Anisotropic active Brownian particle with a fluctuating propulsion force.

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• The active Brownian particle (ABP) model traditionally describes self-propelled objects with thermally driven fluctuations.
• Existing models often assume isotropic diffusion and neglect nonthermal noise sources.

Purpose of the Study:

• To develop a two-dimensional model of active Brownian particles with nonthermal noise in the propulsion force.
• To investigate modifications to the standard ABP model under these new conditions.

Main Methods:

• Formulating a two-dimensional model with nonthermal noise acting at a single propulsion point.
• Analyzing the system in the overdamped limit.
• Deriving the diffusion tensor and examining noise-induced drift.

Main Results:

• The model exhibits a coupled diffusion tensor between translational and rotational motion due to fluctuating torque.
• Anisotropic particles show mass-dependent noise-induced drift, persisting even in the overdamped limit.
• These effects contribute to long-time diffusivity independently of the force's application point.

Conclusions:

• Nonthermal noise significantly alters the dynamics of active Brownian particles compared to traditional models.
• Coupled diffusion and persistent drift are key consequences of this noise.
• The findings have implications for understanding synthetic and biological swimmers with flagellar propulsion.