Galaxy And Mass Assembly (GAMA): the wavelength-dependent sizes and
  profiles of galaxies revealed by MegaMorph
  We investigate the relationship between colour and structure within galaxies
using a large, volume-limited sample of bright, low-redshift galaxies with
optical to near-infrared imaging from the GAMA survey. We fit single-component,
wavelength-dependent, elliptical Sersic models to all passbands simultaneously,
using software developed by the MegaMorph project. Dividing our sample by
Sersic index and colour, the recovered wavelength variations in effective
radius (R_e) and Sersic index (n) reveal the internal structure, and hence
formation history, of different types of galaxies. All these trends depend on
n; some have an additional dependence on galaxy colour. Late-type galaxies (n_r
< 2.5) show a dramatic increase in Sersic index with wavelength. This might be
a result of their two-component (bulge-disk) nature, though stellar population
gradients within each component and dust attenuation are likely to play a role.
All galaxies show a substantial decrease in R_e with wavelength. This is
strongest for early-types (n_r > 2.5), even though they maintain constant n
with wavelength, revealing that ellipticals are a superimposition of different
stellar populations associated with multiple collapse and merging events.
Processes leading to structures with larger R_e must be associated with lower
metallicity or younger stellar populations. This appears to rule out the
formation of young cores through dissipative gas accretion as an important
mechanism in the recent lives of luminous elliptical galaxies.
