https://doi.org/10.1140/epjp/s13360-024-04904-x
Regular Article
Gravitational collapse without singularity formation in Brans–Dicke theory
1
Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), University of Maragheh, P.O. Box 55136-553, Maragheh, Iran
2
Physics Department, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan, Iran
Received:
14
November
2023
Accepted:
14
January
2024
Published online:
9
February
2024
In the present work we study collapse process of a homogeneous and isotropic fluid in Brans–Dicke (BD) theory with non-vanishing spacetime torsion. In this theory, torsion can be generated by the BD scalar field as well as the intrinsic angular momentum (spin) of matter. Assuming the matter content of the collapsing body to be a Weyssenhoff fluid, which is a generalization of perfect fluid in general relativity (GR) in order to include the spin effects, we find that in BD theory with torsion, the existence of spin effects could avoid the spacetime singularity that forms in the original version of this theory (Scheel et al. in Phys Rev D 51:4208, 1995, Scheel et al. in Phys Rev D 51:4236, 1995). Numerical simulations of collapse model show that the spacetime singularity is replaced by a non-singular bounce, the spacetime event at which the collapse process halts at a minimum radius and then turns into an expanding phase. Moreover, the model parameters can be set so that the apparent horizon will never meet the boundary of the collapsing body so that the bounce event can be detectable by external observers in the Universe.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2024. 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.
