June 11, 1998
Vol. 17, No. 18

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    Astrophysicist Carlstrom wins MacArthur award

    John Carlstrom, a University astrophysicist who over the next two years hopes to answer one of astronomy's largest questions, is one of 29 new MacArthur Fellows announced by the John D. and Catherine T. MacArthur Foundation.

    Sometimes known as the MacArthur "genius awards," the fellowships provide unrestricted, "no strings attached" grants that range from $220,000 to $375,000 over five years, depending on the age of the recipient. Carlstrom is the 16th University of Chicago faculty member to receive the award since it was established in 1981.

    Carlstrom is Associate Professor in Astronomy & Astrophysics and Associate Director of the Center for Astrophysical Research in Antarctica. As an experimental astrophysicist, he has already solved several important astronomical problems by developing and building new and highly sensitive instruments. In his latest work, he will over the next year make what may be the most direct measurements ever of the rate of the universe's expansion. This rate is known as the Hubble constant, named for University alumnus Edwin Hubble, whose name also graces the Space Telescope. If Carlstrom and his colleagues succeed, they will use the Hubble constant to directly calculate a completely independent and accurate measure of the age of the universe.

    "I'm really in shock over this," Carlstrom said on learning of the award. "It is truly wonderful and a great opportunity. This is a special grant, so I want to think very hard about the best way to use it to support research -- perhaps rather risky research -- that would not have been possible without it."

    Carlstrom's specialty is studying radiation from space that falls between infrared, or heat, radiation and radio waves. This "millimeter wave" radiation is emitted by disks of gas that are forming new solar systems in space and it is the form of the famous "cosmic microwave background radiation" emitted as a remnant of the Big Bang.

    Carlstrom has advanced studies of both developing solar systems and the microwave background by devising extremely sensitive detectors. By also placing them in precisely arranged arrays, he employs a very sensitive technique called interferometry to measure small differences in the arrival times of the radiation photons, thereby greatly increasing the information they provide. When Carlstrom places these detectors in large radio telescopes, he and his colleagues see a more precise picture of the accretion disks and the cosmic background radiation than ever before.

    Next year, Carlstrom and his colleagues will take 13 of his new detectors to the University's South Pole observatory, which is funded by the National Science Foundation. There, they will mount them on a new telescope they are building to make the most precise measures to date of the subtle variations in the cosmic microwave background, learning more than ever previously known about the way the universe's largest structures of galaxies began to form over 10 billion years ago.

    "We are taking a picture of the origin of the universe," Carlstrom said, "and it will tell us whether the universe will expand forever or collapse of its own gravitational attraction. We will also be able to make a very precise measure of the inflation model, which is the current favorite theory of the universe's origin. I think that's very exciting."

    Carlstrom says his colleagues at the radio telescope arrays have been an enormous help to his work. "They've been phenomenal," he said, citing especially those at the James Clerk Maxwell and Caltech sub-millimeter telescopes in Hawaii, and the Caltech Owens Valley and the BIMA telescope arrays in California. "By having access to these multimillion-dollar telescopes, we are enormously leveraged," he said. "We could not do this work without their help."

    Carlstrom co-designed and built the first interferometer operating at sub-millimeter wavelengths, and the first millimeter-wavelength interferometric imaging polarimeter, which enables astrophysicists to investigate the role of magnetism in star formation.

    Carlstrom received his B.A. in 1981 from Vassar College and his Ph.D. in 1988 from the University of California, Berkeley. He is 41 years old.

    Individuals cannot apply for MacArthur Fellowships. They are chosen each year from nominations by 100 or more nominators who are selected for expertise in their respective fields and their ability to identify exceptional creativity.

    The John D. and Catherine T. MacArthur Foundation is a private, independent grant-making institution dedicated to helping groups and individuals foster lasting improvement in the human condition. The foundation seeks the development of healthy individuals and effective communities; peace within and among nations; responsible choices about human reproduction; and a global ecosystem capable of supporting healthy human societies.