Cosmology2026-06-042 minarXiv:2606.06410expressAxions: How Small Can Their Share of Dark Matter Be?Dark matter is an invisible substance that reveals itself only through gravitational effects: it bends the light of distant galaxies, much like an unseen window that alters the path of light rays.Alex Laguë·Keir K. Rogers·Mathew S. Madhavacheril·J. Richard Bond·Erminia Calabrese·Mark J. Devlin·Jo Dunkley·Vera Gluscevic·Renée Hložek·Hidde T. Jense·Thibaut Louis·Frank J. Qu·Bernardita Ried Guachalla·Neelima Sehgal·Blake D. Sherwin·Suzanne T. Staggs·Alexander van Engelengravitational lensingAdam RiessAlan GuthAlbert Einsteinaxiondark matterdark photondark energygalaxy cluster👍👎☆SimplePopularAdvanced