Prof. Alessandro D.A.M. Spallicci, Non-Maxwellian electromagnetism in astrophysics and cosmology

by Prof. Prof. Alessandro D.A.M. Spallicci (Université d’Orléans, Observatoire des Sciences de l’Univers en Région Centre Centre Nationale de la Recherche Scientifique, Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Orléans Chaire Française, Universidade do Estado do Rio de Janeiro)

Thursday 23 May 2019, 14:30 → 16:30 Europe/Rome

0M05 (Dipartimento di Fisica, M. S. Angelo )

Inexplicable observations on the Universe prompt cosmologists to propose either ad hoc explanations as dark matter and energy maintaining general relativity entirely valid, or to propose alternatives to general relativity, without evoking dark ingredients [ACL 71]. But for the former investigation track, experimental confirmations are missing, and for the latter general relativity continues to predict observations with exactitude.

Confronted with this dichotomy, and with a multi-parametrised cosmology, we consider legitimate also to investigate on the nature of the main messenger from the Universe, light, that we stick so far to interpret as Maxwellian. But the photon in the Standard Model singles out as the only massless free particle, and the waves emerge from a linear theory of the XIX century. What if light were to be described by a different theory?

Results on testing non-Maxwellian electromagnetism (either massive initiated by de Broglie and Proca or non-linear by Born and Infeld, Heisenberg and Euler) include setting photon mass upper limits from the modified Ampère law in solar wind through the Cluster spacecraft [ACL 64], or from frequency dependent group velocities of photons from Fast Radio Bursts [ACL 63,69]. Future nanosatellite swarms operating in a new radio-astronomy window, 10 KHz - 10 MHz [ACL 68], might provide a significant contribution.

De Broglie formulated a photon mass already in 1922 and in the later year he estimated such mass to be lower than 10-53 kg, surprisingly close to the actual limits established by the Particle Data Group.

Meanwhile, an effective photon mass emerges when Lorentz symmetry is broken in (possibly Super-Symmetrised) Standard Model Extension, as well as bi-refringence and energy variation [ACL 67,73,75].

Non-linear effects as polarisation dependent frequency shifts in strong magnetic field in Magnetars have been analysed too [ACTI 53].

We are now progressing in modelling a general non-linear electromagnetism Lagrangian and as for Standard Model Extension [ACL 75] look into the non-conservation of the energy-momentum tensor of the light wave. The latter, transferred into photon energy variation, produces additional, non-expansion related, frequency shifts. Will be they significant?