UC Irvine

We report cosmological results from the Dark Energy Spectroscopic Instrument (DESI) measurements of baryon acoustic oscillations (BAO) when combined with recent data from the Atacama Cosmology Telescope (ACT). By jointly analyzing ACT and data and applying conservative cuts to overlapping multipole ranges, we assess how different dataset combinations affect consistency with DESI. While ACT alone exhibits a tension with DESI exceeding within the model, this discrepancy is reduced when ACT is analyzed in combination with . For our baseline DESI DR2 likelihood combination, the preference for evolving dark energy over a cosmological constant is about , increasing to over with the inclusion of type Ia supernova data. While the dark energy results remain quite consistent across various combinations of and ACT likelihoods with those obtained by the DESI collaboration, the constraints on neutrino mass are more sensitive, ranging from in our baseline analysis, to (95% confidence level) in the CMB likelihood combination chosen by ACT when imposing the physical prior .