Iowa State researchers contribute to discovery of gamma rays from starburst galaxyNovember 03, 2009AMES, Iowa - Iowa State University astrophysicists contributed to the recent discovery that a galaxy quickly creating new stars is also a source of high energy gamma rays. The discovery has just been published by the journal Nature. The study reports that researchers using the VERITAS array of four telescopes at the Fred Lawrence Whipple Observatory in Arizona have detected gamma rays of a trillion electron volts coming from the M 82 galaxy. The corresponding author of the article is Wystan Benbow of the Harvard-Smithsonian Center for Astrophysics and the Whipple Observatory. Researchers discovered cosmic rays (mostly hydrogen nuclei) from space nearly a century ago and have developed theories about their origins in supernova remnants and star-forming galaxies, but hadn't found evidence to support those theories. "This is a step toward solving a 100-year-old puzzle in cosmic ray physics," said Frank Krennrich, an Iowa State professor of physics and astronomy and a collaborator on the VERITAS project. Gamma rays are high energy electromagnetic radiation. The rays discovered by the VERITAS researchers have a trillion times the energy of visible light. M 82 is a galaxy in the direction of the Ursa Major constellation that's 12 million light years from Earth. It is classified as a starburst galaxy. Such galaxies are colliding with other galaxies, causing shockwaves that compress gases and create stars at very high rates. "What this shows is that there is a strong connection between a galaxy with high star formation, high gas density and the production of cosmic rays," Krennrich said. But Krennrich said there's more work to be done to definitively trace gamma rays to cosmic rays in starburst galaxies. Researchers believe more knowledge of gamma rays could help them explore distant regions of space, help them look for evidence of dark matter, determine how much electromagnetic radiation the universe has produced and answer questions about the formation of stars and galaxies. Krennrich said one key to current gamma ray research is the VERITAS telescope system (that's the Very Energetic Radiation Imaging Telescope Array System). The $20 million instrument started operating in 2007 and is the world's most sensitive instrument for detecting gamma rays. It's not easy to detect those rays. Even with their high energies, gamma rays can't penetrate the earth's atmosphere. When they hit the atmosphere, they create showers of electrons and positrons that create a blue light known as Cerenkov radiation. Those showers move very fast. And they're not very bright. VERITAS looks for the rays with four reflector disks 12 meters across that look like satellite dishes. The reflectors are covered with mirrors that direct light into cameras attached to the front of each disk. Each camera is about 7 feet across and contains about 500 tube-shaped photon detectors or pixels. All those detectors were built in a laboratory on the fourth floor of Iowa State's Zaffarano Physics Addition. The assembly took about $1 million and a lot of work by Iowa State post-doctoral researchers Martin Schroedter and Tomoyuki Nagai. The telescope system is based on techniques Iowa State researchers Richard Lamb and David Carter-Lewis helped develop in the 1980s. And now Krennrich says researchers are contemplating the next generation of gamma ray detection systems. Krennrich said researchers are assembling a worldwide collaboration to plan and build a $300 million, 36-telescope array. The new instrument would be known as AGIS (the Advanced Gamma-ray Imaging System) and would be 10 times more sensitive than VERITAS. Krennrich said Iowa State researchers are working on image-recognizing technology for the AGIS system that would help researchers by automatically separating gamma ray events from background events. The new instrument, Krennrich said, might finally produce the data that establishes the origins of gamma rays and cosmic rays. Iowa State University |
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| Related Gamma Rays Current Events and Gamma Rays News Articles Fermi large area telescope points the way to new millisecond pulsars The discovery of seventeen new millisecond pulsars was announced today at the American Astronomical Society Meeting by scientists from the Naval Research Laboratory (NRL) Space Science Division and a team of international researchers. Rare earth metal enhances phosphate glass Adding cerium oxide to phosphate glass rather than the commonly used silicate glass may make glasses that block ultraviolet light and have increased radiation damage resistance while remaining colorless, according to Penn State researchers. Fermi Sees Brightest-Ever Blazar Flare A galaxy located billions of light-years away is commanding the attention of NASA's Fermi Gamma-ray Space Telescope and astronomers around the globe. Cosmic rays hunted down A thin rain of charged particles continually bombards our atmosphere from outer space. The mysterious particles were first detected 100 years ago but until 10 years ago when a new type of telescope began to come online physicists weren't sure where the "cosmic rays" came from or how they were generated. Lightning-produced radiation a potential health concern for air travelers New information about lightning-emitted X-rays, gamma rays and high-energy electrons during thunderstorms is prompting scientists to raise concerns about the potential for airline passengers and crews to be exposed to harmful levels of radiation. A Superbright Supernova That's the First of Its Kind An extraordinarily bright, extraordinarily long-lasting supernova named SN 2007bi, snagged in a search by a robotic telescope, turns out to be the first example of the kind of stars that first populated the Universe. VERITAS telescopes help solve 100-year-old mystery: The origin of cosmic rays Nearly 100 years ago, scientists detected the first signs of cosmic rays - subatomic particles (mostly protons) that zip through space at nearly the speed of light. Starburst galaxy sheds light on longstanding cosmic mystery An international collaboration that includes scientists from the University of Delaware's Bartol Research Institute in the Department of Physics and Astronomy has discovered very-high-energy gamma rays in the Cigar Galaxy (M82), a bright galaxy filled with exploding stars 12 million light years from Earth. NASA's Fermi Telescope Detects Gamma-Ray From Nearby galaxies undergoing a furious pace of star formation also emit lots of gamma rays, say astronomers using NASA's Fermi Gamma-ray Space Telescope. Fermi telescope caps its first year with a glimpse of space-time During its first year of operations, NASA's Fermi Gamma Ray Space Telescope mapped the extreme sky with unprecedented resolution and sensitivity. More Gamma Rays Current Events and Gamma Rays News Articles |
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