Search for High-Energy Gamma Rays in the Northern Fermi Bubble Region with the HAWC Observatory

Abstract

Gamma-ray astronomy is the study of very energetic photons, from $E = m_e c^2 = 0.5$x$10^6$ eV to $> 10^{20}$eV. Due to the large span of the energy range, the field focuses on non-thermal processes that include the acceleration and propagation of relativistic particles, which can be found in extreme environments such as pulsars, supernova remnants, molecular clouds, black holes, etc.
The High Altitude Water Cherenkov (HAWC) observatory is an instrument designed for the study of gamma rays in the energy range of 100 GeV to 100 TeV. Using data from the HAWC observatory, a study for the search of very high energy gamma rays in the northern Fermi Bubble region was made. The Fermi Bubbles are large extended regions in the gamma-ray sky located above and below the galactic plane that present a hard emission between 1 GeV and 100 GeV. No significant excess is found an upper bounds at 95% C.L. are obtained. The implications of this result are that certain processes explaining the Fermi Bubble formation from the center of our galaxy are excluded. I will discuss and compare the scenarios that still present a possible hypothesis of the Fermi Bubble origin.