Caltech Scientists Get Glimpse of Light From Cosmic Web in Deep, Dark Space

Caltech scientists have achieved a significant milestone in cosmic observation, using the Keck Cosmic Web Imager (KCWI) to directly capture light emitted by the cosmic web in the depths of space.

This web, consisting of faint gas streams, acts as the lifeblood of galaxies throughout the universe, supplying them with the necessary resources for star formation. The KCWI, designed by Caltech's Christopher Martin and his team, has provided the first-ever images of the extensive, shadowy filaments connecting galaxies in the darkest realms of space.

Architecture of the Universe

While previous observations had only managed to capture the glow of filaments around luminous cosmic objects known as quasars, the KCWI now offers a direct view of the intricate structure of the cosmic web.

These wispy filaments weave through the vast voids between galaxies, providing them with the essential gas for star formation. This revelation opens new avenues for understanding the intricate processes of galaxy formation and evolution.

"The cosmic web delineates the architecture of our universe," Martin said in a press statement. "It's where most of the normal, or baryonic, matter in our galaxy resides and directly traces the location of dark matter," he added.

The cosmic web plays a pivotal role in defining the structural framework of the universe. It encompasses the majority of regular matter found in galaxies and delineates the distribution of dark matter.

This structure is the result of the universe's initial conditions, set into motion by cosmic inflation and further shaped by gravitational interactions over billions of years. Hence, the study and understanding of the cosmic web is crucial in unraveling the large-scale structure and evolution of the universe.

Using advanced spectrometers to detect hydrogen gas, a fundamental component of the cosmic web, the KCWI is equipped to construct a comprehensive three-dimensional representation of the emissions emanating from these filaments.

This milestone allows a more profound comprehension of the cosmic web's composition and purpose. A primary obstacle in this undertaking was the need to distinguish the faint emissions emitted by the cosmic web from the ambient light originating from Earth's atmosphere and our own galaxy.

Martin devised an innovative technique to remove this undesired interference from the images, fundamentally transforming the study of the universe.

3D Map of the Cosmic Web

Martin explains that they were basically creating a 3D map of the cosmic web. They took spectra for every point in an image at various wavelengths. That, in turn, translates wavelengths to distance.

"With KCRM, the newly deployed red channel of KCWI, we can see even farther into the past," said senior instrument scientist Mateusz Matuszewski (MS '02, PhD '12). "We are very excited about what this new tool will help us learn about the more distant filaments and the era when the first stars and black holes formed."

This development marks a significant stride in observing and comprehending the cosmic web, shedding light on the fundamental processes that shape our universe. The findings of the study were published in the journal Nature Astronomy.