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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. 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

3. 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

4. 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

5. 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

6. 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

7. 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
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8. 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

9. 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
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10. 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

11. 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

12. 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
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13. 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

14. 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
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15. 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

16. 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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