This observatory monitors cosmic rays and gamma rays to detect a giant gamma ray bubble in a star forming region Swan OB2It is located approximately 4700 light years from Earth.

The gamma bubble contained many photons with energies above 1 PeV (pete-electron volts, 10 to the power of 15 eV), with a peak at 2.5 PeV. This showed that there was a natural particle accelerator inside the structure that gave them tremendous energy. The power of this accelerator was enough to accelerate the particles up to 20 PeV and throw them out of the balloon.

According to scientists, the most likely source of particle acceleration is the young and hot O and B type stars at the center of Cygnus OB2. The intensity of gamma radiation from these stars is so high that it expels protons from the surrounding interstellar gas, thus accelerating them.

Why is this an important discovery?

The Chinese team’s observation is the first time that such high-energy cosmic rays are associated with an astrophysical object or event in our galaxy. While cosmic rays with energies below 1 PeV are believed to originate from the galaxy, the source of rays with energies above 10 PeV is unknown.

The LHAASO observatory will continue to observe this and other star-forming regions to learn more about the observed processes.