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

Davies, L.J.M.; Robotham, A.S.G.; Driver, S.P.; Alpaslan, M.; Baldry, I.K.; Bland-Hawthorn, J.; Brough, S.; Brown, M.J.I.; Cluver, M.E.; Drinkwater, M.J.; Foster, C.; Grootes, M.W.; Konstantopoulos, I.S.; Lara-López, M.A.; López-Sánchez, Á.R.; Loveday, J.; Meyer, M.J.; Moffett, A.J.; Norberg, P.; Owers, M.S.; Popescu, C.C.; De Propris, R.; Sharp, R.; Tuffs, R.J.; Wang, L.; Wilkins, S.M.; Dunne, L.; Bourne, N.; Smith, M.W.L.

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


L.J.M. Davies

A.S.G. Robotham

S.P. Driver

M. Alpaslan

I.K. Baldry

J. Bland-Hawthorn

S. Brough

M.J.I. Brown

M.E. Cluver

M.J. Drinkwater

C. Foster

M.W. Grootes

I.S. Konstantopoulos

M.A. Lara-López

Á.R. López-Sánchez

J. Loveday

M.J. Meyer

A.J. Moffett

M.S. Owers

C.C. Popescu

R. De Propris

R. Sharp

R.J. Tuffs

L. Wang

S.M. Wilkins

L. Dunne

N. Bourne

M.W.L. Smith


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. Hα), 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.


Davies, L., Robotham, A., Driver, S., Alpaslan, M., Baldry, I., Bland-Hawthorn, J., …Smith, M. (2015). Galaxy And Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies. Monthly Notices of the Royal Astronomical Society, 452(1), 616-636.

Journal Article Type Article
Acceptance Date Jun 1, 2015
Publication Date Sep 1, 2015
Deposit Date Feb 3, 2016
Publicly Available Date Feb 11, 2016
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 452
Issue 1
Pages 616-636
Keywords Galaxies: evolution, Galaxies: interactions, Galaxies: star formation.


Published Journal Article (5.3 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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