The James Webb Space Telescope is already helping researchers fine-tune their classifications of distant galaxies – adding significant speed and detail to analysis that has been underway for decades.
Research led by Viraj Pandya, a NASA Hubble Fellow at Columbia University in New York, focused on several thousand galaxies in Webb’s Cosmic Evolution Early Release Science (CEERS) Survey that existed when the universe was 600 million to 6 billion years old. The team found that most distant galaxies do not look like the more familiar spiral and elliptical galaxies that lie closer to Earth.
Pandya’s team pinpointed four main classifications, shown illustrated above as both 3D objects and cross sections. They are ordered from least to most frequent.
At top left, Webb’s survey shows a classification that’s rare in the early universe, but common today: Galaxies that are shaped like spheres or volleyballs.
At top right are flattened circular disks or frisbees, which are only slightly more common.
The galaxy shapes that dominate during this early period look flat and elongated, like surfboards, shown at bottom left, or pool noodles, bottom right. This pair of classifications make up approximately 50 to 80% of all distant galaxies they’ve studied so far – a surprise, since these shapes are uncommon nearby.
The advances in astronomers’ classifications are owed to Webb’s sensitivity, high-resolution images, and specialization in infrared light. The astronomical community will also need to fully classify more distant galaxies with much larger sample sizes from Webb and other telescopes before settling on any firm groupings.
“By continuing this research, we and other teams will be able to improve our understanding of the intrinsic structure of galaxies at this point in the history of the universe,” explained co-author Elizabeth McGrath, an associate professor at Colby College in Waterville, Maine. “By eventually combining information from multiple datasets, we will better understand galaxy shapes over all of cosmic time.”
NASA, ESA, CSA, Joseph Olmsted (STScI)
Viraj Pandya (Columbia), Haowen Zhang (University of Arizona), Lucy Reading-Ikkanda (Simons Foundation)