Probing modified gravity theories with multiple measurements of high-redshift quasars

TL;DR

This study assesses how multiple high-redshift quasar measurements can constrain various modified gravity theories, revealing that current data still allow for the possibility that the standard Lambda-CDM model may not be optimal.

Contribution

It evaluates the constraining power of quasar data on several modified gravity models and combines these with BAO data for improved cosmological constraints.

Findings

Quasar data alone do not definitively favor Lambda-CDM over modified gravity models.

Combining quasar and BAO data enhances the ability to discriminate between cosmological models.

Current observations still permit the possibility that modified gravity theories could explain cosmic acceleration.

Abstract

In this paper, we quantify the ability of multiple measurements of high-redshift quasars (QSOs) to constrain several theories of modified gravity, including the Dvali-Gabadadze-Porrati braneworld scenario, generalized Chaplygin gas, $f(T)$ modified gravity, and Modified Polytropic Cardassian model. Recently released sample of 1598 quasars with X-ray and UV flux measurements in the redshift range of $0.036\leq z \leq 5.1003$, as well as a compilation of 120 intermediate-luminosity radio quasars covering the redshift of $0.46 < z < 2.76$ are respectively used as standard probes at higher redshifts. For all considered modified gravity theories, our results show that there is still some possibility that the standard $\Lambda$CDM scenario might not be the best cosmological model preferred by the current quasar observations. In order to improve cosmological constraints, the quasar data are also combined with the latest observations of baryon acoustic oscillations (BAO), which strongly complement the constraints. Finally, we discuss the support given by the data to modified gravity theories, applying different information theoretic techniques like the Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC) and Jensen-Shannon divergence (JSD).