A Record-Breaking Cosmic Discovery
Astronomers have identified the most distant and earliest blazar ever observed, featuring a supermassive black hole that is launching intense plasma jets directly toward our planet. This rare celestial object, known as OP 313, offers a unique window into the history of the cosmos, as its light has been traveling across space for 8 billion years. This places our view of the blazar at a time just 5 billion years after the Big Bang.
The Nature of Blazars
Blazars are a specific class of active galactic nuclei (AGNs). These phenomena occur when a supermassive black hole consumes surrounding gas and dust, generating an intense glow that can exceed the brightness of all the stars in its host galaxy combined. While much of the surrounding matter is ingested, some is funneled toward the black hole's poles and ejected as high-speed plasma jets. When these jets are oriented directly along our line of sight, the object is categorized as a blazar.
Transitioning Through 'Cosmic Noon'
The discovery provides critical data regarding a major turning point in the evolution of the universe. According to research team member Axel Arbet-Engels:
«Around 11 billion years ago, the universe experienced a period of peak activity known as the 'cosmic noon,' characterised by an intense rate of star and galaxy formation. When this phase of intense activity slowed down and galaxies began to evolve and mature, the universe entered a calmer phase, which continues to this day.»
How the Black Hole Accelerates Particles
The high-energy gamma rays from OP 313 were first detected in late 2023. Using the Large-Sized Telescope (LST-1) and the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescope in La Palma, Spain, scientists analyzed how these rays traveled across the cosmos. As the gamma rays moved through space, they interacted with the Extragalactic Background Light (EBL)—the combined radiation from all historical stars and galaxies—resulting in the creation of electron-positron pairs.
The team successfully modeled this interaction, confirming that the blazar acts as a massive cosmic particle accelerator. Team member Domenico Della Volpe of the University of Geneva explained the process, known as the leptonic scenario:
«In what is known as the leptonic scenario, electrons have been accelerated to speeds close to the speed of light within a powerful plasma jet ejected by the central supermassive black hole of OP 313. Upon colliding with lower-energy photons surrounding the black hole, the electrons transfer part of their considerable energy to these photons, thereby propelling them to energy levels corresponding to very high-energy gamma rays.»
This research, published in the journal Astronomy & Astrophysics, marks a significant advancement in the study of quasars and the extreme physical processes driving the most powerful events in the observable universe.