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1. Insight-HXMT Views Her X-1: Probing the Dependence of the Cyclotron Line Energy on Flux and Time

Author

G. C. Xiao, R. Staubert, L. Ji, M. Y. Ge, Q. Z. Liu, J. L. Qu, S. Zhang, S. N. Zhang, J. Z. Yan, J. Li, Q. C. Bu, Y. L. Tuo, H. X. Liu, and Z. X. Yang

Subjects
Accretion, X-ray binary stars, Astrophysics, QB460-466
Abstract

Recent observations of Her X-1 with NuSTAR (as well as with INTEGRAL, Swift, and Astrosat) have provided evidence that the nearly 20 yr-long decay of the cyclotron line energy since ∼1994 has ended and that a stable value has replaced the decay. Using the observations of the Hard X-ray Modulation Telescope (Insight-HXMT) performed between 2017 July and 2020 February, we analyze the spectra of Her X-1 in its main-on state, focusing on tracing the evolution of cyclotron line energy. While our analysis of eight main-on observations with Insight-HXMT (two in coordination with NuSTAR) shows significant differences with the results of NuSTAR, two earlier findings are confirmed: the positive correlation between the cyclotron line energy and the X-ray flux (source luminosity) and the constancy of the flux-normalized cyclotron line energy during 2017–2020—albeit with significant uncertainty about the absolute value.

Published
2023
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2. The 2018 failed outburst of H 1743 – 322: Insight-HXMT, NuSTAR, and NICER views

Author

P J Wang, L D Kong, Y P Chen, S Zhang, S N Zhang, R Soria, L Ji, J L Qu, Y Huang, L Tao, M Y Ge, F J Lu, L Chen, T P Li, Y P Xu, X L Cao, Y Chen, C Z Liu, Q C Bu, C Cai, Z Chang, T X Chen, Y B Chen, W W Cui, Y Y Du, G H Gao, H Gao, Y D Gu, J Guan, C C Guo, D W Han, J Huo, S M Jia, W C Jiang, J Jin, B Li, C K Li, G Li, W Li, X Li, X B Li, X F Li, Z W Li, X H Liang, J Y Liao, B S Liu, H X Liu, H W Liu, X J Liu, X F Lu, Q Luo, T Luo, R C Ma, X Ma, B Meng, Y Nang, J Y Nie, G Ou, X Q Ren, N Sai, L M Song, X Y Song, L Sun, Y Tan, Y L Tuo, C Wang, L J Wang, W S Wang, Y S Wang, X Y Wen, B Y Wu, B B Wu, M Wu, G C Xiao, S Xiao, S L Xiong, R J Yang, S Yang, Yan Ji Yang, Yi Jung Yang, Q B Yi, Q Q Yin, Y You, F Zhang, H M Zhang, J Zhang, P Zhang, W C Zhang, W Zhang, Y F Zhang, Y H Zhang, H S Zhao, X F Zhao, S J Zheng, Y G Zheng, and D K Zhou

Subjects
Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics
Abstract

We studied the 2018 outburst of the black hole transient H 1743 − 322 with a series of Insight-HXMT, NICER, and NuSTAR observations, covering the 1–120 keV band. With our broad-band X-ray spectral modelling, we confirm that the source remained in the low/hard state throughout the month-long outburst, although it became marginally softer at peak flux. We detected Type-C quasi-periodic oscillations (QPOs) and followed the evolution of their properties. The QPO frequency increased from ∼0.1 to ∼0.4 Hz during the rising phase of the outburst and decreased again in the decline. Continuum X-ray flux, power-law photon index, QPO frequency, and QPO root-mean-square amplitude were positively correlated. The QPO amplitude was slightly higher in the soft X-ray band (typical values of 12–16 per cent, compared with 8–10 per cent in the hard band). Our spectral-timing results shed light on the initial rising phase in the low/hard state, which has rarely been monitored with such high cadence, time resolution, and broad-band coverage. Combining spectral and timing properties, we find that ‘failed’ (hard state only) and ‘successful’ outbursts follow the same initial evolutionary track, although the former class of outburst never reaches the threshold for a transition to softer (thermally dominated) accretion regimes.

Published
2022

3. Line-of-shower trigger method to lower energy threshold for GRB detection using LHAASO-WCDA

Author

C. F. Feng, Bin Zhou, X. L. Ji, R. Lu, H. B. Xiao, J. R. Shi, W. Zeng, Z. H. Wang, Shengxue Zhang, Pak-Hin Thomas Tam, H. C. Li, Jun Liu, H. Y. Jia, B. D'Ettorre Piazzoli, W. X. Wu, Junjie Mao, Y. Q. Guo, Dong Liu, F. Ji, H. R. Wu, Y. J. Wei, Alejandro Sáiz, Oleg Shchegolev, L. Feng, V. Rulev, L. Xue, Xuliang Chen, Xing-Yuan Hou, D. M. Wei, S. Hu, M. L. Chen, Jianeng Zhou, J. Y. Liu, Warit Mitthumsiri, Y. Zhang, Q. An, Y. He, Q. Gao, Ruizhi Yang, X. N. Sun, H. B. Hu, H. Liu, L. Chen, X. G. Wang, S. Q. Xi, J. Fang, X. H. You, Ping Zhou, Z. C. Huang, Y. Z. Li, P. F. Zhang, C. Y. Wu, Hong-Guang Wang, G. M. Xiang, W. Liu, Yu-Lei Chen, Zihuang Cao, X. C. Chang, Z. K. Zeng, Y. J. Bi, H. D. Liu, Y. D. Cheng, Bo Zhang, Y. Zheng, L. Q. Yin, Duo Yan, F. Zheng, Hao Zhou, X. X. Zhou, Q. Yuan, Hefan Li, J. F. Chang, Z. X. Liu, Felix Aharonian, H. N. He, C. D. Gao, Lei Zhao, Q. H. Chen, Youping Li, Y. M. Ye, B. B. Li, Yongchun Wang, Y. D. Cui, Bai Yibing, L. P. Wang, J. B. Zhao, Y. J. Wang, J. Y. Yang, S. Z. Chen, Yunchao Liu, B. Z. Dai, Rong Xu, Z. X. Fan, Z. Y. You, Z. G. Dai, X. F. Wu, He Zhang, S. H. Feng, S. B. Yang, J. J. Xia, W. Gao, S. L. He, Y. P. Wang, B. M. Chen, Fan Yang, A. Masood, Kun Fang, S.H. Chen, Yugang Zhang, H. Cai, Lang Shao, H. Wang, J.W. Xia, L. Z. Zhao, G. C. Xiao, X. X. Zhai, Y. C. Nan, Shi-Qi Hu, X. J. Bi, Z. Li, R. Liu, E. W. Liang, X. Zuo, M. J. Yang, Y. H. Yao, W. L. Li, L. X. Zhang, H. K. Lv, Xufang Li, B. Y. Pang, Zebo Tang, M. H. Gu, Z. Y. Pei, Xuejiao Li, F. R. Zhu, T. L. Chen, Qie Sun, K. J. Zhu, Ying Zhang, H. M. Zhang, J. Chen, H. L. Dai, Y. L. Xin, T. Wen, S. W. Cui, M. Zha, J. C. He, W. H. Huang, L. X. Bai, Binyu Zhao, Yun-Feng Liang, Jixia Li, X. H. Cui, Xinbo He, K. Jiang, X. J. Hu, J. W. Zhang, Li-Sheng Geng, Wenwu Tian, Z. X. Wang, Xiaofei Zhang, David Ruffolo, Yu. V. Stenkin, C. Hou, Z. B. Sun, Shuibin Lin, Lu Zhang, K. Levochkin, Cheng Guang Zhu, X. D. Sheng, Minghao Qi, Houdun Zeng, Jun-Jie Wei, Jia Zhang, Y. A. Han, H. B. Li, Danzengluobu, Rui Zhang, H. C. Song, Linbin Yang, Y. Z. Fan, J. T. Cai, H. H. He, Y. M. Xing, F. Y. Li, D. H. Huang, H. Zhu, Xiang Zhang, M. M. Ge, J. G. Guo, S. R. Zhang, N. Cheng, L. L. Ma, G. H. Gong, J. S. Wang, Cunguo Wang, Shujuan Liu, N. Yin, Y. H. Yu, W. J. Long, Axikegu, Xuelong Wang, P. P. Zhang, Chunlong Li, Minghui Liu, D. Bastieri, Jinyao Liu, Z. G. Yao, X. H. Ma, M. Heller, K. Li, Z. J. Jiang, J. Liu, R. N. Wang, V. I. Stepanov, Jian Wang, Chiming Jin, D.A. Kuleshov, G. G. Xin, M. J. Chen, S. P. Zhao, Y. Y. Guo, Donglian Xu, X. L. Guo, X. J. Dong, Y. K. Hor, T. Montaruli, Y. L. Feng, W. Wang, P. Pattarakijwanich, S. Wu, B. D. Wang, C. X. Liu, Y. W. Bao, X. T. Huang, R. Zhou, L. Y. Wang, D. della Volpe, C. W. Yang, Jun-Hui Fan, Zujian Wang, Q. B. Gou, Qizhi Huang, B. Liu, Bingshui Gao, Xiang-Yu Wang, Tao Zeng, and Bin Ma

Subjects
Physics, Nuclear and High Energy Physics, Cherenkov detector, Astrophysics::High Energy Astrophysical Phenomena, Detector, Astrophysics, law.invention, Air shower, Nuclear Energy and Engineering, Duty cycle, law, Observatory, Gamma-ray burst, Energy (signal processing), Line (formation)
Abstract

Observation of high energy and very high emission from Gamma Ray Bursts (GRBs) is crucial to study the gigantic explosion and the underline processes. With a large field-of-view and almost full duty cycle, the Water Cherenkov Detector Array (WCDA), a sub-array of the Large High Altitude Air Shower Observatory (LHAASO), is appropriate to monitor the very high energy emission from unpredictable transients such as GRBs. Nevertheless, the main issue for an extensive air shower array is the high energy threshold which limits the horizon of the detector. To address this issue a new trigger method is developed in this article to lower the energy threshold of WCDA for GRB observation. The proposed method significantly improves the detection efficiency of WCDA for gamma-rays around the GRB direction at 10-300 GeV. The sensitivity of the WCDA for GRB detection with the new trigger method is estimated. The achieved sensitivity of the quarter WCDA array above 10 GeV is comparable with that of Fermi-LAT. The data analysis process and corresponding fluence upper limit for GRB 190719C is presented as an example.

Published
2021

4. Accretion torque reversals in GRO J1008-57 revealed by Insight-HXMT

Author

Prahlad Epili, ShiJie Zheng, Yuan-Yuan Du, Peng Zhang, W. C. Jiang, Y. M. Tang, T. Luo, C. Z. Liu, S. Yang, Y. B. Chen, Xin Ren, Xufang Li, Gang Li, Cheng-Cheng Guo, Y. J. Yang, N. Sai, W. S. Wang, Wei Wang, Lei Sun, Zhe Chang, W. G. Li, X.W. Ma, L. D. Kong, Q. Luo, Bin Meng, Y. S. Wang, Jin-Yuan Liao, X. L. Cao, Da-Wei Han, Lian Tao, L. Wang, Tianran Chen, Y. G. Zheng, C. Cai, Xiong Li, Yu-Dong Gu, G. H. Gao, Mingyu Wu, Ming-Yu Ge, Y. Huang, B. Y. Wu, Weiguang Cui, Qingcui Bu, J. J. Yang, He-Yang Liu, L. Chen, Xiaohua Liang, Yuan You, X. Y. Song, R. C. Ma, Shuo Xiao, D. K. Zhou, Youli Tuo, Yi Zhang, He Gao, Jin-Lu Qu, Shaolin Xiong, Xuchao Zhao, Bing Li, Ju Guan, R. J. Yang, F. Zhang, B. B. Yi, H. M. Zhang, Jing Jin, X. F. Li, Wenda Zhang, Bobing Wu, Ti-Pei Li, Li-Ming Song, C. Wang, Junqiang Zhang, Bai-Sheng Liu, C. K. Li, Fangjun Lu, Shuang-Nan Zhang, G. C. Xiao, W. C. Zhang, Jundan Nie, Hongwei Liu, HongSheng Zhao, S. N. Zhang, Q. Q. Yin, Y. P. Chen, Y. Nang, P. J. Wang, Shu-Mei Jia, Ge Ou, Yin Xu, Jia Huo, X. Y. Wen, Z. W. Li, and Xin Lu

Subjects
Physics, Accretion (meteorology), Magnetic moment, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, Astrophysics, Radius, 01 natural sciences, Magnetic field, Neutron star, Dipole, Pulsar, Space and Planetary Science, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Line (formation)
Abstract

GRO J1008-57, as a Be/X-ray transient pulsar, is considered to have the highest magnetic field in known neutron star X-ray binary systems. Observational data of the X-ray outbursts in GRO J1008-57 from 2017 to 2020 were collected by the Insight-HXMT satellite. In this work, the spin period of the neutron star in GRO J1008-57 was determined to be about 93.28 seconds in August 2017, 93.22 seconds in February 2018, 93.25 seconds in June 2019 and 93.14 seconds in June 2020. GRO J1008-57 evolved in the spin-up process with a mean rate of − ( 2.10 ± 0.05 ) × 10−4 s/d from 2009 – 2018, and turned into a spin down process with a rate of ( 6.7 ± 0.6 ) × 10−5 s/d from Feb 2018 to June 2019. During the type II outburst of 2020, GRO J1008-57 had the spin-up torque again. During the torque reversals, the pulse profiles and continuum X-ray spectra did not change significantly, and the cyclotron resonant scattering feature around 80 keV was only detected during the outbursts in 2017 and 2020. Based on the observed mean spin-up rate, we estimated the inner accretion disk radius in GRO J1008-57 (about 1 - 2 times of the Alfven radius) by comparing different accretion torque models of magnetic neutron stars. During the spin-down process, the magnetic torque should dominate over the matter accreting inflow torque, and we constrained the surface dipole magnetic field B ≥ 6 × 10 12 G for the neutron star in GRO J1008-57, which is consistent with the magnetic field strength obtained by cyclotron line centroid energy.

Published
2021

5. Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

Author

Alejandro Sáiz, Y. H. Yao, W. X. Wu, P. P. Zhang, Zhuo Li, R. Liu, Pak-Hin Thomas Tam, H. C. Li, Liang Chen, J. C. Wang, Y. L. Xin, L. Chen, M. J. Chen, Hong-Guang Wang, Y. J. Wei, S. Hu, Junjie Mao, Y. Q. Guo, J. Y. Liu, V. Rulev, P. F. Zhang, L. Xue, H. B. Hu, H. Liu, Rui Zhang, Linbin Yang, C. F. Feng, F. Ji, Xiaofei Zhang, F. Zheng, V. I. Stepanov, Ping Zhou, Q. H. Chen, H. R. Wu, Warit Mitthumsiri, X. C. Chang, Z. K. Zeng, C. D. Gao, Bin Zhou, W. L. Li, S. Z. Chen, M. M. Ge, Lei Zhao, Y. Z. Li, Y. Y. Guo, Y. J. Bi, Zhe Cao, Y. K. Hor, Xuejiao Li, H. D. Liu, S. H. Feng, B. Liu, Y. D. Cheng, Bo Zhang, H. K. Lv, H. M. Zhang, K. Levochkin, Y. J. Wang, L. X. Bai, Jixia Li, T. Montaruli, Duo Yan, Hefan Li, Ying Zhang, Bingshui Gao, Q. An, H. B. Xiao, J. R. Shi, X. D. Sheng, Z. X. Liu, W. H. Huang, M. L. Chen, Jianeng Zhou, Q. Gao, Minghao Qi, W. Zeng, Li-Sheng Geng, J. Chen, B. M. Chen, T. Wen, S. W. Cui, Z. X. Wang, Chiming Jin, S. B. Yang, L. Z. Zhao, C. W. Yang, J. B. Zhao, D.A. Kuleshov, Y. M. Xing, L. P. Wang, E. W. Liang, X. F. Wu, Zhe Li, B. Y. Pang, B. B. Li, X. Zuo, Cong Li, S. Q. Xi, Kun Fang, W. Gao, B. Z. Dai, Z. H. Wang, H. Cai, Jun Liu, Zhen Wang, J. C. He, Houdun Zeng, J. Fang, G. C. Xiao, Y. C. Nan, Z. G. Yao, Z. Y. Pei, Jun-Hui Fan, X. X. Zhou, Q. Yuan, H. B. Li, Shi-Qi Hu, G. G. Xin, J. F. Chang, Xufang Li, Oleg Shchegolev, G. M. Xiang, S. P. Zhao, W. Liu, X. L. Ji, M. J. Yang, H. H. He, R. Lu, Zhengguo Cao, Felix Aharonian, J. W. Zhang, H. C. Song, Yongchun Wang, Yugang Zhang, Wenwu Tian, He Zhang, Bai Yibing, S. L. He, Donglian Xu, Y. L. Feng, Zebo Tang, X. L. Guo, Y. D. Cui, X. J. Dong, Zheng Wang, Jun-Jie Wei, Q. B. Gou, Qizhi Huang, H. N. He, K. J. Zhu, M. Zha, B. D. Wang, Ruizhi Yang, X. N. Sun, Y. P. Wang, Z. C. Huang, H. L. Dai, H. Wang, Xiang Zhang, Xing-Yuan Hou, Yunchao Liu, H. Y. Jia, D. M. Wei, Z. G. Dai, Rong Xu, Fan Yang, A. Masood, F. Y. Li, Xinbo He, Youping Li, X. T. Huang, L. Y. Wang, X. R. Li, J. J. Xia, K. Jiang, Binyu Zhao, X. J. Hu, Yun-Feng Liang, W. Wang, Y. A. Han, J. G. Guo, Yu. V. Stenkin, Lang Shao, J.W. Xia, P. Pattarakijwanich, X. H. You, S.H. Chen, S. R. Zhang, C. Hou, Shuibin Lin, Lu Zhang, L. Feng, Xuelong Wang, S. Wu, X. X. Zhai, Xuliang Chen, C. X. Liu, L. L. Ma, Y. He, Z. X. Fan, Z. Y. You, F. R. Zhu, Y. W. Bao, Qie Sun, Yi Chen, X. G. Wang, Yi Zhang, Xiang-Yu Wang, D. H. Huang, R. Zhou, Hao Zhou, H. Zhu, X. J. Bi, D. della Volpe, Tao Zeng, T. L. Chen, Bin Ma, J. S. Wang, Cunguo Wang, L. X. Zhang, Shujuan Liu, N. Yin, N. Cheng, D. Bastieri, X. H. Cui, Cheng Li, W. J. Long, Shengxue Zhang, Axikegu, Li Zhang, G. H. Gong, Danzengluobu, M. H. Gu, Y. H. Yu, Jie Zhang, Y. Z. Fan, Dong Liu, C. Y. Wu, J. T. Cai, Long Chen, Y. Zheng, L. Q. Yin, Y. M. Ye, J. Y. Yang, B D Ettorre Piazzoli, David Ruffolo, Z. B. Sun, Cheng Guang Zhu, X. H. Ma, M. Heller, K. Li, Z. J. Jiang, J. Liu, Yong Zhang, Minghui Liu, R. N. Wang, and Jinyao Liu

Subjects
Physics, Multidisciplinary, Photon, COSMIC cancer database, Proton, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Electron, Astrophysics, 01 natural sciences, Galaxy, Supernova, Crab Nebula, Pulsar, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 1015 electronvolts) indicates the existence of the so-called PeVatrons—cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays1. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. 2). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane3–6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators. Observations of γ-rays with energies up to 1.4 PeV find that 12 sources in the Galaxy are PeVatrons, one of which is the Crab Nebula.

