Current observations indicate that, on a large enough scale, the universe is homogeneous and isotropic. However, this does not preclude the possibility of some anisotropy having occurred during the early stages of the evolution of the universe, which could then have been damped out later. This idea has aroused interest in the Bianchi models, which are homogeneous but anisotropic. Secondly, there is much interest in modified gravity these days due to the problems that the usual ΛCDM model faces in general relativity. Hence, in this paper, a study was conducted on the Bianchi type-I cosmological model in f(R,T)-modified gravity. Following some ideas from cosmography, a specific form of the deceleration parameter was assumed, leading to a model that exhibited a transition from early deceleration to late-time acceleration. The derived model approached isotropy at late times. The physical properties of the model were discussed, and expressions for the various parameters of the model were derived. It is also possible to make progress towards solving the cosmological constant problem, since in this model in f(R,T) gravity, a variable cosmological-type parameter arose, which was large early on but decreased to a constant value in later times.

中文翻译：

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修正引力理论中的各向异性宇宙学模型

目前的观察表明，在足够大的尺度上，宇宙是均匀和各向同性的。然而，这并不排除在宇宙演化的早期阶段发生了一些各向异性的可能性，这些各向异性可能会在以后被抑制。这个想法引起了对同质但各向异性的 Bianchi 模型的兴趣。其次，由于通常的 ΛCDM 模型在广义相对论中面临的问题，现在人们对修正引力很感兴趣。因此，本文对f ( R,T)-修正重力。根据宇宙学的一些想法，假设了一种特定形式的减速参数，从而产生了一个模型，该模型展示了从早期减速到后期加速的过渡。派生模型在后期接近各向同性。讨论了模型的物理特性，推导出了模型各参数的表达式。也有可能在解决宇宙常数问题方面取得进展，因为在f ( R,T ) 引力模型中，出现了一个可变的宇宙类型参数，该参数在早期很大，但在以后降低到恒定值。