How much is the maximum frequency of gamma rays that is measured until now?
Answer Dear Omid, Thank you for your very good question about the highest energy gamma-rays. Historically, all particles with frequencies greater than about 1019 Hertz (or about 50,000 electron Volts (5×104 eV) where a typical optical photon carries 2-3 eV) are called gamma-rays. Theoretically, there is no hard limit to the energy that a gamma-ray can have. However, there are a number of practical considerations that one needs to take into account involving both astrophysical sources and basic physics. Before we address this, however, let’s tackle the question about the highest energy gamma-rays yet detected. The highest energy measurements of gamma-rays are accomplished using ground-based instrumentation which also measure cosmic rays. Reliable detections of very high energy gamma-ray radiation from individual astrophysical sources, specifically from a couple of active galaxies and from the Crab Nebula, have extended up to about 1027 Hz (5 x 1012 eV). Aside from these individual sourc
