Newly Discovered Galaxy Cluster Is 8.4 Billion Light Years Away And Unexpectedly Calm

NASA Chandra X-ray telescope captured a view of distant galaxy cluster SPT-CL J2215-3537 (aka SPT2215).  Credit; NASA/CXC/A. Hobart

Transcript

00:00Visit Chandra's beautiful universe.

00:05SPTCL J2215-3537

00:11Astronomers have discovered the most distant galaxy cluster

00:15with an important quality, paving the way to learning how and when

00:19some of these gigantic structures form, and why the universe looks like it does in the present day.

00:25To find this distant and unusually young galaxy cluster,

00:29teams of scientists used NASA's Chandra X-ray Observatory,

00:33along with NASA's Spitzer Space Telescope, the South Pole Telescope,

00:37and the Dark Energy Survey Project in Chile.

00:41The cluster's important quality is that it is relaxed,

00:45meaning that it is not being disrupted by violent collisions with other clusters of galaxies.

00:51This galaxy cluster, called SPTCL J2215-3537,

00:58or SPT-2215 for short, is about 8.4 billion light-years from Earth.

01:05This means our telescopes see it when the universe is only 5.3 billion years old,

01:10compared to its current age of 13.8 billion years.

01:15Galaxy clusters are enormous structures filled with individual galaxies,

01:20huge amounts of hot gas, and dark matter.

01:24In the case of SPT-2215, researchers estimate that it has a mass

01:29some 700 trillion times that of the Sun.

01:33Scientists think that galaxy clusters usually grow by merging with other clusters

01:38and smaller groups of galaxies over billions of years.

01:42This would have been especially true when the universe was younger.

01:46It was, therefore, surprising to find SPT-2215 at its large distance from Earth.

01:52In other words, this discovery suggests that SPT-2215

01:58has become relaxed earlier than expected for a typical galaxy cluster.

02:03Another interesting aspect of SPT-2215

02:08is the evidence for large amounts of star formation happening in its center.

02:13SPT-2215 has a very large galaxy in its middle,

02:18which in turn has a supermassive black hole at its core.

02:22The prodigious amount of star formation shows scientists

02:26that much of the hot gas has cooled to the point where new stars can form

02:30without outbursts driven by the black hole providing a heating source

02:34that prevents most of this cooling.

02:36This addresses an ongoing question of how much black holes stymie

02:40or support the birth of stars in their environments.

02:44Relaxed clusters like SPT-2215 are one of the signposts

02:49that have been used to measure the expansion of the universe.

02:52Adding distant objects like this to the sample of relaxed clusters

02:56allows astronomers to better constrain the acceleration of the cosmic expansion

03:01and the properties of the dark energy that drives it.

03:14NASA Jet Propulsion Laboratory, California Institute of Technology