On the Interacting Dark Energy Scenarios—The Case for Hubble Constant Tension

The Hubble constant \(H_0\) is one of the important cosmological parameters measuring the expansion rate of our universe at present moment. Over the last couple of years, \(H_0\) has created an enormous amount of debates interests in the astrophysical and cosmological communities for its different estimations at many standard deviations by different observational surveys. The recent estimation of \(H_0\) from the cosmic microwave background observations by Planck within the \(\varLambda \) -Cold Dark Matter ( \(\varLambda \) CDM) paradigm is in tension with \(\gtrsim 5 \sigma \) confidence with S \(H_0\) ES (Supernovae and \(H_0\) for the Equation of State of dark energy) collaboration. As a result, revision of the standard \(\varLambda \) CDM model has been suggested in various ways in order to examine whether such scenarios can solve this \(H_0\) tension. Among the list of the proposed cosmological scenarios, in this chapter we focus on a generalized cosmological theory in which the dark components of the universe, namely, Dark Matter (DM) and Dark Energy (DE) are allowed to interact with each other in a non-gravitational way, widely known as the Interacting DE or Coupled DE scenarios. These interacting scenarios have received magnificent attention in the scientific community for their appealing consequences. Specifically, in the context of \(H_0\) tension, it has been observed that the interacting DE scenarios can lead to higher values of the Hubble constant ( \(H_0\) ) value, and consequently, the tension on \(H_0\) can be either alleviated or solved. In this chapter we review various interacting DE scenarios and their roles in alleviating the \(H_0\) tension.