Cosmic Wonder

Astrophysicist Seeks Answers 

By Angus McClellan '05

Michael Rutkowski

On the southern shore of the Rappahannock River lies the small and secluded town of Urbanna, Virginia, whose distance from major cities isolates it from the excessive light that often overwhelms the stars of the night sky. It is the childhood home of Dr. Michael Rutkowski '07, a post-doctoral astrophysicist currently working at the University of Minnesota, and it was these geographical and heavenly conditions that first introduced him to the wonders of the universe.

On a cold January evening in 1997, Rutkowski's father loaded his family into an old Datsun pickup truck and drove to the cornfields outside of town. In the night sky was a sight that no one had seen since the reign of the Egyptian pharaoh Pepi I in 2300 B.C. Splashed across the celestial sphere was the Hale-Bopp Comet and its 30-million-mile-long tail, a fiery display that sent Rutkowski and crowds of other curious onlookers into the fields for months of spectacle before its orbit sent it back to the outer solar system. The comet is scheduled to re-enter our solar system sometime around the year 4385 A.D.

That comet and nightly views of The Milky Way galaxy made it easier for Rutkowski to discover astronomy. It was all right there above his head. In high school he developed a passion for math and physics, and by his junior year he knew he wanted to acquire a solid foundation in those sciences.

"I started looking at schools that had strong physics programs. I looked at big and small colleges. In my applications I was simply writing, ‘I would like to be a physicist at your university.' I knew what I wanted. And my parents were quite clear. They said, ‘You can go to any college you want, but we can't pay for any of it.'"

Road to the Telescope 

He applied to the University of Virginia, Princeton, and Hampden-Sydney. Despite its small size, Hampden-Sydney had four or five physics professors, providing a comparatively strong student-to-faculty ratio. He also was among those who had earned a Venable Scholarship and other funding, which eventually paid for the majority of his tuition and other expenses.

"At Hampden-Sydney, they brought me to campus and showed me this place ... and it just fit into my idea of what a college should be," he said. "It was an island unto itself. It was where learning happened. That was the reason you were there. You didn't have to worry about life outside of the walls. That's what I thought, and I still believe that."

He was soon immersed in the culture and teachings of Hampden-Sydney. "Basic physics is pretty much the same wherever you go," he said, so he knew he was looking for more than just a stack of information to memorize. He accepted the College's role in forming him into a good man and a good citizen. He took rhetoric, political science courses, and economics to satisfy his core curriculum requirements. He learned how to communicate effectively. He learned how to argue. He also took Greek and joined the Society of '91. It all helped him to become a better man and a better astronomer.

"I can't tell you how many times I've looked at a word and had no idea what it meant, but I knew the Greek root, and so I had at least some idea," he said. "And even though many of the Greeks' [scientific] ideas were wrong, the point in my classes was not necessarily to learn what the Greeks learned. The point of education is not simply to learn how to record knowledge that someone else gives you. The point of education is to learn how to think."

"I believe liberal arts colleges are designed to teach people how to think about the universe," he said. "That's not how to do something in the universe, not how to operate this particular telescope or do this experiment. The idea is to teach students how to think about astronomy, to provide as many tools as possible to establish a foundation for future work." Graduating summa cum laude in both math and physics, Rutkowski was soon ready to put his critical thinking and mathematical tools to good use.

"So undergrad is about thinking," he said. "But graduate school is about doing."

Eyes in the Sky

There are few fields as open and unexplored as astrophysics. According to the Bureau of Labor statistics, for every astronomer and physicist in the country, there are about 32 lawyers. And the vastness of the universe itself provides a seemingly infinite number of opportunities for discovery. By using both ground-based and space-based telescopes, Rutkowski has been able to employ techniques for understanding stars and galaxies that would have astounded astronomers just a few decades ago.

Michael RutkowskiRutkowski was able to examine data from the Hubble Space Telescope's latest WFC3 camera, which can observe a broader portion of the electromagnetic spectrum compared with the previous cameras. This spectrum is a scale of all possible frequencies of electromagnetic radiation, from shorter wavelengths of gamma rays and ultraviolet rays, through the visible spectrum of blue to red, out to longer wavelengths of radio and beyond. The HST operates from ultraviolet to near-infrared.

His dissertation "was focused on ultraviolet radiation from early-type galaxies. Those are a general class of galaxies that are assumed to have formed when the universe was very, very young. They formed most of their stars all at once and have been passively evolving ever since, essentially producing no new stars," he said.

