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We present $\gamma$-ray, X-ray, ultraviolet, optical, and near-infrared light curves of 33 $\gamma$-ray bright blazars over four years that we have been monitoring since 2008 August with multiple optical, ground-based telescopes and the…

Characteristic variability timescales in blazar gamma-ray light curves can provide insight into the physical processes responsible for the gamma-ray variability. The power spectral density (PSD) is capable of revealing such timescales,…

High Energy Astrophysical Phenomena · Physics 2019-11-06 James L. Ryan , Aneta Siemiginowska , Malgosia Sobolewska , Jonathan Grindlay

The Fermi Large Area Telescope (LAT) has detected more than 5000 gamma-ray sources in its first 8 years of operation. More than 3000 of them are blazars. About 60 per cent of the Fermi-LAT blazars are classified as BL Lacertae objects (BL…

High Energy Astrophysical Phenomena · Physics 2020-06-22 Miloš Kovačević , Graziano Chiaro , Sara Cutini , Gino Tosti

In this catalog we present the updated set of spectral analyses of GRBs detected by the Fermi Gamma-Ray Burst Monitor (GBM) during its first four years of operation. It contains two types of spectra, time-integrated spectral fits and…

Here we present the first optical photometric monitoring results of a sample of twelve newly discovered blazars from the ICRF - Gaia CRF astrometric link. The observations were performed from April 2013 until August 2019 using eight…

High Energy Astrophysical Phenomena · Physics 2023-04-26 Miljana D. Jovanovic , Goran Damljanovic , Francois Taris , Alok C. Gupta , Gopal Bhatta

A wide-frequency radio study of Active Galactic Nuclei (AGN) is crucial to evaluate the intervening radiative mechanisms responsible for the observed emission and relate them with the underlying accretion physics. We present wide frequency…

We present the second catalog of flaring gamma-ray sources (2FAV) detected with the Fermi All-sky Variability Analysis (FAVA), a tool that blindly searches for transients over the entire sky observed by the Large Area Telescope (LAT) on…

High Energy Astrophysical Phenomena · Physics 2017-09-13 S. Abdollahi , M. Ackermann , M. Ajello , A. Albert , L. Baldini , J. Ballet , G. Barbiellini , D. Bastieri , J. Becerra Gonzalez , R. Bellazzini , E. Bissaldi , R. D. Blandford , E. D. Bloom , R. Bonino , E. Bottacini , J. Bregeon , P. Bruel , R. Buehler , S. Buson , R. A. Cameron , M. Caragiulo , P. A. Caraveo , E. Cavazzuti , C. Cecchi , A. Chekhtman , C. C. Cheung , G. Chiaro , S. Ciprini , J. Conrad , D. Costantin , F. Costanza , S. Cutini , F. D'Ammando , F. de Palma , A. Desai , R. Desiante , S. W. Digel , N. Di Lalla , M. Di Mauro , L. Di Venere , B. Donaggio , P. S. Drell , C. Favuzzi , S. J. Fegan , E. C. Ferrara , W. B. Focke , A. Franckowiak , Y. Fukazawa , S. Funk , P. Fusco , F. Gargano , D. Gasparrini , N. Giglietto , M. Giomi , F. Giordano , M. Giroletti , T. Glanzman , D. Green , I. A. Grenier , J. E. Grove , L. Guillemot , S. Guiriec , E. Hays , D. Horan , T. Jogler , G. Jóhannesson , A. S. Johnson , D. Kocevski , M. Kuss , G. La Mura , S. Larsson , L. Latronico , J. Li , F. Longo , F. Loparco , M. N. Lovellette , P. Lubrano , J. D. Magill , S. Maldera , A. Manfreda , M. Mayer , M. N. Mazziotta , P. F. Michelson , W. Mitthumsiri , T. Mizuno , M. E. Monzani , A. Morselli , I. V. Moskalenko , M. Negro , E. Nuss , T. Ohsugi , N. Omodei , M. Orienti , E. Orlando , V. S. Paliya , D. Paneque , J. S. Perkins , M. Persic , M. Pesce-Rollins , V. Petrosian , F. Piron , T. A. Porter , G. Principe , S. Rainò , R. Rando , M. Razzano , S. Razzaque , A. Reimer , O. Reimer , C. Sgrò , D. Simone , E. J. Siskind , F. Spada , G. Spandre , P. Spinelli , L. Stawarz , D. J. Suson , M. Takahashi , K. Tanaka , J. B. Thayer , D. J. Thompson , D. F. Torres , E. Torresi , G. Tosti , E. Troja , G. Vianello , K. S. Wood

