Relative Distances and Peculiar Velocities of 140 Groups and Clusters of Galaxies at Low Redshifts: the Hubble Diagram

Abstract

To determine the relative distances and peculiar velocities of 140 groups and clusters of galaxies at low redshifts (z < 0.12), we used the fundamental plane (FP) of early-type galaxies (from the Sloan Digital Sky Survey (SDSS) data). We constructed the Hubble diagram for the relative distances of galaxy groups/clusters versus their radial velocities in the cosmic microwave background (CMB) reference frame in the flat Λ cold dark matter (ΛLCDM) model (Ω_m = 0.3 and H₀ = 70 km s^–1 Mpc^–1). We have found that the standard logarithmic deviation for groups and clusters of galaxies on the Hubble diagram (minus peculiar velocities) is ±0.0173 (N = 140), which corresponds to a deviation of 70 ± 2.8 km s^–1 Mpc^–1 in the Hubble constant. For a sample of galaxy systems (N = 63), the X-ray luminosity of which is in an interval of (0.151‒4) × 10⁴⁴ erg/s, this quantity turned out to be 70 ± 2.1 km s^–1 Mpc^–1. The root-mean-square deviations of peculiar velocities with quadratic accounting for errors are \({{\langle V_{{{\text{pec}}}}^{2}\rangle }^{{1/2}}}\) = 714 ± 7 and 600 ± 7 km/s, respectively. For five large superclusters of galaxies from the SDSS region, the average peculiar velocity relative to the CMB reference frame is +240 ± 250 km/s. We detected no outflow of galaxy systems from the void (Giant Void; α ≈ 13^h, δ ≈ 40°, and z ≈ 0.107) formed by groups and clusters of galaxies.