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JWST detection of heavy neutron capture elements in a compact object merger Published: 7/5/2023 11:19:23 AM Updated: 7/5/2023 11:19:23 AM

Paper abstract: The mergers of binary compact objects such as neutron stars and black holesare of central interest to several areas of astrophysics, including as theprogenitors of gamma-ray bursts (GRBs), sources of high-frequency gravitationalwaves and likely production sites for heavy element nucleosynthesis via rapidneutron capture (the r-process). These heavy elements include some of greatgeophysical, biological and cultural importance, such as thorium, iodine andgold. Here we present observations of the exceptionally bright gamma-ray burstGRB 230307A. We show that GRB 230307A belongs to the class of long-durationgamma-ray bursts associated with compact object mergers, and contains akilonova similar to AT2017gfo, associated with the gravitational-wave mergerGW170817. We obtained James Webb Space Telescope mid-infrared (mid-IR) imagingand spectroscopy 29 and 61 days after the burst. The spectroscopy shows anemission line at 2.15 microns which we interpret as tellurium (atomic massA=130), and a very red source, emitting most of its light in the mid-IR due tothe production of lanthanides. These observations demonstrate thatnucleosynthesis in GRBs can create r-process elements across a broad atomicmass range and play a central role in heavy element nucleosynthesis across theUniverse.