Signatures of motor susceptibility in the dynamics of a tracer particle in an active gel

Abstract

We study a model for the motion of a tracer particle inside an active gel, exposing the properties of the van Hove distribution of the particle displacements. Active events of a typical force magnitude give rise to non-Gaussian distributions, having exponential tails or side-peaks. The side-peaks appear when the local bulk elasticity of the gel is large enough and few active sources are dominant. We explain the regimes of the different distributions, and study the structure of the peaks for active sources that are susceptible to the elastic stress that they cause inside the gel. We show how the van Hove distribution is altered by both the duty cycle of the active sources and their susceptibility, and suggest it as a sensitive probe to analyze microrheology data in active systems with restoring elastic forces.

arXiv comment4 pages, 4 figures and supplemental information (5 pages, 4 figures)

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• The active trap model
• Condensation transition in the late-time position of a Run-and-Tumble particle
• Universal Properties of a Run-and-Tumble Particle in Arbitrary Dimension
• Dynamics and escape of active particles in a harmonic trap
• Tracer dynamics in one dimensional gases of active or passive particles
• Run-and-Tumble particle in inhomogeneous media in one dimension
• Chemically symmetric and asymmetric self-driven rigid dumbbells in 2D polymer gel
• Active gels, heavy tails, and the cytoskeleton
• Active velocity processes with suprathermal stationary distributions and long-time tails
• Dichotomous acceleration process in one dimension: Position fluctuations
• First-order condensation transition in the position distribution of a run-and-tumble particle in one dimension
• Non-monotonic displacement distribution of active random walkers