Deep Synoptic Array Science: Discovery of the Host Galaxy of FRB 20220912A

[摘要] We report the detection and interferometric localization of the repeating fast radio burst (FRB) source FRB 20220912A during commissioning observations with the Deep Synoptic Array (DSA-110). Two bursts were detected from FRB 20220912A, one each on 2022 October 18 and 2022 October 25. The best-fit position is (R.A. J2000, decl. J2000) = (23:09:04.9, +48:42:25.4), with a 90% confidence error ellipse with radii ±2'' and ±1'' in R.A. and decl., respectively. The two bursts are polarized, and we find a Faraday rotation measure that is consistent with the low value of +0.6 rad m⁻² reported by CHIME/FRB. The DSA-110 localization overlaps with the galaxy PSO J347.2702+48.7066 at a redshiftz= 0.0771, which we identify as the likely host. PSO J347.2702+48.7066 has a stellar mass of approximately 10¹⁰ M _⊙, modest internal dust extinction, and a star formation rate likely in excess of 0.1M _⊙ yr⁻¹. The host-galaxy contribution to the dispersion measure is likely ≲50 pc cm⁻³. The FRB 20220912A source is therefore likely viewed along a tenuous plasma column through the host galaxy.