Laboratoire Collisions Agrégats Réactivité - UMR5589

In this letter we calculate the energy loss of a highly magnetized neutron
star due to Quantum Vacuum Friction (QVF). Taking into account one-loop
corrections in the effective Heisenberg-Euler Lagrangian of the light-light
interaction, we derive an analytic expression for QVF allowing us to take
into account a magnetic field at the surface of the star as high as
T. In the case of magnetars, with magnetic fields above the QED critical field, we show that the QVF is the dominating energy loss process.
This has important consequences, in particular for the inferred value of the magnetic field. This also indicates the need for independent measurements of magnetic field, energy loss rate, and the braking index in order to fully characterize magnetars.