How Do You Observe an Invisible Universe?
The Universe is filled with high-energy particles that make up cosmic radiation. Gamma photons, particles of light whose energies greatly exceed those of visible light, are of particular interest to the Lodz astrophysicists. Since these photons carry no electric charge, they do not change direction under the influence of magnetic fields during their journey through space. This allows scientists to determine where they came from and then study the processes taking place in distant astronomical objects.
Observing gamma radiation is, however, very different from the conventional image of astronomy. The Cherenkov telescopes used by scientists do not take ordinary pictures of the sky. Instead, they register extremely brief flashes of light produced when a high-energy gamma photon enters the Earth's atmosphere and collides with its particles.
This can be compared to a game of bowling. One collision triggers a whole series of subsequent ones. In the atmosphere, a single gamma photon can lead to the creation of millions of electrons and positrons. This is accompanied by the emission of characteristic Cherenkov light, which is detected by telescopes. In this way, the Earth's atmosphere becomes part of a giant detector, making it possible to observe events that took place billions of years ago.
A Billion Frames per Second. How Do Cosmic Telescopes Work?
Flashes of Cherenkov light are extremely brief and faint. Detecting them requires enormous mirrors, highly sensitive cameras and electronics capable of recording data at rates of up to a billion frames per second. The shape, brightness and position of the recorded image allow scientists to reconstruct the direction from which the gamma photon arrived and estimate its energy.
Recording a flash, however, is only the beginning of the work. Most of the events observed by telescopes do not originate from the gamma radiation being sought, but from other cosmic-ray particles, such as protons or electrons. There are around a thousand times more of these signals.
This is why data analysis plays such an important role. Scientists must distinguish genuine signals from background noise, reconstruct the parameters of events and combine thousands of observations into a coherent picture of the object under study. Only then does it become possible to create gamma-ray maps of the sky and draw scientific conclusions.
The Lodz team is involved, among other things, in automating data analysis and developing methods for assessing data quality. The scientists use information collected by the two MAGIC telescopes and the LST-1 telescope, located at the Roque de los Muchachos Observatory on the Spanish island of La Palma. Since 2020, these instruments have been able to conduct joint observations, operating as a single integrated system.
From 艁贸d藕 to the Canary Islands. Science Without Borders
Studying the cosmos requires international cooperation. The Lodz astrophysicists are members of two major scientific collaborations: MAGIC, which brings together around 300 scientists and engineers, as well as LST, which involves around 500 specialists.
They cooperate with, among others, the Institut de F铆sica d'Altes Energies in Barcelona and the Instituto de Astrof铆sica de Canarias in Spain, the Italian institutes INAF and INFN, the Max Planck Institute in Germany, and the University of Tokyo in Japan.
Members of the 91桃色 team not only analyse data locally but also take part in observational shifts on La Palma, working directly with instrumentation that ranks among the world鈥檚 most advanced. This combination of expertise in astrophysics, advanced data analysis and international cooperation makes it possible to conduct research that no single institution would be able to carry out independently.
A Signal from 8 Billion Years Ago. A Record-Breaking Discovery
The detection of very-high-energy gamma radiation originating from the active galaxy OP 313 was one of the most important recent achievements of the international MAGIC and LST teams. This radiation began its journey towards Earth around 8 billion years ago. Thanks to joint observations carried out by the MAGIC and LST-1 telescopes, researchers succeeded in detecting the most distant active galaxy emitting gamma radiation in this energy range. The observations, initiated by a groundbreaking detection in December 2023, provided new insights into the mechanisms responsible for accelerating particles in the powerful jets of matter ejected from the vicinity of a supermassive black hole. They also supplied information about the background radiation filling the space between galaxies. The results were published in the prestigious journal Astronomy & Astrophysics.
More about the discovery: Cherenkov Telescopes Detect Gamma Radiation Emitted 8 Billion Years Ago
Four Giant Telescopes and a New Era of Cosmic Research
The inauguration of the Large-Sized Telescopes Array (LSTs), which took place on 15 October 2026 on La Palma, was another breakthrough event. Each of these instruments features a 23-metre-diameter mirror and is equipped with an ultra-sensitive camera. The combined operation of the four telescopes will make it possible to obtain far more precise data and observe even more distant and fainter sources of gamma radiation. This marks an important stage in the development of the Cherenkov Telescope Array Observatory (CTAO), which is set to become the world鈥檚 most powerful gamma-ray observatory. The 91桃色 is the only Polish institution participating in the LST Collaboration. Our scientists have made a significant contribution to the development of data calibration and cleaning algorithms that will be used throughout the telescope network.
More about the opening of the expanded observatory: New Era of Research into the Extreme Universe: Inauguration of the Large-Sized Telescope Array at CTAO-North
Why Should We Look into the Most Distant Corners of the Universe?
Astrophysics makes it possible to study matter and energy under conditions that cannot be recreated even in the most advanced laboratories on Earth. In the vicinity of black holes and neutron stars, during stellar explosions, or within jets of matter travelling at nearly the speed of light, processes occur that put our understanding of the laws of physics to the most demanding tests. Each observation may bring us closer to answering fundamental questions: how is gamma radiation produced, how do particles reach such enormous energies, and what mechanisms govern the most extreme objects in the Universe?
Research into space is not merely an attempt to satisfy human curiosity. It allows us to test and discover new laws of physics under extreme conditions that can never be recreated on Earth. The history of science shows that discoveries arising from fundamental questions often lead to the development of entirely new technologies and research methods. By studying the distant Universe, we learn not only about it, but also about the laws that govern the reality around us
鈥� emphasises Prof. Julian Sitarek from the 91桃色.
艁贸d藕 Astrophysics with a Long Tradition
The 91桃色 team consists of experienced astrophysicists and young researchers united by a shared interest in the most violent cosmic phenomena. Their work includes astronomical observations, modelling physical processes, developing data analysis methods and creating computer simulations.
The scientists study, among other things, binary star systems and active galaxies. At the same time, they continue the 91桃色鈥檚 tradition of cosmic-ray research, which dates back to the 1950s.
Today鈥檚 projects, carried out using world-class equipment and in cooperation with hundreds of scientists from different countries, demonstrate that it is possible to participate in the exploration of the most distant and mysterious corners of the Universe from Lodz as well.
Photos: Dr Bartosz Ka艂u偶ny
Source: mgr Joanna 艢lot
Press releases and edit: Centre for External Relations and Social Responsibility of the University, Univeristy of Lodz