The High Energy Stereoscopic System telescopes, found in Namibia, measure high-energy gamma rays as they're absorbed by Earth's atmosphere. New research suggests the center of the Milky Way is home to the most intense gamma-ray activity in the galaxy. Photo by H.E.S.S., MPIK/Christian Foehr
July 18 (UPI) -- According to the latest observations from several large gamma-ray telescopes, the center of the Milky Way contains a high-energy trap, where cosmic rays are slowed by clouds of gas and dust.
"Our results suggest that most of the cosmic rays populating the innermost region of our galaxy, and especially the most energetic ones, are produced in active regions beyond the galactic center and later slowed there through interactions with gas clouds," Daniele Gaggero, an astronomer at the University of Amsterdam, said in a news release.
Tracing the paths of cosmic rays is nearly impossible. But when they interact with matter, like a gas cloud in the middle of the Milky Way, the matter gets excited and emits gamma rays, which can be observed by NASA's Fermi Gamma-ray Space Telescope and the High Energy Stereoscopic System, an observatory in Namibia.
Fermi and H.E.S.S. observe gamma rays in different ways. Fermi observes gamma rays from space as they hit the observatory's Large Area Telescope. H.E.S.S. observes gamma rays as they're absorbed by Earth's atmosphere, triggering an intense blue light.
When astronomers calibrated the latest observations of the two telescopes, they found the data was largely in agreement. Both revealed a region of intense gamma-ray activity in the center of the galaxy.
"Once we subtracted bright point sources, we found good agreement between the LAT and H.E.S.S. data, which was somewhat surprising due to the different energy windows and observing techniques used," said Marco Taoso, researcher at the Institute of Theoretical Physics in Madrid.
The cosmic rays traveling through the center of the galaxy are the same cosmic rays moving through other parts of the Milky Way, but their path through the galactic center is much less efficient. As result, the region yields intense gamma ray emissions -- a glow boasting the highest energies yet observed by H.E.S.S.
Researchers hope the latest observations -- detailed this week in the journal Physical Review Letters -- will help astronomers locate and study neutrinos, another high-energy but less understood particle.
"The same breakneck particle collisions responsible for producing these gamma rays should also produce neutrinos, the fastest, lightest and least understood fundamental particles," said Antonio Marinelli, a researcher at Italy's National Institute of Nuclear Physics in Pisa.