We analyse some open debates in cosmology in the light of the most updated quasar (QSO) sample, covering a wide redshift range up to z ∼ 7.5, combined with type Ia supernovae (SNe) and baryon acoustic oscillations (BAO) data. Indeed, extending the cosmological analyses with high-redshift data, such as QSOs, is the key to distinguishing between different cosmological models that are instead degenerate at low redshifts, and allowing a better constraint on a possible dark energy (DE) evolution. Also, we discuss different combinations of the BAO, SNe, and QSO data to understand their compatibility and their implications for the non-flat Universe and extensions of the standard cosmological model. Specifically, we consider a flat and non-flat ΛCDM cosmology, a flat and non-flat DE model with a constant DE equation of state parameter (w), and four flat DE models with variable w, namely the Chevallier-Polarski-Linder and Jassal-Bagla-Padmanabhan models, and an "exponential" and "rational" parameterisations. We find that a joint analysis of QSO+SNe with BAO is only possible in the context of a flat Universe. Indeed BAO confirms the flatness condition assuming a curved geometry, whilst SNe+QSO show evidence of a closed space. We also find that the matter component, Ω M,0 , is fully consistent with Ω M,0 = 0.3 in all the data sets assuming a flat ΛCDM model. Yet, all the other analysed models show a statistically significant deviation at > 3σ from this prediction by making use of the SNe+QSO sample, which remains still significant (2-3σ) with the combined SNe+QSO+BAO data set. In the models where the DE density evolves with time, the SNe+QSO+BAO data always prefer Ω M,0 > 0.3, w 0 < −1 and w a greater, but statistically consistent, than w a = 0. This DE phantom behaviour is mainly driven by the contribution of SNe+QSO, while BAO are closer to the prediction of the flat ΛCDM model (also due to their large uncertainties).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.