The Chemical Residue of a White Dwarf-dominated Galactic Halo

Halo initial mass functions (IMFs) heavily biased toward white dwarf (WD) precursors (i.e., ~1-8 M☉) have been suggested as a suitable mechanism for explaining microlensing statistics along the line of sight to the Large Magellanic Cloud. Such IMFs can apparently be invoked without violating the observed present-day WD luminosity function. By employing a simple chemical evolution argument, we demonstrate that reconciling the observed halo Population II dwarf abundances (i.e., [C, N/O] ≈ -0.5) with that expected from the postulated “WD-heavy” IMF (i.e., [C, N/O] ≳ +0.5) is difficult.

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