VER J2019+407 and the Cygnus Cocoon

TL;DR

This paper investigates gamma-ray emissions from the Cygnus region, focusing on the gamma-Cygni supernova remnant and the Cygnus cocoon, using observations from Fermi and VERITAS to understand cosmic ray acceleration.

Contribution

It provides an analysis of the relationship between VER J2019+407, the gamma-Cygni SNR, and the Cygnus cocoon, including simulations for detecting cocoon emissions at very high energies.

Findings

Detection of gamma-ray emission associated with the Cygnus cocoon.

Simulations suggest prospects for observing cocoon at very high energies.

Analysis of how cocoon emission affects measurements of VER J2019+407.

Abstract

Current gamma-ray observatories have made substantial advances in the study of potential cosmic ray accelerators such as supernova remnants (SNRs), but the study of cosmic rays in flight from their parent accelerators remains a topic of great interest. The Fermi Gamma-ray Space Telescope (FGST) discovered a four square degree region of gamma-ray emission between 3 GeV and 100 GeV. This structure lies between the Cygnus OB2 association and the gamma-Cygni SNR, which is bright in gamma rays above 10 GeV. The atmospheric Cherenkov observatory VERITAS also sees VHE (> 100 GeV) gamma-ray emission from the direction gamma-Cygni (VER J2019+407). We discuss the relationship of VER J2019+407 to both the gamma-Cygni SNR and the cocoon. Toy model simulations are used to evaluate prospects for detecting the cocoon at very high energies with VERITAS, as well as ways in which cocoon emission at these energies could impact measurements of the morphology and spectrum of VER J2019+407.