Published
2021

6. Physical origin of the non-physical spin evolution of MAXI J1820 + 070

Author

Cunguo Wang, Shaolin Xiong, B. S. Liu, B. B. Wu, H. Gao, J. Y. Liao, H. M. Zhang, R. C. Ma, Y. S. Wang, Y. F. Zhang, Xue-Feng Lu, C. Cai, Lian Tao, Shuinai Zhang, Tong Li, G. H. Gao, S. M. Jia, Tao Luo, M. Wu, X. Y. Song, Bo Li, Wenxiong Li, J. Jin, Xin-Fu Zhao, He-Yang Liu, S. Xiao, Lei Sun, Junqiang Zhang, J. L. Qu, Y. H. Tan, C. K. Li, Y. Nang, Peng Zhang, R. J. Yang, H. W. Liu, N. Sai, Yuan-Yuan Du, Y. G. Zheng, X. X. Li, Z. Chang, Y. B. Chen, Qiu-Yi Luo, Tian-Xiang Chen, Z. W. Li, F. J. Lu, Qingcui Bu, L. M. Song, S. J. Zheng, XiangYang Wen, X. H. Ma, Da-Wei Han, Ya Fang Huang, H. S. Zhao, Yuan You, Qi-Bin Yi, D. K. Zhou, P. J. Wang, W. S. Wang, Ge Ou, Yi Zhang, C. Z. Liu, Sisi Yang, J. Y. Nie, Xin Ren, Liang Zhang, Cheng-Cheng Guo, Ming-Yu Ge, L. Chen, Wan-Chang Zhang, Xiong Li, Yu-Dong Gu, X. J. Liu, Libin Wang, X. L. Cao, Q. Q. Yin, Y. P. Chen, Y. Wang, X. H. Liang, Fuqin Zhang, S. N. Zhang, Y. P. Xu, B. Y. Wu, Xuelong Li, J. Guan, L. D. Kong, Wei Cui, W. C. Zhang, Jia Huo, Gang Li, Wenhan Jiang, Bin Meng, Y. J. Yang, and G. C. Xiao

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Hardness ratio, Astrophysics::High Energy Astrophysical Phenomena, Spin transition, FOS: Physical sciences, Binary number, Astronomy and Astrophysics, Astrophysics, Black hole, Innermost stable circular orbit, Accretion disc, Space and Planetary Science, Coincident, Spectral analysis, 83C57, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract

We report on the Insight-HXMT observations of the new black hole X-ray binary MAXI J1820+070 during its 2018 outburst. Detailed spectral analysis via the continuum fitting method shows an evolution of the inferred spin during its high soft sate. Moreover, the hardness ratio, the non-thermal luminosity and the reflection fraction also undergo an evolution, exactly coincident to the period when the inferred spin transition takes place. The unphysical evolution of the spin is attributed to the evolution of the inner disc, which is caused by the collapse of a hot corona due to condensation mechanism or may be related to the deceleration of a jet-like corona. The studies of the inner disc radius and the relation between the disc luminosity and the inner disc radius suggest that, only at a particular epoch, did the inner edge of the disc reach the innermost stable circular orbit and the spin measurement is reliable. We then constrain the spin of MAXI J1820+070 to be a*=0.2^{+0.2}_{-0.3}. Such a slowly spinning black hole possessing a strong jet suggests that its jet activity is driven mainly by the accretion disc rather than by the black hole spin., Comment: 14 pages, 13 figures, 5 tables, accepted for publication in MNRAS

Published
2021

7. HXMT identification of a non-thermal X-ray burst from SGR J1935+2154 and with FRB 200428

Author

Y. J. Jin, Z. Chang, J. Y. Liao, H. M. Zhang, Y. F. Zhang, X. B. Li, Y. G. Li, Chun-sheng Zhang, Wenhan Jiang, Bo Li, Yu-Xuan Zhu, G. H. Gao, J. Jin, M. Wu, Y. Zhang, Xin-Fu Zhao, Zhi Zhang, Y. H. Tan, Y. X. Zhu, R. C. Shang, C. Cai, B. Lu, Fuqin Zhang, J. K. Deng, S. N. Zhang, W. C. Xue, X. X. Li, Y. G. Zheng, J. F. Zhou, Ming-Yu Ge, X. H. Ma, Wenxiong Li, Tian-Xiang Chen, F. J. Lu, Y. S. Wang, D. K. Zhou, Wei Cui, T. Zhang, Aimei Zhang, Lin Lin, Li-Ming Song, B. S. Liu, Lei Sun, C. Z. Liu, S. J. Zheng, Luhua Jiang, Y. P. Xu, B. B. Wu, X. L. Cao, Tao Luo, XiangYang Wen, Xue-Feng Lu, Bin Meng, S. Xiao, Y. B. Chen, Junqiang Zhang, Tong Li, H. W. Liu, N. Sai, Mao-Shun Li, Yunchao Liu, Sisi Yang, Y. J. Yang, S. M. Jia, Yuan You, L. D. Kong, Songbo Zhang, Cunguo Wang, Qi-Bin Yi, Yu-Dong Gu, Q. Q. Yin, Y. P. Chen, Xuelong Li, J. Guan, X. J. Liu, W. Z. Zhang, Yuan-Yuan Du, Gang Chen, X. H. Liang, G. C. Xiao, R. L. Zhuang, GuoQing Liu, Jia Huo, Y. Nang, Gang Li, Shaolin Xiong, Y. J. Zhang, H. Gao, Qiu-Yi Luo, Z. Zhang, Y. L. Tuo, J. W. Yang, Bing Zhang, B. Y. Wu, Lian Tao, X. Y. Song, H. S. Zhao, G. F. Wang, W. S. Wang, Ge Ou, W. C. Zhang, J. Y. Nie, Yi-Qiao Dong, Cheng-Cheng Guo, C. K. Li, H. Xu, Z. W. Li, Da-Wei Han, Z. L. Zhang, M. X. Fu, Yue Zhang, Ya Fang Huang, J. Z. Wang, L. Chen, Wan-Chang Zhang, Weiguang Cui, Qingcui Bu, Min Gao, and J. L. Qu

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010504 meteorology & atmospheric sciences, X-ray, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Magnetar, 01 natural sciences, Coincidence, Radio spectrum, 0103 physical sciences, Thermal, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Event (particle physics), 0105 earth and related environmental sciences, Delay time
Abstract

Fast radio bursts (FRBs) are short pulses observed in radio band from cosmological distances. One class of models invoke soft gamma-ray repeaters (SGRs), or magnetars, as the sources of FRBs. Some radio pulses have been observed from some magnetars, however, no FRB-like events had been detected in association any magnetar burst, including one giant flare. Recently, a pair of FRB-like bursts (FRB 200428 hereafter) separated by milliseconds (ms) were detected from the general direction of the Galactic magnetar SGR J1935+2154. Here we report the detection of a non-thermal X-ray burst in the 1-250 keV energy band with the Insight-HXMT satellite, which we identify as emitted from SGR J1935+2154. The burst showed two hard peaks with a separation of 34 ms, broadly consistent with that of the two bursts in FRB 200428. The delay time between the double radio and X-ray peaks is about 8.57 s, fully consistent with the dispersion delay of FRB 200428. We thus identify the non-thermal X-ray burst is associated with FRB 200428 whose high energy counterpart is the two hard peaks in X-ray. Our results suggest that the non-thermal X-ray burst and FRB 200428 share the same physical origin in an explosive event from SGR J1935+2154., 24 pages, 9 figures, 6 tables; initial submission to a journal on May 9th, 2020. Significant changes include updated localization and detailed spectral evolution of the X-ray burst, and better determination of the two narrow X-ray peaks corresponding to the two radio pulses. Conclusions are strengthened. Nature Astronomy online on Feb. 18, 2021

Published
2021

8. Joint analysis of energy and RMS spectra from MAXI J1535-571 with Insight-HXMT

Author

Z. W. Li, Jin-Lu Qu, He Gao, Y. C. Zhu, Xin Lu, J. X. Wang, ShaoZhen Liu, S. Yang, Xufang Li, Z. Zhang, Z. L. Zhang, Gang Li, W. C. Zhang, Yan Zhu, Long Ji, N. Sai, F. Zhang, Wenda Zhang, Bin Meng, Y. Tan, W. C. Jiang, Chuan-Peng Zhang, He-Yang Liu, Guo-Ming Chen, ShiJie Zheng, Bobing Wu, Y. G. Zheng, C. Cai, J. F. Zhou, D. K. Zhou, T. Luo, Ti-Pei Li, Shuo Xiao, Yuan-Yuan Du, Zhe Chang, Y. N. Liu, X.W. Ma, Tianran Chen, Shu-Mei Jia, Yu-Dong Gu, Bo Lu, Mingyu Wu, Lian Tao, Bing Li, Xuchao Zhao, Jing Jin, Jia Huo, X. Y. Wen, Ju Guan, Fangjun Lu, Jundan Nie, Ge Ou, X. F. Li, Cheng-Cheng Guo, M. Gao, Lei Sun, Hongwei Liu, Y. G. Li, C. Z. Liu, Luhua Jiang, H. M. Zhang, C. Wang, W. S. Wang, W. Z. Zhang, W. G. Li, He Xu, G. H. Gao, Jin-Yuan Liao, X. L. Cao, Min-Xue Fu, Shaolin Xiong, Y. Nang, Y. S. Wang, Junqiang Zhang, Mingzhe Li, Jinyi Yang, Y. Zhang, C. K. Li, Y. Huang, GuoQing Liu, P. J. Wang, Youcai Zhang, Jing-Kang Deng, Xiaohua Liang, G. F. Wang, Yi Zhang, Yuan You, Youli Tuo, Xin Ren, Yin Xu, Weiguang Cui, Q. Luo, Qingcui Bu, L. D. Kong, Y. B. Chen, Ming-Yu Ge, Xiao-Jing Liu, Da-Wei Han, Shuang-Nan Zhang, Li-Ming Song, Wei-Wei Cui, Aimei Zhang, Shuinai Zhang, Peng Zhang, Y. W. Dong, G. C. Xiao, HongSheng Zhao, Y. P. Chen, Xiaobo Li, L. Chen, Yi-Yan Yang, X. Y. Song, Y. J. Yang, T. Zhang, Q. B. Yi, and B. Y. Wu

Subjects
Physics, 010308 nuclear & particles physics, Oscillation, Astrophysics::High Energy Astrophysical Phenomena, Binary number, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Spectral line, law.invention, Telescope, Black hole, Space and Planetary Science, law, 0103 physical sciences, Modulation (music), Satellite, 010303 astronomy & astrophysics, Energy (signal processing)
Abstract

A new black hole X-ray binary (BHXRB) MAXI J1535-571 was discovered by MAXI during its outburst in 2017. Using observations taken by the first Chinese X-ray satellite, the Hard X-ray Modulation Telescope (dubbed as Insight-HXMT), we perform a joint spectral analysis (2-150 keV) in both energy and time domains. The energy spectra provide the essential input for probing the intrinsic Quasi-Periodic Oscillation (QPO) fractional rms spectra (FRS). Our results show that during the intermediate state, the energy spectra are in general consistent with those reported by Swift/XRT and NuSTAR. However, the QPO FRS become harder and the FRS residuals may suggest the presence of either an additional power-law component in the energy spectrum or a turn-over in the intrinsic QPO FRS at high energies.

Published
2020

9. Diagnostic of the spectral properties of Aquila X-1 by Insight-HXMT snapshots during the early propeller phase

Author

Jing-Kang Deng, Shaolin Xiong, Q. Luo, Xiaohua Liang, Yuan You, Youli Tuo, Jing Jin, Yin Xu, Jinyi Yang, X. F. Li, Z. L. Zhang, Ju Guan, Y. B. Chen, Lei Sun, Fangjun Lu, Da-Wei Han, Mingzhe Li, W. G. Li, Wenda Zhang, C. Cai, Chuan-Peng Zhang, Y. Huang, Z. W. Li, Jundan Nie, Can Güngör, Hongwei Liu, Li-Ming Song, Y. G. Li, Bobing Wu, Andrea Santangelo, Xufang Li, ShiJie Zheng, Min-Xue Fu, Luhua Jiang, Ti-Pei Li, Gang Li, Y. W. Dong, N. Sai, J. X. Wang, Y. Nang, G. C. Xiao, Shuinai Zhang, Jing Zhou, Xin Lu, Y. N. Liu, Yuan-Yuan Du, Jia Huo, X. Y. Wen, Junqiang Zhang, Y. Tan, F. Zhang, Bin Meng, W. C. Jiang, G. F. Wang, Yi Zhang, C. K. Li, Wei-Wei Cui, L. D. Kong, H. M. Zhang, Shuo Xiao, W. C. Zhang, M. Gao, Bo Lu, Guo-Ming Chen, Xuchao Zhao, C. Wang, Shu-Mei Jia, Shuang-Nan Zhang, G. H. Gao, Aimei Zhang, Ge Ou, Weiguang Cui, Qingcui Bu, HongSheng Zhao, C. Z. Liu, W. Z. Zhang, Y. Zhang, Mingyu Wu, Q. Q. Yin, Y. P. Chen, GuoQing Liu, Bing Li, Y. J. Yang, D. K. Zhou, Y. S. Wang, Yi Chen, Ming-Yu Ge, Xiao-Jing Liu, Xiaobo Li, Youcai Zhang, S. Yang, L. Chen, X. Y. Song, Zhe Chang, T. Zhang, X.W. Ma, Lian Tao, Yi-Nan Zhu, Cheng-Cheng Guo, W. S. Wang, T. Luo, Q. B. Yi, B. Y. Wu, Jin-Yuan Liao, X. L. Cao, He Gao, Z. Zhang, Yan Zhu, Long Ji, Tianran Chen, and Yu-Dong Gu

Subjects
Physics, Accretion (meteorology), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Spectral properties, Propeller, Phase (waves), Astronomy and Astrophysics, Astrophysics, 01 natural sciences, law.invention, Telescope, Accretion disc, Space and Planetary Science, Sky, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Spectral analysis, 010303 astronomy & astrophysics, media_common
Abstract

We study the 2018 outburst of Aql X-1 via the monitor of all sky X-ray image (MAXI) data. We show that the outburst starting in February 2018 is a member of short-low class in the frame of outburst duration and the peak count rate although the outburst morphology is slightly different from the other fast-rise-exponential-decay (FRED) type outbursts with a milder rising stage. We study the partial accretion in the weak propeller stage of Aql X-1 via the MAXI data of the 2018 outburst. We report on the spectral analysis of 3 observations of Aquila X-1 obtained by Insight – hard X-ray modulation telescope (Insight-HXMT) during the late decay stage of the 2018 outburst. We discuss that the data taken by Insight-HXMT is just after the transition to the weak propeller stage. Our analysis shows the necessity of a comptonization component to take into account the existence of an electron cloud resulting photons partly up-scattered.

Published
2020

10. Insight-HXMT study of the timing properties of Sco X-1

Author

J. Z. Wang, J. Y. Nie, Y. J. Yang, Xiaobo Li, Weiguang Cui, J. Guan, Qingcui Bu, L. M. Song, Yu-Dong Gu, G. C. Xiao, Luhua Jiang, J. Jin, D. K. Zhou, Y. X. Zhu, X. H. Liang, W. C. Zhang, B. Lu, GuoQing Liu, Ming-Yu Ge, Chun-sheng Zhang, Yi-Qiao Dong, Min Gao, B. B. Wu, Wenhan Jiang, Jia Huo, Y. H. Tan, Cheng-Cheng Guo, J. L. Qu, Gang Li, Y. B. Chen, F. J. Lu, Xin-Fu Zhao, R. C. Shang, J. F. Zhou, Bing Li, XiangYang Wen, Lian Tao, Y. S. Wang, Gang Chen, Wei Cui, B. Y. Wu, Tian-Xiang Chen, T. Zhang, X. Y. Song, X. J. Liu, Tao Luo, Da-Wei Han, Bin Meng, L. Chen, Mao-Shun Li, S. Xiao, Xue-Feng Lu, Tong Li, S. M. Jia, Fuqin Zhang, Z. Zhang, S. N. Zhang, Z. Chang, Yunchao Liu, R. L. Zhuang, Junqiang Zhang, Wan-Chang Zhang, W. S. Wang, Y. Nang, Ge Ou, Yuan-Yuan Du, W. Z. Zhang, Lei Sun, Y. J. Jin, C. Z. Liu, J. K. Deng, L. D. Kong, H. W. Liu, N. Sai, Shaolin Xiong, Cunguo Wang, Y. J. Zhang, X. H. Ma, H. Gao, Sisi Yang, Yupeng Xu, Qiu-Yi Luo, X. F. Li, H. S. Zhao, G. F. Wang, Y. L. Tuo, C. Cai, Wenxiong Li, J. W. Yang, Yu-Xuan Zhu, X. L. Cao, X. X. Li, S. J. Zheng, Yuan You, G. H. Gao, Qi-Bin Yi, M. Wu, Q. Q. Yin, Y. P. Chen, Y. Zhang, Y. G. Li, Aimei Zhang, J. Y. Liao, H. M. Zhang, Y. F. Zhang, Ya Fang Huang, Z. L. Zhang, C. K. Li, Z. W. Li, and M. X. Fu

Subjects
Physics, High energy, 010308 nuclear & particles physics, Phase (waves), Astronomy and Astrophysics, Astrophysics, Horizontal branch, 01 natural sciences, law.invention, Telescope, Root mean square, Space and Planetary Science, law, 0103 physical sciences, Modulation (music), 010303 astronomy & astrophysics, Energy (signal processing), Flare
Abstract

We present a detailed timing study of the brightest persistent X-ray source Sco X-1 using the data collected by the Hard X-ray Modulation Telescope ( I n s i g h t -HXMT) from July 2017 to August 2018. A complete Z-track hardness-intensity diagram (HID) is obtained. The normal branch oscillations (NBOs) at ∼ 6 Hz in the lower part of the normal branch (NB) and the flare branch oscillations (FBOs) at ∼ 16 Hz in the beginning part of the flaring branch (FB) are found in observations with the Low Energy X-ray Telescope (LE) and the Medium Energy X-ray Telescope (ME) of I n s i g h t -HXMT, while the horizontal branch oscillations (HBOs) at ∼ 40 Hz and the kilohertz quasi-periodic oscillations (kHz QPOs) at ∼ 800 Hz are found simultaneously above 20 keV for the first time on the horizontal branch (HB) by the High Energy X-ray Telescope (HE) and ME. We find that for all types of the observed QPOs, the centroid frequencies are independent of energy, while the root mean square (rms) increases with energy; the centroid frequencies of both the HBOs and kHz QPOs increase along the Z-track from the top to the bottom of the HB; and the NBOs show soft phase lags increasing with energy. A continuous QPO transition from the FB to NB in ∼ 200 s are also detected. Our results indicate that the non-thermal emission is the origin of all types of QPOs, the innermost region of the accretion disk is non-thermal in nature, and the corona is nonhomogeneous geometrically.

