'How can all of this be happening?': Scientists spot massive group of ancient galaxies so hot they shouldn't exist

Artist's impression of a forming galaxy cluster in the early Universe: radio jets from active galaxies are embedded in a hot intracluster atmosphere (red), illustrating a large thermal reservoir of gas in the nascent cluster.

Astronomers have spotted an unexpectedly hot galaxy cluster in the early universe that's challenging theories of galactic evolution.

The scorching cluster existed just 1.4 billion years after the Big Bang, blazing far earlier and hotter than current models of galaxy cluster formation predict should be possible. The discovery suggests that the predicted patterns of cluster growth might need a rethink, researchers reported Jan. 5 in the journal Nature.