A blue tilt in the globular cluster system of the Milky Way‐like galaxy NGC 5170

Here, we present Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging, in the B and I bands, of the edge‐on Sb/Sc galaxy NGC 5170. Excluding the central disc region, we detect 142 objects with colours and sizes typical of globular clusters (GCs). Our main result is the discovery of a ‘blue tilt’ (a mass–metallicity relation), at the 3σ level, in the metal‐poor GC subpopulation of this Milky Way like galaxy. The tilt is consistent …