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arXiv 2406.11902astro-ph.HEgr-qchep-th
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引力 $\boldsymbol{f(R)}$ 与 $\boldsymbol{f(Q)}$ 理论中宇宙射线磁通量的磁场抑制

Magnetic Suppression of Cosmic Rays' Flux in $\boldsymbol{f(R)}$ and $\boldsymbol{f(Q)}$ Theories of Gravity

Swaraj Pratim Sarmah, Umananda Dev Goswami

AI总结:

本研究基于 $f(R)$ 和 $f(Q)$ 修改引力理论,从宇宙学角度计算了磁场扩散对超高能宇宙射线通量的抑制,发现修改引力理论对抑制因子有显著影响且标准模型结果介于两者之间。

摘要:

我们从宇宙学角度研究了磁场扩散对超高能宇宙射线(UHECRs)能谱的影响。为此,我们考虑了两种修改引力理论(MTGs),即 $f(R)$ 引力和对称遥平行引力(也称为 $f(Q)$ 引力)。利用这两种 MTGs,我们计算了一组源的 UHECRs 通量的抑制。在计算抑制因子时,我们考虑了非演化(NE)和宇宙恒星形成率(SFR)情景。本研究还包含了一个涉及直至铁(Fe)原子核的混合成分情景。此外,在考虑 NE 和 SFR 情景的情况下,我们分别给出了 $f(R)$ 和 $f(Q)$ 理论中质子及混合成分的抑制因子参数化。我们的工作还纳入了湍流磁场对抑制因子的影响。将所有结果与标准 $Λ$CDM 模型进行比较分析后发现,MTGs 对抑制因子有显著影响:$f(R)$ 幂律模型预测的抑制因子最低,而 $f(Q)$ 模型预测的最高,有趣的是,标准模型的结果恰好落在由这两种宇宙学模型预测的范围之内。

英文摘要:

We investigate the effects of magnetic diffusion on the spectrum of ultra-high energy cosmic rays (UHECRs) from a cosmological perspective. To this end, we consider two modified theories of gravity (MTGs), namely, the $f(R)$ gravity and a symmetric teleparallel gravity, also known as $f(Q)$ gravity. Utilizing these two MTGs, we calculate the suppression in the flux of UHECRs for a collection of sources. Non-evolution (NE) and cosmic star formation rate (SFR) scenarios have been considered in our calculation of the suppression factor. This study also includes a mixed composition scenario involving the nuclei upto iron (Fe). Furthermore, we provide a parameterization of the suppression factor for the proton and also for the mixed compositions within the $f(R)$ and $f(Q)$ theories, considering both NE and SFR scenarios. The influence of the turbulent magnetic field on the suppression factor is also incorporated in our work. Comparative analysis of all our results with the standard $Λ$CDM model reveals significant effects of MTGs on the suppression factor that the $f(R)$ power-law model predicts the lowest suppression factor, while the $f(Q)$ model predicts the highest, and interestingly the results from the standard model fall within the range predicted by these two cosmological models.

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