The SLUGGS survey: exploring the metallicity gradients of nearby early-type galaxies to large radii

摘要: Stellar metallicity gradients in the outer regions of galaxies are a critical tool for disentangling contributions in-situ and ex-situ formed stars. In two-phase galaxy formation scenario, initial gas collapse creates steep gradients, while accretion stars satellites tends to flatten these outskirts, particularly massive galaxies. This work presents first compilation extended profiles over wide range mass. We use DEIMOS spectrograph on Keck telescope multi-slit mode obtain radial stellar 22 nearby early-type From calcium triplet lines near-infrared we measure starlight up 3 effective radii. find relation between gradient mass, sense that lower mass systems show steeper than more result is consistent with picture which ratio less as consequence smaller contribution by accretion. addition, infer correlation strength feature function slope recent models literature.