Insight-HXMT observations of jet-like corona in a black hole X-ray binary MAXI J1820+070

A black hole X-ray binary produces hard X-ray radiation from its corona and disk when the accreting matter heats up. During an outburst, the disk and corona co-evolves with each other. However, such an evolution is still unclear in both its geometry and dynamics. Here we report the unusual decrease of the reflection fraction in MAXI J1820+070, which is the ratio of the coronal intensity illuminating the disk to the coronal intensity reaching the observer, as the corona is observed to contrast during the decay phase. We postulate a jet-like corona model, in which the corona can be understood as a standing shock where the material flowing through. In this dynamical scenario, the decrease of the reflection fraction is a signature of the corona's bulk velocity. Our findings suggest that as the corona is observed to get closer to the black hole, the coronal material might be outflowing faster.

Bei You, Yuoli Tuo, Chengzhe Li, Wei Wang, Shuang-Nan Zhang, Shu Zhang, Mingyu Ge, Chong Luo, Bifang Liu, Weimin Yuan, Zigao Dai, Jifeng Liu, Erlin Qiao, Chichuan Jin, Zhu Liu, Bozena Czerny, Qingwen Wu, Qingcui Bu, Ce Cai, Xuelei Cao, Zhi Chang, Gang Chen, Li Chen, Tianxiang Chen, Yibao Chen, Yong Chen, Yupeng Chen, Wei Cui, Weiwei Cui, Jingkang Deng, Yongwei Dong, Yuanyuan Du, Minxue Fu, Guanhua Gao, He Gao, Min Gao, Yudong Gu, Ju Guan, Chengcheng Guo, Dawei Han, Yue Huang, Jia Huo, Shumei Jia, Luhua Jiang, Weichun Jiang, Jing Jin, Yongjie Jin, Lingda Kong, Bing Li, Chengkui Li, Xiaohua Liang, Jinyuan Liao, Congzhan Liu, Guoqing Liu, Hongwei Liu, Xiaojing Liu, Zhengwei Li, Xiaohua Liang, Jinyuan Liao, Congzhan Liu, Guoqing Liu, Hongwei Liu, Xiaojing Liu, Yinong Liu, Bo Lu, Fangjun Lu, Xuefeng Lu, Qi Luo, Tao Luo, Xiang Ma, Bin Meng, Yi Nang, Jianyin Nie, Ge Ou, Jinlu Qu, Na Sai, Rencheng Shang, Liming Song, Xinying Song, Liang Sun, Ying Tan, Lian Tao, Chen Wang, Guofeng Wang, Juan Wang, Lingjun Wang, Wenshuai Wang, Yusa Wang, Xiangyang Wen, Baiyang Wu, Bobing Wu, Mei Wu, Guangcheng Xiao, Shuo Xiao, Shaolin Xiong, Yupeng Xu, Jiawei Yang, Sheng Yang, Yanji Yang, Qibin Yi, Qianqing Yin, Yuan You, Aimei Zhang, Chengmo Zhang, Fan Zhang, Hongmei Zhang, Juan Zhang, Tong Zhang, Wanchang Zhang, Wei Zhang, Wenzhao Zhang, Yi Zhang, Yifei Zhang, Yongjie Zhang, Yue Zhang, Zhao Zhang, Ziliang Zhang, Haisheng Zhao, Xiaofan Zhao, Shijie Zheng, Dengke Zhou, Jianfeng Zhou, Yuxuan Zhu, Yue Zhu