The Planck space telescope uncovered more than 2,000 galaxy clusters in the process of forming during the first several billion years of our universe. Barely visible in optical telescopes, these systems glow warmly in longer microwave colors visible to Planck. 

In newly published follow-up research, astronomers led by Mari Polletta used the Large Binocular Telescope in Arizona in combination with Hawaii’s Subaru Telescope to study one of these more than 2,000 systems in detail. They also used archival data from Spitzer and Herschel, allowing them to see these systems in the range from microwave to optical and everything in between. Their target was PHz G237.01+42.50 or G237 for short. 

The team identified 63 galaxies in this protocluster, and together these 63 systems and the unresolved galaxies around them seemed to be undergoing 1,000 times the star formation of our own Milky Way galaxy. This is a gobsmacking amount of star formation, and if maintained, it would quickly deplete the system of star-forming materials. According to study coauthor Brenda Frye: Each of the 63 galaxies discovered so far in G237 was like a star factory in overdrive. It’s as if the galaxies were working on overtime to assemble stars. The rate of production was unsustainable. At such a pace, the supply chains are expected to break in the near future, and in a way that permanently shuts down the [protocluster].

Or at least it will shut down unless new fuel is somehow delivered to the cluster. And it looks like the Universe just might be doing that.

Galaxy clusters and protoclusters exist at the junction of the walls and threads of the material that make up the large-scale structure of our universe. Often referred to as the cosmic web, this structure looks a bit like a 3-D web or extremely lacy Swiss cheese. Material can flow through these structures, hollowing out the voids and delivering material to the clusters. Frye goes on to explain: The picture we have pieced together now is that of a successful galaxy protocluster, which is working at high efficiency to assemble galaxies and the stars within them and has an energy supply that is more sustainable.

This is just one set of observations of one protocluster and more work is needed to see if these rates of star formation and methods of funneling in material are the norm. Polletta explains: We are in the process of analyzing more observations on this and other Planck protoclusters with the goal of tracing the gas that gives birth to these newly forming stars and feeds the supermassive black holes, to determine its origin and explain the observed extraordinary activity.

The press release associated with this story goes on to say that the originally planned to launch in the 20-aughts Just Waiting Space Telescope is perfectly designed to observe these systems. Unwilling to count their space telescopes before they have first light, the team is proceeding with their mix of Subaru, Green Bank Telescope, and other ground systems, while looking forward to the scope’s launch hopefully at the end of this year or early in the next.

According to Frye: Protoclusters offer an opportunity to investigate key questions in astronomy that only this new observatory can answer, such as what mechanisms drive the prodigious star formation, and when will the hydrogen supply run out, forcing this galaxy [protocluster] to close its doors and turn into a supercluster similar to the one our Milky Way is in.

I look forward to seeing future papers in this series and understanding more about how our universe has grown into its current state.

More Information

The University of Arizona press release

“Spectroscopic observations of PHz G237.01+42.50: A galaxy protocluster at z = 2.16 in the Cosmos field,” M. Polletta et al., 2021 October 26, Astronomy & Astrophysics