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Spheroidal post-mergers in the local Universe
journal contribution
posted on 2023-05-17, 11:24 authored by Carpineti, A, Kaviraj, S, Darg, D, Lintott, C, Schawinski, K, Stanislav ShabalaStanislav ShabalaGalaxy merging is a fundamental aspect of the standard hierarchical galaxy formation paradigm. Recently, the Galaxy Zoo project has compiled a large, homogeneous catalogue of 3373 mergers, through direct visual inspection of the entire Sloan Digital Sky Survey spectroscopic sample. We explore a subset of galaxies from this catalogue that are spheroidal ‘post-mergers’ (SPMs) – where a single remnant is in the final stages of relaxation after the merger and shows evidence for a dominant bulge, making them plausible progenitors of early-type galaxies. Our results indicate that the SPMs have bluer colours than the general early-type galaxy population possibly due to merger-induced star formation. An analysis using optical emission-line ratios indicates that 20 of our SPMs exhibit LINER or Seyfert-like activity (68 per cent), while the remaining 10 galaxies are classified as either star forming (16 per cent) or quiescent (16 per cent). A comparison to the emission-line activity in the ongoing mergers from Darg et al. indicates that the active galactic nuclei (AGN) fraction rises in the post-mergers, suggesting that the AGN phase probably becomes dominant only in the very final stages of the merger process. The optical colours of the SPMs and the plausible mass ratios for their progenitors indicate that, while a minority are consistent with major mergers between two early-type galaxies, the vast majority are remnants of major mergers where at least one progenitor is a late-type galaxy.
Funding
Australian Research Council
History
Publication title
Monthly Notices of the Royal Astronomical SocietyVolume
420Pagination
2139-2146ISSN
1365-2966Department/School
School of Natural SciencesPublisher
Wiley-Blackwell Publishing Ltd.Place of publication
United KingdomRights statement
The definitive published version is available online at: http://www3.interscience.wiley.com/Repository Status
- Restricted