  We discuss some aspects of Pereira et al. (2018) concerning magnetars
described by nonlinear theories of the electromagnetism and make the case for
the Born-Infeld Lagrangian. We focus on the increase of toroidal magnetic
fields in these systems with respect to ordinary magnetars and the subsequent
increase of gravitational wave production. In summary, nonlinear theories of
the electromagnetism would make it more likely for the detection of
gravitational waves with future detectors, which could constrain nonlinear
aspects of electrodynamics not entirely possible on Earth-based particle
accelerators.
