4FHL: The Fourth Catalog of Hard Fermi-LAT Sources
Abstract
We present a catalog of sources detected above 50 GeV by the Fermi Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope using 16 years of observations. This is the Fourth Catalog of Hard Fermi-LAT Sources (4FHL), containing 673 objects detected in the 50 GeV-2 TeV energy range. The sensitivity and localization are improved by factors of ∼2 relative to the previous LAT catalog at the same energies (i.e. the 2FHL catalog). The increased photon statistics, nearly doubling the number of detections relative to 2FHL, enables more detailed population studies, including the identification of fainter sources detected above 50 GeV. The majority of the sources (84.7\%) are associated with extragalactic counterparts, primarily BL Lacertae objects, including 36 objects at redshift z>1. Galactic sources account for 10\% of the sample, mainly pulsar wind nebulae and supernova remnants, while ∼5\% remain unassociated or of uncertain classification. Twenty sources are reported with no counterpart in previous LAT catalogs. The 4FHL catalog provides the deepest all-sky survey above 50 GeV to date. By focusing on this high-energy regime, it provides a fundamental link between space-based gamma-ray observations and the TeV range probed by current and future ground-based observatories. It serves as a useful reference for guiding future observations, including new potential targets for follow-up with Cherenkov telescopes.
Related
- Identifying potentially missed extended sources in the Fermi-LAT 4FGL Catalog using clustering analysis
- The Second Catalog of Low-Energy Fermi-LAT Sources
- Hierarchical Bayesian Inference on the Intrinsic Event Rate of Type I Gamma-Ray Bursts from the Fermi/GBM Catalog
- Expanding the Population of Short Gamma-Ray Transients with a Coherent Fermi/GBM Search. A 13-year catalog of short GRBs
- Dark Matter Interpretations of the Galactic Center Gamma-Ray Excess with 18 Years of Fermi-LAT Data and the FL16Y Source Catalog
BibTeX
@misc{acero20264fhl,
title = {{4FHL: The Fourth Catalog of Hard Fermi-LAT Sources}},
author = {F Acero and A Adelio and M Ajello and E Aviano and L Baldini and J Ballet and C Bartolini and J. Becerrra Gonzalez and R Bellazzini and E Bissaldi and R Bonino and P Bruel and S Buson and R.A Cameron and S Capecchiacci and P.A Caraveo and F Casaburo and F Casini and E Cavazzuti and C.C Cheung and N Cibrario and S Ciprini and G Cozzolongo and P. Cristarella Orestano and F Cuna and A Cuoco and S Cutini and F d'Ammando and P de la Torre Luque and D Depalo and N Di Lalla and A Dinesh and L Di Venere and A Dominguez and J Eagle and S.D Feagan and Y Fukazawa and S Funk and P Fusco and F Gargano and S Garrappa and C Gasbarra and D Gasparrini and S Germani and F Giacchino and N Giglietto and M Giliberti and F Giordano and M Giroletti and S Guiriec and R Gupta and A Harding and M Hashizume and E Hays and A. Holzmann Airasca and D Horan and D Kocevski and M Kuss and D.A Langis and A Laviron},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.31457},
eprint = {2609.31457},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05782024v1},
}
RIS
TY - UNPB
TI - 4FHL: The Fourth Catalog of Hard Fermi-LAT Sources
AU - F Acero
AU - A Adelio
AU - M Ajello
AU - E Aviano
AU - L Baldini
AU - J Ballet
AU - C Bartolini
AU - J. Becerrra Gonzalez
AU - R Bellazzini
AU - E Bissaldi
AU - R Bonino
AU - P Bruel
AU - S Buson
AU - R.A Cameron
AU - S Capecchiacci
AU - P.A Caraveo
AU - F Casaburo
AU - F Casini
AU - E Cavazzuti
AU - C.C Cheung
AU - N Cibrario
AU - S Ciprini
AU - G Cozzolongo
AU - P. Cristarella Orestano
AU - F Cuna
AU - A Cuoco
AU - S Cutini
AU - F d'Ammando
AU - P de la Torre Luque
AU - D Depalo
AU - N Di Lalla
AU - A Dinesh
AU - L Di Venere
AU - A Dominguez
AU - J Eagle
AU - S.D Feagan
AU - Y Fukazawa
AU - S Funk
AU - P Fusco
AU - F Gargano
AU - S Garrappa
AU - C Gasbarra
AU - D Gasparrini
AU - S Germani
AU - F Giacchino
AU - N Giglietto
AU - M Giliberti
AU - F Giordano
AU - M Giroletti
AU - S Guiriec
AU - R Gupta
AU - A Harding
AU - M Hashizume
AU - E Hays
AU - A. Holzmann Airasca
AU - D Horan
AU - D Kocevski
AU - M Kuss
AU - D.A Langis
AU - A Laviron
PY - 2026
DA - 2026/09/25
PB - HAL
DO - 10.48550/arxiv.2609.31457
UR - https://hal.science/hal-05782024v1
AB - We present a catalog of sources detected above 50 GeV by the Fermi Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope using 16 years of observations. This is the Fourth Catalog of Hard Fermi-LAT Sources (4FHL), containing 673 objects detected in the 50 GeV-2 TeV energy range. The sensitivity and localization are improved by factors of ∼2 relative to the previous LAT catalog at the same energies (i.e. the 2FHL catalog). The increased photon statistics, nearly doubling the number of detections relative to 2FHL, enables more detailed population studies, including the identification of fainter sources detected above 50 GeV. The majority of the sources (84.7\%) are associated with extragalactic counterparts, primarily BL Lacertae objects, including 36 objects at redshift z>1. Galactic sources account for 10\% of the sample, mainly pulsar wind nebulae and supernova remnants, while ∼5\% remain unassociated or of uncertain classification. Twenty sources are reported with no counterpart in previous LAT catalogs. The 4FHL catalog provides the deepest all-sky survey above 50 GeV to date. By focusing on this high-energy regime, it provides a fundamental link between space-based gamma-ray observations and the TeV range probed by current and future ground-based observatories. It serves as a useful reference for guiding future observations, including new potential targets for follow-up with Cherenkov telescopes.
ER -