NASA identifies impact of cosmic chaos on stars' birth

Washington, Oct 28: The phenomenon that causes a bumpy airplane ride, turbulence, may give us a solution to a long-standing mystery about stars' birth, or the absence of it, says a study that uses data from NASA's Chandra X-ray Observatory.

Galaxy clusters are the largest objects in the universe, held together by gravity and they contain tens of thousands of individual galaxies immersed in gas with temperatures of millions of degrees.

The evidence for turbulence comes from Chandra data on two enormous galaxy clusters named Perseus and Virgo.

By analysing observation data of each cluster, the team was able to measure fluctuations in the density of the gas and this allowed them to estimate the amount of turbulence in the gas.

"Our work gives us an estimate of how much turbulence is generated in these clusters," said Alexander Schekochihin of University of Oxford.

These results support the "feedback" model involving super massive black holes in the centers of galaxy clusters.

"We knew that somehow the gas in clusters is being heated to prevent it cooling and forming stars. The question was exactly how," said Irina Zhuravleva of Stanford University in Palo Alto, California, who led the study.

Previous studies show super massive black holes pump vast quantities of energy around them in powerful jets of energetic particles that create cavities in the hot gas.

Zhuravleva and her colleagues have now provided new insight into how energy can be transferred from these cavities to the surrounding gas.

The interaction of the cavities with the gas may be generating turbulence, or chaotic motion, which then disperses to keep the gas hot for billions of years, suggested the study.

While a merger between two galaxy clusters may also produce turbulence, the outbursts from super massive black holes are the main source of this cosmic commotion in the dense centres of many clusters, concluded researchers.

The study appeared in the journal Nature.

IANS