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arXiv 2005.01874astro-ph.COgr-qchep-th
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考虑再加热过程中状态方程参数的时间演化

Accounting for the time evolution of the equation of state parameter during reheating

Pankaj Saha, Sampurn Anand, L. Sriramkumar

备注：
v1: 10 pages, 5 figures; v2: 13 pages, 7 figures, discussions and references added, version to apprear in Phys. Rev. D
发表信息：
Phys. Rev. D 102, 103511 (2020)
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摘要：

宇宙学中的一个重要参数是表征驱动宇宙膨胀的源的状态方程的参数。由辐射、物质或标量场主导的时期，无论是直接探测还是间接探测，都可以用这个参数的唯一值来表征。然而，在再加热期间的EoS参数-一个被认为会迅速膨胀我们宇宙的阶段-仍然需要令人满意的理解。为了避免在再加热期间定义瞬时EoS参数的复杂性，通常考虑有效参数$w_\mathrm{eff}$，其是再加热持续时间内EoS参数的平均值。$w_\mathrm{eff}$的值通常被任意选择为位于范围$-1/3 \leq w_\mathrm{eff} \leq 1$内。在这项工作中，我们考虑的时间演化的EoS参数在再加热过程中，并将其与通货膨胀的潜力$V(ϕ)$，表现为$ϕ^p$周围的最小值，一个建议，可以适用于广泛的一类通货膨胀模型。我们发现，给定指数$p$，有效的EoS参数$w_{\rm eff}$是唯一确定的。我们讨论了相应的再加热温度的影响及其含义。

英文摘要：

One of the important parameters in cosmology is the parameter characterizing the equation of state (EoS) of the sources driving the cosmic expansion. Epochs that are dominated by radiation, matter, or scalar fields, whether they are probed either directly or indirectly, can be characterised by a unique value of this parameter. However, the EoS parameter during reheating---a phase succeeding inflation which is supposed to rapidly defrost our universe---remains to be understood satisfactorily. In order to circumvent the complexity of defining an instantaneous EoS parameter during reheating, an effective parameter $w_\mathrm{eff}$, which is an average of the EoS parameter over the duration of reheating, is usually considered. The value of $w_\mathrm{eff}$ is often chosen arbitrarily to lie in the range $-1/3 \leq w_\mathrm{eff} \leq 1$. In this work, we consider the time evolution of the EoS parameter during reheating and relate it to inflationary potentials $V(ϕ)$ that behave as $ϕ^p$ around the minimum, a proposal which can be applied to a wide class of inflationary models. We find that, given the index $p$, the effective EoS parameter $w_{\rm eff}$ is determined uniquely. We discuss the corresponding effects on the reheating temperature and its implications.

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