Periodic activity from a fast radio burst source

Abstract: Fast radio bursts (FRBs) are bright, millisecond-duration radio transients originating from extragalactic distances. Their origin is unknown. Some FRB sources emit repeat bursts, ruling out cataclysmic origins for those events. Despite searches for periodicity in repeat burst arrival times on time scales from milliseconds to many days, these bursts have hitherto been observed to appear sporadically, and though clustered, without a regular pattern. Here we report the detection of a $16.35\pm0.15$ day periodicity (or possibly a higher-frequency alias of that periodicity) from a repeating FRB 180916.J0158+65 detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project (CHIME/FRB). In 38 bursts recorded from September 16th, 2018 through February 4th, 2020, we find that all bursts arrive in a 5-day phase window, and 50% of the bursts arrive in a 0.6-day phase window. Our results suggest a mechanism for periodic modulation either of the burst emission itself, or through external amplification or absorption, and disfavour models invoking purely sporadic processes.

• The paper identifies a 16.35-day periodicity in FRB 180916.J0158+65 based on 38 observed bursts.
• It employs Pearson's χ² test with control studies to robustly detect non-uniform burst distributions.
• The findings suggest potential binary interactions or internal astrophysical mechanisms affecting FRB activity.

Periodic Activity from a Fast Radio Burst Source

The paper "Periodic Activity from a Fast Radio Burst Source" discusses the detection and analysis of periodic behavior in FRB 180916.J0158+65, a source of fast radio bursts (FRBs) identified by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Fast Radio Burst Project. This analysis is significant for the study of FRBs, which are transient radio pulses of millisecond duration originating from extragalactic distances.

Key Findings

The research presented in this paper indicates a periodicity of $16.35 \pm 0.15$ days in the bursts from FRB 180916.J0158+65, observed over a range of 38 bursts between September 2018 and February 2020. This discovery is significant as it marks the first identification of periodic behavior in FRBs, suggesting a modification in the theoretical understanding of their origins. The bursts predominantly occur in a five-day phase within this period, with half of the bursts arriving in a narrower 0.6-day window, hinting at potential astrophysical mechanisms driving this periodic behavior.

Methodology

To discern this periodicity, the authors employed a statistical analysis of the burst arrival times using a Pearson's $\chi^2$ test to assess deviation from a uniform distribution. This approach revealed a statistically significant peak in the periodogram at 16.35 days. Control studies using mock datasets and random samples from Galactic pulsars failed to reproduce a similarly significant periodicity, adding weight to the argument that the detected periodicity is not an artifact of instrumental or observational bias.

Implications

The detection of a periodicity suggests that mechanisms beyond purely sporadic processes drive the burst activity of FRB 180916.J0158+65. The paper presents various hypotheses to explain this periodicity, such as orbital motion involving a neutron star (NS) in a binary system with a companion, possibly due to interaction with companion star winds or material in the orbital path. Alternatively, mechanisms involving internal periodic processes, such as rotational or precessional dynamics, could also account for the observed pattern. These hypotheses, if validated, could inform models of repeating FRB sources and potentially differentiate them from non-repeating sources.

Future Directions

The confirmation of this periodic pattern introduces new questions about the astrophysical nature of FRBs. Future observations aiming for multi-frequency radio wavelength studies will help refine our understanding of spectral variation across the periodic cycle. Additionally, studying similar periodicities in other known repeaters may aid in evaluating whether such periodicity is a common characteristic among all repeating FRBs and help distinguish the physical scenarios that could produce such phenomena.

Given the paper's methods and findings, further theoretical work to bridge observations with astrophysical models will likely be forthcoming. Such models need to account not only for the periodic behavior but also for the variations observed in other properties of the emitted radio bursts. Understanding the role of potential companions or environments will be pivotal in achieving a comprehensive understanding of these enigmatic cosmic phenomena. This research opens pathways for probing more exotic physics involving compact objects like neutron stars or black holes in binary or multi-body systems.