MAGIC Upper Limits on the VHE emission from Flat Spectrum Radio Quasars

Abstract

Blazars are a class of active galactic nuclei (AGN) where the relativistic jet is pointed towards the observer. They are powerful sources of non-thermal radiation from radio to very high energy (VHE, E>100 GeV) gamma-rays. Flat Spectrum Radio Quasars (FSRQs) are a subclass of blazars where there are absorption or emission lines present in the optical spectra. The observed properties of FSRQs are strongly affected by the magnetic field in the accretion disk which changes the UV emission of Broad Line Region (BLR) and infra-red emission from the Dusty Torus. While many (774 as reported in 4FGL-DR2 catalogue [1]) FSRQs have been detected at high energies (HE; E>100 MeV), only a few (9 as of now) could be detected at VHE. In this contribution, we present observations of nine FSRQs performed by Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC)telescopes between 2008 and 2020 with a total observation time of 174 hours. We also include a few observations from the Fermi-LAT, Swift-UVOT, Swift-XRT and optical observations from Kungliga Vetenskapsakademien (KVA) for two sources CTA 102 and B2 2234+28. We also modelled the broad band emission of the sources to look for signatures of absorption in the BLR region and hence to put constraints on the location of the emission region.