April 14, 2012
NASA Scientists Hunting Blazars Using WISE Telescope
The hunt is on for a class of supermassive black holes, as scientists at NASA are using a infrared-wavelength astronomical space telescope in order to hunt-down the compact quasars typically associated with the phenomenon, officials at the US space agency revealed on Thursday.
Using data obtained from the Wide-field Infrared Survey Explorer (WISE), astronomers have discovered more than 200 of these blazing quasi-stellar objects, and the potential is there to find thousands of additional blazars, which NASA officials say are among the most energetic objects in the entire universe.
According to NASA, blazars consist of supermassive black holes which actively draw matter into them, and as that matter is pulled within the black hole, a percentage of the energy is released in the form of jets which travel close to the speed of light. What makes these objects special is that they are visible to us here on Earth.
"Blazars are extremely rare because it's not too often that a supermassive black hole's jet happens to point towards Earth," Francesco Massaro, lead investigator of the study and a member of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), said in a statement. "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."
Massaro and his colleagues used information catalogued by WISE during a survey of the celestial sky using infrared light. That survey, which took place in 2010, covered an estimated hundreds of millions of various interstellar objects. Using portions of that data released in April of last year, they tested a theory that they could use the ultra-powerful telescope to detect 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," NASA officials said. "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."
They were also able to find 50 entities which could also be blazars, and once they analyze the remainder of the WISE data, which was recently released to scientists, Massaro believes that they could discover thousands more. Multiple papers detailing their findings to date have been published in the Astrophysical Journal.
Co-author Raffaele D'Abrusco of the Harvard Smithsonian Center for Astrophysics (CFA) called the findings "a significant step toward unveiling the mystery of the many bright gamma-ray sources that are still of unknown origin," and Peter Eisenhardt, WISE project scientist at NASA's California-based Jet Propulsion Laboratory (JPL), added, "We had no idea when we were building WISE that it would turn out to yield a blazar gold mine“¦ That's the beauty of an all-sky survey. You can explore the nature of just about any phenomenon in the universe."
Image 1: This artist's concept shows a "feeding," or active, supermassive black hole with a jet streaming outward at nearly the speed of light. Such active black holes are often found at the hearts of elliptical galaxies. Not all black holes have jets, but when they do, the jets can be pointed in any direction. If a jet happens to shine at Earth, the object is called a blazar. Image credit: NASA/JPL-Caltech
Image 2: This image taken by NASA's Wide-field Infrared Survey Explorer (WISE) shows a blazar -- a voracious supermassive black hole inside a galaxy with a jet that happens to be pointed right toward Earth. These objects are rare and hard to find, but astronomers have discovered that they can use the WISE all-sky infrared images to uncover new ones. So far, researchers have found more than 200 new blazars, and they say WISE has the potential to find many more. Image credit: NASA/JPL-Caltech/Kavli