(Edmonton) The cosmic fireworks that characterize a starburst can abruptly fizzle out after only a relatively brief period of star formation. As a result, far fewer high-mass galaxies are evident, and astronomers want to know why.
A new study shows in unprecedented detail how vigorous star formation can force hydrogen and other gasses high into the surrounding galactic halo, leaving little fuel for the next generation of stars.
The findings were the subject of a recent feature in the journal Nature, with a cover image by Erik Rosolowsky. Originally from Virginia, Rosolowsky recently joined the University of Alberta Department as an assistant professor of astrophysics.
Since 2011, Rosolowsky has been a member of an international collaboration (led by Alberto Bolatto of University of Maryland in College Park) that used the new and powerful Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile to discover billowing columns of cold, dense gas fleeing the disk of nearby starburst galaxy NGC 253, also known as the Silver Dollar Galaxy.
Located 11.5 million light-years away in the constellation Sculptor, this galaxy - with its slightly askew orientation - offers astronomers a rare and fortuitous view of several super star clusters near its center. These clusters denote areas where new stars are forming and they also mark the point of departure for material being ejected from the galaxy.
Rosolowsky worked on mass calculations for this study before creating the 3D animation that helped the team identify the wind movement. "We couldn't see the wind before the new telescope," he said.
ALMA provided enough data for Rosolowsky to build a computer visualization that revealed a phenomenon that was difficult to discern by physical observation. To create the 3D animation, he included data about the distance, brightness and velocity of carbon monoxide molecules in the starburst. ALMA has similar data for other molecules. Further study should help determine how much gaseous material is carried away by stellar winds.
The different colours represent the brightness of the gas at various points. The top of the structure is moving toward Earth, while the bottom part is farther away. The solar wind appears as a yellow, peanut-shaped formation near the top of the structure.
"Part of the complexity is seeing something very faint next to something very bright," Rosolowsky said. "This is the first time we've used this type of visualization for these data. Usually, we use these methods to visualize computer simulations."
Rosolowsky looks forward to using these ALMA data for more work. He will be studying the structure of all the molecular gas seeking to understand how these clouds create the starbursts seen in this and other galaxies.