FROM: NASA
WASHINGTON -- Astronomers are actively hunting a class of supermassive
black holes throughout the universe called blazars thanks to data
collected by NASA's Wide-field Infrared Survey Explorer (WISE). The
mission has revealed more than 200 blazars and has the potential to
find thousands more.
Blazars are among the most energetic objects in the universe. They
consist of supermassive black holes actively "feeding," or pulling
matter onto them, at the cores of giant galaxies. As the matter is
dragged toward the supermassive hole, some of the energy is released
in the form of jets traveling at nearly the speed of light. Blazars
are unique because their jets are pointed directly at us.
"Blazars are extremely rare because it's not too often that a
supermassive black hole's jet happens to point towards Earth," said
Franceso Massaro of the Kavli Institute for Particle Astrophysics and
Cosmology near Palo Alto, Calif., and principal investigator of the
research, published in a series of papers in the Astrophysical
Journal. "We came up with a crazy idea to use WISE's infrared
observations, which are typically associated with lower-energy
phenomena, to spot high-energy blazars, and it worked better than we
hoped."
The findings ultimately will help researchers understand the extreme
physics behind super-fast jets and the evolution of supermassive
black holes in the early universe.
WISE surveyed the entire celestial sky in infrared light in 2010,
creating a catalog of hundreds of millions of objects of all types.
Its first batch of data was released to the larger astronomy
community in April 2011 and the full-sky data were released last
month.
Massaro and his team used the first batch of data, covering more than
one-half the sky, to test their idea that WISE could identify
blazars. Astronomers often use infrared data to look for the weak
heat signatures of cooler objects. Blazars are not cool; they are
scorching hot and glow with the highest-energy type of light, called
gamma rays. However, they also give off a specific infrared signature
when particles in their jets are accelerated to almost the speed of
light.
One of the reasons the team wants to find new blazars is to help
identify mysterious spots in the sky sizzling with high-energy gamma
rays, many of which are suspected to be blazars. NASA's Fermi mission
has identified hundreds of these spots, but other telescopes are
needed to narrow in on the source of the gamma rays.
Sifting through the early WISE catalog, the astronomers looked for the
infrared signatures of blazars at the locations of more than 300
gamma-ray sources that remain mysterious. The researchers were able
to show that a little more than half of the sources are most likely
blazars.
"This is a significant step toward unveiling the mystery of the many
bright gamma-ray sources that are still of unknown origin," said
Raffaele D'Abrusco, a co-author of the papers from Harvard
Smithsonian Center for Astrophysics in Cambridge, Mass. "WISE's
infrared vision is actually helping us understand what's happening in
the gamma-ray sky."
The team also used WISE images to identify more than 50 additional
blazar candidates and observed more than 1,000 previously discovered
blazars. According to Massaro, the new technique, when applied
directly to WISE's full-sky catalog, has the potential to uncover
thousands more.
"We had no idea when we were building WISE that it would turn out to
yield a blazar gold mine," said Peter Eisenhardt, WISE project
scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena,
Calif., who is not associated with the new studies. "That's the
beauty of an all-sky survey. You can explore the nature of just about
any phenomenon in the universe."
FROM: NASA
