Continuing our top 10 ranges, today we will write about top 10 largest cities in the world by land area.
The universe is filled with high-energy radiation, much of which is made of gamma rays
belched out by strange pulsing stars and the remnants of supernova explosions. But nearly one-third of all gamma-ray emitting objects seen to date defy identification. The objects were spotted by NASA’s Fermi Gamma-ray Space Telescope, which scans the entire sky over the course of three hours, mapping the powerful spectrum. When stacked together, the surveys create an extremely precise view of the gamma-ray universe. Scientists then match these images to other observations to identify each source. But the identities of some gamma-ray sources in space still continue to elude the astronomers. According to David Thompson, Fermi’s deputy project scientist there’s some that, despite all their efforts, they really do not know what they are.They do not seem to be any of the usual suspects.The Fermi space telescope has spotted nearly 500 powerful gamma-ray sources in deep space over the last three years. Half of them are active galaxies. According to researchers pulsars and supernova remnants each make up about 5 percent of the sources, with high-mass binary stars and other galaxies contributing just a smidge more. But a large collection of objects remains unidentified. As said Pascal Fortin, at the Ecole Polytechnique’s Laboratoire Leprince-Ringuet in France deeper observations at other wavelengths could find counterparts to some Fermi sources in the future. According to researchers one potential cause of the baffling readings could be black holes that are interacting in a new and unexpected way. If the strange objects reveal nothing else, they highlight how much of space is still a mystery.
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