Color gradients reflect an inside-out growth in early-type galaxies of
  the cluster MACS J1206.2-0847
  We use color gradients to explore the evolution of early-type galaxies in the
core of the massive galaxy cluster MACS J1206.2-0847 at z = 0.44. We used data
from the CLASH and CLASH-VLT surveys to perform multiwavelength optimized model
fitting using Galapagos-2 from the MegaMorph project to measure their
photometric parameters. We derive color gradients for $g_{475} - I_{814}$,
$r_{625} - Y_{105}$, $I_{814} - H_{160}$ , and $Y_{105} - H_{160}$ at radii
ranging between 0.1 - 2 $r_e$ for 79 early-type cluster galaxies. From
synthetic spectral models that use simple star formation recipes, we inferred
ages and metallicities of the stellar population at different locations within
each galaxy and characterized their influence on the radial color trends. We
measure that galaxy sizes are $\sim$ 25% smaller in the red $H_{160}$ filter
than in the blue $r_{625}$ filter but maintain a constant (within 3$\sigma$)
S\'{e}rsic index $n$ with wavelength. We find negative color gradients in all
colors with slopes ranging between -0.07 and -0.17 mag dex$^{-1}$ and with no
obvious dependence on total magnitude, stellar mass, or location inside the
cluster core. We explain the observed radial trends of color gradients as a
result of the ages and metallicities of the respective stellar populations. Red
galaxy cores are typically $\sim$ 3 Gyr older and more enriched in metals than
the galaxy outskirts, which are of solar metallicity.
