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arXiv · 2508.04312

Probing the Type 3 interacting dark-energy model using matter pairwise velocity

Kin Ho Luo·Ming-chung Chu·Wangzheng Zhang
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Abstract

Dark sector interactions can be explored via the so-called Type 3 model where dark matter and dark energy exchange momentum only, so as to minimize deviations from the $\Lambda$CDM background expansion history. Using N-body simulations, we analyze the imprint of Type 3 model parameters, the momentum exchange coupling constant $\beta$ and the slope of scalar field potential $\lambda$, on large-scale structure observables, particularly the matter pairwise velocity statistics. We find that the effects of $\beta$ ($<0$) and $\lambda$ on the mean matter peculiar pairwise velocity and velocity dispersion are degenerate. Our results highlight the potential of velocity statistics as a probe of dark sector interactions and underscore the importance of disentangling $\beta$ and $\lambda$ in cosmological analyses.

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Kin Ho Luo, Ming-chung Chu, Wangzheng Zhang. 2025-08-06. Probing the Type 3 interacting dark-energy model using matter pairwise velocity. https://doi.org/10.1103/jpt9-hzrg

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