https://doi.org/10.1140/epjc/s10052-025-14432-2
Regular Article - Theoretical Physics
Constraining viscous-fluid models in f(Q) gravity with data
1
Centre for Space Research, North-West University, 2531, Potchefstroom, South Africa
2
Department of Physics, Wolkite University, Wolkite, Ethiopia
3
National Institute for Theoretical and Computational Sciences (NITheCS), 2520, Potchefstroom, South Africa
4
Cosmology and Gravity Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, 7700, Cape Town, South Africa
5
Departamento de Física Fundamental, Universidad de Salamanca, 37008, Salamanca, Spain
Received:
9
October
2024
Accepted:
15
June
2025
Published online:
7
July
2025
We investigate the impact of bulk viscosity on the accelerating expansion and large-scale structure formation of a Universe in which the underlying gravitational interaction is described by f(Q) gravity. Various paradigmatic choices of the f(Q) gravity theory, including power-law, exponential, and logarithmic models, are considered. To test the cosmological viability of these f(Q) gravity models, we use the Baryon Acoustic Oscillations (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) Survey, cosmic chronometers (CC) from Hubble measurements, the SNIa distance moduli measurements from the PantheonP + SH0ES, growth rate (f-data), and redshift-space distortions 
datasets, the latter two once the linear cosmological perturbations, growth rate f(z), and redshift-space distortion 
are studied. Thus, we perform the combined analyses for: PantheonP + SH0ES, PantheonP + SH0ES + f, and PantheonP + SH0ES + 
. We compute the best-fit values 
n, p and 
including the bulk viscosity coefficient 
Through a detailed statistical analysis, based on the Akaike Information Criterion (AIC) and Bayesian/Schwartz Information Criterion (BIC), a statistical comparison of the f(Q) gravity models with 
CDM is made. Among the three f(Q) models, only the non-viscous f(Q) power-law model yields robust parameter estimates and substantial observational support without any outright rejections. In contrast, both exponential and logarithmic f(Q) models (with or without bulk viscosity) are rejected by multiple model selection criteria. Moreover, adding bulk viscosity consistently increases 
AIC and BIC values, indicating that its inclusion is not statistically justified.
© The Author(s) 2025
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