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A Chandra survey of z ≥ 4.5 quasars
Monthly Notices of the Royal Astronomical Society ( IF 4.8 ) Pub Date : 2021-04-13 , DOI: 10.1093/mnras/stab1042
Jiang-Tao Li 1 , Feige Wang 2 , Jinyi Yang 2 , Joel N Bregman 1 , Xiaohui Fan 2 , Yuchen Zhang 1
Affiliation  

X-ray observations provide a unique probe of the accretion disc corona of supermassive black holes (SMBHs). In this paper, we present a uniform Chandra X-ray data analysis of a sample of 152 z ≥ 4.5 quasars. We firmly detect 46 quasars of this sample in 0.5–2 keV above 3σ and calculate the upper limits of the X-ray flux of the remaining. We also estimate the power-law photon index of the X-ray spectrum of 31 quasars. 24 of our sample quasars are detected in the FIRST or NVSS radio surveys; all of them are radio-loud. We statistically compare the X-ray properties of our z ≥ 4.5 quasars to other X-ray samples of active galactic nuclei (AGNs) at different redshifts. The relation between the rest-frame X-ray luminosity and other quasar parameters, such as the bolometric luminosity, UV luminosity, or SMBH mass, shows large scatters. These large scatters can be attributed to the narrow luminosity range at the highest redshift, the large measurement error based on relatively poor X-ray data, and the inclusion of radio-loud quasars in the sample. The LX–LUV relationship is significantly sublinear. We do not find a significant redshift evolution of the LX–LUV relation, expressed either in the slope of this relation, or the departure of individual AGNs from the best-fitting αOX–LUV relation (ΔαOX). The median value of the X-ray photon index is Γ ≈ 1.79, which does not show redshift evolution from z = 0 to z ∼ 7. The X-ray and UV properties of the most distant quasars could potentially be used as a standard candle to constrain cosmological models. The large scatter of our sample on the Hubble diagram highlights the importance of future large unbiased deep X-ray and radio surveys in using quasars in cosmological studies.

中文翻译:

z ≥ 4.5 类星体的钱德拉调查

X 射线观测提供了对超大质量黑洞 (SMBH) 吸积盘日冕的独特探测。在本文中,我们对 152 z ≥ 4.5 类星体样本进行了统一的钱德拉 X 射线数据分析。我们在 3σ 以上 0.5-2 keV 范围内牢固地检测到该样本的 46 个类星体,并计算剩余的 X 射线通量的上限。我们还估计了 31 个类星体的 X 射线光谱的幂律光子指数。我们的 24 个样本类星体在 FIRST 或 NVSS 无线电调查中被检测到;所有这些都是无线电响亮的。我们将 z ≥ 4.5 类星体的 X 射线特性与不同红移的活动星系核 (AGN) 的其他 X 射线样本进行了统计比较。静止坐标系 X 射线光度与其他类星体参数之间的关系,例如辐射热光度、紫外光度或 SMBH 质量,显示出较大的散射。这些大的散射可归因于最高红移处的窄光度范围、基于相对较差的 X 射线数据的大测量误差以及样品中包含无线电响亮的类星体。LX-LUV 关系明显是次线性的。我们没有发现 LX-LUV 关系的显着红移演变,表现为该关系的斜率,或单个 AGN 与最佳拟合 αOX-LUV 关系(ΔαOX)的偏离。X 射线光子指数的中值是 Γ ≈ 1.79,它没有显示从 z = 0 到 z ∼ 7 的红移演变。最遥远类星体的 X 射线和紫外线特性可能被用作标准烛光约束宇宙学模型。
更新日期:2021-04-13
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