1704.08254
On the deuterium abundance and the importance of stellar mass loss in the interstellar and intergalactic medium
van de Voort, Quataert, Faucher-Giguére, Keres, Hopkins, Chan, Feldmann, Hafen
Quantify the gas-phase abundance of D in cosmological zoom-in simulations from the FIRE project. The cosmic D fraction decreases with time, because mass lost from stars is D-free. At low metallicity, the simulations confirm that the D abundance is very close to the primordial value. The D abundance decreases towards higher metallicity, with very small scatter between the D and O abundance. Compare the sims to existing high-z observations in order to determine a primordial D fraction of (2.549±0.033)e-5 and stress that future observations at higher metallicity can also be used to constrain this value. At fixed metallicity, the D fraction decreases slightly with decreasing z, due to the increased importance of mass loss from intermediate-mass stars. Find that the evolution of the average D fraction in a galaxy correlates with its star formation history. The simulations are consistent with observations of the MW's ISM: the D fraction at the solar circle is 83-92% of the primordial D fraction. Use the sims to make predictions for future observations. In particular, the D abundance is lower at smaller galactocenetric radii and in higher mass galaxies, showing that stellar mass loss is more important for fueling SF in these regimes (and can even dominate). Gas accreting onto galaxies has a D fraction above that of the galaxies' ISM, but below the primordial fraction, because it is a mix of gas accreting from the IGM and gas previously ejected or stripped from galaxies.
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