Scientists Spot Powerful Gamma Rays That Are Older Than Earth

Posted: Dec 15 2015, 9:04pm CST | by , Updated: Dec 16 2015, 10:30pm CST, in News | Latest Science News


Scientists Spot Powerful Gamma Rays that are Older than Earth
The artistic impression of a blazar, the core of an active galaxy powered by a supermassive black hole. Credit: M. Weiss/CfA

The flare of high energy gamma rays is emitted from a galaxy halfway across the universe.

NASA scientists have spotted a flare of very high energy gamma rays, which was generated by a distant galaxy and traveled for about half the age of the universe. 

When the flood of powerful gamma rays slammed the atmosphere of Earth, it produced a cascade of light. This is the first time when such high energy light has ever been detected from a galaxy so distant. These observations will provide a unique look into that faraway galaxy and the black hole existing in the galactic center.

The galaxy, known as PKS 1441+25, belongs to rare type of galaxy called blazer. Blazers are tremendously bright galaxies powered by a supermassive black hole at the heart and they can emit flares 10 to 100 times brighter than their baseline light emissions. 

A similar kind of powerful flood of gamma rays emitted from PKS 1441+25 began its journey to Earth a long time ago before the formation of Earth and arrived in April this year. Scientists observed the outburst using a range of telescopes sensitive to different wavelengths including Fermi Gamma-ray Space Telescope and Very Energetic Radiation Imaging Telescope Array System (VERITAS) in Arizona.

“With VERITAS, we detected gamma rays from this unusual object at the highest energies observed on Earth.” Lead researcher Jonathan Biteau from University of California, Santa Cruz said.

Detecting such high energy gamma rays that covered such a long distance was unexpected for scientists because they face a good chance of being annihilated at some point during 7.6 billion years when they traveled towards Earth. 

Gamma rays are photons of light with very high energies. When these high energy photons collide with lower energy photons, they get destroyed. For becoming detectable through telescopes, these gamma rays must have avoided tight nets of photons surrounding the black hole and a loose net of photons from extragalactic background light (EBL) a faint haze of light which is filled in universe. It usually absorbs high energy rays as they travel through space. The study also suggests that the gamma rays must have been emitted from a source distant to a black hole.

"If the gamma rays were produced close to the black hole, the radiation fields there are strong enough to absorb them. So the fact that the gamma rays are getting out of the galaxy at all indicates they were produced farther away from the black hole.” co-author David Williams said.

The observations provide clues to how and where such gamma rays are produced and how the environment near supermassive black hole looks like.

Jonathan Biteau said. "This is clearly the opening of a new era where we can compare source-by-source measurements and start to probe the cosmic evolution of the extragalactic background light.”

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Hira Bashir covers daily affairs around the world.




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