Multiple Channels for Nitrogen Pollution by Metal-enriched Supermassive Stars and Implications for GN-z11

Abstract

GN-z11 is an unusually luminous high-redshift galaxy that was recently observed to have strong nitrogen lines while at the same time lacking traditional signatures of active galactic nucleus activity. These observations have been interpreted as a supersolar nitrogen abundance, which is challenging to explain with standard stellar evolution and supernova enrichment. We present simulations of four models of metal-enriched supermassive stars after the zero age main sequence, which produce supersolar nitrogen consistent with the observations of GN-z11. We then show that the most-massive model ends its life in a violent explosion that results in even greater nitrogen pollution.