After a massive wave of gamma rays struck Earth back in April 2015, scientists have declared that the gamma ray emission source was found by VERITAS in a distant galaxy named PKS 1441+25.
What is special about these emissions, apart from their massive number, is their advanced age, traveling for about half the age of the universe until they finally reached us, over 7.6 billion years. Their origination point was discerned through the use of the Very Energetic Radiation Imaging Telescope Array System, VERITAS, in US Arizona.
Gamma rays consist of high energy photons that give a high frequency of electromagnetic radiation. This type of radiation is the highest form of energy light existing in our universe and was discovered in 1900 by French physicist Paul Villard. The name which it currently possesses was given by Ernest Rutherford, the father of nuclear physics, in 1903.
The galaxy from which the gamma radiations came, PKS 1441+25 is an extremely rare type of galaxy, called a blazar. It has a supermassive black hole at its center, surrounded by a massive hot disc comprised of space dust and gas.
In its rapid orbit around the black hole, the disc sometimes creates twin jets of radiation that propel energy at the speed of light in various directions. Scientists were lucky that one of these jets was aimed directly at our planet, giving us detailed information about the galaxy as well as its core.
What is strange about these so-called jets is the reason why they experience this burst of gamma rays. Up to this point, several theories have been crafted in order to explain the phenomenon which causes these bursts to exist. The most prevalent of theories tells that inside these jets, several packets of hot gas are formed. When two of these packets collide, they give birth to this wave that gets propelled outward at the speed of light.
The jet aimed at our planet is located at a rather long distance from the galaxy’s core, nearly one-tenth of a light year away from the central black hole, with its emission area being over 5 light years away. Even more, the jet in question is uncommonly large when compared to its counterparts, measuring at over one-third of a light-year in diameter. Even though in the cosmic plane, one light year is relatively small in size, for us the area is staggering, ranging at 6 trillion miles.
The discovery aided by VERITAS shines a light on EBL as well. EBL is the extragalactic background light which illuminates space, giving us the capability to theoretically track the history of the universe. This background light is created by the countless stars and galaxies forming the night sky and can sometimes be described as a sort of fog that filters radiations in their travels. There has to be a perfect balance between EBL and the strength of the radiation itself in order for us to be able to study it.
Taking into account the fact that the gamma ray emission source was found by VERITAS, our view of the universe has gained another point of interest: finding the exact phenomenon which causes these massive bursts of energy. The more we know about the universe and its constant evolution, the more the universe continues to surprise us. Every answered question raises more and more questions alongside it as time goes by.