Hydrodynamical Simulation of Clusters of Galaxies in X-Ray, mm, and submm Bands: Determination of Peculiar Velocity and the Hubble Constant

Abstract

We have performed a series of simulations of clusters of galaxies on the basis of the smoothed particle hydrodynamics technique in a spatially flat cold dark matter universe with Ω0 =0.3, λ0 =0.7, and H0=70 km s−1 Mpc−1 as one of the most successful representative cosmological scenarios. In particular, we focused on the Sunyaev–Zel'dovich effect in submm and mm bands, and estimated the reliability of the estimates of the global Hubble constant H0 and the peculiar velocity of clusters vr. Our simulations indicate that the fractional uncertainties of the estimates of H0 amount to ∼ 20%, mainly due to the departure from the isothermal and spherical gas density distribution. We find a systematic underestimate bias of H0 by ∼ 20% for clusters at z ≈ 1, but not at z ≈ 0. The gas temperature drop in the central regions of our simulated clusters leads to an underestimate bias of vr by ∼ 5% at z ≈ 0 and by ∼ 15% at z ≈ 1 in addition to the statistical errors of the comparable amount due to the non-spherical gas profile.