Published
2020

11. Peculiar disk behaviors of the black hole candidate MAXI J1348-630 in the hard state observed by Insight-HXMT and Swift

Author

W. Zhang, L. Tao, R. Soria, J. L. Qu, S. N. Zhang, S. S. Weng, L. Zhang, Y. N. Wang, Y. Huang, R. C. Ma, S. Zhang, M. Y. Ge, L. M. Song, X. Ma, Q. C. Bu, C. Cai, X. L. Cao, Z. Chang, L. Chen, T. X. Chen, Y. B. Chen, Y. Chen, Y. P. Chen, W. W. Cui, Y. Y. Du, G. H. Gao, H. Gao, Y. D. Gu, J. Guan, C. C. Guo, D. W. Han, J. Huo, S. M. Jia, W. C. Jiang, J. Jin, L. D. Kong, B. Li, C. K. Li, G. Li, T. P. Li, W. Li, X. Li, X. B. Li, X. F. Li, Z. W. Li, X. H. Liang, J. Y. Liao, B. S. Liu, C. Z. Liu, H. X. Liu, H. W. Liu, X. J. Liu, F. J. Lu, X. F. Lu, Q. Luo, T. Luo, B. Meng, Y. Nang, J. Y. Nie, G. Ou, X. Q. Ren, N. Sai, X. Y. Song, L. Sun, Y. Tan, Y. L. Tuo, C. Wang, L. J. Wang, P. J. Wang, W. S. Wang, Y. S. Wang, X. Y. Wen, B. Y. Wu, B. B. Wu, M. Wu, G. C. Xiao, S. Xiao, S. L. Xiong, R. J. Yang, S. Yang, Y. J. Yang, Y. R. Yang, Q. B. Yi, Q. Q. Yin, Y. Yuan, F. Zhang, H. M. Zhang, P. Zhang, W. C. Zhang, Y. F. Zhang, Y. H. Zhang, H. S. Zhao, X. F. Zhao, S. J. Zheng, Y. G. Zheng, and D. K. Zhou

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present a spectral study of the black hole candidate MAXI J1348-630 during its 2019 outburst, based on monitoring observations with Insight-HXMT and Swift. Throughout the outburst, the spectra are well fitted with power-law plus disk-blackbody components. In the soft-intermediate and soft states, we observed the canonical relation L ~ T_in^4 between disk luminosity L and peak colour temperature T_in, with a constant inner radius R_in (traditionally identified with the innermost stable circular orbit). At other stages of the outburst cycle, the behaviour is more unusual, inconsistent with the canonical outburst evolution of black hole transients. In particular, during the hard rise, the apparent inner radius is smaller than in the soft state (and increasing), and the peak colour temperature is higher (and decreasing). This anomalous behaviour is found even when we model the spectra with self-consistent Comptonization models, which take into account the up-scattering of photons from the disk component into the power-law component. To explain both those anomalous trends at the same time, we suggest that the hardening factor for the inner disk emission was larger than the canonical value of ~1.7 at the beginning of the outburst. A more physical trend of radii and temperature evolution requires a hardening factor evolving from ~3.5 at the beginning of the hard state to ~1.7 in the hard intermediate state. This could be evidence that the inner disk was in the process of condensing from the hot, optically thin medium and had not yet reached a sufficiently high optical depth for its emission spectrum to be described by the standard optically-thick disk solution., 20 pages, 10 figures, 4 tables, accepted by ApJ

Published
2022

12. Search for Gamma-Ray Bursts and Gravitational Wave Electromagnetic Counterparts with High Energy X-ray Telescope of \textit{Insight}-HXMT

Author

Yu-Dong Gu, C. K. Li, C. Cai, J. Y. Zhang, Wenxiong Li, Y. Nang, Z. Chang, Yuan-Yuan Du, Z. W. Li, B. Y. Wu, B. B. Wu, Wenhan Jiang, J. Y. Nie, Jia Huo, B. S. Liu, L. D. Kong, F. J. Lu, Y. B. Chen, X. Q. Ren, Yuyang Zhao, Fuqin Zhang, S. N. Zhang, X. X. Li, XiangYang Wen, Lian Tao, Peng Zhang, Gang Li, S. J. Zheng, Bo Li, D. K. Zhou, X. Y. Song, Y. G. Zheng, Y. S. Wang, Tian-Xiang Chen, X. J. Liu, Wei Zhang, Cunguo Wang, Cheng-Cheng Guo, Libin Wang, Yuan You, Qi-Bin Yi, W. C. Zhang, G. H. Gao, Lei Sun, Ya Fang Huang, Y. H. Tan, Wei Cui, M. Wu, Wei Chen, L. Chen, Yi-Yan Yang, Y. H. Zhang, Ming-Yu Ge, H. W. Liu, N. Sai, J. Y. Liao, X. H. Liang, H. M. Zhang, R. C. Ma, Y. P. Xu, Y. F. Zhang, X. B. Li, Xuelong Li, J. Guan, Qingcui Bu, X J Yang, L. M. Song, Tao Luo, S. Xiao, Da-Wei Han, J. L. Qu, Hongfei Liu, X. L. Cao, Q. Q. Yin, Y. P. Chen, J. Jin, Yu-Xuan Zhu, Xin-Fu Zhao, C. Z. Liu, Sisi Yang, R. J. Yang, Qiu-Yi Luo, Y. L. Tuo, Bin Meng, Z. Zhang, Shaolin Xiong, H. Gao, Y. J. Yang, G. C. Xiao, H. S. Zhao, P. J. Wang, W. S. Wang, Ge Ou, X. H. Ma, Xue-Feng Lu, Shuinai Zhang, Tong Li, and S. M. Jia

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, X-ray telescope, Astrophysics, Light curve, Coincidence, law.invention, Telescope, Space and Planetary Science, law, Sensitivity (control systems), Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract

The High Energy X-ray telescope (HE) on-board the Hard X-ray Modulation Telescope (\textit{Insight}-HXMT) can serve as a wide Field of View (FOV) gamma-ray monitor with high time resolution ($\mu$s) and large effective area (up to thousands cm$^2$). We developed a pipeline to search for Gamma-Ray Bursts (GRBs), using the traditional signal-to-noise ratio (SNR) method for blind search and the coherent search method for targeted search. By taking into account the location and spectrum of the burst and the detector response, the targeted coherent search is more powerful to unveil weak and sub-threshold bursts, especially those in temporal coincidence with Gravitational Wave (GW) events. Based on the original method in literature, we further improved the coherent search to filter out false triggers caused by spikes in light curves, which are commonly seen in gamma-ray instruments (e.g. \textit{Fermi}/GBM, \textit{POLAR}). We show that our improved targeted coherent search method could eliminate almost all false triggers caused by spikes. Based on the first two years of \textit{Insight}-HXMT/HE data, our targeted search recovered 40 GRBs, which were detected by either \textit{Swift}/BAT or \textit{Fermi}/GBM but too weak to be found in our blind search. With this coherent search pipeline, the GRB detection sensitivity of \textit{Insight}-HXMT/HE is increased to about 1.5E-08 erg/cm$^2$ (200 keV$-$3 MeV). We also used this targeted coherent method to search \textit{Insight}-HXMT/HE data for electromagnetic (EM) counterparts of LIGO-Virgo GW events (including O2 and O3a runs). However, we did not find any significant burst associated with GW events., Comment: 12 pages, 14 figures, 5 tables; accepted for publication in MNRAS

Published
2021

13. Broadband variability study of MAXI J1631-479 in its Hard-Intermediate State observed with Insight-HXMT

Author

B. B. Wu, J. Y. Liao, H. M. Zhang, R. C. Ma, Xue-Feng Lu, Tong Li, S. M. Jia, X. L. Cao, Y. F. Zhang, X. B. Li, Tian-Xiang Chen, C. Cai, Bin Meng, W. C. Zhang, Y. B. Chen, C. Z. Liu, X. H. Liang, Qiu-Yi Luo, Y. Nang, Ya Fang Huang, Wenxiong Li, L. Zhang, L. Sun, Y. J. Yang, Sisi Yang, Andrea Santangelo, G. C. Xiao, Y. P. Xu, Y. L. Tuo, D. K. Zhou, Cheng-Cheng Guo, G. H. Gao, X. J. Liu, M. Wu, C. K. Li, Bo Li, Qingcui Bu, T. M. Belloni, L. M. Song, Libin Wang, Peng Zhang, Tao Luo, S. Xiao, Fuqin Zhang, Y. H. Zhang, Shaolin Xiong, S. N. Zhang, Z. W. Li, X. B. Ma, H. Gao, Y. S. Wang, Q. Q. Yin, Y. P. Chen, Y. H. Tan, J. Jin, Xin-Fu Zhao, L. D. Kong, Lian Tao, G. Li, X. Y. Song, J. Y. Nie, Cunguo Wang, Da-Wei Han, X. X. Li, Xuelong Li, J. Guan, H. W. Liu, N. Sai, Wenhan Jiang, S. J. Zheng, J. L. Qu, Hongfei Liu, Z. Chang, Yuan You, Qi-Bin Yi, J. Y. Zhang, Jia Huo, Wei Cui, F. J. Lu, Yu-Dong Gu, XiangYang Wen, Ming-Yu Ge, H. S. Zhao, Z. S. Li, P. J. Wang, B. Y. Wu, W. Zhang, L. Chen, W. S. Wang, Ge Ou, and Yuan-Yuan Du

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Jet (fluid), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Plasma, Astrophysics, Photon energy, law.invention, Telescope, Acceleration, Space and Planetary Science, Modulation, law, Precession, Astrophysics - High Energy Astrophysical Phenomena, Noise (radio)
Abstract

We report the energy-resolved broadband timing analysis of the black hole X-ray transient MAXI J1631-479 during its 2019 outburst from February 11 to April 9, using data from the Insight-Hard X-ray Modulation Telescope (Insight-HXMT), which caught the source from its hard intermediate state to the soft state. Thanks to the large effective area of Insight-HXMT at high energies, we are able to present the energy dependence of fast variability up to ~100 keV. Type-C quasi-periodic oscillations (QPOs) with frequency varying between 4.9 Hz and 6.5 Hz are observed in the 1-100 keV energy band. While the QPO fractional rms increases with photon energy from 1 keV to ~10 keV and remains more or less constant from ~10 keV to ~100 keV, the rms of the flat-top noise first increases from 1 keV to ~8 keV then drops to less than 0.1% above ~30 keV. We suggest that the disappearance of the broadband variability above 30 keV could be caused by the non-thermal acceleration in the Comptonizing plasma. At the same time, the QPOs could be produced by the precession of either a small-scale jet or a hot inner flow model., To be published in The Astrophysical Journal

Published
2021

14. Discovery of a new $\gamma$-ray source LHAASO J0341+5258 with emission up to 200TeV

Author

Zhengguo Cao, L. Feng, Xufang Li, Zebo Tang, Jun-Jie Wei, C. Y. Wu, Jia Zhang, L. X. Bai, Yi Zhang, H. K. Lv, Jixia Li, L. L. Yang, Z. X. Wang, M. Zha, Y. M. Ye, X. H. Ma, L. P. Wang, X. G. Wang, Donglian Xu, X. L. Guo, Y. A. Han, Binyu Zhao, Yun-Feng Liang, Houdun Zeng, Zhe Li, Y. Su, B. Z. Dai, Z. G. Dai, Jinmei Liu, B. D'Ettorre Piazzoli, Z. G. Yao, Y. Zheng, W. X. Wu, M. L. Chen, Jianeng Zhou, Hefan Li, W. Wang, P. Pattarakijwanich, Rong Xu, J. J. Xia, X. X. Zhai, J. Fang, F. R. Zhu, Qie Sun, Yi Chen, H. B. Li, G. M. Xiang, W. Liu, B. Y. Pang, S. Wu, X. L. Ji, R. Lu, K. Li, Y. J. Bi, H. D. Liu, Y. D. Cheng, Bo Zhang, L. Q. Yin, Hanzhong Zhang, C. X. Liu, D. della Volpe, Y. D. Cui, Kun Fang, Yugang Zhang, E. W. Liang, Ping Zhou, Z. J. Jiang, Y. J. Wei, J. Liu, Yong Zhang, Duo Yan, Yu. V. Stenkin, S. L. He, Y. P. Wang, Z. X. Liu, D. H. Huang, R. N. Wang, S. M. Liu, F. Ji, V. Rulev, Y. Z. Li, H. H. He, H. Zhu, C. Hou, Zheng Wang, B. Q. Ma, Y. C. Nan, L. Xue, Jun Liu, Lu Zhang, H. Y. Jia, D. M. Wei, V. I. Stepanov, E. S. Chen, Sina Chen, K. J. Zhu, Y. Q. Qi, Fulai Guo, J. Y. Shi, Minghui Liu, Yi Liu, J. B. Zhao, H. Wang, X. F. Wu, Zhen Wang, Z. X. Fan, Z. Y. You, Shi-Qi Hu, J. Y. Yang, N. Cheng, Z. K. Zeng, C. D. Gao, X. H. You, Long Gao, H. C. Song, Lei Zhao, D.A. Kuleshov, X. X. Zhou, Q. Yuan, B. M. Chen, Ruizhi Yang, X. N. Sun, Shengxue Zhang, Danzengluobu, J. F. Chang, S. P. Zhao, H. Liu, J.W. Xia, W. Gao, G. C. Xiao, Felix Aharonian, Xinbo He, K. Jiang, Pak-Hin Thomas Tam, H. C. Li, Y. Wang, Y. Z. Fan, Dong Liu, Y. W. Bao, P. F. Zhang, X. J. Bi, H. N. He, T. L. Chen, L. Z. Zhao, X. J. Hu, R. Zhou, Ying Zhang, Oleg Shchegolev, Junjie Mao, Y. Q. Guo, F. Y. Li, K. Levochkin, J. T. Cai, X. D. Sheng, Cong Li, X. Zuo, B. B. Li, Long Chen, Yunchao Liu, H. L. Dai, T. Wen, S. W. Cui, S. Z. Chen, David Ruffolo, Y. M. Xing, H. R. Wu, Liang Chen, Xiang-Kun Dong, S. Hu, J. Y. Liu, X. Y. Huang, P. P. Zhang, X. H. Cui, Minghao Qi, Z. B. Sun, Y. Bai, Z. Y. Pei, Cheng Guang Zhu, Yuan-Hao Wang, Zhuo Li, Warit Mitthumsiri, H. M. Zhang, Q. An, Y. H. Yao, W. H. Huang, H. Zhou, W. J. Long, Binbin Zhou, Li-Sheng Geng, R. Liu, Xiang Zhang, J. G. Guo, J. W. Zhang, S. R. Zhang, Wenwu Tian, L. L. Ma, Q. Gao, C. F. Feng, Jiangang He, J. S. Wang, Cunguo Wang, Y. L. Xin, Z. C. Huang, H. B. Hu, N. Yin, B. Q. Qiao, Xin Li, Cheng Li, Jiajun Qin, M. H. Gu, Boyang Wang, Rui Zhang, H. B. Xiao, W. Zeng, L. X. Zhang, S. H. Feng, M. M. Ge, Axikegu, Yonggang Wang, M. J. Chen, Zhao-Qi Wang, Y. Y. Guo, Li Zhang, G. H. Gong, Zhe Cao, Y. K. Hor, Y. H. Yu, T. Montaruli, Jian Wang, Chiming Jin, Z. Min, Xuelong Wang, G. G. Xin, Kai-Kai Duan, D. Bastieri, Y. L. Feng, T. Ke, S. J. Lin, X. T. Huang, L. Y. Wang, B. Liu, Jingzhi Yan, Bingshui Gao, Xiang-Yu Wang, Yulong Li, Tao Zeng, Xuliang Chen, Y. He, C. W. Yang, Jun-Hui Fan, Q. B. Gou, W. L. Li, D. X. Xiao, Qizhi Huang, J. Chen, Xiao-Hu Zhang, H. Cai, M. J. Yang, S. Q. Xi, Hong-Guang Wang, Alejandro Sáiz, Q. H. Chen, S. B. Yang, Fan Yang, A. Masood, F. Zheng, Lang Shao, and M. Heller

Subjects
Physics, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Gamma ray, Flux, Astronomy and Astrophysics, Astrophysics, Galactic plane, Crab Nebula, Pulsar, Space and Planetary Science, Angular diameter, High Energy Physics::Experiment, Supernova remnant, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract

We report the discovery of a new unidentified extended $\gamma$-ray source in the Galactic plane named LHAASO J0341+5258 with a pre-trial significance of 8.2 standard deviations above 25 TeV. The best fit position is R.A.$=55.34^{\circ}\pm0.11^{\circ}$ and Dec$=52.97^{\circ}\pm0.07^{\circ}$. The angular size of LHAASO J0341+5258 is $0.29^\circ \pm 0.06^\circ_{stat} \pm0.02^\circ_{sys}$. The flux above 25 TeV is about $20\%$ of the flux of Crab Nebula. Although a power-law fit of the spectrum from 10 TeV to 200 TeV with the photon index $\alpha=2.98 \pm 0.19_{stat} \pm 0.02_{sys}$ is not excluded, the LHAASO data together with the flux upper limit at 10 GeV set by the Fermi LAT observation, indicate a noticeable steepening of an initially hard power-law spectrum %($\alpha \leq 1.75$) spectrum with a cutoff at $\approx 50$ TeV. We briefly discuss the origin of UHE gamma-rays. The lack of an energetic pulsar and a young SNR inside or in the vicinity of LHAASO J0341+5258 challenge, but do not exclude both the leptonic and hadronic scenarios of gamma-ray production., Comment: Accepted by APJL

Published
2021

15. Insight-HXMT observation on 4U 1608–52: Evolving spectral properties of a bright type-I X-ray burst

Author

S. N. Zhang, W. C. Jiang, W. S. Wang, Ge Ou, Z. Chang, J. F. Zhou, X.Q. Ren, C. Z. Liu, C. L. Zhang, Tian-Xiang Chen, Min Gao, H. S. Zhao, Sisi Yang, G. F. Wang, D. K. Zhou, Yi Zhang, X. J. Liu, J. L. Qu, G. C. Xiao, Jia Huo, Z. L. Zhang, Y. G. Li, M. X. Fu, Ya Fang Huang, Bing Li, F. Zhang, Chun-sheng Zhang, X. F. Li, Aimei Zhang, W. Z. Zhang, J. Z. Wang, Liang Sun, Y. B. Chen, Xue-Feng Lu, F. J. Lu, S. M. Jia, XiangYang Wen, Lian Tao, Yuan You, Junke Zhang, Gang Li, Y. S. Wang, Wei Zhang, B. Y. Wu, Qi-Bin Yi, B. B. Wu, Mao-Shun Li, Yunchao Liu, Y. J. Yang, Tao Luo, Xiaobo Li, L. D. Kong, S. Xiao, Yi-Qiao Dong, X. L. Cao, W. C. Zhang, Q. Luo, Weiguang Cui, X. X. Li, Yuan-Yuan Du, J. Y. Liao, H. M. Zhang, Gang Chen, Qingcui Bu, B. Lu, Y. H. Tan, J. K. Deng, Cheng-Cheng Guo, H. W. Liu, N. Sai, Q. Q. Yin, Y. P. Chen, Y. F. Zhang, C. K. Li, L. M. Song, Yu-Dong Gu, J. Jin, G. H. Gao, Xin-Fu Zhao, S. J. Zheng, Y. X. Zhu, C. Cai, Z. W. Li, Zhi-Xiang Zhang, X. H. Ma, Ming-Yu Ge, M. Wu, Y. Zhang, C. Wang, Wenxiong Li, Andrea Santangelo, Yu-Xuan Zhu, Shaolin Xiong, Luhua Jiang, Y. P. Xu, Y. J. Zhang, H. Gao, X. H. Liang, J. Guan, Ti-Pei Li, Y. L. Tuo, J. W. Yang, GuoQing Liu, Wei Cui, Long Ji, T. Zhang, L. Chen, J. Y. Nie, Da-Wei Han, Bin Meng, and Y. Nang

Subjects
Physics, Thermonuclear fusion, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Spectral properties, X-ray, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radius, Astrophysics, 01 natural sciences, symbols.namesake, Neutron star, Space and Planetary Science, 0103 physical sciences, Eddington luminosity, Reflection (physics), symbols, Spectral analysis, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The evidences for the influence of thermonuclear (type-I) X-ray bursts upon the surrounding environments in neutron star low-mass X-ray binaries (LMXB) were detected previously via spectral and timing analyses. Benefitting from a broad energy coverage of Insight-HXMT, we analyze one photospheric radius expansion (PRE) burst, and find an emission excess at soft X-rays. Our spectral analysis shows that, such an excess is not likely relevant to the disk reflection induced by the burst emission and can be attributed to an enhanced pre-burst/persistent emission. We find that the burst and enhanced persistent emissions sum up to exceed Eddington luminosity by ∼ 40 percentages. We speculate that the enhanced emission is from a region beyond the PRE radius, or through the Comptonization of the corona.

