Screening Lambda in a new modified gravity model
Por:
Akarsu, Ozgur, Barrow, John D., Board, Charles V. R., Uzun, N. Merve, Vazquez, J. Alberto
Publicada:
1 oct 2019
Resumen:
We study a new model of Energy-Momentum Squared Gravity (EMSG), called
Energy-Momentum Log Gravity (EMLG), constructed by the addition of the
term f(T mu nu T mu nu)=alpha ln(lambda T mu nu T mu
nu)textbackslashd, envisaged as a correction, to the Einstein-Hilbert
action with cosmological constant Lambda. The choice of this
modification is made as a specific way of including new terms in the
right-hand side of the Einstein field equations, resulting in constant
effective inertial mass density and, importantly, leading to an explicit
exact solution of the matter energy density in terms of redshift. We
look for viable cosmologies, in particular, an extension of the standard
Lambda CDM model. EMLG provides an effective dynamical dark energy
passing below zero at large redshifts, accommodating a mechanism for
screening Lambda in this region, in line with suggestions for
alleviating some of the tensions that arise between observational data
sets within the standard Lambda CDM model. We present a detailed
theoretical investigation of the model and then constrain the free
parameter alpha `, a normalisation of alpha, using the latest
observational data. The data does not rule out the Lambda CDM limit of
our model (alpha `=0), but prefers slightly negative values of the EMLG
model parameter (alpha `=-0.032 +/- 0.043), which leads to the screening
of Lambda. We also discuss how EMLG relaxes the persistent tension that
appears in the measurements of H0 within the standard Lambda CDM model.
Filiaciones:
Akarsu, Ozgur:
Istanbul Tech Univ, Dept Phys, TR-34469 Istanbul, Turkey
Barrow, John D.:
Univ Cambridge, Ctr Math Sci, DAMTP, Wilberforce Rd, Cambridge CB3 0WA, England
Board, Charles V. R.:
Univ Cambridge, Ctr Math Sci, DAMTP, Wilberforce Rd, Cambridge CB3 0WA, England
Uzun, N. Merve:
Bogazici Univ, Dept Phys, TR-34342 Istanbul, Turkey
Vazquez, J. Alberto:
Univ Nacl Autonoma Mexico, Inst Ciencias Fis, Apdo Postal 48-3, Cuernavaca 62251, Morelos, Mexico
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