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The fourth Fermi Large Area Telescope Source Catalog (4FGL) lists over 5000 gamma-ray sources with statistical significance above 4$\sigma$. About 23% of the sources listed in this catalog are unidentified/unassociated gamma-ray sources…

About one third of Fermi Large Area Telescope (LAT) sources are unassociated. We perform multi-class classification of Fermi-LAT sources using machine learning with the goal of probabilistic classification of the unassociated sources. A…

High Energy Astrophysical Phenomena · Physics 2025-03-07 Dmitry V. Malyshev

The Fermi Large Area Telescope First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of gamma-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of…

High Energy Astrophysical Phenomena · Physics 2015-05-30 LAT Collaboration

Nearly one-third of the sources in the $Fermi$-LAT catalogs lack a lower energy counterpart, hence being referred as unidentified/unassociated gamma-ray sources (UGSs). In order to firmly classify them, dedicated multifrequency follow-up…

A large fraction of Fermi-Large Area Telescope (LAT) sources in the fourth Fermi-LAT 14 yr catalog (4FGL) still remain unidentified (unIDed). We continued to improve our machine-learning pipeline and used it to classify 1206 X-ray sources…

High Energy Astrophysical Phenomena · Physics 2024-08-20 Hui Yang , Jeremy Hare , Oleg Kargaltsev

During its first four years of scientific observations, the Fermi Large Area Telescope (Fermi-LAT) detected 3033 $\gamma$-ray sources above a 4$\sigma$ significance level. Although most of the extra-Galactic sources are active galactic…

High Energy Astrophysical Phenomena · Physics 2019-08-15 G. La Mura , G. Chiaro , S. Ciroi , P. Rafanelli , D. Salvetti , M. Berton , V. Cracco

We have investigated a number of factors that can have significant impacts on the classification performance of $\gamma$-ray sources detected by Fermi Large Area Telescope (LAT) with machine learning techniques. We show that a framework of…

Instrumentation and Methods for Astrophysics · Physics 2020-01-29 Shengda Luo , Alex P. Leung , C. Y. Hui , K. L. Li

BL Lac Objects (BL Lacs) and Flat Spectrum Radio Quasars (FSRQs) are radio-loud active galaxies (AGNs) whose jets are seen at a small viewing angle (blazars), while Misaligned Active Galactic Nuclei (MAGNs) are mainly radiogalaxies of type…

High Energy Astrophysical Phenomena · Physics 2018-08-20 G. Chiaro , M. Meyer , N. Alvarez Crespo , R. J. Britto , J. P. Marais , B. van Soelen , D. Salvetti , G. La Mura , D. J Thompson

A significant fraction (~30%) of the high-energy gamma-ray sources listed in the second Fermi LAT catalog (2FGL) are still of unknown origin, being not yet associated with counterparts at low energies. We recently developed a new…

High Energy Astrophysical Phenomena · Physics 2015-06-15 F. Massaro , R. D'Abrusco , A. Paggi , N. Masetti , M. Giroletti , G. Tosti , Howard A. Smith , S. Funk

Machine learning algorithms have been used to determine probabilistic classifications of unassociated sources. Often classification into two large classes, such as Galactic and extra-galactic, is considered. However, there are many more…

High Energy Astrophysical Phenomena · Physics 2023-03-29 Dmitry Malyshev , Aakash Bhat

The Large Area Telescope (LAT) on board the \emph{Fermi} Gamma-ray Space Telescope has been continuously providing good quality survey data of the entire sky in the high energy range from 30 MeV to 500 GeV and above since August 2008. A…

High Energy Astrophysical Phenomena · Physics 2025-10-13 A. Pathania , K. K. Singh , S. K. Singh , A. Tolamatti , B. B. Singh , K. K. Yadav

The Third Catalog of Hard Fermi Large Area Telescope Sources (3FHL) reports the detection of 1556 objects at E > 10 GeV. However, 177 sources remain unassociated and 23 are associated with a ROSAT X-ray detection of unknown origin. Pointed…

High Energy Astrophysical Phenomena · Physics 2022-12-07 S. Joffre , R. Silver , M. Rajagopal , M. Ajello , N. Torres-Albà , A. Pizzetti , S. Marchesi , A. Kaur

The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The Second LAT AGN Catalog (2LAC) includes 1017 gamma-ray sources located at high…

High Energy Astrophysical Phenomena · Physics 2015-05-30 LAT Collaboration

The third Fermi source catalog lists 3033 gamma-ray sources above $4\sigma$ significance. More than 30% are classified as either unidentified/unassociated Gamma-ray sources (UGSs), with about 20% classified as Blazar candidates of uncertain…

Astrophysics of Galaxies · Physics 2019-03-26 Marchesini , E. J. , Peña-Herazo , H. A. , Álvarez Crespo , N. , Ricci , F. , M. Negro , Milisavljevic , D. , Massaro , F. , Masetti , N. , Landoni , M. , Chavushyan , V. , D'Abrusco , R. , Jiménez-Bailón , E. , La Franca , F. , Paggi , A. , Smith , H. A. , Tosti , G.

Blazars, one of the most extreme class of active galaxies, constitute so far the largest known population of $\gamma$-ray sources and their number is continuously growing in the Fermi catalogs. However in the latest release of the Fermi…

The use of Bayesian neural networks is a novel approach for the classification of gamma-ray sources. We focus on the classification of Fermi-LAT blazar candidates, which can be divided into BL Lacertae objects and Flat Spectrum Radio…

High Energy Astrophysical Phenomena · Physics 2022-05-13 Anja Butter , Thorben Finke , Felicitas Keil , Michael Krämer , Silvia Manconi

The study of machine learning (ML) techniques for the autonomous classification of astrophysical sources is of great interest, and we explore its applications in the context of a multifrequency data-frame. We test the use of supervised ML…

High Energy Astrophysical Phenomena · Physics 2020-10-07 Bruno Arsioli , Pedro Dedin

One of the main scientific objectives of the recent Fermi mission is investigating the origin of the unidentified gamma-ray sources (UGSs). Despite the large improvements of Fermi in the gamma-ray source localization with respect to the…

High Energy Astrophysical Phenomena · Physics 2013-03-15 F. Massaro , R. D'Abrusco , A. Paggi , N. Masetti , M. Giroletti , G. Tosti , Howard A. Smith

The Fermi Large Area Telescope (Fermi-LAT) 3FHL catalog is the latest catalog of >10 GeV sources and will remain an important resource for the high-energy community for the foreseeable future. Therefore, it is crucial that this catalog is…

High Energy Astrophysical Phenomena · Physics 2020-10-14 Ross Silver , Stefano Marchesi , Lea Marcotulli , Aman Kaur , Meenakshi Rajagopal , Marco Ajello

The third catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (3LAC) is presented. It is based on the third catalog (3FGL,\cite{3FGL}) of sources detected with a test statistic greater than 25, using the…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Dario Gasparrini , Benoit Lott , Sara Cutini , Stefano Ciprini , Elisabetta Cavazzuti