MOSEL and IllustrisTNG: Massive Extended Galaxies at z = 2 Quench Later Than Normal-size Galaxies
Abstract
Using the TNG100 (100 Mpc)3 simulation of the IllustrisTNG project, we demonstrate a strong connection between the onset of star formation quenching and the stellar size of galaxies. We do so by tracking the evolutionary history of extended and normal-size galaxies selected at z = 2 with $\mathrm{log}({M}_{* }/{\text{}}{M}_{\odot })$ $=\,10.2\mbox{--}11$ and stellar-half-mass-radii above and within 1σ of the stellar size-stellar mass relation, respectively. We match the stellar mass and star formation rate distributions of the two populations. By z = 1, only 36% of the extended massive galaxies have quenched, in contrast to a quenched fraction of 69% for the normal-size massive galaxies. We find that normal-size massive galaxies build up their central stellar mass without a significant increase in their stellar size between $z=2\mbox{--}4$ , whereas the stellar size of the extended massive galaxies almost doubles in the same time. In IllustrisTNG, lower black hole masses and weaker kinetic-mode feedback appears to be responsible for the delayed quenching of star formation in the extended massive galaxies. We show that relatively gas-poor mergers may be responsible for the lower central stellar density and weaker supermassive black hole feedback in the extended massive galaxies.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2021
- DOI:
- 10.3847/1538-4357/abca98
- arXiv:
- arXiv:2011.08198
- Bibcode:
- 2021ApJ...907...95G
- Keywords:
-
- Galaxies;
- Galaxy evolution;
- Hydrodynamical simulations;
- Galaxy formation;
- 573;
- 594;
- 767;
- 595;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 15 pages, 9 figures, Accepted for publication in the Astrophysical Journal