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Effects of Binary Interactions on the Early-type Galaxy Chemical evolution and Gas Cooling Functiontwo

Chinese Astronomy and Astrophysics 2018年第4期42卷 527-537页

作者： Lang, Wang Yunnan Astronomical Observatories Chinese Academy of Sciences Kunming 650011 China University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing 100012 China

In the galaxy parameter fitting by means of stellar population synthesis, it is found that compared with the evolutionary population synthesis (EPS) model without binary interactions, the stellar age and metallicity of a galaxy derived from the EPS model with binary interactions are larger. But, we are still unclear how the binary interactions affect the galaxy evolution. For the early-type galaxies with the UV-excess phenomenon, there are two main-stream explanations: recent star formation (RSF) and binary interactions. In this study, we obtain the mass return rate and chemical yield for the stellar populations with and without binary interactions. In combination with the galaxy chemical evolution and photoionization models, we study the effects of binary interactions on the chemical evolution and metallicity evolution for the early-type galaxies with the UV-excess phenomenon under the two formation mechanisms. We find that the inclusion of binary interactions can raise the ejected mass, metallicity, alpha element, and accelerate the gas cooling. These can reasonably explain the conclusions made by the EPS models. Moreover, we find that the gas cooling is more efficient under the UV-excess formation mechanism by the binary interactions rather than the RSF, and the ratio of element abundance is different for the two mechanisms, which can be further used to distinguish these two mechanisms. © 2018

关键词： Abundances—galaxies evolution Galaxies ISM—galaxies

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evolution of Dipolar Mixed-mode Coupling Factor in Red Giant Stars: Impact of Buoyancy Spike

arXiv

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arXiv 2022年

作者： Jiang, Chen Cunha, Margarida Christensen-Dalsgaard, Joergen Zhang, Qiansheng S. Gizon, Laurent Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3 Göttingen37077 Germany Instituto de Astrofísica e Ciências do Espaço Universidade do Porto CAUP Rua das Estrelas Porto4150-762 Portugal Stellar Astrophysics Centre Department of Physics and Astronomy Aarhus University Ny Munkegade 120 Aarhus CDK-8000 Denmark Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Institut für Astrophysik Georg-August-Universität Göttingen Friedrich-Hund-Platz 1 Göttingen37077 Germany Center for Space Science NYUAD Institute New York University Abu Dhabi Abu Dhabi United Arab Emirates

Mixed modes observed in red giants allow for investigation of the stellar interior structures. One important feature in these structures is the buoyancy spike caused by the discontinuity of the chemical gradient left behind during the first dredge-up. The buoyancy spike emerges at the base of the convective zone in low-luminosity red giants and later becomes a glitch when the g-mode cavity expands to encompass the spike. Here, we study the impact of the buoyancy spike on the dipolar mixed modes using stellar models with different properties. We find that the applicability of the asymptotic formalisms for the coupling factor, q, varies depending on the location of the evanescent zone, relative to the position of the spike. Significant deviations between the value of q inferred from fitting the oscillation frequencies and either of the formalisms proposed in the literature are found in models with a large frequency separation in the interval 5 to 15 µHz, with evanescent zones located in a transition region which may be thin or thick. However, it is still possible to reconcile q with the predictions from the asymptotic formalisms, by choosing which formalism to use according to the value of q. For stars approaching the luminosity bump, the buoyancy spike becomes a glitch and strongly affects the mode frequencies. Fitting the frequencies without accounting for the glitch leads to unphysical variations in the inferred q, but we show that this is corrected when properly accounting for the glitch in the fitting. Copyright © 2022, The Authors. All rights reserved.

