Galaxy and Mass Assembly (GAMA): The GAMA galaxy group catalogue (G3Cv1)

A Robotham, Peder Norberg, Simon Driver, Ivan Baldry, Steven Bamford, Andrew Hopkins, J Liske, J Loveday, Alexander Merson, John Peacock, Sarah Brough, Ewan Cameron, Christopher Conselice, Scott Croom, C Frenk, Madusha Gunawardhana, D Hill, David Jones, L Kelvin, K KuijkenR Nichol, H Parkinson, Kevin Pimbblet, Steven Phillipps, Cristina Popescu, Matthew Prescott, Robert Sharp, W Sutherland, Edward Taylor, D Thomas, R Tuffs, E van Kampen, Dinuka Wijesinghe

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    Using the complete Galaxy and Mass Assembly I (GAMA-I) survey covering a??142deg2 torAB= 19.4, of which a??47deg2 is torAB= 19.8, we create the GAMA-I galaxy group catalogue (G3Cv1), generated using a friends-of-friends (FoF) based grouping algorithm. Our algorithm has been tested extensively on one family of mock GAMA lightcones, constructed from I? cold dark matterN-body simulations populated with semi-analytic galaxies. Recovered group properties are robust to the effects of interlopers and are median unbiased in the most important respects. G3Cv1 contains 14388 galaxy groups (with multiplicity a?Y2), including 44186 galaxies out of a possible 110192 galaxies, implying a??40 per cent of all galaxies are assigned to a group. The similarities of the mock group catalogues and G3Cv1 are multiple: global characteristics are in general well recovered. However, we do find a noticeable deficit in the number of high multiplicity groups in GAMA compared to the mocks. Additionally, despite exceptionally good local spatial completeness, G3Cv1 contains significantly fewer compact groups with five or more members, this effect becoming most evident for high multiplicity systems. These two differences are most likely due to limitations in the physics included of the current GAMA lightcone mock. Further studies using a variety of galaxy formation models are required to confirm their exact origin. The G3Cv1 catalogue will be made publicly available as and when the relevant GAMA redshifts are made available at
    Original languageEnglish
    Pages (from-to)2640 - 2668
    Number of pages29
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number4
    Publication statusPublished - 2011

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