The merger fraction of post-starburst galaxies in UNIONS
Abstract
Post-starburst galaxies (PSBs) are defined as having experienced a recent burst of star formation, followed by a prompt truncation in further activity. Identifying the mechanism(s) causing a galaxy to experience a post-starburst phase therefore provides integral insight into the causes of rapid quenching. Galaxy mergers have long been proposed as a possible post-starburst trigger. Effectively testing this hypothesis requires a large spectroscopic galaxy survey to identify the rare PSBs as well as high-quality imaging and robust morphology metrics to identify mergers. We bring together these critical elements by selecting PSBs from the overlap of the Sloan Digital Sky Survey and the Canada–France Imaging Survey and applying a suite of classification methods: non-parametric morphology metrics such as asymmetry and Gini-M20, a convolutional neural network trained to identify post-merger galaxies, and visual classification. This work is therefore the largest and most comprehensive assessment of the merger fraction of PSBs to date. We find that the merger fraction of PSBs ranges from 19 per cent to 42 per cent depending on the merger identification method and details of the PSB sample selection. These merger fractions represent an excess of 3–46× relative to non-PSB control samples. Our results demonstrate that mergers play a significant role in generating PSBs, but that other mechanisms are also required. However, applying our merger identification metrics to known post-mergers in the IllustrisTNG simulation shows that 70 per cent of recent post-mergers (≲200 Myr) would not be detected. Thus, we cannot exclude the possibility that nearly all PSBs have undergone a merger in their recent past.
Citation
Wilkinson , S , Ellison , S L , Bottrell , C , Bickley , R W , Gwyn , S , Cuillandre , J-C & Wild , V 2022 , ' The merger fraction of post-starburst galaxies in UNIONS ' , Monthly Notices of the Royal Astronomical Society , vol. 516 , no. 3 , pp. 4354-4372 . https://doi.org/10.1093/mnras/stac1962
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Rights
Copyright © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at https://doi.org/10.1093/mnras/stac1962.
Description
Funding information: CB gratefully acknowledges support from the Natural Sciences and Engineering Council of Canada (NSERC) as part of their post-doctoral fellowship program (PDF-546234-2020) and VW acknowledges STFC grant ST/V000861/1.Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.
Related items
Showing items related by title, author, creator and subject.
-
SDSS-IV MaNGA: How the stellar populations of passive central galaxies depend on stellar and halo mass
Oyarzún, Grecco A.; Bundy, Kevin; Westfall, Kyle B.; Tinker, Jeremy L.; Belfiore, Francesco; Argudo-Fernández, Maria; Zheng, Zheng; Conroy, Charlie; Masters, Karen L.; Wake, David; Law, David R.; McDermid, Richard M.; Aragón-Salamanca, Alfonso; Parikh, Taniya; Yan, Renbin; Bershady, Matthew; Sánchez, Sebastián F.; Andrews, Brett H.; Fernández-Trincado, José G.; Lane, Richard R.; Bizyaev, D.; Boardman, Nicholas Fraser; Lacerna, Ivan; Brownstein, J. R.; Drory, Niv; Zhang, Kai (2022-07-06) - Journal articleWe analyze spatially resolved and co-added SDSS-IV MaNGA spectra with signal-to-noise ratio ∼100 from 2200 passive central galaxies (z ∼ 0.05) to understand how central galaxy assembly depends on stellar mass (M*) and halo ... -
Secular-and merger-built bulges in barred galaxies
Mendez Abreu, Jairo; Debattista, V. P.; Corsini, E. M.; Aguerri, J. A. L. (2014-12) - Journal articleContext. Historically, galaxy bulges were thought to be single-component objects at the center of galaxies. However, this picture is now questioned since different bulge types with different formation paths, namely classical ... -
Galaxy And Mass Assembly (GAMA) : galaxy close pairs, mergers and the future fate of stellar mass
Robotham, A. S. G.; Driver, S. P.; Davies, L. J. M.; Hopkins, A. M.; Baldry, I. K.; Agius, N. K.; Bauer, A. E.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cluver, M.; De Propris, R.; Drinkwater, M. J.; Holwerda, B. W.; Kelvin, L. S.; Lara-Lopez, M. A.; Liske, J.; Lopez-Sanchez, A. R.; Loveday, J.; Mahajan, S.; McNaught-Roberts, T.; Moffett, A.; Norberg, P.; Obreschkow, D.; Owers, M. S.; Penny, S. J.; Pimbblet, K.; Prescott, M.; Taylor, E. N.; van Kampen, E.; Wilkins, S. M. (2014-11-11) - Journal articleWe use a highly complete subset of the Galaxy And Mass Assembly II (GAMA-II) redshift sample to fully describe the stellar mass dependence of close pairs and mergers between 10(8) and 10(12)M(circle dot). Using the analytic ...