Constraints on dark energy from the gravitational wave background

Jafar Khodagholizadeh

doi:10.1140/epjc/s10052-023-12183-6

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 988
https://doi.org/10.1140/epjc/s10052-023-12183-6

Regular Article - Theoretical Physics

Constraints on dark energy from the gravitational wave background

Jafar Khodagholizadeh^a

Department of Physics Education, Farhangian University, P.O. Box 14665-889, Tehran, Iran

^a gholizadeh@ipm.ir

Received: 27 July 2023
Accepted: 23 October 2023
Published online: 1 November 2023

Abstract

Current observational data indicate that dark energy (DE) is a cosmological constant without considering its conclusiveness evidence. Considering the dynamic nature of $Λ$ $\Lambda$ individually as a function of time and the scale factor, we review their effects on the gravitational waves. This article is a continuation of the previous work (Khodagholizadeh in JHEAp 36:48–54, 2022), in which DE only was based on Hubble’s parameter and/or its derivatives. For the DE model based on the scale factor ( $a^{- m}$ $a^{-m}$ ), the results showed that the parameter m is more limited as $2 < m ⩽ 3$ $2 < m \leqslant 3$ compared with the other models and due to the small value of DE density at the early universe. It is only in the mode $m = 3$ $$m=3$$ that DE affects the low-frequency gravitational waves when its frequency is less than the $10^{- 3}$ $10^{-3}$ Hz in a matter-dominated epoch. The broad bound on reducing the amplitude and the B-B polarization multipole coefficients, from maximum to minimum, is for the models developed based on the Hubble parameter function. There are primary sources of low- and very low-frequency GWs, such as the coalescence of massive black hole binaries with $M_{bh} > 10^{3} M_{sun}$ $M_{bh} > 10^{3} M_{sun}$ , to determine the type of DE by mHz frequency space experiments (e.g., LISA) and by nHz-range NANOGrav 15-year data.

© The Author(s) 2023

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