The design and performance of GRD onboard the GECAM satellite

An, Zhongfu; Sun, Xilei; Zhang, D. L.; Yang, S.; Li, X. Q.; Gong, Ke; Liang, X. H.; Liu, Xiangjun; Liu, Y. Q.; Li, Y. G.; Xiong, S. L.; Xu, Y. B.; Zhang, Fan; Zhao, X. Y.; Chang, Zhe; Chen, G.; Chen, C.; Du, Y. Y.; Feng, Ping; Gao, Min; Gao, Ruihong; Guo, D. Y.; He, J.; Hou, Dongjie; Li, C. Y.; Li, G.; Li, X. F.; Li, M. S.; Lu, H.; Meng, Bin; Peng, W. X.; Shi, Feng; Wang, H.; Wang, J. Z.; Wang, Y. S.; Wang, H. Z.; Wen, Xiang-Yang; Xiao, Shuo; Xu, Yupeng; Yang, Jiajia; Yi, Q. B.; Zhang, S. N.; Zhang, C. Y.; Zhang, C. M.; Zhang, Fei; Zhao, Y.; Zhou, Xiaolong

doi:10.1007/s41605-021-00289-y

Cited by 17 publications

(8 citation statements)

References 14 publications

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“…Each GECAM spacecraft has an all-sky field of view unblocked by the Earth, capable of triggering bursts in real-time 47 and distributing trigger alerts promptly with the Global Short Message Communication of Beidou satellite navigation system 48 . As the main instrument of GECAM, most gamma-ray detectors (GRDs) operate in two readout channels: high gain (HG) and low gain (LG), which are independent in terms of data processing, transmission, and dead-time 49 . Comprehensive ground and cross calibrations have been conducted on the GRDs of both GECAM-B and GECAM-C 17, 50-52 .…”

Section: Data Reductionmentioning

confidence: 99%

Magnetar emergence in a peculiar gamma-ray burst from a compact star merger

Zhang

Sun

Wang

et al. 2023

Preprint

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The central engine that powers gamma-ray bursts (GRBs), the most powerful explosions in the universe, is still not identified. Besides hyper-accreting black holes, rapidly spinning and highly magnetized neutron stars, known as millisecond magnetars, have been suggested to power both long and short GRBs1–7. The presence of a magnetar engine following compact star mergers is of particular interest as it would provide essential constraints on the poorly understood equation of state for neutron stars8, 9. Indirect indications of a magnetar engine in these merger sources have been observed in the form of plateau features present in the X-ray afterglow light curves of some short GRBs10, 11. Additionally, some X-ray transients lacking gamma-ray bursts (GRB-less) have been identified as potential magnetar candidates originating from compact star mergers6, 12, 13. Nevertheless, smoking gun evidence is still lacking for a magnetar engine in short GRBs, and the associated theoretical challenges have been addressed14. Here we present a comprehensive analysis of the broad-band prompt emission data of a peculiar, very bright GRB 230307A. Despite its apparently long duration, the prompt emission and host galaxy properties point toward a compact star merger origin, being consistent with its association with a kilonova15. More intriguingly, an extended X-ray emission component emerges as the γ-ray emission dies out, signifying the emergence of a magnetar central engine. We also identify an achromatic temporal break in the high-energy band during the prompt emission phase, which was never observed in previous bursts and reveals a narrow jet with half opening angle of approximately 3.4◦.

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Section: Data Reductionmentioning

confidence: 99%

Magnetar emergence in a peculiar gamma-ray burst from a compact star merger

Zhang

Sun

Wang

et al. 2023

Preprint

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“…The GECAM payload mainly consists of 25 GRDs (for 15 keV-5 MeV X/γ rays), eight CPDs (for 150 keV-5 MeV charged particles), and the Electronic Box (EBOX, An et al 2022;Li et al 2022b;Xu et al 2022). As illustrated in Figure 1, 25 GRDs and six CPDs are placed with different orientations in the detector dome of the GECAM satellite to monitor most of the sky region, while two CPDs are installed on the +X side of the payload EBOX.…”

