Baryon Acoustic Oscillations Analyses with Density-split Statistics

Accurate modeling for the evolution of the baryon acoustic oscillation (BAO) is essential for using it as a standard ruler to probe cosmology. We explore the nonlinearity of the BAO in different environments using the density-split statistics and compare them to the case of the conventional two-point correlation function (2PCF). We detect density-dependent shifts for the position of the BAO with respect to its linear version using halos from N-body simulations. Around low/high-densities, the scale of the BAO expands/contracts due to nonlinear peculiar velocities. As the simulation evolves from redshift 1 to 0, the difference in the magnitude of the shifts between high- and low-dense regions increases from the subpercent to the percent level. The width of the BAO around high density regions increases as the universe evolves, similar to the known broadening of the BAO in the 2PCF due to nonlinear evolution. In contrast, the width is smaller and stable for low density regions. We discuss possible implications for the reconstructions of the BAO in light of our results.