2018/06/30 by Hassan Firouzjahi, Mohammad Ali Gorji, Seyed Ali Hosseini Mansoori +2 · 1 citation
Physics and Astronomy · #Adiabatic process #Black Holes and Theoretical Physics #Conformal map #Cosmological perturbation theory #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Entropy (arrow of time) #Perturbation (astronomy) #Scalar (mathematics) #Transformation (genetics) #astro-ph.CO #gr-qc #hep-th
paper · pdf · doi:10.1088/1475-7516/2018/11/046
21 pages, accepted for publication in JCAP
openalex created_date 2018/07/10 · arxiv created 2018/11/17 · openalex publication_date 2018/11/29 · arxiv updated 2018/12/05 · openalex updated_date 2026/08/05
We extend the disformal transformation to models with two scalar fields and look at its singular limit. Solving the eigentensor equation for the Jacobian of the transformation of the metrics we find the two-field extension of the mimetic scenario in the singular conformal limit. At the background level the setup mimics the roles of dark matter cosmology. We decompose the perturbations into the adiabatic and entropy modes in which the adiabatic perturbation is tangential to the classical trajectory while the entropy mode is perpendicular to it. We show that the adiabatic mode is frozen while the entropy mode propagates with the sound speed equal to unity with no instabilities.