Exploring Changes in Quasar Spectral Energy Distributions across C iv Parameter Space
Exploring Changes in Quasar Spectral Energy Distributions across C iv Parameter Space
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DOI：
10.3847/1538-4357/ac6a5d
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
A. Rivera;G. Richards;S. Gallagher;Trevor V. McCaffrey;A. Rankine;P. Hewett;O. Shemmer
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作者：
A. Rivera;G. Richards;S. Gallagher;Trevor V. McCaffrey;A. Rankine;P. Hewett;O. Shemmer
我们研究了1378个类星体的UV/X射线性质，以便将经验关联与支配类星体的物理机制的理论模型联系起来，这些物理机制是质量和吸积率的函数。当(1)使用CIV宽发射线当量宽度(EQW)和从光学/紫外光谱的高信噪比重建中计算的蓝移(相对于系统)值，以及(2)根据它们的UV/X射线光谱斜率去除预期被吸收的类星体时，这些关联的清晰度得到了提高。除了使用传统的C IV参数空间度量C IV EQW和BlueShift之外，我们还定义了沿最佳拟合多项式曲线的“C IV∥距离”，该多项式曲线包含了来自两个C IV参数的信息。我们发现，C IV∥距离与光学对X射线的斜率、αOX和宽线He II方程QW都是线性相关的，这是已知的光谱能量分布指标，但不需要X射线或高光谱分辨率的UV观测来计算。Civ∥距离可能比Civ EQW或蓝移更好地指示由L/L Edd参数化的质量加权吸积率，因为这些关系在极值时会破裂。相反，与X射线能量指数(Γ)只有微弱的相关性，这是L/L的另一个EDD指标。我们没有发现在垂直于CIV距离的方向上的X射线或光学趋势，这些趋势可以用来揭示吸积盘、风或日冕结构的差异，这些结构可能会加宽CIV EQW-蓝移分布。这些数据没有追踪到的另一个参数(如金属丰度)必须发挥作用。
We examine the UV/X-ray properties of 1378 quasars in order to link empirical correlations to theoretical models of the physical mechanisms dominating quasars as a function of mass and accretion rate. The clarity of these correlations is improved when (1) using C iv broad emission line equivalent width (EQW) and blueshift (relative to systemic) values calculated from high signal-to-noise ratio reconstructions of optical/UV spectra and (2) removing quasars expected to be absorbed based on their UV/X-ray spectral slopes. In addition to using the traditional C iv parameter space measures of C iv EQW and blueshift, we define a “C iv ∥ distance” along a best-fit polynomial curve that incorporates information from both C iv parameters. We find that the C iv ∥ distance is linearly correlated with both the optical-to-X-ray slope, α ox, and broad-line He ii EQW, which are known spectral energy distribution indicators, but does not require X-ray or high spectral resolution UV observations to compute. The C iv ∥ distance may be a better indicator of the mass-weighted accretion rate, parameterized by L/L Edd, than the C iv EQW or blueshift alone, as those relationships are known to break down at the extrema. Conversely, there is only a weak correlation with the X-ray energy index (Γ), an alternate L/L Edd indicator. We find no X-ray or optical trends in the direction perpendicular to the C iv distance that could be used to reveal differences in accretion disk, wind, or corona structure that could be widening the C iv EQW–blueshift distribution. A different parameter (such as metallicity) not traced by these data must come into play.