Blazars are a class of active galactic nuclei (AGNs) known for their very rapid variabilty in the high energy regions of the electromagnetic spectrum. Despite this known fast variability, X-ray observations have generally not revealed…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Matthew Pryal , Abe Falcone , Michael Stroh

We study the variability properties at radio frequencies of the jets thought to be typical of Active Galactic Nuclei, i.e. bulk Lorentz factor \Gamma ~ 10, and incoherent synchrotron emission. We assume that the radiating electrons are…

Astrophysics · Physics 2009-10-30 M. Spada , M. Salvati , F. Pacini

The exact location of the gamma-ray emitting region in blazars is still controversial. In order to attack this problem we present first results of a cross-correlation analysis between radio (11 cm to 0.8 mm wavelength, F-GAMMA program) and…

Context. The advent of Fermi is changing our understanding on the radio and gamma-ray emission in Active Galactic Nuclei. Contrary to pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the gamma-ray band. However,…

High Energy Astrophysical Phenomena · Physics 2015-06-17 E. Liuzzo , M. Giroletti , G. Giovannini , B. Boccardi , S. Tamburri , G. B. Taylor , C. Casadio , M. Kadler , G. Tosti , A. Mignano

High redshift blazars are among the most powerful non-explosive sources in the Universe and play a crucial role in understanding the evolution of relativistic jets. To understand these bright objects, we performed a detailed investigation…

High Energy Astrophysical Phenomena · Physics 2024-01-29 N. Sahakyan , G. Harutyunyan , S. Gasparyan , D. Israyelyan

S5 0716+714 is a typical BL Lacertae object. In this paper we present the analysis and results of long term simultaneous observations in the radio, near-infrared, optical, X-ray and $\gamma$-ray bands, together with our own photometric…

High Energy Astrophysical Phenomena · Physics 2015-06-18 N. H. Liao , J. M. Bai , H. T. Liu , S. S. Weng , Liang Chen , F. Li

The first three months of sky-survey operation with the Fermi Gamma Ray Space Telescope (Fermi) Large Area Telescope (LAT) reveals 132 bright sources at |b|>10 deg with test statistic greater than 100 (corresponding to about 10 sigma). Two…

High Energy Astrophysical Phenomena · Physics 2009-09-30 A. A. Abdo

Motivated by the detection of a hardening in the gamma-ray spectrum of the radio galaxy Centaurus A, we have analysed ~10 years of Fermi-LAT observations of 26 radio galaxies to search for similar spectral features. We find that the…

High Energy Astrophysical Phenomena · Physics 2020-01-14 Cameron B. Rulten , Anthony M. Brown , Paula M. Chadwick

Most extragalactic jets in radio-loud Active Galactic Nuclei are bright and variable gamma-ray sources, which are continuously monitored with Fermi/LAT. We present the gamma-ray properties of the MOJAVE and TANAMI AGN samples of radio-loud…

Cosmology and Nongalactic Astrophysics · Physics 2010-06-15 M. Boeck , M. Kadler , G. Tosti , T. H. Burnett , C. Mueller , R. Ojha , J. Wilms

We investigate the spectral properties of the brightest gamma-ray flares of blazars detected by the Fermi Large Area Telescope. We search for the presence of spectral breaks and measure the spectral curvature on typical time scales of a few…

