The structure of post-starburst galaxies at 0.5 < z < 2: evidence for two distinct quenching routes at different epochs

Maltby, David T.; Almaini, Omar; Wild, Vivienne; Hatch, Nina A.; Hartley, William G.; Simpson, Chris; Rowlands, Kate; Socolovsky, Miguel

Abstract

We present an analysis of the structure of post-starburst (PSB) galaxies in the redshift range 0.5 less than z less than 2, using a photometrically selected sample identified in the Ultra Deep Survey field. We examine the structure of ∼80 of these transient galaxies using radial light μ(r) profiles obtained from CANDELS Hubble Space Telescope near-infrared/optical imaging, and compare to a large sample of ∼2000 passive and star-forming galaxies. For each population, we determine their typical structural properties (effective radius re, Sersic index n) and find significant differences in PSB structure at different epochs. At high redshift (z>1), PSBs are typically massive (M∗>1010M), very compact and exhibit high Sersic indices, with structures that differ significantly from their star-forming progenitors but are similar to massivepassive galaxies. In contrast, at lower redshift (0.5 less than z less than 1), PSBs are generally of low mass(M∗ less than 1010M) and exhibit compact but less concentrated profiles (i.e. lower Sersic indices), with structures similar to low-mass passive discs. Furthermore, for both epochs, we find remarkably consistent PSB structure across the optical/near-infrared wavebands (which largely trace different stellar populations), suggesting that any preceding starburst and/or quenchingin PSBs was not strongly centralized. Taken together, these results imply that PSBs at z>1 have been recently quenched during a major disruptive event (e.g. merger or protogalactic collapse) that formed a compact remnant, while at z less than 1 an alternative less disruptive process is primarily responsible. Our results suggest that high-z PSBs are an intrinsically different population to those at lower redshifts, and indicate different quenching routes are active at different epochs.

Citation

Maltby, D. T., Almaini, O., Wild, V., Hatch, N. A., Hartley, W. G., Simpson, C., …Socolovsky, M. (2018). The structure of post-starburst galaxies at 0.5 < z < 2: evidence for two distinct quenching routes at different epochs. Monthly Notices of the Royal Astronomical Society, 480(1), 381-401. https://doi.org/10.1093/mnras/sty1794

• Journal Article Type: Article
• Acceptance Date: Jul 5, 2018
• Online Publication Date: Jul 5, 2018
• Publication Date: Oct 11, 2018
• Deposit Date: Nov 22, 2018
• Publicly Available Date: Nov 22, 2018
• 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: 480
• Issue: 1
• Pages: 381-401
• DOI: https://doi.org/10.1093/mnras/sty1794
• Keywords: galaxies: evolution, galaxies: fundamental parameters, galaxies: high-redshift, galaxies: structure
• Public URL: https://nottingham-repository.worktribe.com/output/1300452
• Publisher URL: https://academic.oup.com/mnras/article/480/1/381/5049326
• Related Public URLs: http://eprints.nottingham.ac.uk/53273/
• Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomial Society ©: 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.