Discrete steps in dispersion measures of Fast Radio Bursts

TL;DR

This paper identifies discrete step patterns in the dispersion measures of known Fast Radio Bursts, suggesting a possible origin from a galactic population or man-made sources, with implications for their nature.

Contribution

It introduces the observation of quantized dispersion measures in FRBs and hypothesizes a potential galactic or artificial origin based on these patterns.

Findings

DMs occur in discrete steps centered at specific values

Likelihood of coincidence is estimated at 5 in 10,000

FRBs tend to arrive near the full second, similar to man-made signals

Abstract

Fast Radios Bursts (FRBs) show large dispersion measures (DMs), suggesting an extragalactic location. We analyze the DMs of the 11 known FRBs in detail and identify steps as integer multiples of half the lowest DM found, 187.5cm$^{-3}$ pc, so that DMs occur in groups centered at 375, 562, 750, 937, 1125cm$^{-3}$ pc, with errors observed <5%. We estimate the likelhood of a coincidence as 5:10,000. We speculate that this could originate from a Galaxy population of FRBs, with Milky Way DM contribution as model deviations, and an underlying generator process that produces FRBs with DMs in discrete steps. However, we find that FRBs tend to arrive at close to the full integer second, like man-made perytons. If this holds, FRBs would also be man-made. This can be verified, or refuted, with new FRBs to be detected.