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

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Hogarth, L. M., Saintonge, A., Cortese, L., Davis, T. A., Croom, S. M., Bland-Hawthorn, J., Brough, S., Bryant, J. J., Catinella, B., Fletcher, T. J., Groves, B., Lawrence, J. S., López-Sánchez, Á. R., Owers, M. S., Richards, S. N., Roberts-Borsani, G. W., Taylor, E. N., van de Sande, J., Scott, N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: galaxies: kinematics and dynamics; galaxies: star formation; submillimetre: galaxies; galaxies: starburst; galaxies: ISM; galaxies: evolution; sami
• Online Access: https://researchers.mq.edu.au/en/publications/9a08a5c6-711a-43f5-a4ed-488dc77f62d7; https://doi.org/10.1093/mnras/staa3512; https://research-management.mq.edu.au/ws/files/139446932/138873392.pdf; http://www.scopus.com/inward/record.url?scp=85098563515&partnerID=8YFLogxK

We perform a joint analysis of high spatial resolution molecular gas and star-formation rate (SFR) maps in main-sequence starforming galaxies experiencing galactic-scale outflows of ionized 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-arcsec resolution with ALMA in 16 edge-on galaxies, which also have 2-arcsec 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 ionized gas ('outflow types') and the rest serve as control galaxies. The data set 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 are largely confined within their inner effective radius (r eff ), whereas in the control sample, the distribution is more diffuse, extending far beyond 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.