The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions
We investigate the mean locally-measured velocity dispersions of ionised gas ($σ_{\rm gas}$) and stars ($σ_*$) for 1090 galaxies with stellar masses $\log\,(M_*/M_{\odot}) \geq 9.5$ from the SAMI Galaxy Survey. For star-forming galaxies, $σ_*$ tends to be larger than $σ_{\rm gas}$, suggesting that s...
Main Authors: | , , , , , , , , , , , , , , , , , , |
---|---|
Format: | Text |
Language: | unknown |
Published: |
arXiv
2022
|
Subjects: | |
Online Access: | https://dx.doi.org/10.48550/arxiv.2202.10469 https://arxiv.org/abs/2202.10469 |
id |
ftdatacite:10.48550/arxiv.2202.10469 |
---|---|
record_format |
openpolar |
spelling |
ftdatacite:10.48550/arxiv.2202.10469 2023-05-15T18:11:48+02:00 The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions Oh, Sree Colless, Matthew D'Eugenio, Francesco Croom, Scott M. Cortese, Luca Groves, Brent Kewley, Lisa J. van de Sande, Jesse Zovaro, Henry Varidel, Mathew R. Barsanti, Stefania Brough, Sarah Bryant, Julia J. Casura, Sarah Lawrence, Jon S. Lorente, Nuria P. F. Medling, Anne M. Owers, Matt S. Yi, Sukyoung K. 2022 https://dx.doi.org/10.48550/arxiv.2202.10469 https://arxiv.org/abs/2202.10469 unknown arXiv https://dx.doi.org/10.1093/mnras/stac509 arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Astrophysics of Galaxies astro-ph.GA FOS Physical sciences article-journal Article ScholarlyArticle Text 2022 ftdatacite https://doi.org/10.48550/arxiv.2202.10469 https://doi.org/10.1093/mnras/stac509 2022-04-01T12:55:33Z We investigate the mean locally-measured velocity dispersions of ionised gas ($σ_{\rm gas}$) and stars ($σ_*$) for 1090 galaxies with stellar masses $\log\,(M_*/M_{\odot}) \geq 9.5$ from the SAMI Galaxy Survey. For star-forming galaxies, $σ_*$ tends to be larger than $σ_{\rm gas}$, suggesting that stars are in general dynamically hotter than the ionised gas (asymmetric drift). The difference between $σ_{\rm gas}$ and $σ_*$ ($Δσ$) correlates with various galaxy properties. We establish that the strongest correlation of $Δσ$ is with beam smearing, which inflates $σ_{\rm gas}$ more than $σ_*$, introducing a dependence of $Δσ$ on both the effective radius relative to the point spread function and velocity gradients. The second-strongest correlation is with the contribution of active galactic nuclei (AGN) (or evolved stars) to the ionised gas emission, implying the gas velocity dispersion is strongly affected by the power source. In contrast, using the velocity dispersion measured from integrated spectra ($σ_{\rm aper}$) results in less correlation between the aperture-based $Δσ$ ($Δσ_{\rm aper}$) and the power source. This suggests that the AGN (or old stars) dynamically heat the gas without causing significant deviations from dynamical equilibrium. Although the variation of $Δσ_{\rm aper}$ is much smaller than that of $Δσ$, a correlation between $Δσ_{\rm aper}$ and gas velocity gradient is still detected, implying there is a small bias in dynamical masses derived from stellar and ionised gas velocity dispersions. : 18 pages, 13 figures Text sami DataCite Metadata Store (German National Library of Science and Technology) |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
unknown |
topic |
Astrophysics of Galaxies astro-ph.GA FOS Physical sciences |
spellingShingle |
Astrophysics of Galaxies astro-ph.GA FOS Physical sciences Oh, Sree Colless, Matthew D'Eugenio, Francesco Croom, Scott M. Cortese, Luca Groves, Brent Kewley, Lisa J. van de Sande, Jesse Zovaro, Henry Varidel, Mathew R. Barsanti, Stefania Brough, Sarah Bryant, Julia J. Casura, Sarah Lawrence, Jon S. Lorente, Nuria P. F. Medling, Anne M. Owers, Matt S. Yi, Sukyoung K. The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions |
topic_facet |
Astrophysics of Galaxies astro-ph.GA FOS Physical sciences |
description |
We investigate the mean locally-measured velocity dispersions of ionised gas ($σ_{\rm gas}$) and stars ($σ_*$) for 1090 galaxies with stellar masses $\log\,(M_*/M_{\odot}) \geq 9.5$ from the SAMI Galaxy Survey. For star-forming galaxies, $σ_*$ tends to be larger than $σ_{\rm gas}$, suggesting that stars are in general dynamically hotter than the ionised gas (asymmetric drift). The difference between $σ_{\rm gas}$ and $σ_*$ ($Δσ$) correlates with various galaxy properties. We establish that the strongest correlation of $Δσ$ is with beam smearing, which inflates $σ_{\rm gas}$ more than $σ_*$, introducing a dependence of $Δσ$ on both the effective radius relative to the point spread function and velocity gradients. The second-strongest correlation is with the contribution of active galactic nuclei (AGN) (or evolved stars) to the ionised gas emission, implying the gas velocity dispersion is strongly affected by the power source. In contrast, using the velocity dispersion measured from integrated spectra ($σ_{\rm aper}$) results in less correlation between the aperture-based $Δσ$ ($Δσ_{\rm aper}$) and the power source. This suggests that the AGN (or old stars) dynamically heat the gas without causing significant deviations from dynamical equilibrium. Although the variation of $Δσ_{\rm aper}$ is much smaller than that of $Δσ$, a correlation between $Δσ_{\rm aper}$ and gas velocity gradient is still detected, implying there is a small bias in dynamical masses derived from stellar and ionised gas velocity dispersions. : 18 pages, 13 figures |
format |
Text |
author |
Oh, Sree Colless, Matthew D'Eugenio, Francesco Croom, Scott M. Cortese, Luca Groves, Brent Kewley, Lisa J. van de Sande, Jesse Zovaro, Henry Varidel, Mathew R. Barsanti, Stefania Brough, Sarah Bryant, Julia J. Casura, Sarah Lawrence, Jon S. Lorente, Nuria P. F. Medling, Anne M. Owers, Matt S. Yi, Sukyoung K. |
author_facet |
Oh, Sree Colless, Matthew D'Eugenio, Francesco Croom, Scott M. Cortese, Luca Groves, Brent Kewley, Lisa J. van de Sande, Jesse Zovaro, Henry Varidel, Mathew R. Barsanti, Stefania Brough, Sarah Bryant, Julia J. Casura, Sarah Lawrence, Jon S. Lorente, Nuria P. F. Medling, Anne M. Owers, Matt S. Yi, Sukyoung K. |
author_sort |
Oh, Sree |
title |
The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions |
title_short |
The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions |
title_full |
The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions |
title_fullStr |
The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions |
title_full_unstemmed |
The SAMI Galaxy Survey: the difference between ionised gas and stellar velocity dispersions |
title_sort |
sami galaxy survey: the difference between ionised gas and stellar velocity dispersions |
publisher |
arXiv |
publishDate |
2022 |
url |
https://dx.doi.org/10.48550/arxiv.2202.10469 https://arxiv.org/abs/2202.10469 |
genre |
sami |
genre_facet |
sami |
op_relation |
https://dx.doi.org/10.1093/mnras/stac509 |
op_rights |
arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
op_doi |
https://doi.org/10.48550/arxiv.2202.10469 https://doi.org/10.1093/mnras/stac509 |
_version_ |
1766184421405229056 |