The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics

Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h_3 (~skewness) and h_4 (~kurtosis) in galaxies to their cosmological assembly history. Here, we assess these results by measuring the stellar kinematics on a...

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Published in:The Astrophysical Journal
Main Authors: van de Sande, Jesse, Medling, Anne M.
Format: Article in Journal/Newspaper
Language:English
Published: American Astronomical Society 2017
Subjects:
Online Access:https://authors.library.caltech.edu/73771/
https://authors.library.caltech.edu/73771/1/Sande_2017_ApJ_835_104.pdf
https://authors.library.caltech.edu/73771/2/1611.07039v1.pdf
https://resolver.caltech.edu/CaltechAUTHORS:20170127-091339895
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spelling ftcaltechauth:oai:authors.library.caltech.edu:73771 2023-05-15T18:11:25+02:00 The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics van de Sande, Jesse Medling, Anne M. 2017-01-20 application/pdf https://authors.library.caltech.edu/73771/ https://authors.library.caltech.edu/73771/1/Sande_2017_ApJ_835_104.pdf https://authors.library.caltech.edu/73771/2/1611.07039v1.pdf https://resolver.caltech.edu/CaltechAUTHORS:20170127-091339895 en eng American Astronomical Society https://authors.library.caltech.edu/73771/1/Sande_2017_ApJ_835_104.pdf https://authors.library.caltech.edu/73771/2/1611.07039v1.pdf van de Sande, Jesse and Medling, Anne M. (2017) The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics. Astrophysical Journal, 835 (1). Art. No. 104. ISSN 0004-637X. doi:10.3847/1538-4357/835/1/104. https://resolver.caltech.edu/CaltechAUTHORS:20170127-091339895 <https://resolver.caltech.edu/CaltechAUTHORS:20170127-091339895> other Article PeerReviewed 2017 ftcaltechauth https://doi.org/10.3847/1538-4357/835/1/104 2021-11-18T18:40:32Z Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h_3 (~skewness) and h_4 (~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 (λ_(R_e)) and ellipticity (ε_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 h_3 versus V/σ anti-correlation, whereas quasi-regular and non-regular rotators show a more vertical relation in h_3 and V/σ. Motivated by recent cosmological simulations, we develop an alternative approach to kinematically classify galaxies from their individual h_3 versus V/σ 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 λ_(R_e) - ε_e values can show distinctly different h_3 - V/σ signatures. Class 5 objects are previously unidentified fast rotators that show a weak h_3 versus V/σ 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 h_3 versus V/σ as evidence for disks in most fast rotators, suggesting a dearth of gas-poor mergers among fast rotators. Article in Journal/Newspaper sami Caltech Authors (California Institute of Technology) The Astrophysical Journal 835 1 104
institution Open Polar
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language English
description Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h_3 (~skewness) and h_4 (~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 (λ_(R_e)) and ellipticity (ε_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 h_3 versus V/σ anti-correlation, whereas quasi-regular and non-regular rotators show a more vertical relation in h_3 and V/σ. Motivated by recent cosmological simulations, we develop an alternative approach to kinematically classify galaxies from their individual h_3 versus V/σ 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 λ_(R_e) - ε_e values can show distinctly different h_3 - V/σ signatures. Class 5 objects are previously unidentified fast rotators that show a weak h_3 versus V/σ 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 h_3 versus V/σ as evidence for disks in most fast rotators, suggesting a dearth of gas-poor mergers among fast rotators.
format Article in Journal/Newspaper
author van de Sande, Jesse
Medling, Anne M.
spellingShingle van de Sande, Jesse
Medling, Anne M.
The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics
author_facet van de Sande, Jesse
Medling, Anne M.
author_sort van de Sande, Jesse
title The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics
title_short The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics
title_full The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics
title_fullStr The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics
title_full_unstemmed The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics
title_sort sami galaxy survey: revisiting galaxy classification through high-order stellar kinematics
publisher American Astronomical Society
publishDate 2017
url https://authors.library.caltech.edu/73771/
https://authors.library.caltech.edu/73771/1/Sande_2017_ApJ_835_104.pdf
https://authors.library.caltech.edu/73771/2/1611.07039v1.pdf
https://resolver.caltech.edu/CaltechAUTHORS:20170127-091339895
genre sami
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op_relation https://authors.library.caltech.edu/73771/1/Sande_2017_ApJ_835_104.pdf
https://authors.library.caltech.edu/73771/2/1611.07039v1.pdf
van de Sande, Jesse and Medling, Anne M. (2017) The SAMI Galaxy Survey: Revisiting Galaxy Classification through High-order Stellar Kinematics. Astrophysical Journal, 835 (1). Art. No. 104. ISSN 0004-637X. doi:10.3847/1538-4357/835/1/104. https://resolver.caltech.edu/CaltechAUTHORS:20170127-091339895 <https://resolver.caltech.edu/CaltechAUTHORS:20170127-091339895>
op_rights other
op_doi https://doi.org/10.3847/1538-4357/835/1/104
container_title The Astrophysical Journal
container_volume 835
container_issue 1
container_start_page 104
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