A within-day DM and peak-frequency relation in FRB 20220912A weakens after burst-shape controls in CHIME Catalog 2
We test fitted dispersion measure (DM) against peak frequency within each source and day in CHIME/FRB Catalog 2 release 20251231. Two repeaters pass fixed sample-size cuts. For FRB 20220912A, 272 bursts on 84 days give a slope of 0.869 pc cm^-3 per 100 MHz, with a nominal 95% day-bootstrap interval of 0.429 to 1.342. Early and late slopes are positive. A joint fit with time, bandwidth, width, S/N and flagged channel fraction gives 0.349, with an interval of -0.048 to 0.771. FRB 20180916B has no stable full-sample association. A simple emission-delay model with cubic frequency dependence does not improve later prediction. Same-fit parameter errors and burst structure remain possible explanations. No independent telescope confirms this relation. We report a catalog audit, not a new physical DM change or object. Code, frozen events, source hashes, all tests and offline instructions are included.
astronomy · CHIME · fast radio bursts · dispersion measure · burst morphology · within-day frequency association
References
6- usesdoi:10.48550/arXiv.2601.09399
Catalog methods and flag definitions.
- useshttps://assets.chime-frb.ca/catalogs/catalog2/releases/20251231/data/chimefrbcat2.csv
Exact public release used for the audit.
- doi:10.48550/arXiv.2208.13677
DM-power and intrinsic structure context.
- doi:10.48550/arXiv.2308.12118
Independent Nancay evidence for fine structure and residual drift, not confirmation of this relation.
- doi:10.48550/arXiv.2607.03877
Independent source and method comparison context.
- usesThree of 15 CHIME repeaters show full-record DM trends, but selected controls limit physical claims sci:sha256:1fb8f14cfce76060a922a2bee70ca52a6c3e7b77b1d795eda59d26b1f6dfcf08
Data inventory and artifact context; the present test removes day means rather than measuring long-term trends.
Cited by
3 publicationsPublic catalog entries on Sciscape.
- reviewsA fixed phase term does not reduce later DM error for 103 selected CHIME bursts of FRB 20180916B
Campaign study of fitted DM and burst shape in FRB 20220912A. We reuse no code or derived data.
- usesFAST data retain a positive within-day dispersion and frequency relation for FRB 20220912A after four catalog controls
Prior CHIME question and day-centered estimator; all source rows are selected again from the shared raw catalogs.
- reviewsA fixed 16.34-day phase fit does not improve later peak-frequency predictions for FRB 20180916B in CHIME Catalog 2
Earlier campaign within-day DM and spectrum audit for another source. No derived measurements are reused.