Evolution of the cold gas properties of simulated post-starburst galaxies. Issue 2 (21st January 2019)

• Record Type: Journal Article
• Authors: Davis, Timothy A; van de Voort, Freeke; Rowlands, Kate; McAlpine, Stuart; Wild, Vivienne; Crain, Robert A
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 484:Issue 2(2019)
• Page Start: 2447
• Page End: 2461
• Publication Date: 2019-01-21
• Subjects: galaxies: evolution -- galaxies: interactions -- galaxies: ISM -- galaxies: kinematics and dynamics -- galaxies: starburst -- galaxies: star formation; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz180
• Languages: English
• ISSNs: 0035-8711

Abstract

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 ≈10 9 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.