Science objectives of the Einstein Probe mission
Authors: Yuan Weimin , Dai Lixin , Feng Hua , Jin Chichuan , Jonker Peter , Kuulkers Erik , Liu Yuan , Nandra Kirpal , O’Brien Paul , Piro Luigi , Rau Arne , Rea Nanda , Sanders Jeremy , Tao Lian , Wang Junfeng , Wu Xuefeng , Zhang Bing , Zhang Shuangnan , Ai Shunke , Buchner Johannes , Bulbul Esra , Chen Hechao , Chen Minghua , Chen Yong , Chen Yu-Peng , Coleiro Alexis , Zelati Francesco Coti , Dai Zigao , Fan Xilong , Fan Zhou , Friedrich Susanne , Gao He , Ge Chong , Ge Mingyu , Geng Jinjun , Ghirlanda Giancarlo , Gianfagna Giulia , Gou Lijun , Guillot Sébastien , Hou Xian , Hu Jingwei , Huang Yongfeng , Ji Long , Jia Shumei , Komossa S. , Kong Albert K. H. , Lan Lin , Li An , Li Ang , Li Chengkui , Li Dongyue , Li Jian , Li Zhaosheng , Ling Zhixing , Liu Ang , Liu Jinzhong , Liu Liangduan , Liu Zhu , Luo Jiawei , Ma Ruican , Maggi Pierre , Maitra Chandreyee , Marino Alessio , Ng Stephen Chi-Yung , Pan Haiwu , Rukdee Surangkhana , Soria Roberto , Sun Hui , Tam Pak-Hin Thomas , Thakur Aishwarya Linesh , Tian Hui , Troja Eleonora , Wang Wei , Wang Xiangyu , Wang Yanan , Wei Junjie , Wen Sixiang , Wu Jianfeng , Wu Ting , Xiao Di , Xu Dong , Xu Renxin , Xu Yanjun , Xu Yu , Yang Haonan , You Bei , Yu Heng , Yu Yunwei , Zhang Binbin , Zhang Chen , Zhang Guobao , Zhang Liang , Zhang Wenda , Zhang Yu , Zhou Ping , Zou Zecheng 
Published: January 2025

The Einstein Probe (EP) is an interdisciplinary mission of time-domain and X-ray astronomy. Equipped with a wide-field lobster-eye X-ray focusing imager, EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5–4 keV, at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions. EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard. In this paper, the science objectives of the EP mission are presented. EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales. Among them, fast extragalactic transients will be surveyed systematically in soft X-rays, which include γ-ray bursts and their variants, supernova shock breakouts, and the predicted X-ray transients associated with binary neutron star mergers. EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei, possibly at an early phase of the flares for some. EP will monitor the variability and outbursts of X-rays from white dwarfs, neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments, and is expected to discover new objects. A large sample of stellar X-ray flares will also be detected and characterised. In the era of multi-messenger astronomy, EP has the potential of detecting the possible X-ray counterparts of gravitational wave events, neutrino sources, and ultra-high energy γ-ray and cosmic ray sources. EP is expected to help advance the studies of extreme objects and phenomena revealed in the dynamic X-ray universe, and their underlying physical processes. Besides EP’s strength in time-domain science, its follow-up telescope, with excellent performance, will also enable advances in many areas of X-ray astronomy.