GRAVITATIONAL COLLAPSE IN D-DIMENSIONAL RASTALL GRAVITY WITH COSMOLOGICAL CONSTANT

• Main Author: Ekatria, Golfin
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/66452
• Institution: Institut Teknologi Bandung

When a massive star exhausting its nuclear fuel, the star will begins to collapse under its own gravity. At that time there is no force that can counterbalance its gravitational force so that the endless gravitational collapse occurs. According to general relativity, the outcome of the gravitational collapse would be a space-time singularity. If an event horizon has formed before the singularity forms, then the gravitational collapse would end in black hole. Otherwise, when the horizon formation is delayed during the collapse so that the extreme density and curvature may fail to be covered by the horizon, then the gravitational collapse would end in naked singularity. There are some gravitational collapse models such as Oppenheimer and Snyder models suggests that the collapse will only end in black hole. This is in accordance with the cosmic censorship conjecture (CCC) which state that singularity always covered by horizon. The problem is that CCC still doesn’t have a proof either mathematically or by observation. In addition, the other gravitational collapse models are reviewed with modified theory of gravity such as ????(?) gravity, Brans-Dicke theory, Lovelock gravity showing the existence of the solution of naked singularity. These results can be considered as counterexample of CCC. Another possibility that indeed appears worth exploring is that we may actually living in higher-dimensional spacetime. The recent developments in string theory strongly indicate that gravity is possibly a higher dimensional interaction. Hence, there is a possibility that CCC may be fail in four-dimensional manifold but it may be well in higher dimensional manifold due to extra physical effects arising from the transition of our dimension to higher-dimensional spacetime. Such considerations would inspire the study of the gravitational collapse. Another consideration is that in general relativity, there is a constant known as cosmological constant. This constant was originally add by Einstein to model a static universe. In next few years, Hubble’s observe that our universe is expanding. Practically the cosmological constant is non-zero but very small so that the cosmological constant can be our consideration in modelling the gravitational collapse. Therefore, this thesis studies the gravitational collapse in d-dimensional Rastall gravity with cosmological constant. The energy momentum tensor in this studies is perfect fluid. From this model, we investigate several parameters value such as Rastall parameter, barotropic index, dimensions that determine the outcome of the collapsing process. Then, we also determine the solution of interior and exterior metric in order to obtained the complete spacetime metric.