Population III and the near-infrared background excess
Population III and the near-infrared background excess
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群体 III 和近红外背景过剩
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发表时间：
2005
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通讯作者：
Piero MadauJoseph Silk
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作者：
Piero MadauJoseph Silk
我们做了一个关键的评估模型，属性最近检测到的近红外背景“过剩”（NIRBE）的红移光从人口III对象。为了提供红移9时每个重子所需的25 keV能量，第三星族大质量恒星必须以超过30%的效率在所有维里温度高于几百K的“迷你晕”中形成;为了避免过度的金属污染，第三星族恒星中的大多数重子必须最终进入中等质量黑洞（IMBH）。在这种IMBH上的气体吸积必须被抑制或导致具有陡峭的紫外/X射线光谱的早期小型类星体，以避免过度产生目前尚未解决的软X射线背景。在后一种情况下（NIRBE由“X射线安静的小型类星体”主导），在z = 1.9处的IMBH的总质量密度必须比今天在星系核中观察到的超大质量黑洞的质量密度高出1.50倍。一个以恒星为主导的近红外线辐射平衡在能量上是不太经济的：宇宙中所有重子的15%必须被处理成第三星族恒星。我们调查的各个方面的人口III假设的NIRBE，并表明，电离光子预算需要占的NIRBE是远远大于所需的解释高电子散射光学厚度的WMAP卫星测量。
We make a critical assessment of models that attribute the recently detected near-infrared background ‘excess’ (NIRBE) to the redshifted light from Population III objects. To supply the required 25 keV per baryon at redshift 9, Population III massive stars must form with an efficiency exceeding 30 per cent in all ‘minihaloes’ with virial temperatures above a few hundred kelvins; to avoid excessive metal pollution, most of the baryons once in Population III stars must end up in intermediate-mass black holes (IMBHs). Gas accretion on to such IMBHs must either be inhibited or lead to early miniquasars with steep ultraviolet/X-ray spectra, in order not to overproduce the present-day unresolved soft X-ray background. In the latter case (NIRBE dominated by ‘X-ray-quiet miniquasars’), the total mass density of IMBHs at z∼ 9 must be ≳50 times higher than the mass density of supermassive black holes observed today in the nuclei of galaxies. A stellar-dominated NIRBE is less economical energetically: ≳5 per cent of all baryons in the Universe must be processed into Population III stars. We survey various aspects of the Population III hypothesis for the NIRBE, and show that the ionizing photon budget required to account for the NIRBE is much larger than that required to explain the high electron scattering optical depth measured by the WMAP satellite.