Very-High-Energy Astrophysical Processes in the Cygnus Region of the Milky Way

Very-high-energy (VHE) gamma-ray astronomy can provide insight in to the origin of cosmic rays. The Cygnus arm of the Galaxy is a well studied region and has been shown to have active sources of particle acceleration. VERITAS (Very Energetic Radiation Imaging Telescope Array System) is an array of four 12 meter diameter imaging atmospheric Cherenkov telescopes located at the Fred Lawrence Whipple Observatory in southern Arizona. From 2007 through 2012 VERITAS observed the Cygnus region for nearly 300 hours from 67° to 82° in Galactic longitude and from -1° to 4° in Galactic latitude. The survey and followup observations detected four sources: VER J2031+415, VER J2019+407, VER J2016+317, and VER J2019+368. The Fermi Large Area Telescope (Fermi-LAT) is a satellite gamma-ray telescope operating in the high-energy gamma-ray regime. The emission detected by the Fermi-LAT can provide insight into the nature of these sources and guide targeted followup observations in the region. We have reanalyzed the VERITAS data with updated VERITAS analysis and completed an analysis of over seven years of Fermi-LAT data in the region. We have discovered Fermi-LAT emission associated with VER J2031+415 strengthening its interpretation as a pulsar wind nebula, the SNR nature of VER J2019+407 has been confirmed by this study, and VER J2016+317 has been confirmed to be associated with the pulsar wind nebula CTB 87 rather than with a blazar source located at the same position. The Cygnus region is observed to be a particularly bright region of the Galaxy with both very-high-energy and high-energy gamma-ray experiments. These results motivate continued study of the region with VERITAS, as well as with current and future experiments such as HAWC and CTA.