{"paper":{"title":"EP241021a: a months-duration X-ray transient with luminous optical and radio emission","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"Aguado David S., Andrews Moira, An Fangxia, An Jie, An Tao, Anutarawiramkul Rungrit, Baldini Pietro, Brink Thomas G., Butpa Pathompong, Cai Zhiming, Castro-Tirado Alberto J., Cheng Huaqing, Chen Jinhong, Cui WeiWei, Dai Lixin, Ding Hucheng, Eyles-Ferris Rob A. J., Farah Joseph, Fern\\'andez-Nespral David L\\'opez, Filippenko Alexei V., Fu Shaoyu, Gao Xing, Han DaWei, Han Xuhui, Howell D. Andrew, Hu Jingwei, Jiang Ning, Jiang Shuaiqing, Jin Chichuan, Johan P.U. Fynbo, Kumar Amit, Lei WeiHua, Li ChengKui, Li Dongyue, Liu Huaqiu, Liu Xing, Liu Yuan, Li Wenxiong, L\\'opez-Oramas Alicia, Maund Justyn R., McCully Curtis, Nandra Kirpal, Newsome Megan, Niu Zexi, Padilla Gonzalez Estefania, Pan Haiwu, Paul O'Brien, P\\'erez-Fournon Ismael, Poidevin Fr\\'ed\\'erick, Rau Arne, Shen Rongfeng, Shu Xinwen, Silim Walter, Soria Roberto, Sun Hui, Sun Luming, Sun Ningchen, Sun Shengli, Sun Xiaojin, Terreran Giacomo, Tinyanont Samaporn, Wang Junxian, Wang Tinggui, Wang Yanan, Wang Yun, Wiersema Klass, Wu Xuefeng, Xu Dong, Xue Yongquan, Xu Fan, Xu Yunfei, Yang Haonan, Yang Lei, Yuan Weimin, Yu Yunwei, Zhang Bing, Zhang Fabao, Zhang Juan, Zhang Pinpin, Zhang Wenda, Zhang Yonghe, Zhang Zhumao, Zhao Haisheng, Zheng Weikang, Zhu Zipei","submitted_at":"2025-05-12T15:31:21Z","abstract_excerpt":"We present the discovery of a peculiar X-ray transient, EP241021a, by the Einstein Probe (EP) mission, and the results from multiwavelength follow-up observations. The transient was first detected with the Wide-field X-ray Telescope as an intense flare lasting for ~100 s, reaching a luminosity of L_(0.5-4 keV)~10^48 erg/s at z=0.748. Further observations with EP's Follow-up X-ray Telescope reveal a huge drop in the X-ray flux by a factor of >1000 within 1.5 days. After maintaining a nearly plateau phase for ~7 days, the X-ray flux declines as t^-1.2 over a period of ~30 days, followed by a sud"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2505.07665","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2505.07665/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}