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Abstract We consider a k-essence scalar field model for the late-time cosmic acceleration in which the sound speed, parametrized as cₛ c s is constant. We compute the relevant background and perturbation quantities corresponding to the observables like cosmic microwave background, type Ia supernova, cosmic chronometers, baryon acoustic oscillations, and the f ₈ f σ 8. We put constraints on the cₛ² c s 2 parameter from these observations along with other parameters. We find lower values of cₛ² c s 2 which are close to zero are tightly constrained. Particularly, we find mean value of ₁0 (cₛ²) log 10 (c s 2) to be -0. 61 - 0. 61 and cₛ² 10^-3 c s 2 ≤ 10 - 3 is more than 3 σ away from this mean value. This means these observations favor a homogeneous dark energy component compared to the clustering one.
Dinda et al. (Wed,) studied this question.