An artist's depiction of a star and its companion black hole, known as an X-ray binary system. These systems were responsible for heating the early universe in the first few hundred million years ... more 
An artist's depiction of a star and its companion black hole, known as an X-ray binary system. These systems were responsible for heating the early universe in the first few hundred million years after the Big Bang. less 
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SPACE.com | Photo By ESA, NASA, Felix Mirabel
Wed, Feb 5, 2014 1:10 PM EST