Extragalactic archaeology with the C, N, and O chemical abundances

TL;DR

This paper models the evolution of C, N, and O abundances in galaxy interstellar media using hydrodynamical simulations, revealing new trends influenced by failed supernovae and inhomogeneous enrichment, with implications for understanding galaxy star formation histories.

Contribution

It introduces a novel simulation approach incorporating failed supernovae to predict detailed CNO abundance trends over cosmic time.

Findings

N/O--O/H trend increases with failed supernovae

Flat N/O--O/H trends at high redshift due to inhomogeneous enrichment

CNO ratios evolve with star formation activity and stellar yields

Abstract

We predict how the C, N, and O abundances within the interstellar medium of galaxies evolve as functions of the galaxy star formation history (SFH). We adopt a hydrodynamical cosmological simulation, focusing on three star-forming disc galaxies with different SFHs. By assuming failed supernovae, we can predict an increasing trend of the gas-phase N/O--O/H abundance diagram, which was not produced in our previous simulations without failed supernovae. At high redshifts, contrary to the predictions of classical chemical evolution models with instantaneous mixing approximation, we find almost flat trends in the N/O--O/H diagram, which are due to the contribution of intermediate-mass stars together with an inhomogeneous chemical enrichment. Finally, we also predict that the average N/O and C/O steadily increase as functions of time, while the average C/N decreases, due to the mass and metallicity dependence of the yields of asymptotic giant branch stars; such variations are more marked during more intense star formation episodes. Our predictions on the CNO abundance evolution can be used to study the SFH of disc galaxies with the James Webb Space Telescope.