2019-01-24 20:58:51
The firmament that our ancestors observed is very different from the one we know today thanks to Science. Those barely managed to see a few thousand stars among which the Moon and various planets moved. Now, thanks to the knowledge of the laws that govern the Universe, together with the tremendous advances in instrumentation and astronomical observation, we know that beyond what is observable with the naked eye, the Cosmos harbors an immensity of bodies that, just a hundred years ago , the human being never came to imagine.
We know that the Sun is just one star among the hundreds of billions that exist in the Milky Way, a galaxy that houses, in addition to stars, a huge number of planets and satellites along with other extraordinary bodies, such as supernovae, stars of neutrons, pulsars, nebulae or black holes. Beyond, the Milky Way itself loses prominence among hundreds of billions of galaxies. And not content with that image, it has been possible to discover that, much more than what is seen, is what is guessed but escapes our vision, in the form of dark matter and dark energy.
Among all this enormous amount of objects, some stand out from the others with energy emissions of enormous magnitude. Our guest today in Talking to Scientists, Alberto Domínguez, a researcher from the High Energy Group of the Complutense University of Madrid, talks today about the most violent representatives of the Universe.
On June 11, 2008, the NASA launched the Fermi space telescope into orbit, designed to study gamma-ray sources and the physical processes that give rise to very large emissions of cosmic energy. During its more than 10 years of existence, Fermi has detected thousands of sources whose energy emission is due to the behavior of matter when subjected to extreme conditions. Under such conditions, matter releases radiation in the form of X and gamma rays, much more energetic than that released by bodies such as common stars, which owe their emission to their high temperature. Those are the violent phenomena, some of which take place in supernovae explosions, pulsar emissions, or when matter gathers and falls in the vicinity of a supermassive black hole.
Many of the sources detected by Fermi throughout his life of observation are called “blazars”. When a supermassive hole is surrounded by a huge disk of matter that is falling towards it, it emits a beam of particles in a direction perpendicular to the disk. If the released beam is pointed directly at Earth, it is known as a “blazar.” The Fermi space telescope was designed to detect the gamma photons generated by blazars, calculate their energy and position in the sky. This is how, with the data obtained during the years of observing him, the scientists of the Fermi-LAT, where Alberto Domínguez is Coordinator of the Group of Blazars and Galactic Nuclei, have prepared and published a series of maps that show the complete image of the sky at energies that were previously inaccessible. In 2015, an image (3FGL) was published that includes some 3,000 sources and at the moment, thanks to the improvements in data processing obtained by Fermi, a new image is being completed that will have twice as many sources as the previous one.
I invite you to listen to Alberto Domínguez, researcher of the High Energy Group of the Complutense University of Madrid and coordinator of the Group of Blazars and Galactic Nuclei.
References:
A new image of the Violent UniverseResearch and Science, March 2018.
NASA’s Fermi Space Telescope Sharpens its High-energy Vision
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