Star-forming galaxies are responsible for creating gamma-rays that until now had not been associated with a known origin.
Star-forming galaxies are responsible for creating gamma-rays that until now had not been associated with a known origin, researchers from The Australian National University (ANU) have confirmed.
Lead author Dr. Matt Roth, from the ANU Research School of Astronomy and Astrophysics, said until now it has been unclear what created gamma-rays — one of the most energetic forms of light in the Universe — that appear in patches of seemingly ’empty sky’.
The discovery could offer clues to help astronomers solve other mysteries of the Universe, such as what kind of particles make up Dark Matter — one of the holy grails of astrophysics.
“It’s a significant milestone to finally discover the origins of this gamma-ray emission, solving a mystery of the Universe astronomers have been trying to decipher since the 1960s,” Dr. Roth said.
“There are two obvious sources that produce large amounts of gamma-rays seen in the Universe. One when gas falls into the supermassive black holes which are found at the centers of all galaxies — called an active galactic nucleus (AGN) — and the other associated with star formation in the disks of galaxies.
“We modeled the gamma-ray emission from all the galaxies in the Universe and compared our results with the predictions for other sources and found that it is star-forming galaxies that produce the majority of this diffuse gamma-ray radiation and not the AGN process.”
ANU researchers were able to pinpoint what created these mysterious gamma rays after obtaining a better understanding of how cosmic rays — particles that travel at speeds very close to the speed of light — move through the gas between the stars. Cosmic rays are important because they create large amounts of gamma-ray emission in star-forming galaxies when they collide with interstellar gas.
