A fast powerful X-ray transient from possible tidal disruption of a white dwarf
Abstract
Stars captured by black holes (BHs) can be torn apart by strong tidal forces, producing electromagnetic flares. To date, more than 100 tidal disruption events (TDEs) have been observed, each involving invariably normal gaseous stars whose debris falls onto the BH, sustaining the flares over years. White dwarfs (WDs), which are the most prevalent compact stars and a million times denser--and therefore tougher--than gaseous stars, can only be disrupted by intermediate-mass black holes (IMBHs) of 10^2--10^5 solar masses. WD-TDEs are considered to generate more powerful and short-lived flares, but their evidence has been lacking. Here we report observations of a fast and luminous X-ray transient EP250702a detected by Einstein Probe. Its one-day-long X-ray peak as luminous as 10^(47-49) erg/s showed strong recurrent flares with hard spectra extending to several tens of MeV gamma-rays, as detected by Fermi/GBM and Konus-Wind, indicating relativistic jet emission. The jet's X-ray dropped sharply from 3 x 10^49 erg/s to around 10^44 erg/s within 20 days (10 days in the source rest frame). These characteristics are inconsistent with any known transient phenomena other than a jetted-TDE evolving over an unprecedentedly short timescale, indicating the disruption of a WD by an IMBH. At late times, a new soft component progressively dominates the X-ray spectrum, exhibiting an extreme super-Eddington luminosity, which possibly originates from an accretion disc. WD-TDEs open a new window for investigating the elusive IMBHs and their surrounding stellar environments, and they are prime sources of gravitational waves in the band of space-based interferometers.
Keywords
Cite
@article{arxiv.2509.25877,
title = {A fast powerful X-ray transient from possible tidal disruption of a white dwarf},
author = {Dongyue Li and Wenda Zhang and Jun Yang and Jin-Hong Chen and Weimin Yuan and Huaqing Cheng and Fan Xu and Xinwen Shu and Rong-Feng Shen and Ning Jiang and Jiazheng Zhu and Chang Zhou and Weihua Lei and Hui Sun and Chichuan Jin and Lixin Dai and Bing Zhang and Yu-Han Yang and Wenjie Zhang and Hua Feng and Bifang Liu and Hongyan Zhou and Haiwu Pan and Mingjun Liu and Stephane Corbel and Sitha K. Jagan and Maria Cristina Baglio and Christopher R. Burns and Floriane Cangemi and Chun Chen and Yehao Cheng and Alexis Coleiro and Francesco Coti Zelati and Sourya R. Das and Zhongnan Dong and Luis Galbany and Noa Grollimund and Daniel Kelson and Dong Lai and Xia Li and Yuan Liu and Alessio Marino and Brenna Mockler and Paul O'Brien and Erlin Qiao and Nanda Rea and Resmi and Jérome Rodriguez and Richard Saxton and Luming Sun and Lian Tao and Tinggui Wang and Yilong Wang and Xuefeng Wu and Dong Xu and Yijia Zhang and Guoying Zhao and Congying Bao and Zhiming Cai and Yehai Chen and Yong Chen and Bertrand Cordier and Chenzhou Cui and Weiwei Cui and Zhou Fan and He Gao and Giancarlo Ghirlanda and Ju Guan and Dawei Han and Jinxin Hao and Jingwei Hu and Maohai Huang and Yong-Feng Huang and Shumei Jia and Ge Jin and Stefanie Komossa and Chengkui Li and Zhixing Ling and Congzhan Liu and Heyang Liu and Huaqiu Liu and Fangjun Lu and Kirpal Nandra and Jan-Uwe Ness and Arne Rau and Jeremy Sanders and Liming Song and Roberto Soria and Shengli Sun and Xiaojin Sun and Yuyin Tan and Eleonora Troja and Sixiang Wen and Haitao Xu and Changbin Xue and Yongquan Xue and Yi-Han Iris Yin and Chen Zhang and Shuang-Nan Zhang and Yonghe Zhang},
journal= {arXiv preprint arXiv:2509.25877},
year = {2025}
}
Comments
submitted on 19 October 2025, accepted for publication in Science Bulletin on 12 December 2025