Synchrotron and inverse Compton constraints on Lorentz violations for electrons

We present a method for constraining Lorentz violation in the electron sector, based on observations of the photons emitted by high-energy astrophysical sources. The most important Lorentz-violating operators at the relevant energies are parametrized by a tensor $c^{\nu \mu }$ with nine independent components. If $c$ is nonvanishing, then there may be either a maximum electron velocity less than the speed of light or a maximum energy for subluminal electrons; both these quantities will generally depend on the direction of an electron’s motion. From synchrotron radiation, we may infer a lower bound on the maximum velocity, and from inverse Compton emission, a lower bound on the maximum subluminal energy. With observational data for both these types of emission from multiple celestial sources, we may then place bounds on all nine of the coefficients that make up $c$. The most stringent bound, on a certain combination of the coefficients, is at the $6\times {10}^{-20}$ level, and bounds on the coefficients individually range from the $7\times {10}^{-15}$ level to the $2\times {10}^{-17}$ level. For most of the coefficients, these are the most precise bounds available, and with newly available data, we can already improve over previous bounds obtained by the same methods.