Shine a light: Bursts of star formation reveal a mysterious brightness

The Webb telescope’s image of the Cartwheel Galaxy, which was once shrouded in mystery due to dust – Copyright AFP Aamir QURESHI

When scientists viewed the James Webb Space Telescope’s (JWST) first images of the universe’s earliest galaxies there was a surprise. The young galaxies appeared too bright, too massive and too mature to have formed so soon after the Big Bang.

Now intense flashes of light, not mass, appear to have resolved this puzzle of impossible brightness. New simulations suggest brightness is likely related to irregular patterns of star formation rather than mass. To lower the risk of the scientific community becoming too perturbed, these simulations have proved this without deviating from the standard model of cosmology.

A period that lasted from roughly 100 million years to 1 billion years after the Big Bang, cosmic dawn is marked by the formation of the universe’s first stars and galaxies. Before the JWST launched into space, astronomers knew very little about this ancient time period.

This has changed now that JWST has brought considerable knowledge about cosmic dawn. Sun said. With the huge increase in observing power, researchers can now see physical details about the galaxies and use that solid observational evidence to study the physics to understand what’s happening.

Using the new simulations, a Northwestern University-led team of astrophysicists show how these galaxies likely are not so massive after all. While a galaxy’s brightness is determined by its mass, the new findings suggest that less massive galaxies can glow just as brightly from irregular, brilliant bursts of star formation.

The advanced computer simulations were used to model how galaxies formed right after the Big Bang. The simulations produced cosmic dawn galaxies that were just as bright as those observed by the JWST. The simulations are part of the Feedback of Relativistic Environments (FIRE) project.

The FIRE simulations combine astrophysical theory and advanced algorithms to model galaxy formation. The models enable researchers to probe how galaxies form, grow and change shape, while accounting for energy, mass, momentum and chemical elements returned from stars.

Therefore, this overall finding explains why young galaxies appear deceptively massive, and maintains the current thinking around cosmic dawn.

The findings appear in the journal Astrophysical Journal Letters. The research paper is titled “Bursty Star Formation Naturally Explains the Abundance of Bright Galaxies at Cosmic Dawn”.

Dr. Tim Sandle is Digital Journal’s Editor-at-Large for science news.
Tim specializes in science, technology, environmental, business, and health journalism. He is additionally a practising microbiologist; and an author. He is also interested in history, politics and current affairs.