论文标题
在没有高红移AGN的情况下：高红移的超质量黑洞人口的增长很少
On the Absence of High-Redshift AGNs: Little Growth in the Supermassive Black Hole Population at High Redshifts
论文作者
论文摘要
我们在7毫秒Chandra深地上野外X射线图像的深中心（离轴角<5.7'）区域中搜索高红移（Z> 4.5）X射线AGN。我们从直接X射线检测中编译了初始候选样本。然后，我们通过使用具有高空间分辨率NIR/miR（HST 1.6微米和Spitzer 4.5微米）和亚毫升（Alma 850微米）观察的预选样品的预选样品，更深入地探测X射线数据。 NIR/MIR和亚毫米预选前的组合使我们能够找到具有广泛的灰尘特性和光谱能量分布（SED）的X射线源。我们使用从光学到亚毫米计的SED来确定先前的光度红移是否合理。只有五个可能的Z> 5 X射线AGN，所有这些都可能位于较低的红移。如果它们确实位于高红移中，那么两个是Compton-Thick-thick Agn，而三个是ALMA 850微米来源。我们发现（i）（i）X射线AGN的数量密度在高红移下迅速下降，（ii）检测到的AGN对Z> 5处的光电发电量没有显着贡献，并且（iii）测得的X射线光密度在Z = 5-10上的X射线光密度在这个黑洞中很小的生长在此黑洞中很少，在这个黑洞中很少，在Black Hole质量范围内，X射线密度很小。
We search for high-redshift (z>4.5) X-ray AGNs in the deep central (off-axis angle <5.7') region of the 7 Ms Chandra Deep Field-South X-ray image. We compile an initial candidate sample from direct X-ray detections. We then probe more deeply in the X-ray data by using pre-selected samples with high spatial resolution NIR/MIR (HST 1.6 micron and Spitzer 4.5 micron) and submillimeter (ALMA 850 micron) observations. The combination of the NIR/MIR and submillimeter pre-selections allows us to find X-ray sources with a wide range of dust properties and spectral energy distributions (SEDs). We use the SEDs from the optical to the submillimeter to determine if previous photometric redshifts were plausible. Only five possible z>5 X-ray AGNs are found, all of which might also lie at lower redshifts. If they do lie at high redshifts, then two are Compton-thick AGNs, and three are ALMA 850 micron sources. We find that (i) the number density of X-ray AGNs is dropping rapidly at high redshifts, (ii) the detected AGNs do not contribute significantly to the photoionization at z>5, and (iii) the measured X-ray light density over z=5-10 implies a very low black hole accretion density with very little growth in the black hole mass density in this redshift range.
