Peculiar Motions of Galaxy Clusters in the Regions of Superclusters of galaxies

TL;DR

This study analyzes the peculiar motions of galaxy clusters within and beyond superclusters using SDSS data, revealing significant velocities influenced by gravitational interactions and large-scale structures.

Contribution

The paper provides new measurements of peculiar velocities of galaxy clusters in specific superclusters, highlighting the impact of large-scale structures on cluster motions.

Findings

Significant peculiar velocities observed within superclusters.

No peculiar velocity detected for the most massive cluster in CrB.

Clusters outside large structures show negligible peculiar velocities.

Abstract

We present results of the study of peculiar motions of 57 clusters and groups of galaxies in the regions of the Corona Borealis (CrB), Bootes (Boo), Z5029/A1424, A1190, A1750/A1809 superclusters of galaxies and 20 galaxy clusters located beyond massive structures ($0.05<z<0.10$). Using the SDSS (Data Release 8) data, a sample of early-type galaxies was compiled in the systems under study, their fundamental planes were built, and relative distances and peculiar velocities were determined. Within the galaxy superclusters, significant peculiar motions along the line of sight are observed with rms deviations of $652\pm50$~km s$^{-1}$---in CrB, $757\pm70$~km s$^{-1}$---in Boo. For the most massive A2065 cluster in the CrB supercluster, no peculiar velocity was found. Peculiar motions of other galaxy clusters can be caused by their gravitational interaction both with A\,2065 and with the A2142 supercluster. It has been found that there are two superclusters projected onto each other in the region of the Bootes supercluster with a radial velocity difference of about 4000~km s$^{-1}$. In the Z5029/A1424 supercluster near the rich Z5029 cluster, the most considerable peculiar motions with a rms deviation of $1366\pm170$~km s$^{-1}$ are observed. The rms deviation of peculiar velocities of 20 clusters that do not belong to large-scale structures is equal to $0\pm20$~km s$^{-1}$. The whole sample of the clusters under study has the mean peculiar velocity equal to $83\pm130$~km s$^{-1}$ relative to the cosmic microwave background.