In the present work, we study spherically symmetric gravitational collapse of a homogeneous fluid in the framework of Rastall gravity. Considering a nonlinear equation of state (EoS) for the fluid profiles, we search for a class of nonsingular collapse solutions and the possibility of singularity removal. We find that depending on the model parameters, the collapse scenario halts at a minimum value of the scale factor at which a bounce occurs. The collapse process then enters an expanding phase in the postbounce regime, and consequently the formation of a spacetime singularity is prevented. We also find that, in comparison to the singular case where the apparent horizon forms to cover the singularity, the formation of apparent horizon can be delayed allowing thus the bounce to be causally connected to the external universe. The nonsingular solutions we obtain satisfy the weak energy condition (WEC) which is crucial for physical validity of the model.

中文翻译：

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拉斯塔尔理论中的引力坍塌和奇异消除

在目前的工作中，我们研究了在Rastall重力框架下均质流体的球对称重力塌陷。考虑到流体剖面的非线性状态方程（EoS），我们搜索了一类非奇异的塌陷解和奇异性消除的可能性。我们发现，取决于模型参数，崩溃场景会在发生反弹的比例因子的最小值处停止。塌陷过程然后进入后反弹状态的扩展阶段，因此可以防止时空奇异点的形成。我们还发现，与视在地平线形成以覆盖奇点的奇异情况相比，视在地平线的形成可以延迟，从而使反弹与外部宇宙有因果关系。