标题： SKA时代观测高红移射电明亮类星体的前景：为21厘米森林观测铺平道路 显示英文标题

标题： Prospects for Observing High-redshift Radio-loud Quasars in the SKA Era: Paving the Way for 21-cm Forest Observations

摘要： 21厘米森林是研究再电离时期（EoR）早期加热过程和小尺度结构的敏感探针，这将通过即将建成的平方公里阵列（SKA）实现。 其探测依赖于射电明亮背景源的存在，其中射电明亮类星体非常有前景，但由于观测有限，它们在EoR期间的丰度仍不清楚。 在这里，我们使用一个物理驱动模型来预测未来的射电明亮类星体观测。 我们利用高红移类星体的观测数据来拟合该模型的参数。 假设爱丁顿吸积，该模型给出了在$z\sim6$处类星体的平均寿命为$t_{\rm q} \sim 10^{5.3}$年，这与最近从类星体邻近区预研究中得到的结果一致。 我们表明，如果类星体的射电明亮比例随红移变化，它将显著减少SKA时代可观察到的射电明亮类星体的丰度，使21厘米森林研究变得具有挑战性。 在射电明亮比例恒定的情况下，我们的模型表明，使用SKA-LOW进行一年的天空调查能够检测到大约20个在$z\sim 9$处的射电明亮类星体，具有足够的灵敏度来解析单独的21厘米森林线。 显示英文摘要

摘要： The 21-cm forest is a sensitive probe for the early heating process and small-scale structures during the epoch of reionization (EoR), to be realized with the upcoming Square Kilometre Array (SKA). Its detection relies on the availability of radio-bright background sources, among which the radio-loud quasars are very promising, but their abundance during the EoR is still poorly constrained due to limited observations. Here, we use a physics-driven model to forecast future radio-loud quasar observations. We fit the parameters of the model using observational data of high-redshift quasars. Assuming Eddington accretion, the model yields an average lifetime of $t_{\rm q} \sim 10^{5.3}$yr for quasars at $z\sim6$, consistent with recent results obtained from quasar proximity zone pre-study. We show that if the radio-loud fraction of quasars evolves with redshift, it will significantly reduce the abundance of observable radio-loud quasars in the SKA era, making 21-cm forest studies challenging. With a constant radio-loud fraction, our model suggests that a one-year sky survey conducted with SKA-LOW has the capability to detect approximately 20 radio-loud quasars at $z\sim 9$, with sufficient sensitivity to resolve individual 21-cm forest lines.