The Supersonic Project: SIGOs, A Proposed Progenitor to Globular Clusters, and Their Connections to Gravitational-wave Anisotropies
The Supersonic Project: SIGOs, A Proposed Progenitor to Globular Clusters, and Their Connections to Gravitational-wave Anisotropies
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DOI：
10.3847/1538-4357/ac20d0
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发表时间：
2021-04
期刊：
影响因子：
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通讯作者：
William Lake;S. Naoz;Yeou S. Chiou;B. Burkhart;F. Marinacci;M. Vogelsberger;K. Kremer
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文献类型：
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作者：
William Lake;S. Naoz;Yeou S. Chiou;B. Burkhart;F. Marinacci;M. Vogelsberger;K. Kremer
超音速诱导气体天体（英语：Supersonically induced gas objects，缩写为SIRST）是一种几乎没有暗物质成分的结构，预计存在于宇宙中重子和暗物质在复合时具有较大相对速度的区域。它们被认为是现今球状星团的祖先。使用模拟，SITERS已经研究了小尺度（约2百万秒差距），这些相对速度是相干的。然而，它是具有挑战性的，研究SITERS使用模拟在大尺度上，由于不同的相对速度在尺度大于几个百万分之一秒差距。在这里，我们研究SIGO丰度半解析：使用微扰理论，我们预测的数密度SIGO解析，并比较这些结果的小盒子数值模拟。我们使用的数值和分析计算之间的协议外推的大规模变化的SIGO丰度在不同的流速。因此，我们预测类似的大尺度变化的对象与高气体密度的再电离之前，可能会观察到的JWST。如果SIOR确实是球状星团的祖先，那么我们预计球状星团丰度在大尺度上也会有类似的变化。值得注意的是，我们发现，预期的数密度的SINUS是一致的观测到的球状星团的数密度。作为一个概念的证明，因为球状星团被认为是自然形成的网站引力波源从二进制黑洞合并，我们表明，SITERA应该印上各向异性的引力波信号在天空中，与他们的分布一致。
Supersonically induced gas objects (SIGOs), are structures with little to no dark-matter component predicted to exist in regions of the universe with large relative velocities between baryons and dark matter at the time of recombination. They have been suggested to be the progenitors of present-day globular clusters. Using simulations, SIGOs have been studied on small scales (around 2 Mpc) where these relative velocities are coherent. However, it is challenging to study SIGOs using simulations on large scales due to the varying relative velocities at scales larger than a few Mpc. Here, we study SIGO abundances semi-analytically: using perturbation theory, we predict the number density of SIGOs analytically, and compare these results to small-box numerical simulations. We use the agreement between the numerical and analytic calculations to extrapolate the large-scale variation of SIGO abundances over different stream velocities. As a result, we predict similar large-scale variations of objects with high gas densities before reionization that could possibly be observed by JWST. If indeed SIGOs are progenitors of globular clusters, then we expect a similar variation of globular cluster abundances over large scales. Significantly, we find that the expected number density of SIGOs is consistent with observed globular cluster number densities. As a proof-of-concept, and because globular clusters were proposed to be natural formation sites for gravitational wave sources from binary black-hole mergers, we show that SIGOs should imprint an anisotropy on the gravitational wave signal on the sky, consistent with their distribution.