Oral comunication
S. N. Reis
Abstract
The most massive (M* ≥ 1011 M⊙) galaxies in the local Universe are characterized by having a bulge-dominated morphology and old stellar populations, in addition to be confined to a tight mass-size relation. Identifying their main components can provide insights into their formation mechanisms and subsequent mass assembly. Taking advantage of HST CANDELS data, we analyze the lowest redshift (z < 0.5) massive galaxies in the H and I-band in order to disentangle their structural constituents and study possible faint non-axis-symmetric features. We find that the Sérsic index does not offer a good proxy for the morphological type for our sample of massive galaxies. Our derived multi-component effective radii give a better description of the size of our sample galaxies than those inferred from single Sérsic models with GALFIT. Interestingly for our small albeit interesting sample, two of the late-type galaxies in our sample are by ~2 sigma smaller than expected from the local mass-size relation. For most of our sample galaxies, both single and multi-component Sérsic models with GALFIT show substantial systematic deviations from the observed surface brightness profiles in the outskirts. These residuals may be partly due to the stellar haloes of these objects or could arise from conceptual shortcomings of parametric 2D image decomposition tools. A problematic consequence is that they propagate into differences of >1 mag between model and observed radial I-H color profiles. This is a significant obstacle to the exploration of the structural evolution of galaxies that calls for a critical assessment and refinement of existing surface photometry techniques.
XXIX Encontro Nacional de Estudantes de Astronomia
Lisboa, Portugal
2019 September
