Cosmic web fuels stars and supermassive black holes
Deborah Byrd in SPACE | October 6, 2019

Astronomers probed the cosmic web, a large-scale structure composed of massive filaments of galaxies separated by giant voids. They found the filaments also contained significant amounts of gas, believed to help fuel the galaxies’ growth.


Astronomers now think of our universe as a cosmic web, composed of massive filaments of galaxies separated by giant voids. We don’t know in detail what this cosmic web is like. Most of our exploration of it has come via computer models, in particular the cold dark matter model for galaxy formation, the model currently favored by most cosmologists. The model shows that filaments in the cosmic web – essentially long threads of gas – provide the fuel for the intense formation of stars and supermassive black holes. On October 4, 2019, astronomers said they’ve now obtained images of a particularly bright portion of the cosmic web, including threads of gas extending over 3 million light-years. They say it’s the first time the cosmic web has been imaged in such detail on that large a scale. And behold, the observations agree with what has been theorized. The region where these enormous filaments meet is home to an “exceptional number,” they said, of supermassive black holes and starbursting galaxies with very active star formation.

According to current theories of galaxy formation, such intense activity can only be triggered and sustained over time if large amounts of gas are funneled into the assembling cluster from the surrounding regions.

The group found that the detected filaments in the cosmic web contained a significant reservoir of gas. This gas, they expect, is what helps fuel the continued growth of galaxies in this region.

These astronomers are from the RIKEN Cluster for Pioneering Research in Japan and Durham University in the U.K. They have a new paper out, published in the peer-reviewed journal Science. An introduction to their paper explains:

Most gas in the universe lies in the intergalactic medium [between the galaxies], where it forms into sheets and filaments of the cosmic web. Clusters of galaxies form at the intersection of these filaments, fed by gas pulled along them by gravity. Although this picture is well established by cosmological simulations, it has been difficult to demonstrate observationally.