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Webb Confirms Most Distant Supernova Yet at z=7.3

The spectrum matches modern Type Ic-BL explosions, hinting at unexpectedly rapid early chemical enrichment.

Overview

  • An international campaign identified GRB 250314A after SVOM detected a burst on March 14, Swift rapidly localized it, and ESO’s VLT measured a redshift of 7.3, confirming a light-travel time exceeding 13 billion years.
  • Cosmic time dilation stretched the event, enabling JWST to target the site on July 1, 2025 and capture the supernova near its infrared peak.
  • Spectral analysis shows a close match to Type Ic-BL supernovae observed in the nearby universe rather than the distinct signatures expected from first-generation, metal-free stars.
  • Webb resolved a low-mass, star-forming host galaxy consistent with systems from the epoch of reionization.
  • Two peer-reviewed papers in Astronomy & Astrophysics detail the observations and set a new benchmark that will guide searches for additional early-universe supernovae.