Gravitational redshifts from large-scale structure

Understand

The recent measurement of the gravitational redshifts of galaxies in galaxy clusters by Wojtak et al.

• has opened a new observational window on dark matter and modified gravity.
• By stacking clusters this determination effectively used the line of sight distortion of the cross-correlation function of massive galaxies and lower mass galaxies to estimate the gravitational redshift profile of clusters out to 4 Mpc/h.
• Here we use a halo model of clustering to predict the distortion due to gravitational redshifts of the cross-correlation function on scales from 1 - 100 Mpc/h.