People have always wondered where we, our Earth, our galaxy, come from. A group of scientist has now driven that quest one step further and taken a peak at how the stars that gave rise to most of the material found on our universe formed over cosmic history.
University of Miami professor of physics in the College of Arts and Sciences, Joshua Gundersen is part of an international research team that built an innovative new telescope called BLAST (Balloon-borne Large-Aperture Sub-millimeter Telescope) and launched it to the edge of the atmosphere, where it discovered previously unidentified dust-obscured, star-forming galaxies that could help illuminate the origins of the universe.
"BLAST has given us a unique picture into the development of other galaxies and the earliest stages of star formation of our own Milky Way," Gundersen explains. "The light we're getting from these submillimeter galaxies is from a time when they were first forming. In a sense, it's like getting a baby picture."
The data analyzed over the past two years reveals close to a thousand of these "starburst" galaxies that lie five to ten billion light years from Earth, produce stars at an incredible rate, and hide about half of the starlight in the cosmos. The findings were recently published in the journal Nature.
Until BLAST came along, most of the galaxies in the universe have been detected at optical wavelengths visible to the naked eye. The "starburst" galaxies identified by Gundersen and his colleagues however are a new class of galaxies, enshrouded by dust that absorbs most of their starlight and then re-emits it at far-infrared wavelengths.
During an 11-day flight in 2006, the telescope, while tethered to a balloon 120,000 feet above Antarctica, took measurements in three different submillimeter wavelengths that are nearly impossible to observe from the ground. "By going to balloon altitudes, we got a nice, crystal-clear picture of these things," Gundersen said. "It is these far-infrared and submillimeter wavelengths that we're able to detect with BLAST," Gundersen explains.
Graduate student Nick Thomas spent seven weeks at the McMurdo scientific research station in Antarctica, where he helped assemble the device and worked on some of its electronic systems.
"Having worked in a project of this magnitude and in the company of a superb group of scientists has been one of the highlights of my career thus far," said Thomas. "Collaborating on this project has been an incredible learning experience both at the personal and the professional level."
The data from BLAST is being combined with information from other NASA observatories like the Spitzer Space Telescope and the Chandra X-ray Observatory, helping astronomers and cosmologists to better understand the evolutionary history of these "starburst" galaxies and how they may be associated with larger-scale structures in the universe.
The work on BLAST has helped pave the wave for one of the European Space Agency's most ambitious missions to study the cosmos: The Herschel telescope, which launched into orbit earlier this month from a space center in French Guiana. Herschel will peer into the dustiest and earliest stages of planet, star, and galaxy growth, using the same detector system that flew aboard BLAST.
"The idea with BLAST was that we could test a new detector system on a much cheaper, faster platform, namely a balloon payload," Gundersen says. "Herschel has an identical detector system to BLAST, along with other important instruments. "It will do a lot more than BLAST did, but we achieved some of the important goals first."
- Peter A. R. Ade, Itziar Aretxaga, James J. Bock, Edward L. Chapin, Matthew Griffin, Joshua O. Gundersen, Mark Halpern, Peter C. Hargrave, David H. Hughes, Jeff Klein, et al. Over half of the far-infrared background light comes from galaxies at z ≥ 1.2. Nature, 2009; 458 (7239): 737 DOI: 10.1038/nature07918
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