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Taking advantage of HST CANDELS data, we analyze the lowest redshift (z<0.5)massive galaxies in order to disentangle their structural constituents andstudy possible faint non-axis-symmetric features. Due to the excellent HSTspatial resolution for intermediate-z objects, they are hard to model by purelyautomatic parametric fitting algorithms. We performed careful single and doubleS\'ersic fits to their galaxy surface brightness profiles. We also compare themodel color profiles with the observed ones and also derive multi-componentglobal effective radii attempting to obtain a better interpretation of themass-size relation. Additionally, we test the robustness of our measuredstructural parameters via simulations. We find that the S\'ersic index does notoffer a good proxy for the visual morphological type for our sample of massivegalaxies. Our derived multi-component effective radii give a better descriptionof the size of our sample galaxies than those inferred from single S\'ersicmodels with GALFIT. Our galaxy population lays on the scatter of the localmass-size relation, indicating that these massive galaxies do not experience asignificant growth in size since z~0.5. Interestingly the few outliers arelate-type galaxies, indicating that spheroids must reach the local mass-sizerelation earlier. For most of our sample galaxies, both single andmulti-component S\'ersic models with GALFIT show substantial systematicdeviations from the observed SBPs in the outskirts. These residuals may bepartly due to several factors, namely a non-optimal data reduction for lowsurface brightness features, the existence of prominent stellar haloes formassive galaxies and could also arise from conceptual shortcomings ofparametric 2D image decomposition tools. They consequently propagate intogalaxy color profiles.

Structural analysis of massive galaxies using HST deep imaging at z < 0.5