Star-forming galaxies at z∼ 2 and the formation of the metal-rich globular cluster population

We examine whether the super star-forming (super-SF) clumps (R∼ 1–3 kpc; M∼ 108– 109.5 M⊙) now known to be a key component of star-forming galaxies at z∼ 2 could be the formation sites of the locally observed old globular cluster (GC) population. We find that the stellar populations of these super-SF clumps are excellent matches to those of local metal-rich GCs. Moreover, this GC population is known to be associated with the bulges/thick discs of galaxies, and we show that its spatial distribution and kinematics are consistent with the current understanding of the assembly of bulges and thick discs from super-SF clumps at high redshift. Finally, with the assumption that star formation in these clumps proceeds as a scaled-up version of local star formation in molecular clouds, this formation scenario reproduces the observed numbers and mass spectra of metal-rich GCs. The resulting link between the turbulent and clumpy discs observed in high-redshift galaxies and a local GC population provides a plausible co-evolutionary scenario for several of the major components of a galaxy: the bulge, the thick disc and one of the GC populations.