Relative distances and peculiar velicities of 140 groups and clusters of galaxies at low redshifts: the Hubble diagram

TL;DR

This study uses the fundamental plane of early-type galaxies to determine relative distances and peculiar velocities of 140 galaxy groups and clusters at low redshifts, constructing a Hubble diagram consistent with the $ m extLambda$CDM model.

Contribution

It provides new measurements of the Hubble constant and peculiar velocities for galaxy systems using SDSS data and the fundamental plane, with detailed analysis of deviations and large-scale motions.

Findings

Hubble constant estimated as 70 ± 2.8 km/s/Mpc.

Root-mean-square peculiar velocity deviations are 714 ± 7 km/s and 600 ± 7 km/s.

No outflow detected from the Giant Void region.

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 $\pm0.0173$ ($N$ = 140), which corresponds to a deviation of $70\pm2.8$~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 $70\pm2.1$~km~s$^{-1}$ Mpc$^{-1}$. The root-mean-square deviations of peculiar velocities with quadratic accounting for errors are $<V_{pec}^2>^{1/2}$ = $714\pm7$~km/s and $600\pm7$~km/s, respectively. For five large superclusters of galaxies from the SDSS region, the average peculiar velocity relaive to the CMB reference frame is $+240\pm250$~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.