How a Galactic Metropolis is Constructed: Secrets of the Spiderweb Galaxy

Galaxy clusters are some of the largest objects in the universe. Yet their formation isn't well understood. Now, scientists have used ESO and other telescopes in order to better understand the formation of one particular cluster: the Spiderweb Galaxy and its surroundings.

In order to learn more about this galaxy, the researchers used the LABOCA camera on the APEX telescope in Chile to make 40 hours of observations of the Spiderweb Cluster at millimeter wavelengths. This revealed that there were about four times as many sources detected in the area of the Spiderweb compared to the surrounding sky. By comparing the new data with complementary observations, the scientists confirmed that many of these sources were at the same distance as the galaxy cluster and must be parts of the forming cluster.

"This is one of the deepest observations ever made with APEX and pushes the technology to its limits-as well as the endurance of the staff working at the high-altitude APEX site, 5050 meters above sea level," said Carlos De Breuck, co-author of the new study, in a news release.

That's not all the researchers found, either. When they looked at where the newly detected star formation was taking place, they found it concentrated mostly in a single region, as opposed to it taking place is large filaments connecting galaxies.

"The new APEX observations add the final piece needed to create a complete census of all inhabitants of this mega star city," said Helmut Dannerbauer, one of the researchers. "These galaxies are in the process of formation so, rather like a construction site on Earth, they are very dusty. We aimed to find the hidden star formation in the Spiderweb cluster-and succeeded-but we unearthed a new mystery in the process; it was not where we expected! The mega city is developing asymmetrically."

The findings are published in the journal Astronomy & Astrophysics.