Constraints on black hole spins with a general relativistic accretion disk corona model

作     者：Bei You Xin-Wu Cao Ye-Fei Yuan 

作者机构：Key Laboratory for Research in Galaxies and CosmologyShanghai Astronomical ObservatoryChinese Academy of SciencesShanghai 200030China Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China University of Chinese Academy of SciencesBeijing 100049China 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2016年第16卷第4期

页      面：15-26页

核心收录：

学科分类：0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 070401[理学-天体物理] 0704[理学-天文学] 0825[工学-航空宇航科学与技术] 

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11173043,11121062,11233006,11073020,11373056 and 11473054) the Fundamental Research Funds for the Central Universities(WK2030220004) the CAS/SAFEA International Partnership Program for Creative Research Teams(KJCX2-YW-T23) Shanghai Municipality 

主　　题：quasars： accretion disk    X ray： corona    black hole physics    galaxies： active 

摘      要：The peaks in the spectra of the accretion disks surrounding massive black holes in quasars are in the far-UV or soft X-ray band, which are usually not observed. However, in the disk corona model, soft photons from the disk are Comptonized to high energy in the hot corona, and the hard X-ray spectra （lu- minosity and spectral shape） contain information on the incident spectra from the disk. The values of black hole spin parameter a. are inferred from the spectral fitting, which are spread over a large range, ~ -0.94 to 0.998. We find that the inclination angles and mass accretion rates are well determined by the spectral fitting, but the results are sensitive to the accuracy of black hole mass estimates. No tight constraints on the black hole spins are achieved, if the uncertainties in black hole mass measurements are a factor of four, which are typical for the single-epoch reverberation mapping method. Recently, the accuracy of black hole mass measurement has been significantly improved to 0.2 - 0.4 dex with the velocity resolved reverber- ation mapping method. The black hole spin can be well constrained if the mass measurement accuracy is 50%. In the accretion disk corona scenario, a fraction of power dissipated in the disk is transported into the corona, and therefore the accretion disk is thinner than a bare disk for the same mass accretion rate, because the radiation pressure in the disk is reduced. We find that the thin disk approximation, H/R ≤0. 1, is still valid if 0.3 〈 m 〈 0.5, provided half of the dissipated power is radiated in the corona above the disk.