Did globular clusters reionize the Universe
Did globular clusters reionize the Universe
复制标题
球状星团是否使宇宙重新电离
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
M. Ricotti
中科院分区：
文献类型：
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作者：
M. Ricotti
宇宙学中尚未解决的一个问题是识别能够通过 z∼6 使星际介质 (IGM) 中的 H I 重新电离的辐射源。理论工作和观测似乎表明，从星系发出的逃逸到 IGM 中的 HI 电离辐射的比例 (f e sc ) 在当地宇宙中很小（(f e sc )？ 10%）。在高红移下，星系更加致密，并且可能富含气体，这意味着它们的盘或球体的 (f e sc ) 值较小。然而，如果恒星形成的地点远离圆盘或球体，并且原星团的恒星形成效率很高，那么(f e sc )应该约为1。这种恒星形成情景与球状星团形成的几种模型是一致的。使用基于本地宇宙中观测到的球状星团系统数量的简单论证，并假设最古老的球状星团在再电离之前形成并且具有 (f e sc ) ∼1，我表明它们产生了足够的电离光子以在 z 6 处重新电离 IGM。
A problem still unsolved in cosmology is the identification of the sources of radiation able to reionize H I in the intergalactic medium (IGM) by z∼6. Theoretical work and observations seem to indicate that the fraction,(f e s c ), of HI ionizing radiation emitted from galaxies that escapes into the IGM is small in the local Universe ((f e s c )? 10 per cent). At high redshift, galaxies are more compact and probably gas-rich, implying smaller values of (f e s c ) from their discs or spheroids. However, if the sites of star formation are displaced from the disc or spheroid and the star formation efficiency of the proto-clusters is high, then (f e s c ) should be about 1. This star formation scenario is consistent with several models for globular cluster formation. Using simple arguments based on the observed number of globular cluster systems in the local Universe, and assuming that the oldest globular clusters formed before reionization and had (f e s c ) ∼1, I show that they produced enough ionizing photons to reionize the IGM at z 6.