Interacting parametrized post-Friedmann method

TL;DR

This paper applies the interacting parametrized post-Friedmann method to a coupled dark energy model, using extensive cosmological data to constrain the interaction parameter and analyze its effects on cosmic microwave background and matter power spectra.

Contribution

It introduces the application of the IPPF method to a coupled dark energy model and provides observational constraints on the interaction parameter using multiple cosmological probes.

Findings

The coupling parameter is constrained to approximately 0.0014 at 1σ.

The CMB power spectrum shows shifts in peak positions and amplitudes with varying coupling.

Matter power spectrum amplitude is affected at scales larger than 10^{-2} h Mpc^{-1}.

Abstract

We apply the interacting parametrized post-Friedmann (IPPF) method to a coupled dark energy model where the interaction is proportional to dark matter density at background level. In doing so, we perform a Markov Chain Monte-Carlo analysis which combines several cosmological probes including the cosmic microwave background (WMAP9+Planck) data, baryon acoustic oscillation (BAO) measurements, JLA sample of supernovae, Hubble constant (HST), and redshift-space distortion (RSD) measurements through the ${\rm f}\sigma_{8}{\rm (z)}$ data points. The joint observational analysis of ${\rm Planck+WP+JLA+BAO+HST+RSD}$ data leads to a coupling parameter, $\xi_{c}=0.00140_{-0.00080}^{+0.00079}$ at $1\sigma$ level for vanishing momentum transfer potential; this value is reduced a when the momentum transfer potential is switched on, giving $\xi_{c}=0.00136_{-0.00073}^{+0.00080}$ at $1\sigma$ level. The CMB power spectrum shows up a correlation between the coupling parameter $\xi_{c}$ and the position of acoustic peaks or their amplitudes. The first peak's height increases when $\xi_{c}$ takes larger values and its position is shifted. We also obtain the matter power spectrum may be affected by the strength of interaction coupling over scales bigger that $10^{-2} {\rm h~ Mpc^{-1}}$, reducing its amplitude in relation to the vanilla model.