Ya-Juan Lei, Hao-Tong Zhang, Cheng-Min Zhang, Jin-Lu Qu, Hai-Long Yuan, Yi-Qiao Dong, Yong-Heng Zhao, De-Hua Wang, Hong-Xing Yin, Li-Ming Song
We analyze the cross-correlation function between the soft and hard X-rays of atoll source 4U 1735-44 with RXTE data, and find the anti-correlated soft and hard time lags of about hecto-second. On the island state, the observations do not show any obvious correlations, and most observations of banana branch show positive correlation. However, the anti-correlations are detected on the upper banana branch. These results are different from those of Z sources (Cyg X-2, GX 5-1), where the anti-correlation is detected in the low luminosity states, then the lag timescales of both this atoll and Z sources are found to be similar, at the magnitude of several tens to hundreds of seconds. As a comparison, it is noted that the anti-correlated lags of thousand-second have been reported from the several black hole candidates in their intermediate states. Finally, we compare the correspondent results of atoll source 4U 1735-44 with those observed in black hole candidates and Z sources, and the possible origins of the anti-correlated time lags are discussed.
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http://arxiv.org/abs/1301.5725
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