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We present a temporal and spectral analysis of the gamma-ray flux from nine of the brightest flat spectrum radio quasars (FSRQs) detected with the Fermi Large Area Telescope (LAT) during its first eight years of operation, with the aim of…

High Energy Astrophysical Phenomena · Physics 2020-11-20 Atreya Acharyya , Paula M. Chadwick , Anthony M. Brown

Since its launch, the Fermi satellite has firmly identified 5 pulsar wind nebulae plus a large number of candidates, all powered by young and energetic pulsars. HESS J1857+026 is a spatially extended gamma-ray source detected by H.E.S.S.…

BL Lacertae is a blazar at the redshift of z = 0.069, eponym of the BL Lac blazar type. It is also a prototype of the low-frequency-peaked BL Lac (LBL) subclass. It was first detected in sub-TeV gamma-ray range by MAGIC in 2005. In 2015,…

The MAGIC collaboration reports the detection of the blazar S5 0716+714 z=0.31+-0.08 in very high energy gamma-rays. The observations were performed in November 2007 and in April 2008, and were triggered by the KVA telescope due to the high…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 H. Anderhub

The past 20 years have seen phenomenal progress in our understanding of BL Lac objects. They form part of the blazar class, which are radio-loud AGN whose relativistic jets are aligned along our line of sight. Several critical milestones…

Astrophysics · Physics 2007-05-23 C. Megan Urry

High-$z$ blazars (z $\geq 2.5$) are the most powerful class of persistent $\gamma$-ray sources in the Universe. These objects possess the highest jet powers and luminosities and have black hole masses often in excess of $10^9$ solar masses.…

High Energy Astrophysical Phenomena · Physics 2020-11-18 M. Kreter , A. Gokus , F. Krauß , M. Kadler , R. Ojha , S. Buson , J. Wilms , M. Böttcher

This paper presents the gamma-ray spectral and timing results from the long-term regular observations of Mrk 421 with the Large Area Telescope (LAT) onboard Fermi during 2008 August - 2023 August. We discerned six periods the relatively…

High Energy Astrophysical Phenomena · Physics 2025-03-05 B. Kapanadze , A. Gurchumelia , M. Aller

We present multiwavelength data for twelve blazars observed from 2008-2010 as part of an ongoing optical-infrared photometric monitoring project. Sources were selected to be bright, southern (dec < 20 deg) blazars observed by the Fermi…

High Energy Astrophysical Phenomena · Physics 2015-06-03 E. W. Bonning , C. M. Urry , C. Bailyn , M. Buxton , R. Chatterjee , P. Coppi , G. Fossati , J. Isler , L. Maraschi

As part of a program to identify the physical conditions in the jets of gamma-ray-flaring blazars detected by Fermi, including the role of shocks in the production of high-energy flaring, we obtained 4 years of 3-frequency, centimeter-band…

High Energy Astrophysical Phenomena · Physics 2015-02-09 M. F. Aller , P. A. Hughes , H. D. Aller , S. G. Jorstad , A. P. Marscher , V. Bala , T. Hovatta

The Fermi, Swift and INTEGRAL satellites, together with ground based (especially Cherenkov) telescopes made possible a great progress in our understanding of relativistic jets. We can now start to attack the difficult questions of jet…

High Energy Astrophysical Phenomena · Physics 2011-12-16 G. Ghisellini

Published EGRET spectra from blazars extend only to 10 GeV, yet EGRET has detected approximately 2000 gamma-rays above 10 GeV of which about half are at high Galactic latitude. We report a search of these high-energy gamma-rays for…

Astrophysics · Physics 2009-11-06 Brenda L. Dingus , David L. Bertsch

We present a study of the parsec-scale multi-frequency properties of the quasar S4 1030+61 during a prolonged radio and gamma-ray activity. Observations were performed within Fermi gamma-ray telescope, OVRO 40-m telescope and MOJAVE VLBA…

High Energy Astrophysical Phenomena · Physics 2016-09-14 E. V. Kravchenko , Y. Y. Kovalev , T. Hovatta , V. Ramakrishnan

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed as part of the VLBA Imaging and Polarimetry Survey (VIPS). This large, flux-limited sample of active…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 J. D. Linford , G. B. Taylor , R. Romani , S. E. Healey , J. F. Helmboldt , A. C. S. Readhead , R. Reeves , J. Richards , G. Cotter

In this presentation, we report the results of intraday variability in the optical (BVRI bands) and hard X-ray band (3-79 keV) in a number of blazars. In the optical microvariability studies of the blazars S5 0716+714 and BL Lac, we…

