February 4, 1999
Vol. 18 No. 9

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    [john carlstrom], by jason smith  John Carlstrom, Associate Director of the Center for Astrophysical Research in Antarctica and Professor in Astronomy & Astrophysics

    Carlstrom’s research gets $1 million boost

    By Steve Koppes
    News Office

    John Carlstrom’s quest to solve some of the biggest questions regarding the origin and evolution of the universe has just received a $1 million boost from the James McDonnell Foundation of St. Louis.

    Carlstrom, Associate Director of the University’s Center for Astrophysical Research in Antarctica and Professor in Astronomy & Astrophysics, was one of 10 McDonnell Centennial Fellows named by the McDonnell Foundation Jan. 26. The fellowships target scientist-scholars whose work will contribute substantially to the development of knowledge and its responsible application in the next century.

    “John Carlstrom is a brilliant experimentalist and observer,” said Sir Martin Rees of Cambridge University. “It is excellent news that the McDonnell Foundation has recognized his distinguished record and the fundamental importance of his forthcoming projects for cosmology.

    “His example shows that, even in a field that is normally envisaged as ‘big science,’ an innovative individual can make a real impact; the McDonnell Foundation has selected a scientist for whom the award can make a crucial difference,” Rees said.

    The McDonnell Fellowship is the second major award for Carlstrom in seven months. Last June, he was named one of 29 MacArthur Fellows by the John D. and Catherine T. MacArthur Foundation of Chicago. The MacArthur Fellowship brought Carlstrom $260,000, no strings attached.

    “I used to think Einstein must have had this incredible, wonderful life to think big thoughts and solve big issues,” Carlstrom said. “When I was in graduate school, I was working much more on details––still important research–– but not so much the big picture.”

    But Carlstrom and his fellow astrophysicists have learned a lot about the universe since his student days. Now they have access to technology that becomes more powerful and precise by the day. “This has become a tremen-dously exciting time,” Carlstrom said. “We now know that we can go out and get those big answers. It is a Golden Age for cosmology.”

    Carlstrom would like to use his McDonnell funds to greatly enhance a special imaging system that he and his collaborators have developed to detect the cosmic microwave background radiation, the big bang’s afterglow, as it is distorted by intervening galaxy clusters on the way to Earth. Most people experience this background radiation as snow on their television screens or as the hiss between radio stations, but to astrophysicists it is packed with information about the early universe.

    Carlstrom’s observations of the distorted form of this radiation has enabled him to measure the expansion rate and mass density of the universe. Such data will allow him and his colleagues to determine whether the universe will expand forever, ultimately collapse or remain precisely balanced between the two. A definitive answer requires more extensive measurements.

    Carlstrom’s team has been working with arrays of radio telescopes that were not built for the type of imaging he does. These telescopes do a good job of imaging small objects at high resolution. However, Carlstrom needs a wider field of view and higher sensitivity in order to see his target objects––galaxy clusters.

    The team studies the way galaxy clusters distort the spectrum of the background radiation, much like a stained-glass window distorts optical light. So he and his colleagues built special receivers, which when fitted to the telescopes, make them nearly ideal for the experiment.

    Nevertheless, the going is slow because Carlstrom’s instrument lacks a vital piece of hardware. Plus, his team has use of the telescopes for only a small part of the year, during the summer when observing conditions are less than ideal.

    “Our receivers are sensitive to a section of the spectrum that’s 10 gigahertz wide, and yet the electronics at the telescope arrays can only handle about a tenth of that,” Carlstrom said. “Most of the signal we actually receive we have to just throw away. It’s never recorded, never analyzed, because we don’t have the hardware to do that.”

    Images that used to take 10 days to make would require less than half a day using new electronics that take advantage of expanded bandwidth. Combined with year-round access to a new array of telescopes, Carlstrom’s team could map large portions of the sky rather than just selected targets. Carlstrom plans to use the McDonnell award to help build the new array and electronics.

    “We can find things now as far back as something like half the age of the universe. If we could just go blindly and find everything that is out there, inventory the distant universe, we should be able to go much farther back,” Carlstrom said. “I think that is just tremendously exciting. Thanks to the McDonnell award it’s not just a wish. I think we’ll make that happen.”

    The results from the new array would nicely complement another experiment being built by Carlstrom and his colleagues at Chicago and Caltech that will begin in early 2000 at the South Pole. Using the Degree Angular Scale Interferometer or DASI, an array of telescopes in one compact structure, the team will precisely measure minute temperature variations in the cosmic microwave background itself.

    These variations will reflect a state of the universe when it was only 300,000 years old––beyond the epoch when galaxies were formed, beyond the formation of the first stars, to a time when electrons and protons were combining to form hydrogen, Carlstrom said.

    The DASI will provide researchers with a direct snapshot of the seeds that formed all structure in the universe, including galaxies and great walls of galaxies. The two new instruments will allow them to explore the structure of the universe shortly after its birth to its present age of approximately 15 billion years.

    Carlstrom, 41, joined the Chicago faculty in December 1995. He received his bachelor’s degree in physics from Vassar College in 1981 and his doctoral degree in physics from the University of California, Berkeley, in 1988. He was a member of the astronomy fa-culty at Caltech from 1991 to 1995.

    The McDonnell awards mark the 100th anniversary of the birth of James McDonnell, founder of the company that became McDonnell Douglas Corporation. He established the McDonnell Foundation in 1950.