Black holes' diet of cold, 'clumpy' clouds regulates star formation

  • Jun 9, 2016
  • Faculty & Staff, Research, Physics & Astronomy

An artist's rendering of cool gas clouds raining into a black hole

An artist's rendering of cool gas clouds raining into a black hole located within a galaxy cluster known as Abell 2597. Image credit: NRAO/AUI/NSF/Dana Berry/SkyWorks/ALMA/ESO/NAOJ.

For the first time ever, astronomers are watching a black hole, located in the center of a galaxy cluster 1 billion light years from Earth, prepare to feast on billowy clouds of cold, clumpy gas.

The observations by the international team of researchers, including two from Michigan State University, provide more evidence that these clouds, which astronomers call galactic “rain,” are responsible for feeding the black hole and regulating the formation of stars.

The work is detailed in the journal Nature.

Obviously it’s not in the form of rain as we know it, but rather a mist of cool gas clouds made mostly of hydrogen molecules, said Mark Voit, an MSU professor of physics and astronomy in the College of Natural Science and a member of the research team.

When conditions are right, these cool gas clouds help make stars. However, some of the clouds fall into the massive black hole that resides at the center of a galaxy cluster. That triggers the production of powerful jets that reheat the surrounding gas like a blowtorch, prevent more cool clouds from forming and limit the number of stars that can form.

The gas clouds the team has discovered are traveling at speeds of almost 800,000 miles per hour toward the black hole.

“One of the fundamental questions in astronomy is what regulates the growth of galaxies,” Voit said. “We now have more evidence that this ‘rain’ slows down star formation in galaxies by feeding the huge black holes at their centers.”

Voit said it was especially gratifying that MSU-led research contributed to this latest discovery. Last year Voit was the lead author of a paper, also published in Nature, that outlined how a “rain” of clouds could regulate star formation in giant galaxies.

“We now have, in fact, seen some of this ‘rain’ going right toward the black hole, as called for by our model,” he said.

The researchers made this latest discovery using the Chile-based Atacama Large Millimeter/submillimeter Array, or ALMA, one of the most-powerful telescopes in the world.

The team focused ALMA’s telescopes 1 billion light years away, on the central galaxy in a cluster known as Abell 2597. The galaxy they studied, which spans some tens of thousands of light years across, is among the brightest in the universe, as it is likely producing many new stars.

Astronomers from a number of institutions contributed to this research, including Megan Donahue, also an MSU professor of physics and astronomy.

Leading the research was Grant Tremblay of the Yale University Center for Astronomy and Astrophysics.

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