Each point in this image represents an object that emits x-ray radiation strong enough to be detected by the High Energy Astronomical Observatory (HEAO) satellite. False colors were used to distinguish different types of objects: white for normal stars in our galaxy; blue for supernova remnants; green for binary star systems where one member is a neutron star or black hole; yellow for sources outside our galaxy, such as active galaxies and quasars; pink for the hot gas in intergalactic space; and red for unidentified objects. The size of the points indicates the intensity of their x-ray emission. 
    X-rays are a highly energetic radiation, associated with objects under extreme conditions. They are generally produced either by gas at