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Blazars can be detected from very large distances due to their high luminosity. However, the detection of $\gamma$-ray emission of blazars beyond $z=3$ has only been confirmed for a small number of sources. Such observations probe the…

Relativistic amplification boosts the contribution of the jet base to the total emission in blazars, thus making single dish observations useful and practical to characterise their physical state, particularly during episodes of enhanced…

Instrumentation and Methods for Astrophysics · Physics 2020-01-15 Marcello Giroletti , Simona Righini

B2013+370 and B2023+336 are two blazars at low-galactic latitude that were previously proposed to be the counterparts for the EGRET unidentified sources, 3EG J2016+3657 and 3EG J2027+3429. Gamma-ray emission associated with the EGRET…

High Energy Astrophysical Phenomena · Physics 2015-06-03 E. Kara , M. Errando , W. Max-Moerbeck , E. Aliu , M. Bottcher , P. Fortin , J. P. Halpern , R. Mukherjee , A. C. S. Readhead , J. L. Richards

In this work, starting from 21 months of data from the Fermi-Large Area Telescope, we derive maps of the residual isotropic gamma-ray emission, a relevant fraction of which is expected to be contributed by the extragalactic diffuse…

Cosmology and Nongalactic Astrophysics · Physics 2011-10-04 Jun-Qing Xia , Alessandro Cuoco , Enzo Branchini , Mattia Fornasa , Matteo Viel

We present deep optical and X-ray follow-up observations of the bright unassociated Fermi-LAT gammaray source 1FGL J1311.7-3429. The source was already known as an unidentified EGRET source (3EG J1314-3431, EGR J1314-3417), hence its nature…

High Energy Astrophysical Phenomena · Physics 2015-06-11 J. Kataoka , Y. Yatsu , N. Kawai , Y. Urata , C. C. Cheung , Y. Takahashi , K. Maeda , T. Totani , R. Makiya , H. Hanayama , T. Miyaji , A. Tsai

We report evidence for extended gamma-ray emission from the Virgo, Fornax and Coma clusters based on a maximum-likelihood analysis of the 3-year Fermi-LAT data. For all three clusters, excess emission is observed within three degrees of the…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Jiaxin Han , Carlos S. Frenk , Vincent R. Eke , Liang Gao , Simon D. M. White

Radio galaxies are uncommon $\gamma$-ray emitters, and only low redshift radio galaxies are detected with Fermi-LAT. However, they offer potential insights into the emission mechanisms of active galaxies, particularly as the alignment of…

High Energy Astrophysical Phenomena · Physics 2020-06-17 Max Harvey , Cameron B. Rulten , Paula M. Chadwick

We present an analysis of high energy (HE; 0.1-300 GeV) gamma-ray observations of 1FGL J1227.9-4852 with the Fermi Gamma-ray Space Telescope, follow-up radio observations with the Australia Telescope Compact Array, Giant Metrewave Radio…

High Energy Astrophysical Phenomena · Physics 2012-11-27 A. B. Hill , A. Szostek , S. Corbel , F. Camilo , R. H. D. Corbet , R. Dubois , G. Dubus , P. G. Edwards , E. C. Ferrara , M. Kerr , E. Koerding , D. Kozieł , Ł. Stawarz

We study the $\rm{\gamma}$-ray luminosity and beaming effect for Fermi blazars. Our results are as follows. (i) There are significant correlations between $\rm{\gamma}$-ray luminosity and radio core luminosity, and between $\rm{\gamma}$-ray…

High Energy Astrophysical Phenomena · Physics 2016-01-20 Yong-Yun Chen , Xiong Zhang , Dingrong Xiong , Si-Ju Wang , Xiaoling Yu

Although the Fermi mission has increased our knowledge of gamma-ray AGN, many questions remain, such as the site of gamma-ray production, the emission mechanism, and the factors that govern the strength of the emission. Using data from a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 E. Nieppola , M. Tornikoski , E. Valtaoja , J. León-Tavares , T. Hovatta , A. Lähteenmäki , J. Tammi

The Fermi LAT has detected numerous transient gamma-ray sources near the Galactic plane, several of which have been shown to be located within our Galaxy. We present an analysis of LAT Pass 8 data of seven previously reported, but still…

High Energy Astrophysical Phenomena · Physics 2018-01-18 Dirk Pandel

Since the launch of the Fermi gamma - ray Space Telescope on June 11, 2008, the LAT instrument has solidly detected more than 20 GRBs with high energy photon emission above 100 MeV. Using the matched filter technique, 3 more GRBs have also…

High Energy Astrophysical Phenomena · Physics 2012-01-19 WeiKang Zheng , Carl W. Akerlof , Shashi B. Pandey , Timothy A. McKay , BinBin Zhang , Bing Zhang

The Gamma-ray detection from an astrophysical object indicates the presence of an extreme environment where high-energy radiation is produced. With the continuous monitoring of the Gamma-ray sky by the Fermi Large Area Telescope (LAT),…

High Energy Astrophysical Phenomena · Physics 2024-12-18 Subhashree Swain , Vaidehi S. Paliya , D. J. Saikia , C. S. Stalin

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

Using high-resolution radio imaging with VLBI techniques, the TANAMI program has been observing the parsec-scale radio jets of southern (declination south of -30{\deg}) gamma-ray bright AGN simultaneously with Fermi/LAT monitoring of their…

During a search for gamma-ray emission from NGC 3628 (Arp 317), two new unidentified gamma-ray sources, Fermi J1049.7+0435 and J1103.2+1145 have been discovered \cite{ATel}. The detections are made in data from the Large Area Telescope…

High Energy Astrophysical Phenomena · Physics 2015-02-10 Masaki Nishimichi , Takeshi Okuda , Masaki Mori , Philip G. Edwards , Jamie Stevens

We compute the contribution of blazars (Flat Spectrum Radio Quasars and BL-Lacs) to the Fermi-LAT Extragalactic gamma-ray Background, assuming a gamma-ray luminosity function proportional to the luminosity function of radio galaxies and the…

High Energy Astrophysical Phenomena · Physics 2011-11-01 Massimo Cavadini , Ruben Salvaterra , Francesco Haardt

Based on the experience gained during the four and a half years of the mission, the Fermi -LAT collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet…

Supernovae (SNe) exploding in a dense circumstellar medium (CSM) are predicted to accelerate cosmic rays in collisionless shocks and emit GeV gamma rays and TeV neutrinos on a time scale of several months. Here we summarize the results of…

High Energy Astrophysical Phenomena · Physics 2015-07-15 A. Franckowiak , K. Murase , E. O. Ofek

Recently, a spatially extended excess of gamma rays collected by the Fermi-LAT from the inner region of the Milky Way has been detected by different groups and with increasingly sophisticated techniques. Yet, any final conclusion about the…

High Energy Astrophysical Phenomena · Physics 2015-02-11 Francesca Calore , Ilias Cholis , Christoph Weniger