By Ron Cowen
To announce their arrival, black holes give off a birth cry—an energetic flash of light known as a gamma-ray burst. Now, astronomers have evidence that just minutes later, the newborns emit powerful X-ray burps as well.
NASA’s Swift spacecraft is the first to record these never-before-seen hiccups because it can slew its X-ray telescope to just the right patch of sky immediately after the craft detects a gamma-ray burst. One of the newly detected X-ray flares, recorded 12 minutes after a gamma-ray burst on May 2, packed about as much energy as the burst itself. David N. Burrows and Peter Mészáros of Pennsylvania State University in State College and 32 colleagues describe their findings in an upcoming Science.