In:
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 501, No. 4 ( 2021-01-20), p. 5121-5134
Kurzfassung:
We explore the origin of stellar metallicity gradients in simulated and observed dwarf galaxies. We use FIRE-2 cosmological baryonic zoom-in simulations of 26 isolated galaxies as well as existing observational data for 10 Local Group dwarf galaxies. Our simulated galaxies have stellar masses between 105.5 and 108.6 M⊙. Whilst gas-phase metallicty gradients are generally weak in our simulated galaxies, we find that stellar metallicity gradients are common, with central regions tending to be more metal-rich than the outer parts. The strength of the gradient is correlated with galaxy-wide median stellar age, such that galaxies with younger stellar populations have flatter gradients. Stellar metallicty gradients are set by two competing processes: (1) the steady ‘puffing’ of old, metal-poor stars by feedback-driven potential fluctuations and (2) the accretion of extended, metal-rich gas at late times, which fuels late-time metal-rich star formation. If recent star formation dominates, then extended, metal-rich star formation washes out pre-existing gradients from the ‘puffing’ process. We use published results from ten Local Group dwarf galaxies to show that a similar relationship between age and stellar metallicity-gradient strength exists among real dwarfs. This suggests that observed stellar metallicity gradients may be driven largely by the baryon/feedback cycle rather than by external environmental effects.
Materialart:
Online-Ressource
ISSN:
0035-8711
,
1365-2966
DOI:
10.1093/mnras/staa3958
Sprache:
Englisch
Verlag:
Oxford University Press (OUP)
Publikationsdatum:
2021
ZDB Id:
2016084-7
SSG:
16,12
