Suppression of Inverse Compton Radiation from Relativistic Magnetic Reconnection by Seed Photon Anisotropy

Relativistic magnetic reconnection powers high-energy flares in astrophysical systems such as blazar jets and accreting black hole coronae. The inverse Compton (IC) process, where relativistic electrons upscatter soft seed photons to higher energies, is responsible for the most energetic component of the flaring spectra. We investigate how seed-photon anisotropy modifies the IC output of relativistic reconnection. For this task, we developed a code that calculates the angular and spectral content of Compton emission from arbitrary distributions of relativistic electrons and ambient photons. We take electron distributions from snapshots of particle-in-cell reconnection simulations and specify various functional forms for the background radiation. Reconnection-generated electron distributions develop focused beams of energetic particles. Illuminated isotropically, each beam produces an equally focused IC flare. However, when a particle beam is aligned even modestly with a directed seed photon field, we find the power and mean spectral energy of its flare can be suppressed by orders of magnitude. This result may have implications for reconnection-powered flares in, e.g., blazar jets, where the external seed photons can be highly anisotropic.