Related papers: Is PKS 0625-354 another variable TeV active galact…

Recent H.E.S.S. results on extra-galactic sources

Since the beginning of scientific operations in 2003, more than 20 extra-galactic sources have been detected with H.E.S.S. (High Energy Stereoscopic System) at very high energies (VHE): apart from the starburst galaxy NGC 253, all of them…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-14 Matteo Cerruti

VHE gamma-ray emission of PKS 2155-304: spectral and temporal variability

Observations of very high energy gamma-rays from blazars provide information about acceleration mechanisms occurring in their innermost regions. Studies of variability in these objects allow a better understanding of the mechanisms at play.…

High Energy Astrophysical Phenomena · Physics 2015-05-19 HESS Collaboration , A. Abramowski , F. Acero , F. Aharonian , A. G. Akhperjanian , G. Anton , U. Barres de Almeida , A. R. Bazer-Bachi , Y. Becherini , B. Behera , W. Benbow , K. Bernlohr , A. Bochow , C. Boisson , J. Bolmont , V. Borrel , J. Brucker , F. Brun , P. Brun , R. Buhler , T. Bulik , I. Busching , T. Boutelier , P. M. Chadwick , A. Charbonnier , R. C. G. Chaves , A. Cheesebrough , J. Conrad , L. -M. Chounet , A. C. Clapson , G. Coignet , L. Costamante , M. Dalton , M. K. Daniel , I. D. Davids , B. Degrange , C. Deil , H. J. Dickinson , A. Djannati-Atai , W. Domainko , L. O'C. Drury , F. Dubois , G. Dubus , J. Dyks , M. Dyrda , K. Egberts , P. Eger , P. Espigat , L. Fallon , C. Farnier , S. Fegan , F. Feinstein , M. V. Fernandes , A. Fiasson , A. Foerster , G. Fontaine , M. Fussling , S. Gabici , Y. A. Gallant , L. Gerard , D. Gerbig , B. Giebels , J. F. Glicenstein , B. Glueck , P. Goret , D. Goering , D. Hampf , M. Hauser , S. Heinz , G. Heinzelmann , G. Henri , G. Hermann , J. A. Hinton , A. Hoffmann , W. Hofmann , P. Hofverberg , M. Holleran , S. Hoppe , D. Horns , A. Jacholkowska , O. C. de Jager , C. Jahn , I. Jung , K. Katarzynski , U. Katz , S. Kaufmann , M. Kerschhaggl , D. Khangulyan , B. Khelifi , D. Keogh , D. Klochkov , W. Kluzniak , T. Kneiske , Nu. Komin , K. Kosack , R. Kossakowski , G. Lamanna , J. -P. Lenain , T. Lohse , C. -C. Lu , V. Marandon , A. Marcowith , J. Masbou , D. Maurin , T. J. L. McComb , M. C. Medina , J. Mehault , R. Moderski , E. Moulin , M. Naumann-Godo , M. de Naurois , D. Nedbal , D. Nekrassov , N. Nguyen , B. Nicholas , J. Niemiec , S. J. Nolan , S. Ohm , J-F. Olive , E. de Ona Wilhelmi , B. Opitz , K. J. Orford , M. Ostrowski , M. Panter , M. Paz Arribas , G. Pedaletti , G. Pelletier , P. -O. Petrucci , S. Pita , G. Puehlhofer , M. Punch , A. Quirrenbach , B. C. Raubenheimer , M. Raue , S. M. Rayner , O. Reimer , M. Renaud , R. de los Reyes , F. Rieger , J. Ripken , L. Rob , S. Rosier-Lees , G. Rowell , B. Rudak , C. B. Rulten , J. Ruppel , F. Ryde , V. Sahakian , A. Santangelo , R. Schlickeiser , F. M. Schoeck , A. Schoenwald , U. Schwanke , S. Schwarzburg , S. Schwemmer , A. Shalchi , I. Sushch , M. Sikora , J. L. Skilton , H. Sol , L. Stawarz , R. Steenkamp , C. Stegmann , F. Stinzing , G. Superina , A. Szostek , P. H. Tam , J. -P. Tavernet , R. Terrier , O. Tibolla , M. Tluczykont , K. Valerius , C. van Eldik , G. Vasileiadis , C. Venter , L. Venter , J. P. Vialle , A. Viana , P. Vincent , M. Vivier , H. J. Voelk , F. Volpe , S. Vorobiov , S. J. Wagner , M. Ward , A. A. Zdziarski , A. Zech , H. -S. Zechlin

A New Sample of Gamma-Ray Emitting Jetted Active Galactic Nuclei -- Preliminary Results

