The SAMI Galaxy Survey: spatially resolving the main sequence of star formation

Anne M. Medling*, Luca Cortese, Scott M. Croom, Andrew W. Green, Brent Groves, Elise Hampton, I-Ting Ho, Luke J.M. Davies, Lisa J. Kewley, Amanda J. Moffett, Adam L. Schaefer, Edward Taylor, Tayyaba Zafar, Kenji Bekki, Joss Bland-Hawthorn, Jessica V. Bloom, Sarah Brough, Julia J. Bryant, Barbara Catinella, Gerald CecilMatthew Colless, Warrick J. Couch, Michael J. Drinkwater, Simon P. Driver, Christoph Federrath, Caroline Foster, Gregory Goldstein, Michael Goodwin, Andrew Hopkins, J. S. Lawrence, Sarah K. Leslie, Geraint F. Lewis, Nuria P.F. Lorente, Matt S. Owers, Richard McDermid, Samuel N. Richards, Robert Sharp, Nicholas Scott, Sarah M. Sweet, Dan S. Taranu, Edoardo Tescari, Chiara Tonini, Jesse van de Sande, C. Jakob Walcher, Angus Wright

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    80 Citations (Scopus)


    We present the ~800 star formation rate maps for the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey based on Ha emission maps, corrected for dust attenuation via the Balmer decrement, that are included in the SAMI Public Data Release 1. We mask out spaxels contaminated by non-stellar emission using the [O III]/H β, [NII]/H α, [S II]/H α, and [O I]/H α line ratios. Using thesemaps, we examine the global and resolved starforming main sequences of SAMI galaxies as a function of morphology, environmental density, and stellar mass. Galaxies further below the star-forming main sequence are more likely to have flatter star formation profiles. Early-type galaxies split into two populations with similar stellar masses and central stellar mass surface densities. The main-sequence population has centrally concentrated star formation similar to late-type galaxies, while galaxies > 3σ below the main sequence show significantly reduced star formation most strikingly in the nuclear regions. The split populations support a two-step quenching mechanism, wherein halo mass first cuts off the gas supply and remaining gas continues to form stars until the local stellar mass surface density can stabilize the reduced remaining fuel against further star formation. Across all morphologies, galaxies in denser environments show a decreased specific star formation rate from the outside in, supporting an environmental cause for quenching, such as ram-pressure stripping or galaxy interactions.

    Original languageEnglish
    Pages (from-to)5194-5214
    Number of pages21
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number4
    Publication statusPublished - 1 Apr 2018


    • Galaxies: evolution
    • Galaxies: star formation
    • Surveys


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