Strongly Coupled Cosmologies

Models including an energy transfer from CDM to DE were widely considered in the literature, namely to allow DE a significant high-zdensity. Strongly Coupled cosmologies assume a much larger coupling between DE and CDM, together with an uncoupled warm DM component, the role of Cbeing mostly restricted to radiative eras. This allows us to preserve small scale fluctuations even if the warm particle is quite light, O(100 eV). Linear theory shows full agreement between these cosmologies and ΛCDM on supergalactic scales; e.g., CMB spectra are identical. Simultaneously, simulations show that they ease problems related to the properties of MW satellites and cores in dwarfs. While opening new perspectives on early black hole formation and possibly leading towards unificating DE and inflationary fields, the critical prediction of SC cosmologies is a sterile neutrino or gravitino of mass∼ 100 eV.