High-energy Emission Component, Population, and Contribution to the Extragalactic Gamma-Ray Background of Gamma-Ray-emitting Radio Galaxies

In this study, we systematically studied the X-ray to GeV gamma-ray spectra of 61 {\it Fermi} Large Area Telescope (LAT) detected radio galaxies. We found an anticorrelation between peak frequency and luminosity in high-energy spectral component galaxies, similar blazars. With sample, also constructed a function (GLF) gamma-ray-loud that blazar-like GLF shapes can reproduce their redshift distribution, but log$N$-log$S$ relation prefers models with more low-$z$ This indicates many By utilizing our latest GLF, contribution galaxies extragalactic background is be 1--10\%. further investigated nature Compared or flux-limited galaxy samples, selected sample tends lack high power like FR-II only $\sim$10\% are loud. Radio may contribute cosmic MeV comparable blazars if gamma-ray-quiet have Cen A, small flux ratio.