Identifying nearby red nuggets : the unusual globular cluster system of a massive relic galaxy
The most massive galaxies in the universe are thought to form in two phases: an initial, early collapse and giant burst
of central star formation, followed by the later accretion of satellite galaxies that builds up their
stellar and dark matter haloes. The globular cluster systems of such galaxies are believed to form in a similar manner.
The initial central burst forms metal-rich (red) clusters, while more metal-poor
(blue) clusters are brought in by the later accretion of satellites.
This formation process is thought to lead the creation of the double-peaked
colour distributions seen in the globular cluster systems of massive galaxies.
To test this model we studied the globular cluster system of the
massive galaxy NGC 1277 with HST. This galaxy is thought to be a rare "relic" galaxy-
that is a galaxy which completed its early collapse phase but has failed to evolve and accrete
smaller satellite galaxies. Our analysis has revealed a highly unusual globular cluster system
in NGC 1277, one which gives unique insights into the formation and evolutionary processes
of the most massive galaxies.