CG X-1: An Eclipsing Wolf–Rayet ULX in the Circinus Galaxy

doi:10.3847/1538-4357/ab16e7

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	CG X-1: An Eclipsing Wolf–Rayet ULX in the Circinus Galaxy
	Qiu,Yanli 9,10; Soria,Roberto 7,8,9,10; Wang,Song 10; Wiktorowicz,Grzegorz 9,10; Liu,Jifeng 6,9,10; Bai,Yu 10; Bogomazov,Alexey 5; Stefano,Rosanne Di 4; Walton,Dominic J.3; Xu,Xiaojie 1,2
刊名	The Astrophysical Journal
	2019-05-24
卷号	877 期号:1
关键词	accretion, accretion disks stars: Wolf–Rayet X-rays: binaries X-rays: individual (CGX-1)
ISSN号	0004-637X
DOI	10.3847/1538-4357/ab16e7
英文摘要	Abstract We investigated the time-variability and spectral properties of the eclipsing X-ray source Circinus Galaxy X-1 (GG X-1), using Chandra, XMM-Newton and ROSAT. We phase-connected the light curves observed over 20 yr, and we obtained a best-fitting period P?=?(25,970.0?±?0.1) s?≈?7.2 hr, and a period derivative P ˙ / P = ( 10.2 ± 4.6 ) × 10 ? 7 yr?1. The X-ray light curve shows asymmetric eclipses, with sharp ingresses and slow, irregular egresses. The eclipse profile and duration vary substantially from cycle to cycle. We show that the X-ray spectra are consistent with a power-law-like component, which is absorbed by neutral and ionized Compton-thin material, and by a Compton-thick, partial-covering medium, which is responsible for the irregular dips. The high X-ray/optical flux ratio rules out the possibility that CG X-1 is a foreground Cataclysmic Variable. In agreement with previous studies, we conclude that it is the first example of a compact ultraluminous X-ray source fed by a Wolf–Rayet star or stripped Helium star. Its unocculted luminosity varies between ≈4?×?1039 erg s?1 and ≈3?×?1040 erg s?1. Both the donor star and the super-Eddington compact object drive powerful outflows. We suggest that the occulting clouds are produced in the wind–wind collision region and in the bow shock in front of the compact object. Among the rare sample of Wolf–Rayet X-ray binaries, CG X-1 is an exceptional target for studies of supercritical accretion and close binary evolution; it is also a likely progenitor of gravitational wave events.
语种	英语
出版者	The American Astronomical Society
WOS记录号	IOP:0004-637X-877-1-AB16E7
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/28882]
专题	中国科学院国家天文台
作者单位	1.Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210023, People's Republic of China 2.School of Astronomy and Space Science, Nanjing University, Nanjing 210023, People's Republic of China 3.Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 4.Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 5.M.V. Lomonosov Moscow State University, P.K. Sternberg Astronomical Institute, 13, Universitetskij Prospect, Moscow, 119991, Russia 6.WHU-NAOC Joint Center for Astronomy, Wuhan University, Wuhan, Hubei 430072, People’s Republic of China 7.Sydney Institute for Astronomy, School of Physics A28, The University of Sydney, Sydney, NSW 2006, Australia 8.International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845, Australia 9.School of Astronomy and Space Sciences, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China 10.Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ylqiu@bao.ac.cn, rsoria@nao.cas.cn, jfliu@bao.ac.cn
推荐引用方式 GB/T 7714	Qiu,Yanli,Soria,Roberto,Wang,Song,et al. CG X-1: An Eclipsing Wolf–Rayet ULX in the Circinus Galaxy[J]. The Astrophysical Journal,2019,877(1).
APA	Qiu,Yanli.,Soria,Roberto.,Wang,Song.,Wiktorowicz,Grzegorz.,Liu,Jifeng.,...&Xu,Xiaojie.(2019).CG X-1: An Eclipsing Wolf–Rayet ULX in the Circinus Galaxy.The Astrophysical Journal,877(1).
MLA	Qiu,Yanli,et al."CG X-1: An Eclipsing Wolf–Rayet ULX in the Circinus Galaxy".The Astrophysical Journal 877.1(2019).