Gamma-ray bursts (GRBs) are short-lived bursts of gamma-ray light,
the most energetic form of light. Lasting anywhere from a few
milliseconds to several minutes, GRBs shine hundreds of times brighter
than a typical supernova and about a million trillion times as bright as
the Sun. When a GRB erupts, it is briefly the brightest source of cosmic
gamma-ray photons in the observable Universe.
This video shows the first 500 bursts
detected by Swift and identifies some of the more notable
Until recently, GRBs were arguably the biggest mystery in high-energy
astronomy. They were discovered serendipitously in the late 1960s by
U.S. military satellites which were on the lookout for Soviet nuclear
testing in violation of the atmospheric nuclear test ban treaty. These
satellites carried gamma ray detectors since a nuclear explosion
produces gamma rays. They didn't find any violations of the nuclear
treaty, but they did discover bright bursts of gamma rays from beyond
the solar system.
Evidence from recent satellites like Swift and Fermi indicate that
the energy behind a gamma-ray burst comes from the collapse of matter
into a black hole.
Two types of GRBs
When astronomers looked at the number of bursts versus how long they
lasted, they found two different classes of bursts: long-duration and
short-duration. These two classes are likely created by different
processes, but the end result in both cases is a brand new black
Graph of the time versus number of bursts
for the gamma-ray bursts observed by the BATSE instrument on the
Compton Gamma-ray Telescope.
Long-duration bursts last anywhere from 2 seconds to a few
hundreds of seconds (several minutes), with an average time of about 30
seconds. They are associated with the deaths of massive stars in
supernovas; though not every supernova produces a gamma-ray burst.
Short duration bursts are those that last less then 2 seconds;
lasting anywhere from a few milliseconds to 2 seconds with an average
duration of about 0.3 seconds (or 300 milliseconds). These bursts appear
to be associated with the merger of two neutron stars into a new black
hole or a neutron star with a black hole to form a larger black
The Imagine Team
Project Leader: Dr. Barbara Mattson
Curator: Meredith Gibb
Responsible NASA Official: Phil Newman
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