The LST-1 telescope in the Cherenkov Telescope Array “made” its first scientific discovery. Using a telescope, astronomers detected strong radiation from quasar OP 313, making this object the most distant high-energy active galaxy we know of.

Active galaxies are galaxies whose cores emit large amounts of energy due to processes occurring around their supermassive black holes. Quasars are one type of active galactic nuclei.

They are rarely detected in the high energy range because the material of the accretion disk attenuates high-energy radiation: photons with the highest energy are best absorbed by them. In addition, the further away the object is, the greater the influence of the extragalactic background light (EBL), its high-energy radiation “flying” at us. Extragalactic background light is the total radiation of objects outside our Milky Way galaxy.

The LST-1 telescope performs observations in the range of 20 to 150 gigaelectron volts, where high-energy streams are less susceptible to the influence of background light. At the beginning of the month, on December 1, 2023, astronomers working with the LAT telescope as part of the Fermi Gamma Ray Telescope reported a change in the activity of the source OP 313 – increased gamma radiation.

The LST-1 telescope observed the object for four days, from December 10 to 14. Scientists have “captured” more than 100 gigaelectron volts of radiation. In other words, the energy of these photons is billions of times greater than the energy of visible light. Thus, OP 313 became tenth in the list of known high-energy quasars.

With a maximum redshift of 0.997, it is also the most distant similar object and the second source of high-energy radiation. A redshift of 0.997 means that light from this quasar has been heading toward us for about eight billion years.

The important thing is not even the discovery, but the fact that the LST-1 telescope, now commissioned, has proven its effectiveness. It is the prototype of the Large Size Telescope (LST), one of three types of telescopes in the Cherenkov Telescope Array; It is an international project that aims to create a new generation of instruments for the study of a wide range of gamma radiation. Some will be located in the Northern Hemisphere, some in the Southern Hemisphere.

The LST-1 prototype is a representative of the northern group of telescopes where astronomers will primarily search for low-energy extragalactic objects. Once commissioned, it will be the first in the Cherenkov Telescope Array. In addition to high sensitivity, an important feature of these telescopes is their mobility. They can change position in less than 20 seconds, allowing the study of transient events such as gamma-ray bursts. Therefore, a number of new discoveries are expected.