A new test of dynamical dark energy models and cosmic tensions in Hořava gravity

Abstract

ABSTRACT Hořava gravity has been proposed as a renormalizable, higher derivative, Lorentz-violating quantum gravity model without ghost problems. A Hořava gravity-based dark energy (HDE) model for dynamical dark energy has also been proposed earlier by identifying all the extra (gravitational) contributions from the Lorentz-violating terms as an effective energy–momentum tensor in Einstein equation. We consider a complete cosmic microwave background, baryon acoustic oscillation (BAO), and supernova Ia data test of the HDE model by considering general perturbations over the background perfect HDE fluid. Except from BAO, we obtain the preference of non-flat universes for all other data set combinations. We obtain a positive result on the cosmic tensions between the Hubble constant H0 and the cosmic shear S8, because we have a shift of H0 towards a higher value, though not enough for resolving the H0 tension, but the value of S8 is unaltered. This is in contrast to a rather decreasing H0 but increasing S8 in a non-flat Lambda cold dark matter (LCDM). For all other parameters, like Ωm and $\Omega _\Lambda$, we obtain quite comparable results with those of LCDM for all data sets, especially with BAO, so that our results are close to a cosmic concordance between the data sets, contrary to the standard non-flat LCDM. We also obtain some undesirable features, like an almost null result on Ωk, which gives back the flat LCDM, if we do not predetermine the sign of Ωk, but we propose several promising ways for improvements by generalizing our analysis.