Galaxy And Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies

Luke J M Davies, Aaron S G Robotham, Simon P Driver, Mehmet Alpaslan, Ivan K Baldry, Jonathan Bland-Hawthorn, Sarah Brough, Michael J I Brown, Michelle E Cluver, Michael John Drinkwater, Caroline Foster, Meiert W Grootes, Iraklis S Konstantopoulos, Maritza Arlene Lara-Lopez, Angel R Lopez-Sanchez, Jonathan Loveday, Martin John Meyer, Amanda J Moffett, Peder Norberg, Matthew S OwersCristina Carmen Popescu, Roberto De Propris, Rob Sharp, Richard J Tuffs, Lingyu Wang, Stephen M Wilkins, Loretta Dunne, Nathan Bourne, Matthew Wilson L Smith

Research output: Contribution to journalArticleResearchpeer-review

57 Citations (Scopus)


The modification of star formation (SF) in galaxy interactions is a complex process, with SF observed to be both enhanced in major mergers and suppressed in minor pair interactions. Such changes likely to arise on short time-scales and be directly related to the galaxy-galaxy interaction time. Here we investigate the link between dynamical phase and direct measures of SF on different time-scales for pair galaxies, targeting numerous star- formation rate (SFR) indicators and comparing to pair separation, individual galaxy mass and pair mass ratio. We split our sample into the higher (primary) and lower (secondary) mass galaxies in each pair and find that SF is indeed enhanced in all primary galaxies but suppressed in secondaries of minor mergers. We find that changes in SF of primaries are consistent in both major and minor mergers, suggesting that SF in the more massive galaxy is agnostic to pair mass ratio. We also find that SF is enhanced/suppressed more strongly for short-duration SFR indicators (e.g. Ha), highlighting recent changes to SF in these galaxies, which are likely to be induced by the interaction. We propose a scenario where the lower mass galaxy has its SF suppressed by gas heating or stripping, while the higher mass galaxy has its SF enhanced, potentially by tidal gas turbulence and shocks. This is consistent with the seemingly contradictory observations for both SF suppression and enhancement in close pairs.
Original languageEnglish
Pages (from-to)616-636
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 2015


  • Galaxies: evolution
  • Galaxies: interactions
  • Galaxies: star formation

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