A team of astronomers are beginning to unravel the mysteries of the universe after having made the best measurement of all the light in the universe since the Big Bang, according to a new study.
Astronomers from the University of California at Riverside have measured the elusive extragalactic background light (EBL). The EBL is the integrated flux from all extragalactic sources, including those which are individually detected. The researchers made the most accurate measurement of the extragalactic background light (EBL) by using observations spanning wavelengths from radio waves to very energetic gamma rays.
According to astronomers, the EBL is an extremely important measurement for scientists working to understand the expansion history of the universe, as well as the history of galaxy formation and evolution.
Directly measuring the EBL by collecting its photons with a telescope poses towering technical challenges. Earth sits in a very bright Solar System, which almost acts like light pollution when trying to make reliable EBL measurements.
"Five billion years ago is the maximum distance we are able to probe with our current technology," Alberto Dominguez, of the Department of Physics and Astronomy at the University of California, said in a statement. "Sure, there are blazars farther away, but we are not able to detect them because the high-energy gamma rays they are emitting are too attenuated by EBL when they get to us-so weakened that our instruments are not sensitive enough to detect them."
Astrophysicists had to measure the EBL through measuring the attenuation of very high energy gamma rays from distant blazars, which are supermassive black holes in the centers of galaxies with brilliant jets pointed towards Earth, the study noted.
Not all the high-energy gamma rays emitted by a blazar make it all the way across billions of light-years to Earth, because some of it strikes an EBL photon along the way. When this happens, both are annihilated and produce two different particles: an electron and a positron.
