A team of four astrophysicists from the Black Holes Group at the University of São Paulo (USP) built a gamma-ray sky map. They claim to be the sharpest ever produced.
Gamma radiation or gamma ray is a type of high frequency electromagnetic radiation usually produced by radioactive elements, subatomic processes such as the annihilation of a pair of positron and electron. This type of very energetic radiation is also produced in astrophysical phenomena of great importance.
“Gamma rays are the type of light with the highest energies that we can find in the universe”, explains Raniere Menezes, one of the scientists involved in the construction of this image, in an interview with the press office of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG ) of USP.
The work is led by Professor Rodrigo Nemmen, from IAG-USP, and was funded by FAPESP, the Coordination for the Improvement of Higher Education Personnel (Capes) and a Research Productivity grant from the National Council for Scientific and Technological Development (CNPq) .
For the construction of the map, another scientist of the group, Lucas Siconato, told the press office of the IAG-USP that “the group attributed the red color to the high-energy gamma radiation, the green color to the very high-energy gamma light, and blue for very high energy gamma light. For comparison purposes, the radiation that appears in this image has energy between 100 million and 1 trillion times that of visible light, and is invisible to human eyes”.
“This allows the image to really function as a map of the most energetic sources in the sky and gives us information about what kind of emissions we have in each one using colors that our eyes can distinguish,” said Douglas Carlos, staff member and fellow at Fapesp.
There are two important structures on the map: the first of them is the plane of our own galaxy, which appears in the central region of the image as a very bright horizontal band. The second is the Fermi bubbles, which are also seen in the central region of the image, projecting above and below the plane of the Milky Way. They are visually characterized by a bluish color and are associated with some recent activity by Sagittarius A*, the supermassive black hole located at the center of our Galaxy.
To build this map, astrophysicists used observations from NASA’s Fermi Space Telescope. The telescope began operations on June 11, 2008 and continues to function, monitoring the sky at high energy.