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arXiv 2309.04533astro-ph.COhep-phhep-th
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利用高红移莱曼阿尔法森林揭示最小尺度下的暗物质自由流动

Unveiling Dark Matter free-streaming at the smallest scales with high redshift Lyman-alpha forest

Vid Iršič, Matteo Viel, Martin G. Haehnelt, James S. Bolton, Margherita Molaro, Ewald Puchwein, Elisa Boera, George D. Becker, Prakash Gaikwad, Laura C. Keating, Girish Kulkarni

AI总结:

本研究利用高红移类星体光谱的Lyman-$α$森林通量功率谱,通过贝叶斯推断框架将热遗迹温暗物质粒子质量的下限限制在5.7 keV,揭示了高质量光谱样本对提升暗物质自由流动约束的关键作用。

摘要:

本研究利用Lyman-$α$森林通量功率谱,对热遗迹温暗物质(WDM)的自由流动引入了新的限制。我们的分析使用了通过HIRES和UVES光谱仪观测到的高分辨率、高红移类星体光谱样本($z=4.2-5.0$)。我们采用贝叶斯推断框架和基于模拟的似然函数,该函数包含暗物质自由流动、宇宙学参数、星际介质热历史以及非均匀再电离等各种参数,从而确立了热遗迹WDM粒子质量的下限为$5.7\\;\mathrm{keV}$(在95%置信水平下)。该结果通过更大的统计样本以及测量更小尺度($k_{\rm max}=0.2\\;\mathrm{km^{-1}\\,s}$)的聚集性来降低测量不确定性,从而超越了以往来自Lyman-$α$森林的限制。由于统计样本扩大带来的约两倍提升表明,Lyman-$α$森林对高红移WDM模型的限制有效性受限于高质量类星体光谱的可用性。将分析限制在以往研究中可比拟的尺度和热历史先验下($k_{\rm max}<0.1\\;\mathrm{km^{-1}\\,s}$),将WDM质量的限制降低至$4.1\\;\mathrm{keV}$。随着测量精度的提高,检验仪器和建模系统误差变得至关重要。在建模方面,我们认为由于独立观测的改进,热历史不确定性对WDM粒子质量限制的影响已经减小。在最小尺度上,建模系统误差的主要来源是星际介质 peculiar velocity 的结构以及非均匀再电离。

英文摘要:

This study introduces novel constraints on the free-streaming of thermal relic warm dark matter (WDM) from Lyman-$α$ forest flux power spectra. Our analysis utilises a high-resolution, high-redshift sample of quasar spectra observed using the HIRES and UVES spectrographs ($z=4.2-5.0$). We employ a Bayesian inference framework and a simulation-based likelihood that encompasses various parameters including the free-streaming of dark matter, cosmological parameters, the thermal history of the intergalactic medium, and inhomogeneous reionization, to establish lower limits on the mass of a thermal relic WDM particle of $5.7\;\mathrm{keV}$ (at 95\% C.L.). This result surpasses previous limits from the Lyman-$α$ forest through reduction of the measured uncertainties due to a larger statistical sample and by measuring clustering to smaller scales ($k_{\rm max}=0.2\;\mathrm{km^{-1}\,s}$). The approximately two-fold improvement due to the expanded statistical sample suggests that the effectiveness of Lyman-$α$ forest constraints on WDM models at high redshifts are limited by the availability of high-quality quasar spectra. Restricting the analysis to comparable scales and thermal history priors as in prior studies ($k_{\rm max}<0.1\;\mathrm{km^{-1}\,s}$) lowers the bound on the WDM mass to $4.1\;\mathrm{keV}$. As the precision of the measurements increases, it becomes crucial to examine the instrumental and modelling systematics. On the modelling front, we argue that the impact of the thermal history uncertainty on the WDM particle mass constraint has diminished due to improved independent observations. At the smallest scales, the primary source of modeling systematic arises from the structure in the peculiar velocity of the intergalactic medium and inhomogeneous reionization.

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