Effective temperature of active matter

TL;DR

This paper investigates the concept of an effective temperature in active matter systems, showing it can be defined via fluctuation-dissipation relations and is influenced by motor activity.

Contribution

It introduces a method to define and measure an effective temperature in active matter using fluctuation-dissipation relations and tracer particles.

Findings

Effective temperature is higher than bath temperature.

Effective temperature increases with motor intensity.

Fluctuation-dissipation relation applies to active matter.

Abstract

We follow the dynamics of an ensemble of interacting self-propelled motorized particles in contact with an equilibrated thermal bath. We find that the fluctuation-dissipation relation allows for the definition of an effective temperature that is compatible with the results obtained using a tracer particle as a thermometer. The effective temperature takes a value which is higher than the temperature of the bath and it is continuously controlled by the motor intensity.