Jose A. V. Campos

In this work, we investigate the effects of Lorentz symmetry violation on the absorption cross section and quasinormal modes of a rotating acoustic black hole in (2+1) dimensions. The absorption cross section was analyzed analytically, using the low and high frequency regimes, and numerically, through integration of the radial equation. The results showed that Lorentz violation increases the absorption cross section at all energy scales, with a contribution from the rotation parameter B appearing even in the low frequency regime. For the quasinormal modes, we observed that symmetry breaking decreases the real part of the frequencies and increases the magnitude of the corresponding imaginary part, indicating a faster damping of the oscillations.

In the present work, we study a subclass of Horndeski gravity characterized by a non-minimal derivative coupling between a scalar field and the Einstein tensor, as a possible alternative to alleviate the observational tension associated with estimates of the Hubble constant H ₀ . Two scenarios within a flat FRW spacetime were considered. In the first case, the scalar field mimics cold dark matter, whereas in the second case, it acts as dark energy. We derive the dynamical equations and perform a statistical analysis using observational data of H ( z ), obtaining constraints for the cosmological parameters. The results indicate that the model can effectively fit the cosmic expansion rate at late epochs, providing values of H ₀ that are more compatible with local measurements. These results suggest that the non-minimal coupling sector in the Horndeski context constitutes a viable and promising approach to alleviate the H ₀ tension and investigate scenarios beyond the standard cosmological model.