Low redshift AGN in the Hamburg/ESO survey - I. The local AGN luminosity function
Low redshift AGN in the Hamburg/ESO survey - I. The local AGN luminosity function
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DOI：
10.1051/0004-6361/200912730
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发表时间：
2009-09
影响因子：
6.5
通讯作者：
A. Schulze;L. Wisotzki;B. Husemann
中科院分区：
文献类型：
--
作者：
A. Schulze;L. Wisotzki;B. Husemann
我们提出了一个确定的本地（z <$0）光度函数的光学选择1型（宽线）活动星系核。我们的主要资源是汉堡/ESO巡天（HES），它提供了300多个红移z MBJ >-26的光学明亮活动星系核的明确样本，这两个测量是紧密相关的。由此产生的活动星系核光度函数（AGNLF）是符合一个单一的幂律，也考虑到在窄红移范围内的数量密度演化的影响。我们将我们的AGNLF与Hao et al.（2005 a，AJ，129，1795）的低光度Seyfert 1星系的Hα光度函数进行了比较，发现两者之间存在一个平滑的过渡，在重叠区域有很好的一致性。从HES和SDSS样本的组合，我们构建了一个单一的本地AGNLF跨越超过4个数量级的光度。它只有轻微的曲率，可以很好地描述为双幂律，暗端的斜率指数为-2.0，亮端为-2.8。我们预测的本地AGNLF在软X射线域，并比较这与最近的文献数据。匹配的质量很大程度上取决于所采用的光学到X射线光度的转换，并且对于近似恒定的光学/X射线比率是最好的。我们还将局域AGNLF与在更高红移下获得的结果进行了比较，并发现了光度依赖演化的强有力证据，在这个意义上，亮度在MB − 19附近的AGN在局域宇宙中与z = 1.5时一样常见。这支持了首次从X射线选择的活动星系核样品中发现的“活动星系核缩小”图像。
We present a determination of the local (z ≈ 0) luminosity function of optically selected type 1 (broad-line) active galactic nuclei. Our primary resource is the Hamburg/ESO survey (HES), which provides a well-defined sample of more than 300 optically bright AGN with redshifts z MBJ > −26), the two measures are tightly correlated. The resulting AGN luminosity function (AGNLF) is consistent with a single power law, also when considering the effects of number density evolution within the narrow redshift range. We compared our AGNLF with the Hα luminosity function of lower luminosity Seyfert 1 galaxies by Hao et al. (2005a, AJ, 129, 1795) and found a smooth transition between both, with excellent agreement in the overlapping region. From the combination of HES and SDSS samples we constructed a single local AGNLF spanning more than 4 orders of magnitude in luminosity. It shows only mild curvature which can be well described as a double power law with slope indices of −2.0 for the faint end and −2.8 for the bright end. We predicted the local AGNLF in the soft X-ray domain and compared this to recent literature data. The quality of the match depends strongly on the adopted translation of optical to X-ray luminosities and is best for an approximately constant optical/X-ray ratio. We also compared the local AGNLF with results obtained at higher redshifts and find strong evidence for luminosity-dependent evolution, in the sense that AGN with luminosities around MB �− 19 are as common in the local universe as they were at z = 1.5. This supports the “AGN downsizing” picture first found from X-ray selected AGN samples.