Angular momentum at null infinity in Einstein-Maxwell theory

Understand

On Minkowski spacetime, the angular momentum flux through null infinity of Maxwell fields, computed using the stress-energy tensor, depends not only on the radiative degrees of freedom, but also on the Coulombic parts.

• However, the angular momentum also can be computed using other conserved currents associated with a Killing field, such as the Noether current and the canonical current.
• The flux computed using these latter two currents is purely radiative.
• A priori, it is not clear which of these is to be considered the true flux of angular momentum for Maxwell fields.