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Upper Limits of Active Galactic Nuclei observed by the MAGIC telescopes

Blazars are Active Galactic Nuclei (AGNs) whose jet is pointed towards the observer. They are usually divided in two sub-classes, depending on the aspect of their optical spectrum. Blazars which present an optical spectrum which lacks of emission lines are categorised as BL Lacertae objects (BL Lacs), while blazars whose optical spectrum shows strong emission lines are named Flat Spectrum Radio Quasars (FSRQs). The majority of blazars who have been found emitting VHE γ-rays are BL Lacs. MAGIC observed and discovered in the VHE γ-ray band many of them in the past years. Nevertheless some of them remained undetected, meaning the signi cance of the signal was lower than 5 σ. For my work of thesis, I gathered information and data from such undetected sources and cre- ated a catalog of 41 sources, 25 of which are BL Lacs. From them, I selected a sample of 5 sources which were observed in 2020-2022 as a starting point for a more complete upper limits study which is in preparation within the MAGIC collaboration. The sources I analysed in detail are: 4FGL- J0955.1+3551, 87GB-225250.5+235403, TXS1700+685, PKS2247-131 and PKS2345-16. From the selected sample of sources I obtained upper limits (ULs) to the light curves (LCs) and spectral energy distributions (SEDs), which can be used in the future to study such sources in a multi- wavelength (MWL) context and de ne a baseline for future studies in case of detection. ULs can in fact, combined with other MWL data, help in understanding the possible emission scenarios of those sources and into de ning strategies to detect them.

gama zracˇenje vrlo visokih energija, aktivne galakticˇke jezgre, astro zika vrlo visokih energija, teleskopi MAGIC, astro zika, astronomija, blazari, crne rupe

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