Type IIP SN 2024bch: Hydrodynamic model, shock breakout, and circumstellar interaction

Abstract

The well-observed type IIP SN 2024bch with the short plateau is shown to be an outcome of the red supergiant explosion with the presupernova mass of 14-15 Msun, the explosion energy of 2x10^{51} erg, and presupernova radius of 1250 Rsun. The early gamma-ray escape demonstrated by the radioactive tail is due to the large Ni-56 extension up to 7400 km/s. The early-time spectral evolution indicates the presence of the circumstellar dense confined envelope with the mass of 0.003-0.006 Msun within 6x10^{14} cm. The deceleration of the outermost ejecta implies the wind with the mass-loss rate of about 6x10^{-4} Msun/yr. The inferred mass-loss rate is by one-two order larger compared to most of type IIP supernovae, but comparable to the wind of type IIL SN 1998S. The asymmetry of the broad H-alpha component on day 144 powered by the circumstellar interaction is the outcome of the Thomson scattering and absorption in the Paschen continuum in the unshocked ejecta.