Published
2019

16. QPOs and Orbital elements of X-ray binary 4U 0115+63 during the 2017 outburst observed by Insight-HXMT

Author

Q Lou, Yuan You, Qi-Bin Yi, X. X. Li, S. J. Zheng, Cunguo Wang, J. Jin, H M Zhang, Xin-Fu Zhao, H. S. Zhao, Lei Sun, Wenhan Jiang, G. H. Gao, He-Yang Liu, Y. J. Yang, Xiong Li, Yu-Dong Gu, B. S. Liu, X. H. Ma, Y. P. Xu, Yi Zhang, Y. H. Tan, H. W. Liu, Y Z Ding, N. Sai, M. Wu, G. C. Xiao, W. C. Zhang, Yuan-Yuan Du, Y. G. Zheng, Y. Nang, C. Cai, L. Chen, C. Z. Liu, P. J. Wang, F. J. Lu, J. L. Qu, Bin Meng, Xue-Feng Lu, XiangYang Wen, L. D. Kong, Xuelong Li, J. Guan, S. M. Jia, Wenxiong Li, P Zhang, Fuqin Zhang, S. N. Zhang, Tian-Xiang Chen, Sisi Yang, X. L. Cao, C. K. Li, Y. B. Chen, D. K. Zhou, Y. S. Wang, Libin Wang, J. Y. Liao, Q. Q. Yin, Y. P. Chen, Lian Tao, Ti-Pei Li, R. C. Ma, Y. F. Zhang, Qingcui Bu, Bo Li, B. B. Wu, X. Y. Song, Shuang-Nan Zhang, Junqiang Zhang, W. S. Wang, L. M. Song, Wei Cui, Z. W. Li, Ming-Yu Ge, Wei Wang, Tao Luo, S. Xiao, Xin Ren, Ya Fang Huang, X. J. Liu, Jia Huo, C Zhi, Gang Li, B. Y. Wu, Shaolin Xiong, H. Gao, X. H. Liang, Y. L. Tuo, R. J. Yang, Wei Zhang, Cheng-Cheng Guo, Da-Wei Han, and J. Y. Nie

Subjects
Physics, Orbital elements, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, X-ray binary, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Light curve, 01 natural sciences, Spectral line, Luminosity, Neutron star, Wavelet, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Energy (signal processing)
Abstract

In this paper, we presented a detailed timing analysis of a prominent outburst of 4U 0115+63 detected by \textit{Insight}-HXMT in 2017 August. The spin period of the neutron star was determined to be $3.61398\pm 0.00002$ s at MJD 57978. We measured the period variability and extract the orbital elements of the binary system. The angle of periastron evolved with a rate of $0.048\pm0.003$ $yr^{-1}$. The light curves are folded to sketch the pulse profiles in different energy ranges. A multi-peak structure in 1-10 keV is clearly illustrated. We introduced wavelet analysis into our data analysis procedures to study QPO signals and perform a detailed wavelet analysis in many different energy ranges. Through the wavelet spectra, we report the discovery of a QPO at the frequency $\sim 10$ mHz. In addition, the X-ray light curves showed multiple QPOs in the period of $\sim 16-32 $ s and $\sim 67- 200 $ s. We found that the $\sim100$ s QPO was significant in most of the observations and energies. There exist positive relations between X-ray luminosity and their Q-factors and S-factors, while the QPO periods have no correlation with X-ray luminosity. In wavelet phase maps, we found that the pulse phase of $\sim 67- 200 $ s QPO drifting frequently while the $\sim 16-32 $ s QPO scarcely drifting. The dissipation of oscillations from high energy to low energy was also observed. These features of QPOs in 4U 0115+63 provide new challenge to our understanding of their physical origins., 14 pages, 9 figures, and 6 tables. This work has been submitted to MNRAS after the referee's report

Published
2021

17. A Variable Ionized Disk Wind in the Black Hole Candidate EXO 1846–031

Author

Junjie Mao, H. M. Zhang, Junqiang Zhang, ShiJie Zheng, C. K. Li, Thomas Dauser, Yuan-Yuan Du, C. Cai, R. C. Shang, Bing Li, Ming-Yu Ge, Xiao-Jing Liu, Y. J. Yang, Xufang Li, Gang Li, Shu-Mei Jia, Mariano Mendez, Ge Ou, Y. Nang, L. D. Kong, Yi Zhang, P. Maggi, N. Sai, Yin Xu, Long Ji, Yanan Wang, Bin Meng, Han Zhao, S. Yang, Q. B. Yi, B. Y. Wu, Lei Sun, Y. Huang, W. G. Li, Shaolin Xiong, Fangjun Lu, Li-Ming Song, C. Z. Liu, Jing Jin, Bobing Wu, Mingyu Wu, Xiaohua Liang, Javier A. García, X. F. Li, Yuan You, Y. S. Wang, Ti-Pei Li, Tianran Chen, Youli Tuo, Xiong Li, Yu-Dong Gu, Jin-Lu Qu, Y. Tan, W. C. Jiang, Zhe Chang, F. Zhang, X.W. Ma, Yuan Wang, Lian Tao, Diego Altamirano, L. Chen, X. Y. Song, D. K. Zhou, Wan-Chang Zhang, Jia Huo, X. Y. Wen, Z. W. Li, Xin Lu, G. C. Xiao, Jundan Nie, Hongwei Liu, Shuang-Nan Zhang, S. N. Zhang, Q. Q. Yin, Y. P. Chen, T. Luo, Liang Zhang, Wei Zhang, Cheng-Cheng Guo, W. S. Wang, Jin-Yuan Liao, X. L. Cao, G. H. Gao, Shuo Xiao, Xuchao Zhao, Ju Guan, Weiguang Cui, Qingcui Bu, Da-Wei Han, Q. Luo, Y. B. Chen, Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Astronomy

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010504 meteorology & atmospheric sciences, High-energy astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Accretion (astrophysics), Spectral line, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Ionization, 0103 physical sciences, Reflection (physics), Intermediate state, Emission spectrum, Spectral resolution, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, QC, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

After 34 years, the black-hole candidate EXO 1846-031 went into outburst again in 2019. We investigate its spectral properties in the hard intermediate and the soft states with NuSTAR and Insight-HXMT. A reflection component has been detected in the two spectral states but possibly originating from different illumination spectra: in the intermediate state, the illuminating source is attributed to a hard coronal component, which has been commonly observed in other X-ray binaries, whereas in the soft state the reflection is probably produced by the disk self-irradiation. Both cases support EXO 1846-031 as a low inclination system of ~40 degrees. An absorption line is clearly detected at ~7.2 keV in the hard intermediate state, corresponding to a highly ionized disk wind (log {\xi} > 6.1) with a velocity up to 0.06c. Meanwhile, quasi-simultaneous radio emissions have been detected before and after the X-rays, implying the co-existence of disk winds and jets in this system. Additionally, the observed wind in this source is potentially driven by magnetic forces. The absorption line disappeared in the soft state and a narrow emission line appeared at ~6.7 keV on top of the reflection component, which may be evidence for disk winds, but data with the higher spectral resolution are required to examine this., Comment: Accepted for publication in ApJ

Published
2021

18. Insight-HXMT observations of Swift J0243.6+6124: the evolution of RMS pulse fractions at super-Eddington luminosity

Author

Da-Wei Han, Luhua Jiang, Y. P. Xu, C. Cai, X. F. Li, Zhi Zhang, Mao-Shun Li, M. X. Fu, C. K. Li, Wenxiong Li, B. S. Liu, Wenhan Jiang, J. Z. Wang, X. H. Liang, Bing Li, Tao Luo, Y. B. Chen, B. Y. Wu, Weiguang Cui, S. Xiao, Qingcui Bu, Y. S. Wang, Z. W. Li, Chun-sheng Zhang, Yuan-Yuan Du, Xiaobo Li, X. L. Cao, J. Y. Nie, Y. X. Zhu, Ming-Yu Ge, Y. G. Zheng, Yi Jung Yang, J. Y. Liao, Min Gao, H. M. Zhang, Fuqin Zhang, S. N. Zhang, Y. Nang, Y. J. Jin, J. K. Deng, J. Guan, Wei Zhang, Z. Chang, Tian-Xiang Chen, Yi-Qiao Dong, Q. Q. Yin, Y. P. Chen, Cheng-Cheng Guo, Yunchao Liu, J. L. Qu, F. J. Lu, Long Ji, X. H. Ma, GuoQing Liu, Yan Ji Yang, Jia Huo, Gang Chen, W. C. Zhang, Y. F. Zhang, B. Lu, XiangYang Wen, B. B. Wu, Junqiang Zhang, Li-Ming Song, G Ou, Z. L. Zhang, Gang Li, Lian Tao, Y. H. Tan, D. K. Zhou, Xue-Feng Lu, Zhao Zhang, X. Y. Song, Ya Fang Huang, Tong Li, Lei Sun, L. Chen, Yuan You, J. F. Zhou, S. M. Jia, Yu-Xuan Zhu, Ling-Jun Wang, W. Z. Zhang, Qi-Bin Yi, Cunguo Wang, Wei Cui, T. Zhang, L. D. Kong, X. J. Liu, H. W. Liu, X. X. Li, Yu-Dong Gu, N. Sai, S. J. Zheng, Y. G. Li, Aimei Zhang, G. H. Gao, M. Wu, Y. Zhang, R. L. Zhuang, J. Jin, Xin-Fu Zhao, R. C. Shang, C. Z. Liu, Sisi Yang, Shaolin Xiong, Y. J. Zhang, H. Gao, Y. L. Tuo, J. W. Yang, Qiu-Yi Luo, G. C. Xiao, H. S. Zhao, Bin Meng, P. J. Wang, G. F. Wang, and W. S. Wang

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Swift, Physics, Astrophysics::High Energy Astrophysical Phenomena, Phase (waves), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Relative strength, Astrophysics::Cosmology and Extragalactic Astrophysics, Pulse (physics), Luminosity, symbols.namesake, Radiation pressure, Space and Planetary Science, Eddington luminosity, symbols, Astrophysics::Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, computer, Energy (signal processing), Astrophysics::Galaxy Astrophysics, computer.programming_language
Abstract

Based on Insight-HXMT data, we report on the pulse fraction evolution during the 2017–2018 outburst of the newly discovered first Galactic ultraluminous X-ray (ULX) source Swift J0243.6+6124. The pulse fractions of 19 observation pairs selected in the rising and fading phases with similar luminosity are investigated. The results show a general trend of the pulse fraction increasing with luminosity and energy at supercritical luminosity. However, the relative strength of the pulsation between each pair evolves strongly with luminosity. The pulse fraction in the rising phase is larger at luminosity below 7.71 × 1038 erg s−1, but smaller at above. A transition luminosity is found to be energy independent. Such a phenomenon is first confirmed by Insight-HXMT observations and we speculate that it may have relation with the radiation-pressure-dominated accretion disc.

Published
2020

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

Author

Yanan Wang, Long Ji, S. N. Zhang, Mariano Méndez, J. L. Qu, Pierre Maggi, M. Y. Ge, Erlin Qiao, L. Tao, S. Zhang, Diego Altamirano, L. Zhang, X. Ma, F. J. Lu, T. P. Li, Y. Huang, S. J. Zheng, Y. P. Chen, Z. Chang, Y. L. Tuo, C. Güngör, L. M. Song, Y. P. Xu, X. L. Cao, Y. Chen, C. Z. Liu, Q. C. Bu, C. Cai, G. Chen, L. Chen, T. X. Chen, Y. B. Chen, W. Cui, W. W. Cui, J. K. Deng, Y. W. Dong, Y. Y. Du, M. X. Fu, G. H. Gao, H. Gao, M. Gao, Y. D. Gu, J. Guan, C. C. Guo, D. W. Han, J. Huo, S. M. Jia, L. H. Jiang, W. C. Jiang, J. Jin, Y. J. Jin, L. D. Kong, B. Li, C. K. Li, G. Li, M. S. Li, W. Li, X. Li, X. B. Li, X. F. Li, Y. G. Li, Z. W. Li, X. H. Liang, J. Y. Liao, G. Q. Liu, H. W. Liu, X. J. Liu, Y. N. Liu, B. Lu, X. F. Lu, Q. Luo, T. Luo, B. Meng, Y. Nang, J. Y. Nie, G. Ou, N. Sai, R. C. Shang, X. Y. Song, L. Sun, Y. Tan, G. F. Wang, J. Wang, W. S. Wang, Y. D. Wang, Y. S. Wang, X. Y. Wen, B. B. Wu, B. Y. Wu, M. Wu, G. C. Xiao, S. Xiao, S. L. Xiong, J. W. Yang, S. Yang, Y. J. Yang, Q. B. Yi, Q. Q. Yin, Y. You, A. M. Zhang, C. M. Zhang, F. Zhang, H. M. Zhang, J. Zhang, T. Zhang, W. C. Zhang, W. Zhang, W. Z. Zhang, Y. Zhang, Y. F. Zhang, Y. J. Zhang, Z. Zhang, Z. L. Zhang, H. S. Zhao, X. F. Zhao, D. K. Zhou, J. F. Zhou, R. L. Zhuang, Y. X. Zhu, Y. Zhu, Lingjun Wang, Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Astronomy

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Range (particle radiation), Jet (fluid), Photon, 010504 meteorology & atmospheric sciences, Hardness ratio, Black holes, Astrophysics::High Energy Astrophysical Phenomena, Time lag, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Low-mass x-ray binary stars, Space and Planetary Science, 0103 physical sciences, Broadband, Transient (oscillation), Electronic band structure, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Compact objects, 0105 earth and related environmental sciences
Abstract

We study the evolution of the temporal properties of MAXI 1820+070 during the 2018 outburst in its hard state from MJD 58190 to 58289 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 58257, suggesting a transition occurred at 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; first increase until around MJD 58257 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., Comment: Accepted for publication in ApJ

Published
2020

20. Switches between accretion structures during flares in 4U 1901+03

Author

Z. Chang, Fuqin Zhang, S. N. Zhang, Qiu-Yi Luo, Y. B. Chen, B. B. Wu, Tao Luo, Aimei Zhang, J. Y. Zhang, Ming-Yu Ge, Armin Nabizadeh, Y. G. Li, S. Xiao, Y. L. Tuo, J. W. Yang, L. Chen, Chun-sheng Zhang, Peng Zhang, Yu-Dong Gu, Sergey S. Tsygankov, C. K. Li, Y. J. Jin, J. Y. Nie, M. X. Fu, Yue Zhang, X. J. Liu, Luhua Jiang, Y. P. Xu, Zhao Zhang, G. C. Xiao, Bo Li, H. Xu, Yu-Xuan Zhu, J. Z. Wang, X. H. Liang, W. Z. Zhang, L. Sun, Z. W. Li, G. H. Gao, Yanji Yang, Wan-Chang Zhang, Weiguang Cui, C. Cai, F. J. Lu, Yunchao Liu, Qingcui Bu, X. L. Cao, B. S. Liu, Bin Meng, D. K. Zhou, Y. J. Yang, Shaolin Xiong, Wenxiong Li, Tian-Xiang Chen, Lian Tao, Yi Zhang, Y. J. Zhang, M. Wu, Andrea Santangelo, XiangYang Wen, Suleimanov, H. Gao, Z. Zhang, L. D. Kong, X. Y. Song, Long Ji, W. C. Zhang, Q. B. Yi, B. Y. Wu, Mao-Shun Li, Q. Q. Yin, You-Hong Zhang, H. W. Liu, N. Sai, Da-Wei Han, J. Y. Liao, H. M. Zhang, Zhi Zhang, Ya Fang Huang, Y. F. Zhang, Min Gao, X. B. Li, B. Lu, J. L. Qu, Yi-Qiao Dong, Wenhan Jiang, Cheng-Cheng Guo, Y. S. Wang, Doroshenko, Yuan-Yuan Du, C. Z. Liu, Y X Zhu, Y. P. Chen, Sisi Yang, Y. H. Tan, J. F. Zhou, J. Jin, Xin-Fu Zhao, R. C. Shang, Xuelong Li, J. Guan, GuoQing Liu, Jia Huo, Gang Li, Lorenzo Ducci, Wei Cui, T. Zhang, Li-Ming Song, Xue-Feng Lu, Shuinai Zhang, S. M. Jia, He-Yang Liu, Y. Nang, R. L. Zhuang, J. K. Deng, C. Wang, X. H. Ma, H. S. Zhao, Ti-Pei Li, P. J. Wang, G. F. Wang, W. S. Wang, Ge Ou, Gang Chen, Yuan You, X. X. Li, and S. J. Zheng

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Accretion (astrophysics), Spectral line, Beam pattern, Neutron star, Accretion rate, Pulsar, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Polar cap, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We report on our analysis of the 2019 outburst of the X-ray accreting pulsar 4U 1901+03 observed with Insight-HXMT and NICER. Both spectra and pulse profiles evolve significantly in the decaying phase of the outburst. Dozens of flares are observed throughout the outburst. They are more frequent and brighter at the outburst peak. We find that the flares, which have a duration from tens to hundreds of seconds, are generally brighter than the persistent emission by a factor of $\sim$ 1.5. The pulse profile shape during the flares can be significantly different than that of the persistent emission. In particular, a phase shift is clearly observed in many cases. We interpret these findings as direct evidence of changes of the pulsed beam pattern, due to transitions between the sub- and super-critical accretion regimes on a short time scale. We also observe that at comparable luminosities the flares' pulse profiles are rather similar to those of the persistent emission. This indicates that the accretion on the polar cap of the neutron star is mainly determined by the luminosity, i.e., the mass accretion rate., 11 pages, 8 figures, accepted for publication in MNRAS

Published
2020

21. A search for prompt gamma-ray counterparts to fast radio bursts in the Insight-HXMT data

Author

C. Guidorzi, M. Marongiu, R. Martone, L. Nicastro, S. L. Xiong, J. Y. Liao, G. Li, S. N. Zhang, L. Amati, F. Frontera, M. Orlandini, P. Rosati, E. Virgilli, S. Zhang, Q. C. Bu, C. Cai, X. L. Cao, Z. Chang, G. Chen, L. Chen, T. X. Chen, Y. B. Chen, Y. P. Chen, W. Cui, W. W. Cui, J. K. Deng, Y. W. Dong, Y. Y. Du, M. X. Fu, G. H. Gao, H. Gao, M. Gao, M. Y. Ge, Y. D. Gu, J. Guan, C. C. Guo, D. W. Han, Y. Huang, J. Huo, S. M. Jia, L. H. Jiang, W. C. Jiang, J. Jin, Y. J. Jin, L. D. Kong, B. Li, C. K. Li, M. S. Li, T. P. Li, W. Li, X. Li, X. B. Li, X. F. Li, Y. G. Li, Z. W. Li, X. H. Liang, B. S. Liu, C. Z. Liu, G. Q. Liu, H. W. Liu, X. J. Liu, Y. N. Liu, B. Lu, F. J. Lu, X. F. Lu, Q. Luo, T. Luo, R. C. Ma, X. Ma, B. Meng, Y. Nang, J. Y. Nie, G. Ou, J. L. Qu, N. Sai, R. C. Shang, L. M. Song, X. Y. Song, L. Sun, Y. Tan, L. Tao, Y. L. Tuo, C. Wang, G. F. Wang, J. Wang, W. S. Wang, Y. S. Wang, X. Y. Wen, B. Y. Wu, B. B. Wu, M. Wu, G. C. Xiao, S. Xiao, Y. P. Xu, J. W. Yang, S. Yang, Y. J. Yang, Q. B. Yi, Q. Q. Yin, Y. You, A. M. Zhang, C. M. Zhang, F. Zhang, H. M. Zhang, J. Zhang, T. Zhang, W. C. Zhang, W. Zhang, W. Z. Zhang, Y. Zhang, Y. F. Zhang, Y. J. Zhang, Z. Zhang, Z. L. Zhang, H. S. Zhang, X. F. Zhang, S. J. Zheng, D. K. Zhou, J. F. Zhou, Y. X. Zhu, Y. Zhu, and R. L. Zhuang

