Rui-Nan Li, Zhao Joseph Zhang, Kentaro Nagamine, Yuri Oku, Qin Wu, F. Y. Wang

Extragalactic fast radio bursts (FRBs) have emerged as powerful probes of turbulence within the intergalactic medium (IGM), a phenomenon that plays a crucial role in various cosmological and astrophysical processes. In this study, we employ the structure function (SF) analysis on the dispersion measures (DMs) of over 3,000 FRBs, leveraging the recently released CHIME/FRB Catalog 2 alongside previously observed sources. By comparing our results with mock datasets generated from cosmological simulations, we find excellent agreement at large angular separations. At small angular scales, our findings reveal a potential scaling behavior consistent with a two-dimensional (2D) Kolmogorov power spectrum. From this scaling, we constrain the turbulence outer scale to be on the order of several Mpc, which aligns with theoretical expectations, independent observations of the low-redshift IGM, and cosmological simulations. Ultimately, to conclusively confirm this Kolmogorov-like turbulent cascade and overcome current small-sample statistical limitations, a larger sample of FRBs with sub-arcsecond localization is required.