'Using gamma-ray bursts': Astronomers find cosmic superstructure is bigger and nearer to Earth
Gamma-Ray Bursts
Astronomers have revised the scale of the Hercules–Corona Borealis Great Wall using gamma-ray bursts (GRBs) — the most powerful known cosmic explosions. The bursts helped trace the structure’s outline more accurately than previous studies.
Bigger and Closer Than Previously Estimated
New findings suggest that the structure is not only larger than earlier measurements indicated but that some of its regions lie closer to Earth than previously thought. These adjustments were made possible by examining updated GRB data.
Understanding the Hercules
The structure is a supercluster — a vast network of galaxies. Though its name suggests it lies only within the constellations Hercules and Corona Borealis, it spans a much wider portion of the sky, including areas from Boötes to Gemini.
Initial Discovery and Updated Analysis
Originally identified in 2014 by researchers István Horváth, Jon Hakkila, and Zsolt Bagoly, the team has now refined its measurements by analysing a set of 542 GRBs. These were primarily gathered by NASA's Fermi and Swift observatories over the last two decades.
Challenge to Cosmological Assumptions
The size of the structure — now estimated to extend beyond 10 billion light-years — poses a challenge to the cosmological principle, which assumes a uniform distribution of matter on large scales. Structures of this magnitude may not fit within some models of cosmic evolution.
Why GRBs Are Effective Tools
GRBs are associated with dying massive stars or merging neutron stars and can be used to infer the presence of distant galaxies. Their brightness makes them observable across large distances, even when host galaxies are not detectable directly.
Further Observations and Future Missions
The research team acknowledges current limitations due to GRB sample size and identification accuracy. They highlight the importance of upcoming missions, particularly ESA’s proposed THESEUS project, which could significantly expand the GRB database and offer a clearer understanding of such large-scale cosmic structures.