关键词： Buoyancy

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Optical Continuum Reverberation Mapping of a Candidate IMBH in a Nearby Seyfert 1 Galaxy

arXiv

引用

arXiv 2024年

作者： Zuo, Wenwen Guo, Hengxiao Sun, Jingbo Yuan, Qi Lira, Paulina Gu, Minfeng Edwards, Philip G. Gupta, Alok C. Kishore, Shubham Stevens, Jamie An, Tao Cai, Zhen-Yi Feng, Hai-Cheng Ho, Luis C. Ilić, Dragana Kovačević, Andjelka B. Li, Sha-Sha Mezcua, Mar Popović, Luka Č. Sun, Mouyuan Tripathi, Tushar Vivian, U. Vince, Oliver Wang, Jianguo Wang, Junxian Wang, Shu Wu, Xuebing Zheng, Zhenya Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China Changchun Observatory National Astronomical Observatories Chinese Academy of Sciences West Hill of Jingyue Lake Changchun130117 China Departamento de Astronom Universidad de Chile Casilla Santiago Chile36D Chile CSIRO Astronomy and Space Science PO Box 76 EppingNSW1710 Australia Manora Peak Nainital263001 India Department of Physics DDU Gorakhpur University Gorakhpur273009 India CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Anhui Hefei230026 China School of Astronomy and Space Science University of Science and Technology of China Hefei230026 China Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Yunnan Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Yunnan Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy School of Physics Peking University Beijing100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China University of Belgrade Faculty of Mathematics Department of Astronomy Studentski trg 16 Belgrade Serbia Hamburger Sternwarte Universitat Hamburg Gojenbergsweg 112 HamburgD-21029 Germany Campus UAB Carrer de Magrans Barcelona08193 Spain Edifici RDIT Campus UPC Castelldefels Barcelona08860 Spain Astronomical Observatory Volgina 7 Belgrade11060 Serbia Department of Astronomy Xiamen University Fujian Xiamen361005 China Department of Physics and Astronomy University of California 4129 Frederick Reines Hall IrvineCA92697-4575 United States Department of Physics & Astronomy Seoul National University Seoul08826

To investigate the short-term variability and determine the size of the optical continuum emitting region of intermediate-mass black holes (IMBHs), we carried out high-cadence, multiband photometric monitoring of a Seyfert 1 galaxy J0249−0815 across two nights, together with a one-night single-band preliminary test. The presence of the broad Hα component in our target was confirmed by recent Palomar/P200 spectroscopic observations, 23 yr after the Sloan Digital Sky Survey, ruling out the supernovae origin of the broad Hα line. The photometric experiment was primarily conducted utilizing four-channel imagers MuSCAT 3 and 4 mounted on 2 m telescopes within the Las Cumbres Observatory Global Telescope Network. Despite the expectation of variability, we observed no significant variation ( Copyright © 2024, The Authors. All rights reserved.

关键词： Reverberation

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Hot subdwarf stars observed in Gaia DR2 and LAMOST DR5

arXiv

引用

arXiv 2019年

作者： Luo, Yangping Németh, Péter Deng, Licai Han, Zhanwen Department of Astronomy China West Normal University Nanchong637002 China Astronomical Institute Czech Academy of Sciences CZ-25 165 Ondrejov Czech Republic *** Malomsok8533 Hungary Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

Combing Gaia DR2 with LAMOST DR5, we spectroscopically identified 924 hot subdwarf stars, among which 32 stars exhibit strong double-lined composite spectra. We measured the effective temperature Teff, surface gravity log g, helium abundance y = nHe/nH, and radial velocities of 892 non-composite spectra hot subdwarf stars by fitting LAMOST observations with Tlusty/Synspec non-LTE synthetic spectra. We outlined four different groups in the Teff − log g diagram with our helium abundance classification scheme and two nearly parallel sequences in the Teff −log(y) diagram. 3D Galactic space motions and orbits of 747 hot subdwarf stars with (GBP − GRP)0 z−eccentricity diagram, and Galactic orbits, we derived Galactic population classifications and the fractional distributions of the four hot subdwarf helium groups in the halo, thin disk and thick disk. Comparisons with the predictions of binary population synthesis calculations (Han 2008) suggest that He-rich hot subdwarf stars with log(y) ≥ 0 are from the double helium white dwarfs merger, He-deficient hot subdwarf stars with −2.2 ≤ log(y) Copyright © 2019, The Authors. All rights reserved.

