Probing the initial mass function of the first stars with transients
Probing the initial mass function of the first stars with transients
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用瞬变探测第一批恒星的初始质量函数
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
V. Bromm
中科院分区：
文献类型：
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作者：
Alexander Lazar;V. Bromm
第一批恒星的出现，即所谓的第三星族（Pop III），它们塑造了早期宇宙的历史，其方式关键取决于它们的初始质量函数（IMF）。然而，由于缺乏直接的观察约束，详细的IMF数据仍然难以捉摸。尽管如此，数值模拟大体上同意，第一批恒星通常是巨大的，它们的生命通常会在剧烈的、爆炸性的死亡中结束。这些命运包括极其明亮的对不稳定超新星（PISNe）和明亮的伽马射线暴（grb），后者是由快速旋转的祖恒星坍缩成黑洞引起的。这些高红移瞬变预计将在即将到来的太空望远镜任务的探测范围内，允许对原始IMF的形状进行有效的限制，这是其他探测器不容易接近的。本文提出了一个利用高红移PISNe和grb的宇宙学源密度来探测Pop III IMF的框架。单独考虑这些瞬态可以为Pop III IMF提供有用的约束，但通过结合PISN和GRB计数可以获得更严格的约束。这种综合诊断更加可靠，因为它不依赖于潜在的Pop III恒星形成速率密度，这是一个未知的先验。未来的调查有望捕获整个天空中大多数高红移grb，但未来望远镜（如罗马太空望远镜）的高红移PISN搜索可能会基本上不完整。然而，我们证明，即使是PISN计数的下限也能够对原始IMF提供关键约束，特别是如果它是头重脚轻的。
The emergence of the first, so-called Population III (Pop III), stars shaped early cosmic history in ways that crucially depends on their initial mass function (IMF). However, because of the absence of direct observational constraints, the detailed IMF remains elusive. Nevertheless, numerical simulations agree in broad terms that the first stars were typically massive and should often end their lives in violent, explosive deaths. These fates include extremely luminous pair-instability supernovae (PISNe) and bright gamma-ray bursts (GRBs), the latter arising from the collapse of rapidly rotating progenitor stars into black holes. These high-redshift transients are expected to be within the detection limits of upcoming space telescope missions, allowing to place effective constraints on the shape of the primordial IMF that is not easily accessible with other probes. This paper presents a framework to probe the Pop III IMF, utilizing the cosmological source densities of high-redshift PISNe andGRBs. Considering these transients separately could provide useful constraints on the Pop III IMF, but tighter bounds are obtainable by combining PISN and GRB counts. This combined diagnostic is more robust as it is independent of the underlying Pop III star formation rate density, an unknown prior. Future surveys promise to capture most high-redshift GRBs across the entire sky, but high-redshift PISN searches with future telescopes, e.g. Roman Space Telescope, will likely be substantially incomplete. Nevertheless, we demonstrate that even such lower bounds on the PISN count will be able to provide key constraints on the primordial IMF, in particular, if it is top-heavy or not.