A characteristic optical variability time scale in astrophysical accretion disks
A characteristic optical variability time scale in astrophysical accretion disks
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DOI：
10.1126/science.abg9933
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发表时间：
2021-08
期刊：
影响因子：
56.9
通讯作者：
C. J. Burke;Yue Shen;O. Blaes;C. Gammie;K. Horne;Yan-Fei Jiang;Xin Liu;I. McHardy;C. Morgan;S. Scaringi;Qian Yang
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作者：
C. J. Burke;Yue Shen;O. Blaes;C. Gammie;K. Horne;Yan-Fei Jiang;Xin Liu;I. McHardy;C. Morgan;S. Scaringi;Qian Yang
活动星系的变化时间尺度活动星系核包含一个被吸积盘包围的超大质量黑洞(SMBH)。当磁盘材料落向SMBH时，它被加热到足以发出光学光。Burke等人。研究了67个活动星系样本中的这种光发射如何随时间变化(见Lira和Arevalo的透视图)。他们观察到了随着SMBH质量的变化而变化的时间特征。这些结果阐明了吸积盘内的物理过程，并提供了一种从光学变率观测中估计SMBH质量的方法。科学，abg9933，本期第789页；另见abk3451，第734页活动星系核的光学可变性提供了一种估计超大质量黑洞质量的方法。活动星系核中超大质量黑洞周围的吸积盘产生紫外线和光学波长的连续辐射。吸积流中的物理过程导致了这种排放在广泛的时间尺度上的随机变化。我们测量了在67个活动星系核中观测到的光学连续谱变率和变率功率谱平坦的特征时间尺度。我们发现了这一时间尺度与超大质量黑洞整个质量范围内的黑洞质量之间的关联。这一时间尺度与标准吸积盘理论中紫外线发射半径处的预期热时间尺度是一致的。吸积白矮星位于这种关联附近，这表明所有吸积盘都有一个共同的过程。
Variability time scales in active galaxies Active galactic nuclei contain a supermassive black hole (SMBH) surrounded by an accretion disk. As disk material falls toward the SMBH, it heats up enough to emit optical light. Burke et al. investigated how such optical emission varies over time in a sample of 67 active galaxies (see the Perspective by Lira and Arevalo). They observed a characteristic variability in timing that scaled with the SMBH mass. The results elucidate the physical processes within accretion disks and provide a method to estimate SMBH mass from optical variability observations. Science, abg9933, this issue p. 789; see also abk3451, p. 734 Optical variability of active galactic nuclei provides a method to estimate supermassive black hole masses. Accretion disks around supermassive black holes in active galactic nuclei produce continuum radiation at ultraviolet and optical wavelengths. Physical processes in the accretion flow lead to stochastic variability of this emission on a wide range of time scales. We measured the optical continuum variability observed in 67 active galactic nuclei and the characteristic time scale at which the variability power spectrum flattens. We found a correlation between this time scale and the black hole mass extending over the entire mass range of supermassive black holes. This time scale is consistent with the expected thermal time scale at the ultraviolet-emitting radius in standard accretion disk theory. Accreting white dwarfs lie close to this correlation, suggesting a common process for all accretion disks.