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

Kennedy, R and Bamford, SP and Häußler, B and Baldry, IK and Bremer, M and Brough, S and Brown, MJI and Driver, S and Duncan, K and Graham, AW and Holwerda, BW and Hopkins, AM and Kelvin, LS and Lange, R and Phillipps, S and Vika, M and Vulcani, B (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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Abstract

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 behavior of single-S\'ersic structural measurements. We denote the variation in single-S\'ersic index with wavelength as $\mathcal{N}$, likewise for effective radius we use $\mathcal{R}$. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of $\mathcal{N}$. The increase in S\'ersic 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 $\mathcal{R}$ ($<$ 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 is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record MNRAS (August 21, 2016) 460 (4): 3458-3471. doi: 10.1093/mnras/stw1176 is available online at:http://dx.doi.org/10.1093/mnras/stw1176
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 20 May 2016 10:58
Last Modified: 23 Sep 2016 10:53
DOI or Identification number: 10.1093/mnras/stw1176
URI: http://researchonline.ljmu.ac.uk/id/eprint/3638

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