The Nature of the Hard X-Ray Background Sources: Optical, Near-Infrared, Submillimeter, and Radio Properties
The Nature of the Hard X-Ray Background Sources: Optical, Near-Infrared, Submillimeter, and Radio Properties
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硬 X 射线背景源的性质：光学、近红外、亚毫米和无线电特性
DOI：
10.1086/318742
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
E. Richards
中科院分区：
文献类型：
--
作者：
A. Barger;L. Cowie;L. Cowie;R. Mushotzky;E. Richards
根据钱德拉最近的观测，在2-10 keV能量范围内，至少60%的X射线背景现在被分解为离散源。在这里，我们提出了深光学，近红外，亚毫米，和20厘米（无线电）的图像，以及高品质的光谱，一个完整的样本的20个源选择躺在一个2-10千电子伏以上的流量为3.8 × 10-15尔格cm-2 s-1的深钱德拉观测的夏威夷深测量场SSA 13。13个I < 23.5的星系的红移在0.1到2.6之间。两个是类星体，五个显示活动星系核（AGN）的签名，六个是z < 1.5 luminous bulge-dominated galaxies whose spectra show no obvious optical AGN signatures. The seven spectroscopically unidentified I >23.5源的颜色与z = 1.5-3的演化早期星系一致。只有一个硬X射线源是显着检测在超深亚毫米波地图;从亚毫米波的射电流量比，我们估计在1.2-2.4范围内的毫米红移。剩下的19个硬X射线源中没有一个在亚毫米级被单独探测到。这些结果可能反映了这样一个事实，即用SCUBA获得的850 μm通量极限与模糊活动星系核的预期通量相当接近。硬X射线源的集合贡献了大约10%的河外亚毫米波长背景光。从亚毫米波和无线电数据，我们得到的辐射热远红外光度。硬X射线源的辐射热远红外与2-10 keV光度的平均比值约为60，类似于当地被遮蔽的活动星系核。对于亚毫米波段的光源样本，同样的比率超过了1100;这表明它们的远红外光主要是由星星形成产生的。我们的数据显示，明亮的硬X射线源在以膨胀为主的光学发光星系中很常见，在任何给定的时间都有大约10%的人口显示出活动。我们使用我们测量的辐射热修正与2-10 keV的河外背景光来推断超大质量黑洞的生长。即使有很高的吸积辐射效率（λ = 0.1），黑洞的质量密度也可以与当地的黑洞质量密度相媲美。
With recent Chandra observations, at least 60% of the X-ray background in the 2–10 keV energy range is now resolved into discrete sources. Here we present deep optical, near-infrared, submillimeter, and 20 cm (radio) images, as well as high-quality optical spectra, of a complete sample of 20 sources selected to lie above a 2–10 keV flux of 3.8 × 10-15 ergs cm-2 s-1 in a deep Chandra observation of the Hawaii Deep Survey Field SSA13. The 13 galaxies with I < 23.5 have redshifts in the range 0.1 to 2.6. Two are quasars, five show active galactic nucleus (AGN) signatures, and six are z < 1.5 luminous bulge-dominated galaxies whose spectra show no obvious optical AGN signatures. The seven spectroscopically unidentified I > 23.5 sources have colors that are consistent with evolved early galaxies at z = 1.5–3. Only one hard X-ray source is significantly detected in an ultradeep submillimeter map; from the submillimeter to radio flux ratio we estimate a millimetric redshift in the range 1.2–2.4. None of the remaining 19 hard X-ray sources is individually detected in the submillimeter. These results probably reflect the fact that the 850 μm flux limits obtainable with SCUBA are quite close to the expected fluxes from obscured AGNs. The ensemble of hard X-ray sources contribute about 10% of the extragalactic background light at submillimeter wavelengths. From the submillimeter and radio data we obtain bolometric far-infrared luminosities. The hard X-ray sources have an average ratio of bolometric far-infrared to 2–10 keV luminosity of about 60, similar to that of local obscured AGNs. The same ratio for a sample of submillimeter-selected sources is in excess of 1100; this suggests that their far-infrared light is primarily produced by star formation. Our data show that luminous hard X-ray sources are common in bulge-dominated optically luminous galaxies, with about 10% of the population showing activity at any given time. We use our measured bolometric corrections with the 2–10 keV extragalactic background light to infer the growth of supermassive black holes. Even with a high radiative efficiency of accretion (ϵ = 0.1), the black hole mass density required to account for the observed light is comparable to the local black hole mass density.