Palestrante
Descrição
Active galactic nuclei are one of the main candidates for UHECR's accelerators. Comparing theoretical expectations with observational data is essential to test this assumption. However, using the gamma-ray luminosity ($L_\gamma$) as a proxy for the UHECR luminosity ($L_{cr}$), several works have weakened this hypothesis. The main issues are 1) the excess of secondaries during the propagation that make the energy spectrum hard to fit; and 2) a poor description of the arrival directions, particularly a fortuitous dipole. Both problems are related to a dominant contribution from distant objects, especially Markarian 421 at ~130 Mpc. This work reviews the motivations behind using $L_\gamma$ as a proxy for $L_{CR}$. Comparing theoretical predictions for the UHECR acceleration in AGN jets and the origin of the $\gamma$-ray radiation, we show that $L_{\gamma}$ should be used carefully to weight the UHECR flux. Considering the differences between blazars and radio galaxies can considerably increase the agreement between the predictions and the data.
