LST-1 and MAGIC telescopes shatter distance record for the very high-energy blazar OP 313

On August 15, the CTAO LST Collaboration and MAGIC Collaboration published a study in Astronomy & Astrophysics detailing observations of OP 313, the most distant very-high-energy blazar ever recorded. The Large-Sized Telescope (LST-1) and MAGIC telescopes at Roque de los Muchachos Observatory in La Palma, Spain, conducted in-depth observations of the source.

OP 313, a flat-spectrum radio quasar, is classified as one of the brightest and most powerful emitters in the universe. The observations revealed a flux of very-high-energy photons originating from a distance of approximately 8 billion light-years. By analyzing these gamma rays, scientists gained insights into the diffuse extragalactic background light (EBL) and particle acceleration processes within the galaxy.

Blazars, such as OP 313, are highly active galactic nuclei powered by supermassive black holes and emit extremely bright light. In December 2023, the LST-1 had already detected OP 313 at very high energies. The joint observations from the LST-1 and MAGIC telescopes provided stringent constraints on the EBL density and characterized the flux variability.

The intense gamma-ray emission was attributed to a dense population of relativistic electrons in the massive jet launched by the galaxy's supermassive black hole. These electrons, accelerated to near-light speed, transferred part of their immense energy to lower-energy light surrounding the black hole, boosting them into very-high-energy gamma rays.