Cosmological signatures of torsion and how to distinguish torsion from the dark sector
Abstract
Torsion is a nonRiemannian geometrical extension of general relativity that allows including the spin of matter and the twisting of spacetime. Cosmological models with torsion have been considered in the literature to solve problems of either the very early (high redshift z ) or the presentday Universe. This paper focuses on distinguishable observational signatures of torsion that could not be otherwise explained with a scalar field in pseudoRiemannian geometry. We show that when torsion is present, the cosmic duality relation between the angular diameter distance, D_{A}, and the luminosity distance, D_{L}, is broken. We show how the deviation described by the parameter η =D_{L}/[D_{A}(1 +z )^{2}]1 is linked to torsion and how different forms of torsion lead to specialcase parametrizations of η , including η_{0}z , η_{0}z /(1 +z ), and η_{0}ln (1 +z ). We also show that the effects of torsion could be visible in lowredshift data, inducing biases in supernovaebased H_{0} measurements. We also show that torsion can impact the ClarksonBassettLu (CBL) function C (z )=1 +H^{2}(D D^{''}D^{'2})+H H^{'}D D^{'}, where D is the transverse comoving distance. If D is inferred from the luminosity distance, then, in general, nonzero torsion models, C (z )≠0 . For pseudoRiemannian geometry, the FriedmannLemaîtreRobertsonWalker metric has C (z )≡0 ; thus, the measurement of the ClarksonBassettLu function could provide another diagnostic of torsion.
 Publication:

Physical Review D
 Pub Date:
 May 2020
 DOI:
 10.1103/PhysRevD.101.104046
 arXiv:
 arXiv:2003.06528
 Bibcode:
 2020PhRvD.101j4046B
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 12 pages, 6 figures, 1 table