JWST unveils a dust-obscured supernova associated with a gamma-ray burst

@misc{schneider2026jwst,
  title = {{JWST unveils a dust-obscured supernova associated with a gamma-ray burst}},
  author = {B Schneider and A.J Levan and N Sarin and N.A Rakotondrainibe and B.P Gompertz and V Buat and J.T Palmerio and D.B Malesani and A de Ugarte Postigo and A Martin-Carrillo and A Rossi and V d'Elia and M de Pasquale and D Hartmann and P Jakobsson and E Le Floc'H and P O'Brien and E Pian and G Pugliese and A Raidani and R Salvaterra and J Sollerman and N.R Tanvir and S.D Vergani and D Watson},
  howpublished = {HAL},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.35697},
  eprint = {2609.35697},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05842234v1},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - JWST unveils a dust-obscured supernova associated with a gamma-ray burst
AU  - B Schneider
AU  - A.J Levan
AU  - N Sarin
AU  - N.A Rakotondrainibe
AU  - B.P Gompertz
AU  - V Buat
AU  - J.T Palmerio
AU  - D.B Malesani
AU  - A de Ugarte Postigo
AU  - A Martin-Carrillo
AU  - A Rossi
AU  - V d'Elia
AU  - M de Pasquale
AU  - D Hartmann
AU  - P Jakobsson
AU  - E Le Floc'H
AU  - P O'Brien
AU  - E Pian
AU  - G Pugliese
AU  - A Raidani
AU  - R Salvaterra
AU  - J Sollerman
AU  - N.R Tanvir
AU  - S.D Vergani
AU  - D Watson
PY  - 2026
DA  - 2026/09/28
PB  - HAL
DO  - 10.48550/arxiv.2609.35697
UR  - https://hal.science/hal-05842234v1
AB  - Recent observations have challenged the duration-based classification of gamma-ray bursts (GRBs), making the detection of an associated supernova (SN) or kilonova crucial for conclusively identifying their progenitors. We investigate the origin of GRB 240825A at z=0.659, whose prompt emission gave conflicting indications of a merger or collapsar origin and for which no SN was detected in deep ground-based observations. We analyze JWST/NIRSpec observations obtained 66.5 days (40.1 days in the rest frame) after the burst. We identify a SN signal using a pixel-by-pixel decomposition of the 2D spectrum and isolate it by jointly modeling the host and transient emission. We constrain the line of sight extinction from the afterglow spectral energy distribution and characterize the host through broadband photometry and nebular emission lines. Despite a dusty line of sight (A_V=1.37±0.08 mag), with tentative evidence of a 2175 Å bump, and a bright host galaxy (M_B=−20.5 AB mag), we identify a point-like source at the GRB position with broad spectral features similar to those of SN 1998bw. The SN contributes ∼10-15% of the NIRSpec flux and would contribute only ∼1% of the total flux in a ground-based optical image at the same epoch. Its extinction-corrected luminosity is comparable to SN 1998bw, although it remains sensitive to the host subtraction and template assumptions. The host is an extended, dusty, star-forming galaxy with log(M_⋆/M_⊙)=10.12±0.05, SFR =5.88±1.60 M_⊙ yr^−1, and a super-solar metallicity of 12+log(O/H)=8.87±0.04, above the metallicity typically observed for collapsar GRB hosts. The detection of a dust-obscured SN firmly establishes the massive-star origin of GRB 240825A and shows that JWST can uncover SNe in dusty, chemically enriched environments that were previously largely inaccessible.
ER  -