Massive galaxy clusters are acting like giant magnifying glasses, making things from the early universe look 8 times bigger than they actually are.
arXiv · March 13, 2026 · 2603.11371
Why it matters
When the first stars lit up the early universe, they created 'bubbles' of light in the darkness. This study found that the gravitational pull of foreground galaxy clusters distorts our view so severely that it inflates the perceived size of these bubbles by over 800%, potentially leading scientists to totally misinterpret how the first stars were born.
From the abstract
The statistical properties of ionisation structures during the Epoch of Reionisation (EoR) provide valuable insights into the formation of the first stars and galaxies. However, statistics such as size distributions of ionisation structures can be affected by gravitational lensing caused by foreground massive structures like galaxy clusters. Hence, to quantify the impacts of lensing by galaxy clusters on ionised Bubble Size Distribution (BSD), we conducted a series of multiple-lens-plane lensing