Probing cosmology and gastrophysics with fast radio bursts: cross-correlations of dark matter haloes and cosmic dispersion measures

For future surveys of fast radio bursts (FRBs), we clarify information available from cosmic dispersion measures (DMs) through cross-correlation analyses of foreground dark matter haloes (hosting galaxies and galaxy clusters) with their known redshifts. With a halo-model approach, we predict that the cross-correlation with cluster-sized haloes is less affected by the details of gastrophysics, providing robust cosmological information. For less massive haloes, the cross-correlation at angular scales of <10 arcmin is sensitive to gas expelled from the halo centre due to galactic feedback. Assuming 20 000 FRBs over 20 000 deg(2) with a localization error being 3 arcmin, we expect that the cross-correlation signal at halo masses of 10(12)-10(14) M-circle dot can be measured with a level of similar to 1 per cent precision in a redshift range of 0 < z < 1. Such precise measurements enable one to put a 1.5 per cent level constraint on sigma(8) (Omega(M) /0.3)0.5 and a 3 per cent level constraint on (Omega(b) /0.049)(h /0.67)(f(e) /0.95) (sigma(8), Omega(M), Omega(b), h, and f e are the linear mass variance smoothed at 8 h(-1) Mpc, mean mass density, mean baryon density, the present-day Hubble parameter, and fraction of free electrons in cosmic baryons today, respectively), whereas the gas-to-halo mass relation in galaxies and clusters can be constrained with a level of 10-20 per cent. Furthermore the cross-correlation analyses can break the degeneracy among Omega(b), h, and f(e), inherent in the DM-redshift relation. Our proposal opens new possibilities for FRB cosmology, while it requires extensive galaxy redshift catalogues and further improvement of the halo model.