Reconstruction of baryon fraction in intergalactic medium through dispersion measurements of fast radio bursts

Fast radio bursts (FRBs) probe the total column density of free electrons in the intergalactic medium (IGM) along the path of propagation through the dispersion measures (DMs) that depend on the baryon mass fraction in the IGM, i.e. f(IGM). In this letter, we investigate the large-scale clustering information of DMs to study the evolution of f(IGM). When combining with the Planck 2018 measurements, we could give tight constraints on the evolution of f(IGM)(z) from about 10(4) FRBs with the intrinsic DM scatter of 30(1 + z)pc cm(-3) spanning 80 percent of the sky and redshift range z = 0-3. First, we consider the Taylor expansion of f(IGM)(z) up to second order, and find that the mean relative standard deviation sigma(f(IGM)) (math) is about 6.7 per cent. In order to alleviate the dependence on fiducial model, we also adopt non-parametric methods in this work, the local principle component analysis. We obtain the consistent, but weaker constraints on the evolution f(IGM)(z), namely the mean relative standard deviation sigma(f(IGM)) is 21.4 percent. With the forthcoming surveys, this could be a complimentary method to investigate the baryon mass fraction in the IGM.

Automated summary

This study investigates the relationship between fast radio bursts dispersion measures and the evolution of baryon mass fraction in the intergalactic medium. By combining large-scale clustering information with Planck 2018 measurements, tight constraints on the evolution of f(IGM)(z) were obtained. The mean relative standard deviation was found through Taylor expansion and non-parametric methods.