Constraints on the Photon Mass from the Galactic Magnetic Field Structure

Abstract

Abstract. The most efficient way to constrain the photon mass (m ph ) is related to observations of largescale magnetic fields in space physics and astrophysics. This approach is based on the change in the Ampere law caused by the finite m ph . In 1990s, a consistent set of MHD equations allowing for the finite m ph has been written and later used to analyze the solar wind data from the Voyager 1 and 2 missions. This lead to an estimate m ph <1.5×10 -51 g, the value currently recommended by the bi-annual compendium of the Particle Data Group. The further progress in constraining the photon mass may come from considering the dynamics of large-scale magnetic fields in astrophysics, in particular, the magnetic field of galaxies. The paper is concerned with related opportunities and challenges, including the problem posed by the simultaneous presence of large-scale and much stronger small-scale magnetic fields. Effects of recycling of the interstellar plasma involving dense molecular clouds, protostars and supernovae explosions are discussed. Possible approaches to pushing the upper bound to a limit well below 10 -51 g are discussed.

Relaxation of relativistic pair plasma in a massive photon field

“…Therefore, based on the aforementioned discussion and the values of scale parameters calculated based on the plasma parameters and photon mass, several potential implications of the current investigation can be realized. For instance, in astrophysical EP plasmas, any observational signatures of magnetic field structures larger than the Compton wavelength can be used to set an upper limit on photon mass (Ryutov 2007(Ryutov , 2010Bhattacharjee 2023). Moreover, the hypothetical Maxwell-Proca stress resulting from a non-zero photon mass in the relaxed state may play a role in the comprehension of flat galactic rotation curves (Ryutov et al 2019) as well as pulsar spin-down.…”

“…The currently recognized upper limit for photon mass is m ν ≤ 10 −49 g and corresponding to this value λ p ≥ 1 au (Adelberger, Dvali & Gruzinov 2007;Particle Data Group 2022). Recently, in the context of magnetized plasmas, some specific solutions to the MHD equations that take into consideration the finite photon mass have been presented and studied in light of the prospect of refining the estimate of the photon mass based on a variety of astrophysical observations (Ryutov 1997(Ryutov , 2007(Ryutov , 2009(Ryutov , 2010. Moreover, Ryutov, Budker & Flambaum (2019) have also investigated the MHD plasma equilibrium to study the effect of Maxwell-Proca electromagnetic stresses on galactic rotation curves (Ryutov et al 2019).…”