Merging binary black holes formed through double-core evolution Y. Qin, R.-C. Hu, G. Meynet, Y. Z. Wang, J.-P. Zhu, H. F. Song, X. W. Shu and S. C. Wu A&A, 671 (2023) A62 Published online: 06 March 2023 DOI: 10.1051/0004-6361/202244712