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arXiv · 2207.14048

An Insight-HXMT view of the mHz quasi-regular modulation phenomenon in the black hole X-ray binary 4U 1630-47

Abstract

Here we report the spectral-timing results of the black hole X-ray binary 4U 1630-47 during its 2021 outburst using observations from the Hard X-ray Modulation Telescope. Type-C quasi-periodic oscillations (QPOs) in 1.6--4.2 Hz and quasi-regular modulation (QRM) near 60 mHz are detected during the outburst. The mHz QRM has a fractional rms of 10%--16% in the 8--35 keV energy band with a Q factor (frequency/width) of 2--4. Benefiting from the broad energy band of hxmt, we study the energy dependence of the 60 mHz QRM in 1--100 keV for the first time. We find that the fractional rms of the mHz QRM increases with photon energy, while the time lags of the mHz QRM are soft and decrease with photon energy. Fast recurrence of the mHz QRM, in a timescale of less than one hour, has been observed during the outburst. During this period, the corresponding energy spectra moderately change when the source transitions from the QRM state to the non-QRM state. The QRM phenomena also shows a dependence with the accretion rate. We suggest that the QRM could be caused by an unknown accretion instability aroused from the corona.

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Zi-Xu Yang, Liang Zhang, Yue Huang, Qingcui Bu, Zhen Zhang, He-Xin Liu, Wei Yu, Peng-Ju Wang, Q. C. Zhao, L. Tao, Jin-Lu Qu, Shu Zhang, Shuang-Nan Zhang, Liming Song, Fangjun Lu, Xuelei Cao, Li Chen, Ce Cai, Zhi Chang, Tianxian Chen, Yong Chen, Yupeng Chen, Yibao Chen, Weiwei Cui, Guoqiang Ding, Yuanyuan Du, GuanHua Gao, He Gao, Mingyu Ge, Yudong Gu, Ju Guan, Chengcheng Guo, Dawei Han, Jia Huo, Shumei Jia, Weichun Jiang, Jing Jin, Lingda Kong, Bing Li, Gang Li, Wei Li, Xian Li, Xufang Li, Zhengwei Li, Chengkui Li, Lin Lin, Congzhan Liu, Tipei Li, Xiaobo Li, Xiaohua Liang, Jinyuan Liao, Hongwei Liu, Xiaojing Liu, Xuefeng Lu, Qi Luo, Tao Luo, Binyuan Ma, Ruican Ma, Xiang Ma, Bin Meng, Yi Nang, Jianyin Nie, Ge Ou, Xiaoqin Ren, Na Sai, Xinying Song, Liang Sun, Ying Tan, Youli Tuo, Chen Wang, Wenshuai Wang, Lingjun Wang, Yusa Wang, Jieshuang Wang, Xiangyang Wen, Bobing Wu, Baiyang Wu, Mei Wu, Shuo Xiao, Yupeng Xu, Shaolin Xiong, Sheng Yang, Yanji Yang, Qibin Yi, Qianqing Yin, Yuan You, Bing Zhang, Fan Zhang, Hongmei Zhang, Juan Zhang, Wanchang Zhang, Wei Zhang, Binbin Zhang, Peng Zhang, Yifei Zhang, Yuanhang Zhang, Haisheng Zhao, Xiaofan Zhao, Shijie Zheng, Dengke Zhou. 2022-07-28. An Insight-HXMT view of the mHz quasi-regular modulation phenomenon in the black hole X-ray binary 4U 1630-47. https://doi.org/10.3847/1538-4357%2Fac84d6

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