Look, There in the Sky! It's a Gamma-Ray
Look, There in the Sky! It's a Gamma-Ray Burster?
What exactly is the source of a gamma-ray burst? Since their
discovery in the early 1970s, nobody has been able to explain the cause of the
mysterious flash of gamma-rays called a gamma-ray burst that seems to come
from a random direction on the sky. Worse yet, it is even unclear whether
these high-energy explosions originate in our own Galaxy or in distant
galaxies across the Universe. Now, all of that may have changed!
On February 28, the Italian/Dutch satellite known as
BeppoSAX detected what may well be X-rays from a burst source, eight hours
after the gamma-ray flash. The discovery image from BeppoSAX, ISA, and ESA is
shown above. Even later, using the position provided by this X-ray image,
ground-based telescopes discovered a variable optical source which also seems
to be related to the burster. Dramatically, this optical transient has now
faded. In its place lies a steady source which appears to be a dim, distant
Did the gamma-ray burst originate in the distant galaxy? If so, it answers one
facet of one of modern astronomy's greatest controversies. If not, this
would not be the first fortuitous coincidence to mislead astronomers. Only
repeated observations of events such as those seen by BeppoSAX and ground-based observatories will be able to determine if this is a major
breakthrough for high-energy astronomy or just frustratingly bad luck.
For more information, see the press release from the Italian Space Agency (http://bepposax.gsfc.nasa.gov/bepposax/first/pressrel_12-mar-97.html)