He abundances in disc galaxies -- I. Predictions from cosmological chemodynamical simulations

Vincenzo, Fiorenzo; Miglio, Andrea; Kobayashi, Chiaki; Ted Mackereth, J.; Montalban, Josefina

Abstract

We investigate how the stellar and gas-phase He abundances evolve as functions of time within simulated star-forming disc galaxies with different star formation histories. We make use of a cosmological chemodynamical simulation for galaxy formation and evolution, which includes star formation, as well as energy and chemical enrichment feedback from asymptotic giant branch stars, core-collapse supernovae, and Type Ia supernovae. The predicted relations between the He mass fraction, $Y$, and the metallicity, $Z$, in the interstellar medium of our simulated disc galaxies depend on the past galaxy star formation history. In particular, $dY/dZ$ is not constant and evolves as a function of time, depending on the specific chemical element that we choose to trace $Z$; in particular, $dY/dX_{\text{O}}$ and $dY/dX_{\text{C}}$ increase as functions of time, whereas $dY/dX_{\text{N}}$ decreases. In the gas-phase, we find negative radial gradients of $Y$, due to the inside-out growth of our simulated galaxy discs as a function of time; this gives rise to longer chemical enrichment time scales in the outer galaxy regions, where we find lower average values for $Y$ and $Z$. Finally, by means of chemical evolution models, in the galactic bulge and inner disc, we predict steeper $Y$ versus age relations at high $Z$ than in the outer galaxy regions. We conclude that, for calibrating the assumed $Y$-$Z$ relation in stellar models, C, N, and C+N are better proxies for the metallicity than O, because they show steeper and less scattered relations.

Citation

Vincenzo, F., Miglio, A., Kobayashi, C., Ted Mackereth, J., & Montalban, J. (2019). He abundances in disc galaxies -- I. Predictions from cosmological chemodynamical simulations. Astronomy and Astrophysics, 630, Article A125. https://doi.org/10.1051/0004-6361/201935886

• Journal Article Type: Article
• Acceptance Date: Jul 24, 2019
• Online Publication Date: Oct 3, 2019
• Publication Date: Oct 3, 2019
• Deposit Date: Mar 12, 2022
• Publicly Available Date: Mar 31, 2022
• Journal: Astronomy and Astrophysics
• Print ISSN: 0004-6361
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 630
• Article Number: A125
• DOI: https://doi.org/10.1051/0004-6361/201935886
• Keywords: Astrophysics of Galaxies
• Public URL: https://hull-repository.worktribe.com/output/3946252