Detailed study of the Ursa Major supercluster of galaxies using the 2MASS and SDSS Catalogs

Abstract

We study the infrared (K s band) properties of clusters of galaxies in the Ursa Major supercluster using data from 2MASS (Two-Micron All-Sky Survey) and SDSS (Sloan Digital Sky Survey). We identified three large filaments with mean redshifts of z = 0.051, 0.060, and 0.071. All clusters of the supercluster are located in these filaments. We determined the total K s-band luminosities and masses for 11 clusters of galaxies within comparable physical regions (within a radius R 200 close to the virial radius) using a homogeneous method. We constructed a combined luminosity function for the supercluster in this region, which can be described by the Schechter function with the following parameters: M K * = −24.50 and α = −0.98. The infrared luminosities of the clusters of galaxies correlate with their masses; the M/L K ratios of the systems increase with their masses (luminosities), with most of the Ursa Major clusters of galaxies (particularly the richer ones) closely following the relations derived previously for a large sample of clusters and groups of galaxies. The total mass-to-infrared-luminosity ratio is 52 M ⊙/L ⊙ for six Abell clusters and 49M ⊙/L ⊙ for all of the clusters, except Anon2.