More luminous red novae that require jets

TL;DR

This paper challenges jet-less models for luminous red novae, providing evidence that jets are crucial in powering and shaping these transients, especially during binary interactions like grazing envelope evolution.

Contribution

It demonstrates that jet-less common envelope models cannot explain certain properties of LRNe, emphasizing the importance of jets in their evolution.

Findings

Jet-less models fail to reproduce observed properties of LRNe.

Mass ejection episodes suggest incomplete common envelope evolution.

Jets likely play a major role in powering and shaping LRNe ejecta.

Abstract

I study two intermediate luminosity optical transients (ILOTs) classified as luminous red novae (LRNe) and argue that their modeling with a common envelope evolution (CEE) without jets encounters challenges. LRNe are ILOTs powered by violent binary interaction. Although popular in the literature is to assume a CEE is the cause of LRNe, I here repeat an old claim that many LRNe are powered by grazing envelope evolution (GEE) events; the GEE might end in a CEE or a detached binary system. I find that the LRN AT 2021biy might have continued to experience mass ejection episodes after its eruption and, therefore, might not suffered a full CEE during the outburst. This adds to an earlier finding that a jet-less model does not account for some of its properties. I find that a suggested jet-less CEE model for the LRN AT 2019zhd does not reproduce its photosphere radius evolution. These results that challenge jet-less models of two LRNe strengthen a previous claim that jets play major roles in powering ILOTs and shaping their ejecta and that in many LRNe, the more compact companion launches the jets during a GEE.