Probing the Grandeur of Galaxies

Grad student’s work grabs international attention

By Karl Hill

Pardon the pun, but Glenn Kacprzak is a star in the world of extragalactic research. When 110 astronomers from around the globe gathered in Shanghai, China, in 2005 to share the latest advances in their specialized field of research – “Probing Galaxies through Quasar Absorption Lines” was the conference title – Kacprzak was among those invited to talk.

Only one other graduate student shared that distinction, said his faculty adviser, Chris Churchill. But the clincher came at the close of the conference.

“At the end of these meetings they typically have an open forum, moderated by a senior researcher, to discuss the coolest stuff from the talks and who presented results that will make us think about new things,” Churchill said. “And Glenn’s work came up.”

Kacprzak’s research on the gigantic halos of gas that surround galaxies has been noticed by those in the know – he also gave talks at astronomy conferences in Crete in 2004 and in San Diego in 2005 and presented a poster at an American Astronomical Society meeting in Seattle earlier this year – in part because his findings have tended to upset previous assumptions about the structure of this galactic gas.

A decade ago, the conventional wisdom held that these halos were “basically spherical and the gas was uniformly distributed,” Kacprzak said. “People thought of them sort of as bubbles, and beyond a certain point there would be no gas.”

Instead, astronomers know now that the gas is structured more like knotty filaments that can span millions of light years, reaching far beyond the presumed spherical halos. Kacprzak’s research has contributed important details to this new understanding. He has found “lumpiness and holes” instead of uniformly distributed gas, for instance, and he has discovered that the more asymmetric a galaxy’s shape is, the more gas it has in its halo. He has learned that the interaction of colliding galaxies may produce more gas, as well as chimneylike disturbances in the gas clouds.

All of which helps astronomers understand how galaxies have formed and evolved over time. Cosmologists develop models that attempt to show how the universe came to be the way it is now. Hard data from observations like Kacprzak’s help constrain and refine the models. And because the techniques he uses make it possible to study galaxies at extreme distances, the observations can reveal conditions as they were billions of years ago, when the universe was about half its current age.

Kacprzak’s research, supported by an NMSU Graduate Research Enhancement Grant, involves the use of quasars, some of the brightest objects in the sky, as tools for analyzing gas halos surrounding galaxies. The quasars shine through the gas like flashlights through fog. By analyzing the interaction of the light and the gas – the absorption signatures – Kacprzak can study the dynamics, chemical content and other aspects of the gas surrounding galaxies that are too far away for the gas to be seen otherwise.

As a boy growing up in the countryside outside of Montreal, Quebec, Canada, Kacprzak was intrigued by the night sky and the grandeur of galaxies. But even then, he recalls, “I was more interested in understanding what was going on and what was out there, as opposed to just admiring the beauty.”

This inquisitiveness led him to obtain a bachelor’s degree in astrophysics at Queen’s University in Kingston, Ontario, and a master’s degree at Saint Mary’s University in Halifax, Nova Scotia, before coming to NMSU for his Ph.D. in astronomy.