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arXiv 1202.3137astro-ph.CO
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AGN的60个月全天BAT巡天及附近AGN的各向异性

The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN

M. Ajello, D. M. Alexander, J. Greiner, G. M. Madejski, N. Gehrels, D. Burlon

摘要:

超过10 keV的测量是对活动星系核(AGN)进行无偏普查的最佳资源之一。我们提出了60个月的观测结果的硬X射线天空与雨燕/BAT。在这段时间内,BAT在全天巡天中探测到(在15- 55千电子伏波段)720个源,其中428个与活动星系核有关,大部分都在附近。我们的样本具有可忽略不计的不完整性和统计的\sim 2倍以上类似完整的活动星系核。我们的样本包含(至少)15个真正的康普顿厚度AGN和3个可能的候选者。康普顿厚度的活动星系核代表了~5%的活动星系核样品检测到高于15千电子伏。我们使用BAT数据集,以完善的LogN-LogS的AGN这是非常重要的,现在NuSTAR准备发射,对评估AGN的贡献宇宙X射线背景的确定。我们表明,LogN-LogS的AGN选择以上10千电子伏,现在建立了~10%的精度。导出了康普顿厚度活动星系核的光度函数,并对去吸收光度大于2 $\times10^{42}$,erg s $^{-1}$的天体测得空间密度为7.9 $^{+4.1}_{-2.9}\times10^{-5}$,Mpc $^{-3}$.由于BAT活动星系核大多是局域的,它们使我们能够研究活动星系核在邻近宇宙中的空间分布,而不考虑吸收。我们发现AGN的浓度在空间上与当地(<85 Mpc)宇宙中最大的物质聚集相吻合。有一些证据表明,在这些密集区域的方向上,塞弗特2型天体的比例大于平均水平。

英文摘要:

Surveys above 10 keV represent one of the the best resources to provide an unbiased census of the population of Active Galactic Nuclei (AGN). We present the results of 60 months of observation of the hard X-ray sky with Swift/BAT. In this timeframe, BAT detected (in the 15--55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGN, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of \sim2 larger over similarly complete sets of AGN. Our sample contains (at least) 15 bona-fide Compton-thick AGN and 3 likely candidates. Compton-thick AGN represent a ~5% of AGN samples detected above 15 keV. We use the BAT dataset to refine the determination of the LogN--LogS of AGN which is extremely important, now that NuSTAR prepares for launch, towards assessing the AGN contribution to the cosmic X-ray background. We show that the LogN--LogS of AGN selected above 10 keV is now established to a ~10% precision. We derive the luminosity function of Compton-thick AGN and measure a space density of 7.9$^{+4.1}_{-2.9}\times10^{-5}$\,Mpc$^{-3}$ for objects with a de-absorbed luminosity larger than 2$\times10^{42}$\,erg s$^{-1}$. As the BAT AGN are all mostly local, they allow us to investigate the spatial distribution of AGN in the nearby Universe regardless of absorption. We find concentrations of AGN that coincide spatially with the largest congregations of matter in the local (<85 Mpc) Universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.

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