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Early- and late-stage mergers among main sequence and starburst galaxies at 0.2 = z = 2
Version 2 2023-06-12, 09:08
Version 1 2023-06-09, 18:06
journal contribution
posted on 2023-06-12, 09:08 authored by A Cibinel, E Daddi, Mark Sargent, E Le Floc’h, D Liu, F Bournaud, P A Oesh, P Amram, A Calabrò, P-A Duc M Pannella, A Puglisi, V Perret, V KokorevWe investigate the fraction of close pairs and morphologically identified mergers on and above the star-forming main sequence (MS) at 0.2 = z =2.0. The novelty of our work lies in the use of a non-parametric morphological classification performed on resolved stellar mass maps, reducing the contamination by non-interacting, high-redshift clumpy galaxies. We find that the merger fraction rapidly rises to =70 per cent above the MS, implying that - already at z ? 1 - starburst (SB) events (?MS = 0.6) are almost always associated with a major merger (1:1 to 1:6 mass ratio). The majority of interacting galaxies in the SB region are morphologically disturbed, late-stage mergers. Pair fractions show little dependence on MS offset and pairs are more prevalent than late-stage mergers only in the lower half of the MS. In our sample, major mergers on the MS occur with a roughly equal frequency of ~5-10 per cent at all masses ? 1010 M?. The MS major merger fraction roughly doubles between z = 0.2 and 2, with morphological mergers driving the overall increase at z ? 1. The differential redshift evolution of interacting pairs and morphologically classified mergers on the MS can be reconciled by evolving observability time-scales for both pairs and morphological disturbances. The observed variation of the late-stage merger fraction with ?MS follows the perturbative 2-Star Formation Mode model, where any MS galaxy can experience a continuum of different star formation rate enhancements. This points to an SB-merger connection not only for extreme events, but also more moderate bursts which merely scatter galaxies upward within the MS, rather than fully elevating them above it.
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Publication status
- Published
File Version
- Published version
Journal
Monthly Notices Of The Royal Astronomical SocietyISSN
0035-8711Publisher
Oxford University PressExternal DOI
Issue
4Volume
485Page range
5631-5651Department affiliated with
- Physics and Astronomy Publications
Research groups affiliated with
- Astronomy Centre Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2019-06-17First Open Access (FOA) Date
2019-06-17First Compliant Deposit (FCD) Date
2019-06-17Usage metrics
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