Can neutron star mergers alone explain r-process enhancements?

Determine whether neutron star mergers, acting as the sole astrophysical site, can fully account for the observed diversity of r-process element enhancements across astrophysical environments, or whether additional sites are required.

Background

Neutron star mergers have strong observational support as r-process sites following GW170817 and its kilonova. However, multiple astrophysical sites have been proposed for r-process production and observations show a range of enhancement levels in different stars and systems. The paper highlights that it remains unresolved whether neutron star mergers by themselves can reproduce this variety, motivating targeted theoretical and observational tests.

References

However, whether NSMs alone can fully account for various enhancements of r-process elements remains an open question.

— The Actinide-Boost Star LAMOST J122216.85-063345.2: A Detailed R-process Abundance Study with Gemini-S/GHOST  (2603.29246 - Jeong et al., 31 Mar 2026) in Section 1, Introduction

The interpretation of the AT2017gfo spectra has not yet reached consensus regarding whether neutron-star mergers can account for the full range of $r$-process elements observed in the solar system.

— Supernova nucleosynthesis: a review  (2609.16584 - Zha et al., 15 Sep 2026) in Table 1, footnote 1