Constraints on cosmic curvature from cosmic chronometer and quasar observations

Understand

We consider cosmic chronometer (CC) data for the Hubble parameter, quasar (QSO) luminosities data of X-rays and ultraviolet rays emission, and the latest measurements of the present value of the Hubble parameter from 2018 Planck mission (PL18), and SH0ES observations (SHOES) to constrain the present value of cosmic curvature density parameter.

• We consider three kinds of dark energy models: the $\Lambda$CDM model, the wCDM model, and the CPL parametrization.
• In all these three models, we find higher values of the matter-energy density parameter, $\Omega_{\rm m0}$ compared to the one obtained from the Planck 2018 mission of CMB observation.
• Also, we find evidence for a nonflat and closed Universe at 0.5$\sigma$ to 3$\sigma$ confidence levels.