关键词： White dwarfs

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Evolving neutron star+helium star systems to intermediate-mass binary pulsars

arXiv

引用

arXiv 2019年

作者： Tang, W. Liu, D. Wang, B. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China

Intermediate-mass binary pulsars (IMBPs) are composed of neutron stars (NSs) and CO/ONe white dwarfs (WDs). It is generally suggested that IMBPs evolve from intermediate-mass X-ray binaries (IMXBs). However, this scenario is difficult to explain the formation of IMBPs with orbital periods (Porb) less than 3 d. It has recently been proposed that a system consisting of a neutron star (NS) and a helium (He) star can form IMBPs with Porbless than 3 d (known as the NS+He star scenario), but previous works can only cover a few observed sources with short orbital periods. We aim to investigate the NS+He star scenario by adopting different descriptions of the Eddington accretion rate ( MEdd) for NSs and different NS masses (MNS) varying from 1.10Moto 1.80Mo. Our results can cover most of the observed IMBPs with short orbital periods and almost half of the observed IMBPs with long orbital periods. We found that MEdd∝MNS-1/3could match the observations better than a specific value for all NSs. We also found that the final spin periods of NSs slightly decrease with the initial MNS. The observed parameters of PSR J0621+1002, which is one of the well-observed IMBPs whose pulsar mass has been precisely measured, can be reproduced by the present work. Copyright © 2019, The Authors. All rights reserved.

关键词： White dwarfs

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Detection of an Orphan X-ray Flare from a Blazar Candidate EP240709a with Einstein Probe

arXiv

引用

arXiv 2024年

作者： Liu, Mingjun Zhang, Yijia Wang, Yun Xue, Rui Buckley, David Howell, D. Andrew Jin, Chichuan Li, Wenxiong Monageng, Itumeleng Pan, Haiwu Sun, Ning-Chen Tinyanont, Samaporn Wang, Lingzhi Yuan, Weimin An, Jie Andrews, Moira Anutarawiramkul, Rungrit Butpan, Pathompong Cheng, Huaqing Dai, Cui-Yuan Dai, Lixin Farah, Joseph Feng, Hua Fu, Shaoyu Guo, Zhen Jiang, Shuaiqing Li, An Li, Dongyue Liang, Yifang Liu, Heyang Liu, Xing Liu, Yuan Mao, Jirong McCully, Curtis Newsome, Megan Gonzalez, Estefania Padilla Pan, Xin Sun, Xinxiang Terreran, Giacomo Wang, Ze-Rui Wu, Qinyu Xiao, Hubing Xiong, Dingrong Xu, Dong Xu, Xinpeng Xue, Suijian Yang, Haonan Yang, Jun Zhang, Jin Zhang, Wenda Zhang, Wenjie Zou, Hu National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China Department of Astronomy Tsinghua University Beijing100084 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210034 China Department of Physics Zhejiang Normal University Jinhua321004 China South African Astronomical Observatory Cape Town7935 South Africa Department of Astronomy University of Cape Town Rondebosch7701 South Africa Department of Physics University of the Free State Bloemfontein9300 South Africa Las Cumbres Observatory 6740 Cortona Drive Suite 102 GoletaCA93117-5575 United States Department of Physics University of California Santa BarbaraCA93106-9530 United States Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China National Astronomical Research Institute of Thailand 260 Moo 4 Donkaew Maerim Chiang Mai50180 Thailand National Astronomical Observatories Chinese Academy of Sciences Beijing China CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing China School of Astronomy and Space Science Nanjing University Nanjing210023 China Key Laboratory of Modern Astronomy and Astrophysics Nanjing University Ministry of Education Nanjing210023 China Department of Physics University of Hong Kong Pokfulam Road Hong Kong Las Cumbres Observatory 6740 Cortona Drive Suite 102 GoletaCA93117-557 United States Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Instituto de Física y Astronomía Universidad de Valparaíso ave. Gran Bretaña 1111 Casilla 5030 Valparaíso Chile Millennium Institute of Astrophysics Nuncio Monseñor Sotero Sanz 100 Of. 104 Providencia Santiago Chile

Blazars are often observed to flare across multiple wavelengths. Orphan flares from blazars have been only detected a few times, providing an opportunity to understand the structure of the jet in the accreting system. We report a remarkable orphan X-ray flare from a blazar candidate EP240709a, detected by Einstein Probe (EP) in July 2024. The multi-band spectral properties and variability support EP240709a as a high-energy peaked BL Lacertae-type object. The flux in 0.5-10 keV increases by at least 28 times to the value of low state in 2020, with non-detection of remarkable flaring in other bands during the same period. EP240709a exhibits the harder-when-brighter tendency in the X-ray band during the orphan flare, while its infrared-optical spectra are featureless. We employ one-zone and two-zone leptonic synchrotron self-Compton models to perform the spectral energy distribution fitting. Detecting this rare orphan flare shows the potential of EP in discovering peculiar activities from AGN in high-cadence X-ray sky surveys. © 2024, CC BY.

