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Active galactic nuclei (AGN) with jets seen at small viewing angles are the most luminous and abundant objects in the $\gamma$-ray sky. AGN with jets misaligned along the line-of-sight appear fainter in the sky, but are more numerous than…

High Energy Astrophysical Phenomena · Physics 2015-06-15 M. Di Mauro , F. Calore , F. Donato , M. Ajello , L. Latronico

We report on the discovery of one of the most extreme cases of high-frequency radio variability ever measured in active galactic nuclei (AGN), observed on timescales of days and exhibiting variability amplitudes of three to four orders of…

Variable emission is one of the defining characteristic of active galactic nuclei (AGN). While providing precious information on the nature and physics of the sources, variability is often challenging to observe with time- and…

Instrumentation and Methods for Astrophysics · Physics 2016-04-08 Matteo Giomi , Lucie Gerard , Gernot Maier

We perform a multi-band statistical analysis of core-dominated superluminal active galactic nuclei (AGN) detected with Fermi Large Area Telescope (LAT). The detection rate of $\gamma$-ray jets is found to be high for optically bright AGN.…

Cosmology and Nongalactic Astrophysics · Physics 2010-06-14 T. G. Arshakian , J. León-Tavares , J. Torrealba , V. H. Chavushyan

Active Galactic Nuclei (AGNs) are characterized by emission of radiation over more than 10 orders of magnitude in frequency. Therefore, the execution of extensive surveys of the sky, with different types of detectors, is providing the…

Interband lags in the optical continua of active galactic nuclei (AGN) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interband lags have been found in a few individual AGN…

Astrophysics of Galaxies · Physics 2025-07-08 Zhen-Bo Su , Zhen-Yi Cai , Hengxiao Guo , Mouyuan Sun , Jun-Xian Wang

We report our identification of three gigaelectronvolt $\gamma$-ray sources, 4FGL J0502.6+0036, 4FGL J1055.9+6507, and 4FGL J1708.2+5519, as Active Galactic Nuclei (AGNs). They are listed in the latest Fermi-LAT source catalog as…

High Energy Astrophysical Phenomena · Physics 2024-06-21 Shunhao Ji , Zhongxiang Wang , Qiangmeng Huang , Ruoheng Yang

This article focuses on certain variability and emission characteristics of Active Galactic Nuclei (AGN), especially their radio-loud subset consisting of quasars, BL Lacs and $\gamma$-ray detected narrow-line Seyfert 1 galaxies, all of…

Astrophysics of Galaxies · Physics 2019-06-28 Gopal-Krishna , Silke Britzen , Paul Wiita

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

Variability of active galactic nuclei (AGNs) has long been servicing as an essential avenue of exploring the accretion physics of black hole (BH). There are two commonly used methods for analyzing AGN variability. First, the AGN…

Astrophysics of Galaxies · Physics 2024-07-04 Zhen-Bo Su , Zhen-Yi Cai , Mouyuan Sun , Hengxiao Guo , Wei-Min Gu , Jun-Xian Wang

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 present results of recurrence analysis of 46 active galactic nuclei (AGN) using light curves from the 157-month catalog of the Swift Burst Alert Telescope (BAT) in the 14-150 keV band. We generate recurrence plots and compute recurrence…

High Energy Astrophysical Phenomena · Physics 2022-11-28 R. A. Phillipson , M. S. Vogeley , P. T. Boyd

Active galactic nuclei (AGNs) exhibit variability across the entire electromagnetic spectrum with distinct flaring episodes at different frequencies. The high sensitivity and nearly uniform sky coverage of the Large Area Telescope on board…

High Energy Astrophysical Phenomena · Physics 2022-03-02 Filippo D'Ammando

The detection of very-high-energy (VHE; $>$100 GeV) $\gamma$-ray radiation from misaligned jetted Active Galactic Nuclei (AGN) challenges the emission models that primarily explain VHE emissions from beamed AGN, i.e., blazars. Using over 16…

High Energy Astrophysical Phenomena · Physics 2025-08-25 Gunjan Tomar , Vaidehi S. Paliya , D. J. Saikia , C. S. Stalin