Section: The Gecam Instrumentmentioning

confidence: 99%

“…For simplicity, only the counts from ∼30 keV to ∼200 keV (i.e., PI channels from 45 to 150) of the high-gain channel are adopted in the localization of the present work, because most counts from detected bursts are recorded in this energy range. The detector response is constructed based on a series of ground tests (Zhang et al 2019;An et al 2022;Li et al 2022b) before launch and comprehensive simulations incorporating the GECAM spacecraft mass model into GEANT4 (Guo et al 2020), and has been further calibrated in-flight with characteristic lines and known bursts (Zhang et al 2022c;Zheng et al 2022;R. Qiao et al 2023, in preparation;Y.…”

Section: The Gecam Instrumentmentioning

confidence: 99%

“…Launched in 2020 December, GECAM has been operating in low Earth orbit (600 km altitude and 29°inclination angle, Han et al 2020). GECAM consists of twin microsatellites (i.e., GECAM-A and GECAM-B) and each comprises 25 gammaray detectors (GRDs, Lv et al 2018;Zhang et al 2019;An et al 2022) and eight charged particle detectors (CPDs, Li et al 2022a;Xu et al 2022;Zhang et al 2022a). With the LaBr 3 crystal read out by a silicon photomultiplier array, GRDs could monitor the entire unocculted sky in the energy range of ∼15 keV to ∼5 MeV (Zhang et al 2022b(Zhang et al , 2022d.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

GECAM Localization of High-energy Transients and the Systematic Error

Zhao

Xue

Xiong³

et al. 2023

ApJS

Self Cite

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The Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a pair of microsatellites (i.e., GECAM-A and GECAM-B) dedicated to monitoring gamma-ray transients including the high-energy electromagnetic counterparts of gravitational waves, such as gamma-ray bursts, soft gamma-ray repeaters, solar flares, and terrestrial gamma-ray flashes. Since launch in 2020 December, GECAM-B has detected hundreds of astronomical and terrestrial events. For these bursts, localization is the key for burst identification and classification as well as follow-up observations in multiple wavelengths. Here, we propose a Bayesian localization method with Poisson data with Gaussian background profile likelihood to localize GECAM bursts based on the distribution of burst counts in detectors with different orientations. We demonstrate that this method can work well for all kinds of bursts, especially extremely short ones. In addition, we propose a new method to estimate the systematic error of localization based on a confidence level test, which can overcome some problems of the existing method in the literature. We validate this method by Monte Carlo simulations, and then apply it to a burst sample with accurate location and find that the mean value of the systematic error of GECAM-B localization is ∼2.°5. By considering this systematic error, we can obtain a reliable localization probability map for GECAM bursts. Our methods can be applied to other gamma-ray monitors.

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“…These two domes are installed on the top and bottom of SATech-01 satellite. There are six gamma-ray detectors (GRDs) [4] and one charge particle detector (CPD) [5] on each dome, therefore, GECAM-C has a total of 12 GRDs and two CPDs, as shown in Fig 1.…”

Section: Introductionmentioning

confidence: 99%

Dedicated SiPM array for GRD of GECAM

Zhang¹,

Sun

An³

et al. 2022

Radiat Detect Technol Methods

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The gamma-ray detectors (GRDs) of GECAM-C onborad SATech-01 satellite is designed to monitor gamma-ray transients all over the sky from 6 keV to 6 MeV. The energy response matrix is the key to do spectral measurements of bursts, which is usually generated from GEANT4 simulation and partially verified by the ground calibration. In this work, energy response matrix of GECAM-C GRD is cross-calibrated with Fermi/GBM and Swift/BAT using a sample of Gamma-Ray Bursts (GRBs) and Soft Gamma-Ray Repeaters (SGRs). The calibration results show there is a good agreement between GECAM-C and other reasonably well calibrated instrument (i.e. Fermi/GBM and Swift/BAT). We also find that different GRD detectors of GECAM-C also show consistency with each other. All these results indicate that GECAM-C GRD can provide reliable spectral measurements.

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The design and performance of GRD onboard the GECAM satellite

Cited by 17 publications

References 14 publications

Magnetar emergence in a peculiar gamma-ray burst from a compact star merger

Magnetar emergence in a peculiar gamma-ray burst from a compact star merger

GECAM Localization of High-energy Transients and the Systematic Error

Dedicated SiPM array for GRD of GECAM

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