Type V singularities in non-standard cosmological backgrounds

Interest in cosmological singularities has remarkably grown in recent times, particularly on future singularities with the discovery of late-time acceleration of the universe and dark energy. While there has been an expansive literature which has discussed the occurrence of Type I-IV singularities in many non-standard cosmologies, w/Type V singularities have not yet been explored in exotic cosmological settings. So in this work we pursue the same and discuss the occurrence of w-singularities in a variety of non-standard cosmologies. We consider the RS-II Braneworld cosmology, an F(R) gravity cosmology which gives viable late time acceleration and we also consider cosmologies due to modified area-entropy relations, generalized uncertainty principles, holographic renormalization and Chern-Simons gravity (all of which can be coincidentally described by the same form of the modified Friedmann equation). We show that w-singularities will occur in exactly the same conditions in all these cosmological settings as they do in the usual general relativistic cosmology if one considers a power series expansion ansatz for the scale factor. We also show that if one considers an exponential form of the scale factor then while Type V singularities in the RS-II Braneworld and Chern-Simons cosmologies occur in the same conditions as in the standard general relativistic case, there is a significant difference in the conditions when one considers the f(R) gravity case. These results are surprising overall, as one would usually not expect cosmological singularities to occur in almost the same conditions in non-standard cosmologies as they do in the usual standard cosmology. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

Interest in cosmological singularities, particularly future singularities, has grown recently with the discovery of late-time acceleration and dark energy. This study explores the occurrence of w-singularities in various non-standard cosmologies and finds that they occur under the same conditions as in the usual general relativistic cosmology. These unexpected results highlight the similarities between non-standard and standard cosmologies in terms of the conditions for cosmological singularities.