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Astrophysically motivated bulge-disc decompositions of Sloan Digital Sky Survey galaxies

Author(s): Lackner, CN; Gunn, James E

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Abstract: We present a set of bulge-disc decompositions for a sample of 71 825 Sloan Digital Sky Survey (SDSS) main-sample galaxies in the redshift range 0.003 < z < 0.05. We have fitted each galaxy with either a de Vaucouleurs (classical) or an exponential (pseudo-) bulge and an exponential disc. Two-dimensional Sersic fits are performed when the two-component fits are not statistically significant or when the fits are poor, even in the presence of high signal-to-noise ratio (S/N). We study the robustness of our two-component fits by studying a bright subsample of galaxies and we study the systematics of these fits with decreasing resolution and S/N. Only 30 per cent of our sample have been fitted with two-component fits in which both components are non-zero. The g-r and g-i colours of each component for the two-component models are determined using linear templates derived from the r-band model. We attempt a physical classification of types of fits into disc galaxies, pseudo-bulges, classical bulges and ellipticals. Our classification of galaxies agrees well with previous large bulge plus disc (B+D) decomposed samples. Using our galaxy classifications, we find that Petrosian concentration is a good indicator of bulge-to-total ratio, while overall Sersic index is not. Additionally, we find that the majority of green valley galaxies are bulge+disc galaxies. Furthermore, in the transition from green to red B+D galaxies, the total galaxy colour is most strongly correlated with the disc colour.
Publication Date: Apr-2012
Citation: Lackner, CN, Gunn, JE. (2012). Astrophysically motivated bulge-disc decompositions of Sloan Digital Sky Survey galaxies. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 421 (2277 - 2302. doi:10.1111/j.1365-2966.2012.20450.x
DOI: doi:10.1111/j.1365-2966.2012.20450.x
ISSN: 0035-8711
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Pages: 2277 - 2302
Type of Material: Journal Article
Version: Author's manuscript

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