Cross correlations with cosmic dispersion measures and large-scale structures
Speaker: Masato Shirasaki (NAOJ)
Abstract:
Fast radio bursts (FRBs) are transient radio signals characterized by millisecond-duration pulses. Although their physical origin remains uncertain, FRBs have garnered significant attention as a promising next-generation cosmological probe. The arrival times of FRB pulses are dispersed due to the propagation of light through intervening electron plasma. This delay is proportional to the column density of free electrons along the line of sight to the source, a quantity known as the dispersion measure (DM). In this talk, I will discuss the correlation between FRB dispersion measures and large-scale structures, and explore their potential for mapping free electrons in the universe. Using 133 localized FRBs and the public galaxy catalog from the Two Micron All Sky Survey (2MASS), we perform a cross-correlation analysis involving cosmic dispersion measures, providing key insights into baryonic feedback effects around galaxies. Our measurements are consistent with a null detection on scales of 0.01–1 Mpc/h; however, the smallest-scale measurement shows tension with theoretical predictions based on the IllustrisTNG hydrodynamical simulation. We use this information to constrain the gas-to-halo mass relation for halos with masses of 10^12-10^13 Msun. Our results demonstrate that galaxy–FRB cross-correlations offer a stringent test of feedback models in hydrodynamical galaxy-formation simulations.