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arXiv 1805.03076gr-qc
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Brans-Dicke引力中物质和暗能量密度参数及其相互作用项的时间演化

Time Evolution of Density Parameters for Matter and Dark Energy and their Interaction Term in Brans-Dicke Gravity

Sudipto Roy, Dipika Nandi, Sumana Ghosh, Apashanka Das

摘要:

在Brans-Dicke(BD)理论的框架下,本文第一部分确定了加速膨胀后减速阶段宇宙流体的BD参数、能量密度和状态方程(EoS)参数随时间的变化关系。为此,选择了比例因子,使得从其获得的减速参数显示出随时间的特征翻转。考虑到暗能量对整个压强的贡献,确定了物质和暗能量的能量参数随时间的演化以及暗能量的EoS参数。提出并计算了物质与暗能量的有效相互作用项。它在目前的负值表明物质转化为暗能量。利用这一项,物质和暗能量的变化率的时间依赖性已被确定。我们发现,标量场对标度因子的依赖性在控制所研究的宇宙学量的时间演化中起着非常重要的作用。本研究为我们提供了一个简单的方法来确定暗能量的时间演化的均匀和各向同性的宇宙的空间曲率为零,而不涉及任何自相互作用势或宇宙学常数的制定。

英文摘要:

In the framework of Brans-Dicke (BD) theory, the first part of the present study determines the time dependence of BD parameter, energy density and equation of state (EoS) parameter of the cosmic fluid in a universe expanding with acceleration, preceded by a phase of deceleration. For this purpose, a scale factor has been chosen such that the deceleration parameter, obtained from it, shows a signature flip with time. Considering the dark energy to be responsible for the entire pressure, the time evolution of energy parameters for matter and dark energy and the EoS parameter for dark energy have been determined. An effective interaction term, between matter and dark energy, has been proposed and calculated. Its negative value at the present time indicates conversion of matter into dark energy. Using this term, the time dependence of the rates of change of matter and dark energy has been determined. It is found that the nature of dependence of the scalar field upon the scale factor plays a very important role in governing the time evolution of the cosmological quantities studied here. The present study provides us with a simple way to determine the time evolution of dark energy for a homogeneous and isotropic universe of zero spatial curvature, without involving any self-interaction potential or cosmological constant in the formulation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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