Light from quasars provides insights into swirling clouds of gas that form galaxies

A new study of light from quasars has provided astronomers with new insights into the swirling clouds of gas that form stars and galaxies, which proves that the clouds can shift and change more quickly than believed.

Led by University of Illinois at Urbana-Champaign astronomy professor Robert J. Brunner and former graduate student Troy Hacker (now with the U.S. Air Force), the team used data from the Sloan Digital Sky Survey.

Brunner said that quasars are merely tools in this study to help them actually find and study what they're really interested in, which is the invisible gas that surrounds galaxies.

He said that the gas gets turned into stars, and stars expel gas back out of the galaxy, asserting that one of the things that they have a hard time understanding is, how is that gas involved in the formation and evolution of a galaxy? So they use quasars as big searchlights.

The novel aspect of Brunner and Hacker's work is that it looks at the quasar light not once, but at two different times.

Astronomers have long assumed that any changes in large structures such as nebulae or galaxies would take eons and would not be observable during a human lifetime. But in the span of only five years, Brunner and Hacker saw measurable shifts in a small but substantial number of the giant gas clouds mapped by the Sloan Survey.

As a possible explanation, the researchers posit that the gas clouds are much smaller than theories point to.

Brunner said that means that it can't be a spherical ball of gas; it's more like the clouds in our atmosphere, adding that the gas around other galaxies has different types of structures and shapes.

The study has been published in the Monthly Notices of the Royal Astronomical Society.