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

Davies, LJM and Robotham, ASG and Driver, SP and Alpaslan, M and Baldry, IK and Bland-Hawthorn, J and Brough, S and Brown, MJI and Cluver, ME and Drinkwater, MJ and Foster, C and Grootes, MW and Konstantopoulos, IS and Lara-Lopez, MA and Lopez-Sanchez, AR and Loveday, J and Meyer, MJ and Moffett, AJ and Norberg, P and Owers, MS and Popescu, CC and Propris, RD and Sharp, R and Tuffs, RJ and Wang, L and Wilkins, SM and Bourne, LDN and Smith, MWL (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). pp. 616-636. ISSN 0035-8711

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Abstract

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 timescales 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 timescales 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 is 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-time duration SFR indicators (e.g. H-alpha), 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.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record 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., Konstantopoulous, I, S., Lara-Lopez, M.A., Lopez-Sanchez, A.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. (2015) Galaxy And Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies is available online at: http://dx.doi.org/10.1093/mnras/stv1241
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 27 Jul 2015 15:02
Last Modified: 27 Jul 2015 15:02
DOI or Identification number: /10.1093/mnras/stv1241
URI: http://researchonline.ljmu.ac.uk/id/eprint/1689

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