JWST may solve a 20-year mystery behind a rule-breaking gamma-ray burst

Astronomers have identified the host galaxy of the 20-year-old gamma-ray burst GRB 061201, using the James Webb Space Telescope. The burst, detected in 2006, was previously classified as "hostless," meaning no galaxy was found at its location. The new study suggests the burst occurred in a distant galaxy, with the host galaxy's redshift estimated at z = 1.2. The team found a faint galaxy (G2) and a closer, fainter object (G3) in the same region, and their combined data ruled out G3 as a host candidate. The findings support the idea that the burst's energy output fits established patterns at this distance, and the implied merger rate lines up with gravitational-wave observations. The study concludes that the burst likely originated in a high-redshift galaxy, which is consistent with the observed afterglow behavior and energy output. The team stresses that a direct spectroscopic measurement of G2's distance is needed to confirm the result.

• The burst was classified as hostless and did not match established patterns of other short bursts.
• The team used JWST and Hubble to search for a more distant host-galaxy candidate.
• The redshift of G2 is estimated at z = 1.2, consistent with earlier indirect distance limits from the original afterglow data.
• The statistical "chance coincidence" probabilities for G2 and G3 are 18% and 43%, respectively.
• The team ruled out G3 as a host candidate and favored G2 as the true host.
• The study concludes that the burst's energy output and afterglow behavior are consistent with a high-redshift host galaxy.
• A direct spectroscopic measurement of G2's distance is needed to confirm the result.

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