‘Weird’ Galaxy with a Cold-Quasar Center Discovered


NASA's Chandra X-ray Observatory has spotted a strange, distant galaxy cluster about 8 billion light-years from Earth with a cosmic quasar core that is amazingly cold. This particular quasar is called 3C 186, making it the most distant galaxy cluster with a quasar ever seen.

Quasars, among the brightest objects in the universe, form at the central regions of some galaxies, where supermassive black holes feed on matter so furiously that the remaining stuff around them generates tremendous energy transmissions that span the entire electromagnetic spectrum, including radio waves, light and X-rays.

But the heart of the galaxy cluster studied by the Chandra observatory is cold in astronomical terms. with the gas at the cluster's center is a mere 30 million degrees Fahrenheit (16.7 million degrees Celsius), while temperatures at the outskirts tops out around 80 million degrees Fahrenheit (44.4 million Celsius). In quasar physics, "it's positively chilly," researchers said. The extreme drop in temperature occurs because intense X-ray emission from the gas nearer the core cools it down, the researchers added.

Because it took eight billion years for the cluster's light to reach Chandra's instruments, researchers are seeing it as it appeared when the universe was still relatively young — less than half its current age of about 13.7 billion years.

Previous observations have revealed large numbers of clusters with strong cooling cores closer to Earth, less than about six billion light-years. But they appear to be more rare the farther away researchers look. One reason for this may be that more distant galaxy clusters — which are younger, since astronomers are seeing them at an earlier point in the universe's history — merge more often with other clusters or galaxies, researchers said.

This cluster was found fortuitously via a relatively modest Chandra survey. So it's possible that many other similar objects exist at large distances, researchers said.

The image of the cluster surrounding quasar 3C 186 is a composite. It includes a new image from Chandra showing X-ray emissions from gas surrounding the point-like quasar near the center. Optical data from the Gemini telescope in Chile contribute views of nearby stars and galaxies.

Casey Kazan via Astrophysical Journal.


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