Detection of an unidentified soft X-ray emission feature in NGC 5548 Liyi Gu, Junjie Mao, Jelle S. Kaastra, Missagh Mehdipour, Ciro Pinto, Sam Grafton-Waters, Stefano Bianchi, Hermine Landt, Graziella Branduardi-Raymont, Elisa Costantini et al. (10 more) A&A, 665 (2022) A93 Published online: 15 September 2022 DOI: 10.1051/0004-6361/202244075