Searching for an additional high-energy component in Fermi-LAT GRB afterglows Xin-Bo He, Pak-Hin Thomas Tam, Guang-Bo Long, Partha Sarathi Pal, Yong Zhang and Li-Jun Zhang A&A, 657 (2022) A111 Published online: 20 January 2022 DOI: 10.1051/0004-6361/202040039