A Cosmic Coincidence: The Power-Law Galaxy Correlation Function

Understand

We model the evolution of galaxy clustering through cosmic time to investigate the nature of the power-law shape of xi(r), the galaxy two-point correlation function.

• Departures from a power law are mainly governed by galaxy pair counts on small scales, subject to non-linear dynamics.
• We assume that galaxies reside within dark matter halos and subhalos and use a semi-analytic substructure evolution model to study subhalo populations within host halos.
• We find that tidal mass loss and, to a lesser degree, dynamical friction deplete the number of subhalos within larger host halos over time by ~90%, just the right amount for achieving a power-law xi(r) at z = 0.