Kavli Affiliate: Kiyoshi Masui
| Summary:
We present the discovery and subsequent 3.2 year monitoring campaign of the repeating fast radio burst FRB 20220529A with CHIME/FRB. We observe a gradual dispersion measure (DM) decline of $-0.881pm0.001~mathrmpc~mathrmcm^-3~mathrmyear^-1$ ($-1.235pm0.001~mathrmpc~mathrmcm^-3~mathrmyear^-1$ in the rest frame), implying a $geq3.5pm0.2$% decrease of the total electron column in the source environment, and we see scattering timescale variations over weeks to years. We observe a short-lived excursion in which the DM rises by $sim 1~mathrmpc~mathrmcm^-3$, immediately preceding a transient $sim 2000~mathrmrad~mathrmm^-2$ Faraday rotation measure (RM) increase previously reported for this source, before returning to its gradual DM decline. We identify a local line-of-sight magnetic field around FRB 20220529A during this DM/RM excursion of $3.4 pm 0.2~mathrmmG$, corresponding to one of the most strongly magnetized FRB environments. We measure a decrease in the linear polarization fraction of FRB 20220529A bursts with decreasing frequency that we attribute to depolarization from multi-path propagation in the source environment. We also place a $5σ$ upper limit on the spectral luminosity of an associated persistent radio source of $leq 5times10^28~mathrmerg~mathrms^-1~mathrmHz^-1$ at 1.5 GHz. These observations are consistent with FRB 20220529A originating from a young ($sim$ years to centuries old) expanding supernova remnant, with short-lived DM and RM variability arising from interactions with the supernova remnant or with a binary companion.
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