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We present an extensive X-ray spectral analysis of the cores of 19 FRII sources in the redshift range 0.5<z<1.0 which were selected to be matched in isotropic radio power. The sample consists of 10 radio galaxies and 9 quasars. We compare…

Astrophysics · Physics 2009-11-13 E. Belsole , D. M. Worrall , M. J. Hardcastle

We study the correlation between the gamma-ray flux F_g, averaged over the first 11 months of Fermi survey and integrated above 100 MeV, and the radio flux density (F_r at 20 GHz) of Fermi sources associated with a radio counterpart in the…

High Energy Astrophysical Phenomena · Physics 2015-05-19 G. Ghirlanda , G. Ghisellini , F. Tavecchio , L. Foschini , G. Bonnoli

Using the Urumqi 25m radio telescope, sources from the first three-month Fermi-LAT detected AGN catalog with declination >0 were observed in 2009 at 4.8 GHz. The radio flux density appears to correlate with the gamma-ray intensity.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Xiang Liu , Hua-Gang Song , Jun Liu , Zhen Ding , Nicola Marchili , Thomas P. Krichbaum , Lars Fuhrmann , Anton Zensus , Tao An

In this paper we study two newly discovered classes of radio sources: the highly energetic, short-lived events, known as Fast Radio Bursts (FRBs), and a new category of compact sources known as Fanaroff-Riley type 0 radio galaxies (FR0s).…

Astrophysics of Galaxies · Physics 2019-12-11 Sergio Best , José Bazo

Relativistic jets around supermassive black holes (SMBHs) are well-known powerful $\gamma$-ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in $\gamma$-ray bands is still unknown despite…

High Energy Astrophysical Phenomena · Physics 2025-06-25 Jun-Rong Liu , Jian-Min Wang , Fermi-LAT Collaboration

Non-blazar Active Galactic Nuclei (AGN) have emerged as a new gamma-ray emitting source class on the extragalactic sky and started to deepen our understanding of the physical processes and the nature of AGN in general. The detection of…

High Energy Astrophysical Phenomena · Physics 2017-07-10 Frank M. Rieger

Violent multi-wavelength variabilities are observed in gamma-ray-selected blazars. We present an analysis of long-term light curves for eight bright blazars to explore the co-variation pattern in the gamma-ray and radio bands. We extract…

High Energy Astrophysical Phenomena · Physics 2020-05-27 Hai-Ming Zhang , Zhen-Jie Wang , Jin Zhang , Ting-Feng Yi , Liang Chen , Rui-Jing Lu , En-Wei Liang

According to radiative models, radio galaxies and quasars are predicted to produce gamma rays from the earliest stages of their evolution. Exploring their high-energy emission is crucial for providing information on the most energetic…

We report the detection of a gamma-ray spectral line at approximately 1.5 GeV in three active galactic nuclei (AGN) using 17 years of Fermi-LAT observations. The sample includes both blazars (with relativistic jets directed toward Earth)…

High Energy Astrophysical Phenomena · Physics 2026-04-02 Shi-Ju Kang , Yue Yin , Yong-Gang Zheng , Qingwen Wu

Before the launch of the Fermi satellite only two classes of AGN were known to generate relativistic jets and thus emit up to the gamma-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first two…

High Energy Astrophysical Phenomena · Physics 2019-08-14 F. D'Ammando , G. Tosti , M. Orienti , J. Finke

We report on observations of TeV-selected AGN made during the first 5.5 months of observations with the Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope (Fermi). In total, 96 AGN were selected for study, each being…

High Energy Astrophysical Phenomena · Physics 2012-08-27 S. J. Fegan , D. Sanchez , Fermi LAT Collaboration , : , A. A. Abdo

Within the MOJAVE VLBA program (Monitoring of Jets in AGN with VLBA Experiments), we have accumulated observational data at 15 GHz for hundreds of jets in $\gamma$-ray bright active galactic nuclei since the beginning of the Fermi…

High Energy Astrophysical Phenomena · Physics 2021-12-23 I. G. Kramarenko , A. B. Pushkarev , Y. Y. Kovalev , M. L. Lister , T. Hovatta , T. Savolainen

In this study, we systematically studied the X-ray to GeV gamma-ray spectra of 61 {\it Fermi} Large Area Telescope (LAT) detected radio galaxies. We found an anticorrelation between peak frequency and peak luminosity in the high-energy…

High Energy Astrophysical Phenomena · Physics 2022-06-15 Yasushi Fukazawa , Hiroto Matake , Taishu Kayanoki , Yoshiyuki Inoue , Justin Finke

In an attempt to constrain and understand the emission mechanism of gamma rays, we perform a cross-correlation analysis of 15 blazars using light curves in millimetre, optical and gamma rays. We use discrete correlation function and…

High Energy Astrophysical Phenomena · Physics 2015-12-15 V. Ramakrishnan , T. Hovatta , M. Tornikoski , K. Nilsson , E. Lindfors , M. Baloković , A. Lähteenmäki , R. Reinthal , L. Takalo

In the framework of the TANAMI multi-wavelength and VLBI monitoring, we study the evolution of the parsec-scale radio emission in radio galaxies in the southern hemisphere and their relationship to the $\gamma$-ray properties. In this first…

As very high energy (~100 GeV) gamma rays travel over cosmological distances, their flux is attenuated through interactions with the extragalactic background light. Observations of distant gamma ray sources at energies between ~200 GeV and…

High Energy Astrophysical Phenomena · Physics 2011-03-31 Alexander V. Belikov , Lisa Goodenough , Dan Hooper

Fast radio bursts (FRBs) are a recently discovered class of GHz-band, ms-duration, Jy-level-flux astrophysical transients, which origin is still a mystery. Exploring their gamma-ray counterpart is crucial for constraining their origin and…

High Energy Astrophysical Phenomena · Physics 2023-07-05 G. Principe , L. Di Venere , M. Negro , N. Di Lalla , N. Omodei , R. Di Tria , M. N. Mazziotta , F. Longo

The {\it Fermi} satellite has detected $\sim$60 radio galaxies (RGs). In this study, we investigate the difference in the properties of X-ray spectra between GeV-loud RGs and GeV-quiet RGs. Our sample comprises 68 objects: 36 RGs detected…

High Energy Astrophysical Phenomena · Physics 2022-06-08 Taishu Kayanoki , Yasushi Fukazawa

We have used the VLBA at 5 GHz to observe all galaxies with nuclear radio flux densities above 3.5 mJy found in a VLA survey at 15 GHz of a sample of nearby LINER galaxies. All galaxies were detected revealing high brightness temperature…

Astrophysics · Physics 2009-10-31 Heino Falcke , Neil M. Nagar , Andrew S. Wilson , James S. Ulvestad

We present a catalog of gamma-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first 3 years of the Fermi Gamma-ray Space Telescope mission. This catalog complements the Second…

High Energy Astrophysical Phenomena · Physics 2013-04-16 David Paneque , Jean Ballet , Toby Burnett , Seth Digel , Pascal Fortin , Juergen Knoedlseder