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

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

Abstract

We present the ∼800 star formation rate maps for the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey based on H α 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, [N II]/H α, [S II]/H α, and [O I]/H α line ratios. Using these maps, we examine the global and resolved star-forming 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.

Additional Information

© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2018 January 10. Received 2018 January 10; in original form 2017 May 19. We thank the referee for their thoughtful suggestions to improve the manuscript. Support for A.M.M. is provided by National Aeronautics and Space Administration (NASA) through Hubble Fellowship grant #HST-HF2-51377 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. S.M.C. acknowledges the support of an Australian Research Council Future Fellowship (FT100100457). S.B. acknowledges funding support from the Australian Research Council through a Future Fellowship (FT140101166). B.C. is the recipient of an Australian Research Council Future Fellowship (FT120100660). C.F. gratefully acknowledges funding provided by the Australian Research Council's Discovery Projects (grants DP150104329 and DP170100603). M.S.O. acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140100255). R.Mc.D. is the recipient of an Australian Research Council Future Fellowship (project number FT150100333). N.S. acknowledges support of a University of Sydney Postdoctoral Research Fellowship. J.v.d.S. is funded under Bland-Hawthorn's Australian Research Council (ARC) Laureate Fellowship (FL140100278). The SAMI Galaxy Survey is based on observations made at the Anglo-Australian Telescope. The SAMI was developed jointly by the University of Sydney and the Australian Astronomical Observatory. The SAMI input catalogue is based on data taken from the Sloan Digital Sky Survey, the GAMA Survey, and the VST ATLAS Survey. The SAMI Galaxy Survey is funded by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and other participating institutions. The SAMI Galaxy Survey website is http://sami-survey.org/. GAMA is a joint European-Australasian project based around a spectroscopic campaign using the Anglo-Australian Telescope. The GAMA input catalogue is based on data taken from the Sloan Digital Sky Survey and the UKIRT Infrared Deep Sky Survey. Complementary imaging of the GAMA regions is being obtained by a number of independent survey programmes including GALEX MIS, VST KiDS, VISTA VIKING, WISE, Herschel-ATLAS, GMRT, and ASKAP providing ultraviolet to radio coverage. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO, and the participating institutions. The GAMA website is http://www.gama-survey.org/. This work is based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 179.A-2004 and 177.A-3016.

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