skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: EVOLUTION OF THE CROSS-CORRELATION AND TIME LAG OF 4U 1735-44 ALONG THE BRANCHES

Abstract

We analyze the cross-correlation function between the soft and hard X-rays of atoll source 4U 1735-44 with RXTE data, and find anti-correlated soft and hard time lags of about a hecto-second. In the island state, the observations do not show any obvious correlations, and most observations of the banana branch show a positive correlation. However, anti-correlations are detected in the upper banana branch. These results are different from those of Z-sources (Cyg X-2, GX 5-1), where anti-correlations are detected in the horizontal branch and upper normal branch. In this case, the lag timescales of both this atoll and Z-sources are found to be similar, at a magnitude of several tens to hundreds of seconds. As a comparison, it is noted that anti-correlated lags lasting thousands of seconds have been reported from several black hole candidates in their intermediate states. In addition, for an observation containing four segments that show positive or anti-correlation, we analyze the spectral evolution with the hybrid model. In the observation, the anti-correlation is detected at the highest flux. The fitting results show that the Comptonized component is not the lowest at the highest flux, which suggests that the anti-correlation corresponds to the transition between the softmore » and hard states. Finally, we compare the corresponding results of atoll source 4U 1735-44 with those observed in Z-sources and black hole candidates, and the possible origins of the anti-correlated time lags are discussed.« less

Authors:
; ; ; ; ; ;  [1]; ;  [2];  [3]
  1. Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
  2. Particle Astrophysics Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)
  3. Astronomy Department, Beijing Normal University, Beijing 100875 (China)
Publication Date:
OSTI Identifier:
22136567
Resource Type:
Journal Article
Journal Name:
Astronomical Journal (New York, N.Y. Online)
Additional Journal Information:
Journal Volume: 146; Journal Issue: 3; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1538-3881
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; CORRELATION FUNCTIONS; HARD X RADIATION; INTERMEDIATE STATE; MATHEMATICAL EVOLUTION

Citation Formats

Yajuan, Lei, Haotong, Zhang, Chengmin, Zhang, Hailong, Yuan, Yiqiao, Dong, Yongheng, Zhao, Yanxia, Zhang, Jinlu, Qu, Liming, Song, Dehua, Wang, and Yin Hongxing, E-mail: leiyjcwmy@163.com. EVOLUTION OF THE CROSS-CORRELATION AND TIME LAG OF 4U 1735-44 ALONG THE BRANCHES. United States: N. p., 2013. Web. doi:10.1088/0004-6256/146/3/60.
Yajuan, Lei, Haotong, Zhang, Chengmin, Zhang, Hailong, Yuan, Yiqiao, Dong, Yongheng, Zhao, Yanxia, Zhang, Jinlu, Qu, Liming, Song, Dehua, Wang, & Yin Hongxing, E-mail: leiyjcwmy@163.com. EVOLUTION OF THE CROSS-CORRELATION AND TIME LAG OF 4U 1735-44 ALONG THE BRANCHES. United States. https://doi.org/10.1088/0004-6256/146/3/60
Yajuan, Lei, Haotong, Zhang, Chengmin, Zhang, Hailong, Yuan, Yiqiao, Dong, Yongheng, Zhao, Yanxia, Zhang, Jinlu, Qu, Liming, Song, Dehua, Wang, and Yin Hongxing, E-mail: leiyjcwmy@163.com. 2013. "EVOLUTION OF THE CROSS-CORRELATION AND TIME LAG OF 4U 1735-44 ALONG THE BRANCHES". United States. https://doi.org/10.1088/0004-6256/146/3/60.
@article{osti_22136567,
title = {EVOLUTION OF THE CROSS-CORRELATION AND TIME LAG OF 4U 1735-44 ALONG THE BRANCHES},
author = {Yajuan, Lei and Haotong, Zhang and Chengmin, Zhang and Hailong, Yuan and Yiqiao, Dong and Yongheng, Zhao and Yanxia, Zhang and Jinlu, Qu and Liming, Song and Dehua, Wang and Yin Hongxing, E-mail: leiyjcwmy@163.com},
abstractNote = {We analyze the cross-correlation function between the soft and hard X-rays of atoll source 4U 1735-44 with RXTE data, and find anti-correlated soft and hard time lags of about a hecto-second. In the island state, the observations do not show any obvious correlations, and most observations of the banana branch show a positive correlation. However, anti-correlations are detected in the upper banana branch. These results are different from those of Z-sources (Cyg X-2, GX 5-1), where anti-correlations are detected in the horizontal branch and upper normal branch. In this case, the lag timescales of both this atoll and Z-sources are found to be similar, at a magnitude of several tens to hundreds of seconds. As a comparison, it is noted that anti-correlated lags lasting thousands of seconds have been reported from several black hole candidates in their intermediate states. In addition, for an observation containing four segments that show positive or anti-correlation, we analyze the spectral evolution with the hybrid model. In the observation, the anti-correlation is detected at the highest flux. The fitting results show that the Comptonized component is not the lowest at the highest flux, which suggests that the anti-correlation corresponds to the transition between the soft and hard states. Finally, we compare the corresponding results of atoll source 4U 1735-44 with those observed in Z-sources and black hole candidates, and the possible origins of the anti-correlated time lags are discussed.},
doi = {10.1088/0004-6256/146/3/60},
url = {https://www.osti.gov/biblio/22136567}, journal = {Astronomical Journal (New York, N.Y. Online)},
issn = {1538-3881},
number = 3,
volume = 146,
place = {United States},
year = {Sun Sep 15 00:00:00 EDT 2013},
month = {Sun Sep 15 00:00:00 EDT 2013}
}