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Fermi Gamma ray Space Telescope measurements of spectra, variability timescale, and maximum photon energy give lower limits to the apparent jet powersand, through gammagamma opacity arguments, the bulk Lorentz factors ofrelativistic jets. The maximum cosmic-ray particle energy is limited by thesetwo quantities in Fermi acceleration scenarios. Recent data are used toconstrain the maximum energies of cosmic-ray protons and Fe nuclei acceleratedin colliding shells of GRBs and blazars. The Fermi results indicate that Ferather than protons are more likely to be accelerated to ultra-high energies inAGNs, whereas powerful GRBs can accelerate both protons and Fe to >~ 10^{20}eV. Emissivity of nonthermal radiation from radio galaxies and blazars isestimated from the First Fermi AGN Catalog, and shown to favor BL Lac objectsand FR1 radio galaxies over flat spectrum radio quasars, FR2 radio galaxies,and long-duration GRBs as the sources of UHECRs.

Acceleration of Ultra-High Energy Cosmic Rays in the Colliding Shells of Blazars and GRBs: Constraints from the Fermi Gamma ray Space Telescope