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astro-ph.HE · High Energy Astrophysical Phenomenaastro-ph.IM · Instrumentation and Methods for Astrophysics

Fitted DM rose with fitted peak frequency after daily means were removed from 272 CHIME bursts of FRB 20220912A

Burst structure can affect fitted dispersion measure (DM). We tested whether fitted DM and fitted spectral peak frequency varied together within observed days in CHIME/FRB Catalog 2, release 20251231. We used one record per burst, removed each day's means, and gave each day total observation weight one. Quality cuts and a minimum of five days with multiple bursts selected three sources before slopes were calculated. FRB 20220912A had 272 bursts on 84 informative days. Its slope was 3.864 pc cm^-3 per frequency doubling. The 95% interval from resampling days was 2.223 to 5.610. The interval from resampling calendar weeks was 2.185 to 5.651. A within-day permutation test gave p=0.00002 and Holm p=0.00006 across three sources, under the within-day exchangeability assumption. This small simulated tail count has large relative Monte Carlo error. Removing any one day gave slopes from 3.397 to 4.120. Fits with one component per burst and a common control for time within a day also stayed positive. The two other sources had intervals that included zero. This result measures an aggregate relation between catalog fit values. Shared fit errors, burst structure, selection, and plasma changes remain possible causes. It does not establish a physical DM change. The package contains the analysis plan, code, input provenance, event audit, transformed data, tests, and figures.

fast radio bursts · FRB 20220912A · CHIME/FRB Catalog 2 · dispersion measure · spectral peak frequency · within-day association · permutation test · reproducible astronomy

Admitted 3 citing publications

References

7
  1. usesdoi:10.11570/25.0066

    We used the public CHIME/FRB Catalog 2 CSV, release 20251231. The package records its source URL and SHA-256.

  2. usesdoi:10.48550/arXiv.2601.09399

    The catalog paper defines the burst fits, spectral peaks, and quality flags used in this study.

  3. doi:10.48550/arXiv.2605.08410

    This paper tests DM changes over time in repeaters. Our test removes daily means and asks a separate question.

  4. doi:10.3847/1538-4357/ac33ac

    This paper describes burst morphology and its effects on CHIME burst measurements.

  5. doi:10.48550/arXiv.2604.01825

    This paper studies burst-structure contributions to fitted DM in FRB 20220912A.

  6. doi:10.48550/arXiv.2604.09098

    This paper reports a temporal DM slope in a selected CHIME/Pulsar sample of FRB 20220912A. Our within-day catalog association does not test that slope.

  7. usesSix reported CHIME Catalog 2 DM slopes kept their sign with equal day weights and after one-day deletion sci:sha256:552529f329ee82f082fc26b365d0cb025e1688d82a72f9288708ebc3762eec6f

    Its provenance record supplied the catalog release URL and hash. We wrote new code for a separate test of the relation between DM and spectral peak frequency within days.

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