2024A&A...683A.154M

Type II supernovae (SNe II) show growing evidence of an interaction with circumstellar material (CSM) surrounding their progenitor stars as a consequence of enhanced mass loss during the last years of the progenitor's life, although the exact mechanism is still unknown. We present an analysis of the progenitor mass-loss history of SN 2023ixf, a nearby SN II showing signs of an interaction. First, we calculated the early-time (< 19 days) bolometric light curve for SN 2023ixf based on the integration of the observed flux covering ultraviolet, optical and near-infrared bands, and black-body extrapolations for the unobserved flux. Our calculations detected the sudden increase to maximum luminosity and temperature, in addition to the subsequent fall, displaying an evident peak. This is the first time that this phase can be precisely estimated for a SN II. We used the early-time bolometric light curve of SN 2023ixf to test the calibrations of bolometric corrections against colours from the literature. In addition, we included the observations of SN 2023ixf into some of the available calibrations to extend their use to earlier epochs. A comparison of the observed bolometric light curve to SN II explosion models with CSM interaction suggests a progenitor mass-loss rate of Ṁ = 3 × 10^–3M_⊙ yr^–1 confined to 12 000 R_⊙ (∼8 × 10¹⁴ cm) and a wind acceleration parameter of β = 5. This model reproduces the early bolometric light curve, expansion velocities, and the epoch of disappearance of interacting lines in the spectra. This model indicates that the wind was launched ∼80 yr before the explosion. If the effect of the wind acceleration is not taken into account, the enhanced wind must have developed over the final months to years prior to the SN, which may not be consistent with the lack of outburst detection in pre-explosion images over the last ∼20 yr before explosion.