By: Courtney Lee & Kristel Curameng
Short-lived bursts of
gamma-ray photons.
 Gamma-ray photons
are the most
energetic form of
light.
 Some are associated
with special types of
supernovae.
 Supertnovae are
explosions marking
the deaths of
massive stars.

Lasts anywhere from a few
milliseconds to several
minutes.
 Shines hundreds of times
brighter than a typical
supernova.
 Shines about a million trillion
times as bright as the Sun.
 Gamma-Ray Bursts are briefly
the brightest source of
cosmic gamma-ray photons in
the observable universe.

 About
once a day, the
sky is lit up by a
brilliant flash of
energy.
 It comes from random
directions, different
every time.
 Brightest objects in
the sky.
 Human eyes cannot
detect Gamma-ray
bursts.
The closest Gamma-ray burst known to date is
over a hundred million light-years away.
 Most of them come from billions of light years.
 They outshine our closest stars in our sky from
distances that are billions of times further away.
 Stupendous amounts of energy are required.

 Discovered
in the late 1960s by U.S. military
satellites.
 The satellites carried gamma-ray detectors
since a nuclear explosion produces gamma
rays.
 Gamma-ray
bursts used to be the biggest
mystery in high-energy astronomy.
 In the early 1900s, astronomers didn’t know
if they originated at the edge of our solar
system, in our Milky Way Galaxy, or far away
near the edge of the observable universe.
 Today, satellite observations, follow-up
ground-based observations, and theoretical
work have allowed astronomers to link
Gamma-Ray Bursts to supernovae in distant
galaxies.
 Most
Gamma-ray bursts come from other
galaxies.
 Often from among the most distant galaxies
in the known universe.
 No
one knows for sure
 Our best theory is based upon several
observed facts:
 The only way to generate huge quantities is
via gravitational collapse, and black holes
can be very efficient at turning this energy
into explosive power.
 Some of the closest GRBs appear to occur
simultaneously with supernovae
 Almost all GRBs happen in galaxies
containing large numbers of very massive
stars.
Short Gamma-ray bursts





a duration of less than about two seconds
Are more rare, and astronomers were never able to
detect an afterglow of a burst until recently.
The blast of energy only lasts for a few microseconds
and then it’s gone.
shorter bursts have no detected afterglow in X-rays
or visible light.
short GRBs may happen when two objects called
neutron stars merge together, to form an even more
bizarre object, a black hole. Or perhaps, some
thought, a previously-formed black hole swallowed a
neutron-star companion.
Long Gamma-ray burst




have a duration of greater than two seconds
They are vast majority of explosions caused by a
core-collapse supernova.
This is when a star many times larger than our own
Sun runs out of fuel and then collapses inward to
form a black hole. This also releases a massive
outburst of energy that shines clear across the
Universe.
Almost every well-studied long gamma-ray burst has
been associated with a rapidly star-forming galaxy
and in many cases a core-collapse supernova
 "Gamma-ray
Bursts: Introduction to a
Mystery." Imagine The Universe! Home Page.
Web. 18 Apr. 2011.
<http://imagine.gsfc.nasa.gov/docs/science
/know_l1/bursts.html>.
 "Gamma-Ray Bursts." UC Berkeley Astronomy
Department Home. Web. 18 Apr. 2011.
<http://astro.berkeley.edu/research/grbs/g
rbinfo.html>.
 "Gamma Ray Burst." Universe Today. Web. 18
Apr. 2011.
<http://www.universetoday.com/73564/gam