Blazar's brightness cycle confirmed by NASA's Fermi mission

A two-year cycle in the gamma-ray brightness of a blazar, a galaxy powered by a supermassive black hole, has been confirmed by 10 years of observations from NASA's Fermi Gamma-ray Space Telescope. The findings were announced today at the Eighth International Fermi Symposium meeting this week in Baltimore.

"This is the first time that a gamma-ray period has been confirmed in an active galaxy," said Stefano Ciprini, a researcher at the INFN Tor Vergata division of the Italian Space Agency's Space Science Data Center in Rome. "The gamma-ray period is also seen in other wavebands, including visible light, and additional X-ray and radio data hint at similar brightness peaks."

Some of the matter falling into the blazar, named PG 1553+113, forms a jet of particles that radiates gamma rays, the highest-energy form of light, almost directly toward Earth.

Continued...
Source

Credits: NASA's Goddard Space Flight Center/CI Lab

Fermi observations suggest possible years-long cyclic changes in gamma-ray emission from the blazar PG 1553+113. The graph shows Fermi Large Area Telescope data from August 2008 to July 2015 for gamma rays with energies above 100 million electron volts (MeV).

For comparison, visible light ranges between 2 and 3 electron volts. Vertical lines on data points are error bars. Background: One possible explanation for the gamma-ray cycle is an oscillation of the jet produced by the gravitational pull of a second massive black hole, seen at top left in this artist's rendering.

Source / Image Courtesy

The gamma rays came from a galaxy known as PKS 1441+25, a type of active galaxy called a blazar. Located toward the constellation Boötes, the galaxy is so far away its light takes 7.6 billion years to reach us.

At its heart lies a monster black hole with a mass estimated at 70 million times the sun's and a surrounding disk of hot gas and dust. If placed at the center of our solar system, the black hole's event horizon -- the point beyond which nothing can escape -- would extend almost to the orbit of Mars.

NASA's Fermi Gamma-ray Space Telescope has identified the farthest gamma-ray blazars, a type of galaxy whose intense emissions are powered by supersized black holes.

Light from the most distant object began its journey to us when the universe was 1.4 billion years old, or nearly 10 percent of its present age.