The Second Catalog of Low-Energy Fermi-LAT Sources
Abstract
We used 14 years of Fermi-Large Area Telescope (LAT) data to derive a catalog of sources detected between 20 MeV and 200 MeV. For each source we provide localization, spectral, and association information. The Second Catalog of Low-Energy Fermi-LAT sources (2FLE) contains 450 sources detected at TS>25, with median energy flux of F20−200 MeV = 1.9×10−11 erg cm−2 s−1. Using a Bayesian and likelihood-ratio method, we associate 377 2FLE sources with a known counterpart. Of the 325 objects associated with extragalactic sources, the dominant source class represented in the 2FLE are flat-spectrum radio quasars (FSRQ). Additionally, 52 sources are associated with Galactic sources. Three associated sources have not been previously detected in any γ-ray catalog and represent new γ-ray sources of known origin. We find that 387 2FLE sources have a positional cross-match with the 4FGL-DR4 sources. For the sources with a 4FGL counterpart, we compare the spectrum of the 2FLE source to the 4FGL spectral energy distributions. Of the 73 2FLE sources without multi-wavelength associations, 13 have a 4FGL counterpart that lacks classification, while 60 are newly discovered γ-ray sources. Among these 60 sources, 51 are found at high latitudes (|b|>10∘), and 38 are detected at >10σ. Additionally, we find that out of the 450 2FLE sources 45 are TeV emitters, and 6 are spatially coincident with a 1LHAASO source. The 2FLE helps us pave the way for reducing the ``MeV gap", and provides the most sensitive catalog between 20-200 MeV to date.
Related
- Identifying potentially missed extended sources in the Fermi-LAT 4FGL Catalog using clustering analysis
- 4FHL: The Fourth Catalog of Hard 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{adelfio2026second,
title = {{The Second Catalog of Low-Energy Fermi-LAT Sources}},
author = {A Adelfio and M Ajello and E Aviano and L Baldini and J Ballet and C Bartolini and D Bastieri and J. Becerra Gonzalez and R Bellazzini and E Bissaldi and R.D Blandford 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 N Cibrario and S Ciprini and O Coban 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 Domínguez and J Eagle and C Fernandez-Suarez and E.C Ferrara and A Fiori and A Franckowiak 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 I.A Grenier and S Guiriec and R Gupta and M Hashizume and E Hays and J.W Hewitt and A. Holzmann Airasca},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.18972},
eprint = {2610.18972},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05843901v1},
}
RIS
TY - UNPB
TI - The Second Catalog of Low-Energy Fermi-LAT Sources
AU - A Adelfio
AU - M Ajello
AU - E Aviano
AU - L Baldini
AU - J Ballet
AU - C Bartolini
AU - D Bastieri
AU - J. Becerra Gonzalez
AU - R Bellazzini
AU - E Bissaldi
AU - R.D Blandford
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 - N Cibrario
AU - S Ciprini
AU - O Coban
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 Domínguez
AU - J Eagle
AU - C Fernandez-Suarez
AU - E.C Ferrara
AU - A Fiori
AU - A Franckowiak
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 - I.A Grenier
AU - S Guiriec
AU - R Gupta
AU - M Hashizume
AU - E Hays
AU - J.W Hewitt
AU - A. Holzmann Airasca
PY - 2026
DA - 2026/10/13
PB - HAL
DO - 10.48550/arxiv.2610.18972
UR - https://hal.science/hal-05843901v1
AB - We used 14 years of Fermi-Large Area Telescope (LAT) data to derive a catalog of sources detected between 20 MeV and 200 MeV. For each source we provide localization, spectral, and association information. The Second Catalog of Low-Energy Fermi-LAT sources (2FLE) contains 450 sources detected at TS>25, with median energy flux of F_20−200 MeV = 1.9×10^−11 erg cm^−2 s^−1. Using a Bayesian and likelihood-ratio method, we associate 377 2FLE sources with a known counterpart. Of the 325 objects associated with extragalactic sources, the dominant source class represented in the 2FLE are flat-spectrum radio quasars (FSRQ). Additionally, 52 sources are associated with Galactic sources. Three associated sources have not been previously detected in any γ-ray catalog and represent new γ-ray sources of known origin. We find that 387 2FLE sources have a positional cross-match with the 4FGL-DR4 sources. For the sources with a 4FGL counterpart, we compare the spectrum of the 2FLE source to the 4FGL spectral energy distributions. Of the 73 2FLE sources without multi-wavelength associations, 13 have a 4FGL counterpart that lacks classification, while 60 are newly discovered γ-ray sources. Among these 60 sources, 51 are found at high latitudes (|b|>10^∘), and 38 are detected at >10σ. Additionally, we find that out of the 450 2FLE sources 45 are TeV emitters, and 6 are spatially coincident with a 1LHAASO source. The 2FLE helps us pave the way for reducing the ``MeV gap", and provides the most sensitive catalog between 20-200 MeV to date.
ER -