1. Lucatelli, G. and Ferrari, F. Galaxy structural analysis with the curvature of the brightness profile. Monthly Notices of the Royal Astronomical Society,
Volume 489, Issue 1, October 2019, Pages 1161–1180,
In this work we introduce the curvature of a galaxy brightness profile to
non-parametrically identify its structural subcomponents. Bulges, bars, disks,
lens, rings, spiral arms and so on, are a key to understanding the formation and
evolutionary paths the galaxy undertook. Their identification is also crucial for the
morphological classification of galaxies. We measure and analyse in detail the
curvature of $16$ galaxies with varied morphology. High (low) steepness
profiles show high (low) absolute curvature measures.
Transitions between components present high values of the curvature.
With this new tool we identify patterns that characterise bulges (pseudo or
classic), disks, bars, rings, spiral arms. The procedure can be automated in
a future study to deal with large datasets and identify galaxy components
automatically, or to provide a reliable starting point for traditional multi
components modelling of galaxy light distribution. For a complementary
study, which leaded us to introduce the curvature, we investigate
the behaviour of single-Sérsic fits (e.g. single Sérsic index $n$) is and
concentration index $C$ for multicomponent galaxies. We have obtained that these
galaxies have systematically high values of $n$ and $C$ comparable to the ones
measured in single component galaxies, thus resulting in misclassification of them.