Which site dominates the r-process inventory of the Milky Way? · revision history

Revision 2

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Title
Which site dominates the r-process inventory of the Milky Way?
Plain
Neutron-star mergers, rare collapsing stars and flares from magnetars can all make r-process elements; their shares are unknown.
Precise
Determine the fractional contributions of neutron-star mergers (including neutron star-black hole), collapsars and magnetorotational supernovae, and magnetar giant flares to the Galactic r-process mass. Constraints: binary neutron star merger rate from gravitational waves ($\sim 10\text{ to }1700\,\mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$), ejecta per event ($\sim 0.01\text{ to }0.05\,M_{\mathrm{sun}}$), the $[\mathrm{Eu}/\mathrm{Fe}]$ versus $[\mathrm{Fe}/\mathrm{H}]$ trend and its scatter in metal-poor stars, and Pu-244 in deep-sea crusts. Answer: fractions with uncertainties.
Settled by
A tighter merger rate and kilonova yield sample from gravitational-wave events, together with direct detection of r-process signatures from collapsars.
Kind
phenomenon
Answer type
identification
References
(empty)
Literature status
contested
Status note · changed
Revision 1: 2025: delayed MeV emission after the 2004 SGR 1806-20 giant flare was interpreted as radioactive decay of about $1e-6\,M_{\mathrm{sun}}$ of fresh r-process matter, adding magnetar flares as a minor site.
Revision 2: 2025: delayed MeV emission after the 2004 SGR 1806-20 giant flare was interpreted as radioactive decay of about $10^{-6}\,M_{\mathrm{sun}}$ of fresh r-process matter, adding magnetar flares as a minor site.
Posed since
1957

Decisions