According to Phys.org, an international team led by the University of Oxford has achieved a world-first by creating plasma “fireballs” using the Super Proton Synchrotron accelerator at CERN in Geneva. The research, published in PNAS, focused on studying plasma jets from blazars—active galaxies powered by supermassive black holes that emit near-light-speed particle beams toward Earth. Scientists investigated why TeV gamma rays from these jets scatter off intergalactic light to create electron-positron pairs that should generate detectable lower-energy gamma rays, yet these secondary emissions remain missing from telescope observations. The team used CERN’s HiRadMat facility to generate electron-positron pairs and send them through meter-long ambient plasma, creating a scaled laboratory analog of blazar-driven cascades. The experiment revealed that beam-plasma instabilities were too weak to explain the missing gamma rays, instead supporting the hypothesis that weak intergalactic magnetic fields deflect the radiation. This laboratory breakthrough opens new avenues for understanding cosmic phenomena through terrestrial experiments.
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The Laboratory Astrophysics Revolution
What makes this research particularly significant is how it bridges the gap between astronomical observation and experimental physics. Traditional astrophysics relies heavily on passive observation—we watch what happens in the universe and try to deduce the underlying physics. This experiment flips that approach by actively recreating cosmic conditions in a controlled laboratory setting. The team essentially built a miniature version of intergalactic space within CERN’s facilities, allowing them to test hypotheses that would otherwise remain speculative. This represents a paradigm shift in how we study cosmic phenomena, moving from purely observational science to experimental verification of astrophysical theories. The ability to create and manipulate relativistic plasma conditions on Earth gives researchers unprecedented control over variables that are impossible to manage when studying distant astronomical objects.
The Primordial Magnetic Field Mystery
The findings point toward a much deeper cosmological puzzle: the origin of intergalactic magnetic fields. If these fields are indeed deflecting the gamma rays as the research suggests, they must be primordial in nature—relics from the universe’s earliest moments. This challenges current understanding of the early universe, which is believed to have been extremely uniform following the Big Bang. The presence of organized magnetic fields from that era implies processes we haven’t yet accounted for in our cosmological models. These fields could have been generated during cosmic inflation, phase transitions in the early universe, or through processes involving dark matter or other beyond-Standard-Model physics. The strength and configuration of these fields, while weak by laboratory standards, would have played a crucial role in shaping the large-scale structure of the universe we observe today.
The Engineering Behind Cosmic Recreation
Creating laboratory-scale analogs of cosmic phenomena requires extraordinary precision in scaling relationships. The team had to ensure that the dimensionless parameters governing plasma behavior in their experiment matched those in actual blazar jets, despite the vast difference in physical scales. This involves maintaining similarity in factors like the plasma beta (ratio of thermal to magnetic pressure), magnetization parameters, and Reynolds numbers. The use of CERN’s Super Proton Synchrotron and HiRadMat facility provided the necessary conditions to achieve relativistic electron-positron beams with energies and densities that properly scaled to astrophysical counterparts. The meter-long plasma chamber, while small by terrestrial standards, represented a significant volume for studying plasma instabilities under controlled conditions. This technical achievement demonstrates how advanced particle accelerators can be repurposed for astrophysical research beyond their original design parameters.
Next-Generation Observational Capabilities
The research highlights the critical need for more sensitive gamma-ray observatories to test these findings further. The upcoming Cherenkov Telescope Array Observatory (CTAO) represents exactly the type of instrument needed to advance this research. With significantly improved angular resolution and sensitivity compared to current telescopes like Fermi, CTAO should be able to detect the faint, diffuse gamma-ray background that current instruments miss. If the laboratory results are correct, CTAO might detect the signature of magnetic deflection through specific polarization patterns or energy distributions in the gamma-ray spectrum. This creates a powerful feedback loop between laboratory experiments and astronomical observation—lab results inform what to look for in the sky, while astronomical data validates or challenges laboratory findings.
Implications for Understanding Cosmic Evolution
Beyond solving the specific mystery of missing gamma rays, this research has broader implications for our understanding of cosmic structure formation. Magnetic fields play crucial roles in numerous astrophysical processes, from star formation to galaxy evolution. If weak intergalactic magnetic fields are indeed ubiquitous, they could influence how cosmic rays propagate, how galaxies form, and even how large-scale structures develop. The findings suggest that magnetic fields may be more fundamental to cosmic evolution than previously appreciated, potentially acting as a hidden architecture shaping the visible universe. This research also demonstrates how studying extreme astrophysical objects like blazars can reveal fundamental properties of the intergalactic medium that would otherwise remain invisible to our telescopes.
A New Approach to Fundamental Physics
Perhaps the most exciting aspect of this research is how it demonstrates the power of interdisciplinary collaboration. By bringing together particle physicists, plasma physicists, and astrophysicists, the team created a novel methodology for testing fundamental physics. This approach could be applied to other cosmic mysteries, such as the nature of dark matter, the origin of ultra-high-energy cosmic rays, or the physics of neutron star mergers. The ability to recreate extreme cosmic conditions in terrestrial laboratories represents a new frontier in physics research, one that complements both theoretical work and astronomical observation. As Professor Subir Sarkar noted, this “adds a novel dimension to the frontier research being done at CERN,” showing how established facilities can be leveraged for entirely new scientific purposes beyond their original mandates.
