Cosmology-independent estimate of the fraction of baryon mass in the IGM from fast radio burst observations

Understand

The excessive dispersion measure (DM) of fast radio bursts (FRBs) has been proposed to be a powerful tool to study intergalactic medium (IGM) and to perform cosmography.

• One issue is that the fraction of baryons in the IGM, $f_{\rm IGM}$, is not properly constrained.
• Here we propose a method of estimating $f_{\rm IGM}$ using a putative sample of FRBs with the measurements of both DM and luminosity distance $d_{\rm L}$.
• The latter can be obtained if the FRB is associated with a distance indicator (e.g.