SPECTRAL ENERGY DISTRIBUTIONS OF QSOs AT z > 5: COMMON ACTIVE GALACTIC NUCLEUS-HEATED DUST AND OCCASIONALLY STRONG STAR-FORMATION
SPECTRAL ENERGY DISTRIBUTIONS OF QSOs AT z > 5: COMMON ACTIVE GALACTIC NUCLEUS-HEATED DUST AND OCCASIONALLY STRONG STAR-FORMATION
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DOI：
10.1088/0004-637x/785/2/154
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发表时间：
2014-02
期刊：
影响因子：
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通讯作者：
C. Leipski;K. Meisenheimer;F. Walter;U. Klaas;H. Dannerbauer;G. D. Rosa;Xiaohui Fan;M. Haas
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作者：
C. Leipski;K. Meisenheimer;F. Walter;U. Klaas;H. Dannerbauer;G. D. Rosa;Xiaohui Fan;M. Haas
我们展示了 69 个 QSO 在 z > 5 处的光谱能量分布 (SED)，涵盖 0.1 μm 至 ∼80 μm 的静止帧波长范围，并以新的 Spitzer 和 Herschel 观测为中心。 Spitzer 的 QSO 检测率非常高（在 λrest ≲ 4 μm 处为 97%），但向赫歇尔波段下降，在 PACS（静止框架中红外）中检测到 30%，在 SPIRE（静止框架远红外；FIR）中检测到 15%。我们对 Herschel 检测到的物体进行多分量 SED 拟合，并确认为了匹配观察到的 SED，块状环面模型需要由热 (∼1300 K) 分量来补充，并且在具有显着 FIR 发射的情况下，还需要冷 (∼50 K) 分量。在 FIR 探测到的情况下，冷成分的光度约为 1013 L☉，很可能是因恒星形成而被加热。根据 SED 拟合，我们还确定活动星系核 (AGN) 尘埃与吸积盘的光度比随着紫外/光学光度而下降。热（~1300 K）尘埃的发射在我们的样本中很常见，这表明核尘埃在红移 6 的发光 QSO 中无处不在。然而，与光学发射相比，大约 15% 的物体在近红外区域显得发光不足，并且似乎缺乏（但并非没有）热尘埃。在我们的完整样本中，赫歇尔检测到的 QSO 位于 LUV/opt 和 LNIR 的高光度端，并且在 Hα 和 Lyα 中显示出较低的等效宽度 (EW)。在 Hα EW 的分布中，根据斯皮策光度法测定，高红移 QSO 与低红移 AGN 几乎没有差异。
We present spectral energy distributions (SEDs) of 69 QSOs at z > 5, covering a rest frame wavelength range of 0.1 μm to ∼80 μm, and centered on new Spitzer and Herschel observations. The detection rate of the QSOs with Spitzer is very high (97% at λrest ≲ 4 μm), but drops toward the Herschel bands with 30% detected in PACS (rest frame mid-infrared) and 15% additionally in the SPIRE (rest frame far-infrared; FIR). We perform multi-component SED fits for Herschel-detected objects and confirm that to match the observed SEDs, a clumpy torus model needs to be complemented by a hot (∼1300 K) component and, in cases with prominent FIR emission, also by a cold (∼50 K) component. In the FIR-detected cases the luminosity of the cold component is of the order of 1013 L☉ which is likely heated by star formation. From the SED fits we also determine that the active galactic nucleus (AGN) dust-to-accretion disk luminosity ratio declines with UV/optical luminosity. Emission from hot (∼1300 K) dust is common in our sample, showing that nuclear dust is ubiquitous in luminous QSOs out to redshift 6. However, about 15% of the objects appear under-luminous in the near infrared compared to their optical emission and seem to be deficient in (but not devoid of) hot dust. Within our full sample, the QSOs detected with Herschel are found at the high luminosity end in LUV/opt and LNIR and show low equivalent widths (EWs) in Hα and in Lyα. In the distribution of Hα EWs, as determined from the Spitzer photometry, the high-redshift QSOs show little difference to low-redshift AGN.