Photometric and spectroscopic studies of type Ic supernovae SN 2020akf and SN 2021mxx

Abstract

We present a comprehensive analysis of optical photometry and medium-resolution spectroscopy for Type Ic supernovae (SNe) SN 2020akf and SN 2021mxx. Our study covers the evolution of SN 2020akf from −5 to 109 days and SN 2021mxx from −3 to 115 days relative to their B-band maximum. Their peak quasi-bolometric luminosities are estimated at logLbolmax=42.37±0.02 erg s−1 and 42.21 ± 0.02 erg s−1, respectively. The velocities of ejecta, derived from the Fe II λ5169 line at maximum light, are approximately 15,000 km s−1 for SN 2020akf and about 10,000 km s−1 for SN 2021mxx, which are consistent with those observed in other Type Ic SNe. Using the semianalytical Arnett model, we estimate that SN 2020akf has a kinetic energy of Ek=6.33−0.62+0.68×1051 erg and an ejected mass of M ej=4.71−0.46+0.50 M⊙, while for SN 2021mxx we get Ek=0.54−0.12+0.08×1051 erg and M ej=0.90−0.18+0.14 M⊙. The mass of 56Ni synthesized in the explosion is estimated at 0.10 ± 0.02 M⊙ for SN 2020akf and 0.05 ± 0.01 M⊙ for SN 2021mxx. The metallicities of the host galaxies near the SN regions are ∼0.81 Z⊙ for SN 2020akf and ∼0.76 Z⊙ for SN 2021mxx, where Z⊙ indicates solar metallicity. Our detailed analysis suggests that SN 2020akf falls into the category of a transitional Type Ic SN, having spectral properties between normal and broad-line Type Ic SNe, while SN 2021mxx is a normal Type Ic SN with an extremely low value of the Mej/Ek ratio.