An IXPE-led X-Ray Spectropolarimetric Campaign on the Soft State of Cygnus X-1: X-Ray Polarimetric Evidence for Strong Gravitational Lensing by Steiner, JF, Nathan, E, Hu, K, Krawczynski, H, Dovčiak, M, Veledina, A, Muleri, F, Svoboda, J, Alabarta, K, Parra, M, Bhargava, Y, Matt, G, Poutanen, J, Petrucci, P, Tennant, AF, Baglio, MC, Baldini, L, Barnier, S, Bhattacharyya, S, Bianchi, S, Brigitte, M, Cabezas, M, Cangemi, F, Capitanio, F, Rhodes, L