Optical images of the Kerr–Sen black hole and thin accretion disk Pei Wang, Sen Guo, Li-Fang Li, Zhan-Feng Mai, Bo-Feng Wu, Wen-Hao Deng and Qing-Quan Jiang Eur. Phys. J. C, 85 7 (2025) 747 Published online: 07 July 2025 DOI: 10.1140/epjc/s10052-025-14441-1