Search for a Very High-Energy Gamma-Ray Signal in the Northern Fermi Bubble Region with HAWC.

In 2010, two GeV gamma-ray lobes, known as the Fermi Bubbles, were discovered in the data from The Fermi Large Area Telescope. They extend up to 55° above and below the Galactic Center, forming two regions of spectrally hard gamma-ray emission. One of the ways to understand their origin is through studying the spectrum. The spectrum can be described by hadronic and leptonic models. However, how much each process contributes is uncertain. Recent publications show that the spectrum of the Fermi Bubbles is well described by a power law with an exponential cutoff between 100MeV to 500GeV. Observing the Fermi Bubbles at higher gamma-ray energies will help constrain their spectrum. A steeper spectral cut-off will favor a dominant contribution from inverse Compton scattering. The High Altitude Water Cherenkov (HAWC) Observatory, located 4100m above sea level in Mexico, is sensitive to highenergy gamma rays between 100GeV to 100TeV. With a large field of view and good sensitivity to spatially extended sources, HAWC is the ground-based observatory best suited to detect extended regions like the Fermi Bubbles. We present a search for emission from the Fermi Bubble region visible to HAWC. [ABSTRACT FROM AUTHOR]