The Effect of Dark Matter-Dark Radiation Interactions on Halo Abundance: A Press-Schechter

We study halo mass functions with the Press-Schechter formalism for interacting dark matter models, where matter power spectra are damped due to dark acoustic oscillations in the early universe. After adopting a smooth window function, we calibrate the analytical model with numerical simulations from the "effective theory of structure formation" (ETHOS) project and fix the model parameters in the high-mass regime, M-h greater than or similar to 3 x 10(10) M-circle dot. We also perform high-resolution cosmological simulations with halo masses down to M-h similar to 10(8) M-circle dot to cover a wide mass range for comparison. Although the model is calibrated with ETHOS1 and cold dark matter simulations for high halo masses at redshift z = 0, it successfully reproduces simulations for two other ETHOS models in the low-mass regime at low and high redshifts. As an application, we compare the cumulative number density of halos to that of observed galaxies at z = 6, and find that the interacting dark matter models with a kinetic decoupling temperature below 0.5 keV is disfavored. We also perform the abundance-matching analysis and derive the stellar-halo mass relation for these models at z = 4. Suppression in halo abundance leads to less massive halos that host observed galaxies in the stellar mass range M-* similar or equal to 10(5)-10(7) M-circle dot.