Subjects
radiation mechanism: non-thermal, Astrophysics::High Energy Astrophysical Phenomena, Continuum (design consultancy), Socio-culturale, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Magnetar, 01 natural sciences, Luminosity, law.invention, Telescope, fast radio burst, radiation mechanism: non-thermal, law, 0103 physical sciences, fast radio burst, 010306 general physics, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Gamma ray, Astronomy and Astrophysics, Stars, Neutron star, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena
Abstract

No robust detection of prompt electromagnetic counterparts to fast radio bursts (FRBs) has yet been obtained, in spite of several multi-wavelength searches carried out so far. Specifically, X/gamma-ray counterparts are predicted by some models. We planned on searching for prompt gamma-ray counterparts in the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) data, taking advantage of the unique combination of large effective area in the keV-MeV energy range and of sub-ms time resolution. We selected 39 FRBs that were promptly visible from the High-Energy (HE) instrument aboard Insight-HXMT. After calculating the expected arrival times at the location of the spacecraft, we searched for a significant excess in both individual and cumulative time profiles over a wide range of time resolutions, from several seconds down to sub-ms scales. Using the dispersion measures in excess of the Galactic terms, we estimated the upper limits on the redshifts. No convincing signal was found and for each FRB we constrained the gamma-ray isotropic-equivalent luminosity and the released energy as a function of emission timescale. For the nearest FRB source, the periodic repeater FRB180916.J0158+65, we find $L_{\gamma,iso}, Comment: 15 pages, 3 figures, 6 tables, accepted by A&A

Published
2020
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22. Insight-HXMT firm detection of the highest energy fundamental cyclotron resonance scattering feature in the spectrum of GRO J1008-57

Author

M. Y. Ge, L. Ji, S. N. Zhang, A. Santangelo, C. Z. Liu, V. Doroshenko, R. Staubert, J. L. Qu, S. Zhang, F. J. Lu, L. M. Song, T. P. Li, L. Tao, Y. P. Xu, X. L. Cao, Y. Chen, Q. C. Bu, C. Cai, Z. Chang, G. Chen, L. Chen, T. X. Chen, Y. B. Chen, Y. P. Chen, W. Cui, W. W. Cui, J. K. Deng, Y. W. Dong, Y. Y. Du, M. X. Fu, G. H. Gao, H. Gao, M. Gao, Y. D. Gu, J. Guan, C. C. Guo, D. W. Han, Y. Huang, J. Huo, S. M. Jia, L. H. Jiang, W. C. Jiang, J. Jin, Y. J. Jin, L. D. Kong, B. Li, C. K. Li, G. Li, M. S. Li, W. Li, X. Li, X. B. Li, X. F. Li, Y. G. Li, Z. W. Li, X. H. Liang, J. Y. Liao, B. S. Liu, G. Q. Liu, H. W. Liu, X. J. Liu, Y. N. Liu, B. Lu, X. F. Lu, Q. Luo, T. Luo, X. Ma, B. Meng, Y. Nang, J. Y. Nie, G. Ou, N. Sai, R. C. Shang, X. Y. Song, L. Sun, Y. Tan, Y. L. Tuo, C. Wang, G. F. Wang, J. Wang, L. J. Wang, W. S. Wang, Y. D. Wang, Y. S. Wang, X. Y. Wen, B. B. Wu, B. Y. Wu, M. Wu, G. C. Xiao, S. Xiao, S. L. Xiong, H. Xu, J. W. Yang, S. Yang, Y. J. Yang, Q. B. Yi, Q. Q. Yin, Y. You, A. M. Zhang, C. M. Zhang, F. Zhang, H. M. Zhang, J. Zhang, T. Zhang, W. C. Zhang, W. Zhang, W. Z. Zhang, Y. Zhang, Y. F. Zhang, Y. J. Zhang, Z. Zhang, Z. L. Zhang, H. S. Zhao, X. F. Zhao, S. J. Zheng, Y. G. Zheng, D. K. Zhou, J. F. Zhou, R. L. Zhuang, Y. X. Zhu, and Y. Zhu

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010504 meteorology & atmospheric sciences, Scattering, Astrophysics::High Energy Astrophysical Phenomena, Cyclotron resonance, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Inelastic scattering, 01 natural sciences, Resonance (particle physics), Spectral line, Pulsar, Space and Planetary Science, 0103 physical sciences, Continuum (set theory), Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Line (formation)
Abstract

We report on the observation of the accreting pulsar GRO J1008-57 performed by Insight-HXMT at the peak of the source's 2017 outburst. Pulsations are detected with a spin period of 93.283(1) s. The pulse profile shows double peaks at soft X-rays, and only one peak above 20 keV. The spectrum is well described by the phenomenological models of X-ray pulsars. A cyclotron resonant scattering feature is detected with very high statistical significance at a centroid energy of $E_{\rm cyc}=90.32_{-0.28}^{+0.32}$ keV, for the reference continuum and line models, HIGHECUT and GABS respectively. Detection is very robust with respect to different continuum models. The line energy is significantly higher than what suggested from previous observations, which provided very marginal evidence for the line. This establishes a new record for the centroid energy of a fundamental cyclotron resonant scattering feature observed in accreting pulsars. We also discuss the accretion regime of the source during the Insight-HXMT observation., Comment: 8 pages, 3 figures, accepted for publication in ApJL

Published
2020
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23. Constraining the transient high-energy activity of FRB180916.J0158+65 with Insight-HXMT followup observations

Author

L. Chen, Yu-Dong Gu, Ya Fang Huang, R. J. Yang, Y. J. Yang, L. Wang, Junqiang Zhang, Wenhan Jiang, Qiu-Yi Luo, X. H. Liang, C. Z. Liu, G. C. Xiao, B. Y. Wu, Y. L. Tuo, Sisi Yang, He-Yang Liu, Wei Cui, W. S. Wang, Xiaobo Li, Wei Zhang, G. H. Gao, Ge Ou, Bing Li, B. B. Wu, Bin Meng, C. Guidorzi, F. Frontera, Yi Zhang, C. Cai, Luciano Nicastro, Lei Sun, Mauro Orlandini, M. Wu, J. Jin, Xin-Fu Zhao, H. S. Zhao, Y. Nang, Cheng-Cheng Guo, Y. P. Xu, Tao Luo, Yuan You, Qingcui Bu, S. Xiao, C. K. Li, Qi-Bin Yi, Shaolin Xiong, P. J. Wang, Wenxiong Li, Y. B. Chen, J. Y. Liao, H. M. Zhang, L. D. Kong, B. S. Liu, X. X. Li, H. Gao, H. W. Liu, N. Sai, Z. W. Li, W. C. Zhang, R. C. Ma, Min Gao, Fuqin Zhang, Y. F. Zhang, S. N. Zhang, D. K. Zhou, C. Wang, J. L. Qu, J. Guan, Lorenzo Amati, Y. G. Zheng, Y. S. Wang, Xin Ren, Tian-Xiang Chen, E. Virgilli, Lian Tao, Z. Chang, Da-Wei Han, Jia Huo, Y. H. Tan, X. Y. Song, X. F. Li, Gang Li, P. Zhang, Ming-Yu Ge, J. Y. Nie, Yuan-Yuan Du, F. J. Lu, XiangYang Wen, X. H. Ma, Li-Ming Song, Xue-Feng Lu, Tong Li, S. M. Jia, X. J. Liu, X. L. Cao, Q. Q. Yin, Y. P. Chen, S. J. Zheng, ITA, and CHN

Subjects
Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Socio-culturale, Context (language use), Astrophysics, Magnetar, 01 natural sciences, law.invention, Telescope, stars: magnetars, law, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Fast radio burst, Detector, Astronomy and Astrophysics, radiation mechanisms: non-thermal, stars: magnetars, radiation mechanisms: non-thermal, Wavelength, Space and Planetary Science, Phase space, Astrophysics - High Energy Astrophysical Phenomena, Energy (signal processing)
Abstract

A link between magnetars and fast radio burst (FRB) sources has finally been established. In this context, one of the open issues is whether/which sources of extra galactic FRBs exhibit X/gamma-ray outbursts and whether it is correlated with radio activity. We aim to constrain possible X/gamma-ray burst activity from one of the nearest extragalactic FRB sources currently known over a broad energy range, by looking for bursts over a range of timescales and energies that are compatible with being powerful flares from extragalactic magnetars. We followed up the as-yet nearest extragalactic FRB source at a mere 149 Mpc distance, the periodic repeater FRB180916.J0158+65, during the active phase on February 4-7, 2020, with the Insight-Hard X-ray Modulation Telescope (HXMT). Taking advantage of the combination of broad band, large effective area, and several independent detectors available, we searched for bursts over a set of timescales from 1 ms to 1.024 s with a sensitive algorithm, that had previously been characterised and optimised. Moreover, through simulations we studied the sensitivity of our technique in the released energy-duration phase space for a set of synthetic flares and assuming different energy spectra. We constrain the possible occurrence of flares in the 1-100 keV energy band to E, 10 pages, 3 figures, accepted by A&A

Published
2020

24. X-ray reprocessing in accreting pulsar GX 301-2 observed with Insight-HXMT

Author

G. H. Gao, X. X. Li, M. Wu, S. J. Zheng, Y. G. Zheng, Y. Nang, Mauro Orlandini, J. Y. Liao, H. M. Zhang, Y. L. Tuo, Y. J. Yang, R. C. Ma, Y. F. Zhang, X. B. Li, B. S. Liu, Yuan You, X. Q. Ren, Yanji Yang, Armin Nabizadeh, C. Cai, L. Chen, Tian-Xiang Chen, Wenxiong Li, Wan-Chang Zhang, W. S. Wang, Yi Zhang, Ge Ou, Andrea Santangelo, R. J. Yang, Bo Li, Peng Zhang, Qiu-Yi Luo, B. B. Wu, Cunguo Wang, H. S. Zhao, Li-Ming Song, Ming-Yu Ge, C. K. Li, F. J. Lu, Xue-Feng Lu, Y. P. Chen, Shuinai Zhang, Tong Li, Y. H. Tan, P. J. Wang, J. Y. Zhang, Victor Doroshenko, Shaolin Xiong, S. M. Jia, XiangYang Wen, Ling-Jun Wang, H. Gao, Jiren Liu, X. H. Ma, Z. W. Li, Yuan-Yuan Du, C. Z. Liu, D. K. Zhou, Sisi Yang, Ya Fang Huang, J. Jin, Xin-Fu Zhao, G. Li, Tao Luo, S. Xiao, Yu-Dong Gu, X. J. Liu, D. Gavran, X. L. Cao, Q. Q. Yin, Q. B. Yi, B. Y. Wu, V. F. Suleimanov, L. D. Kong, Y. B. Chen, X. H. Liang, L. Sun, Fuqin Zhang, S. N. Zhang, Long Ji, Z. Chang, Y. H. Zhang, Y. P. Xu, Wenhan Jiang, H. W. Liu, N. Sai, Y. S. Wang, W. C. Zhang, Xuelong Li, J. Guan, Lian Tao, Cheng-Cheng Guo, X. Y. Song, Jia Huo, Lorenzo Ducci, J. Y. Nie, Bin Meng, Wei Cui, G. C. Xiao, Qingcui Bu, Da-Wei Han, J. L. Qu, Hongfei Liu, ITA, DEU, and CHN

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Accretion (meteorology), Astrophysics::High Energy Astrophysical Phenomena, X-ray, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radiation, 01 natural sciences, Neutron star, Pulsar, Space and Planetary Science, Ionization, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010306 general physics, Absorption (electromagnetic radiation), Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Equivalent width, Astrophysics::Galaxy Astrophysics
Abstract

We investigate the absorption and emission features in observations of GX 301-2 detected with Insight-HXMT/LE in 2017-2019. At different orbital phases, we found prominent Fe Kalpha, Kbeta and Ni Kalpha lines, as well as Compton shoulders and Fe K-shell absorption edges. These features are due to the X-ray reprocessing caused by the interaction between the radiation from the source and surrounding accretion material. According to the ratio of iron lines Kalpha and Kbeta, we infer the accretion material is in a low ionisation state. We find an orbital-dependent local absorption column density, which has a large value and strong variability around the periastron. We explain its variability as a result of inhomogeneities of the accretion environment and/or instabilities of accretion processes. In addition, the variable local column density is correlated with the equivalent width of the iron Kalpha lines throughout the orbit, which suggests that the accretion material near the neutron star is spherically distributed., Comment: 10 pages, 5 figures, 2 tables, accepted for publication in MNRAS

Published
2020
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25. Discovery of delayed spin-up behavior following two large glitches in the Crab pulsar, and the statistics of such processes

Author

M. Y. Ge, S. N. Zhang, F. J. Lu, T. P. Li, J. P. Yuan, X. P. Zheng, Y. Huang, S. J. Zheng, Y. P. Chen, Z. Chang, Y. L. Tuo, Q. Cheng, C. Güngör, L. M. Song, Y. P. Xu, X. L. Cao, Y. Chen, C. Z. Liu, S. Zhang, J. L. Qu, Q. C. Bu, C. Cai, G. Chen, L. Chen, M. Z. Chen, T. X. Chen, Y. B. Chen, W. Cui, W. W. Cui, J. K. Deng, Y. W. Dong, Y. Y. Du, M. X. Fu, G. H. Gao, H. Gao, M. Gao, Y. D. Gu, J. Guan, C. C. Guo, D. W. Han, L. F. Hao, J. Huo, S. M. Jia, L. H. Jiang, W. C. Jiang, C. J. Jin, J. Jin, Y. J. Jin, L. D. Kong, B. Li, D. Li, C. K. Li, G. Li, M. S. Li, W. Li, X. Li, X. B. Li, X. F. Li, Y. G. Li, Z. W. Li, Z. X. Li, Z. Y. Liu, X. H. Liang, J. Y. Liao, G. Q. Liu, H. W. Liu, X. J. Liu, Y. N. Liu, B. Lu, X. F. Lu, Q. Luo, T. Luo, X. Ma, B. Meng, Y. Nang, J. Y. Nie, G. Ou, N. Sai, R. C. Shang, X. Y. Song, L. Sun, Y. Tan, L. Tao, C. Wang, G. F. Wang, J. Wang, J. B. Wang, M. Wang, N. Wang, W. S. Wang, Y. D. Wang, Y. S. Wang, X. Y. Wen, Z. G. Wen, B. B. Wu, B. Y. Wu, M. Wu, G. C. Xiao, S. Xiao, S. L. Xiong, Y. H. Xu, W. M. Yan, J. W. Yang, S. Yang, Y. J. Yang, Q. B. Yi, Q. Q. Yin, Y. You, Y. L. Yue, A. M. Zhang, C. M. Zhang, D. P. Zhang, F. Zhang, H. M. Zhang, J. Zhang, T. Zhang, W. C. Zhang, W. Zhang, W. Z. Zhang, Y. Zhang, Y. F. Zhang, Y. J. Zhang, Z. Zhang, Z. L. Zhang, H. S. Zhao, X. F. Zhao, W. Zheng, D. K. Zhou, J. F. Zhou, X. Zhou, R. L. Zhuang, Y. X. Zhu, and Y. Zhu

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010504 meteorology & atmospheric sciences, Crab Pulsar, Astrophysics::High Energy Astrophysical Phenomena, Total frequency, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Glitch, Stars, Crab Nebula, Amplitude, Pulsar, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Spin-up, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Glitches correspond to sudden jumps of rotation frequency ($\nu$) and its derivative ($\dot{\nu}$) of pulsars, the origin of which remains not well understood yet, partly because the jump processes of most glitches are not well time-resolved. There are three large glitches of the Crab pulsar, detected in 1989, 1996 and 2017, which were found to have delayed spin-up processes before the normal recovery processes. Here we report two additional glitches of the Crab pulsar occurred in 2004 and 2011 for which we discovered delayed spin up processes, and present refined parameters of the largest glitch occurred in 2017. The initial rising time of the glitch is determined as $, Comment: 25 pages, 8 figures

Published
2020
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26. Absolute calibration of LHAASO WFCTA camera based on LED

Author

W. J. Long, Rong Xu, Cong Li, J. J. Xia, Houdun Zeng, Axikegu, Yongchun Wang, H. H. He, Xufang Li, X. X. Zhai, Y. D. Cui, L. Feng, H. B. Li, F. R. Zhu, Qie Sun, Yi Chen, F. Y. Li, C. F. Feng, D. H. Huang, Bin Zhou, J. Y. Shi, V. I. Stepanov, H. Zhu, Jun-Jie Wei, L. Z. Zhao, F. Ji, M. Zha, Jia Zhang, Y. H. Yao, Yi Zhang, B. Q. Qiao, Rui Zhang, Linbin Yang, Zhengguo Cao, M. L. Chen, Jianeng Zhou, Jian Wang, Chiming Jin, Zhe Cao, M. M. Ge, X. Zuo, Xuliang Chen, D.A. Kuleshov, Hong-Guang Wang, Y. He, Xiang-Yu Wang, E. S. Chen, Y. A. Han, N. Cheng, J. Fang, S. Hu, J. Y. Liu, G. M. Xiang, H. C. Song, S. P. Zhao, Zebo Tang, H. B. Xiao, W. Liu, L. X. Bai, Binyu Zhao, Yun-Feng Liang, Tao Zeng, Jixia Li, W. Zeng, Bin Ma, Donglian Xu, Z. Min, Xuelong Wang, Xiaofei Zhang, X. L. Guo, X. J. Dong, Hefan Li, S. H. Feng, Q. H. Chen, G. G. Xin, Warit Mitthumsiri, Kai-Kai Duan, Ying Zhang, P. F. Zhang, Z. X. Wang, H.Y. Gan, T. Wen, S. W. Cui, K. Levochkin, Hao Zhou, W. Wang, P. Pattarakijwanich, Kun Fang, D. M. Wei, H. Cai, S. Wu, Sina Chen, X. D. Sheng, Minghao Qi, C. X. Liu, Y. L. Feng, D. Bastieri, Q. An, B. Y. Pang, B. Liu, B. D. Wang, T. Ke, S. B. Yang, Bai Yibing, Lidan Gao, Y. W. Bao, Y. C. Nan, S. Z. Chen, Zhe Li, Shi-Qi Hu, X. H. You, H. B. Hu, H. Liu, X. T. Huang, J. C. He, Bingshui Gao, R. Zhou, L. Y. Wang, Z. H. Wang, Li Zhang, Z. G. Dai, M. J. Yang, Fan Yang, A. Masood, David Ruffolo, C. W. Yang, Q. Gao, Jun Liu, Z. K. Zeng, C. D. Gao, Lei Zhao, Z. C. Huang, B. B. Li, G. H. Gong, Lang Shao, M. J. Chen, Y. J. Wang, H. M. Zhang, D. della Volpe, He Zhang, Jianguo Qin, Y. J. Bi, Jun-Hui Fan, H. D. Liu, W. H. Huang, Y. D. Cheng, Z. B. Sun, Bo Zhang, Duo Yan, Z. X. Liu, Ruizhi Yang, X. N. Sun, Li-Sheng Geng, S. L. He, W. L. Li, Y. P. Wang, Y. H. Yu, Z. G. Yao, D. X. Xiao, J.W. Xia, X. G. Wang, H. L. Dai, Y. Y. Guo, Danzengluobu, Y. Q. Qi, H. Wang, W. Gao, Yi Liu, J. B. Zhao, Y. K. Hor, J. Chen, Zheng Wang, Q. B. Gou, L. P. Wang, Qizhi Huang, T. L. Chen, X. F. Wu, X. L. Ji, R. Lu, Cheng Guang Zhu, Zhuo Li, T. Montaruli, S. Q. Xi, Zhen Wang, Y.T. Fu, G. C. Xiao, Y. Z. Fan, X. H. Cui, Z. Y. Pei, B. D'Ettorre Piazzoli, W. X. Wu, H. Y. Jia, Y. Wang, B. Z. Dai, Alejandro Sáiz, Youping Li, J. T. Cai, R. Liu, Long Chen, Y. J. Wei, Fengqin Guo, J. F. Chang, V. Rulev, L. Xue, Liang Chen, Y. L. Xin, Yugang Zhang, Xinbo He, K. Jiang, X. J. Bi, X. J. Hu, Y. Zheng, L. Q. Yin, X. Y. Huang, J. W. Zhang, P. P. Zhang, Wenwu Tian, Pak-Hin Thomas Tam, H. C. Li, Z. X. Fan, Z. Y. You, J. Y. Yang, Ping Zhou, Junjie Mao, Y. Z. Li, F. Zheng, Y. Q. Guo, H. R. Wu, B. M. Chen, X. X. Zhou, Q. Yuan, Felix Aharonian, H. N. He, M. Heller, K. Li, L. L. Ma, Yu. V. Stenkin, Z. J. Jiang, J. Liu, Yong Zhang, R. N. Wang, C. Hou, Shuibin Lin, S. M. Liu, Lu Zhang, J. S. Wang, Cunguo Wang, E. W. Liang, N. Yin, K. J. Zhu, Minghui Liu, Shengxue Zhang, Cheng Li, Dong Liu, Jinyao Liu, C. Y. Wu, Y. M. Ye, Yunchao Liu, Y. M. Xing, H. K. Lv, X. H. Ma, Xiang Zhang, Y. Su, J. G. Guo, S. R. Zhang, M. H. Gu, L. X. Zhang, Jiawei Yan, Xin Li, and Oleg Shchegolev

