https://doi.org/10.1140/epjp/s13360-024-05933-2
Regular Article
Influence of primary hair and plasma on intensity distribution of black hole shadows
1
Physics Department, Herzen State Pedagogical University of Russia, 48 Moika Emb., 191186, Saint Petersburg, Russia
2
SPb Branch of SAO RAS, 65 Pulkovskoe Rd, 196140, Saint Petersburg, Russia
3
Department of High Energy and Elementary Particles Physics, Saint Petersburg State University, University Emb. 7/9, 199034, Saint Petersburg, Russia
4
International Center for Space and Cosmology, Ahmedabad University, 380009, Ahmedabad, Gujarat, India
5
Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, IAG, Rua do Matão 1225, CEP: 05508-090, São Paulo - SP, Brazil
Received:
30
March
2024
Accepted:
14
December
2024
Published online:
12
January
2025
In this paper, we investigate the influence of primary hair (l) on the shadows of hairy Schwarzschild and Reissner-Nordström black holes obtained through gravitational decoupling. In the context of hairy Schwarzschild black holes, l either has no effect or consistently enlarges the photon sphere radius. Notably, even when it violates the strong energy condition, it can decrease the radius. For Reissner-Nordström black holes, an additional matter field consistently expands the photon sphere radius, potentially reaching 3M, akin to the pure Schwarzschild case. Remarkably, we demonstrate that black holes can exist even when overcharged (
), casting shadows. Specific intensity calculations reveal l consistently reduces it in both scenarios. Furthermore, we investigate the impact of pressureless plasma, finding l exerts a stronger influence on visible size than plasma. These results can help in our understanding of theoretical models of black hole shadows and can be tested by comparison with the images obtained by EHT collaboration.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
