The globular cluster distributions in the Galaxy, M31 and M87: are many globulars disappeared to the galactic centres?

Abstract

The radial distribution of globular clusters in our Galaxy, M31 and M87 is studied and compared with that of halo stars. The globular cluster distributions seem significantly flatter than those of the stars bulge. Assuming this is a consequence of an evolution of the globular cluster distribution in these galaxies, a comparison with the (unevolved) stellar distribution allows us to obtain estimates of the number and total mass of clusters lost, which are possibly gone to feed the massive central objects present in these galaxies. It results that the cluster systems studied should have been initially about one third and one forth richer than now in our Galaxy and in M31, respectively, and twice as abundant in M87. The estimated mass of globular clusters lost is compatible with the galactic nucleus masses.