Mapping accreted stars in early-type galaxies across the mass–size plane

ABSTRACT Galaxy mergers are instrumental in dictating the final mass, structure, stellar populations, and kinematics of galaxies. Cosmological galaxy simulations indicate that most massive galaxies at z = 0 dominated by high fractions ‘ex-situ’ stars, which formed first distinct independent galaxies, then subsequently merged into host galaxy. Using spatially resolved MUSE spectroscopy we quantify map ex-situ stars thirteen early-type We use full spectral fitting together with semi-analytic evolution models to isolate signatures galaxies’ light indicative populations. large field view find all display an increase fraction radius, more extended showing a rapid radial (reaching values between ?30 per cent 100 2 effective radii) compared less compact sources ?5 40 within same radius). These results line predictions from theory suggest should significantly radius fixed mass for