分类： 天文学 >> 天文学 提交时间： 2023-02-19
Xiao-Yun Zhao
Shao-Lin Xiong
Xiang-Yang Wen
Xin-Qiao Li
Ce Cai
Shuo Xiao
Qi Luo
Wen-Xi Peng
Dong-Ya Guo
Zheng-Hua An
Ke Gong
Jin-Yuan Liao
Yan-Qiu Zhang
Yue Huang
Lu Li
Xing Wen
Fei Zhang
Jing Duan
Chen-Wei Wang
Dong-Li Shi
摘要： Realtime trigger and localization of bursts are the key functions of GECAM, which is an all-sky gamma-ray monitor launched in Dec 10, 2020. We developed a multifunctional trigger and localization software operating on the CPU of the GECAM electronic box (EBOX). This onboard software has the following features: high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation, dedicated localization algorithm optimized for short and long bursts respetively, short time latency of the trigger information which is downlinked throught the BeiDou satellite navigation System (BDS). This paper presents the detailed design and deveopment of this trigger and localization software system of GECAM, including the main functions, general design, workflow and algorithms, as well as the verification and demonstration of this software, including the on-ground trigger tests with simulated gamma-ray bursts made by a dedicated X-ray tube and the in-flight performance to real gamma-ray bursts and magnetar bursts.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Guang-Wei Li
Chao Wu
Gui-Ping Zhou
Chen Yang
Hua-Li Li
Jie Chen
Li-Ping Xin
Jing Wang
Hasitieer Haerken
Chao-Hong Ma
Hong-Bo Cai
Xu-Hui Han
Lei Huang
Xiao-Meng Lu
Jian-Ying Bai
Xu-Kang Zhang
Xin-Li Hao
Xiang-Yu Wang
Zi-Gao Dai
En-Wei Liang
摘要： In the archive of the Ground Wide Angle Camera (GWAC), we found 43 white light flares from 43 stars, among which, three are sympathetic or homologous flares, and one of them also has a quasi-periodic pulsation with a period of $13.0\pm1.5$ minutes. Among these 43 flare stars, there are 19 new active stars and 41 stars that have available TESS and/or K2 light curves, from which we found 931 stellar flares. We also obtained rotational or orbital periods of 34 GWAC flare stars, of which 33 are less than 5.4 days, and ephemerides of three eclipsing binaries from these light curves. Combining with low resolution spectra from LAMOST and the Xinglong 2.16m telescope, we found that $L_{\rm H\alpha}/L_{\rm bol}$ are in the saturation region in the rotation-activity diagram. From the LAMOST medium-resolution spectrum, we found that Star \#3 (HAT 178-02667) has double H$\alpha$ emissions which imply it is a binary, and two components are both active stars. Thirteen stars have flare frequency distributions (FFDs) from TESS and/or K2 light curves. These FFDs show that the flares detected by GWAC can occur at a frequency of 0.5 to 9.5 yr$^{-1}$. The impact of flares on habitable planets was also studied based on these FFDs, and flares from some GWAC flare stars may produce enough energetic flares to destroy ozone layers, but none can trigger prebiotic chemistry on their habitable planets.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Guang-Wei Li
Chao Wu
Gui-Ping Zhou
Chen Yang
Hua-Li Li
Jie Chen
Li-Ping Xin
Jing Wang
Hasitieer Haerken
Chao-Hong Ma
Hong-Bo Cai
Xu-Hui Han
Lei Huang
Xiao-Meng Lu
Jian-Ying Bai
Xu-Kang Zhang
Xin-Li Hao
Xiang-Yu Wang
Zi-Gao Dai
En-Wei Liang
摘要： In the archive of the Ground Wide Angle Camera (GWAC), we found 43 white light flares from 43 stars, among which, three are sympathetic or homologous flares, and one of them also has a quasi-periodic pulsation with a period of $13.0\pm1.5$ minutes. Among these 43 flare stars, there are 19 new active stars and 41 stars that have available TESS and/or K2 light curves, from which we found 931 stellar flares. We also obtained rotational or orbital periods of 34 GWAC flare stars, of which 33 are less than 5.4 days, and ephemerides of three eclipsing binaries from these light curves. Combining with low resolution spectra from LAMOST and the Xinglong 2.16m telescope, we found that $L_{\rm H\alpha}/L_{\rm bol}$ are in the saturation region in the rotation-activity diagram. From the LAMOST medium-resolution spectrum, we found that Star \#3 (HAT 178-02667) has double H$\alpha$ emissions which imply it is a binary, and two components are both active stars. Thirteen stars have flare frequency distributions (FFDs) from TESS and/or K2 light curves. These FFDs show that the flares detected by GWAC can occur at a frequency of 0.5 to 9.5 yr$^{-1}$. The impact of flares on habitable planets was also studied based on these FFDs, and flares from some GWAC flare stars may produce enough energetic flares to destroy ozone layers, but none can trigger prebiotic chemistry on their habitable planets.
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