Evolution of the cold gas properties of simulated post-starburst galaxies

Davis, Timothy A; van de Voort, Freeke; Rowlands, Kate; McAlpine, Stuart; Wild, Vivienne; Crain, Robert A

Abstract

Post-starburst galaxies are typically considered to be a transition population, en route to the red sequence after a recent quenching event. Despite this, recent observations have shown that these objects typically have large reservoirs of cold molecular gas. In this paper we study the star-forming gas properties of a large sample of post-starburst galaxies selected from the cosmological, hydrodynamical EAGLE simulations. These objects resemble observed high-mass post-starburst galaxies both spectroscopically and in terms of their space density, stellar mass distribution, and sizes. We find that the vast majority of simulated post-starburst galaxies have significant gas reservoirs, with star-forming gas masses ≈109 M⊙, in good agreement with those seen in observational samples. The simulation reproduces the observed time evolution of the gas fraction of the post-starburst galaxy population, with the average galaxy losing ≈90 per cent of its star-forming interstellar medium in only ≈600 Myr. A variety of gas consumption/loss processes are responsible for this rapid evolution, including mergers and environmental effects, while active galactic nuclei play only a secondary role. The fast evolution in the gas fraction of post-starburst galaxies is accompanied by a clear decrease in the efficiency of star formation due to a decrease in the dense gas fraction. We predict that forthcoming ALMA observations of the gas reservoirs of low-redshift post-starburst galaxies will show that the molecular gas is typically compact and has disturbed kinematics, reflecting the disruptive nature of many of the evolutionary pathways that build up the post-starburst galaxy population.

Citation

Davis, T. A., van de Voort, F., Rowlands, K., McAlpine, S., Wild, V., & Crain, R. A. (2019). Evolution of the cold gas properties of simulated post-starburst galaxies. Monthly Notices of the Royal Astronomical Society, 484(2), 2447-2461. https://doi.org/10.1093/mnras/stz180

• Journal Article Type: Article
• Acceptance Date: Jan 14, 2019
• Online Publication Date: Jan 21, 2019
• Publication Date: May 1, 2019
• Deposit Date: Apr 2, 2019
• Publicly Available Date: Apr 2, 2019
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 484
• Issue: 2
• Pages: 2447-2461
• DOI: https://doi.org/10.1093/mnras/stz180
• Public URL: https://durham-repository.worktribe.com/output/1304873