The search for failed supernovae with the Large Binocular Telescope: the failed SN fraction and new candidates with 11 yr of data

We present updated results of the Large Binocular Telescope Survey for Failed Supernovae. We re-discover the failed supernova (SN) candidate N6946-BH1 as well as two new potential candidates, N4736-OC1 and M101-OC1. While N4736-OC1 is most likely a post-AGB star undergoing an extreme dimming episode, the blue supergiant (BSG) progenitor of M101-OC1 does not show evidence for dust obscuration despite significant optical dimming, making it a strong candidate for a failed SN, though other scenarios are considered. In addition to presenting these two new candidates, we present updated estimates of the failed SN fraction. We find that with assuming one detected failed SN, f = 0.16^+0.23_-0.12 with a 90 per cent confidence limit.