Cosmic Winds Impact Galaxy Evolution by Blasting Gas

How do cosmic winds impact galaxy evolution? Scientists may now have a clearer picture as to how it happens. Researchers have taken a closer look at these powerful winds that sometimes blow through galaxies to get a better understanding of how galaxies form.

Cosmic wind can easily push low-density clouds of interstellar gas and dust, but not high-density clouds. As the wind blows, denser gas lumps start to separate from the surrounding lower density gas which gets blown downstream. However, high and low-density lumps are partially bound together.

In order to better understand this process, the researchers looked at the way the cosmic wind erodes gas and dust at the leading edge of a galaxy. The wind, or ram pressure, is caused by the galaxy's orbital motion through hot gas in a cluster. In this case, the scientists found a series of intricate dust formations on the disk's edge as cosmic wind worked its way through the galaxy.

"On the leading side of the galaxy, all the gas and dust appears to be piled up in one long ridge, or dust front," said Jeffrey Kenney, one of the researchers, in a news release. "But you see remarkable, fine scale structure in the dust front. There are head-tail filaments protruding from the dust front. We think these are caused by dense gas clouds becoming separated from lower density gas."

Dust filaments that the researchers saw looked a bit like taffy being stretched out. This actually reveals decoupling for the first time.

"A great deal of galaxy evolution is driven by interactions," said Kenney. "Galaxies are shaped by collisions and mergers, as well as this sweeping of their gas from cosmic winds. I'm interesting in all of these processes."

The findings are published in The Astronomical Journal.

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