Constraining $f(Q, L_m)$ gravity with bulk viscosity

Y. Myrzakulov; O. Donmez; M. Koussour; S. Muminov; I. Y. Davletov; J. Rayimbaev

doi:10.1016/j.dark.2025.101829

paper

Constraining $f (Q, L_{m})$ gravity with bulk viscosity

arXiv:2407.08837 · doi:10.1016/j.dark.2025.101829

Abstract

We investigate the influence of bulk viscosity on late-time cosmic acceleration within an extended $f (Q, L_{m})$ gravity framework, where the non-metricity $Q$ is non-minimally coupled with the matter Lagrangian $L_{m}$ . Analyzing the function $f (Q, L_{m}) = α Q + β L_{m}$ , we derive exact solutions under non-relativistic matter domination. Using observational datasets ( $H (z)$ , Pantheon supernovae, and their combination), we constrain the model parameters $H_{0}$ , $α$ , $β$ , and $ζ$ . The deceleration parameter transitions from positive to negative values around redshifts $z_{t} \approx 0.80$ to $0.99$ , indicating current accelerated expansion. Moreover, the effective equation of state parameter, $ω_{e f f}$ , resembles quintessence dark energy ( $- 1 < ω_{e f f} < - \frac{1}{3}$ ), with corresponding values from respective datasets. Finally, we use the $O m (z)$ diagnostic, which confirms that our model demonstrates quintessence-like behavior. Our findings underscore the significant role of bulk viscosity in understanding accelerated expansion in the universe within alternative gravity theories.

Minor revision in Physics of the Dark Universe

Constraining $f (Q, L_{m})$ gravity with bulk viscosity

Abstract

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Cited by in corpus (2)

Constraining f(Q,Lm​) gravity with bulk viscosity

Abstract

References in corpus (69)

Cited by in corpus (2)

Constraining $f (Q, L_{m})$ gravity with bulk viscosity