Emergence of a cosmological constant in anisotropic fluid cosmology

We investigate anisotropic fluid cosmology in a situation where the spacetime metric back-reacts local, time-dependent way to presence of inhomogeneities. derive exact solutions Einstein field equations describing Friedmann-Lemaitre-Robertson-Walker (FLRW) large scale cosmological evolution local inhomogeneities and back reaction. use our derivation tackle constant problem. A emerges by averaging reaction term on spatial scales order $100 \ \text{Mpc}$, at which universe begins appear homogeneous isotropic. find that magnitude "emerged" agrees with astrophysical observations is related natural baryonic matter density. Thus, there no coincidence problem framework.