The X-ray spectral evolution in X-ray binaries and its application to constrain the black hole mass of ultraluminous X-ray sources

	The X-ray spectral evolution in X-ray binaries and its application to constrain the black hole mass of ultraluminous X-ray sources
	Wu, Qingwen 1; Gu, Minfeng2,3,4
刊名	ASTROPHYSICAL JOURNAL
	2008-07-20
卷号	682 期号:1 页码:212-217
关键词	accretion accretion disks black hole physics X-rays : binaries X-rays : galaxies
英文摘要	We investigate the relationship between the hard X-ray photon index Gamma and the Eddington ratio [ xi = L(X)( 0:5-25 keV)/L(Edd)] in six X-ray binaries (XRBs) with well-constrained black hole masses and distances. We find that different XRBs follow different anticorrelations between Gamma and xi when xi is less than a critical value, while Gamma and xi generally follow the same positive correlation when xi is larger than the critical value. The anticorrelation and the positive correlation may suggest that they are in different accretion modes ( e. g., radiatively inefficient accretion flow [RIAF] and standard disk). We fit both correlations with the linear least-squares method for individual sources, from which the cross point of two fitted lines is obtained. Although the anticorrelation varies from source to source, the cross points of all sources roughly converge to the same point with small scatter (log xi = -2.1 +/- 0.2, Gamma = 1.5 +/- 0.1), which may correspond to the transition point between RIAF and standard accretion disk. Motivated by the observational evidence for the similarity of the X-ray spectral evolution of ultraluminous X-ray sources (ULXs) to that of XRBs, we then constrain the black hole masses for seven ULXs, assuming that their X-ray spectral evolution is similar to that of XRBs and that their Eddington ratios are less than 1. We find that the BH masses of these seven luminous ULXs are around 104 M(circle dot), which are typical for intermediate-mass BHs ( IMBHs). Our results are generally consistent with the BH masses constrained from the timing properties ( e. g., break frequency) or the model fitting with a multicolor disk.
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	ACTIVE GALACTIC NUCLEI ; ADVECTION-DOMINATED ACCRETION ; NOVA MUSCAE 1991 ; SLIM-DISK MODEL ; XMM-NEWTON ; STATE TRANSITIONS ; NEARBY GALAXIES ; ENERGY-DISTRIBUTIONS ; SEYFERT-GALAXIES ; OUTBURST DECAY
收录类别	SCI
语种	英语
WOS记录号	WOS:000257834000017
内容类型	期刊论文
源URL	[http://119.78.226.72/handle/331011/19335]
专题	上海天文台_星系宇宙学重点实验室
作者单位	1.Korean Astron & Space Sci Inst, Int Ctr Astrophys, Taejon 305348, South Korea 2.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China 3.SHAO, JOINGC, Shanghai 200030, Peoples R China 4.USTC, Shanghai 200030, Peoples R China
推荐引用方式 GB/T 7714	Wu, Qingwen,Gu, Minfeng. The X-ray spectral evolution in X-ray binaries and its application to constrain the black hole mass of ultraluminous X-ray sources[J]. ASTROPHYSICAL JOURNAL,2008,682(1):212-217.
APA	Wu, Qingwen,&Gu, Minfeng.(2008).The X-ray spectral evolution in X-ray binaries and its application to constrain the black hole mass of ultraluminous X-ray sources.ASTROPHYSICAL JOURNAL,682(1),212-217.
MLA	Wu, Qingwen,et al."The X-ray spectral evolution in X-ray binaries and its application to constrain the black hole mass of ultraluminous X-ray sources".ASTROPHYSICAL JOURNAL 682.1(2008):212-217.