Probing the intergalactic turbulence with fast radio bursts

TL;DR

This paper demonstrates that fast radio bursts can be used to probe intergalactic turbulence, revealing a Kolmogorov power spectrum and large-scale electron density fluctuations in the IGM.

Contribution

It introduces a novel method of analyzing FRB dispersion measures to statistically characterize intergalactic turbulence.

Findings

FRBs show large, correlated DM fluctuations across multiple scales.

The structure function of DMs follows a Kolmogorov power-law.

Intergalactic turbulence likely has an outer scale around 100 Mpc.

Abstract

The turbulence in the diffuse intergalactic medium (IGM) plays an important role in various astrophysical processes across cosmic time, but it is very challenging to constrain its statistical properties both observationally and numerically. Via the statistical analysis of turbulence along different sightlines toward a population of fast radio bursts (FRBs), we demonstrate that FRBs provide a unique tool to probe the intergalactic turbulence. We measure the structure function (SF) of dispersion measures (DMs) of FRBs to study the multi-scale electron density fluctuations induced by the intergalactic turbulence. The SF has a large amplitude and a Kolmogorov power-law scaling with angular separations, showing large and correlated DM fluctuations over a range of length scales. Given that the DMs of FRBs are IGM dominated, our result tentatively suggests that the intergalactic turbulence has a Kolmogorov power spectrum and an outer scale on the order of $100$ Mpc.