Cross-correlations between soft and hard light curves depending on luminosity in the transient neutron star XTE J1701-462

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	Cross-correlations between soft and hard light curves depending on luminosity in the transient neutron star XTE J1701-462
	Wang YN(王亚楠); Wang, YN; Lei, YJ; Ding, GQ; Qu, JL; Ge, MY; Zhang, CM; Chen, L; Ma, X;; Qu JL(屈进禄)
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2014
卷号	440 期号:4 页码:3726-3737
关键词	accretion X-rays: binaries stars: individual: XTE J1701-462 accretion discs
英文摘要	Using all the observations from Rossi X-ray Timing Explorer for the accreting neutron star XTE J1701-462, we carry out a systematic study of the cross-correlation function between its soft and hard light curves. Over the entire outburst, XTE J1701-462 evolves from super-Eddington luminosities to quiescence and shows both Z and atoll behaviours. Following previous work, we divide the outburst into five intervals: one Cyg-like interval, three Sco-like intervals and one atoll interval, according to their different behaviours in the corresponding colour-colour diagrams (CCDs). With cross-correlation analyses, anti-correlation, positive and ambiguous correlations are found in the different intervals in this source. Both anti-correlated soft and hard time lags are detected, where hard lags mean that the hard photons lag behind the soft ones and soft lags mean the reverse. In the Cyg-like interval, anti-correlations are presented in the hard vertex and upper normal branch (NB) and positive correlations dominate the horizontal branch (HB) and lower NB. In the first two Sco-like intervals, anti-correlations are detected first and most of them are found in the HB and/or upper NB, while positive correlations are mostly detected in the lower NB and flaring branch (FB). In the following interval, i.e. the third Sco-like interval, anti-correlations occur on the upper FB and positive correlations are mainly distributed in the lower FB. The different intervals correspond to various luminosities; therefore, the position of anti-correlations in the CCD might depend on the luminosity. It is noted that, in the Cyg-like interval, positive correlations dominate the HB, which is not consistent with the behaviour of the Cyg-like Z sources GX 5-1 and Cyg X-2, the HBs of which host ambiguous correlations and anti-correlations. Hence, for comparison with GX 5-1, we analyse the spectra of the HB and the hard vertex of the Cyg-like interval. The fitting results show that, in contrast to GX 5-1, the ratio of hard emission to soft emission basically remains unvaried from the HB to the hard vertex, which might result in positive correlation. Additionally, we compare the spectra of the third Sco-like interval with atoll source 4U 1735-44 and find that their spectral evolution along the tracks in the CCD is similar, indicating that in this interval XTE J1701-462 could approach an atoll source. The truncated disc model might be responsible for the detected time lags in XTE J1701-462; the possible origins of anti-correlated hard and soft time lags are also discussed.
学科主题	Astronomy & Astrophysics
收录类别	SCI
WOS记录号	WOS:000336213800063
公开日期	2016-05-03
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/225191]
专题	高能物理研究所_粒子天体物理中心
推荐引用方式 GB/T 7714	Wang YN,Wang, YN,Lei, YJ,et al. Cross-correlations between soft and hard light curves depending on luminosity in the transient neutron star XTE J1701-462[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2014,440(4):3726-3737.
APA	王亚楠.,Wang, YN.,Lei, YJ.,Ding, GQ.,Qu, JL.,...&马想.(2014).Cross-correlations between soft and hard light curves depending on luminosity in the transient neutron star XTE J1701-462.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,440(4),3726-3737.
MLA	王亚楠,et al."Cross-correlations between soft and hard light curves depending on luminosity in the transient neutron star XTE J1701-462".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 440.4(2014):3726-3737.