A search for intergalactic globular clusters in the Local Group.
DI TULLIO ZINN G. and ZINN R.
Abstract (from CDS):
The whole Sloan Digital Sky Survey (SDSS, 14,555 deg2) has been searched for intergalactic globular clusters (IGCs) in the Local Group (LG). Using optical, infrared, and ultraviolet photometric selection criteria and photometric redshifts, the 2.1 x 108 objects in the SDSS Galaxy Catalog were reduced to only 183,791 brighter than r0 = 19 that might be GCs. Visual examination of their SDSS images recovered 84% of the confirmed GCs in M31 and M33 and yielded 17 new GC candidates, 5 of them of high confidence, which we could confirm as GCs in MegaPrime images from the Canada-France-Hawaii Telescope. These 5 GCs are within M31's halo, but the other 12 candidates are not close to LG galaxies or galaxies within 3 Mpc of the LG. Even though this search covers only one-third of the sky and some GCs could have been missed, it suggests that the LG does not contain a large population of IGCs more luminous than MV ∼ -6 . In the direction of the M81 Group, the search yielded five candidate GCs, probable members of that group.
galaxies: groups: general - galaxies: individual: M31 - globular clusters: general - Local Group