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In the paper we develop multi-class classification of Fermi-LAT gamma-ray sources using machine learning with hierarchical determination of classes. One of the main challenges in the multi-class classification of the Fermi-LAT sources is…

High Energy Astrophysical Phenomena · Physics 2023-07-14 Dmitry V. Malyshev , Aakash Bhat

We report our detailed data analysis for 39 $\gamma$-ray sources selected from the 992 unassociated sources in the \textit{Fermi} Large Area Telescope (LAT) third source catalog. The selection criteria, which were set for finding candidate…

High Energy Astrophysical Phenomena · Physics 2021-06-03 Xuejie Dai , Zhongxiang Wang , V. Jithesh , Yi Xing

In this work, we make use of a supervised machine learning algorithm based on Logistic Regression (LR) to select TeV blazar candidates from the 4FGL-DR2 / 4LAC-DR2, 3FHL, 3HSP, and 2BIGB catalogs. LR constructs a hyperplane based on a…

High Energy Astrophysical Phenomena · Physics 2023-06-28 J. T. Zhu , C. Lin , H. B. Xiao , J. H. Fan , D. Bastieri , G. G. Wang

We present a catalog of gamma-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first 3 years of the Fermi Gamma-ray Space Telescope mission. This catalog complements the Second…

High Energy Astrophysical Phenomena · Physics 2013-04-16 David Paneque , Jean Ballet , Toby Burnett , Seth Digel , Pascal Fortin , Juergen Knoedlseder

The Fermi-LAT collaboration has recently released a new point source catalog, referred to as 4FGL. For the first time, we perform a template fit using information from this new catalog and find that the Galactic center excess is still…

High Energy Astrophysical Phenomena · Physics 2020-07-01 Yi-Ming Zhong , Samuel D. McDermott , Ilias Cholis , Patrick J. Fox

We discuss a new method for unveiling the possible blazar AGN nature among the numerous population of Unassociated Gamma-ray sources (UGS) in the Fermi catalogues. Our tool relies on positional correspondence of the Fermi object with X-ray…

High Energy Astrophysical Phenomena · Physics 2017-05-31 Simona Paiano , Alberto Franceschini , Antonio Stamerra

The Second Fermi LAT source catalog (Nolan et al. 2012) includes as many as 1,873 sources, but initial attempts to identify counterparts at other wavelengths resulted in 575 sources remaining unidentified. The 2FGL catalog is based on the…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Masaki Nishimichi , Takeshi Okuda , Masaki Mori , Philip G. Edwards , Jamie Stevens

Building on our previous cross-correlation analysis (Xia et al. 2011) between the isotropic gamma-ray background (IGRB) and different tracers of the large-scale structure of the universe, we update our results using 60-months of data from…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-24 Jun-Qing Xia , Alessandro Cuoco , Enzo Branchini , Matteo Viel

We identified Active Galactic Nuclei (AGN) candidates as counterparts to unidentified gamma-ray sources (UGS) from the Fermi-LAT Fourth Source Catalogue at lower Galactic latitudes. Our methodology is based on the use of near- and…

Following our work presented in Dai et al. (2016), we report our detailed data analysis for another 38 Fermi gamma-ray un-associated sources. These sources are selected from the Fermi Large Area Telescope (LAT) third source catalog on the…

High Energy Astrophysical Phenomena · Physics 2021-06-03 Xuejie Dai , Zhongxiang Wang , V. Jithesh , Yi Xing

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

Searching for as yet undetected gamma-ray sources is a major target of the Fermi LAT Collaboration. We present an algorithm capable of identifying such type of sources by non-parametrically clustering the directions of arrival of the…

Instrumentation and Methods for Astrophysics · Physics 2023-01-30 Anna Montin , Alessandra R. Brazzale , Giovanna Menardi

One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of the unidentified gamma-ray sources (UGSs). Despite the large improvements of Fermi in the localization of gamma-ray sources with respect to the…

High Energy Astrophysical Phenomena · Physics 2015-06-04 F. Massaro , R. D'Abrusco , G. Tosti , M. Ajello , A. Paggi. D. Gasparrini

The fourth Fermi Large Area Telescope (LAT) catalog (4FGL) contains 5064 $\gamma$-ray sources detected at high significance, but 26% of them still lack associations at other wavelengths. The SPT-SZ survey, conducted between 2008 and 2011…

High Energy Astrophysical Phenomena · Physics 2023-01-04 Lizhong Zhang , Joaquin D. Vieira , Marco Ajello , Matthew A. Malkan , Melanie A. Archipley , Joseph Capota , Allen Foster , Greg Madejski

We search for dark matter (DM) annihilating subhalos of the Milky Way halo among the Fermi Large Area Telescope (LAT) unassociated sources. We construct, for the first time, a statistical model of the unassociated sources at latitudes above…

High Energy Astrophysical Phenomena · Physics 2025-03-20 Aurelio Amerio , Dmitry Malyshev , Bryan Zaldivar , Viviana Gammaldi , Miguel Ángel Sánchez-Conde

Approximately one-third of existing $\gamma$-ray sources identified by the $\textit{Fermi Gamma-Ray Space Telescope}$ are considered to be unassociated, with no known counterpart at other frequencies/wavelengths. These sources have been the…

High Energy Astrophysical Phenomena · Physics 2023-02-01 S. Bruzewski , F. K. Schinzel , G. B. Taylor

An excess of $\gamma$-ray emission from the Galactic Center (GC) region with respect to predictions based on a variety of interstellar emission models and $\gamma$-ray source catalogs has been found by many groups using data from the {\it…

High Energy Astrophysical Phenomena · Physics 2017-10-31 LAT Collaboration

Studying unidentified {\gamma}-ray sources is important as they may hide new discoveries. We conducted a multiwavelength analysis of 13 unidentified Fermi-LAT sources in the 3FGL catalog that have no known counterparts (Unidentified…

High Energy Astrophysical Phenomena · Physics 2021-07-14 Jean Damascène Mbarubucyeye , Felicia Krauß , Pheneas Nkundabakura

The sensitivity of the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope allows detection of thousands of new gamma-ray sources and detailed characterization of the spectra and variability of bright sources.…

Instrumentation and Methods for Astrophysics · Physics 2015-03-18 Matthew Kerr

Blazars are jet-dominated extragalactic objects characterized by the emission of strongly variable non-thermal radiation across the entire electromagnetic spectrum. Therefore, the study of blazars (and in general of radio loud AGN) through…

High Energy Astrophysical Phenomena · Physics 2019-08-15 C. Monte , S. Raino , F. Gargano , S. Cutini , D. Gasparrini , J. Leon Tavares , G. Polenta
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