Redshift evolution of the X-ray and UV luminosity relation of quasars: calibrated results from SNe Ia

Abstract

Quasars could serve as standard candles if the relation between their ultraviolet and X-ray luminosities can be accurately calibrated. Previously, we developed a model-independent method to calibrate quasar standard candles using the distances-redshift relation reconstructed from Type Ia supernova at z<2 using Gaussian process regression. Interestingly, we found that the calibrated quasar standard candle dataset preferred a deviation from $\Lambda$CDM at redshifts above z>2. One interpretation of these findings is that the calibration parameters of the quasar UV-X-ray luminosity relationship evolves with redshift. In order to test the redshift dependence of the quasar calibration in a model-independent manner, we divided the quasar sample whose redshift overlap with the redshift coverage of Pantheon+ Type Ia supernova compilation into two sub-samples: a low-redshift quasar sub-sample and a high-redshift quasar sub-sample. Our present results show that there is about a 4$\sigma$ inconsistency between the quasar parameters inferred from the high-redshift quasar sub-sample and from the low-redshift sub-sample if no evolution of the quasar relation is considered. This inconsistency suggests the necessity of considering redshift evolution for the relationship between the quasars${}^{\prime }$ ultraviolet and X-ray luminosities. We then test an explicit parametrization of the redshift evolution of the quasar calibration parameters via $\gamma (z)={\gamma }_0+{\gamma }_1(1+z)$ and $\beta (z)={\beta }_0+{\beta }_1(1+z)$. Combining this redshift-dependent calibration relationship with the distance-redshift relationship reconstructed from Pantheon+ supernova compilation, we find the high-redshift sub-sample and low-redshift sub-sample become consistent at the 1$\sigma$ level, which means that the parameterized form of $\gamma (z)$ and $\beta (z)$ works well at describing the evolution of the quasar calibration parameters.

12 pages, 7 figures

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Cited by in corpus (3)

• Probing the Cosmic Distance Duality Relation via Non-Parametric Reconstruction for High Redshifts
• Breaking the Mass-sheet Degeneracy in Time-delay Cosmology with Lensed and Unlensed Type Ia Supernovae
• Redshift Evolution of the HII Galaxy $L$-$\sigma$ Relation: Gaussian Process Analysis and Cosmological Implications