Unveiling the origin of the optical/UV emission from the Galactic ULX Swift J0243.6+6124 during its 2017-2018 giant outburst

J. Alfonso-Garzón, J. van den Eijnden, N. P. M. Kuin +8

From late September 2017 to February 2018, the Be X-ray binary (BeXB) Swift J0243.6+6124 underwent an unprecedently bright giant outburst. The reported X-ray luminosities were so h…