Gamma Rays From Pulsars?

Most of the gamma rays scientists have observed in the past have been lower-energy gamma rays. But with the High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) in Mexico, which was completed a few years ago, physicists are now able to survey the entire sky for gamma rays with especially high energies. Physicists are confident that high-energy gamma rays are created in phenomena that involve cosmic rays, but for low-energy gamma rays, that’s not always the case.



The nine new gamma-ray sources found by the HAWC collaboration, which includes institutions in Mexico, the U.S., Europe and South America, make up the first catalog of gamma-ray sources in this high-energy range.



“These are actually the highest-energy gamma rays ever seen,” said Brenda Dingus, a physicist at Los Alamos National Laboratory and a senior member of the HAWC collaboration. Some of these gamma rays have about 10 times the energy of the most energetic gamma rays that have been created in particle accelerators on Earth.



Interestingly, the new high-energy gamma-ray sources are all located near pulsars — extremely magnetic rotating neutron stars that shoot jets of radiation through space. This makes the researchers wonder whether the high-energy gamma rays — and the cosmic rays that produced them — are a common feature of pulsars, says Kelly Malone, an LANL physicist and lead author of the new paper.



According to the researchers, once scientists upgrade the sensitivity of the HAWC observatory’s detector, they should start seeing even more of these high-energy gamma-ray sources, which will further help them pin down their origins.





Disclosure statement: Erika K. Carlson currently works part time for Physics magazine, which is published by the American Physical Society. The American Physical Society also publishes the journal Physical Review Letters, which published the new research discussed above.