Extremely massive disc galaxies in the nearby Universe form through gas-rich minor mergers
Abstract
In our hierarchical structure-formation paradigm, the observed morphological evolution of massive galaxies – from rotationally supported discs to dispersion-dominated spheroids – is largely explained via galaxy merging. However, since mergers are likely to destroy discs, and the most massive galaxies have the richest merger histories, it is surprising that any discs exist at all at the highest stellar masses. Recent theoretical work by our group has used a cosmological, hydrodynamical simulation to suggest that extremely massive (M* > 1011.4 M⊙) discs form primarily via minor mergers between spheroids and gas-rich satellites, which create new rotational stellar components and leave discs as remnants. Here, we use UV-optical and H i data of massive galaxies, from the Sloan Digital Sky Survey, Galaxy Evolution Explorer, Dark Energy Camera Legacy Survey (DECaLS), and Arecibo Legacy Fast ALFA surveys, to test these theoretical predictions. Observed massive discs account for ∼13 per cent of massive galaxies, in good agreement with theory (∼11 per cent). ∼64 per cent of the observed massive discs exhibit tidal features, which are likely to indicate recent minor mergers, in the deep DECaLS images (compared to ∼60 per cent in their simulated counterparts). The incidence of these features is at least four times higher than in low-mass discs, suggesting that, as predicted, minor mergers play a significant (and outsized) role in the formation of these systems. The empirical star formation rates agree well with theoretical predictions and, for a small galaxy sample with H i detections, the H i masses and fractions are consistent with the range predicted by the simulation. The good agreement between theory and observations indicates that extremely massive discs are indeed remnants of recent minor mergers between spheroids and gas-rich satellites.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 14, 2022
- Source ID
- 10.1093/mnras/stac058
Entities
People
- E A Noakes-kettel
- Garreth Martin
- J E G Devriendt
- J. Silk
- P Ogle
- R. A. JACKSON
- Sugata Kaviraj
- Y Dubois
Organizations
- American Museum of Natural History
- Argonne National Laboratory
- Case Western Reserve University
- Chinese Academy of Sciences
- Drexel University
- Financiadora de Estudos e Projetos
- German Research Foundation
- Higher Education Funding Council for England
- Institut d'astrophysique de Paris
- Institute for Advanced Study
- Johns Hopkins University
- Korea Astronomy and Space Science Institute
- Lawrence Berkeley National Laboratory
- Los Alamos National Laboratory
- Max Planck Society
- National Aeronautics and Space Administration
- National Science Foundation
- New Mexico State University
- Ohio State University
- Princeton University
- SLAC National Accelerator Laboratory
- Science and Technology Facilities Council
- Space Telescope Science Institute
- Stanford University
- Texas A&M University
- United States Department of Energy
- United States Naval Observatory
- University College London
- University of Arizona
- University of Basel
- University of Chicago
- University of Edinburgh
- University of Hertfordshire
- University of Illinois Urbana–Champaign
- University of Nottingham
- University of Oxford
- University of Pennsylvania
- University of Pittsburgh
- University of Portsmouth
- University of Sussex
- University of Washington
- Yonsei University