AT 2018lqh: Black Hole Born from a Rotating Star?

Recently an intriguing transient, AT 2018lqh, with only a day-scale duration and a high luminosity of 7 × 1042 erg s−1, was 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 ∼30 M⊙ 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.