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The SAMI Galaxy Survey: The Internal Orbital Structure and Mass Distribution of Passive Galaxies from Triaxial Orbit-superposition Schwarzschild Models

cam.issuedOnline2022-05-13
dc.contributor.authorSantucci, G
dc.contributor.authorBrough, S
dc.contributor.authorVan De Sande, J
dc.contributor.authorMcDermid, RM
dc.contributor.authorVan De Ven, G
dc.contributor.authorZhu, L
dc.contributor.authorD'Eugenio, F
dc.contributor.authorBland-Hawthorn, J
dc.contributor.authorBarsanti, S
dc.contributor.authorBryant, JJ
dc.contributor.authorM. Croom, S
dc.contributor.authorDavies, RL
dc.contributor.authorGreen, AW
dc.contributor.authorLawrence, JS
dc.contributor.authorLorente, NPF
dc.contributor.authorOwers, MS
dc.contributor.authorPoci, A
dc.contributor.authorRichards, SN
dc.contributor.authorThater, S
dc.contributor.authorYi, S
dc.contributor.orcidSantucci, G [0000-0003-3283-4686]
dc.contributor.orcidBrough, S [0000-0002-9796-1363]
dc.contributor.orcidVan De Sande, J [0000-0003-2552-0021]
dc.contributor.orcidMcDermid, RM [0000-0002-8175-7229]
dc.contributor.orcidVan De Ven, G [0000-0003-4546-7731]
dc.contributor.orcidZhu, L [0000-0002-8005-0870]
dc.contributor.orcidD'Eugenio, F [0000-0003-2388-8172]
dc.contributor.orcidBland-Hawthorn, J [0000-0001-7516-4016]
dc.contributor.orcidBarsanti, S [0000-0002-9332-5386]
dc.contributor.orcidBryant, JJ [0000-0003-1627-9301]
dc.contributor.orcidM. Croom, S [0000-0003-2880-9197]
dc.contributor.orcidDavies, RL [0000-0001-7897-3812]
dc.contributor.orcidOwers, MS [0000-0002-2879-1663]
dc.contributor.orcidPoci, A [0000-0002-5422-7441]
dc.contributor.orcidThater, S [0000-0003-1820-2041]
dc.contributor.orcidYi, S [0000-0002-4556-2619]
dc.date.accessioned2022-05-13T17:00:11Z
dc.date.available2022-05-13T17:00:11Z
dc.date.issued2022
dc.date.submitted2021-10-20
dc.date.updated2022-05-13T17:00:10Z
dc.description.abstract<jats:title>Abstract</jats:title> <jats:p>Dynamical models are crucial for uncovering the internal dynamics of galaxies; however, most of the results to date assume axisymmetry, which is not representative of a significant fraction of massive galaxies. Here, we build triaxial Schwarzschild orbit-superposition models of galaxies taken from the SAMI Galaxy Survey, in order to reconstruct their inner orbital structure and mass distribution. The sample consists of 161 passive galaxies with total stellar masses in the range 10<jats:sup>9.5</jats:sup>–10<jats:sup>12</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. We find that the changes in internal structures within 1<jats:italic>R</jats:italic> <jats:sub>e</jats:sub> are correlated with the total stellar mass of the individual galaxies. The majority of the galaxies in the sample (73% ± 3%) are oblate, while 19% ± 3% are mildly triaxial and 8% ± 2% have triaxial/prolate shape. Galaxies with <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}{M}_{\star }/{M}_{\odot }\gt 10.50$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>&gt;</mml:mo> <mml:mn>10.50</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5bd5ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> are more likely to be non-oblate. We find a mean dark matter fraction of <jats:italic>f</jats:italic> <jats:sub>DM</jats:sub> = 0.28 ± 0.20, within 1<jats:italic>R</jats:italic> <jats:sub>e</jats:sub>. Galaxies with higher intrinsic ellipticity (flatter) are found to have more negative velocity anisotropy <jats:italic>β</jats:italic> <jats:sub> <jats:italic>r</jats:italic> </jats:sub> (tangential anisotropy). <jats:italic>β</jats:italic> <jats:sub> <jats:italic>r</jats:italic> </jats:sub> also shows an anticorrelation with the edge-on spin parameter <jats:inline-formula> <jats:tex-math> <?CDATA ${\lambda }_{\mathrm{Re},\mathrm{EO}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>λ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Re</mml:mi> <mml:mo>,</mml:mo> <mml:mi>EO</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5bd5ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, so that <jats:italic>β</jats:italic> <jats:sub> <jats:italic>r</jats:italic> </jats:sub> decreases with increasing <jats:inline-formula> <jats:tex-math> <?CDATA ${\lambda }_{\mathrm{Re},\mathrm{EO}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>λ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Re</mml:mi> <mml:mo>,</mml:mo> <mml:mi>EO</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5bd5ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>, reflecting the contribution from disk-like orbits in flat, fast-rotating galaxies. We see evidence of an increasing fraction of hot orbits with increasing stellar mass, while warm and cold orbits show a decreasing trend. We also find that galaxies with different (<jats:italic>V</jats:italic>/<jats:italic>σ</jats:italic> – <jats:italic>h</jats:italic> <jats:sub>3</jats:sub>) kinematic signatures have distinct combinations of orbits. These results are in agreement with a formation scenario in which slow- and fast-rotating galaxies form through two main channels.</jats:p>
dc.identifier.doi10.17863/CAM.84556
dc.identifier.eissn1538-4357
dc.identifier.issn0004-637X
dc.identifier.otherapjac5bd5
dc.identifier.otherac5bd5
dc.identifier.otheraas35564
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/337137
dc.languageen
dc.language.isoeng
dc.publisherAmerican Astronomical Society
dc.publisher.urlhttp://dx.doi.org/10.3847/1538-4357/ac5bd5
dc.subject5109 Space Sciences
dc.subject51 Physical Sciences
dc.titleThe SAMI Galaxy Survey: The Internal Orbital Structure and Mass Distribution of Passive Galaxies from Triaxial Orbit-superposition Schwarzschild Models
dc.typeArticle
dcterms.dateAccepted2022-03-06
prism.issueIdentifier2
prism.publicationNameAstrophysical Journal
prism.volume930
pubs.funder-project-idEuropean Research Council (695671)
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/
rioxxterms.versionVoR
rioxxterms.versionofrecord10.3847/1538-4357/ac5bd5

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