Galaxy triplets in the Local Supercluster. 2. Virial masses and sum of individual masses

Karachentseva, VE, 1Melnyk, OV, 1Vavilova, IB, Makarov, DI
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2005, 21(3):217-230
Language: Russian
Abstract: 

For the components of 173 triplets of the Local Supercluster (LS) we derived estimates of individual masses which lie within the standard radius and ratios M25/L. The median value of M25/L= 4.8M/L by all galaxy types does not differ significantly from the values obtained for the triplet components of other samples and samples of isolated galaxies (from 4.2M/L to 4.9M/L). The median value of virial mass-to-luminosity ratio for the LS triplets is equal to 35M/L, which is in good agreement with the estimates ⟨Mvir/L⟩ = 31M/L and ⟨Morb/L⟩ = 34M/L obtained for the nearest groups of the Local Volume (Karachentsev I.D. The Local Group and Other Neighboring Galaxy Groups // Astron. J.— 2005.— 129, N 1.— P. 178—188). Median ratio of virial mass to the sum of individual masses of components {Mvir/ΣM25}1/2 for the LS triplets is equal to 7. It is suggested that hypothesis on hidden mass located in the large individual halos can remove the discrepancy between the values of virial mass and sum of individual masses. Another samples of triplets show a significant difference between the values of virial mass and sum of individual masses (10—40 times). This difference explained by the selection effects connected with distance or by morphological composition of samples.

Keywords: galaxy triplets