The Dragonfly Wide Field Survey. II. Accurate Total Luminosities and Colors of Nearby Massive Galaxies and Implications for the Galaxy Stellar-mass Function
Miller, Tim B., van Dokkum, Pieter, Danieli, Shany, Li, Jiaxuan, Abraham, Roberto, Conroy, Charlie, Gilhuly, Colleen, Greco, Johnny P., Liu, Qing, Lokhorst, Deborah and Merritt, Allison
Abstract
Stellar-mass estimates of massive galaxies are susceptible to systematic errors in their photometry, due to their extended light profiles. In this study, we use data from the Dragonfly Wide Field Survey to accurately measure the total luminosities and colors of nearby massive galaxies. The low surface brightness limits of the survey (ยตg ? 31 mag arcsec-2 on a 1' scale) allow us to implement a method, based on integrating the 1D surface brightness profile, that is minimally dependent on any parameterization. We construct a sample of 1188 massive galaxies with $\mathrm{log}{M}_{* }/{M}_{\odot }> 10.75$ based on the Galaxy Mass and Assembly (GAMA) survey and measure their total luminosities and g - r colors. We then compare our measurements to various established methods applied to imaging from the Sloan Digital Sky Survey (SDSS), focusing on those favored by the GAMA survey. In general, we find that galaxies are brighter in the r band by an average of ~0.05 mag and bluer in g - r colors by ~0.06 mag compared to the GAMA measurements. These two differences have opposite effects on the stellar-mass estimates. The total luminosities are larger by 5% but the mass-to-light ratios are lower by ~10%. The combined effect is that the stellar-mass estimate of massive galaxies decreases by 7%. This, in turn, implies a small change in the number density of massive galaxies: =30% at $\mathrm{log}{M}_{* }/{M}_{\odot }\geqslant 11$ .
