The Near-infrared Echo from SN 2023xgo: Evidence for a Massive Presupernova Eruption in a Type Ibn/Icn Supernova

We present near-infrared (NIR) and optical observations and analysis of the Type Ibn/Icn supernova (SN) 2023xgo, spanning the period from 2 to 100 days past explosion. A comparison of the NIR light curves and color evolution with those of other Type Ibn SNe reveals prominent NIR excess persisting from 15 to 100 days. The spectral energy distribution is well explained by a combination of a hot blackbody component and a carbon dust model. The dust temperature remained relatively constant at T = 1600 ± 100 K up to t = 60 days. The estimated dust mass is ∼1.2 × 10 −4 M ⊙ . Based on the SN emission of 10 42 erg s −1 at peak luminosity, the evaporation radius is estimated to be 1.2 × 10 16 cm, consistent with the expectation from light travel time. The dust shell is located outside the shocked, cool dense shell at the position of 7.6 × 10 14 cm. It suggests that the observed NIR excess originates from preexisting circumstellar (CS) dust. Considering a typical dust-to-gas mass ratio, the CS gas mass is estimated to be ≃10 −2 M ⊙ , implying a high mass-loss rate of ∼0.1 M ⊙ yr −1 from either a low-mass helium star progenitor with a binary interaction, or maybe a massive Wolf–Rayet star that experienced a significant eruption.