When does an active bath behave as an equilibrium one?

Shubhendu Shekhar Khali; Fernando Peruani; Debasish Chaudhuri

doi:10.1103/physreve.109.024120

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arXiv · 2305.03830

When does an active bath behave as an equilibrium one?

Shubhendu Shekhar Khali·Fernando Peruani·Debasish Chaudhuri

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Abstract

Active baths are characterized by a non-Gaussian velocity distribution and a quadratic dependence with active velocity $v_0$ of the kinetic temperature and diffusion coefficient. While these results hold in over-damped active systems, inertial effects lead to normal velocity distributions, with kinetic temperature and diffusion coefficient increasing as $\sim v_0^\alpha$ with $1<\alpha<2$. Remarkably, the late-time diffusivity and mobility decrease with mass. Moreover, we show that the equilibrium Einstein relation is asymptotically recovered with inertia. In summary, the inertial mass restores an equilibrium-like behavior.

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Shubhendu Shekhar Khali, Fernando Peruani, Debasish Chaudhuri. 2023-05-05. When does an active bath behave as an equilibrium one?. https://doi.org/10.1103/physreve.109.024120

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