Modeling Evolution of Galactic Bars at Cosmic Dawn
Abstract
We study the evolution of galactic bars using a suite of very high-resolution zoom-in cosmological simulations of galaxies at z ~ 9-2. Our models were chosen to lie within similar-mass dark matter (DM) halos, log(M vir/M ⊙) ~ 11.65 ± 0.05, at z = 6, 4, and 2, in high- and low-overdensity environments. We apply two galactic wind feedback mechanisms for each model. All galaxies develop subkiloparsec stellar bars differing in their properties. We find that (1) the high-z bars form in response to various perturbations: mergers, close flybys, cold accretion inflows along the cosmological filaments, etc.; (2) these bars account for the large mass fraction of galaxies; (3) bars display large corotation-to-bar size ratios, are weaker compared to their low-redshift counterparts by measuring their Fourier amplitudes, and are very gas-rich; (4) their pattern speed does not exhibit monotonic decline with time owing to braking against DM, as at low z; (5) bar properties, including their stellar population (star formation rates and metal enrichment), depend sensitively on prevailing feedback; and (6) bars can weaken substantially during cosmological evolution, becoming weak oval distortions-hence bars are destroyed and reformed multiple times, unlike their low-z counterparts. In all cases, bars in our simulations have been triggered by interactions. In summary, not only do stellar bars appear to be a contemporary phenomenon, but based on increased frequency of mergers, flybys, and the strength of cold accretion flows at high z, we also expect them to be ubiquitous at redshifts ≳2-the epoch of rapid galaxy growth and larger stellar dispersion velocities.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2022
- DOI:
- 10.3847/1538-4357/ac779b
- arXiv:
- arXiv:2112.09718
- Bibcode:
- 2022ApJ...934...52B
- Keywords:
-
- Galactic abundances;
- Barred spiral galaxies;
- Hydrodynamical simulations;
- High-redshift galaxies;
- Galaxy evolution;
- Galaxy interactions;
- 2002;
- 136;
- 767;
- 734;
- 594;
- 600;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Astrophysical Journal (in press), 24 pages, 16 figures