Black hole shadow to probe modified gravity

A. Stepanian; Sh. Khlghatyan; V. G. Gurzadyan

doi:10.1140/epjp/s13360-021-01119-2

EPJ

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2022 Impact factor 3.4

EPJ PLUS - Condensed Matter and Complex Systems

Focus Point on Modified Gravity Theories and Cosmology

Eur. Phys. J. Plus (2021) 136: 127
https://doi.org/10.1140/epjp/s13360-021-01119-2

Letter to the Editor

Black hole shadow to probe modified gravity

A. Stepanian¹, Sh. Khlghatyan¹ and V. G. Gurzadyan¹^,2^c

¹ Center for Cosmology and Astrophysics, Alikhanian National Laboratory, Yerevan State University, Yerevan, Armenia
² SIA, Sapienza Universita di Roma, Rome, Italy

^c gurzadyan@yerphi.am

Received: 5 January 2021
Accepted: 13 January 2021
Published online: 23 January 2021

Abstract

We study the black hole’s shadow for Schwarzschild–de Sitter and Kerr–de Sitter metrics with the contribution of the cosmological constant . Based on the reported parameters of the M87* black hole shadow, we obtain constraints for the and show the agreement with the cosmological data. It is shown that the coupling of the -term with the spin parameter reveals peculiarities for the photon spheres and hence for the shadows. Within the parametrized post-Newtonian formalism, the constraint for the corresponding -determined parameter is obtained.