关键词： Probes

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Using the Extragalactic Gamma-Ray Background to Constrain the Hubble Constant and Matter Density of the Universe

arXiv

引用

arXiv 2019年

作者： Zeng, Houdun Yan, Dahai Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China

The attenuation produced by extragalactic background light (EBL) in γ-ray spectra of blazars has been used to constrain the Hubble constant (H0) and matter density (Ωm) of the Universe. We propose to estimate H0 and Ωm using the well measured >10 GeV extragalactic γ-ray background (EGB). This suggestion is based on the facts that the >10 GeV EGB is totally explained by the emissions from blazars, and an EBL-absorption cutoff occurs at ∼50 GeV in the EGB spectrum. We fit the >10 GeV EGB data with modeled EGB spectrum. This results in H0 = 64.9+4−4..63 km s−1 Mpc−1 and Ωm = 0.31−+00..1314. Note that the uncertainties may be underestimated due to the limit of our realization for EBL model. H0 and Ωm are degenerate in our method. Independent determination of Ωm by other methods would improve the constraint on H0. Copyright © 2019, The Authors. All rights reserved.

关键词： Gamma rays

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Simulating kilonovae in the ΛCDM universe

arXiv

引用

arXiv 2020年

作者： Jiang, Zhen Wang, Jie Zhang, Fenghui Li, Li-Xin Wang, Lan Li, Ran Gao, Liang Han, Zhanwen Pan, Jun Key Laboratory for Computational Astrophysics National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100049 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Institute of Computational Cosmology Department of Physics University of Durham South Road DurhamDH1 3LE United Kingdom

Kilonovae are optical flashes produced in the aftermath of neutron star-neutron star mergers (NNMs) or neutron star-black hole mergers (NBMs). The multi-messager observation of the recent gravitational wave event GW170817 confirms that it originated from a NNM and triggered a kilonova. In this work, we use the Millennium Simulation, combined with a semi-analytic galaxy formation model-GABE (Galaxy Assembly with Binary evolution) which adopts binary stellar population synthesis models, to explore the cosmic event rate of kilonovae, and the properties of their host galaxies in a cosmological context. We find that model with supernova kick velocity of Vkick = 0 km s−1 fits the observation best, in agreement with the exception of some formation channels of binary neutron star. This indicates that NNMs prefer to originate from binary systems with low kick velocities. With Vkick = 0 km s−1, the cosmic event rate of NNMs and NBMs at z = 0 are 283 Gpc−3 yr−1 and 91 Gpc−3 yr−1, respectively, marginally consistent with the constraint from LVC GWTC-1. For Milky Way-mass galaxies, we predict the NNM rate is 25.7−+759.1.6 Myr−1, which is also in good agreement with the observed properties of binary neutron stars in the Milky Way. Taking all the NNMs into account in the history of Milky Way-mass galaxies, we find that the averaged r-process elements yield with A > 79 in a NNM and NBM event should be 0.01 M☉ to be consistent with observation. We conclude that NGC 4993, the host galaxy of GW170817, is a typical host galaxy for NNMs. However, generally NNMs and NBMs tend to reside in young, blue, star-forming, late-type galaxies, with stellar mass and gaseous metallicity distribution peaking at M∗ = 1010.65 M☉ and 12 + log (O/H) = 8.72 − 8.85, respectively. By studying kilonovae host galaxies in the cosmological background, it is promising to constrain model details better when we have more events in the forthcoming future. Copyright © 2020, The Authors. All rights reserved.

