Within the framework of Unimodular Gravity, we consider non-gravitational interactions between dark matter and dark energy. Particularly, we describe such interactions in the dark sector by considering diffusion models that couple the cold dark matter fluid with the dark energy component, where the latter has the form of a variable cosmological “constant”. For the first time, we solve the cosmological evolution of these models from the radiation dominated era to the present day. We show how the diffusion processes take place by analyzing the cosmological evolution of the energy density parameters ${\Omega }_{cdm}$ and ${\Omega }_{\Lambda }$, as well as that of the Hubble parameter. Finally, we perform the statistical analysis, imposing constraints on the diffusion parameters, by using data from Planck 2018, SH0ES, Pantheon, and H0LICOW collaborations. We found that cosmological diffusion models in the framework of Unimodular Gravity can ease the current tension in the value of $H_0$. We also show that the very far future cosmological evolution for all diffusion models is eternally accelerating without future singularities.

在单模重力的框架内，我们考虑了暗物质和暗能量之间的非引力相互作用。特别是，我们通过考虑将冷暗物质流体与暗能量成分耦合的扩散模型来描述暗区中的这种相互作用，暗能量成分具有可变宇宙学“常数”的形式。我们第一次解决了这些模型从辐射主导时代到今天的宇宙学演变。通过分析能量密度参数的宇宙演化，我们展示了扩散过程是如何发生的${\Omega }_{Cd米}$ 和 ${\Omega }_{\Lambda }$，以及Hubble参数的值。最后，我们使用来自Planck 2018，SH0ES，Pantheon和H0LICOW合作的数据进行统计分析，并对扩散参数施加约束。我们发现，在单模重力框架内的宇宙学扩散模型可以缓解当前的拉力值。$H_0$。我们还表明，在没有未来奇异之处的情况下，所有扩散模型的非常遥远的未来宇宙学演化都将不断地加速发展。