Periodic signals of very energetic light have been identified in eleven galaxies using the Gamma-ray Space Telescope Fermi-LAT NASA . This signal is repeated approximately every two years and its discovery paves the way for future studies of unconventional galaxies that may harbor two supermassive black holes inside. These results, from an international team led by researchers from the Complutense University of Madrid, have just been published in The Astrophysical Journal . It is a fact well known to astronomers that most galaxies have a supermassive black hole, with a mass of hundreds of millions of that of our Sun. A percentage of these black holes are in a state known as the active galactic nucleus, where they are swallowing all the material around them. As a consequence, jets of particles are emitted at speeds close to light out of the galaxy. “We have analyzed the light emitted by these jets, in particular the highest energy light known, also called gamma rays,” says Pablo Peñil, a PhD student in Astrophysics at Complutense and lead author of the article.
In this study, the gamma ray emissions of more than 2,000 active nucleus galaxies have been analyzed using nine years of data obtained by Fermi-LAT. The result of this analysis is the identification of a sample of eleven galaxies that have emissions that are repeated approximately every two years, nine of them unknown until now .
For this achievement, astrophysicists have developed automatic data analysis tools. “With the results of this work, new lines of research are opened,” says researcher Alberto Domínguez, co-author of the work. “We would like to understand what astrophysical phenomenon is causing this periodic behavior and for this we have to complement our observations from space with others using telescopes on Earth.”
There are several possibilities to explain the origin of this phenomenon, probably the most exciting is the existence of two supermassive black holes , instead of one, inside these active galaxies. “The image of two black holes orbiting analogously to how our Earth-Moon system does is very attractive, however, we have to continue taking data to confirm this idea,” adds Professor Juan Abel Barrio, also co-author of the Article. “There are other possible explanations that we will have to check, for example, that the jets of particles that characterize these galaxies have a precession movement similar to that of a spinning top,” he concluded.