High Energy Astrophysical Phenomena · Physics 2022-10-18 Gopal Bhatta

The very-high-energy (VHE, $\gtrsim 100$ GeV) $\gamma$-ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z=0.368 or…

High Energy Astrophysical Phenomena · Physics 2019-08-15 MAGIC Collaboration , M. L. Ahnen , S. Ansoldi , L. A. Antonelli , C. Arcaro , D. Baack , A. Babić , B. Banerjee , P. Bangale , U. Barres de Almeida , J. A. Barrio , W. Bednarek , E. Bernardini , R. Ch. Berse , A. Berti , W. Bhattacharyya , A. Biland , O. Blanch , G. Bonnoli , R. Carosi , A. Carosi , G. Ceribella , A. Chatterjee , S. M. Colak , P. Colin , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , P. Cumani , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , M. Delfino , J. Delgado , F. Di Pierro , A. Domínguez , D. Dominis Prester , D. Dorner , M. Doro , S. Einecke , D. Elsaesser , V. Fallah Ramazani , A. Fernández-Barral , D. Fidalgo , M. V. Fonseca , L. Font , C. Fruck , D. Galindo , R. J. García López , M. Garczarczyk , M. Gaug , P. Giammaria , N. Godinović , D. Gora , D. Guberman , D. Hadasch , A. Hahn , T. Hassan , M. Hayashida , J. Herrera , J. Hose , D. Hrupec , K. Ishio , Y. Konno , H. Kubo , J. Kushida , D. Kuvež dić , D. Lelas , E. Lindfors , S. Lombardi , F. Longo , M. López , C. Maggio , P. Majumdar , M. Makariev , G. Maneva , M. Manganaro , K. Mannheim , L. Maraschi , M. Mariotti , M. Martínez , S. Masuda , D. Mazin , K. Mielke , M. Minev , J. M. Miranda , R. Mirzoyan , A. Moralejo , V. Moreno , E. Moretti , T. Nagayoshi , V. Neustroev , A. Niedzwiecki , M. Nievas Rosillo , C. Nigro , K. Nilsson , D. Ninci , K. Nishijima , K. Noda , L. Nogués , S. Paiano , J. Palacio , D. Paneque , R. Paoletti , J. M. Paredes , G. Pedaletti , M. Peresano , M. Persic , P. G. Prada Moroni , E. Prandini , I. Puljak , J. R. Garcia , I. Reichardt , W. Rhode , M. Ribó , J. Rico , C. Righi , A. Rugliancich , T. Saito , K. Satalecka , T. Schweizer , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Stamerra , M. Strzys , T. Surić , M. Takahashi , L. Takalo , F. Tavecchio , P. Temnikov , T. Terzić , M. Teshima , N. Torres-Albà , A. Treves , S. Tsujimoto , G. Vanzo , M. Vazquez Acosta , I. Vovk , J. E. Ward , M. Will , D. Zarić , J. Becerra González , Y. Tanaka , R. Ojha , J. Finke , A. Lähteenmäki , E. Järvelä , M. Tornikoski , V. Ramakrishnan , T. Hovatta , S. G. Jorstad , A. P. Marscher , V. M. Larionov , G. A. Borman , T. S. Grishina , E. N. Kopatskaya , L. V. Larionova , D. A. Morozova , S. S. Savchenko , Yu. V. Troitskaya , I. S. Troitsky , A. A. Vasilyev , I. Agudo , S. N. Molina , C. Casadio , M. Gurwell , M. I. Carnerero , C. Protasio , J. A Acosta Pulido

In 2008, the blazar Mrk421 entered in a very active phase and was one of the brightest sources in the sky at TeV energies, showing strong and frequent flaring. We searched for gamma-ray emission at energies E > 0.8 TeV during the whole 2008…

High Energy Astrophysical Phenomena · Physics 2009-07-16 G. Di Sciascio

Blazars radiate from relativistic jets launched by a supermassive black hole along our line of sight; the subclass of FSRQs exhibits broad emission lines, a telltale sign of a gas-rich environment and high accretion rate, contrary to the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Alessandro Paggi , Alfonso Cavaliere , Valerio Vittorini , Filippo D'Ammando , Marco Tavani

We study the quasi-simultaneous near-IR, optical, UV, and X-ray photometry of eleven gamma-ray selected blazars for which redshift estimates larger than 1.2 have been recently provided. Four of these objects turn out to be high-power…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 P. Padovani , P. Giommi , A. Rau