2022MNRAS.512.1730S

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 20000 deg² with a localization error being 3 arcmin, we expect that the cross-correlation signal at halo masses of 10¹²-10¹⁴ M_☉ can be measured with a level of ∼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 σ₈(Ω_M/0.3)^0.5 and a 3 per cent level constraint on (Ω_b/0.049)(h/0.67)(f_e/0.95) (σ₈, Ω_M, Ω_b, h, and f_e are the linear mass variance smoothed at 8 h^–1Mpc, 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 Ω_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.