The Extragalactic Serendipitous Swift Survey (ExSeSS) - I. Survey definition and measurements of the X-ray number counts
The Extragalactic Serendipitous Swift Survey (ExSeSS) - I. Survey definition and measurements of the X-ray number counts
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河外偶然快速巡天 (ExSeSS) - I. 巡天定义和 X 射线计数测量
DOI：
10.1093/mnras/stac3703
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发表时间：
2023
影响因子：
4.8
通讯作者：
Delaney J
中科院分区：
文献类型：
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作者：
Delaney J
我们提出了河外偶发性雨燕调查（ExSeSS），提供了一个新的定义明确的样本，从使用雨燕X射线望远镜进行的观测。ExSeSS样本由79342个源组成，在中等（1-2 keV），硬（2-10 keV）或总（0.3-10 keV）能带中检测到，覆盖2086.6 deg 2的天空，通量范围为0.3 -10 keV <$10 −15− 10− 10 erg s− 1 cm −2。使用新的ExSeSS样品，我们提出了测量的X射线源的微分计数作为2-10千电子伏通量的函数，跟踪人口的活动星系核（AGN）在以前未探索的制度。我们发现，考虑视线吸收柱密度对微分计数测量有影响，并且对于与以前的结果取得一致至关重要。在硬带，我们得到了很好的协议之间的ExSeSS测量和以前的，更高的能量数据从NuSTAR和斯威夫特/BAT考虑到不同的列密度的ExSeSS样品以及X射线光谱参数的每个样品，我们正在比较。我们还发现ExSeSS测量和活动星系核人口合成模型之间的差异，表明在这个通量范围内活动星系核人口的性质发生了变化，这在这些能量下并没有被当前的模型完全描述，暗示了一个更大的，适度模糊的人口在低红移（z = 0.2），模型目前没有考虑。
We present the Extragalactic Serendipitous Swift Survey (ExSeSS), providing a new well-defined sample constructed from the observations performed using the Swift X-ray Telescope. The ExSeSS sample consists of 79 342 sources detected in the medium (1–2 keV), hard (2–10 keV), or total (0.3–10 keV) energy bands, covering 2086.6 deg2of sky across a flux range off0.3–10 keV∼ 10−15− 10−10erg s−1cm−2. Using the new ExSeSS sample we present measurements of the differential number counts of X-ray sources as a function of 2–10 keV flux that trace the population of Active Galactic Nuclei (AGNs) in a previously unexplored regime. We find that taking the line-of-sight absorption column density into account has an effect on the differential number count measurements and is vital to obtain agreement with previous results. In the hard band, we obtain a good agreement between the ExSeSS measurements and previous, higher energy data fromNuSTARandSwift/BAT when taking into account the varying column density of the ExSeSS sample as well as the X-ray spectral parameters of each of the samples we are comparing to. We also find discrepancies between the ExSeSS measurements and AGN population synthesis models, indicating a change in the properties of the AGN population over this flux range that is not fully described by current models at these energies, hinting at a larger, moderately obscured population at low redshifts (z≲ 0.2) that the models are not currently taking into account.