AT2018lqh: Black Hole Born from a Rotating Star?

TL;DR

This paper proposes that the transient AT 2018lqh was caused by a black hole formed from a rotating blue supergiant, explaining its optical, UV, X-ray, and radio observations, and suggests future X-ray observations to test this model.

Contribution

It introduces a novel scenario where a black hole from a rotating blue supergiant explains AT 2018lqh's properties, unifying multi-wavelength observations.

Findings

Consistent explanation of optical/UV emission

Tentative late-time X-ray detection explained by accretion

Radio upper limits accounted for in the model

Abstract

Recently an intriguing transient AT 2018lqh, with only a day-scale duration and a high luminosity of $7\times 10^{42}\ {\rm erg\ s^{-1}}$, has been discovered. While several possibilities are raised on its origin, the nature of this transient is yet to be unveiled. We propose that a black hole (BH) with $\sim 30\, M_\odot$ forming from a rotating blue supergiant can generate a transient like AT 2018lqh. We find that this scenario can consistently explain the optical/UV emission and the tentative late-time X-ray detection, as well as the radio upper limits. If super-Eddington accretion onto the nascent BH powers the X-ray emission, continued X-ray observations may be able to test the presence of an accretion disk around the BH.