A census of baryons in the Universe from localized fast radio bursts
A census of baryons in the Universe from localized fast radio bursts
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DOI：
10.1038/s41586-020-2300-2
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发表时间：
2020-05
期刊：
影响因子：
64.8
通讯作者：
J. Macquart;J. Prochaska;J. Prochaska;M. McQuinn;K. Bannister;S. Bhandari;C. Day;C. Day;
中科院分区：
文献类型：
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作者：
J. Macquart;J. Prochaska;J. Prochaska;M. McQuinn;K. Bannister;S. Bhandari;C. Day;C. Day;
宇宙中超过四分之三的重子内容存在于一种很难探测到的高度扩散状态，只有一小部分是在星系和星系团中直接观察到的。对邻近宇宙的普查使用了吸收谱线光谱技术来观测“看不见的”重子，但这些测量依赖于大的和不确定的修正，并且对宇宙的大部分体积，甚至可能是其大部分质量都不敏感。特别是，类星体光谱对原子态中存在的极少量氢，或者对星系附近密度更高的区域中高度电离和浓缩的气体都很敏感。其他观察这些看不见的重子的技术也有局限性；Sunyaev-Zel‘dovich分析可以从丝状结构中的气体中提供证据，而X射线发射的研究对星系团附近的气体最敏感。在这里，我们报道了一种利用局部快速射电爆发样本的色散来测量宇宙中重子含量的方法；这项技术确定了沿每一条视线的电子柱密度，并解释了每个电离重子-。我们在主星系中增加了四个新的局部化射电爆发，测量到了0.291，0.118，0.378和0.522的红移，从而增加了已报道的弧次局部化射电爆发的样本。这就完成了一个足够大的样本，足以解释沿着视线和在宿主星系环境中的色散变化，我们得到了宇宙重子密度(95%的置信度；H70=H0/(70公里S−1Mpc−1)，H0是哈勃常数)。这种独立的测量结果与来自宇宙微波背景和大爆炸核合成的值是一致的。
More than three-quarters of the baryonic content of the Universe resides in a highly diffuse state that is difficult to detect, with only a small fraction directly observed in galaxies and galaxy clusters,. Censuses of the nearby Universe have used absorption line spectroscopy,to observe the ‘invisible’ baryons, but these measurements rely on large and uncertain corrections and are insensitive to most of the Universe’s volume and probably most of its mass. In particular, quasar spectroscopy is sensitive either to the very small amounts of hydrogen that exist in the atomic state, or to highly ionized and enriched gas, –in denser regions near galaxies. Other techniques to observe these invisible baryons also have limitations; Sunyaev–Zel’dovich analyses,can provide evidence from gas within filamentary structures, and studies of X-ray emission are most sensitive to gas near galaxy clusters,. Here we report a measurement of the baryon content of the Universe using the dispersion of a sample of localized fast radio bursts; this technique determines the electron column density along each line of sight and accounts for every ionized baryon, –. We augment the sample of reported arcsecond-localized, , , –fast radio bursts with four new localizations in host galaxies that have measured redshifts of 0.291, 0.118, 0.378 and 0.522. This completes a sample sufficiently large to account for dispersion variations along the lines of sight and in the host-galaxy environments, and we derive a cosmic baryon density of(95 per cent confidence;h70=H0/(70 km s−1Mpc−1) andH0is Hubble’s constant). This independent measurement is consistent with values derived from the cosmic microwave background and from Big Bang nucleosynthesis,.