Apparent acceleration due to relativistic cosmological models more complex than FLRW as a possible alternative to dark energy

The Szekeres inhomogeneous models are used in order to fit supernovacombined data sets. We show that with a choice of the spatial curvature function that is guided by current observations, the models fit the supernovadata almost as well as the LCDM model without requiring a dark energy component. The Szekeres models were originally derived as an exact solution to Einstein’s equations with a general metricthat has no symmetries and are regarded as good candidates to model the true lumpy universe that we observe. The null geodesics in these models are not radial and require numerical integration. The best fit modelfound is also consistent with the requirement of spatial flatness at the CMB scale. Interestingly, apparent acceleration due to inhomogeneities is also linked to the profound problem of averaging in cosmology. The first results presented here seem to encourage further investigations of apparent acceleration using various inhomogeneous models using full CMB spectra as well as large structure.