The gamma‐ray emission from young radio galaxies and quasars. Issue 9 (20th October 2021) - Principe, Giacomo
Abstract: According to radiative models, radio galaxies are predicted to produce γ‐rays from the earliest stages of their evolution onwards. The study of the high‐energy emission from young radio sources is crucial for providing information on the most energetic processes associated with these sources, the actual region responsible for this emission, as well as the structure of the newly born radio jets. Despite systematic searches for young radio sources at γ‐ray energies, only a handful of detections have been reported so far. Taking advantage of more than 11 years of Fermi ‐large area telescope (LAT) data, we investigate the γ‐ray emission of 162 young radio sources (103 galaxies and 59 quasars), the largest sample of young radio sources used so far for a γ‐ray study. We analyzed the Fermi ‐LAT data of each source separately to search for a significant detection. In addition, we performed the first stacking analysis of this class of sources in order to investigate the γ‐ray emission of the young radio sources that are undetected at high energies. In this note, we present the results of our study and we discuss their implications for the predictions of γ‐ray emission from this class of sources.