One of the major long-standing questions in astrophysics is the origin of the elements. The heavy elements in the Universe are thought to be created via neutron-capture processes (either via the “slow” or “rapid” processes). The rapid (“r-process”) occurs in extreme events such as the merger of two neutron stars and may be a main formation pathway for elements such as uranium, gold, and xenon. In addition to neutron star mergers, collapsars (a potential explanation for super-luminous supernovae) have been proposed as sites of r-process formation of heavy elements. In “Radio Constraints on r-process Nucleosynthesis by Collapsars” (Lee+) we search a variety of wide-area radio surveys to look for radio afterglows of gamma ray bursts in an attempt to identify possible collapsar events. We did not find any likely candidates, suggesting that collapsars are not the dominant sites of heavy element formation via the r-process.
The paper has been submitted for publication and a preprint is available at the above link.