Quantify the fraction of r-process ejecta from neutron star mergers that enriches star-forming gas

Determine the fraction of r-process ejecta mass produced by neutron star mergers that becomes incorporated into star-forming interstellar gas within host galaxies, rather than remaining in the circumgalactic or intergalactic media, so that production estimates can be accurately compared to stellar r-process abundances.

Background

Neutron star mergers are directly observed to produce r-process material, but stellar abundance measurements are used to infer the Universe’s r-process budget. The paper emphasizes that not all r-process ejecta necessarily re-enters star-forming regions, leading to potential losses in the circumgalactic or intergalactic media. Quantifying how much ejecta enriches the star-forming interstellar medium is essential for connecting production to observed stellar abundances.