The evolution of post-starburst galaxies from z=2 to 0.5

Wild, Vivienne; Almaini, Omar; Dunlop, Jim; Simpson, Chris; Rowlands, Kate; Bowler, Rebecca; Maltby, David; McLure, Ross

Abstract

We present the evolution in the number density and stellar mass functions of photometrically selected post-starburst galaxies in the UKIDSSUltraDeep Survey,with redshifts of 0.5<z<2 and stellar masses log (M/M�) >10. We find that this transitionary species of galaxy is rare at all redshifts, contributing ∼5 per cent of the total population at z ∼ 2, to <1 per cent by z ∼ 0.5. By comparing the mass functions of quiescent galaxies to post-starburst galaxies at three cosmic epochs, we show that rapid quenching of star formation can account for
100 per cent of quiescent galaxy formation, if the post-starburst spectral features are visible for ∼250 Myr. The flattening of the low-mass end of the quiescent galaxy stellar mass function seen at z ∼ 1 can be entirely explained by the addition of rapidly quenched galaxies. Only
if a significant fraction of post-starburst galaxies have features that are visible for longer than 250 Myr, or they acquire new gas and return to the star-forming sequence, can there be significant growth of the red sequence from a slower quenching route. The shape of the mass function of these transitory post-starburst galaxies resembles that of quiescent galaxies at z ∼ 2, with a preferred stellar mass of log (M/M�) ∼10.6, but evolves steadily to resemble that of star-forming galaxies at z < 1. This leads us to propose a dual origin for post-starburst galaxies: (1) at z >/~ 2 they are exclusively massive galaxies that have formed the bulk of their stars during a rapid assembly period, followed by complete quenching of further star formation; (2) at z </~1 they are caused by the rapid quenching of gas-rich star-forming galaxies, independent of stellar mass, possibly due to environment and/or gas-rich major mergers.

Citation

Wild, V., Almaini, O., Dunlop, J., Simpson, C., Rowlands, K., Bowler, R., Maltby, D., & McLure, R. (2016). The evolution of post-starburst galaxies from z=2 to 0.5. Monthly Notices of the Royal Astronomical Society, 463(1), 832-844. https://doi.org/10.1093/mnras/stw1996

• Journal Article Type: Article
• Acceptance Date: Aug 8, 2016
• Online Publication Date: Aug 11, 2016
• Publication Date: Nov 21, 2016
• Deposit Date: Jan 12, 2017
• Publicly Available Date: Jan 12, 2017
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 463
• Issue: 1
• Pages: 832-844
• DOI: https://doi.org/10.1093/mnras/stw1996
• Keywords: galaxies: evolution ; galaxies: formation ; galaxies: high-redshift ; galaxies: luminosity function, mass function ; galaxies: stellar content
• Public URL: https://nottingham-repository.worktribe.com/output/827738
• Publisher URL: http://mnras.oxfordjournals.org/content/463/1/832
• Contract Date: Jan 12, 2017