Constraining Dust Formation in the Superluminous Supernova 2017gci with JWST Observations
October 2026 • 2026ApJ..1010..169G
Abstract • We present JWST/MIRI observations of the Type I superluminous supernova (SLSN) 2017gci obtained over 2000 rest-frame days after the supernova (SN) exploded, which represent the latest phase images taken of any known SLSN to date. We find that archival Wide-field Infrared Survey Explorer (WISE) detections of SN 2017gci taken 70--200 days after explosion are most likely explained by an IR dust echo from a ~10-4 M⊙ shell of preexisting dust, as opposed to freshly formed dust. New JWST observations reveal mid-infrared emission at the position of SN 2017gci; however, the flux level and spatial offset indicate that this emission is most likely dominated by the host galaxy. We therefore derive upper limits from these observations to constrain dust emission at late times. Radiative transfer modeling of carbonaceous dust shows that warm optically thin dust masses up to 0.18 M⊙ are excluded at the 3σ confidence level. However, substantially larger dust masses cannot be ruled out if the dust is optically thick. Infrared detections of other SLSNe have suggested that SLSNe may be highly efficient dust producers. While our constraints are insufficient to determine the total dust yield of SN 2017gci, they indicate that any late-time dust emission must either be modest compared to the most dust-rich SNe or arise from dust that is optically thick. A larger sample of deep infrared observations will be required to determine whether SLSNe are significant contributors to cosmic dust production.
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