The globular cluster mass function as a remnant of violent birth

The log-normal shape of the mass function for metal-poor halo globular clusters is proposed to result from an initial M -2 power law modified rapidly by evaporation, collisions with clouds, and mutual cluster interactions in the dense environment of a redshift z ∼ 5-15 disk galaxy. Galaxy interactions subsequently spray these clusters into the galaxy group environment, where they fall into other growing galaxies and populate their halos. Clusters forming later in z ∼ 2-5 galaxies, and those formed during major mergers, produce metal-rich globulars. Monte Carlo models of evolving cluster populations demonstrate the early formation of a log-normal mass function for typical conditions in high-redshift galaxies. © 2010. The American Astronomical Society. All rights reserved.