THE DISK EVAPORATION MODEL FOR THE SPECTRAL FEATURES OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

	THE DISK EVAPORATION MODEL FOR THE SPECTRAL FEATURES OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI
	Qiao, Erlin1 ; Liu, B. F.1; Panessa, Francesca 2; Liu, J. Y.3,4
刊名	ASTROPHYSICAL JOURNAL
	2013-11-10
卷号	777 期号:2
关键词	accretion, accretion disks black hole physics galaxies: active X-rays: galaxies
英文摘要	Observations show that the accretion flows in low-luminosity active galactic nuclei probably have a two-component structure with an inner, hot, optically thin, advection-dominated accretion flow (ADAF) and an outer, truncated, cool, optically thick accretion disk. As shown by Taam et al., the truncation radius as a function of mass accretion rate is strongly affected by including the magnetic field within the framework of disk evaporation model, i.e., an increase in the magnetic field results in a smaller truncation radius of the accretion disk. In this work, we calculate the emergent spectrum of an inner ADAF + an outer truncated accretion disk around a supermassive black hole based on the prediction by Taam et al.. It is found that an increase in the magnetic field from beta = 0.8 to beta = 0.5 (with magnetic pressure p(m) = B-2/8 pi = (1 - beta)p(tot), p(tot) = p(gas) + p(m)) results in a factor of similar to 8.7 increase in the luminosity from the truncated accretion disk. Meanwhile, results of the peak emission of the truncated accretion disk shift toward a a factor of similar to 5 higher frequency. We found that the equipartition of gas pressure to magnetic pressure, i.e., beta = 0.5, failed to explain the observed anti-correlation between (L2-10) (keV)/L-Edd and the bolometric correction kappa(2-10 keV) (with kappa(2-10 keV) = L-bol/L2-10 keV). The emergent spectra for larger values of beta = 0.8 or beta = 0.95 can explain the observed L2-10 keV/L-Edd-kappa(2-10 keV) correlation. We argue that in the disk evaporation model, the electrons in the corona are assumed to be heated only by a transfer of energy from the ions to electrons via Coulomb collisions, which is reasonable for accretion with a lower mass accretion rate. Coulomb heating is the dominated heating mechanism for the electrons only if the magnetic field is strongly sub-equipartition, which is roughly consistent with observations.
收录类别	SCI
语种	英语
WOS记录号	WOS:000326218800021
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/6035]
专题	国家天文台_空间科学研究部
作者单位	1.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China 2.Ist Astrofis & Planetol Spaziali Roma IAPS, INAF, I-00133 Rome, Italy 3.Chinese Acad Sci, Yunnan Observ, Kunming 650011, Peoples R China 4.Chinese Acad Sci, Key Lab Struct & Evolut Celestial Objects, Kunming 650011, Peoples R China
推荐引用方式 GB/T 7714	Qiao, Erlin,Liu, B. F.,Panessa, Francesca,et al. THE DISK EVAPORATION MODEL FOR THE SPECTRAL FEATURES OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI[J]. ASTROPHYSICAL JOURNAL,2013,777(2).
APA	Qiao, Erlin,Liu, B. F.,Panessa, Francesca,&Liu, J. Y..(2013).THE DISK EVAPORATION MODEL FOR THE SPECTRAL FEATURES OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI.ASTROPHYSICAL JOURNAL,777(2).
MLA	Qiao, Erlin,et al."THE DISK EVAPORATION MODEL FOR THE SPECTRAL FEATURES OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI".ASTROPHYSICAL JOURNAL 777.2(2013).