The Evolution of the Broadband Temporal Features Observed in the Black-hole Transient MAXI J1820+070 with Insight-HXMT

Wang, Yanan; Ji, Long; Zhang, S.; Mendez, Mariano; Qu, J.; Maggi, Pierre; Ge, M.; Qiao, Erlin; Tao, L.; Zhang, S.; Altamirano, Diego; Zhang, L.; Ma, X.; Lu, F.; Li, T.; Huang, Y.; Zheng, S.; Chen, Y.; Chang, Z.; Tuo, Y.; Gungor, CAN; Song, L.; Xu, Y.; Cao, X.; Chen, Y.; Liu, C.; Bu, Q.; Cai, C.; Chen, G.; Chen, L.; Chen, T.; Chen, Y.; Cui, W.; Cui, W.; Deng, J.; Dong, Y.; Du, Y.; Fu, M.; Gao, G.; Gao, H.; Gao, M.; Gu, Y.; Guan, J.; Guo, C.; Han, D.; Huo, J.; Jia, S.; Jiang, L.; Jiang, W.; Jin, J.; Jin, Y.; Kong, L.; Li, B.; Li, C.; Li, G.; Li, M.; Li, W.; Li, X.; Li, X.; Li, X.; Li, Y.; Li, Z.; Liang, X.; Liao, J.; Liu, G.; Liu, H.; Liu, X.; Liu, Y.; Lu, B.; Lu, X.; Luo, Q.; Luo, T.; Meng, B.; Nang, Y.; Nie, J.; Ou, G.; Sai, N.; Shang, R.; Song, X.; Sun, L.; Tan, Y.; Wang, G.; Wang, J.; Wang, W.; Wang, Y.; Wang, Y.; Wen, X.; Wu, B.; Wu, B.; Wu, M.; Xiao, G.; Xiao, S.; Xiong, S.; Yang, J.; Yang, S.; Yang, Y.; Yi, Q.; Yin, Q.; You, Y.; Zhang, A.; Zhang, C.; Zhang, F.; Zhang, H.; Zhang, J.; Zhang, T.; Zhang, W.; Zhang, W.; Zhang, W.; Zhang, Y.; Zhang, Y.; Zhang, Y.; Zhang, Z.; Zhang, Z.; Zhao, H.; Zhao, X.; Zhou, D.; Zhou, J.; Zhuang, R.; Zhu, Y.; Zhu, Y.; Wang, Lingjun

doi:10.3847/1538-4357/ab8db4

The Evolution of the Broadband Temporal Features Observed in the Black-hole Transient MAXI J1820+070 with Insight-HXMT

Wang Y., Ji L., Zhang S. N., Mendez M., Qu J. L., Maggi P., ...More

ASTROPHYSICAL JOURNAL, vol.896, no.1, 2020 (SCI-Expanded, Scopus)

Publication Type: Article / Article
Volume: 896 Issue: 1
Publication Date: 2020
Doi Number: 10.3847/1538-4357/ab8db4
Journal Name: ASTROPHYSICAL JOURNAL
Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, INSPEC, zbMATH, DIALNET
Istanbul University Affiliated: Yes

Abstract

We study the evolution of the temporal properties of MAXI J1820+070 during the 2018 outburst in its hard state from MJD 58,190 to 58,289 with Insight-HXMT in a broad energy band 1-150 keV. We find different behaviors of the hardness ratio, the fractional rms and time lag before and after MJD 58,257, suggesting a transition occurred around this point. The observed time lags between the soft photons in the 1-5 keV band and the hard photons in higher energy bands, up to 150 keV, are frequency-dependent: the time lags in the low-frequency range, 2-10 mHz, are both soft and hard lags with a timescale of dozens of seconds but without a clear trend along the outburst; the time lags in the high-frequency range, 1-10 Hz, are only hard lags with a timescale of tens of milliseconds; they first increase until around MJD 58,257 and decrease after this date. The high-frequency time lags are significantly correlated to the photon index derived from the fit to the quasi-simultaneous NICER spectrum in the 1-10 keV band. This result is qualitatively consistent with a model in which the high-frequency time lags are produced by Comptonization in a jet.