The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates
Stars form in cold molecular clouds. However, molecular gas is difficult to observe because the most abundant molecule (H2) lacks a permanent dipole moment. Rotational transitions of CO are often used as a tracer of H2, but CO is much less abundant and the conversion from CO intensity to H2 mass is...
Main Authors: | , , , , , , , , , , , , , , , , , , |
---|---|
Format: | Text |
Language: | unknown |
Published: |
arXiv
2017
|
Subjects: | |
Online Access: | https://dx.doi.org/10.48550/arxiv.1703.09224 https://arxiv.org/abs/1703.09224 |
id |
ftdatacite:10.48550/arxiv.1703.09224 |
---|---|
record_format |
openpolar |
spelling |
ftdatacite:10.48550/arxiv.1703.09224 2023-05-15T18:11:30+02:00 The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates Federrath, Christoph Salim, Diane M. Medling, Anne M. Davies, Rebecca L. Yuan, Tiantian Bian, Fuyan Groves, Brent A. Ho, I-Ting Sharp, Robert Kewley, Lisa J. Sweet, Sarah M. Richards, Samuel N. Bryant, Julia J. Brough, Sarah Croom, Scott Scott, Nicholas Lawrence, Jon Konstantopoulos, Iraklis Goodwin, Michael 2017 https://dx.doi.org/10.48550/arxiv.1703.09224 https://arxiv.org/abs/1703.09224 unknown arXiv https://dx.doi.org/10.1093/mnras/stx727 arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Astrophysics of Galaxies astro-ph.GA Cosmology and Nongalactic Astrophysics astro-ph.CO Instrumentation and Methods for Astrophysics astro-ph.IM Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences article-journal Article ScholarlyArticle Text 2017 ftdatacite https://doi.org/10.48550/arxiv.1703.09224 https://doi.org/10.1093/mnras/stx727 2022-04-01T10:48:08Z Stars form in cold molecular clouds. However, molecular gas is difficult to observe because the most abundant molecule (H2) lacks a permanent dipole moment. Rotational transitions of CO are often used as a tracer of H2, but CO is much less abundant and the conversion from CO intensity to H2 mass is often highly uncertain. Here we present a new method for estimating the column density of cold molecular gas (Sigma_gas) using optical spectroscopy. We utilise the spatially resolved H-alpha maps of flux and velocity dispersion from the Sydney-AAO Multi-object Integral-field spectrograph (SAMI) Galaxy Survey. We derive maps of Sigma_gas by inverting the multi-freefall star formation relation, which connects the star formation rate surface density (Sigma_SFR) with Sigma_gas and the turbulent Mach number (Mach). Based on the measured range of Sigma_SFR = 0.005-1.5 M_sol/yr/kpc^2 and Mach = 18-130, we predict Sigma_gas = 7-200 M_sol/pc^2 in the star-forming regions of our sample of 260 SAMI galaxies. These values are close to previously measured Sigma_gas obtained directly with unresolved CO observations of similar galaxies at low redshift. We classify each galaxy in our sample as 'Star-forming' (219) or 'Composite/AGN/Shock' (41), and find that in Composite/AGN/Shock galaxies the average Sigma_SFR, Mach, and Sigma_gas are enhanced by factors of 2.0, 1.6, and 1.3, respectively, compared to Star-forming galaxies. We compare our predictions of Sigma_gas with those obtained by inverting the Kennicutt-Schmidt relation and find that our new method is a factor of two more accurate in predicting Sigma_gas, with an average deviation of 32% from the actual Sigma_gas. : 15 pages, 8 figures, 2 tables (online material), accepted for publication in MNRAS, more info: https://www.mso.anu.edu.au/~chfeder/pubs/sami_gas/sami_gas.html 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 Cosmology and Nongalactic Astrophysics astro-ph.CO Instrumentation and Methods for Astrophysics astro-ph.IM Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences |
spellingShingle |
