标题： 关于星系际氢电离率的限制来自Lyman-alpha森林 opacity 显示英文标题

标题： Constraints on the metagalactic hydrogen ionization rate from the Lyman-alpha forest opacity

摘要： 理解导致宇宙再电离的辐射源是观测宇宙学的关键目标之一。 如果根据适当假设调整Lyman-α森林早期流体力学模拟得出的星系际介质温度，则其中性氢电离率Gamma_HI与由邻近效应预测的值之间存在差异。 我们基于Lyman-α森林吸收率的流体力学模拟给出了红移区间2<z<4的新估算值。 在当前一致的宇宙学框架下，并假定更新的类星体发射率，似乎在整个红移范围内都需要年轻恒星形成星系对紫外背景做出显著贡献。 我们的结果与邻近效应的低端估算值一致。 研究还发现，电离率的误差主要受星系际介质热状态以及重力尺度上均方根波动幅度的不确定性影响。 显示英文摘要

摘要： Understanding the sources responsible for reionizing the Universe is a key goal of observational cosmology. A discrepancy has existed between the metagalactic hydrogen ionization rate, Gamma_HI, predicted by early hydrodynamical simulations of the Lyman-alpha forest if scaled to appropriate assumptions for the IGM temperature, when compared to values predicted from the proximity effect. We present new estimates for Gamma_HI in the redshift range 2<z<4 based on hydrodynamical simulations of the Lyman-alpha forest opacity. Within the current concordance cosmology, and assuming updated QSO emissivity rates, a substantial contribution to the UV background from young star-forming galaxies appears to be required over the entire redshift range. Our results are consistent with lower-end estimates from the proximity effect. It is also found that the errors on the ionization rate are dominated by uncertainties in the thermal state of the intergalactic medium and the r.m.s fluctuation amplitude at the Jeans scale.