# On sign-changeable interaction in FLRW cosmology

## TL;DR

This paper explores a sign-changeable interaction model in FLRW cosmology, analyzing its effects on dark energy dynamics and constraining parameters with recent observational data.

## Contribution

It introduces a nonlinear sign-changeable interaction in dark sector models and constrains it using Bayesian analysis with supernova and Hubble data.

## Key findings

- Effective dark sector equations include Chaplygin gas types.
- Constraints suggest compatibility with late-time universe observations.
- Model provides new insights into dark energy interactions.

## Abstract

We investigate an interacting two-fluid model in a spatially flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) Universe, when the energy transfer between these two dark components is produced by a factorisable nonlinear sign-changeable interaction depending linearly on the energy density and quadratically on the deceleration parameter. We solve the source equation and obtain the effective energy densities of the dark sector and their components. We show that the effective equation of state of the dark sector includes some of the several kind of Chaplygin gas equations of state as well as a generalization of the polytropic equation of state. We use bayesian statistics methods to constrain free parameters in the models during its most recent evolution considering supernovae type Ia and measurements of the Hubble expansion rate. The resulting constraints provide new information on sign-changeable interactions, its equivalences and compatibility with previous models and novel late time universe dynamics.