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

Bei You,Gang Li,Weichun Jiang,Liming Song,Yanguo Li,Xian Li,Xiaofan Zhao,Wenshuai Wang,Chen Wang,Shu Zhang,Yuxuan Zhu,Shuo Xiao,Li Chen,Yusa Wang,C Cai ,F J Lu ,Yu-Peng Chen ,J Guan ,Luhua Jiang,T Luo ,L D Kong ,Yue Zhang,Min Gao,Xu-Fang Li ,Wei Zhang,Tong Zhang,Xiaojing Liu,J Y Nie ,Wanchang Zhang,Wei Cui,Fan Zhang,Cong‐Zhan Liu ,Yi Zhang,He Gao,Y L Tuo ,Q B Yi ,Bo Lü ,Y Nang ,Xiang-Yang Wen ,Mei‐Hwan Wu ,Ming-Yu Ge ,Shi-Jie Zheng ,Wenzhao Zhang,X H Liang ,Xiaobo Li,Yibao Chen,Zhu Li ,Y D Gu ,Gang Chen,Qingwen Wu,Yanji Yang,Cheng Luo ,Chengmo Zhang,Tianxiang Chen,Yongjie Zhang,Wei Li,Zhao Zhang,Bin Meng,B B Wu ,M X Fu ,Yong Chen,G H Gao ,Yupeng Xu,Shuang‐Nan Zhang ,S L Xiong ,D K Zhou ,Hongmei Zhang,Guoqing Liu,Liang Sun,Jiawei Yang,Q C Bu ,Jing Jin,Yifei Zhang,Mao-Shun Li ,Weimin Yuan,Aimei Zhang,Q Luo ,Yinong Liu,G Ou ,Hongwei Liu,X L Cao ,J L Qu ,Q Q Yin ,Zhengwei Li,Y You ,B Li ,X F Lu ,G C Xiao ,Juan Zhang,B Czerny ,Erlin Qiao,Juan Wang,Yongwei Dong,C Jin ,Y Huang ,Lian Tao,H S Zhao ,N Sai ,S Jia ,Ti-Pei Li ,Guofeng Wang,Bobing Wu,J K Deng ,Ziliang Zhang,S Yang ,Haiqiang Jia ,R C Shang ,Y Y Du ,L J Wang ,X Y Song ,Bifang Liu,Chengzhe Li,Ying Tan,Z G Dai ,Chengcheng Guo,Jianfeng Zhou,Wei Wang,Danxiang Han ,Yan Jin ,Zhi Chang,Xiang Ma,Weiwei Cui,Jifeng Liu,J Y Liao ,Cheng-Kui Li ,Yajun Zhu

doi:10.1038/s41467-021-21169-5

Abstract

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.

Highlights

A black hole X-ray binary produces hard X-ray radiation from its corona and disk when the accreting matter heats up
We found that all spectra of MAXI J1820 + 070 in the first outburst can be approximately characterized by an asymptotic power law with a cutoff at high energy ≤100 keV
The emissivity profile is roughly flattened with the index q1 < 1.0 within the broken radius Rbr ~ 20–60RISCO

Summary

Introduction

A black hole X-ray binary produces hard X-ray radiation from its corona and disk when the accreting matter heats up. 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. A black hole (BH) X-ray binary usually displays transition between hard and soft states, according to the spectral properties of its radiation[1,2,3,4]. In the soft state with the photon index Γ > 2, the observed radiation is characterized by a strong (disk) blackbody component below ~10 keV and a weak, high-energy tail of ~25% of the total bolometric luminosity[2,5,6,7,8]. MAXI J1820 + 070 rapidly rose from 2018-03-14

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Conclusion