WISDOM project -- XXIII. Star-formation efficiencies of eight early-type galaxies and bulges observed with SITELLE and ALMA
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Lu, Anan Haggard, Daryl Bureau, Martin Gensior, Jindra Robert, Carmelle Williams, Thomas G. Liang, Fu-Heng Choi, Woorak Davis, Timothy A. Ruffa, Ilaria Babic, Sara Boyce, Hope Cappellari, Michele Cheung, Benjamin Drissen, Laurent Elford, Jacob S. Martin, Thomas Rhea, Carter Rousseau-Nepton, Laurie Sarzi, Marc Zhang, Hengyue |
| author_facet | Lu, Anan Haggard, Daryl Bureau, Martin Gensior, Jindra Robert, Carmelle Williams, Thomas G. Liang, Fu-Heng Choi, Woorak Davis, Timothy A. Ruffa, Ilaria Babic, Sara Boyce, Hope Cappellari, Michele Cheung, Benjamin Drissen, Laurent Elford, Jacob S. Martin, Thomas Rhea, Carter Rousseau-Nepton, Laurie Sarzi, Marc Zhang, Hengyue |
| contents | Early-type galaxies (ETGs) are known to harbour dense spheroids of stars with scarce star formation (SF). Approximately a quarter of these galaxies have rich molecular gas reservoirs yet do not form stars efficiently. These gas-rich ETGs have properties similar to those of bulges at the centres of spiral galaxies. We use spatially-resolved observations (~ 100 pc resolution) of warm ionised-gas emission lines (Hbeta, [O III], [N II], Halpha and [S II]) from the imaging Fourier transform spectrograph SITELLE at the Canada-France-Hawaii Telescope and cold molecular gas (12CO(2-1) or 12CO(3-2)) from the Atacama Large Millimeter/submillimeter Array (ALMA) to study the SF properties of 8 ETGs and bulges. We use the ionised-gas emission lines to classify the ionisation mechanisms and demonstrate a complete absence of regions dominated by SF ionisation in these ETGs and bulges, despite abundant cold molecular gas. The ionisation classifications also show that our ETGs and bulges are dominated by old stellar populations. We use the molecular gas surface densities and Halpha-derived SF rates (in spiral galaxies outside of the bulges) or upper limits (in ETGs and bulges) to constrain the depletion times (inverse of the SF efficiencies), suggesting again suppressed SF in our ETGs and bulges. Finally, we use the molecular gas velocity fields to measure the gas kinematics, and show that bulge dynamics, particularly the strong shear due to the deep and steep gravitational potential wells, is an important SF-regulation mechanism for at least half of our sample galaxies. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_17961 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | WISDOM project -- XXIII. Star-formation efficiencies of eight early-type galaxies and bulges observed with SITELLE and ALMA Lu, Anan Haggard, Daryl Bureau, Martin Gensior, Jindra Robert, Carmelle Williams, Thomas G. Liang, Fu-Heng Choi, Woorak Davis, Timothy A. Ruffa, Ilaria Babic, Sara Boyce, Hope Cappellari, Michele Cheung, Benjamin Drissen, Laurent Elford, Jacob S. Martin, Thomas Rhea, Carter Rousseau-Nepton, Laurie Sarzi, Marc Zhang, Hengyue Astrophysics of Galaxies Early-type galaxies (ETGs) are known to harbour dense spheroids of stars with scarce star formation (SF). Approximately a quarter of these galaxies have rich molecular gas reservoirs yet do not form stars efficiently. These gas-rich ETGs have properties similar to those of bulges at the centres of spiral galaxies. We use spatially-resolved observations (~ 100 pc resolution) of warm ionised-gas emission lines (Hbeta, [O III], [N II], Halpha and [S II]) from the imaging Fourier transform spectrograph SITELLE at the Canada-France-Hawaii Telescope and cold molecular gas (12CO(2-1) or 12CO(3-2)) from the Atacama Large Millimeter/submillimeter Array (ALMA) to study the SF properties of 8 ETGs and bulges. We use the ionised-gas emission lines to classify the ionisation mechanisms and demonstrate a complete absence of regions dominated by SF ionisation in these ETGs and bulges, despite abundant cold molecular gas. The ionisation classifications also show that our ETGs and bulges are dominated by old stellar populations. We use the molecular gas surface densities and Halpha-derived SF rates (in spiral galaxies outside of the bulges) or upper limits (in ETGs and bulges) to constrain the depletion times (inverse of the SF efficiencies), suggesting again suppressed SF in our ETGs and bulges. Finally, we use the molecular gas velocity fields to measure the gas kinematics, and show that bulge dynamics, particularly the strong shear due to the deep and steep gravitational potential wells, is an important SF-regulation mechanism for at least half of our sample galaxies. |
| title | WISDOM project -- XXIII. Star-formation efficiencies of eight early-type galaxies and bulges observed with SITELLE and ALMA |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2504.17961 |