English

Cosmological models based on a complex scalar field with a power-law potential associated with a polytropic equation of state

General Relativity and Quantum Cosmology 2022-08-17 v1

Abstract

We construct cosmological models based on a complex scalar field with a power-law potential V=Kγ1(m)2γφ2γV=\frac{K}{\gamma-1}(\frac{m}{\hbar})^{2\gamma}|\varphi|^{2\gamma} associated with a polytropic equation of state P=KργP=K\rho^{\gamma} (the potential associated with an isothermal equation of state P=ρkBT/mP=\rho k_B T/m is V=mkBT2φ2[ln(m2φ2/ρ2)1]V=\frac{m k_B T}{\hbar^2}|\varphi|^2 [\ln(m^2|\varphi|^2/\rho_*\hbar^2)-1] and the potential associated with a logotropic equation of state P=Aln(ρ/ρP)P=A\ln(\rho/\rho_P) is V=A[ln(m2φ2/2ρP)+1]V=-A[\ln(m^2|\varphi|^2/\hbar^2\rho_P)+1]). We consider a fast oscillation regime of ``spintessence'' where the equations of the problem can be simplified. We study all possible cases with arbitrary (positive and negative) values of the polytropic constant and polytropic index. The Λ\LambdaCDM model, the Chaplygin gas model and the Bose-Einstein condensate model are recovered as particular cases of our study corresponding to a constant potential (γ=0\gamma=0), an inverse square-law potential (γ=1\gamma=-1), and a quartic potential (γ=2\gamma=2). We also derive the two-fluid representation of the Chaplygin gas model.

Keywords

Cite

@article{arxiv.2111.01828,
  title  = {Cosmological models based on a complex scalar field with a power-law potential associated with a polytropic equation of state},
  author = {Pierre-Henri Chavanis},
  journal= {arXiv preprint arXiv:2111.01828},
  year   = {2022}
}