Exact solutions of the cosmological perturbations in a pressureless medium
Jai-chan Hwang
Abstract
Jai-chan Hwang
Abstract
We present integral-form exact solutions of the cosmological perturbations in a pressureless medium. The solutions include the background three-space curvature and the cosmological constant and are valid outside the Jeans scale, which is negligible compared to the horizon scale in a matter-dominated medium. Solutions are presented for recently introduced six different gauge choices, and we discuss the relations to Newtonian analysis. We identify the perturbed density variable in the comoving gauge, the perturbed velocity, and potential variables in the zero-shear gauge as having correct Newtonian correspondences. On subhorizon scales, behavior of the fluid and potential variables in the uniform-expansion gauge also show a correct match with the Newtonian results.
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We present integral-form exact solutions of the cosmological perturbations in a pressureless medium. The solutions include the background three-space curvature and the cosmological constant and are valid outside the Jeans scale, which is negligible compared to the horizon scale in a matter-dominated medium. Solutions are presented for recently introduced six different gauge choices, and we discuss the relations to Newtonian analysis. We identify the perturbed density variable in the comoving gauge, the perturbed velocity, and potential variables in the zero-shear gauge as having correct Newtonian correspondences. On subhorizon scales, behavior of the fluid and potential variables in the uniform-expansion gauge also show a correct match with the Newtonian results.
Key concepts: Physics, Cosmology, Cosmological constant, Theoretical physics, Universe, Metric expansion of space, Mathematical physics, Classical mechanics