Thesis defense of Lena Linhoff

The radio galaxy 3C 84 is a well-studied source of radio emission and was detected as NGC 1275 also in the MeV/TeV regime by gamma-ray detectors like MAGIC and Fermi-LAT. It is still unclear where and how the gamma-ray emission is produced. In this thesis, I will confine possible emission sites and exclude the region near the black hole as the origin of the gamma-ray production. For this aim, I investigate the optical depth of the broad-line region using data published by MAGIC and Fermi-LAT. Furthermore, a cross-correlation study is performed to find a possible correlation between the light curves of the two radio components in 3C 84 detected by the VLBA and the gamma-ray light curve measured by Fermi-LAT. A significant correlation between the core component and the gamma-ray emission is found, which is in line with the results I derive from analyzing the optical depth of the broad-line region. For the first time, I perform a long-term analysis of NGC 1275 for four years of MAGIC data, which reveals a short flare at the beginning of 2017 and a very low state of activity since then. To perform this long-term analysis, the software framework autoMAGIC was developed in the course of this thesis. autoMAGIC enables fully automatic and reproducible analyses of long-term data and can be used for the automatic processing of MAGIC data in the future.

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