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NASA’s Fermi Finds Giant, Previously Unseen Structure In Our Galaxy: Briefing Materials
11.09.10
 
NASA will hold a media teleconference at 2:30 p.m. EST on Tuesday, Nov. 9, 2010, to discuss a new discovery by the Fermi Gamma-ray Space Telescope. Gamma rays are the highest-energy form of light. The soon-to-be published findings include the discovery of enormous but previously unrecognized "gamma-ray bubbles" centered in the Milky Way.

Audio of the teleconference is being streamed live on NASA's website at:

http://www.nasa.gov/newsaudio



Briefing Speakers


› Jon Morse, director, Astrophysics Division, NASA Headquarters, Washington, D.C.
› Julie McEnery, Fermi project scientist, NASA's Goddard Space Flight Center, Greenbelt, Md.
› Doug Finkbeiner, associate professor of astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.
› Simona Murgia, Fermi research associate, SLAC National Accelerator Laboratory, Menlo Park, Calif.
› David Spergel, chair, Department of Astrophysical Sciences, Princeton University, Princeton, N.J.



Images and Multimedia in Support of the News Conference


Presenter 1: Jon Morse, director, Astrophysics Division, NASA Headquarters, Washington, D.C.

No visuals.



Presenter 2: Julie McEnery, Fermi project scientist, NASA's Goddard Space Flight Center, Greenbelt, Md.

Visual 1: This all-sky image, constructed from two years of observations by NASA's Fermi Gamma-ray Space Telescope, is the deepest and best-resolved portrait of the gamma-ray sky to date. The view shows how the sky appears at energies greater than 1 billion electron volts (1 GeV). For comparison, the energy of visible light is between 2 and 3 electron volts. A diffuse glow fills the sky and is brightest along the plane of our galaxy (middle). Discrete gamma-ray sources include pulsars and supernovae remnants within our galaxy as well as distant galaxies powered by supermassive black holes. Credit: INASA/DOE/Fermi LAT Collaboration
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Visual 2: Electrons moving near the speed of light are an important source of the Milky Way's diffuse gamma-ray glow; they also power a new galactic structure uncovered in Fermi data. When a relativistic electron strikes a low-energy (radio or infrared) photon, the collision slightly slows the electron and ramps up the photon to gamma-ray energies. Credit: NASA Goddard
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Visual 3: When an electron moving near the speed of light strikes a low-energy photon, the collision slightly slows the electron and boosts the photon's energy to the gamma-ray regime. Credit: NASA Goddard
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Presenter 3: Doug Finkbeiner, associate professor of astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.

gamma-ray structure visible by processing Fermi all-sky data at energies from 1 to 10 GeV

Visual 1: A giant gamma-ray structure emerges by processing Fermi all-sky data at energies from 1 to 10 GeV. The dumbbell-shaped feature emerges from the galactic center and extends 50 degrees north and south from the plane of the Milky Way. A supermassive black hole weighing about 4 million times the sun's mass also lurks in the galactic center; these "gamma-ray bubbles" may have arisen as a result of a past eruption by the black hole or another source near the galactic center. Credit: NASA/DOE/Fermi LAT/D. Finkbeiner et al.
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Visual 2: Data from the Fermi Large Area Telescope (LAT) unveil the new feature after several processing steps, illustrated here. First, the data are smoothed to eliminate features smaller than 2 degrees across, then the contrast is increased (stretched). Even without additional processing, the edge of the southern bubble can be seen. Next, astronomers mask out bright point sources, such as pulsars and distant galaxies. Then, using models developed from Fermi LAT observations, astronomers remove the diffuse gamma-ray emission from the image. This reveals the entire new structure, which is further brightened by another contrast stretch. Credit: NASA/DOE/Fermi LAT/D. Finkbeiner et al.
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illustration of gamma-ray bubbles extent Visual 3: From end to end, the gamma-ray bubbles extend 50,000 light-years, or roughly half of the Milky Way's diameter, as shown in this illustration. The bubbles stretch across 100 degrees, spanning the sky from the constellation Virgo to the constellation Grus. If the structure were rotated into the galaxy's plane, it would extend beyond our solar system. Hints of the bubbles' edges were first observed in X-rays (blue) by ROSAT (RÖntgen SATellite), a Germany-led mission operating in the 1990s. The gamma rays mapped by Fermi (magenta) extend much farther from the galaxy's plane. Credit: NASA Goddard
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Fermi all-sky data with superimposed graphs Visual 4: The bubbles display a much more energetic ("harder") spectrum (left), with peak energies around 10 GeV, than the diffuse gamma-ray glow seen throughout the sky. Astronomers estimate that the electrons responsible for the bubble emission must have energies greater than 500 GeV. In addition, the bubbles display edges less than 2 degrees wide in Fermi LAT data. Both of these qualities suggest that the structure arose in a sudden, impulsive event, such as an eruption from the Milky Way's black hole or a rapid surge of star formation in the galactic center. Credit: NASA/DOE/Fermi LAT/D. Finkbeiner et al.
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Presenter 4: Simona Murgia, Fermi research associate, SLAC National Accelerator Laboratory, Menlo Park, Calif.

No visuals.



Presenter 5: David Spergel, chair, Department of Astrophysical Sciences, Princeton University, Princeton, N.J.

No visuals.



Related Links


For a related feature article with video and images, visit:
www.nasa.gov/mission_pages/GLAST/news/new-structure.html

For a related press release version version, visit:
www.nasa.gov/home/hqnews/2010/nov/HQ_10-295_FERMI.html