In this work, we test the capability of an exact solution found in the framework of a nonlinear extension of the Israel-Stewart theory to fit the supernovae Ia, gravitational lensing, and black hole shadow data. This exact solution is a generalization of one previously found for a dissipative unified dark matter model in the context of the near-equilibrium description of dissipative processes, where we do not have the full regime of the nonlinear picture. This generalized solution is restricted to the case where a positive entropy production is guaranteed and is tested under the condition that ensures its causality, local existence, and uniqueness. From the observational constraints, we found that this generalized solution is a good candidate in the description of the observational late-time data used in this work, with best-fit values $H_{ 0}=73.2_{ -0.9}^{ +0.8}\,\frac{ km/s}{ Mpc}$, $q_{ 0}=-0.41_{ -0.03}^{ +0.03}$, $\hat{ \xi}_{ 0}=0.88_{ -0.17}^{ +0.09}$, $\epsilon=0.34_{ -0.04}^{ +0.03}$, and $k=0.27_{ -0.20}^{ +0.37}$. Therefore, we show that the nonlinear regime of the Israel-Stewart theory consistently describes the recent accelerated expansion of the universe without the inclusion of some kind of dark energy component and also provides a more realistic description of the fluids that make up the late Universe.
Categories: gr-qc