Measuring the circumgalactic gas with fast radio bursts
The distribution of gas around galaxies is poorly constrained and is sensitive to galaxy formation feedback processes. FRBs provide a unique probe of the CGM through the integrated electron density along the line of sight – the dispersion measure (DM). As one of the first few attempts in this direction, we measured the excess DM of nearby (<100 Mpc) low-mass (\(10^{11}-10^{13}\ M_\odot\)) halos using CHIME FRBs by establishing a novel weighted stacking method. We found a 1-2 \(\sigma\) detection of the excess DM at <1-2 virial radii with the current sample of 500 FRBs. With 2000-3000 more FRBs from future CHIME data release, we predict a 4-\(\sigma\) detection, which should be even more significant given the much better localization in the near future.
