Relative distances and peculiar velicities 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 $\Lambda$ cold dark matter ($\Lambda$CDM) model (${\Omega }_m=0.3$, $H_0=70$~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 $\pm 0.0173$ ($N$ = 140), which corresponds to a deviation of $70\pm 2.8$~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)~$\times 10^{44}$~erg/s, this quantity turned out to be $70\pm 2.1$~km~s${}^{-1}$ Mpc${}^{-1}$. The root-mean-square deviations of peculiar velocities with quadratic accounting for errors are $<V_{pec}^2{>}^{1/2}$ = $714\pm 7$~km/s and $600\pm 7$~km/s, respectively. For five large superclusters of galaxies from the SDSS region, the average peculiar velocity relaive to the CMB reference frame is $+240\pm 250$~km/s. We detected no outflow of galaxy systems from the void (Giant Void, $\alpha \approx 13^h,\delta \approx 40^{\circ },z\approx 0.107$) formed by groups and clusters of galaxies.

10 pages, 5 figures. Accepted for publication in Astronomy Reports