Gamma Ray Antimatter

1. Gamma Ray Antimatter Instrument: CGRO OSSE Credit: W. Purcell (NWU) et al. This mysterious cloud of gamma rays glows in the center of the Milky Way, produced by annihilating antimatter particles. It is probably about 4,000 light-years across and extends nearly 3,500 light-years above the galactic center. Associated with no previously known object, the cloud seems to imply that a fountain of antimatter positrons streams from the galactic center, perhaps from neutron star collisions or black holes.

2. The Search for Dark Matter Superposed on an optical image of a group of galaxies is an image taken in X-ray light, showing confined hot gas in false purple color. Is the gravity of the galaxies high enough to contain the glowing hot gas? The extra gravity needed is attributed to dark matter, the nature and abundance of which is the biggest mystery in astronomy today. Instrument: ROSAT data Credit: R. Mushotzky, NASA/GSFC; ESA

3. The North Ecliptic Pole The North Ecliptic Pole (shown here at 0.5-1.6 keV) and the South Ecliptic Pole are the two locations visible to ROSAT at any time, being perpendicular to the plane of the Earth's orbit. Because of the survey geometry, the ecliptic poles were covered every orbit, leading to the bright region at the center of the field. The ROSAT PSPC ribs and central ring are partially visible as the dark nearly linear areas pointing to the upper left of the image. 10 arcmin Instrument: ROSAT PSPC Credit: MPE

4. The North Ecliptic Pole The North Ecliptic Pole (shown here at 0.5-1.6 keV) and the South Ecliptic Pole are the two locations visible to ROSAT at any time, being perpendicular to the plane of the Earth's orbit. Because of the survey geometry, the ecliptic poles were covered every orbit, leading to the bright region at the center of the field. KAZ 102, an optically bright, radio quiet quasar is visible towards the top of the image. 30 arcmin Instrument: ROSAT PSPC Credit: MPE

5. The South Ecliptic Pole The South Ecliptic Pole (shown here in X-ray) and the North Ecliptic Pole are the two locations that are visible to ROSAT at any time, being perpendicular to the plane of the Earth's orbit. Because of the survey geometry, the ecliptic poles were covered every orbit, leading to the bright region at the center of the field. The Large Magellanic Cloud is the bright extended region to the lower right of the ecliptic pole. 2 degrees Instrument: ROSAT PSPC Credit: MPE

6. Ophiuchus Dark Clouds This mosaic of the Ophiuchus Dark Clouds in the 3/4 keV band is remarkable in the detailed structure of the diffuse X-ray background and tight negative correlation between the cloud material and the surface brightness of the X-rays. The origin of the strong back-lighting of these clouds might be either emission from Loop I (a nearby supernova remnant or stellar wind bubble) or the Galactic bulge. 2 degrees Distance: 450 light-years Instrument: ROSAT PSPC Credit: S.L. Snowden, NASA/GSFC

7. Gamma Ray Burst Gamma ray bursts occur with no warning, last only a few seconds, and produce more energy in that short period than the entire Universe combined. On January 23, 1999, ROTSE captured the first-ever optical images a burst at the very moment it was going off. Other telescopes captured its afterglow, as shown here. Instrument: HST Credit: STScI

8. Gamma Ray Burst, Caught in Optical On January 23, 1999, ROTSE captured first-ever optical images a gamma-ray burst at the very moment the burst was going off -- the “Holy Grail” for the hunters of these mysterious explosions, which occur with no warning, last only a few seconds, and produce more energy in that short period than the entire Universe combined. Instrument: ROTSE Credit: ROTSE team

9. The North Polar Spur The North Polar Spur -- perhaps the most spectacular coherent structure in the soft X-ray sky -- was completely mapped for the first time at high resolution in the ROSAT/PSPC survey. The North Polar Spur is part of a hot interstellar bubble created by winds of young, hot stars and several supernova explosions. Instrument: ROSAT PSPC Credit: R. Egger, MPE 10 degrees

10. The Compton Observatory The Compton Gamma Ray Observatory satellite with solar panels unfurled is pictured here high above western Africa just prior to its release into orbit. The large round domes of the EGRET (bottom) and COMPTEL (center) experiments are visible in this view along with four of the eight BATSE detectors located at the corners of the satellite. The OSSE experiment housing is visible just above the COMPTEL dome. Credit: NASA

11. Diffuse X-ray Spectrometer The Diffuse X-Ray Spectrometer (DXS) experiment was flown as an attached payload in the January 1993 flight of Space Shuttle Endeavor. Developed by the University of Wisconsin, the DXS was designed primarily to detect the diffuse X-ray background with roughly 10 eV energy resolution and 15 degree angular resolution. Credit: NASA

12. The Solar Max Mission The Solar Maximum Mission (SMM), launched in February 1980 to study the Sun during the high part of the solar cycle, carried two high energy experiments: the Hard X-ray Burst Spectrometer and theGamma-Ray Spectrometer. A malfunction in the satellite in 1981 halted the original mission. The space shuttle Challenger serviced the SMM in orbit in 1984, which enabled the satellite to function through 1989. Credit: NASA

13. Spartan-1 Spartan-1 was designed to be deployed from the space shuttle Discovery and then recovered after 2 days in orbit. Aboard the Spartan platform were X-ray detectors sensitive to the energy range 1-12 keV. Launched in June 1985, Spartan-1 observed the Perseus cluster of galaxies and our galactic center region. Credit: NASA