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arXiv · 2510.12472

Observational Constraints on Chaplygin Gas Models in Non-Minimally Coupled Power Law $f(Q)$ Gravity with Quasars

Nakul Aggarwal·Ali Pourmand·Fatimah Shojai·Harish Parthasarathy
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Abstract

In the framework of $f(Q)$ gravity, where gravity emerges from non-metricity $Q$, we explore the cosmological implications of its non-minimal coupling to matter. Inspired by the recent success of Chaplygin gas models in explaining dark energy, we consider a background fluid composed of baryonic matter, radiation, and a family of Chaplygin gas variants namely Generalized Chaplygin Gas (GCG), Modified Chaplygin Gas (MCG), and Variable Chaplygin Gas (VCG). We constrain these models with three recent observational datasets: Observational Hubble Data (OHD), Baryonic Acoustic Oscillation (BAO) measurements, and Quasi-Stellar Objects (QSO) data. For the QSO dataset, we propose an analytical expression for errors in comoving distance to circumvent the reliance on Monte Carlo simulations. Using kinematic diagnostics such as the deceleration and jerk parameters and Om diagnostic, we assess deviations of the proposed models from $\Lambda$CDM. Our joint analysis of the three datasets reveals that the transition redshift from a decelerated to an accelerated expansion of the universe for the GCG, MCG and VCG models is $0.620^{+0.018}_{-0.017}$, $0.537^{+0.017}_{-0.017}$ and $0.470^{+0.012}_{-0.012}$ respectively, indicating a departure from $\Lambda$CDM.

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Nakul Aggarwal, Ali Pourmand, Fatimah Shojai, Harish Parthasarathy. 2025-10-14. Observational Constraints on Chaplygin Gas Models in Non-Minimally Coupled Power Law $f(Q)$ Gravity with Quasars. https://doi.org/10.1016/j.aop.2025.170266

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