X-ray spectra of hot accretion flows

	X-ray spectra of hot accretion flows
	Niedzwiecki, Andrzej 1; Xie, Fu-Guo 2; Stepnik, Agnieszka 1
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2014-09-11
卷号	443 期号:2 页码:1733-1747
关键词	accretion black hole physics X-rays: binaries X-rays: galaxies accretion discs
通讯作者	谢富国
英文摘要	We study radiative properties of hot accretion flows in a general relativistic model with an exact treatment of global Comptonization, developed in our recent works. We note a strong dependence of electron temperature on the strength of magnetic field and we clarify that the underlying mechanism involves the change of the flow structure, with more strongly magnetized flows approaching the slab geometry more closely. We find that the model with thermal synchrotron radiation being the main source of seed photons agrees with the spectral index versus Eddington ratio relation observed in black hole transients below 1 per cent of the Eddington luminosity, L-Edd, and models with a weak direct heating of electrons (small delta) are more consistent with observations. Models with large delta predict slightly too soft spectra, furthermore, they strongly overpredict electron temperatures at similar to 0.01 L-Edd. The low-luminosity spectra, at less than or similar to 0.001 L-Edd, deviate from a power-law shape in the soft X-ray range, and we note that the first-scattering bump often resembles a thermal like component, with the temperature of a few hundred eV, superimposed on a power-law spectrum. The model with thermal Comptonization of thermal synchrotron radiation does not agree with well-studied AGNs observed below similar to 0.01 L-Edd, for which there is a substantial evidence for the lack of an inner cold disc. This indicates that the model of hot flows powering AGNs should be revised, possibly by taking into account an additional (but internal to the flow) source of seed photons.
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	ADVECTION-DOMINATED ACCRETION ; BLACK-HOLE BINARIES ; ACTIVE GALACTIC NUCLEI ; BROAD-BAND SPECTRUM ; HARD STATE ; LOW/HARD STATE ; XTE J1550-564 ; CYG X-1 ; SEYFERT-GALAXIES ; CIRCINUS GALAXY
收录类别	SCI
语种	英语
WOS记录号	WOS:000340436800063
公开日期	2015-02-14
内容类型	期刊论文
源URL	[http://119.78.226.72//handle/331011/15818]
专题	上海天文台_星系宇宙学重点实验室
作者单位	1.Univ Lodz, Dept Astrophys, PL-90236 Lodz, Poland 2.Chinese Acad Sci, Shanghai Astron Observ, Key Lab Res Galaxies & Cosmol, Shanghai 200030, Peoples R China
推荐引用方式 GB/T 7714	Niedzwiecki, Andrzej,Xie, Fu-Guo,Stepnik, Agnieszka. X-ray spectra of hot accretion flows[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2014,443(2):1733-1747.
APA	Niedzwiecki, Andrzej,Xie, Fu-Guo,&Stepnik, Agnieszka.(2014).X-ray spectra of hot accretion flows.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,443(2),1733-1747.
MLA	Niedzwiecki, Andrzej,et al."X-ray spectra of hot accretion flows".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 443.2(2014):1733-1747.