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arxiv 2103.07139 v1 pith:EERFGPSA submitted 2021-03-12 astro-ph.CO

Multiple measurements of quasars acting as standard probes: model independent calibration and exploring the Dark Energy Equation of States

classification astro-ph.CO
keywords quasarsmeasurementsequationprobescriterionmodelsstandardstate
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Recently, two classes of quasar samples were identified, which are promising as new cosmological probes extending to higher redshifts. The first sample uses the nonlinear relation between the ultraviolet and X-ray luminosities of quasars to derive luminosity distances, whereas the linear sizes of compact radio quasars in the second sample can serve as standardized rulers, providing angular-diameter distances. In this study, under the assumption of a flat universe, we refreshed the calibration of multiple measurements of high-redshift quasars (in the framework of a cosmological-model-independent method with the newest Hubble parameters data). Furthermore, we placed constraints on four models that characterize the cosmic equation of state ($w$). The obtained results show that: 1) the two quasar samples could provide promising complementary probes at much higher redshifts, whereas compact radio quasars perform better than ultraviolet and X-ray quasars at the current observational level; 2) strong degeneracy between the cosmic equation of state ($w$) and Hubble constant ($H_0$) is revealed, which highlights the importance of independent determination of $H_0$ from time-delay measurements of strongly lensed Quasars; 3)together with other standard ruler probes, such as baryon acoustic oscillation distance measurements, the combined QSO+BAO measurements are consistent with the standard $\Lambda$CDM model at a constant equation of state $w=-1$; 4) ranking the cosmological models, the polynomial parametrization gives a rather good fit among the four cosmic-equation-of-state models, whereas the Jassal-Bagla-Padmanabhan (JBP) parametrization is substantially penalized by the Akaike Information Criterion and Bayesian Information Criterion criterion.

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