Exploring the nature of the galactic center γ-ray source with the Cherenkov telescope array

Abstract

Observations from multiple γ-ray telescopes have uncovered a high-energy γ-ray source spatially coincident with the Galactic center. Recently, a compelling model for the broadband γ-ray emission has been formulated, which posits that high-energy protons emanating from Sgr A* could produce γ-rays through π0 decays resulting from inelastic collisions with the traversed interstellar gas in the region. Models of the gas distribution in the Galactic center region imply that the resulting γ-ray morphology would be observed as a point source with all current telescopes, but that the upcoming Cherenkov Telescope Array (CTA) may be able to detect an extended emission profile with an unmistakable morphology. Here, we critically evaluate this claim, employing a three-dimensional gas distribution model and a detailed Monte Carlo simulation, and using the anticipated effective area and angular resolution of CTA. We find that the impressive angular resolution of CTA will be key to test hadronic emission models conclusively against, for example, point source or dark matter annihilation scenarios. We comment on the relevance of this result for searches for dark matter annihilation in the Galactic center region. © 2012. The American Astronomical Society. All rights reserved.