Search for the Highest Energy Gamma Rays of Galactic Origin using Telescope Array Low Energy Fluorescence Detectors

Telescope Array (TA), the largest cosmic ray detector in the Northern Hemisphere, studies cosmic rays with energies greater than 1 EeV and as low as 1PeV with the Telescope Array Low Energy extension. 

The leading candidates for the source of Ultra-High Energy (UHE) cosmic rays are large, energetic structures where strong shocks are expected; the most well-known are supernova remnants suspected of generating cosmic rays. However, it is difficult to explain the existence of cosmic rays above 1016 eV because supernovae are not large enough to maintain acceleration for UHE particles.

In pursuit of finding sources of these UHE cosmic rays, photons are of current interest due to the research conducted by The Tibet ASγ experiment, which announced the first detection of photons with energy beyond 1 PeV. These photons were detected from the Crab Nebula and observed by many ground-based gamma-ray experiments. 

With data collected from the Telescope Area over the past ten years, we aim to find photon events of even higher energies starting at 1 PeV. To conduct this research, the focus will be on isolating gamma rays with machine learning methods before plotting the direction of the showers to see if they point back to high-energy galactic events.