• High-energy photons produced in gamma-ray burst jets from collapsed stars can dissolve the star's outer layers into free neutrons.
• This process creates conditions for the rapid neutron-capture process (r-process), leading to the formation of heavy elements like uranium and plutonium.
• The proposed framework helps explain the origination of kilonovae associated with long-duration gamma-ray bursts.

A new study published in the Astrophysical Journal proposes a novel mechanism for the creation of heavy elements in the universe. Researchers suggest that as massive stars collapse into black holes, powerful jets of high-energy photons can dissolve the star's outer layers into free neutrons. These neutrons then participate in the rapid neutron-capture process (r-process), leading to the synthesis of heavy elements such as uranium and plutonium. This process may also explain the kilonovae observed alongside long-duration gamma-ray bursts.

• What: High-energy photons from collapsing stars interact with atomic nuclei, transmuting protons to neutrons and dissolving nuclei into nucleons, powering the r-process and forming heavy elements.
• Who: Dr. Matthew Mumpower (Los Alamos National Laboratory) and his team.
• When: The process occurs during the collapse of massive stars into black holes, specifically when the black hole is spinning fast enough to launch a powerful jet.
• Where: Within the collapsing star and the surrounding cocoon of material created by the jet.

The study provides a new perspective on the origins of heavy elements in the universe, proposing a dynamic mechanism for neutron production during star collapses. This challenges previous assumptions that neutrons must pre-exist in sufficient quantities for the r-process to occur. The framework also offers a potential explanation for the observed connection between kilonovae and long-duration gamma-ray bursts, linking these phenomena to the formation of heavy elements. Further research, including simulations of the high-energy jet framework, is needed to validate and refine this model.

"The creation of heavy elements such as uranium and plutonium necessitates extreme conditions. There are only a few viable yet rare scenarios in the cosmos where these elements can form, and all such locations need a copious amount of neutrons. We propose a new phenomenon where those neutrons don’t pre-exist but are produced dynamically in the star."

"The jet blasts through the star ahead of it, creating a hot cocoon of material around the jet, like a freight train plowing through snow."

The study presents a compelling new model for the formation of heavy elements, linking the collapse of massive stars to the dynamic production of neutrons and the r-process. This framework not only sheds light on the origins of elements like uranium and plutonium but also offers a potential explanation for kilonovae associated with long-duration gamma-ray bursts. While further research is needed to validate these findings, the study represents a significant step forward in our understanding of nucleosynthesis and the evolution of the universe.