Superluminous supernova SN 2018ibb: Circumstellar shell and spectral effects

TL;DR

This paper investigates the observational effects of circumstellar gas around superluminous supernova SN 2018ibb, explaining spectral features and estimating the circumstellar shell mass through modeling and observations.

Contribution

It introduces a model explaining spectral features caused by circumstellar gas and estimates the shell mass, advancing understanding of superluminous supernova environments.

Findings

High velocity Fe II narrow absorptions explained by fragmented cold dense shell model.

Selective absorption in [O I] doublet due to radiation scattering in Si II lines.

Circumstellar shell mass estimated at about 0.14 solar masses.

Abstract

I explore observational effects of the cirsumstellar gas around superluminous supernova SN~2018ibb. High velocity Fe II narrow absorptions are reproduced in the model of fragmented cold dense shell. Unusual selective absorption in the emission doublet of [O I] is explained as an effect of the radiation scattering in Si II doublet lines in the supernova envelope.The strong emission of [O III] doublet at t_max + 565 days is proposed to originate from the supernova envelope, whereas its asymmetry is explained by the dust formation in the unshocked ejecta. Circumstellar interaction modeling combined with observational data suggests the cirsumstellar shell mass of about 0.14 Msun.