http://arxiv.org/abs/2304.02904
We propose a new non-thermal dark matter which feebly couples to the standard model charged leptons.The feeble interactions allow it $(1)$ to freeze-in from standard model thermal bath with its relic density being a partial or a whole of the observed dark matter density and $(2)$ to radiatively decay to two photons in the dark matter mass ranges of order keV scale with lifetime larger than the age of Universe.These features make this non-thermal dark matter a realistic realization of dark matter with late-time decay as a solution to Hubble tension.We show that the $68\%$ CL best fit value of $H_{0}=68.3~(69.6)$ km s$^{-1}$Mpc$^{-1}$ compared to CMB+BAO (+LSS) data sets.We then use complimentary stellar cooling data to place stringent constraints on the parameter space.While the universal coupling scenario is excluded, the hierarchical coupling scenario can be tested by future observations on white dwarfs after a careful look into photon annihilation, Primakoff and Bremsstrahlung emission of the dark matter in various stellar systems.The viable parameter space may be linked to anomalies in future X-ray telescopes.
Z. Xu, R. Zhang and S. Zheng
Fri, 7 Apr 23
13/50
Comments: 19 pages, 7 figures