Tour: Black Hole Fails to Do Its Job

Astronomers have discovered what can happen when a giant black hole does not intervene in the life of a galaxy cluster. Using NASA's Chandra X-ray Observatory and other telescopes they have shown that passive black hole behavior may explain a remarkable torrent of star formation occurring in a distant cluster of galaxies.

Galaxy clusters contain hundreds or thousands of galaxies pervaded by hot, X-ray emitting gas that outweighs the combined mass of all the galaxies. Ejections of material powered by a supermassive black hole in the cluster's central galaxy usually prevent this hot gas from cooling to form vast numbers of stars. This heating allows supermassive black holes to influence or control the activity and evolution of their host cluster.

But what happens if that black hole stops being active? The galaxy cluster known as SpARCS1049, located 9.9 billion light years away from Earth, is supplying one answer.

Based on observations from NASA's Hubble Space Telescope and Spitzer Space Telescope, astronomers had previously discovered stars were forming at an extraordinary rate of about 900 new Suns worth of mass per year in SpARCS1049. This is over 300 times faster than the rate at which our galaxy, the Milky Way, is forming its stars.

What's going on? It appears that the supermassive black hole at the center of SpARCS1049 has had its fuel supply choked off. The Chandra data show that the temperature of the gas at the site of the prodigious star formation has cooled to about 10 million degrees. This is in contrast to most of the rest of the cluster where the gas is hotter at about 65 million degrees.

The highest concentration of this relatively cool gas is not in the center of the cluster — it's about 80,000 light years away and matches the location of the fastest star formation. This means there is essentially no fuel for the black hole to pull toward it, rendering it dormant. Without energy pumping out of the black hole, the gas can cool enough to unleash a deluge of new stellar birth. This behavior differs greatly from nearer and younger galaxy clusters that typically show black holes stifling high levels of star formation.