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

Space.com

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

Transcript

00:00 Visit Chandra's beautiful universe.

00:04 SPTCL J2215-3537

00:10 Astronomers have discovered the most distant galaxy cluster

00:14 with an important quality, paving the way to learning how and when

00:18 some of these gigantic structures form, and why the universe

00:22 looks like it does in the present day. To find this distant

00:26 and unusually young galaxy cluster, teams of scientists used

00:30 NASA's Chandra X-ray Observatory, along with NASA's Spitzer Space Telescope,

00:34 the South Pole Telescope, and the

00:38 Dark Energy Survey Project in Chile. The cluster's

00:42 important quality is that it is relaxed, meaning that it is not being

00:46 disrupted by violent collisions with other clusters of galaxies.

00:50 This galaxy cluster, called SPTCL

00:54 J2215-3537,

00:58 or SPT-2215 for short, is

01:02 about 8.4 billion light years from Earth. This means

01:06 our telescopes see it when the universe is only 5.3 billion years old,

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

01:14 Galaxy clusters are enormous structures

01:18 filled with individual galaxies, huge amounts of hot gas,

01:22 and dark matter. In the case of SPT-2215,

01:26 researchers estimate that it has a mass some 700

01:30 trillion times that of the Sun. Scientists think

01:34 that galaxy clusters usually grow by merging with other clusters

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

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

01:46 It was, therefore, surprising to find SPT-2215

01:50 at its large distance from Earth. In other words,

01:54 this discovery suggests that SPT-2215

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

02:02 Another interesting aspect

02:06 of SPT-2215 is the evidence for large amounts

02:10 of star formation happening in its center.

02:14 SPT-2215 has a very large galaxy in its middle,

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

02:22 The prodigious amount of star formation shows scientists that much of the

02:26 hot gas has cooled to the point where new stars can form without

02:30 outbursts driven by the black hole providing a heating source that prevents

02:34 most of this cooling. This addresses an ongoing question

02:38 of how much black holes stymie or support the birth of stars in their environments.

02:42 Relaxed clusters like SPT-2215

02:46 are one of the signposts that have been used to measure

02:50 the expansion of the universe. Adding distant objects like this

02:54 to the sample of relaxed clusters allows astronomers

02:58 to better constrain the acceleration of the cosmic expansion and the properties

03:02 of the dark energy that drives it.

03:06 [music]

03:10 [music]

03:14 (gentle music)

03:16 (electronic music)

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