Energy conditions in <i>f</i> ( <i>Q</i> , <i>T</i> ) gravity

Abstract The recently proposed f ( Q , T ) gravity (Xu et al 2019 Eur. Phys. J. C 79 , 708) is an extension of the symmetric teleparallel gravity. The gravitational action L is given by an arbitrary function f of the non-metricity Q and the trace of the matter-energy momentum tensor T . In this paper, we examined the essence of some well prompted forms of f ( Q , T ) gravity models i.e. f ( Q , T ) = mQ + bT and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>f</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>Q</mml:mi> <mml:mo>,</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="italic">mQ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>n</mml:mi> <mml:mo>+</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mo>+</mml:mo> <mml:mi mathvariant="italic">bT</mml:mi> </mml:math> where m , b , and n are model parameters. We have used the proposed deceleration parameter, which predicts both decelerated and accelerated phases of the Universe, with the transition redshift by recent observations and obtains energy density ( ρ ) and pressure ( p ) to study the various energy conditions for cosmological models. The equation of state parameter ( ω ≃ −1) in the present model also supports the accelerating behavior of the Universe. In both, the models, the null, weak, and dominant energy conditions are obeyed with violating strong energy conditions as per the present accelerated expansion.

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