Subluminous type IIP SN 2024abfl as a result of a significantly low-energy Fe-core collapse

Abstract

We present extensive, well-sampled multiwavelength photometric and low-resolution optical spectroscopic observations of the low-luminosity Type IIP supernova (SN) SN 2024abfl. SN 2024abfl is found to be at the faintest end of Type IIP SNe with an unprecedented flat (0.1 mag 100 day─1) plateau evolution and a midplateau absolute magnitude of MV ≍ −13.8 mag, placing it among one of the faintest Type IIP SNe discovered to date. SN 2024abfl is adjacent to SN 2018zd in the same host NGC 2146. Using various SN distance measurement probes, we provide independent estimates of the debated distance to the host NGC 2146 (7─9 Mpc). The spectral evolution of SN 2024abfl is found to be similar to other SNe spectra of this subclass but with very narrow line profiles, indicating moderately low expansion velocities of the ejecta. Detailed 1D hydrodynamical modeling suggests a compact progenitor with an upper limit of 10 M⊙, fairly consistent with the directly detected progenitor estimates. It exploded with very low-energy 0.05 foe or less with a very low nickel mass of 0.003 M⊙, consistent with the observed parameters. These parameters provide important constraints on the nature of low-energy core-collapse explosions. We discuss possible progenitor scenarios and compare SN 2024abfl with other low-luminosity Type IIP SNe.