Luminous fast and blue optical transients (LFBOTs) are a recently-found enigmatic population of extragalactic transients. Their extreme properties (e.g., high optical and UV luminosities, short-timescale, strong X-ray and radio emission) indicate that they are powered by a ‘central engine’, i.e. a highly active compact object (probably a black hole; BH). A recent discovery of a bright and minute-timescale optical flaring activity in the late phase of LFBOT AT2022tsg has no precedent, opening up a possibility of directly testing the central hypothesis of the LFBOTs as the central engine-powered explosive transients. We propose to perform ToO observations to search for a short-timescale flaring activity, i.e., the second example, for a next well-observed LFBOT with Subaru/FOCAS (i.e., confirmation of the central engine as the immediate goal), with a variety of implications on the central engine either for detection (duty cycle, BH mass) or non-detection (frequency/rarity, geometry and the origin of diversity).
This document was translated from LATEX by HEVEA.