论文标题

对称触发性重力中的粘性流体宇宙学

Viscous fluid cosmology in symmetric teleparallel gravity

论文作者

Solanki, Raja, Rana, Dheeraj Singh, Mandal, Sanjay, Sahoo, P. K.

论文摘要

在此手稿中,我们通过假设三种不同形式的散装粘度系数,特别是$(i)ζ=ζ_{0}+ζ_{1}+ζ_{1} {1} \ left(\ frac {\ frac {\ dot {a} a} a} a} a} +ζ_{2} \ left(\ frac {\ ddot {a}}} {\ dot {a}}} \ right)$,$(ii)ζ=ζ_{0} +ζ_{1} {1} \ left(\ frac {\ frac {\ dot {\ dot { $(iii)ζ=ζ_{0} $和线性$ f(q)$模型,尤其是$ f(q)=αq$其中$α\ neq 0 $是免费的模型参数。我们使用组合的H(Z)+万神殿+BAO数据集估算了大量粘度系数和模型参数值。我们通过使用相空间方法研究了宇宙学大量粘性模型的渐近行为。我们发现,与所有三种情况相对应,我们的模型描述了宇宙从物质中的演变,主导了减速时期(过去的吸引子)到稳定的Deitter加速时期(未来的吸引子)。此外,我们研究有效压力的身体行为,有效状态方程(EOS)和状态基础参数。我们发现,存在大量粘度的压力成分显示出负面的行为,有效的EOS参数预测了所有三种情况的宇宙的加速膨胀阶段。此外,我们获得了模型的轨迹位于典型区域,并且在远后的$λ$ CDM固定点会收敛。我们发现,加速的值得阶段纯粹来自$ \barζ_0$ case,而没有对GR进行任何几何修改。此外,我们发现所有三种粘度系数的延迟行为都是相同的。

In this manuscript, we analyze the viscous fluid cosmological model in the framework of recently proposed $f(Q)$ gravity by assuming three different forms of bulk viscosity coefficients, specifically, $(i)ζ=ζ_{0}+ζ_{1}\left( \frac{\dot{a}}{a}\right) +ζ_{2}\left( \frac{\ddot{a}}{\dot{a}}\right) $, $(ii)ζ=ζ_{0}+ζ_{1}\left( \frac{\dot{a}}{a}\right)$, and $(iii)ζ=ζ_{0}$ and a linear $f(Q)$ model, particularly, $f(Q)=αQ$ where $α\neq 0$ is free model parameter. We estimate the bulk viscosity coefficients and the model parameter values using the combined H(z)+Pantheon+BAO data set. We study the asymptotic behavior of our cosmological bulk viscous model by utilizing the phase space method. We find that corresponding to all three cases, our model depicts the evolution of the universe from matter dominated decelerated epoch (a past attractor) to a stable de-sitter accelerated epoch (a future attractor). Further, we study the physical behavior of effective pressure, effective equation of state (EoS), and the statefinder parameters. We find that the pressure component in the presence of bulk viscosity shows negative behavior and the effective EoS parameter predicts the accelerated expansion phase of the universe for all three cases. Moreover, we obtain that the trajectories of our model lie in the quintessence region and it converges to the $Λ$CDM fixed point in the far future. We find that the accelerated deSitter like phase comes purely from the $\barζ_0$ case without any geometrical modification to GR. Moreover, we find that the late-time behavior of all three cases of viscosity coefficients are identical.

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