The half-mass radius of MaNGA galaxies: effect of IMF gradients

ABSTRACT Gradients in the stellar populations (SP) of galaxies – e.g. age, metallicity, initial mass function (IMF) can result gradients stellar-mass-to-light ratio, M*/L. Such imply that distribution and light is different. For old SPs, early-type at z ∼ 0, M*/L are weak if driven by variations age but significantly larger IMF. A gradient which has centre increases estimated total (M*) reduces scale contains half this (Re,*), compared to when ignored. IMF inferred from fitting MILES simple SP models H β, 〈Fe〉, [MgFe], TiO2SDSS absorption lines measured spatially resolved spectra MaNGA survey, fractional change Re,* be than M*, especially more centrally concentrated. The Re,*–M* correlation results accounting for offset smaller sizes 0.3 dex these Comparisons with ‘quiescent’ higher must account evolution (especially IMF) profile before drawing conclusions about how M* evolve. implied merging between present less contrived Re,*/Re 0 closer our IMF-driven calibration unity.