Galaxy And Mass Assembly (GAMA): understanding the wavelength dependence of galaxy structure with bulge-disc decompositions

Kennedy, Rebecca and Bamford, Steven P. and Häußler, Boris and Baldry, Ivan and Bremer, Malcolm and Brough, Sarah and Brown, Michael J.I. and Driver, Simon and Duncan, Kenneth and Graham, Alister W. and Holwerda, Benne W. and Hopkins, Andrew M. and Kelvin, Lee S. and Lange, Rebecca and Phillipps, Steven and Vika, Marina and Vulcani, Benedetta (2016) Galaxy And Mass Assembly (GAMA): understanding the wavelength dependence of galaxy structure with bulge-disc decompositions. Monthly Notices of the Royal Astronomical Society, 460 (4). pp. 3458-3471. ISSN 1365-2966

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With a large sample of bright, low-redshift galaxies with optical–near-IR imaging from the GAMA survey we use bulge-disc decompositions to understand the wavelength-dependent behaviour of single-Sersic structural measurements. We denote the variation in single-Sersic index with wavelength as N, likewise for effective radius we use R. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of N. The increase in Sersic index to longer wavelengths is therefore intrinsic to discs, apparently resulting from radial variations in stellar population and/or dust reddening. Similarly, low values of R (< 1) are found to be ubiquitous, implying an element of universality in galaxy colour gradients. We also study how bulge and disc colour distributions vary with galaxy type. We find that, rather than all bulges being red and all discs being blue in absolute terms, both components become redder for galaxies with redder total colours. We even observe that bulges in bluer galaxies are typically bluer than discs in red galaxies, and that bulges and discs are closer in colour for fainter galaxies. Trends in total colour are therefore not solely due to the colour or flux dominance of the bulge or disc.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: galaxies: formation, galaxies: fundamental parameters, galaxies: general, galaxies: structure
Schools/Departments: University of Nottingham UK Campus > Faculty of Science > School of Physics and Astronomy
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Depositing User: Eprints, Support
Date Deposited: 13 Jul 2016 10:38
Last Modified: 14 Sep 2016 23:31

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