula omitted] are consistent with observations of M [Formula omitted] by the Event Horizon Telescope. We also study images of thin accretion disks in the [Formula omitted]-metric background. In situations where the [Formula omitted]-metric possesses light rings, these qualitatively mimic Schwarzschild black holes with the same ADM mass, while in the absence of such rings, they are drastically different from the black hole case.