2026-02-09 中国科学院（CAS）
Artist’s impression of the Einstein Probe satellite catching an intermediate black hole, tearing apart a white dwarf, and producing a relativistic jet. (Image by Einstein Probe Science Center, National Astronomical Observatories, CAS/Sci Visual)
＜関連情報＞
- https://english.cas.cn/newsroom/research_news/phys/202602/t20260206_1149909.shtml
- https://www.sciencedirect.com/science/article/abs/pii/S2095927325013271
白色矮星の潮汐破壊によると考えられる高速で強力なX線トランジェント A fast powerful X-ray transient from possible tidal disruption of a white dwarf
Dongyue Li, Wenda Zhang, Jun Yang, Jin-Hong Chen, Weimin Yuan, Huaqing Cheng, Fan Xu, Xinwen Shu, Rong-Feng Shen, Ning Jiang, Jiazheng Zhu, Chang Zhou, Weihua Lei, Hui Sun, Chichuan Jin, Lixin Dai, Bing Zhang, Yu-Han Yang, Wenjie Zhang, Hua Feng…Yonghe Zhang
Science Bulletin Available online: 8 January 2026
DOI:https://doi.org/10.1016/j.scib.2025.12.050
Abstract
Stars getting close enough to 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 102–105solar 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 1047-49 erg s−1 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-rays dropped sharply from 3×1049 erg s−1 to around 1044 erg s−1 within 20 days (10 days in the source rest frame). These characteristics are inconsistent with any previously known transient phenomena. We suggest that this fast-evolving event over the unprecedentedly short timescale arises likely from disruption of a WD by an IMBH. At late times, a soft component progressively dominates the X-ray spectrum, reaching a luminosity as high as 1044 erg s−1, which is consistent with being extreme super-Eddington emission from an accretion disk expected to form in an IMBH-WD TDE. 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.
