Hard X-ray luminosity function and absorption distribution of nearby AGN : INTEGRAL all-sky survey
Hard X-ray luminosity function and absorption distribution of nearby AGN : INTEGRAL all-sky survey
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DOI：
10.1051/0004-6361:20066277
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发表时间：
2006-08
影响因子：
6.5
通讯作者：
S. Sazonov;M. Revnivtsev;R. Krivonos;E. Churazov;R. Sunyaev
中科院分区：
文献类型：
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作者：
S. Sazonov;M. Revnivtsev;R. Krivonos;E. Churazov;R. Sunyaev
目标。我们研究局部 ($z\lesssim 0.1$) 活动星系核 (AGN) 的硬 X 射线光度函数和吸收分布，并讨论对 AGN 宇宙演化和宇宙 X 射线背景 (CXB) 的影响。方法。我们使用 INTEGRAL 全天硬 X 射线巡天对附近活动星系核的代表性样本进行统计研究。我们的整个全天空样本由 127 个 AGN 组成，其中 91 个在 IBIS/ISGRI 仪器获得的时间平均地图上被自信地检测到 (>$5\sigma$)，而 36 个仅在单次观测中检测到。其中，$|b|>5^\circ$处有66个非耀变活动星系核，勘测识别完成度约为93%，我们用它来计算活动星系核光度函数和X射线吸收分布。结果。与之前的研究基本一致，我们发现低光度 AGN ($L_{\rm hx} -1 ) 中被遮挡 (log$N_{\rm H}>22$) 物体的比例 f a 远高于高光度 AGN ($L_{\rm hx}>10^{43.6}$ erg s -1 ) 中的物体 (~$ 70$%)。 ), $f_{\rm a}\sim 25$%, 其中 L hx 是 17–60 keV 能带的光度。我们还发现，局部康普顿厚活动星系核的比例小于 20%，除非存在大量活动星系核，这些活动星系核被强烈遮蔽，以至于它们观测到的硬 X 射线光度低于 ~ 10 40 –10 41 erg s -1 ，即我们调查的有效极限。构造的硬X射线光度函数具有规范的、平滑打破的幂律形状，范围为$40 40$ is $(1.4\pm 0.3)\times 10^{39}$ erg s -1 Mpc -3 (17–60 keV)。我们证明，CXB 的光谱形状和幅度与简单场景一致，其中 AGN 的 N H 分布（对于给定的 $L_{\rm hx}/L_\ast(z)$ 比率）自 $z\sim 1.5$ 以来没有显着变化，而 AGN 光度函数经历了纯光度演化。
Aims. We study the hard X-ray luminosity function and absorption distribution of local ($z\lesssim 0.1$) active galactic nuclei (AGN) and discuss the implications for AGN cosmological evolution and for the cosmic X-ray background (CXB). Methods. We use the INTEGRAL all-sky hard X-ray survey to perform a statistical study of a representative sample of nearby AGN. Our entire all-sky sample consists of 127 AGN, of which 91 are confidently detected (>$5\sigma$) on the time-averaged map obtained with the IBIS/ISGRI instrument and 36 are detected only during single observations. Among the former there are 66 non-blazar AGN located at $|b|>5^\circ$, where the survey's identification completeness is ∼ 93%, which we use for calculating the AGN luminosity function and X-ray absorption distribution. Results. In broad agreement with previous studies, we find that the fraction f a of obscured (log$N_{\rm H}>22$) objects is much higher (~$ 70$%) among the low-luminosity AGN ($L_{\rm hx} -1 ) than among the high-luminosity ones ($L_{\rm hx}>10^{43.6}$ erg s -1 ), $f_{\rm a}\sim 25$%, where L hx is the luminosity in the 17–60 keV energy band. We also find that locally the fraction of Compton-thick AGN is less than 20% unless there is a significant population of AGN that are so strongly obscured that their observed hard X-ray luminosities fall below ~ 10 40 –10 41 erg s -1 , the effective limit of our survey. The constructed hard X-ray luminosity function has a canonical, smoothly broken power-law shape in the range $40 40$ is $(1.4\pm 0.3)\times 10^{39}$ erg s -1 Mpc -3 (17–60 keV). We demonstrate that the spectral shape and amplitude of the CXB are consistent with the simple scenario in which the N H distribution of AGN (for a given $L_{\rm hx}/L_\ast(z)$ ratio) has not changed significantly since $z\sim 1.5$, while the AGN luminosity function has experienced pure luminosity evolution.