关键词： Nucleosynthesis

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Particle accleration and synchrotron self-compton emission in blazar jets I: An application to the quiescent emission

arXiv

引用

arXiv 2019年

作者： Zheng, Y.G. Kang, S.J. Yang, C.Y. Bai, J.M. Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Department of Physics Yunnan Normal University Kunming650092 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial EnvironmentShandong University Weihai264209 China School of Electrical Engineering Liupanshui Normal University Liupanshui Guizhou553004 China

There are still some important unanswered questions about the detailed particle acceleration and escape occurring during the quiescent epoches. As a result, the particle distribution that is adopted in the blazar quiescent spectral model have numerous unconstrained shapes. To help remedy this problem, we introduce a analytical particle transport model to reproduce quiescent broadband spectral energy distribution of blazar. In this model, the exact electron distribution is solved from a generalized transport equation that contains the terms describing first-order and secondary-order Fermi acceleration, escape of particle due to both the advection and spatial diffusion, energy losses due to synchrotron emission and inverse-Compton scattering of an assumed soft photon field. We suggest that the advection is a significant escape mechanism in blazar jet. We find that in our model the advection process tends to harden the particle distribution, which enhances the high energy components of resulting synchrotron and synchrotron self-Comptom spectrum from jet. Our model is able to roughly reproduce the observed spectra of extreme BL Lac object 1ES 0414+009 with reasonable assumptions about the physical parameters. Copyright © 2019, The Authors. All rights reserved.

关键词： Energy dissipation

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Insight-HXMT and GECAM-C observations of the brightest-of-all-time GRB 221009A

arXiv

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arXiv 2023年

作者： An, Zheng-Hua Antier, S. Bi, Xing-Zi Bu, Qing-Cui Cai, Ce Cao, Xue-Lei Camisasca, Anna-Elisa Chang, Zhi Chen, Gang Chen, Li Chen, Tian-Xiang Chen, Wen Chen, Yi-Bao Chen, Yong Chen, Yu-Peng Coughlin, Michael W. Cui, Wei-Wei Dai, Zi-Gao Hussenot-Desenonges, T. Du, Yan-Qi Du, Yuan-Yuan Du, Yun-Fei Fan, Cheng-Cheng Frontera, Filippo Gao, He Gao, Min Ge, Ming-Yu Gong, Ke Gu, Yu-Dong Guan, Ju Guo, Dong-Ya Guo, Zhi-Wei Guidorzi, Cristiano Han, Da-Wei He, Jian-Jian He, Jun-Wang Hou, Dong-Jie Huang, Yue Huo, Jia Ji, Zhen Jia, Shu-Mei Jiang, Wei-Chun Kann, David Alexander Klotz, A. Kong, Ling-Da Lan, Lin Li, An Li, Bing Li, Chao-Yang Li, Cheng-Kui Li, Gang Li, Mao-Shun Li, Ti-Pei Li, Wei Li, Xiao-Bo Li, Xin-Qiao Li, Xu-Fang Li, Yan-Guo Li, Zheng-Wei Liang, Jing Liang, Xiao-Hua Liao, Jin-Yuan Lin, Lin Liu, Cong-Zhan Liu, He-Xin Liu, Hong-Wei Liu, Jia-Cong Liu, Xiao-Jing Liu, Ya-Qing Liu, Yu-Rong Lu, Fang-Jun Lu, Hong Lu, Xue-Feng Luo, Qi Luo, Tao Ma, Bin-Yuan Ma, Fu-Li Ma, Rui-Can Ma, Xiang Maccary, Romain Mao, Ji-Rong Meng, Bin Nie, Jian-Yin Orlandini, Mauro Ou, Ge Peng, Jing-Qiang Peng, Wen-Xi Qiao, Rui Qu, Jin-Lu Ren, Xiao-Qin Shi, Jing-Yan Shi, Qi Song, Li-Ming Song, Xin-Ying Su, Ju Sun, Gong-Xing Sun, Liang Sun, Xi-Lei Tan, Wen-Jun Tan, Ying Tao, Lian Tuo, You-Li Turpin, Damien Wang, Jin-Zhou Wang, Chen Wang, Chen-Wei Wang, Hong-Jun Wang, Hui Wang, Jin Wang, Ling-Jun Wang, Peng-Ju Wang, Ping Wang, Wen-Shuai Wang, Xiang-Yu Wang, Xi-Lu Wang, Yu-Sa Wang, Yue Wen, Xiang-Yang Wu, Bo-Bing Wu, Bai-Yang Wu, Hong Xiao, Sheng-Hui Xiao, Shuo Xiao, Yun-Xiang Xie, Sheng-Lun Xiong, Shao-Lin Xiong, Sen-Lin Xu, Dong Xu, He Xu, Yan-Jun Xu, Yan-Bing Xu, Ying-Chen Xu, Yu-Peng Xue, Wang-Chen Yang, Sheng Yang, Yan-Ji Yang, Zi-Xu Ye, Wen-Tao Yi, Qi-Bin Yi, Shu-Xu Yin, Qian-Qing You, Yuan Yu, Yun-Wei Yu, Wei Yu, Wen-Hui Zeng, Ming Zhang, Bing Zhang, Bin-Bin Zhang, Da-Li Zhang, Fan Zhang, Hong-Mei Zhang, Juan Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences 19B Yuquan Road Beijing100049 China Institut für Astronomie und Astrophysik Kepler Center for Astro and Particle Physics Eberhard Karls Universität Sand 1 Tübingen72076 Germany College of Physics Hebei Key Laboratory of Photophysics Research and Application Hebei Normal University Hebei Shijiazhuang050024 China Department of Physics and Earth Science University of Ferrara Via Saragat 1 Ferrara44122 Italy Department of Astronomy Beijing Normal University Beijing100875 China CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei230026 China Department of Astronomy Tsinghua University Beijing100084 China Southwest Jiaotong University Chengdu610092 China INAF Osservatorio di Astrofisica e Scienza dello Spazio di Bologna Via Piero Gobetti 101 Bologna40129 Italy University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China College of physics Sciences Technology Hebei University No. 180 Wusi Dong Road Lian Chi District Hebei Baoding071002 China INFN - Sezione di Ferrara Via Saragat 1 Ferrara44122 Italy Physics and Space Science College China West Normal University China Yunnan Observatories Chinese Academy of Sciences Yunnan Province Kunming650011 China Key Laboratory of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China School of Astronomy and Space Science Nanjing University Nanjing210093 China School of Physics and Optoelectronics Xiangtan University Yuhu District Hunan Xiangtan411105 China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal University Guiyang550001 China Institute of Astrophysics Central China Normal University Wuhan430079 China Nevada Center for Astrophysics Department of Physics and Astronomy University of

