Speaker
Description
The Fermi Large Area Telescope (LAT) continuously surveys the gamma-ray sky since its launch in 2008. Through the years, the FHL catalog series has been produced, using the LAT data at the highest energies to characterize hard gamma-ray sources. The last published installment in this series is 3FHL, based on 7.5 years of data above 10 GeV and reporting the detection of 1556 hard gamma-ray sources.
In this contribution we present a novel catalog of hard Fermi-LAT sources, which will provide a comprehensive survey of the sky above 10 GeV using 16 years of LAT Pass8 data, corresponding to an improvement in statistics and sensitivity by a factor of 2, with respect to 3FHL. This catalog reports the detection and characterization of more than 2600 gamma-ray sources, several of which are extended. Each source has been characterized in the spectral, spatial and temporal domain, thus finding that almost 500 sources show signs of significant temporal variability on a year-long scale. The largest part of the detected sources is of extra-galactic origin ($\sim 85\%$), although several galatic sources are reported as well. Several sources do not appear in any previous LAT catalog and lack multi-wavelength counterparts, making them particularly compelling targets for future studies.
This catalog will provide a fundamental reference for present and future ground-based facilities active above a few 10 GeV, such as the Cherenkov Telescope Array Observatory (CTAO) and many others. It will also be a key resource for the design of future multi-wavelength and multi-messenger studies.