https://doi.org/10.1140/epjp/s13360-023-04482-4
Regular Article
Near horizon approximation and beyond for a two-level atom falling into a Kerr–Newman black hole
Department of Astrophysics and High Energy Physics, S.N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake, 700106, Kolkata, India
a sensohomhary@gmail.com, soham.sen@bose.res.in
Received:
21
June
2023
Accepted:
14
September
2023
Published online:
27
September
2023
In this work, we investigate the phenomena of acceleration radiation for a two-level atom falling into the event horizon of a Kerr–Newman black hole. In Azizi et al. (Phys Rev D 104:065006, 2021), it has been shown that conformal quantum mechanics has a connection to the generated Planck-like spectrum due to acceleration radiation. In this particular aspect, the near horizon approximation played a significant role. In Sen et al. (Phys Rev D 106:025004, 2022), we have used the beyond near horizon approximation to show that the excitation probability attains a Planck-like spectrum irrespective of the non-existence of an underlying conformal symmetry for a general class of static spherically symmetric black holes. In our current analysis, we have gone beyond the near horizon approximation for the rotating and charged case, and without the consideration of the conformal symmetry, we no longer observe an overall Planck-like spectrum. We instead observe that the excitation probability consists of several lower incomplete gamma functions which deform the near horizon conformal behaviour of the spectrum. Finally, we have computed the von Neumann entropy which is also known as the horizon brightened acceleration radiation entropy or the HBAR entropy. The calculation of the rate of change of the von Neumann entropy suggests that there is a loss of thermality because of the inclusion of the contributions from the beyond near horizon terms.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2023. 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.