Rutkowski looked at the intensity of electromagnetic radiation coming from stars in these old galaxies. When gas first coalesces to form a star, the intensity of its electromagnetic radiation rapidly increases, peaks, and then decreases as the star ages. So initially the star becomes bluer, or "ultraviolet," to a certain point, and then it begins to emit radiation of longer, redder wavelengths as it gets older. Also, as the galaxy ages, hot, blue stars die sooner leaving only cooler, redder, longer-living stars behind. So the spectra of the galaxies shift over time from the blue to the red. By measuring the intensity of light from galaxies of different wavelengths, astronomers can better determine how old those galaxies are.

"But we found young stars in old galaxies," he said. "And young stars need new gas. Since these were old galaxies, and since we believe that new galaxies use up their gas early to make stars, where was this new gas coming from? We believed, as others have, that small clumps of gas-these dwarf galaxies that are pretty minor-were falling in to these larger galaxies, bringing in fresh supplies of gas. So then there was a burst of new stars for about a couple 100 million years. We were trying to answer the question, ‘Where is the blue light in these old galaxies coming from?' It was all telling us about the evolution of galaxies."

Rutkowski is still looking at ultraviolet radiation in his current post-doctoral research at the University of Minnesota. He's basically trying to figure out how hydrogen atoms have been ionized, or stripped of their single electrons, throughout the intergalactic medium (the nearly particle-free space between galaxies). Ultraviolet radiation from early stars accounts for some of the ionized hydrogen atoms throughout the universe, but it's unclear what else has contributed to the ionization.

"We know there are other sources of ionizing radiation in the local universe-such as quasars, the massive black holes that sit in the centers of galaxies, consuming material and spewing out radiation in huge, powerful jets. Those produce enough of these photons to ionize the universe locally. But what about in high redshift galaxies, where we don't find quasars at the numbers we do locally? What is producing this radiation? So right now, I'm looking for escaping ionizing photons in the local universe to give us some insight to the source of early ionization. If it's not star-forming galaxies or the piddling progenitors of the quasars we observe in the local universe, then it must be something more exotic.

"And having to appeal to more exotic, unobserved phenomena to explain nature is one of the most unappealing propositions to scientists. We appreciate simple explanations. If it quacks like a duck, then it's probably not a Volkswagen Beetle."

Rutkowski describes astronomy as a "gateway science. It's intrinsically exciting to kids. When you're six years old, and someone tries to describe for you the size of the solar system or galaxy, the enormity of it all can be thrilling to consider, and that ‘wow' factor is the key to engaging that kid's mind. In the same way, a college student who says, ‘I think I want to do something in science,' if he wants to contribute to our understanding of the universe, Astronomy 101 is a gentle introduction."

Dark Side of the Galaxy

But the wonders of the universe don't stop at the end of undergraduate school. Rutkowski still ponders at least one, big question: "‘What is dark energy? What is dark matter?'" he asks. "Only about five percent of the universe is in the form of ‘normal matter'-stuff that you and I are familiar with: hydrogen, stars, gold, apple pie, galaxies-that's only five percent of the stuff that requires the universe to have the shape that it has.

"It seems that about 20 percent of the universe is ‘dark matter.' It interacts gravitationally-it is matter, it has mass, but it doesn't seem to interact electromagnetically. It doesn't produce light. It doesn't absorb light. It doesn't reflect light. It doesn't do anything electromagnetically. It doesn't seem to work in that way. But we know it exists because when we count up all of the stars and measure how fast they're zipping around the centers of the spiral galaxies, the gravitational potential they feel is much stronger than it would be if the only mass was in the stars. And we know it's not dust, planets, or very faint stars. There's some other mass there.

Michael Rutkowski

"But that's still only 25 percent of the energy density of the universe. There's still another 75 percent, which we call ‘dark energy.' And the exciting thing about this is we have no clue what it is. We have no idea. That's the big discovery I want to see in my lifetime.

"The existence of dark energy is probably telling us that somehow our physics is incomplete. What makes it so exciting is that once we figure out what it is, it will fundamentally change our understanding of physics. We understand the quantum world, and we understand the macroscopic world, but we haven't put it all together. There's a disconnect. Dark energy will probably give us insight into that solution. It will be a revolution unseen since Einstein and his theory of relativity."

Liberal Arts and Astronomy

It may seem unusual that an astrophysicist would pursue his undergraduate degree at a liberal arts college. But science and the liberal arts often go hand-in-hand. Part of that liberal arts education is sharpening and freeing the mind to explore our world, as well as understanding our place in it: including on the physical and cosmic levels.

Indeed, any field that requires effective communication, clarity of thought, rational thought, foresight, and the ability to manage complex systems is better understood with a mind tuned in the liberal arts. As Physics and Astronomy Professor Dr. Hugh "Trey" Thurman III said, "Just as one can reason, argue, and communicate with words and speech, he can do the same with numbers, formulas, and graphs."

Image courtesy of Digitalblasphemy