Data from: Galaxy And Mass Assembly (GAMA): Defining passive galaxy samples and searching for the UV upturn

  • Steven Phillipps (Creator)
  • S. S. Ali (Creator)
  • Malcom N. Bremer (Creator)
  • Roberto De Propris (Creator)
  • Anne E. Sansom (Creator)
  • Michelle E. Cluver (Creator)
  • Mehmet Alpaslan (Creator)
  • Sarah Brough (Creator)
  • Michael J. I. Brown (Creator)
  • Luke Davies (Creator)
  • Simon Driver (Creator)
  • Meiert W. Grootes (Creator)
  • Benne W. Holwerda (Creator)
  • Andrew M. Hopkins (Creator)
  • P. A. James (Creator)
  • Kevin Pimbblet (Creator)
  • Aaron Robotham (Creator)
  • E. N. Taylor (Creator)
  • Lingyu Wang (Creator)



We use data from the GAMA and GALEX surveys to demonstrate that the UV upturn, an unexpected excess of ultraviolet flux from a hot stellar component, seen in the spectra of many early-type galaxies, arises from processes internal to individual galaxies with no measurable influence from the galaxies' larger environment. We first define a clean sample of passive galaxies without a significant contribution to their UV flux from low-level star formation. We confirm that galaxies with the optical colours of red sequence galaxies often have signs of residual star formation, which, without other information, would prevent a convincing demonstration of the presence of UV upturns. However, by including (NUV−u) and WISE (W2-W3) colours, and FUV data where it exists, we can convincingly constrain samples to be composed of non-star-forming objects. Using such a sample, we examine GALEX photometry of low-redshift GAMA galaxies in a range of low-density environments, from groups to the general field, searching for UV upturns. We find a wide range of (NUV−r) colours, entirely consistent with the range seen - and attributed to the UV upturn - in low-redshift red sequence cluster galaxies. The range of colours is independent of group multiplicity or velocity dispersion, with isolated passive galaxies just as likely to have blue UV-to-optical colours, implying significant upturn components, as those in richer groups and in the previous data on clusters. This is supported by equivalent results for (FUV−r) colours which are clear indicators of upturn components.
Date made availableFeb 2020
PublisherSAO/NASA Astrophysics Data System (ADS)


  • galaxies: evolution
  • galaxies: star formation
  • galaxies: stellar content
  • Astrophysics - Astrophysics of Galaxies

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