The Thermal and Gravitational Energy Densities in the Large-scale Structure of the Universe
The Thermal and Gravitational Energy Densities in the Large-scale Structure of the Universe
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DOI：
10.3847/1538-4357/abe387
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
Y. Chiang;R. Makiya;E. Komatsu;B. M'enard
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文献类型：
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作者：
Y. Chiang;R. Makiya;E. Komatsu;B. M'enard
随着宇宙结构的形成，物质密度波动在重力作用下崩溃，重子物质受到冲击加热和热化。因此，我们预计塌陷晕的平均重力势能密度 和重子的平均热能密度 Ωth 之间存在联系。这些量可以通过两种根本不同的估计来获得：我们使用由暗物质统计驱动的晕模型的理论框架进行计算，并使用 Sunyaev-Zeldovich (SZ) 效应来测量 Ωth，该效应探测重子的平均热压力。首先，我们推导出，目前大约90%源自M > 1013 M ⊙ 的大质量晕。然后，利用我们对 SZ 背景的测量，我们发现 Ωth 约占 z ≲ 0.5 时晕中压力可用的重子动能的 80%。这限制了非热压力的大小，例如，由于质量吸积引起的体积和湍流气体运动，在 z = 0 时约为 Ωnon‐th ≃ 0.4 × 10−8 。
As cosmic structures form, matter density fluctuations collapse gravitationally and baryonic matter is shock-heated and thermalized. We therefore expect a connection between the mean gravitational potential energy density of collapsed halos, , and the mean thermal energy density of baryons, Ωth. These quantities can be obtained using two fundamentally different estimates: we compute using the theoretical framework of the halo model, which is driven by dark matter statistics, and measure Ωth using the Sunyaev–Zeldovich (SZ) effect, which probes the mean thermal pressure of baryons. First, we derive that, at the present time, about 90% of originates from massive halos with M > 1013 M ⊙. Then, using our measurements of the SZ background, we find that Ωth accounts for about 80% of the kinetic energy of the baryons available for pressure in halos at z ≲ 0.5. This constrains the amount of nonthermal pressure, e.g., due to bulk and turbulent gas motion sourced by mass accretion, to be about Ωnon‐th ≃ 0.4 × 10−8 at z = 0.