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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
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2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2409.06572 |
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| _version_ | 1866908294858145792 |
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| author | Sargent, Mark T. Ellison, S. L. Mendel, J. T. Saintonge, A. Molnár, D. Cs. Schwandt, T. Scudder, J. M. Violino, G. |
| author_facet | Sargent, Mark T. Ellison, S. L. Mendel, J. T. Saintonge, A. Molnár, D. Cs. Schwandt, T. Scudder, J. M. Violino, G. |
| contents | Exploiting IRAM 30m CO spectroscopy, we find that SDSS post-merger galaxies display gas fractions and depletion times enhanced by 25-50%, a mildly higher CO excitation, and standard molecular-to-atomic gas ratios, compared to non-interacting galaxies with similar redshift, stellar mass ($M_{\star}$) and star-formation rate (SFR). To place these results in context, we compile further samples of interacting or starbursting galaxies, from pre-coalescence kinematic pairs to post-starbursts, carefully homogenising gas mass, $M_{\star}$ and SFR measurements in the process. We explore systematics by duplicating our analysis for different SFR and $M_{\star}$ estimators, finding good qualitative agreement in general. Gas fractions and depletion times are enhanced in interacting pairs, albeit by less than for post-mergers. Among all samples studied, gas fraction and depletion time enhancements appear largest in young (a few 100 Myr) post-starbursts. While there is only partial overlap between post-mergers and post-starbursts, this suggests that molecular gas reservoirs are boosted throughout most stages of galaxy interactions, plausibly due to torque-driven inflows of halo gas and gas compression. The gas fraction and depletion time offsets of mergers and post-starbursts anti-correlate with distance from the galaxy main sequence $Δ({\rm MS})$, evidencing the role of SFE in driving the high SFRs of the strongest starbursts. Post-starbursts display the steepest dependency of gas fraction and SFE-offsets on $Δ({\rm MS})$, with an evolving normalisation that reflects gas reservoir depletion over time. Our multi-sample analysis paints a coherent picture of the starburst-merger connection throughout the low-z merger sequence. It reconciles contradictory literature findings by highlighting that gas fraction enhancements and SFE variations both play their part in merger-driven star formation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2409_06572 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The molecular gas content throughout the low-z merger sequence Sargent, Mark T. Ellison, S. L. Mendel, J. T. Saintonge, A. Molnár, D. Cs. Schwandt, T. Scudder, J. M. Violino, G. Astrophysics of Galaxies Exploiting IRAM 30m CO spectroscopy, we find that SDSS post-merger galaxies display gas fractions and depletion times enhanced by 25-50%, a mildly higher CO excitation, and standard molecular-to-atomic gas ratios, compared to non-interacting galaxies with similar redshift, stellar mass ($M_{\star}$) and star-formation rate (SFR). To place these results in context, we compile further samples of interacting or starbursting galaxies, from pre-coalescence kinematic pairs to post-starbursts, carefully homogenising gas mass, $M_{\star}$ and SFR measurements in the process. We explore systematics by duplicating our analysis for different SFR and $M_{\star}$ estimators, finding good qualitative agreement in general. Gas fractions and depletion times are enhanced in interacting pairs, albeit by less than for post-mergers. Among all samples studied, gas fraction and depletion time enhancements appear largest in young (a few 100 Myr) post-starbursts. While there is only partial overlap between post-mergers and post-starbursts, this suggests that molecular gas reservoirs are boosted throughout most stages of galaxy interactions, plausibly due to torque-driven inflows of halo gas and gas compression. The gas fraction and depletion time offsets of mergers and post-starbursts anti-correlate with distance from the galaxy main sequence $Δ({\rm MS})$, evidencing the role of SFE in driving the high SFRs of the strongest starbursts. Post-starbursts display the steepest dependency of gas fraction and SFE-offsets on $Δ({\rm MS})$, with an evolving normalisation that reflects gas reservoir depletion over time. Our multi-sample analysis paints a coherent picture of the starburst-merger connection throughout the low-z merger sequence. It reconciles contradictory literature findings by highlighting that gas fraction enhancements and SFE variations both play their part in merger-driven star formation. |
| title | The molecular gas content throughout the low-z merger sequence |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2409.06572 |