Some Additional Bounds on the Photon Charge
  We have arrived at tight constraints on the photon charge, giving comparable bounds, one based on the dominance by dark energy at the present epoch, and the other based on the requirement that early universe nucleosynthesis not be affected by any residual electrostatic energy due to any miniscule charge on the radiation photons in that era. Limits have also been arrived at from synchrotron and IC effects. We have also set limits on the charge based on the properties of black holes. The set of constraints arrived at in this paper are consistent with those predicted by other authors. 
C. Sivaram (1) and Kenath Arun (2) ((1) Indian Institute of   Astrophysics, Bangalore, India; (2) Christ Junior College, Ban...