Astrophysicists Announce Superwinds Discovery

Although most people think of space as empty, it does, in fact, contain highly dilute gases. These gases, moving at incredible speeds, constitute the superwinds. They can span distances equal to about 1 percent of the size of the observable universe.

New evidence suggests that the winds follow the long axes of what astrophysicists call superclusters, say University of Kansas astrophysicists Adrian Melott and Dmitri Novikov.

Superclusters are the largest known building blocks of the universe. They are made up of smaller clusters of thousands of galaxies separated by long stretches of nearly empty space.

Melott, speaking on behalf of a team of seven researchers, today told a press conference at the American Astronomical Society annual meeting in Austin, Texas, that "this is our first detection of exactly the kinds of winds we think should accompany the flow of matter along the axes of superclusters.

"It looks like we are beginning to develop a good understanding of the formation of structure in the universe."

In the April 17, 1998, issue of the journal Science, Jack Burns, professor of physics and astronomy at the University of Missouri, who also was involved in the research presented today, published his argument that as gas, stars and galaxies fall together into smaller clusters, the merger gives rise to local winds.

These local winds bend the jets of gas that stream out in opposite directions from the cores of some galaxies.

The jets -- thought to originate from giant black holes -- are sometimes bent into "U" or "V" shapes, Melott said. The jets usually don't exceed a million light years in length. The new research shows that the local winds blowing inside the clusters and bending the jets are, like the superwinds, oriented along the long axes of superclusters.

The research team believes that the superwinds feed matter into galactic clusters, Melott said, and determine the direction of the local winds in much the same way as a breeze on Earth determines the direction of smoke that rises from a chimney.

Melott said the team's discovery was based on an analysis of the direction of local winds that distort jets of gas in 12 different galactic clusters.

The team compared the local wind directions within the clusters with the alignment of other nearby galaxy clusters. They found that the nearby clusters were aligned with the flow of the wind inside the central cluster.

The odds that mere chance is responsible for that alignment are only about one in 50, Melott said, leaving the door open for the superwind explanation.

In addition to data taken from the National Science Foundation's Very Large Array (a VLA radio telescope setup was shown in the recent movie "Contact") the group relied on information from other astronomers about distances to a variety of galactic clusters.

Melott said that University of Maine astronomers David Batuski and Chris Miller, using the Steward Observatory at the University of Arizona, ascertained previously undetermined distances to a number of the clusters.

Two KU undergraduates, Michael Kaufman, senior from McPherson, and Brian Wilhite, since graduated and from Olathe, also contributed to the research, Melott said.

Melott, commenting on the significance of the work, said, "We've had no evidence until now of the particular kinds of flows that bring about the structures we're looking at."

The findings announced today will be published in Monthly Notices of the Royal Astronomical Society, a British journal.