论文标题
$ f（r，t）$重力的时间依赖于时间的时空：重力崩溃
A Time Dependent Spacetime in $f(R,T)$ Gravity: Gravitational Collapse
论文作者
论文摘要
在本说明中，通过巨大恒星的重力崩溃，在$ f（r，t）$重力的背景中探索了时间上的时空。恒星是由vaidya时空建模的，这本质上是时间的。物质与曲率的耦合是$ f（r，t）$理论的关键特征，在这里我们研究了它对崩溃的情况的影响。我们的研究考虑了两种不同类型的模型，一种涉及最小的模型，另一种涉及物质和曲率之间的非最小耦合。功率定律和指数功能被视为检查重力崩溃结果的例子。我们的主要目的是探索形成奇异性的性质（黑洞或裸露的奇异性），即崩溃的末端状态。探究了中央奇点的外向径向零用测量学的存在，这种存在暗示着裸奇异性的形成，因此违背了宇宙审查假设。没有这种外向的无效测量学将暗示事件视野的形成，而形成的奇异性变成了黑洞。所有模型和子模型都会得出这种可能性的条件。还研究了奇异性的引力强度，并得出了强大或弱奇异性的条件。获得的结果非常有趣，可能归因于曲率和物质之间的耦合。可以看出，对于非最小耦合，有可能具有全球裸露的奇异性，而对于最小的耦合方案而言，本地裸露是唯一的选择。还发现形成的奇异性本质上可能足够弱，这在宇宙学上是可取的。
In this note a time dependent spacetime is explored in the background of $f(R,T)$ gravity via the gravitational collapse of a massive star. The star is modelled by the Vaidya spacetime which is time dependent in nature. The coupling of matter with curvature is the key feature of $f(R,T)$ theory and here we have investigated its effects on a collapsing scenario. Two different types of models, one involving minimal and the other involving non-minimal coupling between matter and curvature are considered for our study. Power law and exponential functionalities are considered as examples to check the outcome of the gravitational collapse. Our prime objective is to explore the nature of singularities (black hole or naked singularity) that form as an end state of the collapse. Existence of outgoing radial null geodesics from the central singularity was probed and such existence implied the formation of naked singularities thus defying the cosmic censorship hypothesis. The absence of such outgoing null geodesics would imply the formation of an event horizon and the singularity formed becomes a black hole. Conditions under which such possibilities occur are derived for all the models and sub-models. Gravitational strength of the singularity is also investigated and the conditions under which we can get a strong or a weak singularity is derived. The results obtained are very interesting and may be attributed to the coupling between curvature and matter. It is seen that for non-minimal coupling there is a possibility of a globally naked singularity, whereas for a minimal coupling scenario local nakedness is the only option. It is also found that the singularity formed can be sufficiently weak in nature, which is cosmologically desirable.
