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This paper explores the application of machine learning methods for classifying astronomical sources using photometric data, including normal and emission line galaxies (ELGs; starforming, starburst, AGN, broad line), quasars, and stars. We…

We present an incremental version (4FGL-DR4, for Data Release 4) of the fourth Fermi-LAT catalog containing 7194 gamma-ray sources. Based on the first 14 years of science data in the energy range from 50 MeV to 1 TeV, it uses the same…

High Energy Astrophysical Phenomena · Physics 2024-07-25 J. Ballet , P. Bruel , T. H. Burnett , B. Lott , The Fermi-LAT collaboration

The Fermi Gamma-ray Space Telescope has been detecting a wealth of sources where the multi-wavelength counterpart is either inconclusive or missing altogether. We present a combination of factors that can be used to identify…

High Energy Astrophysical Phenomena · Physics 2015-06-17 F. Acero , D. Donato , R. Ojha , J. Stevens , P. G. Edwards , E. Ferrara , J. Blanchard , J. E. J. Lovell , D. J. Thompson

The Fermi Large Area Telescope (LAT) has detected more than 5000 gamma-ray sources in its first 8 years of operation. More than 3000 of them are blazars. About 60 per cent of the Fermi-LAT blazars are classified as BL Lacertae objects (BL…

High Energy Astrophysical Phenomena · Physics 2020-06-22 Miloš Kovačević , Graziano Chiaro , Sara Cutini , Gino Tosti

We used a supervised machine learning algorithm (probabilistic random forest) to classify ~130 million sources in the VISTA Survey of the Magellanic Clouds (VMC). We used multi-wavelength photometry from optical to far-infrared as features…

We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of…

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

The Large Area Telescope (LAT) aboard the Fermi satellite allows us to study the high-energy gamma-ray sky with unprecedented sensitivity. However, the origin of 31% of the detected gamma-ray sources remains unknown. This population of…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Hannes-S. Zechlin , Dieter Horns

About a third of the $\gamma$-ray sources detected by the Fermi Large Area Telescope (Fermi-LAT) remain unidentified, and some of these could be exotic objects such as dark matter subhalos. We present a search for these sources using…

High Energy Astrophysical Phenomena · Physics 2023-08-02 Anja Butter , Michael Krämer , Silvia Manconi , Kathrin Nippel

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

We are starting a project to find $\gamma$-ray millisecond pulsars (MSPs) among the unidentified sources detected by the Large Area Telescope (LAT) onboard the {Fermi Gamma-Ray Space Telescope (Fermi)}, by radio observations. The selection…

High Energy Astrophysical Phenomena · Physics 2019-03-04 Xuejie Dai , Zhongxiang Wang , Jithesh Vadakkumthani

With assistance of the identified/associated sources in the second Fermi Large Area Telescope (LAT) catalog, we analyze and resolve the spatial distribution and the distributions of the gamma-ray spectral and variability indices of the…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Zhu Mao , Yun-Wei Yu

The determination of distance is fundamental in astrophysics. Gamma-ray sources are poorly characterized in this sense, as the limited angular resolution and poor photon-count statistics in gamma-ray astronomy makes it difficult to…

High Energy Astrophysical Phenomena · Physics 2023-04-03 Javier Coronado-Blázquez

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 4FGL-DR4 point-source catalog of the Large Area Telescope (LAT) onboard NASA's Fermi Gamma-ray Observatory (Fermi-LAT), around a third of the sources are still unidentified (unIDs). In this work, we perform a detailed study of one of…

We present the first Fermi Large Area Telescope (LAT) low energy catalog (1FLE) of sources detected in the energy range 30 - 100 MeV. The COMPTEL telescope detected sources below 30 MeV, while catalogs released by the Fermi-LAT and EGRET…

High Energy Astrophysical Phenomena · Physics 2018-10-10 Giacomo Principe , Dmitry Malyshev , Jean Ballet , Stefan Funk

The Fermi-LAT has detected more than 3000 sources in the GeV $\gamma$-ray regime. The majority are extra-galactic and these sources are dominated by blazars. However, $\sim28$ per cent of the sources in Fermi 3LAC are listed as blazar…

High Energy Astrophysical Phenomena · Physics 2017-02-01 L. Klindt , B. van Soelen , P. J. Meintjes , P. Väisänen

The first three months of sky-survey operation with the Fermi Gamma Ray Space Telescope (Fermi) Large Area Telescope (LAT) reveals 132 bright sources at |b|>10 deg with test statistic greater than 100 (corresponding to about 10 sigma). Two…

High Energy Astrophysical Phenomena · Physics 2009-09-30 A. A. Abdo

The Fermi/LAT telescope is an efficient blazar-detector in the MeV/GeV range. More than 1100 (900) blazars detected above 100 MeV (10 GeV) are clearly associated to BL Lacertae or Flat Spectrum Radio Quasar objects in the Fermi/LAT 3FGL…

High Energy Astrophysical Phenomena · Physics 2017-10-02 Julien Lefaucheur , Catherine Boisson , Paolo Goldoni , Santiago Pita

A significant fraction of all $\gamma$-ray sources detected by the Large Area Telescope aboard the \fer\ satellite is still lacking a low-energy counterpart. In addition, there is still a large population of $\gamma$-ray sources with…