GRB 221009A is the brightest gamma-ray burst ever detected since the discovery of this kind of energetic explosions. However, an accurate measurement of the prompt emission properties of this burst is very challenging due to its exceptional brightness. With joint observations of Insight-HXMT and GECAM-C, we made an unprecedentedly accurate measurement of the emission during the first ∼1800 s of GRB 221009A, including its precursor, main emission (ME, which dominates the burst in flux), flaring emission and early afterglow, in the hard X-ray to soft gamma-ray band from ∼ 10 keV to ∼ 6 MeV. Based on the GECAM-C unsaturated data of the ME, we measure a record-breaking isotropic equivalent energy (Eiso) of ∼ 1.5 × 1055 erg, which is about eight times the total rest-mass energy of the Sun. The early afterglow data require a significant jet break between 650 s and 1100 s, most likely at ∼ 950 s from the afterglow starting time TAG, which corresponds to a jet opening angle of ∼ 0.7◦ (ηγn)1/8, where n is the ambient medium density in units of cm−3 and ηγ is the ratio between γ-ray energy and afterglow kinetic energy. The beaming-corrected total γ-ray energy Eγ is ∼ 1.15 × 1051 (ηγn)1/4 erg, which is typical for long GRBs. These results suggest that this GRB may have a special central engine, which could launch and collimate a very narrowly beamed jet with an ordinary energy budget, leading to exceptionally luminous gamma-ray radiation per unit solid angle. Alternatively, more GRBs might have such a narrow and bright beam, which are missed by an unfavorable viewing angle or have been detected without distance measurement. Copyright © 2023, The Authors. All rights reserved.

关键词： Gamma rays

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