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arXiv · 2309.10538

Constraints on the speed of sound in the k-essence model of dark energy

Bikash R. Dinda·Narayan Banerjee
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Abstract

We consider a particular k-essence scalar field model for the late-time cosmic acceleration in which the sound speed, parametrized as $c_s$ 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 $f\sigma_8$. We put constraints on the $c_s^2$ parameter from these observations along with other parameters. We find lower values of $c_s^2$ which are close to zero are tightly constrained. Particularly, we find mean value of $\log_{\rm 10} (c_s^2)$ to be $-0.61$ and $c_s^2 \leq 10^{-3}$ is more than 3$\sigma$ away from this mean value. This means these observations favor a homogeneous dark energy component compared to the clustering one.

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Bikash R. Dinda, Narayan Banerjee. 2023-09-19. Constraints on the speed of sound in the k-essence model of dark energy. https://doi.org/10.1140/epjc%2Fs10052-024-12547-6

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