Subjects
Physics, Nuclear and High Energy Physics, Photon, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Cosmic ray, Metrology, law.invention, Telescope, Air shower, Silicon photomultiplier, Optics, law, Calibration, business, Instrumentation, Cherenkov radiation
Abstract

The main scientific goal of the LHAASO WFCTA experiment is to measure the cosmic ray energy spectra and composition from 10 TeV to 1 EeV. Cherenkov photons in the extensive air shower measured by the SiPM camera of Cherenkov telescopes can be used to reconstruct the cosmic ray energy. The absolute calibration of the camera is a crucial step to achieve the accurate measurement of the cosmic ray energy spectrum. A multi-wavelength cylindrical illuminator based on LEDs is developed and mounted inside the telescope to calibrate and monitor the camera, and the illuminator’s stability is better than 0.5% under the temperature variation from -26 to 26 ° C. A portable probe with a single photoelectron resolution of 21.6% is developed. After calibration by National Institute of Metrology, China (NIM), the probe is taken to the LHAASO site to measure the absolute photon density of the cylindrical illuminator inside the telescope. Based on the illuminator with known photon density, the photon conversion factor of the camera can be calibrated, and the overall calibration uncertainty is less than 2.6%.

Published
2022

27. An apparatus to measure water optical attenuation length for LHAASO-MD

Author

L. P. Wang, Zhihao Duan, Cong Li, Jia Liu, S. H. Feng, Hui Wang, Xiong Zuo, Mohsin Saeed, Xiurong Li, Huihai He, N. Cheng, G. C. Xiao, and Bo Gao

Subjects
Physics, Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, 010308 nuclear & particles physics, business.industry, Attenuation, Detector, Attenuation length, Cosmic ray, 01 natural sciences, Wavelength, Air shower, Optics, Observatory, 0103 physical sciences, Calibration, High Energy Physics::Experiment, 010306 general physics, business, Instrumentation, Physics::Atmospheric and Oceanic Physics
Abstract

The large high altitude air shower observatory (LHAASO) is being constructed at 4400 m a.s.l. in Daocheng, Sichuan Province, aiming to reveal the secrets of cosmic rays origin. And it has the largest surface muon detector array in the world. Due to the needs of calibration and construction of muon detector, we developed a water optical attenuation measurement device using an 8 m long water tank. The results are presented for filtered water at wavelength of 405 nm, which proves this apparatus can reach an accuracy of about 20% at 100 m. This apparatus has not only a high precision measurement of water attenuation length up to 100 m but is also very convenient to be used, which is crucial for water optical properties study during LHAASO detector construction.

Published
2018

28. A calibration of WFCTA prototype telescopes using N2 laser

Author

M. H. Gu, G. C. Xiao, S. H. Feng, Zihuang Cao, M. Zha, L. L. Ma, M. J. Chen, Bin Zhou, J. Liu, X. Zuo, H. Y. Jia, Bai Yibing, Bingshui Gao, Shengxue Zhang, C. Hou, J. B. Zhao, S. Z. Chen, B.K. Zhang, H. H. He, Y. Zhang, Jiali Liu, and F. R. Zhu

Subjects
Physics, Nuclear and High Energy Physics, Photon, 010308 nuclear & particles physics, business.industry, Scattering, Aperture, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Field of view, Laser, 01 natural sciences, law.invention, 010309 optics, Telescope, Optics, law, 0103 physical sciences, Calibration, business, Instrumentation
Abstract

An end-to-end calibration method, which is different from the traditional way, has been employed in WFCTA prototype experiment based on N 2 laser. As we known, the calculation of the expected and the observed light fluxes at the front of the aperture of the telescope are crucial in the such method. To calculate predicted light flux accurately, the propagation and scattering of photons in the atmosphere have been considered in detail. In order to get the detector effective areas, which will be used in the transformation of ADC signals to the observed light flux, a ray trace procedure, considering all details of detector response, has been performed for all incident direction of photons in field of view of the detector. By matching the observed and expected light flux at the entrance of the telescope, the overall calibration gains of two telescopes can be obtained. During the test run of the calibration, a overall calibration gain around G = 0 . 38 A D C c o u n t s ∕ p h o t o n and G = 0 . 36 A D C c o u n t s ∕ p h o t o n for WFCT01 and WFCT02 are given, respectively. Furthermore, in view of all uncertainty sources, systematic uncertainties for the calibration have also been estimated. They are around the level of ( − 7 . 3 % , + 7 . 8 % ) . The calibration results achieved by end-to-end method and the traditional way are in consistent at the level of 10%, which is within the range of uncertainties. Since the end-to-end and traditional calibration methods have their own advantages, the performance of the combination of these two calibration methods has also been discussed in the end.

Published
2018

29. Calibration and monitoring of LHAASO-KM2A muon detectors with muon decay events

Author

Huihai He, Xiong Zuo, Wei Wang, Jinfan Chang, Hongkui Lv, Jia Liu, Cong Li, Guanghua Gong, N. Cheng, Mohsin Saeed, Bin Hong, S. H. Feng, Hongming Li, Minghao Gu, G. C. Xiao, Xiangdong Sheng, Xiurong Li, Fei Li, and S. R. Zhang

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Muon, Physics::Instrumentation and Detectors, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Cosmic ray, Charge (physics), Electron, 01 natural sciences, Nuclear physics, Air shower, Observatory, 0103 physical sciences, Calibration, High Energy Physics::Experiment, 010303 astronomy & astrophysics, Instrumentation, Energy (signal processing)
Abstract

The Large High Altitude Air Shower Observatory (LHAASO) will be constructed at 4400 m asl in Daocheng, Sichuan Province, with the aim of discovering sources of ultra-high energy cosmic rays and studying cosmic ray physics. The whole array includes 1171 muon detectors (MDs), constituting the largest muon detector array in the world. The special high altitude and wide-field environment requires simple and stable calibration as well as monitoring method of MDs. In this paper, the muon decay events will be selected for calibrating the charge and monitoring the water level of each MD. In the prototype muon detector, the simulation and experiment results reveal that the charge of the decay electron is approximately 0.147 times that of the vertical equivalent muon for a standard MD, and the Q V E M ∕ Q e shows a linear correlation with the water level.

Published
2018

30. Study on the Energy Limits of kHz QPOs in Sco X-1 with RXTE and Insight-HXMT Observations

Author

Lian Tao, G. C. Xiao, Yupeng Xu, Yong Chen, Fangjun Lu, Yu Huang, C. Z. Liu, Shu Zhang, Xiang Ma, Shu-Mei Jia, D. K. Zhou, Li-Ming Song, Qingcui Bu, X. L. Cao, Shuang-Nan Zhang, Li Chen, D. H. Wang, and Jin-Lu Qu

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010504 meteorology & atmospheric sciences, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, X-ray binary, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Horizontal branch, 01 natural sciences, Spectral line, law.invention, Telescope, Root mean square, Neutron star, Amplitude, Space and Planetary Science, law, 0103 physical sciences, Modulation (music), Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

We present a detailed spectral-timing analysis of the Kilohertz quasiperiodic oscillations (kHz QPOs) in Sco X-1 using the data of the Rossi X-ray Timing Explorer (RXTE) and the Hard X-ray Modulation Telescope (Insight-HXMT). The energy band with detectable kHz QPOs is studied for the first time: on the horizontal branch, it is ∼6.89–24.01 and ∼8.68–21.78 keV for the upper and lower kHz QPOs, respectively, detected by the RXTE, and ∼9–27.5 keV for the upper kHz QPOs by the Insight-HXMT; on the lower normal branch, the energy band is narrower. The fractional root mean square (rms) of the kHz QPOs increases with energy at a lower energy, reaches a plateau at about 16 and 20 keV for the lower and upper peaks, and then levels off though with a large uncertainty. The simulation of the deadtime effect of RXTE/PCA shows that the deadtime does not affect much the search of the kHz QPOs but makes the rms amplitude underestimated. No significant QPO is detected below ∼6 keV as shown by the RXTE data, implying that the kHz QPOs do not originate from the blackbody emission of the accretion disk and neutron star surface. In addition, with the combined analysis of the energy spectra and the absolute rms spectra of kHz QPOs, we suggest that the kHz QPOs in Sco X-1 originate from the Comptonization of the inner part of the transition layer, where the rotation sets the frequency and the inward bulk motion makes the spectrum harder.

Published
2021

31. Hot disk of the Swift J0243.6+6124 revealed by Insight-HXMT

Author

J. K. Deng, X. H. Ma, B. B. Wu, Min Gao, Lian Tao, L. Chen, Yi-Yan Yang, X. Y. Song, C. L. Zhang, Xue-Feng Lu, Shuinai Zhang, H. S. Zhao, S. M. Jia, C. Z. Liu, M. X. Fu, Y. Nang, Ya Fang Huang, Tao Luo, Wan-Chang Zhang, Bin Meng, Mao-Shun Li, Sisi Yang, X. X. Li, L. J. Qu, J. Z. Wang, Y. L. Tuo, G. F. Wang, J. W. Yang, W. C. Jiang, Tian-Xiang Chen, Weiguang Cui, Qingcui Bu, Yunchao Liu, Y. J. Jin, L. M. Song, Sergey S. Tsygankov, Y. J. Yang, V. Doroshenko, Ti-Pei Li, F. Zhang, Yuan-Yuan Du, S. J. Zheng, Gang Chen, W. S. Wang, J. Y. Liao, H. M. Zhang, Junke Zhang, Wenxiong Li, Qing-He Zhang, Ge Ou, Da-Wei Han, XiangYang Wen, J. Y. Nie, Y. F. Zhang, Andrea Santangelo, Shaolin Xiong, Bo Lu, J. Jin, Y. J. Zhang, Xuchao Zhao, H. Gao, W. Z. Zhang, Wei Zhang, G. H. Gao, Yi-Qiao Dong, Y. H. Tan, Cheng-Cheng Guo, M. Wu, Y. Zhang, Fangjun Lu, Y. B. Chen, Alexander A. Mushtukov, Z. Zhang, Long Ji, Y. P. Chen, Bing Li, Y. S. Wang, T. Zhang, Chun-sheng Zhang, Xiaobo Li, W. Hu, X. F. Li, X. H. Liang, C. L. Zou, Z. L. Zhang, C. K. Li, G. C. Xiao, H. Xu, Y. X. Zhu, Z. W. Li, Ming-Yu Ge, Z. J. Li, ShaoZhen Liu, L. D. Kong, Yidong Xu, Yu-Dong Gu, S. N. Zhang, Jia Huo, Gang Li, X. L. Cao, J. Zhao, J. Guan, Aimei Zhang, GuoQing Liu, Wei Cui, Yu-Xuan Zhu, X. J. Liu, Liang Sun, Y. G. Li, Luhua Jiang, Z. Chang, Yujuan Liu, H. W. Liu, and N. Sai

Subjects
Swift, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Magnetosphere, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Pulsar, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, computer.programming_language, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Scattering, Spectral properties, Astronomy and Astrophysics, Accretion (astrophysics), Neutron star, Radiation pressure, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, computer
Abstract

We report on analysis of observations of the bright transient X-ray pulsar \src obtained during its 2017-2018 giant outburst with Insight-HXMT, \emph{NuSTAR}, and \textit{Swift} observatories. We focus on the discovery of a sharp state transition of the timing and spectral properties of the source at super-Eddington accretion rates, which we associate with the transition of the accretion disk to a radiation pressure dominated (RPD) state, the first ever directly observed for magnetized neutron star. This transition occurs at slightly higher luminosity compared to already reported transition of the source from sub- to super-critical accretion regime associate with onset of an accretion column. We argue that this scenario can only be realized for comparatively weakly magnetized neutron star, not dissimilar to other ultra-luminous X-ray pulsars (ULPs), which accrete at similar rates. Further evidence for this conclusion is provided by the non-detection of the transition to the propeller state in quiescence which strongly implies compact magnetosphere and thus rules out magnetar-like fields., Submitted to MNRAS

Published
2019

32. Timing analysis of 2S 1417-624 observed with NICER and Insight-HXMT

Author

Tao Luo, J. Y. Zhang, B. B. Wu, G. H. Gao, Z. L. Zhang, Gang Chen, M. Wu, Y. Zhang, C. K. Li, Wei Zhang, Y. P. Chen, Y. H. Tan, Yi-Qiao Dong, H. Xu, Y. J. Jin, Victor Doroshenko, Shaolin Xiong, Z. W. Li, Cheng-Cheng Guo, F. J. Lu, Ya Fang Huang, Bo Li, Y. J. Zhang, J. Jin, J. K. Deng, H. Gao, L. Chen, Yi-Yan Yang, J. Y. Liao, H. M. Zhang, Tian-Xiang Chen, Yunchao Liu, XiangYang Wen, X. X. Li, Y. F. Zhang, X. B. Li, X. H. Ma, Can Güngör, Li-Ming Song, Xue-Feng Lu, Suo Liu, Xuchao Zhao, W. C. Zhang, Y. S. Wang, J. Zhao, Y. Nang, J. Y. Nie, S. J. Zheng, Mao-Shun Li, Lian Tao, X. H. Liang, L. Sun, Y. G. Li, Qing-He Zhang, Y. L. Tuo, Aimei Zhang, J. W. Yang, C. Z. Liu, S. M. Jia, X. Y. Song, Y. B. Chen, Luhua Jiang, W. Hu, L. J. Qu, H. W. Liu, Sisi Yang, Yu-Xuan Zhu, Z. Zhang, Long Ji, N. Sai, Yuan-Yuan Du, Chun-sheng Zhang, Wenhan Jiang, C. L. Zou, Yupeng Xu, X. J. Liu, X. L. Cao, Z. Chang, C. L. Zhang, Yujuan Liu, Wenxiong Li, B. Lu, S. N. Zhang, Andrea Santangelo, Y. X. Zhu, Ming-Yu Ge, Jia Huo, Gang Li, Lorenzo Ducci, Wei Cui, T. Zhang, W. Z. Zhang, Ti-Pei Li, Xuelong Li, J. Guan, Z. J. Li, L. D. Kong, GuoQing Liu, Bin Meng, Yu-Dong Gu, Y. J. Yang, G. C. Xiao, Fuqin Zhang, W. S. Wang, Ge Ou, Da-Wei Han, Min Gao, H. S. Zhao, M. X. Fu, J. Z. Wang, Weiguang Cui, G. F. Wang, and Qingcui Bu

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Accretion (meteorology), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Theoretical models, FOS: Physical sciences, Static timing analysis, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radiation, 01 natural sciences, Luminosity, Magnetic field, QC Physics, Pulsar, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Fermi Gamma-ray Space Telescope
Abstract

We present a study of timing properties of the accreting pulsar 2S 1417-624 observed during its 2018 outburst, based on Swift/BAT, Fermi/GBM, Insight-HXMT and NICER observations. We report a dramatic change of the pulse profiles with luminosity. The morphology of the profile in the range 0.2-10.0keV switches from double to triple peaks at $\sim2.5$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$ and from triple to quadruple peaks at $\sim7$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$. The profile at high energies (25-100keV) shows significant evolutions as well. We explain this phenomenon according to existing theoretical models. We argue that the first change is related to the transition from the sub to the super-critical accretion regime, while the second to the transition of the accretion disc from the gas-dominated to the radiation pressure-dominated state. Considering the spin-up as well due to the accretion torque, this interpretation allows to estimate the magnetic field self-consistently at $\sim7\times 10^{12}$G., 7 pages, 4 figures, 1 tables, accepted for publication in MNRAS

Published
2019

33. LHAASO KM2A Muon Detector On-site Test System

Author

L. P. Wang, Guangguang Xin, Xiong Zuo, Cong Li, N. Cheng, Hongliang Dai, G. C. Xiao, Shiping Zhao, Hui Wang, Zhe Li, and Yi Zhang

Subjects
Physics, Physics::Instrumentation and Detectors, business.industry, Cherenkov detector, Detector, Scintillator, law.invention, Telescope, Overburden, Optics, Air shower, Data acquisition, law, Observatory, business
Abstract

The Muon detector (MD) of LHAASO-KM2A (Large High-Altitude Air Shower Observatory 1km2 Array) [1] is a water Cherenkov detector with an effective area of ~36 m2. The 2.5 m thick overburden soil is used as a shield to prevent low energy electromagnetic particles from reaching water. Each MD must be well tested before the covering process of the thick soil. In this case, the on-site test system is designed and manufactured, consisting of a telescope and a data acquisition system. The telescope is a combination of two vertically placed scintillator detectors covered by 4cm thick lead each. Charge resolution and time resolution are estimated by analysing the test data. In addition, waveforms of the MD signal are recorded each second, which will serve to evaluate the water quality of MD.

Published
2019

34. Study on the muon lateral distribution based on the first stage of LHAASO-KM2A

Author

Cong Li, Xiong Zuo, Youliang Feng, Yi Zhang, N. Cheng, Shiping Zhao, L. P. Wang, Y. Y. Guo, G. C. Xiao, and G. G. Xin

Subjects
Physics, Nuclear physics, Muon, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, High Energy Physics::Experiment, Cosmic ray, Stage (hydrology), Gamma-ray astronomy, Muon detector
Abstract

The first stage of LHAASO-KM2A has been completed in Sichuan, China. KM2A is composed of electromagnetic particle detectors (ED) and muon detectors (MD), focusing on gamma ray astronomy above 30 TeV and cosmic ray physics in the “knee” region. The ED array in the first stage is installed into two clusters and the distance between the two clusters is around 230 meters. The MDs are distributed in one of the clusters. Each MD is covered with soil of 2.5 meters thick. We analyzed the lateral distribution of muons which are 140-300 meters away from Shower axis, and the primary cosmic ray energy is about 100TeV.

