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Non-singular Brans–Dicke collapse in deformed phase space
Authors:SMM Rasouli  AH Ziaie  S Jalalzadeh  PV Moniz
Institution:1. Departamento de Física, Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã, Portugal;2. Centro de Matemática e Aplicações (CMA - UBI), Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã, Portugal;3. Physics Group, Qazvin Branch, Islamic Azad University, Qazvin, Iran;4. Department of Physics, Shahid Beheshti University, G. C., Evin, 19839 Tehran, Iran;5. Department of Physics, Shahid Bahonar University, PO Box 76175, Kerman, Iran;6. Federal University of Latin-American Integration, Technological Park of Itaipu PO box 2123, Foz do Iguaçu-PR, 85867-670, Brazil
Abstract:We study the collapse process of a homogeneous perfect fluid (in FLRW background) with a barotropic equation of state in Brans–Dicke (BD) theory in the presence of phase space deformation effects. Such a deformation is introduced as a particular type of non-commutativity between phase space coordinates. For the commutative case, it has been shown in the literature (Scheel, 1995), that the dust collapse in BD theory leads to the formation of a spacetime singularity which is covered by an event horizon. In comparison to general relativity (GR), the authors concluded that the final state of black holes in BD theory is identical to the GR case but differs from GR during the dynamical evolution of the collapse process. However, the presence of non-commutative effects influences the dynamics of the collapse scenario and consequently a non-singular evolution is developed in the sense that a bounce emerges at a minimum radius, after which an expanding phase begins. Such a behavior is observed for positive values of the BD coupling parameter. For large positive values of the BD coupling parameter, when non-commutative effects are present, the dynamics of collapse process differs from the GR case. Finally, we show that for negative values of the BD coupling parameter, the singularity is replaced by an oscillatory bounce occurring at a finite time, with the frequency of oscillation and amplitude being damped at late times.
Keywords:Brans&ndash  Dicke theory  Non-commutative geometry  Gravitational collapse  Spacetime singularity
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