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arXiv 2103.16448astro-ph.GA
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类星体宽发射线随光学/紫外周期性的变化对超大质量双星黑洞解释的检验

Variation of Broad Emission Lines from QSOs with Optical/UV Periodicity to Test the Interpretation of Supermassive Binary Black Holes

Xiang Ji, Youjun Lu, Junqiang Ge, Changshuo Yan, Zihao Song

摘要:

周期性类星体被认为是超大质量双黑洞(BBH)的宿主,它们的光学/紫外周期性被解释为由次级黑洞(BH)周围盘的连续辐射的多普勒增强(DB)效应或内禀吸积率变化引起的。然而,没有发现其他明确的证据来证实这种BBH解释。在本文中,我们研究了宽发射线(BEL)的连续变化的两个BH方案下,这些类星体的响应,并检查它们是否可以相互区分,并从一个单一的BH系统。我们假设一个简单的环双星宽线区(BLR)模型,兼容BLR大小估计,与标准的$Γ$分布的BLR云。我们发现,由于(1)次级BH的位置变化和(2)DB效应,如果显着的,和/或内在的变化,这是显着不同的情况下,一个单一的BH系统的BBH场景下,BELs可能会显着和周期性的变化。对于两种BBH情景,BELs对由DB效应或内禀速率变化引起的(表观)连续变化的响应也存在显著差异,这主要是因为DB效应具有沿次级BH运动方向的优先方向,而内禀变化引起的优先方向则没有。来自不同场景的BEL响应的这种差异可能提供一种鲁棒的方法来区分对周期类星体的不同解释,并在这些系统中识别BBH(如果有的话)。

英文摘要:

Periodic quasars have been suggested to host supermassive binary black holes (BBHs) in their centers, and their optical/UV periodicities are interpreted as caused by either the Doppler-boosting (DB) effect of continuum emission from the disk around the secondary black hole (BH) or intrinsic accretion rate variation. However, no other definitive evidence has been found to confirm such a BBH interpretation(s). In this paper, we investigate the responses of broad emission lines (BELs) to the continuum variations for these quasars under two BBH scenarios, and check whether they can be distinguished from each other and from that of a single BH system. We assume a simple circumbinary broad-line region (BLR) model, compatible with BLR size estimates, with a standard $Γ$ distribution of BLR clouds. We find that BELs may change significantly and periodically under the BBH scenarios due to (1) the position variation of the secondary BH and (2) the DB effect, if significant, and/or intrinsic variation, which is significantly different from the case of a single BH system. For the two BBH scenarios, the responses of BELs to (apparent) continuum variations, caused by the DB effect or intrinsic rate variation, are also significantly different from each other, mainly because the DB effect has a preferred direction along the direction of motion of the secondary BH, while that due to intrinsic variation does not. Such differences in the responses of BELs from different scenarios may offer a robust way to distinguish different interpretations of periodic quasars and to identify BBHs, if any, in these systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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