High Energy Astrophysical Phenomena · Physics 2015-06-24 Susanna Kohler , Krzysztof Nalewajko

Jetted Active Galactic Nuclei (AGN) exhibit variability across a wide range of time scales. Traditionally, this variability can often be modeled well as a stochastic process. However, in certain cases, jetted AGN variability displays…

High Energy Astrophysical Phenomena · Physics 2025-01-03 P. Penil , A. Domínguez , S. Buson , M. Ajello , S. Adhikari , A. Rico

We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the Active Galactic Nuclei (AGN) detected by Fermi during its first year of operation, with the largest datasets ever used for this…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 M. Ackermann , M. Ajello , A. Allafort , E. Angelakis , M. Axelsson , L. Baldini , J. Ballet , G. Barbiellini , D. Bastieri , R. Bellazzini , B. Berenji , R. D. Blandford , E. D. Bloom , E. Bonamente , A. W. Borgland , A. Bouvier , J. Bregeon , A. Brez , M. Brigida , P. Bruel , R. Buehler , S. Buson , G. A. Caliandro , R. A. Cameron , A. Cannon , P. A. Caraveo , J. M. Casandjian , E. Cavazzuti , C. Cecchi , E. Charles , A. Chekhtman , C. C. Cheung , S. Ciprini , R. Claus , J. Cohen-Tanugi , S. Cutini , F. de Palma , C. D. Dermer , E. do Couto e Silva , P. S. Drell , R. Dubois , D. Dumora , L. Escande , C. Favuzzi , S. J. Fegan , W. B. Focke , P. Fortin , M. Frailis , L. Fuhrmann , Y. Fukazawa , P. Fusco , F. Gargano , D. Gasparrini , N. Gehrels , N. Giglietto , P. Giommi , F. Giordano , M. Giroletti , T. Glanzman , G. Godfrey , P. Grandi , I. A. Grenier , S. Guiriec , D. Hadasch , M. Hayashida , E. Hays , S. E. Healey , G. J , A. S. Johnson , T. Kamae , H. Katagiri , J. Kataoka , J. Kn , M. Kuss , J. Lande , S. -H. Lee , F. Longo , F. Loparco , B. Lott , M. N. Lovellette , P. Lubrano , A. Makeev , W. Max-Moerbeck , M. N. Mazziotta , J. E. McEnery , J. Mehault , P. F. Michelson , T. Mizuno , C. Monte , M. E. Monzani , A. Morselli , I. V. Moskalenko , S. Murgia , M. Naumann-Godo , S. Nishino , P. L. Nolan , J. P. Norris , E. Nuss , T. Ohsugi , A. Okumura , N. Omodei , E. Orlando , J. F. Ormes , M. Ozaki , D. Paneque , V. Pavlidou , V. Pelassa , M. Pepe , M. Pesce-Rollins , M. Pierbattista , F. Piron , T. A. Porter , S. Rain , M. Razzano , A. Readhead , A. Reimer , O. Reimer , J. L. Richards , R. W. Romani , H. F. -W. Sadrozinski , J. D. Scargle , C. Sgr , E. J. Siskind , P. D. Smith , G. Spandre , P. Spinelli , M. S. Strickman , D. J. Suson , H. Takahashi , T. Tanaka , G. B. Taylor , J. G. Thayer , J. B. Thayer , D. J. Thompson , D. F. Torres , G. Tosti , A. Tramacere , E. Troja , J. Vandenbroucke , G. Vianello , V. Vitale , A. P. Waite , P. Wang , B. L. Winer , K. S. Wood , Z. Yang , M. Ziegler

Context. X-ray spectral variability analyses of active galactic nuclei (AGN) with moderate luminosities and redshifts typically show a softer when brighter behaviour. Such a trend has rarely been investigated for high-luminosity AGNs ($…

Astrophysics of Galaxies · Physics 2017-04-12 R. Serafinelli , F. Vagnetti , R. Middei