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Associating gamma-ray sources to their low-energy counterparts is one of the major challenges of modern gamma-ray astronomy. In the context of the Fourth Fermi Large Area Telescope Source Catalog (4FGL), the associations rely mainly on…

High Energy Astrophysical Phenomena · Physics 2020-06-03 Raniere de Menezes , Raffaele D'Abrusco , Francesco Massaro , Dario Gasparrini , Rodrigo Nemmen

We report on a search for steep spectrum radio sources within the 95% confidence error ellipses of the Fermi unassociated sources from the Large Array Telescope (LAT). Using existing catalogs and the newly released GMRT all-sky survey at…

High Energy Astrophysical Phenomena · Physics 2016-07-27 D. A. Frail , K. P. Mooley , P. Jagannathan , H. T. Intema

We present the results of our analysis devoted to the research of sources emitting in the energy bands surveyed by both the Swift-BAT and the Fermi-LAT telescopes. We cross-correlate the Fermi-LAT 1-year point source catalogue (1FGL) of…

High Energy Astrophysical Phenomena · Physics 2015-05-27 A. Maselli , G. Cusumano , E. Massaro , A. Segreto , V. La Parola , A. Tramacere , I. Donnarumma

The third Fermi-LAT catalog (3FGL) presented the data of the first four years of observations from the Fermi Gamma-ray Space Telescope mission. There are 3034 sources, 1010 of which still remain unidentified. Identifying and classifying…

Since 2008 August the Fermi Large Area Telescope (LAT) has provided continuous coverage of the gamma-ray sky yielding more than 5000 gamma-ray sources, but 54% of the detected sources remain with no certain or unknown association with a low…

High Energy Astrophysical Phenomena · Physics 2020-12-01 Chiaro G. , Kovacevic M. , La Mura G

We report on the results of deep X-ray follow-up observations of four unidentified Fermi/LAT gamma-ray sources at high Galactic latitudes using Suzaku. The studied objects were detected with high significance during the first 3 months of…

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

We describe an image-based method that uses two radio criteria, compactness and spectral index, to identify promising pulsar candidates among Fermi Large Area Telescope (LAT) unassociated sources. These criteria are applied to those radio…

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

About one third of the 3033 $\gamma$-ray sources in the Third Fermi-LAT Gamma-ray Source Catalogue (3FGL) are unidentified and do not have even a tentative association with a known object, hence they are defined as unassociated. Among…

High Energy Astrophysical Phenomena · Physics 2017-06-28 D. Salvetti , R. P. Mignani , A. De Luca , M. Marelli , C. Pallanca , A. A. Breeveld , P. Husemann , A. Belfiore , W. Becker , J. Greiner

In the latest data release from the Fermi $\gamma$-ray Space Telescope (the 4th Fermi LAT 14 yr Catalog, or 4FGL), more than 50% of the Galactic sources are yet to be identified. We observed 13 unidentified Fermi LAT sources with the…

High Energy Astrophysical Phenomena · Physics 2024-08-30 Blagoy Rangelov , Hui Yang , Brice Williams , Oleg Kargaltsev , Jeremy Hare , Kean Martinic

The first Fermi Large Area Telescope (LAT) catalogue of sources (1FHL) emitting at high energies (above 10 GeV) reports the details of 514 objects detected in the first three years of the Fermi mission. Of these, 71 were reported as…

High Energy Astrophysical Phenomena · Physics 2015-06-24 R. Landi , L. Bassani , J. B. Stephen , N. Masetti , A. Malizia , P. Ubertini

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

In the recently published 3FGL catalogue, the Fermi/LAT collaboration reports the detection of $\gamma$-ray emission from 3034 sources obtained after four years of observations. The nature of 1010 of those sources is unknown, whereas 2023…

High Energy Astrophysical Phenomena · Physics 2017-06-21 J. Lefaucheur , S. Pita

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

Context. Based on their overwhelming dominance among associated Fermi gamma ray catalogue sources, it is expected that a large fraction of the unidentified Fermi objects are blazars. Through crossmatching between the positions of…

We present an incremental version (4FGL-DR2, for Data Release 2) of the fourth Fermi-LAT catalog of gamma-ray sources. Based on the first ten years of science data in the energy range from 50 MeV to 1 TeV, it uses the same analysis methods…

High Energy Astrophysical Phenomena · Physics 2020-12-18 J. Ballet , T. H. Burnett , S. W. Digel , B. Lott

The Fermi Gamma-ray Space Telescope is producing the most detailed inventory of the gamma-ray sky to date. Despite tremendous achievements approximately 25% of all Fermi extragalactic sources in the Second Fermi LAT Catalogue (2FGL) are…

High Energy Astrophysical Phenomena · Physics 2012-12-12 T. Hassan , N. Mirabal , J. L. Contreras , I. Oya

The latest source catalog of the Fermi-LAT telescope contains more than 7000 $\gamma$-ray sources at GeV energies, with the two dominant source classes thought to be blazars and rotation-powered pulsars. Our target is the identification of…

High Energy Astrophysical Phenomena · Physics 2024-02-09 Martin G. F. Mayer , Werner Becker

The Fermi-LAT DR1 and DR2 4FGL catalogues feature more than 5000 gamma-ray sources of which about one fourth are not associated with already known objects, and approximately one third are associated with blazars of uncertain nature. We…

High Energy Astrophysical Phenomena · Physics 2021-06-30 S. Germani , G. Tosti , . Lubrano , S. Cutini , I. Mereu , A. Berretta