A future very-high-energy view of our Galaxy

TL;DR

This paper models the population of very-high-energy gamma-ray sources in the inner Galaxy and predicts that future sensitive telescopes could vastly improve our understanding of these sources and related astrophysical phenomena.

Contribution

It presents a population model of gamma-ray sources and forecasts the detection capabilities of future gamma-ray observatories like CTA and AGIS.

Findings

Future telescopes could detect many more gamma-ray sources.

Improved resolution will enhance understanding of source populations.

Deep surveys will aid studies of diffuse gamma-ray emission and cosmic-ray interactions.

Abstract

The survey of the inner Galaxy with H.E.S.S. was remarkably successful in detecting a wide range of new very-high-energy gamma-ray sources. New TeV gamma-ray emitting source classes were established, although several of the sources remain unidentified, and progress has been made in understanding particle acceleration in astrophysical sources. In this work, we constructed a model of a population of such very-high-energy gamma-ray emitters and normalised the flux and size distribution of this population model to the H.E.S.S.-discovered sources. Extrapolating that population of objects to lower flux levels we investigate what a future array of imaging atmospheric telescopes (IACTs) such as AGIS or CTA might detect in a survey of the Inner Galaxy with an order of magnitude improvement in sensitivity. The sheer number of sources detected together with the improved resolving power will likely result in a huge improvement in our understanding of the populations of galactic gamma-ray sources. A deep survey of the inner Milky Way would also support studies of the interstellar diffuse gamma-ray emission in regions of high cosmic-ray density. In the final section of this paper we investigate the science potential for the Galactic Centre region for studying energy-dependent diffusion with such a future array.