Published
2019

35. Insight-HXMT Observations of a Possible Fast Transition from the Jet- to Wind-dominated State during a Huge Flare of GRS 1915+105

Author

R. J. Yang, Qiu-Yi Luo, L. Chen, H. S. Zhao, Y. L. Tuo, J. Y. Liao, H. M. Zhang, Y. Nang, Lei Sun, C. Z. Liu, Lian Tao, D. K. Zhou, R. C. Ma, Y. F. Zhang, Yuan You, Y. H. Zhang, X. Y. Song, X. H. Ma, Yuan-Yuan Du, Qi-Bin Yi, B. Y. Wu, P. J. Wang, Tao Luo, Bo Liu, B. B. Wu, Xuelong Li, J. Guan, Li-Ming Song, S. Xiao, Bo Li, Shaolin Xiong, X. X. Li, Xue-Feng Lu, H. Gao, G. H. Gao, Tong Li, S. M. Jia, Y. P. Xu, Sisi Yang, S. J. Zheng, F. J. Lu, M. Wu, Jia Huo, XiangYang Wen, Y. H. Tan, Ya Fang Huang, Peng Zhang, Qingcui Bu, Y. G. Zheng, H. W. Liu, Y. J. Yang, X. L. Cao, Gang Li, W. S. Wang, Tian-Xiang Chen, N. Sai, Cunguo Wang, C. K. Li, Ge Ou, W. C. Zhang, S. N. Zhang, Y. B. Chen, Junqiang Zhang, Q. Q. Yin, Z. W. Li, Y. P. Chen, G. C. Xiao, J. Jin, Xin-Fu Zhao, X. J. Liu, Y. S. Wang, Wenhan Jiang, Ling-Jun Wang, C. Cai, Wenxiong Li, Gang Chen, Z. Chang, Da-Wei Han, L. D. Kong, Xiong Li, Yu-Dong Gu, Bin Meng, Min Gao, Ming-Yu Ge, X. H. Liang, J. L. Qu, Hongfei Liu, Fuqin Zhang, Long Ji, X. Q. Ren, Wei Cui, J. Y. Nie, Wei Zhang, and Cheng-Cheng Guo

Subjects
010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, X-ray binary, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Spectral line, Luminosity, law.invention, Astrophysical jet, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Accretion (meteorology), Astronomy and Astrophysics, Radius, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Energy (signal processing), Flare
Abstract

We present the analysis of the brightest flare that was recorded in the \emph{Insight}-HMXT data set, in a broad energy range (2$-$200 keV) from the microquasar GRS~1915+105 during an unusual low-luminosity state. This flare was detected by \emph{Insight}-HXMT among a series of flares during 2 June 2019 UTC 16:37:06 to 20:11:36, with a 2-200 keV luminosity of 3.4$-$7.27$\times10^{38}$ erg s$^{-1}$. Basing on the broad-band spectral analysis, we find that the flare spectrum shows different behaviors during bright and faint epochs. The spectrum of the flare can be fitted with a model dominated by a power-law component. Additional components show up in the bright epoch with a hard tail and in the faint epoch with an absorption line $\sim$ 6.78 keV. The reflection component of the latter is consistent with an inner disk radius $\sim$ 5 times larger than that of the former. These results on the giant flare during the "unusual" low-luminosity state of GRS~1915+105 may suggest that the source experiences a possible fast transition from a jet-dominated state to a wind-dominated state. We speculate that the evolving accretion disk and the large-scale magnetic field may play important roles in this peculiar huge flare.

Published
2021

36. Two Complete Spectral Transitions of Swift J0243.6+6124 Observed by Insight-HXMT

Author

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

Subjects
Physics, Swift, X-ray astronomy, Space and Planetary Science, X-ray binary, Astronomy and Astrophysics, Astrophysics, computer, Spectral line, Luminosity, computer.programming_language
Published
2020

37. Measuring the optical parameters for LHAASO-MD

Author

S. H. Feng, Xiong Zuo, G. C. Xiao, Huihai He, Cong Li, Hui Wang, Xiurong Li, Yuelei Zhang, Wenxiong Wu, N. Cheng, Huan-Yu Jia, L. P. Wang, and Yi Zhang

Subjects
Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, Cherenkov detector, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Measure (physics), 01 natural sciences, law.invention, Optics, law, Observatory, 0103 physical sciences, Detector array, 010303 astronomy & astrophysics, Instrumentation, Physics::Atmospheric and Oceanic Physics, media_common, Physics, 010308 nuclear & particles physics, business.industry, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Air shower, Sky, High Energy Physics::Experiment, business, Muon detector
Abstract

The Large High Altitude Air Shower Observatory (LHAASO) is a hybrid detector array, which will be capable of surveying the north VHE gamma-ray sky from 100 GeV to 1 PeV. The muon detector is a kind of water Cherenkov detector; thus, its optical properties are crucial for construction and understanding of the detector. We designed a series of methods to measure the optical parameters of water and inner layer, and the results from different methods are consistent with each other, which proves the reliability of the measurement results and provides an improved understanding of the detector.

Published
2020

38. Measurement of muonic and electromagnetic components in cosmic ray air showers using LHAASO-KM2A prototype array

Author

Cong Li, Yuncheng Nan, Jinfan Chang, Hongkui Lv, Hongming Li, Guanghua Gong, S. Z. Chen, Zhe Li, Xiong Zuo, Wei Wang, Huihai He, G. C. Xiao, Hui Wang, Xiurong Li, Minghao Gu, N. Cheng, Wei Gao, Yi Zhang, L. P. Wang, Mohsin Saeed, S. H. Feng, Jia Liu, Xiangdong Sheng, Sha Wu, S. R. Zhang, and Fei Li

Subjects
Physics, Nuclear physics, 010308 nuclear & particles physics, 0103 physical sciences, Cosmic ray, 010306 general physics, 01 natural sciences
Published
2018

39. Novel methods for measuring the optical parameters of the water Cherenkov detector

Author

Huihai He, Xiong Zuo, Cong Li, Zhengguo Cao, S. H. Feng, Xiangdong Sheng, N. Cheng, Mohsin Saeed, Xiurong Li, L. P. Wang, and G. C. Xiao

Subjects
Nuclear and High Energy Physics, Photomultiplier, Physics - Instrumentation and Detectors, Photon, Absorption of water, Cherenkov detector, Physics::Instrumentation and Detectors, FOS: Physical sciences, Applied Physics (physics.app-ph), 01 natural sciences, law.invention, Optics, law, 0103 physical sciences, 010306 general physics, Instrumentation, Physics, 010308 nuclear & particles physics, business.industry, Attenuation length, Physics - Applied Physics, Instrumentation and Detectors (physics.ins-det), Tyvek, Reflection (physics), Diffuse reflection, business
Abstract

In this paper, novel methods are presented to measure the optical properties of muon detectors (MDs) in the Large High-Altitude Air Shower Observatory (LHAASO), which can also be used by other experiments. Each MD consists of a cylindrical water Cherenkov detector, with a Tyvek liner containing pure water, and a photomultiplier tube (PMT) mounted on the top. The time distribution of the photons collected by the PMT in the water Cherenkov detector have an approximately exponential distribution, and their decay factor is determined by the photon absorption length in the water, the reflectivity of the inner Tyvek surface, the mean reflecting step length of photons reflected by the inner surface, and the ratio of reflectional Tyvek area to the total inner surface area. By considering the principles of photon propagation in the water Cherenkov detector, we have developed novel methods to measure the water absorption length, the Tyvek reflectivity, and the mean step length of photons. The step length of photons can be determined by measuring the time distribution of the reflected photons hitting the PMT after multiple photons with single wavelength are generated in the tank, with slightly different ratios of the inner Tyvek to the total inner area. The water absorption length and Tyvek reflectivity can be measured simultaneously by the PMT by changing the height of the water, while the step length and Tyvek reflectivity in air can also be measured simultaneously. The proposed novel methods are supported by deduction of formulae and verified by GEANT4 simulations and the prototype experiment.

Published
2018
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40. Insight-HXMT observations of the New Black Hole Candidate MAXI J1535-571: timing analysis

Author

Wei Zhang, Yi-Qiao Dong, Cheng-Cheng Guo, X. L. Cao, Fu-Guo Xie, Xian Hou, Yupeng Xu, Jiancheng Wang, Xian Li, Jundan Nie, Y. G. Li, Yunchao Liu, Z. Chang, Yujuan Liu, C. L. Zou, Luhua Jiang, Y. J. Yang, W. C. Jiang, C. Z. Liu, Wei Cui, Mao-Shun Li, J. K. Deng, J. F. Zhou, Tianmeng Zhang, B. B. Wu, Jia Huo, X. H. Ma, Ju Guan, J. F. Ji, Xiaobo Li, ShaoZhen Liu, Tianran Chen, Shan-Shan Weng, Gang Chen, Yu-Dong Gu, Lian Tao, Y. X. Zhu, Li-Ming Song, Ming-Yu Ge, Xiao-Jing Liu, Bing Li, Guobao Zhang, Xue-Feng Lu, H. W. Liu, Shuinai Zhang, W. Z. Zhang, Yuan-Yuan Du, Z. L. Zhang, Y. S. Wang, Wenxiong Li, GuoQing Liu, Y. H. Tan, L. Chen, Wenfei Yu, Hsiang-Kuang Chang, S. N. Zhang, Chuan-Peng Zhang, Ya Fang Huang, Y. Nang, C. L. Zhang, Limei Yan, S. Yang, G. H. Gao, Wan-Chang Zhang, Y. P. Chen, Can Güngör, Y. B. Chen, Ti-Pei Li, M. Wu, Y. Zhang, G. F. Wang, Y. L. Tuo, J. Y. Liao, H. M. Zhang, J. W. Yang, Y. F. Zhang, Bo Lu, Xuchao Zhao, M. X. Fu, Jia Zhang, C. K. Li, H. Wang, Wei Hu, Z. Zhang, X. X. Li, Weiguang Cui, Qing-He Zhang, Zhuo Li, Qingcui Bu, Shu-Mei Jia, W. S. Wang, Shaolin Xiong, HongSheng Zhao, H. Xu, Ge Ou, Y. J. Zhang, Z. W. Li, Da-Wei Han, H. Gao, S. J. Zheng, Tao Luo, X. H. Liang, Min Gao, J. Zhao, J. L. Qu, Liang Sun, Albert K. H. Kong, Aimei Zhang, Gang Li, N. Sai, Yu-Xuan Zhu, Bin Meng, Fangjun Lu, Y. J. Jin, J. Jin, R. C. Shang, WenHui Tao, G. C. Xiao, F. Zhang, and XiangYang Wen

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Static timing analysis, Centroid, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Phase lag, law.invention, Black hole, Telescope, Amplitude, Space and Planetary Science, law, 0103 physical sciences, Modulation (music), Intermediate state, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics
Abstract

We present the X-ray timing results of the new black hole candidate (BHC) MAXI J1535-571 during its 2017 outburst from Hard X-ray Modulation Telescope (\emph{Insight}-HXMT) observations taken from 2017 September 6 to 23. Following the definitions given by \citet{Belloni2010}, we find that the source exhibits state transitions from Low/Hard state (LHS) to Hard Intermediate state (HIMS) and eventually to Soft Intermediate state (SIMS). Quasi-periodic oscillations (QPOs) are found in the intermediate states, which suggest different types of QPOs. With the large effective area of \emph{Insight}-HXMT at high energies, we are able to present the energy dependence of the QPO amplitude and centroid frequency up to 100 keV which is rarely explored by previous satellites. We also find that the phase lag at the type-C QPOs centroid frequency is negative (soft lags) and strongly correlated with the centroid frequency. By assuming a geometrical origin of type-C QPOs, the source is consistent with being a high inclination system., Comment: 12 pages, 11 figures, Sumbitted to ApJ

Published
2018
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41. Design and performances of prototype muon detectors of LHAASO-KM2A

Author

Xiong Zuo, Wei Wang, Jia Liu, Xiangdong Sheng, Cong Li, Jinfan Chang, Minghao Gu, Guanghua Gong, Huihai He, S. R. Zhang, Hongming Li, S. H. Feng, Fei Li, G. C. Xiao, Hongkui Lv, Xiurong Li, and Bin Hong

Subjects
Physics, Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, Cherenkov detector, Astrophysics::High Energy Astrophysical Phenomena, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Cosmic ray, law.invention, Nuclear physics, Air shower, Muon collider, law, Observatory, High Energy Physics::Experiment, Cosmic-ray observatory, Instrumentation
Abstract

In the Large High Altitude Air Shower Observatory project, 1221 muon detectors will be built to discriminate cosmic gamma rays from nuclei and between cosmic ray species with energies in 10 13 – 10 18 eV . The muon detector has been designed to meet the physical requirements, according to which two muon detector prototypes have been built at the Yangbajing Cosmic Ray Observatory at the end of 2012 and in October 2014, respectively. The first one has been stably operated for more than 2 years. The performances of the two detectors have been evaluated, especially for position dependence and punch-through effect. In this paper, the design and the performances of the prototype muon detectors are presented.

Published
2015

42. An optical design of the telescope in the Wide Field of View Cherenkov/Fluorescence Telescope Array

Author

Bingkai Zhang, S. S. Zhang, Zhen Cao, Y. Zhang, Lingling Ma, M. Zha, Rui Yang, Jiali Liu, and G. C. Xiao

Subjects
Physics, business.industry, Distortion (optics), Astronomy and Astrophysics, Reflector (antenna), Radius, Curvature, Optical telescope, law.invention, Telescope, Optics, law, business, Spherical design, Cherenkov radiation
Abstract

Spherical design and Davies-cotton design, which can supply a wide Field of View (FOV) and have a single optical element structure, are the two candidate optics for Wide FOV Cherenkov/Fluorescence Telescope Array (WFCTA). To obtain a good imaging quality, we have done a detailed study to acquire optimal configurations for these two optics. In this paper, first, a proper curvature radius for the reflector, an optimized location for the camera, as well as a tolerance for the distortion of images for two designs have been presented. Furthermore, using such optimal configurations, the features of Cherenkov images initiated by proton and iron showers both with two optics have been investigated. Based on these results, it can be concluded that spherical design has the prior optical properties, such as a wider FOV of 16°, a higher and more homogeneous resolution for all incident directions within the 16° FOV and a lower light loss in the spots, as well as more signals collected in an Cherenkov image, relatively shorter arrival time difference for lights in a shower and brighter PMTs in the central part of a shower track. Thus it will be chosen as WFCTA optics. Finally, the optical properties of the two designs with 10° FOV have also been investigated. It should be mentioned that with such a smaller FOV, Davies-cotton optics is an effective design for it has a great imaging quality comparing with the setup of 16° FOV.

Published
2015

43. Insight-HXMT observations of the first binary neutron star merger GW170817

Author

Xufang Li, C. L. Zou, Yongjie Zhang, Yifei Zhang, Lian Tao, N. Sai, Ti-Pei Li, Shuang-Nan Zhang, Bin Meng, Aimei Zhang, Tong Zhang, Ming-Yu Ge, Xiao-Jing Liu, Yupeng Xu, Yuan Liu, Jing Jin, J. W. Yang, ShaoZhen Liu, Guan-Hua Gao, Xian Li, Sheng Yang, X. L. Cao, G. C. Xiao, Yong Chen, LinLi Yan, Shu-Mei Jia, Y. Tan, XiangYang Wen, W. C. Jiang, Yu-Dong Gu, Zheng-Wei Li, LuHua Jiang, L. Chen, M. X. Fu, W. S. Wang, Huanyu Wang, Wei-Wei Cui, Jianling Zhao, Yue Zhang, Yanji Yang, Juan Zhang, Yu-Xuan Zhu, Mao-Shun Li, Tian-Xiang Chen, Shaolin Xiong, Ju Guan, Jianyin Nie, Ge Ou, Wei Li, Cheng-Cheng Guo, Liang Sun, Bing Li, Wei Cui, Cheng-Kui Li, Yu-Peng Chen, Fan Zhang, H. Gao, Jin-Lu Qu, Yi Zhang, Yuan-Yuan Du, Wei Hu, Xiao-Fan Zhao, Yongwei Dong, Yue Huang, Gang Chen, X. H. Liang, Yue Zhu, Fangjun Lu, WenHui Tao, Hai-Sheng Zhao, He Xu, Juan Wang, H. T. Liu, Y. B. Chen, Youli Tuo, T. Luo, Jia Huo, W. Z. Zhang, ZiJian Li, Zhao Zhang, Gang Li, Yu-Sa Wang, Mei Wu, Shu Zhang, J. Y. Liao, Wei Zhang, Bo Lu, Y. N. Liu, Zi-Liang Zhang, Zhi Chang, GuoQing Liu, Da-Wei Han, HongMei Zhang, YongJie Jin, Y. Nang, ChunLei Zhang, G. F. Wang, Xiang Ma, Yanguo Li, Li-Ming Song, Xue-Feng Lu, M. Gao, Shi-Jie Zheng, Qiang Zhang, Bobing Wu, C. L. Zhang, C. X. Liu, J. K. Deng, Wan-Chang Zhang, and Xiaobo Li

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, General Physics and Astronomy, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact star, 01 natural sciences, LIGO, law.invention, Telescope, Neutron star, law, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, 010306 general physics, Gamma-ray burst, 010303 astronomy & astrophysics, Fermi Gamma-ray Space Telescope
Abstract

Finding the electromagnetic (EM) counterpart of binary compact star merger, especially the binary neutron star (BNS) merger, is critically important for gravitational wave (GW) astronomy, cosmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and \textit{Fermi}/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope (HE) onboard \textit{Insight}-HXMT (Hard X-ray Modulation Telescope) is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart (SSS17a/AT2017gfo) with very large collection area ($\sim$1000 cm$^2$) and microsecond time resolution in 0.2-5 MeV. In addition, \textit{Insight}-HXMT quickly implemented a Target of Opportunity (ToO) observation to scan the GW localization area for potential X-ray emission from the GW source. Although it did not detect any significant high energy (0.2-5 MeV) radiation from GW170817, its observation helped to confirm the unexpected weak and soft nature of GRB 170817A. Meanwhile, \textit{Insight}-HXMT/HE provides one of the most stringent constraints (~10$^{-7}$ to 10$^{-6}$ erg/cm$^2$/s) for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of \textit{Insight}-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event., Comment: accepted by Science China - Physics, Mechanics & Astronomy. Planned to publish on Oct 17, but postponed due to a problem on pdf file

Published
2017
Full Text
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44. In-orbit Demonstration of X-Ray Pulsar Navigation with the Insight-HXMT Satellite

