Galaxy And Mass Assembly (GAMA): bulge-disc decomposition of KiDS data in the nearby Universe

Sarah Casura, Jochen Liske, Aaron S. G. Robotham, Sarah Brough, Simon P. Driver, Alister W. Graham, Boris Haeussler, Benne W. Holwerda, Andrew M. Hopkins, Lee S. Kelvin, Amanda J. Moffett, Dan S. Taranu, Edward N. Taylor

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)
33 Downloads (Pure)


We derive single Sersic fits and bulge-disc decompositions for 13 096 galaxies at redshifts z < 0.08 in the GAMA II equatorial survey regions in the Kilo-Degree Survey (KiDS) g, r, and i bands. The surface brightness fitting is performed using the Bayesian two-dimensional profile fitting code PROFIT. We fit three models to each galaxy in each band independently with a fully automated Markov chain Monte Carlo analysis: a single Sdrsic model, a Sdrsic plus exponential and a point source plus exponential. After fitting the galaxies, we perform model selection and flag galaxies for which none of our models are appropriate (mainly mergers/Irregular galaxies). The fit quality is assessed by visual inspections, comparison to previous works, comparison of independent fits of galaxies in the overlap regions between KiDS tiles and bespoke simulations. The latter two are also used for a detailed investigation of systematic error sources. We find that our fit results are robust across various galaxy types and image qualities with minimal biases. Errors given by the MCMC underestimate the true errors typically by factors 2-3. Automated model selection criteria are accurate to > 90 per cent as calibrated by visual inspection of a subsample of galaxies. We also present g-r component colours and the corresponding colour-magnitude diagram, consistent with previous works despite our increased fit flexibility. Such reliable structural parameters for the components of a diverse sample of galaxies across multiple bands will be integral to various studies of galaxy properties and evolution. All results are integrated into the GAMA database.
Original languageEnglish
Pages (from-to)942-974
Number of pages33
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 1 Oct 2022


Dive into the research topics of 'Galaxy And Mass Assembly (GAMA): bulge-disc decomposition of KiDS data in the nearby Universe'. Together they form a unique fingerprint.

Cite this