Nonthermal THz to TeV Emission from Stellar Wind Shocks in the Galactic Center

Abstract

The central parsec of the Galaxy contains dozens of massive stars with a cumulative mass-loss rate of ~10 -3 M solar yr -1. Shocks among these stellar winds produce the hot plasma that pervades the central part of the Galaxy. We argue that these stellar wind shocks also efficiently accelerate electrons and protons to relativistic energies. The relativistic electrons inverse Compton scatter the ambient ultraviolet and far-infrared radiation field, producing high-energy gamma-rays with a roughly constant luminosity from ~GeV to ~10 TeV. This can account for the TeV source seen by HESS in the Galactic center. Our model predicts a GLAST counterpart to the HESS source with a luminosity of ~10 35 ergs s -1 and cooling break at ~4 GeV. Synchrotron radiation from the same relativistic electrons should produce detectable emission at lower energies, with a surface brightness of ~10 -14 B 2 -3 ergs s -1 cm -2 arcsec -2 from ~THz to ~keV, where B -3 is the magnetic field strength in units of mG. The observed level of diffuse thermal X-ray emission in the central parsec requires B