Overview
- Astronomers first mapped the Loktak Protocluster with Subaru Telescope's Hyper Suprime-Cam using a narrow filter that picks out Lyman-α emitting galaxies to locate the overdensity.
- Follow-up James Webb Space Telescope imaging shows galaxies inside the Loktak system are on average about 1.4 times larger in optical light than comparable galaxies in typical environments.
- The same galaxies show little size difference in ultraviolet light, which means their central, star-forming regions are similar while their outer, older stellar components grew earlier in the dense region.
- Researchers say the result implies local environment was already affecting galaxy structure roughly 1.2 billion years after the Big Bang and they plan targeted spectroscopy and high-resolution imaging with Subaru PFS/ULTIMATE plus more JWST to confirm membership and kinematics.
- If confirmed in other protoclusters, this wavelength-dependent size difference will force models of galaxy and cluster assembly to account for faster outer-stellar buildup in dense early environments.