The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium, which is assumed to dominate the total extragalactic dispersion. While the host galaxy contributions to dispersion measure (DM) appear to be small for most FRBs, in at least one case there is evidence for an extreme magneto-ionic local environment and a compact persistent radio source. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific star formation rate at a redshift z=0.241±0.001. The estimated host galaxy DM ≈903−111+72 pc cm−3, nearly an order of magnitude higher than the average of FRB host galaxies, far exceeds the DM contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host galaxy identifications.
@article{arxiv.2110.07418,
title = {A repeating fast radio burst associated with a persistent radio source},
author = {C. -H. Niu and K. Aggarwal and D. Li and X. Zhang and S. Chatterjee and C. -W. Tsai and W. Yu and C. J. Law and S. Burke-Spolaor and J. M. Cordes and Y. -K. Zhang and S. Ocker and J. -M. Yao and P. Wang and Y. Feng and Y. Niino and C. Bochenek and M. Cruces and L. Connor and J. -A. Jiang and S. Dai and R. Luo and G. -D. Li and C. -C. Miao and J. -R. Niu and R. Anna-Thomas and J. Sydnor and D. Stern and W. -Y. Wang and M. Yuan and Y. -L. Yue and D. -J. Zhou and Z. Yan and W. -W. Zhu and B. Zhang},
journal= {arXiv preprint arXiv:2110.07418},
year = {2022}
}