Present and Future Gamma-Ray Probes of the Cygnus OB2 Environment

TL;DR

This paper analyzes gamma-ray emission mechanisms in the Cygnus OB2 region using recent MAGIC data, highlighting how spectral features can distinguish between pion decay and nuclear excitation models, and discusses implications for neutrino detection and future observations.

Contribution

It introduces a method to differentiate gamma-ray production mechanisms in stellar associations based on spectral features, incorporating recent observational data and future telescope prospects.

Findings

Both pion decay and nuclear excitation models fit the data.

A spectral bump from nuclear excitation can discriminate models.

Implications for neutrino detection and future gamma-ray observations.

Abstract

The MAGIC Collaboration has provided new observational data pertaining to the TeV J2032+4130 gamma-ray source (within the Cygnus OB2 region), for energies E_gamma >400 GeV. It is then appropriate to update the impact of these data on gamma-ray production mechanisms in stellar associations. We consider two mechanisms of gamma-ray emission, pion production and decay (PION) and photo-excitation of high-energy nuclei followed by prompt photo-emission from the daughter nuclei (A*). We find that while the data can be accommodated with either scenario, the A* features a spectral bump, corresponding to the threshold for exciting the Giant Dipole Resonance, which can serve to discriminate between them. We comment on neutrino emission and detection from the region if the PION and/or A* processes are operative. We also touch on the implications for this analysis of future Fermi and Cerenkov Telescope Array data.