Emission lines due to ionizing radiation from a compact object in the remnant of Supernova 1987A

The nearby Supernova 1987A was accompanied by a burst of neutrino emission, which indicates that a compact object (a neutron star or black hole) was formed in the explosion. There has been no direct observation of this compact object. In this work, we observe the supernova remnant with JWST spectroscopy, finding narrow infrared emission lines of argon and sulfur. The line emission is spatially unresolved and blueshifted in velocity relative to the supernova rest frame. We interpret the lines as gas illuminated by a source of ionizing photons located close to the center of the expanding ejecta. Photoionization models show that the line ratios are consistent with ionization by a cooling neutron star or a pulsar wind nebula. The velocity shift could be evidence for a neutron star natal kick. Editor’s summary The nearby supernova SN 1987A was visible to the naked eye, and its evolution has been observed over the ensuing decades. The explosion is thought to have produced a neutron star or black hole, but none has been directly detected. Fransson et al. observed a remnant of SN 1987A using near- and mid-infrared integral field spectroscopy. They identified emission lines of ionized argon that appear only near the center of the remnant. Photoionization models show that the line ratios and velocities can be explained by ionizing radiation from a neutron star illuminating gas from the inner parts of the exploded star. —Keith T. Smith Infrared spectroscopy of the supernova remnant SN 1987A indicates that it contains a neutron star.