WISE, Fermi Missions Reveal a Surprising Blazar Connection

NASA | AUGUST 27, 2016

Astronomers studying distant galaxies powered by monster black holes have uncovered an unexpected link between two very different wavelengths of the light they emit, the mid-infrared and gamma rays.

Black-hole-powered galaxies called blazars are the most common sources detected. Image credit: NASA/JPL-Caltech/GSFC

The discovery, which was accomplished by comparing data from NASA's Wide-field Infrared Survey Explorer (WISE) and Fermi Gamma-ray Space Telescope, has enabled the researchers to uncover dozens of new blazar candidates.

Francesco Massaro at the University of Turin in Italy and Raffaele D'Abrusco at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, show for the first time that the mid-infrared colors of blazars in WISE data correlate to an equivalent measurement of their gamma-ray output.

Blazars constitute more than half of the discrete gamma-ray sources seen by Fermi's Large Area Telescope (LAT). At the heart of a blazar lies a supersized black hole with millions of times the sun's mass surrounded by a disk of hot gas and dust.

As material in the disk falls toward the black hole, some of it forms dual jets that blast subatomic particles straight out of the disk in opposite directions at nearly the speed of light.

A blazar appears bright to Fermi for two reasons. Its jets produce many gamma rays, the highest-energy form of light, and we happen to be viewing the galaxy face on, which means one of its jets is pointing in our direction.

From January to August 2010, NASA's WISE mapped the entire sky in four infrared wavelengths, cataloging more than half a billion sources. In 2011, Massaro, D'Abrusco and their colleagues began using WISE data to investigate Fermi blazars.

About 1,000 Fermi sources remain unassociated with known objects at any other wavelength. Astronomers suspect many of these are blazars, but there isn't enough information to classify them.

The infrared/gamma-ray connection led the authors to search for new blazar candidates among WISE infrared sources located within the positional uncertainties of Fermi's unidentified gamma-ray objects. When the researchers applied this relationship to Fermi's unknown sources, they quickly found 130 potential blazars.

YOU MAY ALSO LIKE

Birds learn from each other’s ‘disgust’, enabling insects to evolve bright colours

A new study of TV-watching great tits reveals how they learn through observation. Social interactions within a predator species can have “evolutionary consequences” for potential prey – such as the conspicuous warning colours of insects like ladybirds.

Ancient lakes: eyes into the past, and the future

Modern, human-caused changes are accelerating threats to ancient lakes, these unique ecosystems.

Wine before beer, or beer before wine? Either way, you’ll be hungover

Most people will at some point in their life experience one of many the downsides of excess drinking: the hangover. Importantly, hangovers can lead to reduced productivity, impaired performance and even risk to daily tasks such driving or operating heavy machinery.

Study paves way for healthier and more robust eggs

The results of a study have enabled researchers to better understand the role of eggshells in embryo development and hatching.

No Winner in Milky Way-Andromeda Clash

Our Milky Way and the Andromeda galaxy—two giant galaxies in our local patch of the universe—are heading for an immense collision with each other in only a few billion years’ time.

Human Body Microbes Make Antibiotics, Study Finds

New research suggests that some of the bacteria that share our human bodies manufacture antibiotics and that these substances may be capable of fighting infection.