Raising the Optical Depth to Reionization with Dark Matter Decay
DESI DR2 baryon acoustic oscillation (BAO) measurements have sharpened a discrepancy with cosmic microwave background (CMB) inferences that can be recast as a preference for $\tau_{\rm reio}\simeq0.09$, above the $\simeq0.06$ inferred from large-scale CMB polarization. We test whether electromagnetic energy injection f...