标题： 再电离过程对星际介质热历史的约束 显示英文标题

标题： Constraints on reionization from the thermal history of the intergalactic medium

摘要： 电离气体介质（IGM）的温度取决于其再电离历史，因为热时间尺度很长。在遥远类星体光谱中看到的氢Lyman-alpha吸收线的宽度可以用来确定其温度。我们对类星体光谱中Lyman-alpha森林区域进行小波分析，以证明在红移z=3.5和3.0之间，吸收线宽度有相对突然的增加，我们将这一现象归因于HeII再电离导致的熵注入。在z~3.5之后温度的下降与以绝热膨胀为主的热演化一致。如果如预期的那样，在氢再电离后温度也迅速下降，那么在HeII再电离之前从线宽推断出的高温意味着氢再电离发生在红移z=9以下。 显示英文摘要

摘要： The temperature of the diffuse, photo-heated intergalactic medium (IGM) depends on its reionization history because the thermal time scales are long. The widths of the hydrogen Lyman-alpha absorption lines seen in the spectra of distant quasars that arise in the IGM can be used to determine its temperature. We use a wavelet analysis of the Lyman-alpha forest region of quasar spectra to demonstrate that there is a relatively sudden increase in the line widths between redshifts z=3.5 and 3.0, which we associate with entropy injection resulting from the reionization of HeII. The subsequent fall-off in temperature after z~3.5, is consistent with a thermal evolution dominated by adiabatic expansion. If, as expected, the temperature also drops rapidly after hydrogen reionization, then the high temperatures inferred from the line widths before HeII reionization imply that hydrogen reionization occurred below redshift z=9.