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arXiv 2402.14079astro-ph.COastro-ph.GA
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原初磁场:一致的初始条件及其对高红移结构的影响

Primordial magnetic fields: consistent initial conditions and impact on high-z structures

Pranjal Ralegankar, Mak Pavičević, Matteo Viel

AI总结:

本文通过首次考虑原初磁场对重子和暗物质不同影响的流体动力学模拟,发现原初磁场能增强小尺度功率谱并产生高重子分数星系,且可用Sheth-Torman形式主义准确描述晕质量函数。

摘要:

原初磁场(PMFs)可以增强小尺度($\lesssim$ Mpc)上的物质功率谱,同时仍与宇宙微波背景(CMB)和法拉第旋转测量的约束保持一致。由于小于Mpc尺度上的模式在今天已经变得非线性,探索原初磁场对小尺度结构的影响需要专门的宇宙学模拟。在这里,我们首次进行了一系列流体动力学模拟,考虑了原初磁场对重子和暗物质的不同影响。具体而言,在初始条件中,我们根据原初磁场的洛伦兹力来移动粒子。我们还强调了原初磁场导致的物质功率谱峰值增强中存在较大的理论不确定性,这一点在以往的研究中未被考虑。我们展示了晕质量函数,并表明它们可以使用Sheth-Torman形式主义准确再现。此外,我们表明原初磁场可以在高红移下产生重子分数比宇宙平均值大数倍的星系。这仅仅是原初磁场增强重子扰动,使其大于暗物质扰动的结果。我们认为,通过获取高红移星系中重子分数的准确估计,这一情景很快就能得到检验。

英文摘要:

Primordial magnetic fields (PMFs) can enhance matter power spectrum on small scales ($\lesssim$ Mpc) and still agree with bounds from cosmic microwave background (CMB) and Faraday rotation measurements. As modes on scales smaller than Mpc have already become non-linear today, exploring PMFs' impact on small-scale structures requires dedicated cosmological simulations. Here, for the first time, we perform a suite of hydrodynamical simulations that take into account the different impacts of PMFs on baryons and dark matter. Specifically, in the initial conditions we displace particles according to the Lorentz force from PMFs. We also highlight the large theoretical uncertainty in the peak enhancement of the matter power spectrum due to PMFs, which was not considered in previous studies. We present halo mass functions and show that they can be accurately reproduced using Sheth-Torman formalism. Moreover, we show that PMFs can generate galaxies with baryon fraction several times larger than the cosmic average at high redshifts. This is simply a consequence of the fact that PMFs enhance baryon perturbations, causing them to be larger than dark matter perturbations. We argue that this scenario could be tested soon by obtaining accurate estimates of the baryon fraction in high redshift galaxies.

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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