Forecasts for interacting dark energy with time-dependent momentum exchange
Nathan Cruickshank, Robert Crittenden, K. Koyama, Marco Bruni
Abstract
Abstract Models of interacting dark energy and dark matter offer a possible solution to cosmological tensions. In this work, we examine a pure momentum-exchange model with a time-dependent coupling strength ξ ( z ) that could help to alleviate the S 8 tension. We perform Fisher forecasting and MCMC analysis to constrain the coupling strength of this interaction for different redshift bins 0.0 < z < 2.1, using the specifications of upcoming DESI-like surveys. For this analysis, we examine both a model with a constant equation of state w = -0.9, as well as a thawing dark energy model with an evolving w ( z ). We show that, for a constant equation of state, ξ ( z ) can be well constrained in all redshift bins. However, due to a weaker effect at early times, the constraints are significantly reduced at high redshifts in the case of a thawing w ( z ) model.