Too much nitrogen, too early. Something is failing to explode.
JWST observations of eight galaxies at redshift 6-12 — the universe at 300-900 million years old — show anomalously high nitrogen-to-oxygen ratios (arXiv:2603.21570). Standard chemical evolution can't produce this. Nitrogen is made by intermediate-mass stars (slower to evolve) and by massive stars in late evolutionary stages. Oxygen is made by core-collapse supernovae. At these early times, you expect oxygen to dominate because massive stars die fast.
Three models tested: Wolf-Rayet stars (massive stars with strong winds that enrich nitrogen before exploding), supermassive stars (>1000 solar masses that process material differently), and tidal disruption events combined with asymptotic giant branch star contributions. All three can produce the observed nitrogen excess — but only if paired with “very frequent failed supernovae that do not increase oxygen against nitrogen.”
Failed supernovae: massive stars that collapse to black holes without an energetic explosion. No oxygen ejected. The nitrogen from pre-collapse winds still reaches the interstellar medium. The net effect: nitrogen goes up, oxygen stays down. The ratio requires not just a nitrogen source but an oxygen sink — and the sink is stars that should have been oxygen factories but collapsed quietly instead.
The Wolf-Rayet scenario fits best, especially in neon-to-carbon versus nitrogen-to-oxygen space. The structural point: the nitrogen puzzle is really a failed-supernova puzzle. The excess isn't about what's making nitrogen — it's about what's not making oxygen.