期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 324, 期 3, 页码 653-658出版社
BLACKWELL SCIENCE LTD
DOI: 10.1046/j.1365-8711.2001.04344.x
关键词
galaxies : active; galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies
We assembled a sample of Seyfert 1 galaxies, quasi-stellar objects (QSOs) and low-luminosity active galactic nuclei (LLAGNs) observed by ASCA, the central black hole masses of which have been measured. We found that the X-ray variability (which is quantified by the 'excess variance' sigma (2)(rms)) is significantly anti-correlated with the central black hole mass, and it is likely that a linear relationship of sigma (2)(rms) proportional to M-bh(-1) exists. It can be interpreted that the short time-scale X-ray variability is caused by some global coherent variations in the X-ray emission region, which is scaled by the size of the central black hole. Hence the central black hole mass is the driving parameter of the previously established relation between X-ray variability and luminosity. Our findings favour the hypothesis that the narrow-line Seyfert 1 galaxies and QSOs harbour smaller black holes than the broad-line objects, and can also easily explain the observational fact that high-redshift QSOs have greater variability than local AGNs at a given luminosity. Further investigations are needed to confirm our findings, and a large sample X-ray variability investigation can give constraints on the physical mechanisms and evolution of AGNs.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据