The Absence of Periodicity in Repeating FRB

TL;DR

Extensive analysis of over 1500 bursts from FRB 121102 and FRB 20201124A shows no evidence of periodicity, challenging models that involve rotating neutron stars with strict periodic signals.

Contribution

This study provides the first comprehensive search for periodicity in large datasets of repeating FRBs, demonstrating the absence of periodic signals and supporting models without intrinsic periodicity.

Findings

No periodicity detected in FRB 121102 and FRB 20201124A datasets.

Periodogram analysis sensitive to slow frequency drifts shows no underlying periodic signals.

Results challenge models that rely on strict rotational periodicity of neutron stars.

Abstract

Popular Fast Radio Burst models involve rotating magnetized neutron stars, yet no rotational periodicities have been found. Small datasets exclude exact periodicity in FRB 121102. Recent observations of over 1500 bursts from each of FRB 121102 and FRB 20201124A also have not found periodicity. Periodograms of events with cosine-distributed random offsets as large as $\pm 0.6 P$ from a strict period $P$ would still reveal the underlying periodicity. The sensitivity of periodograms of long data series, such as bursts observed on multiple days, to slow frequency drifts is mitigated by considering individual observing sessions, and results are shown for FRB 121102. Models of repeating FRB without intrinsic periodicity are considered, as are models of apparently non-repeating FRB.