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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…

The impact of the Fermi Gamma-ray Space Telescope on blazar research is reviewed. This includes a brief description of the Fermi Large Area Telescope, a summary of the various classes of extragalactic sources found in the First Large Area…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Charles D. Dermer

In the first 3.5 years of operations the Fermi LAT detected several sources with daily fluxes brighter than F(E>100MeV) > 10^{-6} ph/cm^2/s, the threshold set by the Fermi Collaboration for issuing an Astronomer Telegram. We focus the…

High Energy Astrophysical Phenomena · Physics 2013-03-13 S. Buson , D. Bastieri , F. D'Ammando , G. Tosti

The identification and classification of Fermi blazars are core topics in high-energy astrophysics. To enable precise spatial cross-identification, we constructed two high-precision catalogs: the updated 4FGL-Xiang-DR2 (DR2) and a…

High Energy Astrophysical Phenomena · Physics 2026-01-27 Yunchuan Xiang , Yingzhi Ye , Peng Feng , Huili , Xiankai Pang , Xiaofei Lan , Qingquan Jiang , Ningfeng Zhang

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 report on the analysis of 13 gamma-ray pulsars discovered in the Einstein@Home blind search survey using Fermi Large Area Telescope (LAT) Pass 8 data. The 13 new gamma-ray pulsars were discovered by searching 118 unassociated LAT sources…

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

We analyze the angular power spectrum (APS) of the unresolved gamma-ray background (UGRB) emission and combine it with the measured properties of the resolved gamma-ray sources of the Fermi-LAT 4FGL catalog. Our goals are to dissect the…

High Energy Astrophysical Phenomena · Physics 2023-07-07 Michael Korsmeier , Elena Pinetti , Michela Negro , Marco Regis , Nicolao Fornengo

We find evidence for large-scale clustering amongst Fermi-selected BL Lac objects but not amongst Fermi-selected FSRQs. Using two-point correlation functions we have investigated the clustering properties of different classes of objects…

High Energy Astrophysical Phenomena · Physics 2021-11-08 M. J. M. Marcha , I. W. A. Browne

Aims. We present a sample of 4388 AGNs with available radio core-dominance parameters defined as the ratio of the core flux densities to extended ones, namely, R = Score/Sext., which includes 630 Fermi-detected AGNs respect to the catalog…

Astrophysics of Galaxies · Physics 2019-05-14 Zhi-Yuan Pei , Jun-Hui Fan , Denis Bastieri , Jiang-He Yang , Hu-Bing Xiao

We utilized a sample from the Fermi-LAT 14-year Source Catalog by adjusting the flux detection threshold, enabling us to derive the intrinsic source count distribution $dN/dF_{25}$ of extragalactic blazars using nonparametric, unbinned…

High Energy Astrophysical Phenomena · Physics 2024-08-28 Xuhang Yin , Houdun Zeng

In the forthcoming era of big astronomical data, it is a burden to find out target sources from ground-based and space-based telescopes. Although Machine Learning (ML) methods have been extensively utilized to address this issue, the…

High Energy Astrophysical Phenomena · Physics 2024-01-08 Haitao Cao , Hubing Xiao , Zhijian Luo , Xiangtao Zeng , Junhui Fan

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 considered the fourth catalog of gamma-ray point sources produced by the Fermi Large Area Telescope (LAT) and selected only jetted active galactic nuclei (AGN) or sources with no specific classification, but with a low-frequency…

Context. Although Blazars are a small fraction of the overall AGN population they are expected to be the dominant population of extragalactic sources in the hard X-ray and gamma-ray bands and have been shown to be the largest contaminant of…

Astrophysics · Physics 2008-11-26 S. Turriziani , E. Cavazzuti , P. Giommi

Blazars dominate the extragalactic $\gamma$-ray sky and show pronounced flares. Using public Fermi-LAT light curves for 732 blazars with secure redshifts, I implement an automated pipeline to identify and characterize $\gamma$-ray bursts…

High Energy Astrophysical Phenomena · Physics 2025-08-29 Matteo Cerruti

The classification of gamma-ray-detected blazar candidates of uncertain type (BCU) is a relevant problem in extragalactic gamma-ray astronomy. Here we report the optical spectroscopic characterization, using two 3-4~m class telescopes,…

We study the $\gamma$-ray and broadband spectral energy distribution (SED) properties of a complete sample of 104 bright, radio-selected low-synchrotron peaked (LSP) blazars. Most of the sources have already been detected in the…

High Energy Astrophysical Phenomena · Physics 2018-08-08 B. Arsioli , G. Polenta

The extragalactic gamma-ray sky is dominated by the emission arising from blazars, one of the most peculiar classes of radio-loud active galaxies. Since the launch of Fermi several methods were developed to search for blazars as potential…

High Energy Astrophysical Phenomena · Physics 2015-06-24 F. Ricci , F. Massaro , M. Landoni , R. D'Abrusco , D. Milisavljevic , D. Stern , N. Masetti , A. Paggi , Howard A. Smith , G. Tosti

Searching for low energy counterparts of gamma-ray sources is one of the major challenges in modern gamma-ray astronomy. In the third Fermi source catalog about 30 % of detected sources are unidentified/unassociated Gamma-ray Sources…

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