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arXiv 2102.01524gr-qc
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Rastall引力场中引力星的研究

Study of Gravastars in Rastall Gravity

Shounak Ghosh, Sagar Dey, Amit Das, Anirban Chanda, B C Paul

摘要:

在过去的几十年里,重力星被认为是黑洞的可行替代品。除了标准的广义相对论(GR)外,许多引力理论都研究了引力星的稳定模型。拉斯塔尔引力理论是一个流行的替代GR,特别是在宇宙学和天体物理学的背景下。在这里,我们根据Mazur-Mottola的\cite{Mazur2001,Mazur2004}猜想,提出了一个Rastall引力下的恒星模型。重力仪由三个区域组成,即,($I$)内部区域、($II$)中间壳区域和($III$)外部区域。假设内部核区域内的压力具有恒定的负物质-能量密度,其在整个薄壳区域上提供排斥力。假设壳层由超相对论等离子体流体组成,遵循Zel'dovich的刚性流体猜想\cite{Zeldo1962,Zel'dovich1972}。根据Zel'dovich猜想,还假设压力与物质-能量密度成正比,这抵消了内部区域施加的排斥力。外部区域是完全真空的Schwarzschild-de Sitter解。在所有这些规格下,我们得到一组精确的和无奇异性的解决方案的引力模型,提出了几个物理上有效的功能的框架内的Rastall重力。探讨了壳层区域的物理性质,即能量密度、固有长度、总能量和熵。在Rastall引力的框架下,利用表面红移对壳层厚度的影响和壳层熵的最大化,研究了引力星模型的稳定性。

英文摘要:

Gravastars have been considered as a feasible alternative to black holes in the past couple of decades. Stable models of gravastar have been studied in many of the alternative gravity theories besides standard General Relativity (GR). The Rastall theory of gravity is a popular alternative to GR, specially in the cosmological and astrophysical context. Here, we propose a stellar model under the Rastall gravity following Mazur-Mottola's \cite{Mazur2001,Mazur2004} conjecture. The gravastar consists of three regions, viz., ($I$) Interior region, ($II$) Intermediate shell region, and ($III$) Exterior region. The pressure within the interior core region is assumed with a constant negative matter-energy density which provides a repulsive force over the entire thin shell region. The shell is assumed to be made up of fluid of ultrarelativistic plasma which follows the Zel'dovich's conjecture of stiff fluid \cite{Zeldo1962,Zel'dovich1972}. It is also assumed that the pressure is proportional to the matter-energy density according to Zel'dovich's conjecture, which cancel the repulsive force exerted by the interior region. The exterior region is completely vacuum which is described by the Schwarzschild-de Sitter solution. Under all these specifications we obtain a set of exact and singularity-free solutions of the gravastar model presenting several physically valid features within the framework of Rastall gravity. The physical properties of the shell region namely, the energy density, proper length, total energy and entropy are explored. The stability of the gravastar model is investigated using the surface redshift against the shell thickness and maximizing the entropy of the shell within the framework of Rastall gravity.

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