A groundbreaking study published in Nature Astronomy reports a new method for exploring the distant universe through a special type of stellar explosion. The research, conducted by an international team including Andreja Gomboc from the Center for Astrophysics and Cosmology, University of Nova Gorica, focuses on Fast X-ray Transients (FXT)—mysterious bursts of X-ray radiation that typically last only a few minutes.
On March 15, 2024, the Einstein Probe satellite detected the X-ray source EP240315A, associated with a gamma-ray burst GRB240315C observed by the Swift and Konus-Wind satellites, as well as the optical source AT2024eju detected by ATLAS telescopes on Earth. The precise location allowed follow-up observations with instruments such as the Very Large Telescope (VLT) in Chile and GranTeCan on La Palma.
The explosion occurred when the universe was less than 10% of its current age, meaning the light traveled 12.5 billion years to reach Earth. The energy released exceeded that of the Sun over its entire 10-billion-year lifetime. Although FXTs last longer and emit primarily in X-rays rather than gamma rays, the study shows that some FXTs may actually be distant gamma-ray bursts observed differently due to their extreme distance.
Interestingly, observations revealed very little hydrogen around EP240315A, shedding light on early-universe conditions during reionization when most hydrogen absorbed ultraviolet light. About 10% of the UV light from the host galaxy escaped, marking the most distant event with such a measurement.
The Einstein Probe, developed by the Chinese Academy of Sciences, European Space Agency, and Max Planck Institute for Extraterrestrial Physics, has detected around 20 similar FXTs since January 2024. The Center for Astrophysics and Cosmology, University of Nova Gorica, is Slovenia’s largest astrophysics research group, contributing to international projects including Cherenkov Telescope Arrays, Pierre Auger Observatory, Vera Rubin Observatory, and ESA’s Gaia satellite.
Source: University of Nova Gorica
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