标题： JWST发现的微弱活动星系核对再电离的影响 显示英文标题

标题： The impact of faint AGN discovered by JWST on reionization

摘要： 由JWST揭示的在$4\lesssim z\lesssim11$处明显的微弱AGN高丰度，再次引发了对恒星源发射和超大质量黑洞吸积对再电离的相对贡献的关注。我们使用基于GPU的辐射转移代码ATON-HE，通过对SHERWOOD-RELICS模拟套件中的宇宙学流体动力学模拟进行后处理，研究这些微弱AGN对氢气和氦气再电离早期阶段的贡献。我们研究了四种再电离模型：两种之前研究过的仅星系晚期结束再电离模型以及两种新的模型——类星体辅助模型和类星体仅模型。在类星体辅助模型中，1%的晕宿主AGN，其寿命为10~Myr，并且AGN的光度被调整，使得AGN对氢电离发射率的贡献为星系贡献的20%。在类星体仅模型中，类星体负责所有氢电离发射率，其中10%的晕宿主AGN，每个具有10 Myr的寿命。所有模型都校准到在$5\lesssim z\lesssim6.2$处观测到的平均Lyman-$\alpha$森林透射率。我们发现，在再电离结束时，类星体辅助模型所需的发射率因子比仅星系模型低$1.8$，并且很好地拟合了观测到的Lyman-$\alpha$光深分布。我们的类星体仅模型与观测到的Lyman-$\alpha$光深分布不一致。由于HeII再电离的过早开始，它还会导致$z\lesssim 5$处的IGM温度过高，除非假设HeII电离光子的逃逸分数较低。 我们的结果表明，微弱活动星系核对再电离的适度贡献与莱曼-$\alpha$谱线数据是一致的。 相反，以微弱活动星系核为主导的情景似乎难以与这些观测结果相协调。 显示英文摘要

摘要： The relative contribution of emission from stellar sources and accretion onto supermassive black holes to reionization has been brought into focus again by the apparent high abundance of faint AGN at $4\lesssim z\lesssim11$ uncovered by JWST. We investigate the contribution of these faint AGN to hydrogen and the early stages of helium reionization using the GPU-based radiative transfer code ATON-HE by post-processing a cosmological hydrodynamical simulation from the SHERWOOD-RELICS suite of simulations. We study four models of reionization: two previously studied galaxy-only late-end reionization models and two new models -- a QSO-assisted model and a QSO-only model. In the QSO-assisted model, 1\% of the haloes host AGN with a 10~Myr lifetime, and the AGN luminosities are scaled such that the AGN contribution to the hydrogen-ionizing emissivity is 20\% of that contributed by galaxies. In the QSO-only model, quasars account for all the hydrogen-ionizing emissivity, with 10\% of the haloes hosting AGN, each with a 10 Myr lifetime. All models are calibrated to the observed mean Lyman-$\alpha$ forest transmission at $5\lesssim z\lesssim6.2$. We find that the QSO-assisted model requires an emissivity factor of $1.8$ lower than the galaxy-only models towards the end of reionization and fits the observed distribution of the Lyman-$\alpha$ optical depths well. Our QSO-only model is inconsistent with the observed Lyman-$\alpha$ optical depths distribution. It also results in too high IGM temperatures at $z\lesssim 5$ due to an early onset of HeII reionization unless the escape fraction of HeII-ionizing photons is assumed to be low. Our results suggest that a modest contribution to reionization by faint AGN is in good agreement with the Lyman-$\alpha$ forest data. In contrast, a scenario dominated by faint AGN appears difficult to reconcile with these observations.