Long-term Spectral Variability of the Ultraluminous X-Ray Source Holmberg IX X–1

doi:10.3847/1538-4357/aa8eeb

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	Long-term Spectral Variability of the Ultraluminous X-Ray Source Holmberg IX X–1
	Jithesh,V.2; Misra,Ranjeev 1; Wang,Zhongxiang 2
刊名	The Astrophysical Journal
	2017-11-07
卷号	849 期号:2
关键词	accretion, accretion disks black hole physics X-rays: binaries X-rays: individual (Holmberg IX X–1)
ISSN号	0004-637X
DOI	10.3847/1538-4357/aa8eeb
英文摘要	Abstract We investigate the long-term spectral variability in the ultraluminous X-ray source Holmberg IX X–1. By analyzing the data from 8 Suzaku and 13 XMM-Newton observations conducted between 2001 and 2015, we perform a detailed spectral modeling for all spectra with simple models and complex physical models. We find that the spectra can be well explained by a disk-plus-thermal-Comptonization model. Applying this model, we unveil correlations between the X-ray luminosity ( L X ) and the spectral parameters. One particular correlation is the statistically significant positive correlation between L X and the photon index (Γ), while at the high luminosities of > 2 × 10 40 erg s ? 1 , the source becomes marginally hard, which results in a change in the slope of the Γ – L X correlation. Similar variability behavior is observed in the optical depth of the source around L X ～ 2 × 10 40 erg s ? 1 as the source becomes more optically thick. We consider the scenario that a corona covers the inner part of the disk, and the correlations can be explained as being driven by the variability of seed photons from the disk input into the corona. On the basis of the disk-corona model, we discuss the physical processes that are possibly indicated by the variability of the spectral parameters. Our analysis reveals the complex variability behavior of Holmberg IX X–1 and the variability mechanism is likely related to the geometry of the X-ray-emitting regions.
语种	英语
出版者	The American Astronomical Society
WOS记录号	IOP:0004-637X-849-2-AA8EEB
内容类型	期刊论文
源URL	[http://119.78.226.72/handle/331011/32089]
专题	中国科学院上海天文台
作者单位	1.Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007, India 2.Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China; jithesh@shao.ac.cn
推荐引用方式 GB/T 7714	Jithesh,V.,Misra,Ranjeev,Wang,Zhongxiang. Long-term Spectral Variability of the Ultraluminous X-Ray Source Holmberg IX X–1[J]. The Astrophysical Journal,2017,849(2).
APA	Jithesh,V.,Misra,Ranjeev,&Wang,Zhongxiang.(2017).Long-term Spectral Variability of the Ultraluminous X-Ray Source Holmberg IX X–1.The Astrophysical Journal,849(2).
MLA	Jithesh,V.,et al."Long-term Spectral Variability of the Ultraluminous X-Ray Source Holmberg IX X–1".The Astrophysical Journal 849.2(2017).