A simple derivation of the Gertsenshtein effect

• Published in: PHYSICS OF THE DARK UNIVERSE Vol. 40; p. 101187
• Main Authors: Palessandro, Andrea, Rothman, Tony
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2023
• ISSN: 2212-6864; 2212-6864
• DOI: 10.1016/j.dark.2023.101187

As shown by Gertsenshtein in 1961, an external magnetic field can catalyze the mixing of graviton and photon states in a manner analogous to neutrino-flavor oscillations. We first present a straightforward derivation of the mechanism by a method based on unpublished notes of Freeman Dyson. We next extend his method to include boundary conditions and retrieve the results of Boccaletti et al. from 1970. We point out that, although the coupling between the graviton and photon states is extremely weak, the large magnetic fields around neutron stars ∼1014 G make the Gertsenshtein effect a plausible source of gravitons. We also point out that axion–photon mixing, a subject of active current research, is essentially the same process as the Gertsenshtein effect, and so the general mechanism may be of broad astrophysical and cosmological interest.