Simultaneous Dependence of Matter Clustering on Scale and Environment

Abstract

In this work, we propose new statistical tools that are capable of characterizing the simultaneous dependence of the matter clustering on the scale and density environment, which are the environment-dependent wavelet power spectrum (env-WPS) and environment-dependent wavelet cross-correlation (env-WCC). We apply these statistics to the projected 2D dark matter and baryonic gas density fields of the IllustrisTNG simulation at redshifts from z = 3.0 to z = 0.0. Measurement of the env-WPSs indicates that the clustering strengths of both the dark matter and gas increase with density. At all redshifts, we observe that the env-WPS of the gas is suppressed on intermediate and small scales, which is caused by baryonic processes. Furthermore, by computing the environmental bias function, we find that this suppression varies with the environment, scale and redshift. A noteworthy feature is that at z = 0.0, the bias value increases with density on scales 2 k 10 hMpc −1 , which is the reversal of that in earlier times. On the other hand, the env-WCC also shows strong environmental dependence on scales k 2 hMpc −1 and is sensitive to the redshift. We find that at z = 3.0, the coherence of the dark matter and gas decreases with density. At lower redshifts, the coherence in denser environments becomes much higher than that in less dense environments. These results suggest that baryonic processes have less effect on the matter clustering in high-density environments at later times. Obviously, these statistics provide us rich information and hence could improve our understanding of the matter clustering.