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Most of the $\gamma$-ray sources in the Fermi-LAT 14-year Source Catalogue are associated with pulsars and blazars. However, unveiling the nature of the still unassociated $\gamma$-ray sources is important for the understanding of high…

High Energy Astrophysical Phenomena · Physics 2024-07-10 M. E. Ortega , A. Petriella , S. Paron

We search for the presence of double gamma-ray line from unassociated Fermi-LAT sources including detailed Monte Carlo simulations to study its global statistical significance. Applying the Su & Finkbeiner selection criteria for high-energy…

High Energy Astrophysical Phenomena · Physics 2012-08-10 Andi Hektor , Martti Raidal , Elmo Tempel

AIMS. We are studying an unbiased sample of 42 nearby (z < 0.2) BL Lacertae objects with a multi-wavelength approach. The results of VLBI observations were presented in the first paper of this series. In this paper, we study the…

High Energy Astrophysical Phenomena · Physics 2018-11-08 F. D'Ammando , M. Giroletti , S. Rainò

The extragalactic gamma-ray sky is dominated by relativistic jets aligned to the observer's line of sight, i.e., blazars. A few of their misaligned counterparts, e.g., radio galaxies, are also detected with the Fermi-Large Area Telescope…

High Energy Astrophysical Phenomena · Physics 2024-10-15 Vaidehi S. Paliya , D. J. Saikia , Alberto Domínguez , C. S. Stalin

Blazars are a small fraction of all extragalactic sources but, unlike other objects, they are strong emitters across the entire electromagnetic spectrum. Recent data in the microwave region of the electromagnetic spectrum have become…

Cosmology and Nongalactic Astrophysics · Physics 2013-12-24 D. Gasparrini , E. Cavazzuti , P. Giommi , C. Pittori , S. Colafrancesco , Fermi-LAT collaboration

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

While supernova remnants (SNRs) are widely thought to be powerful cosmic-ray accelerators, indirect evidence comes from a small number of well-studied cases. Here we systematically determine the gamma-ray emission detected by the Fermi…

High Energy Astrophysical Phenomena · Physics 2015-07-14 F. de Palma , T. J. Brandt , J. W. Hewitt , G. Johannesson , L. Tibaldo

Active Galactic Nuclei (AGN) sources feature supermassive black holes that launch relativistic plasma jets. They are key $\gamma$-ray sources providing a unique laboratory for studying extreme particle acceleration and plasma physics.…

High Energy Astrophysical Phenomena · Physics 2026-02-03 Luana Passos-Reis , Elisabete M. de Gouveia Dal Pino , Tarek Hassan , Santiago Pita , Alberto Domínguez

We report on the results of X-ray and radio follow-up observations of two GeV gamma-ray sources 2FGL J0923.5+1508 and 2FGL J1502.1+5548, selected as candidates for high-redshift blazars from unassociated sources in the {\it Fermi} Large…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Y. Takahashi , J. Kataoka , K. Niinuma , M. Honma , Y. Inoue , T. Totani , S. Inoue , T. Nakamori , K. Maeda

Recent works have developed samples of blazars from among the Fermi-LAT unassociated sources via machine learning comparisons with known blazar samples. Continued analysis of these new blazars tests the predictions of the blazar sequence…

High Energy Astrophysical Phenomena · Physics 2023-07-17 Stephen Kerby , Abraham D. Falcone

Here we report the results of searching millisecond pulsar (MSP) candidates from the Fermi LAT second source catalog (2FGL). Seven unassociated $\gamma-$ray sources in this catalog are identified as promising MSP candidates based on their…

High Energy Astrophysical Phenomena · Physics 2015-08-19 C. Y. Hui , S. M. Park , C. P. Hu , L. C. C. Lin , K. L. Li , A. K. H. Kong , P. H. T. Tam , J. Takata , K. S. Cheng , Ruolan Jin , T. -C. Yen , Chunglee Kim

The Fermi All-sky Variability Analysis (FAVA) provides a photometric alternative for identifying week-long gamma-ray flares across the entire sky while being independent of any diffuse Galactic or isotropic emission model. We reviewed 779…

High Energy Astrophysical Phenomena · Physics 2024-02-29 Scott D. Joffre , Núria Torres-Albà , Marco Ajello , Daniel Kocevski , Rolf Buehler

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

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…

We report on the detection of a gamma-ray source at the position of the nearby star-forming galaxy (SFG) M83, which is found from our analysis of 14 years of the data obtained with the Large Area Telescope (LAT) on-board {\it Fermi…

High Energy Astrophysical Phenomena · Physics 2023-08-02 Yi Xing , Zhongxiang Wang

Observations by Fermi LAT enabled us to explore the population of non-recycled gamma-ray pulsars with the set of 89 objects. It was recently noted that there are apparent differences in properties of radio-quiet and radio-loud subsets. In…

High Energy Astrophysical Phenomena · Physics 2017-01-17 E. V. Sokolova , G. I. Rubtsov

Employing data collected during the first 25 months' observations by the Fermi-LAT, we describe and subsequently seek to model the very high energy (>300 MeV) emission from the central few parsecs of our Galaxy. We analyze the…

High Energy Astrophysical Phenomena · Physics 2011-09-08 M. Chernyakova , D. Malyshev , F. A. Aharonian , R. M. Crocker , D. I. Jones

We employ an efficient method for identifying gamma-ray sources across the entire sky, leveraging advanced algorithms from Fermi p y, and cleverly utilizing the Galactic diffuse background emission model to partition the entire sky into 72…

High Energy Astrophysical Phenomena · Physics 2024-12-30 Y. C. Xiang , P. Feng , X. F. Lan

In principle, the angular anisotropy in the extragalactic gamma-ray background (EGRB) places severe constraints upon putative populations of unresolved gamma-ray point sources. Existing estimates of the EGRB anisotropy have been constructed…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-02 Avery E. Broderick , Christoph Pfrommer , Ewald Puchwein , Philip Chang , Kendrick M. Smith

We use nine years of gamma-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves of more than two thousand active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different…

High Energy Astrophysical Phenomena · Physics 2020-07-01 P. Peñil , A. Domínguez , S. Buson , M. Ajello , J. Otero-Santos , J. A. Barrio , R. Nemmen , S. Cutini , B. Rani , A. Franckowiak , E. Cavazzuti