Galaxy And Mass Assembly (GAMA): Galaxy colour gradients versus colour, structure and luminosity

Abstract

Using single-component fits to SDSS/UKIDSS images of galaxies in the G09 region of the GAMA survey we study radial colour gradients across the galaxy population. We use the multiwavelength information provided by MegaMorph analysis of galaxy light profiles to calculate intrinsic colour gradients, and divide into six subsamples split by overall Sérsic index ($n$) and galaxy colour. We find a bimodality in the colour gradients of high- and low-$n$ galaxies in all wavebands, which varies with overall galaxy luminosity. Global trends in colour gradients therefore result from combining the contrasting behaviour of a number of different galaxy populations. The ubiquity of strong negative colour gradients supports the picture of inside-out growth through gas accretion for blue, low-$n$ galaxies, and through dry minor mergers for red, high-$n$ galaxies. An exception is the blue high-n population, with properties indicative of dissipative major mergers.

4 pages, 2 figures, accepted by A&A

References in corpus (4)

• Stellar Population gradients in galaxy discs from the CALIFA survey
• Galaxy And Mass Assembly (GAMA): the wavelength-dependent sizes and profiles of galaxies revealed by MegaMorph
• The GALEX Arecibo SDSS survey: III. Evidence for the Inside-Out Formation of Galactic Disks
• Evolution of the Major Merger Galaxy Pair Fraction at z < 1

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