The Milagro Gamma-Ray Observatory
Milagro, the Spanish word for miracle, is a new type of astronomical
telescope. Like conventional telescopes, Milagro is sensitive to light
but the similarities end there. Whereas "normal" astronomical
telescopes view the Universe in visible light, Milagro "sees"
the Universe at very high energies. The "light" that Milagro
sees is about 1 trillion times more energetic than visible light. While
these particles of light, known as photons, are the same as the photons
that make up visible light, they behave quite differently simply because
they are much more energetic.
(Click image to view enlarged photo)
What is Milagro?
Milagro is a large pool of water (about the size of a football field),
covered with a light-tight barrier, instrumented with 723 light-sensitive
detectors known as photo-multiplier tubes (PMTs). Below is a picture
of Milagro taken when the cover was inflated. We inflate the cover to
work on the detector.
(Click image to view enlarged photo)
Why Milagro?
When one views the heavens in high-energy photons the
picture is quite different from what we see when we look up at the night
sky. The number of objects we see are much fewer and much more "extreme".
We see supermassive black holes and neutron stars. Some of these sources
are known to be highly variable, flaring on timescale of minutes to
days. In addition we hope to discover new sources of TeV photons, possibly
observe TeV emission from Gamma-Ray Bursts, discover primordial black
holes, or discover completely new phenomena. Until the advent of Milagro
there was no instrument capable of continuously monitoring the entire
overhead sky in the TeV energy regime. The existing instruments had
to be pointed at small regions of the sky (usually known sources) and
could only look at a source during the time of year it was overhead
at night. Even then they could only look at the source if the weather
was good and the moon was set. Milagro is ideally suited to monitor
the variable TeV Universe and discover new sources of TeV gamma rays.
In the following pages we will explain how we "see"
these photons and what they may tell us about the Universe. To learn
more about Milagro follow the links on this page and in the navigation
frame on the left.
Acknowledgements
Milagro was made possible by the generous support of the
National Science Foundation, the Department of Energy, Los Alamos National
Laboratory, and the University of California.
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