Publication details for Prof Richard BowerNorris, M. A., Van de Ven, G., Schinnerer, E., Crain, R. A., Meidt, S., Groves, B., Bower, R. G., Furlong, M., Schaller, M., Schaye, J. & Theuns, T. (2016). Being WISE II: Reducing the Influence of Star formation History on the Mass-to-Light Ratio of Quiescent Galaxies. Astrophysical Journal 832(2): 198.
- Publication type: Journal Article
- ISSN/ISBN: 0004-637X, 1538-4357
- DOI: 10.3847/0004-637X/832/2/198
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
Stellar population synthesis models can now reproduce the photometry of old stellar systems (age > 2 Gyr) in the near-infrared (NIR) bands at 3.4 and 4.6μm (WISE W1 & W2 or IRAC 1 & 2). In this paper we derive stellar mass-to-light ratios for these and optical bands, and confirm that the NIR M/L shows dramatically reduced sensitivity to both age and metallicity compared to optical bands, and further, that this behavior leads to significantly more robust stellar masses for quiescent galaxies with [Fe/H] > -0.5 regardless of star formation history (SFH). We then use realistic early-type galaxy SFHs and metallicity distributions from the EAGLE simulations of galaxy formation to investigate two methods to determine the appropriate M/L for a galaxy: 1) We show that the uncertainties introduced by an unknown SFH can be largely removed using a spectroscopically inferred luminosity-weighted age and metallicity for the population to select the appropriate single stellar population (SSP) equivalent M/L. Using this method, the maximum systematic error due to SFH on the M/L of an early-type galaxy is < 4% at 3.4 μm and typical uncertainties due to errors in the age and metallicity create scatter of ≲13%. The equivalent values for optical bands are more than 2-3 times greater, even before considering uncertainties associated with internal dust extinction. 2) We demonstrate that if the EAGLE SFHs and metallicities accurately reproduce the true properties of early-type galaxies, the use of an iterative approach to select a mass dependent M/L can provide even more accurate stellar masses for early-type galaxies, with typical uncertainties < 9%.