EVANSTON, Ill., April 13 -- Astronomers at Northwestern University and the University of Illinois have detected the first observational evidence of the remnants of hypernovae. These explosions are a hundred times more energetic than supernovae and may be the source of powerful gamma ray bursts, making them the most energetic events known in the Universe after the Big Bang.Daniel Wang, research assistant professor of physics and astronomy at Northwestern University, identified two hypernova remnants in galaxy M101 (also known as the Pinwheel galaxy for its distinctive spiral shape). These remnants had been classified as supernova remnants, nebulae or clouds; however, Wang's detection and analysis of X-ray light from the nebulae pointed to a more energetic process. Wang relied primarily on data from the German/US/UK joint mission ROSAT X-ray satellite, and on the work of Professor You-Hua Chu of the University of Illinois, whose team made detailed optical observations of the two remnants using the Hubble Space Telescope and the 4-m telescope at Kitt Peak National Observatory.