The Atacama Cosmology Telescope: Probing new signatures of ultralight axions with gravitational lensing
This paper presents the strongest constraints to date on ultralight axions in the mass range 10−26 to 10−24.5 eV using gravitational lensing data from Planck, ACT, and SPT-3G, finding that such axions can constitute at most a few percent of dark matter while noting a tentative 2.1σ preference for their existence at 10−24.5 eV that warrants further investigation.
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, Bernardit (…)2026-06-05⚛️ gr-qc