Magnetogenesis from isocurvature initial conditions
  The generation of magnetic fields is a natural consequence of the existence
of vortical currents in the pre-recombination era. This has been confirmed in
detail for the case of adiabatic initial conditions, using second-order
Boltzmann solvers, but has not been fully explored in the presence of
isocurvatures. In this work, we use a modified version of the second-order
Boltzmann code SONG to compute the magnetic field generated by vortical
currents for general initial conditions. A mild enhancement of the generated
magnetic field is found in the presence of general isocurvature modes, when
compared to the adiabatic case. A particularly interesting case is that of the
compensated isocurvature mode, for which the enhancement increases by several
orders of magnitude due to the observationally allowed large amplitude of those
modes. We show in this particular case how these compensated modes can
influence observables at second order, such as the magnetic fields, and produce
interesting effects which may be used to constrain these modes in the future.
