The sensitivity of the SST-1M pair of Cherenkov telescopes at very high energies exceeds that of any existing Cherenkov imaging telescope in the world. This surprising news was presented at a conference in Milan by Jakub Jurýšek. At the Institute of Physics, together with his team, he is developing software that allows stereoscopic reconstruction of observed cosmic gamma-ray showers and subsequent imaging of the sources of these gamma photons in space.
What are the main advantages of the SST-1M telescopes in the Czech Republic and why are they focused on the study of gamma-ray sources?
SST-1M telescopes primarily observe cosmic gamma-ray sources in our Galaxy, which emit high-energy photons with energies reaching the level of petaelectronvolts, which is roughly a trillion (a million billion) times the energy of visible light photons. The physical processes behind the emission of this high-energy radiation are still not satisfactorily described and are probably related to the origin of the fast charged particles of galactic cosmic rays, whose origin is difficult to determine directly because of the curvature of their paths in the magnetic field of our Galaxy. The SST-1M telescope sensitivity is optimised for the study of galactic sources of high-energy gamma rays, and they can thus help to solve this long-standing problem in astroparticle physics.
At a conference in Milan, you presented the telescope data analysis results that yielded unexpected discoveries. What aspects of the data did you find most surprising?
At the Milan conference, I presented the results of our observations of just one potential source of the highest energy gamma photons, located near the Dragonfly nebula, which hosts a rapidly rotating neutron star. The gamma-ray image of the object that we were able to reconstruct confirmed the extraordinary angular resolution of our telescopes, which allows us to study the fine structure and details of the nebula in detail. At the same time, the sensitivity of the SST-1M telescopes at very high energies has been shown to exceed that of any existing Cherenkov imaging telescope in the world. This came as a big surprise to us, because the SST-1M telescopes are still in test operation and the location of the Ondřejov Observatory is not ideal due to imperfect atmospheric conditions. However, the low altitude of the observatory, together with the large field of view of the telescopes, has proved to be a key advantage for studying the most energetic gamma photons from space, and we can now get down to the physical interpretation of our observations.
What awaits the two Ondřejov telescopes in the new future?
Although we have achieved excellent results during the ongoing test operation of the telescopes at the Ondřejov Observatory and our observations, mainly focused on galactic sources of cosmic gamma rays, continue, we are planning to move the telescopes to a more suitable location with more stable atmospheric conditions and more clear nights Extensive studies are currently under way to compare possible future sites with respect to the telescope research potential. What is crucial is the optimum altitude of the future observatory. High altitude would result in improved sensitivity at lower energies and hence rapid detection of many interesting sources. On the other hand, low observatory altitude would increase the sensitivity to high energies carrying the most interesting information about cosmic particle accelerators, but at the cost of a longer observation time.
Since his return to FZU from a postdoctoral fellowship at the University of Geneva in 2022, Ing. Mgr. Jakub Juryšek, Ph.D. leads an international group focused on data analysis and telescope calibration. He started working on the SST-1M project in 2018, when his PhD thesis involved optimizing the simulations of the showers to exactly match the measured data.