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arXiv · 2011.03566

Centrally concentrated molecular gas driving galactic-scale ionised gas outflows in star-forming galaxies

L. M. Hogarth·A. Saintonge·L. Cortese·T. A. Davis·S. M. Croom·J. Bland-Hawthorn·S. Brough·J. J. Bryant·B. Catinella·T. J. Fletcher·B. Groves·J. S. Lawrence·A. R. Lopez-Sanchez·M. S. Owers·S. N. Richards·G. W. Roberts-Borsani·E. N. Taylor·J. van de Sande·N. Scott
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Abstract

We perform a joint-analysis of high spatial resolution molecular gas and star-formation rate (SFR) maps in main-sequence star-forming galaxies experiencing galactic-scale outflows of ionised gas. Our aim is to understand the mechanism that determines which galaxies are able to launch these intense winds. We observed CO(1-0) at 1" resolution with ALMA in 16 edge-on galaxies, which also have 2" spatial resolution optical integral field observations from the SAMI Galaxy Survey. Half the galaxies in the sample were previously identified as harbouring intense and large-scale outflows of ionised gas ("outflow-types"), the rest serve as control galaxies. The dataset is complemented by integrated CO(1-0) observations from the IRAM 30-m telescope to probe the total molecular gas reservoirs. We find that the galaxies powering outflows do not possess significantly different global gas fractions or star-formation efficiencies when compared with a control sample. However, the ALMA maps reveal that the molecular gas in the outflow-type galaxies is distributed more centrally than in the control galaxies. For our outflow-type objects, molecular gas and star-formation is largely confined within their inner effective radius ($\rm r_{eff}$), whereas in the control sample the distribution is more diffuse, extending far beyond $\rm r_{eff}$. We infer that outflows in normal star-forming galaxies may be caused by dynamical mechanisms that drive molecular gas into their central regions, which can result in locally-enhanced gas surface density and star-formation.

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L. M. Hogarth, A. Saintonge, L. Cortese, T. A. Davis, S. M. Croom, J. Bland-Hawthorn, S. Brough, J. J. Bryant, B. Catinella, T. J. Fletcher, B. Groves, J. S. Lawrence, A. R. Lopez-Sanchez, M. S. Owers, S. N. Richards, G. W. Roberts-Borsani, E. N. Taylor, J. van de Sande, N. Scott. 2020-12-10. Centrally concentrated molecular gas driving galactic-scale ionised gas outflows in star-forming galaxies. https://doi.org/10.1093/mnras%2Fstaa3512

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