2FHL: The second Catalog of hard {\it Fermi}-LAT sources

TL;DR

This paper presents the second catalog of Fermi-LAT sources detected above 50 GeV, utilizing six years of data with improved detection methods to bridge the gap between ground-based and space-based gamma-ray observations.

Contribution

It introduces a new catalog of high-energy gamma-ray sources detected above 50 GeV using six years of Fermi-LAT data with enhanced analysis techniques.

Findings

Detection of numerous sources above 50 GeV.

Improved sensitivity and source characterization.

Bridges observational gap between space and ground-based gamma-ray telescopes.

Abstract

The {\it Fermi} Large Area Telescope (LAT) has been routinely gathering science data since August 2008, surveying the full sky every three hours. The first Fermi-LAT catalog of sources detected above 10 GeV (1FHL) relied on three years of data to characterize the $>$10 GeV sky. The improved acceptance and point-spread function of the new Pass 8 event reconstruction and classification together with six years of observations now available allow the detection and characterization of sources directly above 50 GeV. This closes the gap between ground-based Cherenkov telescopes, which have excellent sensitivity but small fields of view and short duty cycles, and all-sky observations at GeV energies from orbit. In this contribution we present the second catalog of hard Fermi-LAT sources detected at $>$50\,GeV.