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Publication - Mr Tom Kettlety

    Galaxy and mass assembly (GAMA)

    The consistency of GAMA and WISE derived mass-to-light ratios


    Kettlety, T, Hesling, J, Phillipps, S, Bremer, M, Cluver, M, Taylor, E, Bland-Hawthorn, J, Brough, S, De Propris, R, Driver, S, Holwerda, B, Kelvin, L, Sutherland, W & Wright, A, 2018, ‘Galaxy and mass assembly (GAMA): The consistency of GAMA and WISE derived mass-to-light ratios’. Monthly Notices of the Royal Astronomical Society, vol 473., pp. 776-783


    Recent work has suggested that mid-IR wavelengths are optimal for estimating
    the mass-to-light ratios of stellar populations and hence the stellar masses of
    galaxies. We compare stellar masses deduced from spectral energy distribution
    (SED) models, fitted to multi-wavelength optical-NIR photometry, to
    luminosities derived from {\it WISE} photometry in the W1 and W2 bands at
    3.6 and 4.5μm for non-star forming galaxies. The SED derived masses for a
    carefully selected sample of low redshift (z≤0.15) passive galaxies agree
    with the prediction from stellar population synthesis models that M∗/LW1≃0.6 for all such galaxies, independent of other stellar population
    parameters. The small scatter between masses predicted from the optical SED and
    from the {\it WISE} measurements implies that random errors (as opposed to
    systematic ones such as the use of different IMFs) are smaller than previous,
    deliberately conservative, estimates for the SED fits. This test is subtly
    different from simultaneously fitting at a wide range of optical and mid-IR
    wavelengths, which may just generate a compromise fit: we are directly checking
    that the best fit model to the optical data generates an SED whose M∗/LW1
    is also consistent with separate mid-IR data. We confirm that for passive low
    redshift galaxies a fixed M∗/LW1=0.65 can generate masses at least as
    accurate as those obtained from more complex methods. Going beyond the mean
    value, in agreement with expectations from the models, we see a modest change
    in M∗/LW1 with SED fitted stellar population age but an insignificant one
    with metallicity.

    Full details in the University publications repository