We present the multi-wavelength and environmental properties of 37 variability-selected active galactic nuclei (AGNs), including 30 low luminosity AGNs (LLAGNs), using a high cadence time-domain survey (ASAS-SN) from a spectroscopic sample…

Astrophysics of Galaxies · Physics 2025-01-30 Heechan Yuk , Xinyu Dai , Marko Mićić

The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic (TS) greater than 25,…

High Energy Astrophysical Phenomena · Physics 2015-09-16 M. Ackermann , M. Ajello , W. Atwood , L. Baldini , J. Ballet , G. Barbiellini , D. Bastieri , J. Gonzalez , R. Bellazzini , E. Bissaldi , R. Blandford , E. Bloom , R. Bonino , E. Bottacini , T. Brandt , J. Bregeon , R. Britto , P. Bruel , R. Buehler , S. Buson , G. Caliandro , R. Cameron , M. Caragiulo , P. Caraveo , J. Casandjian , E. Cavazzuti , C. Cecchi , E. Charles , A. Chekhtman , C. Cheung , J. Chiang , G. Chiaro , S. Ciprini , R. Claus , J. Cohen-Tanugi , L. Cominsky , J. Conrad , S. Cutini , R. D'Abrusco , F. D'Ammando , A. Angelis , R. Desiante , S. Digel , L. Venere , P. Drell , C. Favuzzi , S. Fegan , E. Ferrara , J. Finke , W. Focke , A. Franckowiak , L. Fuhrmann , A. Furniss , P. Fusco , F. Gargano , D. Gasparrini , N. Giglietto , P. Giommi , F. Giordano , M. Giroletti , T. Glanzman , G. Godfrey , I. Grenier , J. Grove , S. Guiriec , J. W. Hewitt , A. Hill , D. Horan , G. J'ohannesson , A. Johnson , W. Johnson , J. Kataoka , M. Kuss , G. Mura , S. Larsson , L. Latronico , C. Leto , J. Li , L. Li , F. Longo , F. Loparco , B. Lott , M. Lovellette , P. Lubrano , G. Madejski , M. Mayer , M. Mazziotta , J. McEnery , P. Michelson , T. Mizuno , A. Moiseev , M. Monzani , A. Morselli , I. Moskalenko , S. Murgia , E. Nuss , M. Ohno , T. Ohsugi , R. Ojha , N. Omodei , M. Orienti , E. Orlando , A. Paggi , D. Paneque , J. Perkins , M. Pesce-Rollins , F. Piron , G. Pivato , T. Porter , S. Rain`o , R. Rando , M. Razzano , S. Razzaque , A. Reimer , O. Reimer , R. Romani , D. Salvetti , M. Schaal , F. Schinzel , A. Schulz , C. Sgr`o , E. Siskind , K. Sokolovsky , F. Spada , G. Spandre , P. Spinelli , L. Stawarz , D. Suson , H. Takahashi , T. Takahashi , Y. Tanaka , J. Thayer , J. Thayer , L. Tibaldo , D. Torres , E. Torresi , G. Tosti , E. Troja , Y. Uchiyama , G. Vianello , B. Winer , K. Wood , S. Zimmer

The Fermi Gamma-ray Space Telescope is producing the most detailed inventory of the gamma-ray sky to date. Despite tremendous achievements approximately 25% of all Fermi extragalactic sources in the Second Fermi LAT Catalogue (2FGL) are…

High Energy Astrophysical Phenomena · Physics 2012-12-12 T. Hassan , N. Mirabal , J. L. Contreras , I. Oya

The long-term variability study over a range of black hole (BH) mass systems from the microquasars of stellar-mass black holes to the Active Galactic Nuclei (AGNs) of supermassive black holes, in $\gamma$-rays offers new insights into the…

High Energy Astrophysical Phenomena · Physics 2024-10-10 Ajay Sharma , Raj Prince , Debanjan Bose

Active Galactic Nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty…

During its first four years of scientific observations, the Fermi Large Area Telescope (Fermi-LAT) detected 3033 $\gamma$-ray sources above a 4$\sigma$ significance level. Although most of the extra-Galactic sources are active galactic…

High Energy Astrophysical Phenomena · Physics 2019-08-15 G. La Mura , G. Chiaro , S. Ciroi , P. Rafanelli , D. Salvetti , M. Berton , V. Cracco