Astrophysics of Galaxies astro-ph.GA Cosmology and Nongalactic Astrophysics astro-ph.CO Instrumentation and Methods for Astrophysics astro-ph.IM Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences Federrath, Christoph Salim, Diane M. Medling, Anne M. Davies, Rebecca L. Yuan, Tiantian Bian, Fuyan Groves, Brent A. Ho, I-Ting Sharp, Robert Kewley, Lisa J. Sweet, Sarah M. Richards, Samuel N. Bryant, Julia J. Brough, Sarah Croom, Scott Scott, Nicholas Lawrence, Jon Konstantopoulos, Iraklis Goodwin, Michael The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates |
topic_facet |
Astrophysics of Galaxies astro-ph.GA Cosmology and Nongalactic Astrophysics astro-ph.CO Instrumentation and Methods for Astrophysics astro-ph.IM Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences |
description |
Stars form in cold molecular clouds. However, molecular gas is difficult to observe because the most abundant molecule (H2) lacks a permanent dipole moment. Rotational transitions of CO are often used as a tracer of H2, but CO is much less abundant and the conversion from CO intensity to H2 mass is often highly uncertain. Here we present a new method for estimating the column density of cold molecular gas (Sigma_gas) using optical spectroscopy. We utilise the spatially resolved H-alpha maps of flux and velocity dispersion from the Sydney-AAO Multi-object Integral-field spectrograph (SAMI) Galaxy Survey. We derive maps of Sigma_gas by inverting the multi-freefall star formation relation, which connects the star formation rate surface density (Sigma_SFR) with Sigma_gas and the turbulent Mach number (Mach). Based on the measured range of Sigma_SFR = 0.005-1.5 M_sol/yr/kpc^2 and Mach = 18-130, we predict Sigma_gas = 7-200 M_sol/pc^2 in the star-forming regions of our sample of 260 SAMI galaxies. These values are close to previously measured Sigma_gas obtained directly with unresolved CO observations of similar galaxies at low redshift. We classify each galaxy in our sample as 'Star-forming' (219) or 'Composite/AGN/Shock' (41), and find that in Composite/AGN/Shock galaxies the average Sigma_SFR, Mach, and Sigma_gas are enhanced by factors of 2.0, 1.6, and 1.3, respectively, compared to Star-forming galaxies. We compare our predictions of Sigma_gas with those obtained by inverting the Kennicutt-Schmidt relation and find that our new method is a factor of two more accurate in predicting Sigma_gas, with an average deviation of 32% from the actual Sigma_gas. : 15 pages, 8 figures, 2 tables (online material), accepted for publication in MNRAS, more info: https://www.mso.anu.edu.au/~chfeder/pubs/sami_gas/sami_gas.html |
format |
Text |
author |
Federrath, Christoph Salim, Diane M. Medling, Anne M. Davies, Rebecca L. Yuan, Tiantian Bian, Fuyan Groves, Brent A. Ho, I-Ting Sharp, Robert Kewley, Lisa J. Sweet, Sarah M. Richards, Samuel N. Bryant, Julia J. Brough, Sarah Croom, Scott Scott, Nicholas Lawrence, Jon Konstantopoulos, Iraklis Goodwin, Michael |
author_facet |
Federrath, Christoph Salim, Diane M. Medling, Anne M. Davies, Rebecca L. Yuan, Tiantian Bian, Fuyan Groves, Brent A. Ho, I-Ting Sharp, Robert Kewley, Lisa J. Sweet, Sarah M. Richards, Samuel N. Bryant, Julia J. Brough, Sarah Croom, Scott Scott, Nicholas Lawrence, Jon Konstantopoulos, Iraklis Goodwin, Michael |
author_sort |
Federrath, Christoph |
title |
The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates |
title_short |
The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates |
title_full |
The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates |
title_fullStr |
The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates |
title_full_unstemmed |
The SAMI Galaxy Survey: a new method to estimate molecular gas surface densities from star formation rates |
title_sort |
sami galaxy survey: a new method to estimate molecular gas surface densities from star formation rates |
publisher |
arXiv |
publishDate |
2017 |
url |
https://dx.doi.org/10.48550/arxiv.1703.09224 https://arxiv.org/abs/1703.09224 |
genre |
sami |
genre_facet |
sami |
op_relation |
https://dx.doi.org/10.1093/mnras/stx727 |
op_rights |
arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
op_doi |
https://doi.org/10.48550/arxiv.1703.09224 https://doi.org/10.1093/mnras/stx727 |
_version_ |
1766184151328751616 |