Constraints for the thawing and freezing potentials. (16th January 2018)

• Record Type: Journal Article
• Authors: Hara, Tetsuya; Suzuki, Anna; Saka, Shogo; Tanigawa, Takuma
• Is Part Of: Progress of theoretical and experimental physics. Volume 2018:Number 1(2018)
• Publication Date: 2018-01-16
• Subjects: E64 -- E80; Physics -- Periodicals; Mathematical physics -- Periodicals; 530.05
• DOI: 10.1093/ptep/ptx160
• Languages: English
• ISSNs: 2050-3911

Abstract

Abstract: We study the accelerating present universe in terms of the time evolution of the equation of state $w(z)$ (redshift $z$ ) due to thawing and freezing scalar potentials in the quintessence model. The values of $dw/da$ and $d^2w/da^2$ at a scale factor of $a = 1$ are associated with two parameters of each potential. For five types of scalar potentials, the scalar fields $Q$ and $w$ as functions of time $t$ and/or $z$ are numerically calculated under the fixed boundary condition of $w(z=0)=-1+\Delta$ . The observational constraint $w_{\rm obs}$ (Planck Collaboration, arXiv:1502.01590) is imposed to test whether the numerical $w(z)$ is in $w_{\rm obs}$ . Some solutions show thawing features in the freezing potentials. Mutually exclusive allowed regions in the $dw/da$ vs. $d^2w/da^2$ diagram are obtained in order to identify the likely scalar potential and even the potential parameters for future observational tests.