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arXiv 1306.3521astro-ph.CO
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类星体中基于CIV的黑洞质量估计的修正

Rehabilitating CIV-based black hole mass estimates in quasars

J. C. Runnoe, M. S. Brotherton, Zhaohui Shang, M. A. DiPompeo

摘要:

目前,使用CIV 1549线产生与Hb质量估计一致的黑洞质量估计的能力是不确定的,这在很大程度上是由于两条线的速度线宽度测量之间的分歧。Hb和CIV之间的这种差异源于这样一个事实,即基于宽线区域被维里化的假设,在单历元标度关系中以相同的方式处理两个线轮廓,即使非维里化的发射分量在CIV线中通常是显著的,而在Hb线中不存在或较弱。利用85个红移在z=0.03-1.4范围内的光学明亮类星体的准同步光学和紫外光谱,我们沿着恢复黑洞质量估计的CIV线的道路迈出了重要的一步。我们发现,CIV和Hb之间的速度线宽的残差与SiIV+OIV] 1400与CIV的峰值流量比显著相关。利用这种关系,我们开发了一个处方估计黑洞质量的紫外光谱同意更好地与基于Hb的群众比传统的CIV群众。在我们的样本中,Hb和CIV质量之间的离散度最初为0.43 dex,当使用我们的处方时,离散度降低至0.33 dex。SiIV+OIV] 1400与CIV的峰值通量比是通常被称为“本征向量1”的光谱特性套件的紫外指示器,因此CIV和Hb黑洞质量之间的散射的减少基本上是由于去除了基于CIV的质量中的本征向量1偏差。

英文摘要:

Currently, the ability to produce black hole mass estimates using the CIV 1549 line that are consistent with Hb mass estimates is uncertain, due in large part to disagreement between velocity line width measurements for the two lines. This discrepancy between Hb and CIV arises from the fact that both line profiles are treated the same way in single-epoch scaling relationships based on the assumption that the broad-line region is virialized, even though a non-virialized emission component is often significant in the CIV line and absent or weak in the Hb line. Using quasi-simultaneous optical and ultra-violet spectra for a sample of 85 optically bright quasars with redshifts in the range z=0.03-1.4, we present a significant step along the path to rehabilitating the CIV line for black hole mass estimates. We show that the residuals of velocity line width between CIV and Hb are significantly correlated with the peak flux ratio of SiIV+OIV] 1400 to CIV. Using this relationship, we develop a prescription for estimating black hole masses from the ultra-violet spectrum that agree better with Hb-based masses than the traditional CIV masses. The scatter between Hb and CIV masses is initially 0.43 dex in our sample and is reduced to 0.33 dex when using our prescription. The peak flux ratio of SiIV+OIV] 1400 to CIV is an ultraviolet indicator of the suite of spectral properties commonly known as "Eigenvector 1", thus the reduction in scatter between CIV and Hb black hole masses is essentially due to removing an Eigenvector 1 bias in CIV-based masses.

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