Fermi Gamma-ray Space Telescope

Gamma-ray emission from pair-producing gaps at the base of AGN jets

Yajie Yuan
(Alexander Yuran Chen, Huan Yang)


Some active galactic nuclei (AGN), including non-Blazars, show rapid gamma-ray variability that might originate from very close to the black hole. Particularly in low-luminosity AGNs, it is believed that a local region with unscreened electric field could develop in the black hole magnetosphere, accelerating particles and producing high energy gamma-rays that create e± pairs. We carry out time-dependent self-consistent 1D PIC simulations of this process, including inverse Compton scattering and photon tracking. We find a highly time-dependent solution where a macroscopic gap opens quasi-periodically to create e± pairs and high energy radiation. If this gap is operating at the base of the jet in M87, we expect an intermittency on the order of a few rg/c,which coincides with the time scale of the observed TeV flares from the same object. For Sagittarius A* the gap electric field can potentially grow to change the global magnetospheric structure, which may explain the lack of a radio jet at the center of our galaxy.