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The SAMI Galaxy Survey: Revisitng galaxy classification through high-order stellar kinematics

van de Sande, J; Bland-Hawthorn, Joss; Fogarty, Lisa M R; Cortese, L; D'Eugenio, Francesco; Croom, Scott M; Scott, Nicholas; Allen, James T; Brough, Sarah; Bryant, Julia J.; Cecil, Gerald; Colless, Matthew; Groves, Brent Allan; Ho, I-Ting; Leslie, Sarah; Medling, Anne; Sharp, Rob; Sweet, Sarah

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Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h3 (~skewness) and h4 (~kurtosis) in galaxies to their cosmological assembly history. Here, we assess these results by measuring the stellar kinematics on a sample of 315 galaxies, without a morphological selection, using two-dimensional integral field data from the SAMI Galaxy Survey. Proxies for the spin parameter (${\lambda }_{{R}_{{\rm{e}}}}$) and...[Show more]

dc.contributor.authorvan de Sande, J
dc.contributor.authorBland-Hawthorn, Joss
dc.contributor.authorFogarty, Lisa M R
dc.contributor.authorCortese, L
dc.contributor.authorD'Eugenio, Francesco
dc.contributor.authorCroom, Scott M
dc.contributor.authorScott, Nicholas
dc.contributor.authorAllen, James T
dc.contributor.authorBrough, Sarah
dc.contributor.authorBryant, Julia J.
dc.contributor.authorCecil, Gerald
dc.contributor.authorColless, Matthew
dc.contributor.authorGroves, Brent Allan
dc.contributor.authorHo, I-Ting
dc.contributor.authorLeslie, Sarah
dc.contributor.authorMedling, Anne
dc.contributor.authorSharp, Rob
dc.contributor.authorSweet, Sarah
dc.date.accessioned2020-12-20T20:58:12Z
dc.date.available2020-12-20T20:58:12Z
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1885/218515
dc.description.abstractRecent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h3 (~skewness) and h4 (~kurtosis) in galaxies to their cosmological assembly history. Here, we assess these results by measuring the stellar kinematics on a sample of 315 galaxies, without a morphological selection, using two-dimensional integral field data from the SAMI Galaxy Survey. Proxies for the spin parameter (${\lambda }_{{R}_{{\rm{e}}}}$) and ellipticity (${\epsilon }_{{\rm{e}}}$) are used to separate fast and slow rotators; there exists a good correspondence to regular and non-regular rotators, respectively, as also seen in earlier studies. We confirm that regular rotators show a strong h3 versus $V/\sigma $ anti-correlation, whereas quasi-regular and non-regular rotators show a more vertical relation in h3 and $V/\sigma $. Motivated by recent cosmological simulations, we develop an alternative approach to kinematically classify galaxies from their individual h3 versus $V/\sigma $ signatures. Within the SAMI Galaxy Survey, we identify five classes of high-order stellar kinematic signatures using Gaussian mixture models. Class 1 corresponds to slow rotators, whereas Classes 2–5 correspond to fast rotators. We find that galaxies with similar ${\lambda }_{{R}_{{\rm{e}}}}\mbox{--}{\epsilon }_{{\rm{e}}}$ values can show distinctly different ${h}_{3}\mbox{--}V/\sigma $ signatures. Class 5 objects are previously unidentified fast rotators that show a weak h3 versus $V/\sigma $ anti-correlation. From simulations, these objects are predicted to be disk-less galaxies formed by gas-poor mergers. From morphological examination, however, there is evidence for large stellar disks. Instead, Class 5 objects are more likely disturbed galaxies, have counter-rotating bulges, or bars in edge-on galaxies. Finally, we interpret the strong anti-correlation in h3 versus $V/\sigma $ as evidence for disks in most fast rotators, suggesting a dearth of gas-poor mergers among fast rotators.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherIOP Publishing
dc.sourceThe Astrophysical Journal
dc.titleThe SAMI Galaxy Survey: Revisitng galaxy classification through high-order stellar kinematics
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume835
dc.date.issued2017
local.identifier.absfor020104 - Galactic Astronomy
local.identifier.ariespublicationa383154xPUB6400
local.type.statusPublished Version
local.contributor.affiliationvan de Sande, J, University of Sydney
local.contributor.affiliationBland-Hawthorn, Joss, University of Sydney
local.contributor.affiliationFogarty, Lisa M R, University of Sydney
local.contributor.affiliationCortese, L, University of Western Australia
local.contributor.affiliationD'Eugenio, Francesco, College of Science, ANU
local.contributor.affiliationCroom, Scott M, University of Sydney
local.contributor.affiliationScott, Nicholas, University of Sydney
local.contributor.affiliationAllen, James T, University of Sydney
local.contributor.affiliationBrough, Sarah, Australian Astronomical Observatory
local.contributor.affiliationBryant, Julia J., The University of Sydney, School of Physics
local.contributor.affiliationCecil, Gerald, University of North Carolina
local.contributor.affiliationColless, Matthew, College of Science, ANU
local.contributor.affiliationGroves, Brent Allan, College of Science, ANU
local.contributor.affiliationHo, I-Ting, College of Science, ANU
local.contributor.affiliationLeslie, Sarah, College of Science, ANU
local.contributor.affiliationMedling, Anne, College of Science, ANU
local.contributor.affiliationSharp, Rob, College of Science, ANU
local.contributor.affiliationSweet, Sarah, College of Science, ANU
local.bibliographicCitation.issue1
local.identifier.doi10.3847/1538-4357/835/1/104
dc.date.updated2020-11-23T11:20:23Z
local.identifier.scopusID2-s2.0-85011279106
local.identifier.thomsonID000393455400104
CollectionsANU Research Publications

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