An Intermediate-mass Black Hole Lurking in A Galactic Halo Caught Alive during Outburst
Abstract
Stellar-mass and supermassive black holes abound in the Universe, whereas intermediate-mass black holes (IMBHs) of ~10^2-10^5 solar masses in between are largely missing observationally, with few cases found only. Here we report the real-time discovery of a long-duration X-ray transient, EP240222a, accompanied by an optical flare with prominent H and He emission lines revealed by prompt follow-up observations. Its observed properties evidence an IMBH located unambiguously in the halo of a nearby galaxy and flaring by tidally disrupting a star -- the only confirmed off-nucleus IMBH-tidal disruption event so far. This work demonstrates the potential of sensitive time-domain X-ray surveys, complemented by timely multi-wavelength follow-ups, in probing IMBHs, their environments, demographics, origins and connections to stellar-mass and supermassive black holes.
Keywords
Cite
@article{arxiv.2501.09580,
title = {An Intermediate-mass Black Hole Lurking in A Galactic Halo Caught Alive during Outburst},
author = {C. -C. Jin and D. -Y. Li and N. Jiang and L. -X. Dai and H. -Q. Cheng and J. -Z. Zhu and C. -W. Yang and A. Rau and P. Baldini and T. -G. Wang and H. -Y. Zhou and W. Yuan and C. Zhang and X. -W. Shu and R. -F. Shen and Y. -L. Wang and S. -X. Wen and Q. -Y. Wu and Y. -B. Wang and L. L. Thomsen and Z. -J. Zhang and W. -J. Zhang and A. Coleiro and R. Eyles-Ferris and X. Fang and L. C. Ho and J. -W. Hu and J. -J. Jin and W. -X. Li and B. -F. Liu and F. -K. Liu and M. -J. Liu and Z. Liu and Y. -J. Lu and A. Merloni and E. -L. Qiao and R. Saxton and R. Soria and S. Wang and Y. -Q. Xue and H. -N. Yang and B. Zhang and W. -D. Zhang and Z. -M. Cai and F. -S. Chen and H. -L. Chen and T. -X. Chen and W. Chen and Y. -H. Chen and Y. -F. Chen and Y. Chen and B. Cordier and C. -Z. Cui and W. -W. Cui and Y. -F. Dai and H. -C. Ding and D. -W. Fan and Z. Fan and H. Feng and J. A. Garcia and J. Guan and D. -W. Han and D. -J. Hou and H. -B. Hu and M. -H. Huang and J. Huo and S. -M. Jia and Z. -Q. Jia and B. -W. Jiang and G. Jin and X. Kong and E. Kuulkers and W. -H. Lei and C. -K. Li and J. -F. Li and L. -H. Li and M. -S. Li and W. Li and Z. -D. Li and T. -Y. Lian and Z. -X. Ling and C. -Z. Liu and H. -Y Liu and H. -Q. Liu and J. -F. Liu and Y. Liu and F. -J. Lu and L. -D. Luo and J. Ma and X. Mao and H. -Y. Mu and K. Nandra and P. O'Brien and H. -W. Pan and X. Pan and G. -J. Qin and N. Rea and J. Sanders and L. -M. Song and H. Sun and S. -L. Sun and X. -J. Sun and Y. -Y. Tan and Q. -J. Tang and Y. -H. Tao and B. -C. Wang and J. Wang and J. -F. Wang and L. Wang and W. -X. Wang and Y. -S. Wang and Z. -X. Wang and Q. -W. Wu and X. -F. Wu and H. -T. Xu and J. -J. Xu and X. -P. Xu and Y. -F. Xu and Z. Xu and C. -B. Xue and S. -J. Xue and Y. -L. Xue and A. -L. Yan and X. -T. Yang and Y. -J. Yang and J. Zhang and M. Zhang and S. -N. Zhang and Y. -H. Zhang and Z. Zhang and Z. Zhang and Z. -L. Zhang and D. -H. Zhao and H. -S. Zhao and X. -F. Zhao and Z. -J. Zhao and J. Zheng and Q. -F. Zhu and Y. -X. Zhu and Z. -C. Zhu and H. Zou},
journal= {arXiv preprint arXiv:2501.09580},
year = {2025}
}
Comments
64 pages, 15 figures, submitted