Author

S. J. Zheng, S. N. Zhang, F. J. Lu, W. B. Wang, Y. Gao, T. P. Li, L. M. Song, M. Y. Ge, D. W. Han, Y. Chen, Y. P. Xu, X. L. Cao, C. Z. Liu, S. Zhang, J. L. Qu, Z. Chang, G. Chen, L. Chen, T. X. Chen, Y. B. Chen, Y. P. Chen, W. Cui, W. W. Cui, J. K. Deng, Y. W. Dong, Y. Y. Du, M. X. Fu, G. H. Gao, H. Gao, M. Gao, Y. D. Gu, J. Guan, C. Gungor, C. C. Guo, W. Hu, Y. Huang, J. Huo, J. F. Ji, S. M. Jia, L. H. Jiang, W. C. Jiang, J. Jin, Y. J. Jin, B. Li, C. K. Li, G. Li, M. S. Li, W. Li, X. Li, X. B. Li, X. F. Li, Y. G. Li, Z. J. Li, Z. W. Li, X. H. Liang, J. Y. Liao, G. Q. Liu, H. W. Liu, S. Z. Liu, X. J. Liu, Y. Liu, Y. N. Liu, B. Lu, X. F. Lu, T. Luo, X. Ma, B. Meng, Y. Nang, J. Y. Nie, G Ou, N. Sai, R. C. Shang, L. Sun, Y. Tan, L. Tao, W. Tao, Y. L. Tuo, G. F. Wang, J. Wang, W. S. Wang, Y. S. Wang, X. Y. Wen, B. B. Wu, M. Wu, G. C. Xiao, S. L. Xiong, H. Xu, L. L. Yan, J. W. Yang, S. Yang, Y. J. Yang, A. M. Zhang, C. L. Zhang, C. M. Zhang, F. Zhang, H. M. Zhang, J. Zhang, Q. Zhang, T. Zhang, W. Zhang, W. C. Zhang, W. Z. Zhang, Y. Zhang, Y. F. Zhang, Y. J. Zhang, Z. Zhang, Z. L. Zhang, H. S. Zhao, J. L. Zhao, X. F. Zhao, Y. Zhu, Y. X. Zhu, and C. L. Zou

Subjects
Physics, High energy, Crab Pulsar, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, 01 natural sciences, law.invention, Telescope, Pulsar, Space and Planetary Science, law, 0103 physical sciences, Satellite, Astrophysics::Earth and Planetary Astrophysics, Orbit (control theory), Astrophysics - Instrumentation and Methods for Astrophysics, 010306 general physics, Observation data, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, X-ray pulsar
Abstract

In this work, we report the in-orbit demonstration of X-ray pulsar navigation with Insight-Hard X-ray Modulation Telescope (Insight-HXMT), which was launched on Jun. 15th, 2017. The new pulsar navigation method 'Significance Enhancement of Pulse-profile with Orbit-dynamics' (SEPO) is adopted to determine the orbit with observations of only one pulsar. In this test, the Crab pulsar is chosen and observed by Insight-HXMT from Aug. 31th to Sept. 5th in 2017. Using the 5-day-long observation data, the orbit of Insight-HXMT is determined successfully with the three telescopes onboard - High Energy X-ray Telescope (HE), Medium Energy X-ray Telescope (ME) and Low Energy X-ray Telescope (LE) - respectively. Combining all the data, the position and velocity of the Insight-HXMT are pinpointed to within 10 km (3 sigma) and 10 m/s (3 sigma), respectively., Accepted by the Astrophysical Journal Supplement

Published
2019

45. Performance of a prototype water Cherenkov detector for LHAASO project

Author

Zhe Cao, J.L. Liu, Ye Xu, Z. G. Zhao, M. Zha, B.K. Zhang, L.H. Chen, H. R. Wu, T.L. Chen, H. Y. Jia, W. P. Huang, Huihai He, G.X. Sun, S.W. Cui, B. Gao, Q.Y. Yang, Zhiguo Yao, C. Li, Q. J. Li, Danzengluobu, X.Y. Zhang, Zhen Cao, Y.J. Mao, J. F. Chang, L. Zhang, S. S. Zhang, Haoqi Lu, X.H. Ma, C.F. Feng, Jinsong Huang, X. J. Bi, Shenye Liu, J. Liu, Minhao Gu, B.Z. Dai, Y.T. Chen, Q. An, X. J. Hao, J. B. Zhao, Min Chen, S.R. Zhang, G. C. Xiao, K. J. Zhu, H. B. Hu, Bin Zhou, X. D. Sheng, Y. X. Bai, Y. Zhang, Guo-Ming Chen, and C. Y. Wu

Subjects
Physics, Nuclear and High Energy Physics, Photomultiplier, Physics::Instrumentation and Detectors, Cherenkov detector, Astrophysics::High Energy Astrophysical Phenomena, Detector, Monte Carlo method, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, law.invention, Nuclear physics, Air shower, law, Observatory, High Energy Physics::Experiment, Instrumentation, Cherenkov radiation, Remote sensing
Abstract

A large high-altitude air shower observatory is to be built at Yang-Ba-Jing, Tibet, China. One of its main purposes is to survey the northern sky for very-high-energy (above 100 GeV) gamma ray sources via its ground-based water Cherenkov detector array. To gain full knowledge of water Cherenkov technique in detecting air showers, a prototype water Cherenkov detector is built at the Institute of High Energy Physics, Beijing. The performance of the prototype water Cherenkov detector is studied by measuring its response to cosmic muons. The results are compared with those from a full Monte Carlo simulation to provide a series of information regarding the prototype detector in guiding electronics design and detector optimization. (C) 2011 Elsevier B.V. All rights reserved.

Published
2011

46. Properties and performance of two wide field of view Cherenkov/fluorescence telescope array prototypes

Author

M. J. Chen, M. Zha, K.Q. Ding, L. L. Ma, G. C. Xiao, S. S. Zhang, S. Z. Chen, X. D. Sheng, J. B. Zhao, Zhen Cao, Y. X. Bai, X.H. Ma, Jiali Liu, Yong Chen, Y. Zhang, J. Liu, X.X. Li, Huihai He, Bin Zhou, and L.H. Chen

Subjects
Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, Cherenkov detector, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, law.invention, Telescope, Optics, law, Observatory, Astrophysics::Solar and Stellar Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Instrumentation, Cherenkov radiation, Physics, business.industry, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Instrumentation and Detectors (physics.ins-det), Cherenkov Telescope Array, Wide field, Air shower, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, business
Abstract

A wide field of view Cherenkov/fluorescence telescope array is one of the main components of the Large High Altitude Air Shower Observatory project. To serve as Cherenkov and fluorescence detectors, a flexible and mobile design is adopted for easy reconfiguring of the telescope array. Two prototype telescopes have been constructed and successfully run at the site of the ARGO-YBJ experiment in Tibet. The features and performance of the telescopes are presented. (C) 2010 Elsevier B.V. All rights reserved.

Published
2011

47. Insight-HXMT Observations of 4U 1636-536: Corona Cooling Revealed with Single Short Type-I X-Ray Burst

Author

Y. P. Chen, S. Zhang, J. L. Qu, S. N. Zhang, L. Ji, L. D. Kong, X. L. Cao, Z. Chang, G. Chen, L. Chen, T. X. Chen, Y. Chen, Y. B. Chen, W. Cui, W. W. Cui, J. K. Deng, Y. W. Dong, Y. Y. Du, M. X. Fu, G. H. Gao, H. Gao, M. Gao, M. Y. Ge, Y. D. Gu, J. Guan, C. C. Guo, D. W. Han, W. Hu, Y. Huang, J. Huo, S. M. Jia, L. H. Jiang, W. C. Jiang, J. Jin, Y. J. Jin, B. Li, C. K. Li, G. Li, M. S. Li, T. P. Li, W. Li, X. Li, X. B. Li, X. F. Li, Y. G. Li, Z. J. Li, Z. W. Li, X. H. Liang, J. Y. Liao, C. Z. Liu, G. Q. Liu, H. W. Liu, S. Z. Liu, X. J. Liu, Y. Liu, Y. N. Liu, B. Lu, F. J. Lu, X. F. Lu, T. Luo, X. Ma, B. Meng, Y. Nang, J. Y. Nie, G. Ou, N. Sai, L. M. Song, L. Sun, Y. Tan, L. Tao, W. H. Tao, Y. L. Tuo, G. F. Wang, H. Y. Wang, J. Wang, W. S. Wang, Y. S. Wang, X. Y. Wen, B. B. Wu, M. Wu, G. C. Xiao, S. L. Xiong, H. Xu, Y. P. Xu, L. L. Yan, J. W. Yang, S. Yang, Y. J. Yang, A. M. Zhang, C. L. Zhang, C. M. Zhang, F. Zhang, H. M. Zhang, J. Zhang, Q. Zhang, T. Zhang, W. Zhang, W. C. Zhang, W. Z. Zhang, Y. Zhang, Y. F. Zhang, Y. J. Zhang, Z. Zhang, Z. L. Zhang, H. S. Zhao, J. L. Zhao, X. F. Zhao, S. J. Zheng, Y. Zhu, Y. X. Zhu, and C. L. Zou

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Broad bandwidth, Stacking, X-ray, FOS: Physical sciences, Astronomy and Astrophysics, Economic shortage, Astrophysics, 01 natural sciences, Corona, law.invention, Space and Planetary Science, law, 0103 physical sciences, Spectral fitting, Astrophysics - High Energy Astrophysical Phenomena, 010306 general physics, 010303 astronomy & astrophysics, Flare
Abstract

Corona cooling was detected previously from stacking a series of short type-I bursts occurred during the low/had state of atoll outburst. Type-I bursts are hence regarded as sharp probe to our better understanding on the basic property of the corona. The launch of the first Chinese X-ray satellite Insight-HXMT has large detection area at hard X-rays which provide almost unique chance to move further in this research field. We report the first detection of the corona cooling by Insight-HXMT from single short type-I burst showing up during {\bf flare} of 4U 1636-536. This type-I X-ray burst has a duration of $\sim$13 seconds and hard X-ray shortage is detected with significance 6.2~$\sigma$ in 40-70 keV. A cross-correlation analysis between the lightcurves of soft and hard X-ray band, shows that the corona shortage lag the burst emission by 1.6 $\pm$1.2~s. These results are consistent with those derived previously from stacking a large amount of bursts detected by RXTE/PCA within a series of {\bf flares} of 4U 1636-536. Moreover, the broad bandwidth of Insight-HXMT allows as well for the first time to infer the burst influence upon the continuum spectrum via performing the spectral fitting of the burst, which ends up with the finding that hard X-ray shortage appears at around 40 keV in the continuum spectrum. These results suggest that the evolution of the corona along with the outburst{\bf /flare} of NS XRB may be traced via looking into a series of embedded type-I bursts by using Insight-HXMT., Comment: published in 2018, ApJL,864, L30

Published
2018

48. Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes

Author

S. S. Zhang, F. Dulucq, B. Yun Ky, L.Q. Yin, L. Zhang, I. Lhenry-Yvon, Olivier Deligny, Zhen Cao, G. Martin-Chassard, Y. T. Chen, G. C. Xiao, Z. Zhu, E. Wanlin, H. Zhang, M. M. Ge, T. Nguyen Trung, C. de la Taille, T. Suomijärvi, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and LHAASO Collaboration

Subjects
Nuclear and High Energy Physics, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, IACT, Integrated circuit, Analog signal processing, 01 natural sciences, 7. Clean energy, law.invention, Computer Science::Hardware Architecture, Data acquisition, Application-specific integrated circuit, law, 0103 physical sciences, Electronics, Field-programmable gate array, 010303 astronomy & astrophysics, Instrumentation, 010302 applied physics, Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Cherenkov Telescope Array, business, Computer hardware
Abstract

International audience; In this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs.

Published
2015

49. Energy spectrum of cosmic protons and helium nuclei by a hybrid measurement at 4300 m a.s.l

Author

A. D'Amone, Bo Gao, Zhenyong Feng, Piero Vallania, Xu Wang, Q. Y. Yang, S. S. Zhang, J. W. Zhao, R. Santonico, Hongbo Hu, G. Zizzi, A. Surdo, C. F. Feng, M. Iacovacci, P. Creti, Paolo Camarri, A. K. Calabrese Melcarne, T. Di Girolamo, F. R. Zhu, B. D'Ettorre Piazzoli, X. J. Bi, S. N. Sbano, R. Cardarelli, S. Z. Chen, Y. H. Tan, X. Zuo, B. k. Zhang, P. Salvini, G. Marsella, Lanqing Ma, Labaciren, Paolo Montini, S. H. Feng, R. Iuppa, L. Xue, M. Zha, S. Vernetto, B. Panico, X. X. Li, L. Zhang, Hong-peng Lu, S. M. Mari, I. Bolognino, S. W. Cui, J. K. K. Liu, B. Z. Dai, I. De Mitri, F. Ruggieri, Zhen Cao, Chang-Chun Ning, Zhaoyang Feng, Y. Zhang, Danzengluobu, A. F. Yuan, T. L. Chen, Bin Zhou, Q. Q. Zhu, Q. B. Gou, Huihai He, Haibing Hu, G. Mancarella, C. Hou, P. Branchini, Ming Chen, H. Y. Jia, B. Bartoli, X. D. Sheng, Y. X. Bai, Paolo Bernardini, Pengnian Shen, S. Catalanotti, G. C. Xiao, D. Martello, L. Perrone, G. Di Sciascio, M. Panareo, X. C. Yang, Y. Q. Guo, C. Y. Wu, Carlo Vigorito, Y. B. Chen, H. J. Li, H. R. Wu, P. Pistilli, H. M. Zhang, Jiali Liu, X. X. Zhou, M. H. Gu, X. Y. Zhang, Minghui Liu, Zhaxisangzhu, Z. G. Yao, X. H. Ma, Zhaxiciren, H. W. Wang, A. Budano, Fudong Shi, S. Mastroianni, G. Liguori, C. X. Liu, B., Bartoli, Bernardini, Paolo, X. J., Bi, I., Bolognino, P., Branchini, A., Budano, A. K., Calabrese Melcarne, P., Camarri, Z., Cao, R., Cardarelli, S., Catalanotti, S. Z., Chen, T. L., Chen, P., Creti, S. W., Cui, B. Z., Dai, D'Amone, Antonio, Danzengluobu, DE MITRI, Ivan, B., D'Ettorre Piazzoli, T., Di Girolamo, G., Di Sciascio, C. F., Feng, Zhaoyang, Feng, Zhenyong, Feng, Q. B., Gou, Y. Q., Guo, H. H., He, Haibing, Hu, Hongbo, Hu, M., Iacovacci, R., Iuppa, H. Y., Jia, Labaciren, H. J., Li, G., Liguori, C., Liu, J., Liu, M. Y., Liu, H., Lu, L. L., Ma, X. H., Ma, Mancarella, Giovanni, S. M., Mari, Marsella, Giovanni, Martello, Daniele, S., Mastroianni, P., Montini, C. C., Ning, Panareo, Marco, B., Panico, Perrone, Lorenzo, P., Pistilli, F., Ruggieri, P., Salvini, R., Santonico, S. N., Sbano, P. R., Shen, X. D., Sheng, F., Shi, A., Surdo, Y. H., Tan, P., Vallania, S., Vernetto, C., Vigorito, H., Wang, C. Y., Wu, H. R., Wu, L., Xue, Q. Y., Yang, X. C., Yang, Z. G., Yao, A. F., Yuan, M., Zha, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhang, J., Zhao, Zhaxiciren, Zhaxisangzhu, X. X., Zhou, F. R., Zhu, Q. Q., Zhu, G., Zizzi, Y. X., Bai, M. J., Chen, Y., Chen, S. H., Feng, B., Gao, M. H., Gu, C., Hou, X. X., Li, J. L., Liu, X., Wang, G., Xiao, B. K., Zhang, S. S., Zhang, B., Zhou, X., Zuo, P., Bernardini, Catalanotti, Sergio, A., D'Amone, I., De Mitri, DI GIROLAMO, Tristano, Q., Huang, Iacovacci, Michele, B. Bartoli, BERNARDINI, Paolo, X. J. Bi, I. Bolognino, P. Branchini, A. Budano, A. K. Calabrese Melcarne, P. Camarri, Z. Cao, R. Cardarelli, S. Catalanotti, S. Z. Chen, T. L. Chen, P. Creti, S. W. Cui, B. Z. Dai, D'AMONE, ANTONIO, B. D'Ettorre Piazzoli, T. Di Girolamo, G. Di Sciascio, C. F. Feng, Zhaoyang Feng, Zhenyong Feng, Q. B. Gou, Y. Q. Guo, H. H. He, Haibing Hu, Hongbo Hu, M. Iacovacci, R. Iuppa, H. Y. Jia, H. J. Li, G. Liguori, C. Liu, J. Liu, M. Y. Liu, H. Lu, L. L. Ma, X. H. Ma, MANCARELLA, Giovanni, S. M. Mari, MARSELLA, GIOVANNI, MARTELLO, Daniele, S. Mastroianni, P. Montini, C. C. Ning, PANAREO, Marco, B. Panico, PERRONE, Lorenzo, P. Pistilli, F. Ruggieri, P. Salvini, R. Santonico, S. N. Sbano, P. R. Shen, X. D. Sheng, F. Shi, A. Surdo, Y. H. Tan, P. Vallania, S. Vernetto, C. Vigorito, H. Wang, C. Y. Wu, H. R. Wu, L. Xue, Q. Y. Yang, X. C. Yang, Z. G. Yao, A. F. Yuan, M. Zha, H. M. Zhang, L. Zhang, X. Y. Zhang, Y. Zhang, J. Zhao, X. X. Zhou, F. R. Zhu, Q. Q. Zhu, G. Zizzi, Y. X. Bai, M. J. Chen, Y. Chen, S. H. Feng, B. Gao, M. H. Gu, C. Hou, X. X. Li, J. L. Liu, X. Wang, G. Xiao, B. K. Zhang, S. S. Zhang, B. Zhou, and X. Zuo

Subjects
Nuclear and High Energy Physics, Hydrogen, Astrophysics::High Energy Astrophysical Phenomena, ARGO-YBJ, FOS: Physical sciences, chemistry.chemical_element, Cosmic ray, High Energy Physics - Experiment, law.invention, Nuclear physics, Telescope, High Energy Physics - Experiment (hep-ex), law, Instrumentation, Cherenkov radiation, Helium, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Range (particle radiation), COSMIC cancer database, Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, Hybrid measurement, Astronomy and Astrophysics, Alpha particle, chemistry, Cherenkov telescope, Energy Spectrum, Astrophysics - High Energy Astrophysical Phenomena, Composition
Abstract

The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured, below the so-called "knee", by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive Plate Chamber (RPC) array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range (100 TeV - 700 TeV). The observed energy spectrum is compatible with a single power law with index gamma=-2.63+/-0.06., Comment: To be published on Chinese Physics C

Published
2014

50. Geometry and optics calibration of WFCTA prototype telescopes using star light

Author

Y. Zhang, Zhen Cao, S. S. Zhang, Xiao-Xiao Li, Li-Hong Chen, M. Zha, Kai-Qi Ding, Xiangdong Sheng, Lingling Ma, Jiali Liu, Xinhua Ma, Jia Liu, Ming-Jun Chen, G. C. Xiao, Yao Chen, Jing Zhao, Huihai He, Bin Zhou, Y. X. Bai, and S. Z. Chen

Subjects
Physics, Nuclear and High Energy Physics, High energy, Physics - Instrumentation and Detectors, business.industry, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Gamma-ray astronomy, Instrumentation and Detectors (physics.ins-det), Star (graph theory), Cherenkov Telescope Array, Air shower, Optics, Observatory, Calibration, business, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract

The Large High Altitude Air Shower Observatory project is proposed to study high energy gamma ray astronomy ( 40 GeV-1 PeV ) and cosmic ray physics ( 20 TeV-1 EeV ). The wide field of view Cherenkov telescope array, as a component of the LHAASO project, will be used to study energy spectrum and compositions of cosmic ray by measuring the total Cherenkov light generated by air showers and shower maximum depth. Two prototype telescopes have been in operation since 2008. The pointing accuracy of each telescope is crucial to the direction reconstruction of the primary particles. On the other hand the primary energy reconstruction relies on the shape of the Cherenkov image on the camera and the unrecorded photons due to the imperfect connections between photomultiplier tubes. UV bright stars are used as point-like objects to calibrate the pointing and to study the optical properties of the camera, the spot size and the fractions of unrecorded photons in the insensitive areas of the camera., 5 pages, 6 figures, submitted to Chinese Physics C

Published
2010

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