NASA's New View of Gamma-Ray Sky Honors Fermi
Logo for the Fermi Gamma-ray Space Telescope. Credit: NASA/Sonoma State University/Aurore Simonnet
NASA's newest observatory, the Gamma-Ray Large Area
Space Telescope, or GLAST, has begun its mission of exploring the
universe in high-energy gamma rays. The spacecraft and its
revolutionary instruments passed their orbital checkout with flying
NASA also announced that GLAST has been renamed the Fermi Gamma-ray
Space Telescope. The new name honors Prof. Enrico Fermi (1901 -
1954), a pioneer in high-energy physics.
"Enrico Fermi was the first person to suggest how cosmic particles
could be accelerated to high speeds," said Paul Hertz, chief
scientist for NASA's Science Mission Directorate at NASA Headquarters
in Washington. "His theory provides the foundation for understanding
the new phenomena his namesake telescope will discover."
Scientists expect Fermi will discover many new pulsars in our own
galaxy, reveal powerful processes near supermassive black holes at
the cores of thousands of active galaxies and enable a search for
signs of new physical laws.
For two months following the spacecraft's June 11 launch, scientists
tested and calibrated its two instruments, the Large Area Telescope
(LAT) and the GLAST Burst Monitor (GBM).
Click for larger, labeled image.
This all-sky view from GLAST reveals bright emission in the plane of the Milky Way (center), bright pulsars and super-massive black holes. Credit: NASA/DOE/International LAT Team
The LAT team today unveiled an all-sky image showing the glowing gas
of the Milky Way, blinking pulsars, and a flaring galaxy billions of
light-years away. The map combines 95 hours of the instrument's
"first light" observations. A similar image, produced by NASA's
Compton Gamma-ray Observatory in the 1990's, took years of observations
The image shows gas and dust in the plane of the Milky Way glowing in
gamma rays due to collisions with accelerated nuclei called cosmic
rays. The famous Crab Nebula and Vela pulsars also shine brightly at
these wavelengths. These fast-spinning neutron stars, which form when
massive stars die, were originally discovered by their radio
emissions. The image's third pulsar, named Geminga and located in
Gemini, is not a radio source. It was discovered by an earlier
gamma-ray satellite. Fermi is expected to discover many more
radio-quiet pulsars, providing key information about how these exotic
A fourth bright spot in the LAT image lies some 7.1 billion
light-years away, far beyond our galaxy. This is 3C 454.3 in Pegasus,
a type of active galaxy called a blazar. It's now undergoing a
flaring episode that makes it especially bright.
The LAT scans the entire sky every three hours when operating in
survey mode, which will occupy most of the telescope's observing time
during the first year of operations. These fast snapshots will let
scientists monitor rapidly changing sources.
Click image for video. (Video Description)
Astronomers wrapped the Fermi Gamma-ray Space Telescope's first all-sky map over a sphere to produce this view of the gamma-ray universe. Credit: NASA/DOE/International LAT Team
The instrument detects photons with energies ranging from 20 million
electron volts to over 300 billion electron volts. The high end of
this range, which corresponds to energies more than 5 million times
greater than dental X-rays, is little explored.
The spacecraft's secondary instrument, the GBM, spotted 31 gamma-ray
bursts in its first month of operations. These high-energy blasts
occur when massive stars die or when orbiting neutron stars spiral
together and merge.
The GBM is sensitive to less energetic gamma rays than the LAT. Bursts
seen by both instruments will provide an unprecedented look across a
broad gamma-ray spectrum, enabling scientists to peer into the
processes powering these events.
NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle
physics partnership, developed in collaboration with the U.S.
Department of Energy, along with important contributions from
academic institutions and partners in France, Germany, Italy, Japan,
Sweden and the U.S.
GLAST Website (http://glast.gsfc.nasa.gov/)
GLAST Education Pages (http://glast.sonoma.edu)