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

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

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14 Citations (Scopus)


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.
Original languageEnglish
Pages (from-to)2447-2461
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Early online date21 Jan 2019
Publication statusPublished - 1 Apr 2019


  • Galaxies: evolution
  • Galaxies: interactions
  • Galaxies: ISM
  • Galaxies: kinematics and dynamics
  • Galaxies: starburst
  • Galaxies: star formation


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