Understanding the missing clusters problem at the Galactic center. Dissolved cluster(s) detection in the Sgr B1 region.

Abstract

The Milky Way’s center is the closest galaxy nucleus and our Galaxy’s most extreme environment. Although its volume is less than 1% of the one of the Galactic disk, up to 10% of all new-born stars in the Galaxy in the past 100 Myr formed there. Therefore, it constitutes a perfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift galaxies. However, the only two known Galactic center young clusters account for <10% of the expected young stellar mass. Studying Sgr B1, a luminous Galactic center HII region, we find evidence for the presence of several 10^5 solar masses of young stars, probably tracing one or several dissolved young clusters that formed ~10 Myr ago. This is a large step toward a better understanding of star formation at the Galactic center, such as the fate of young clusters, and the possibly different initial mass function in this region.