<p>We study spherically symmetric gravitational collapse of an inhomogeneous fluid with anisotropic energy momentum tensor (EMT) in Rastall gravity. Considering a linear equation of state (EoS) for the fluid profiles, i.e., <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(p_r=w_r\rho\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>p</mi> <mi>r</mi> </msub> <mo>=</mo> <msub> <mi>w</mi> <mi>r</mi> </msub> <mi>ρ</mi> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(p_\theta =w_\theta \rho\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>p</mi> <mi>θ</mi> </msub> <mo>=</mo> <msub> <mi>w</mi> <mi>θ</mi> </msub> <mi>ρ</mi> </mrow> </math></EquationSource> </InlineEquation>, we try to build and investigate non-singular collapse scenarios for which, the spacetime singularity that appears in the homogeneous case&#xa0;[<CitationRef CitationID="CR1">1</CitationRef>], is absent. We therefore set the Rastall parameter in such a way that the effective radial pressure vanishes. This helps us to obtain a class of exact nonsingular solutions in which the matter shells undergo a collapse process in a contracting regime, reach a bounce point, and then enter an expanding phase. We further investigate formation of trapped surfaces during the dynamical evolution of the collapsing body. It is found that for the obtained solutions, the trapped surface formation can be avoided and consequently, the bounce event is not covered by the apparent horizon. Validity of weak energy condition (WEC) is also examined for the obtained solutions.</p>

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Gravitational collapse of an inhomogeneous fluid in Rastall theory

  • Akbar Jahan,
  • Naser Sadeghnezhad,
  • Amir Hadi Ziaie

摘要

We study spherically symmetric gravitational collapse of an inhomogeneous fluid with anisotropic energy momentum tensor (EMT) in Rastall gravity. Considering a linear equation of state (EoS) for the fluid profiles, i.e., \(p_r=w_r\rho\) p r = w r ρ and \(p_\theta =w_\theta \rho\) p θ = w θ ρ , we try to build and investigate non-singular collapse scenarios for which, the spacetime singularity that appears in the homogeneous case [1], is absent. We therefore set the Rastall parameter in such a way that the effective radial pressure vanishes. This helps us to obtain a class of exact nonsingular solutions in which the matter shells undergo a collapse process in a contracting regime, reach a bounce point, and then enter an expanding phase. We further investigate formation of trapped surfaces during the dynamical evolution of the collapsing body. It is found that for the obtained solutions, the trapped surface formation can be avoided and consequently, the bounce event is not covered by the apparent horizon. Validity of weak energy condition (WEC) is also examined for the obtained solutions.