  We follow the dynamics of an ensemble of interacting self-propelled
semi-flexible polymers in contact with a thermal bath. We characterize
structure and dynamics of the passive system and as a function of the motor
activity. We find that the fluctuation-dissipation relation allows for the
definition of an effective temperature that is compatible with the results
obtained by using a tracer particle as a thermometer. The effective temperature
takes a higher value than the temperature of the bath when the effect of the
motors is not correlated with the structural rearrangements they induce. Our
data are compatible with a dependence upon the square of the motor strength
(normalized by the average internal force) and they suggest an intriguing
linear dependence on the tracer diffusion constant times the density of the
embedding matrix. We show how to use this concept to rationalize experimental
results and suggest possible innovative research directions.
