  We provide the theoretical basis of calorimetry for a class of active
particles subject to thermal noise. Simulating AC-calorimetry, we numerically
evaluate the heat capacity of run-and-tumble particles in double-well and in
periodic potentials, and of systems with a flashing potential. Low-temperature
Schottky-like peaks show the role of activity and indicate shape transitions,
while regimes of negative heat capacity appear at higher propulsion speeds.
From there, a significant increase in heat capacities of active systems may be
inferred at low temperatures, as well as the possibility of diagnostic tools
for the activity of self-motile artificial or biomimetic systems based on heat
capacity measurements.
