Study of Particle Acceleration in a Star Forming Region

Star forming regions (SFRs) have been postulated as possible sources of cosmic rays in our galaxy. One example of a gamma-ray source associated with an SFR is the Fermi-LAT cocoon, an extended region of gamma-ray emission detected by Fermi-LAT in the Cygnus X region and attributed to a cocoon of freshly accelerated cosmic rays (CRs). CRs in the cocoon could have originated in the OB2 association and been accelerated at the interaction sites of stellar winds of massive O type stars. Hence, in that case, the Fermi-LAT cocoon is a superbubble. So far, this cocoon has been only detected at GeV energies. The HAWC observatory has detected a TeV gamma-ray source 2HWC J2031+415 co-located with the cocoon. Spectral and morphological studies of the region with HAWC and Fermi-LAT data reveal the HAWC source as a likely counterpart of the cocoon. The spectral energy distribution of the cocoon extends from GeV to TeV. Using HAWC data, we are able to study the acceleration of particles to highest energies in the Cygnus OB2 SFR.