We study the local entropy production rate and the local entropy flow in active systems composed of noninteracting run-and-tumble particles in a thermal bath. After providing generic time-dependent expressions, we focus on the stationary regime. Remarkably, in this regime the two entropies are equal and depend only on the distribution function and its spatial derivatives. We discuss in detail two case studies relevant to real situations. First, we analyze the case of space-dependent speed describing photokinetic bacteria, cosidering two different shapes of the speed, namely piecewise constant and sinusoidal. Finally, we investigate the case of external force fields, focusing on harmonic and linear potentials, which allow analytical treatment. In all investigated cases, we compare exact and approximated analytical results with numerical simulations.

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• Nonequilibrium statistical mechanics
• Stochastic processes
• Living matter & active matter
• Nonequilibrium systems
• Self-propelled particles
• Fokker–Planck equation
• Langevin equation