Mystery rays could be sign of cosmic strings

 作者:隗蜗     |      日期:2019-03-15 07:11:01
By Marcus Chown THE mysterious gamma rays that emanate from the central bulge of our galaxy could arise from a seething tangle of “cosmic strings”. The gamma rays have a distinctive energy of 511 kiloelectronvolts, suggesting they are formed by the mutual annihilation of electrons and their antimatter counterparts, positrons. But where do the positrons come from? “This is the big mystery,” says Tanmay Vachaspati, a string theorist at Case Western Reserve University in Cleveland, Ohio. Previous candidates for positron sources have included astrophysical entities, such as supernovae, black holes and neutron stars,