The Making of Catalogues of Very-High-Energy {\gamma}-ray Sources

TL;DR

This paper reviews the evolution of very-high-energy gamma-ray source catalogues, highlighting technological advances, data challenges, and the potential for future population studies with upcoming instruments.

Contribution

It summarizes the development of gamma-ray source catalogues, the impact of technological improvements, and discusses future prospects in the context of new-generation instruments.

Findings

Large catalogues enable population studies.

Technological advances improved sensitivity and resolution.

Future instruments will handle even larger datasets.

Abstract

Thirty years after the discovery of the first very-high-energy {\gamma}-ray source by the Whipple telescope, the field experienced a revolution mainly driven by the third generation of imaging atmospheric Cherenkov telescopes (IACTs). The combined use of large mirrors and the invention of the imaging technique at the Whipple telescope, stereoscopic observations, developed by the HEGRA array and the fine-grained camera, pioneered by the CAT telescope, led to a jump by a factor of more than ten in sensitivity. The advent of advanced analysis techniques led to a vast improvement in background rejection, as well as in angular and energy resolutions. Recent instruments already have to deal with a very large amount of data (petabytes), containing a large number of sources often very extended (at least within the Galactic plane) and overlapping each other, and the situation will become even more dramatic with future instruments. The first large catalogues of sources have emerged during the last decade, which required numerous, dedicated observations and developments, but also made the first population studies possible. This paper is an attempt to summarize the evolution of the field towards the building up of the source catalogues, to describe the first population studies already made possible, and to give some perspectives in the context of the upcoming, new generation of instruments.