Vol 20, No 12

The relaxation of galaxy clusters at redshift z = 0 in IllustrisTNG simulation

Chao Li, Ling Zhu, Rui Guo


Abstract We study the dynamical states of the 30 most massive galaxy clusters in the TNG100 simulation at redshift z = 0 using three types of tracers: stars, dark matter particles and satellite galaxies. If the massive galaxy cluster is spherically symmetric and relaxed, we can obtain the underlying total mass distribution accurately from its dynamical tracers using the spherical Jeans equations. Although the three tracers of clusters have very different number densities, velocity dispersions and anisotropies, they still trace the same total mass profile. We obtain the total mass profiles of clusters using these tracers separately and compare them with the true mass distributions. We find that: (1) the kinematics of dark matter trace the total mass of all clusters well and the mass inferred from dark matter are generally consistent with the true mass profiles with relative deviations smaller than ∼ 25% at all radii; (2) stars in ∼ 60% massive clusters are approaching equilibrium and the total mass of these clusters inferred from stars have relative deviations smaller than ∼ 50% at all radii. Stellar substructures are rich and the mass inferred from stars tend to be over-estimated in the inner region; and (3) satellite galaxies are unrelaxed in the inner region and become more relaxed as the radius increases. The total mass inferred from satellites are under-estimated in all regions.


Keywords galaxies: clusters: general — galaxies: clusters: dynamical tracers — methods: numerical 1 INTRODUCTION Galaxy clusters are the largest known gravitational bound structures in the u niverse. According to the standard bottom-up scenario of structure formati

Full Text

  • There are currently no refbacks.