We are compiling a new list of gamma-ray jetted active galactic nuclei (AGN), starting from the fourth catalog of point sources of the Fermi Large Area Telescope (LAT). Our aim is to prepare a list of jetted AGN with known redshifts and…

High Energy Astrophysical Phenomena · Physics 2021-10-06 L. Foschini , M. L. Lister , S. Antón , M. Berton , S. Ciroi , M. J. M. Marchã , M. Tornikoski , E. Järvelä , P. Romano , S. Vercellone , E. Dalla Bontà

A Connection Between Apparent VLBA Jet Speeds and Initial Active Galactic Nucleus Detections Made by the Fermi Gamma-ray Observatory

In its first three months of operations, the Fermi Gamma-Ray Observatory has detected approximately one quarter of the radio-flux-limited MOJAVE sample of bright flat-spectrum active galactic nuclei (AGNs) at energies above 100 MeV. We have…

Astrophysics of Galaxies · Physics 2011-02-11 M. L. Lister , D. C. Homan , M. Kadler , K. I. Kellermann , Y. Y. Kovalev , E. Ros , T. Savolainen , J. A. Zensus

New Insight from the James Webb Space Telescope on Variable Active Galactic Nuclei

Variability detected in galaxies is usually attributed to their active galactic nuclei (AGNs). While all AGNs are intrinsically variable, the AGN unification model predicts that type~2 AGNs rarely vary because their engines are blocked by…

Astrophysics of Galaxies · Physics 2026-02-17 Bangzheng Sun , Haojing Yan , Wei Leong Tee , Feige Wang

Gamma rays from the quasar PKS 1441+25: story of an escape

Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the Universe. The detection of significant emission above 100 GeV from a distant…

High Energy Astrophysical Phenomena · Physics 2015-12-23 A. U. Abeysekara , S. Archambault , A. Archer , T. Aune , A. Barnacka , W. Benbow , R. Bird , J. Biteau , J. H. Buckley , V. Bugaev , J. V Cardenzana , M. Cerruti , X. Chen , J. L. Christiansen , L. Ciupik , M. P. Connolly , P. Coppi , W. Cui , H. J. Dickinson , J. Dumm , J. D. Eisch , M. Errando , A. Falcone , Q. Feng , J. P. Finley , H. Fleischhack , A. Flinders , P. Fortin , L. Fortson , A. Furniss , G. H. Gillanders , S. Griffin , J. Grube , G. Gyuk , M. Hütten , N. Håkansson , D. Hanna , J. Holder , T. B. Humensky , C. A. Johnson , P. Kaaret , P. Kar , N. Kelley-Hoskins , Y. Khassen , D. Kieda , M. Krause , F. Krennrich , S. Kumar , M. J. Lang , G. Maier , S. McArthur , A. McCann , K. Meagher , P. Moriarty , R. Mukherjee , D. Nieto , A. O'Faoláin de Bhróithe , R. A. Ong , A. N. Otte , N. Park , J. S. Perkins , A. Petrashyk , M. Pohl , A. Popkow , E. Pueschel , J. Quinn , K. Ragan , G. Ratliff , P. T. Reynolds , G. T. Richards , E. Roache , J. Rousselle , M. Santander , G. H. Sembroski , K. Shahinyan , A. W. Smith , D. Staszak , I. Telezhinsky , N. W. Todd , J. V. Tucci , J. Tyler , V. V. Vassiliev , S. Vincent , S. P. Wakely , O. M. Weiner , A. Weinstein , A. Wilhelm , D. A. Williams , B. Zitzer , P. S. Smith , T. W. -S. Holoien , J. L. Prieto , C. S. Kochanek , K. Z. Stanek , B. Shappee , T. Hovatta , W. Max-Moerbeck , T. J. Pearson , R. A. Reeves , J. L. Richards , A. C. S. Readhead , G. M. Madejski , S. G. Djorgovski , A. J. Drake , M. J. Graham , A. Mahabal

Observations of Selected AGN with H.E.S.S

A sample of selected active galactic nuclei (AGN) was observed in 2003 and 2004 with the High Energy Stereoscopic System (H.E.S.S.), an array of imaging atmospheric-Cherenkov telescopes in Namibia. The redshifts of these candidate…

Astrophysics · Physics 2007-05-23 F. Aharonian et al.

High-resolution radio imaging of the gamma-ray blazar candidate J1331+2932

Active galactic nuclei are the most luminous persistent (non-transient, even if often variable) objects in the Universe. They are bright in the entire electromagnetic spectrum. Blazars are a special class where the jets point nearly to our…

Astrophysics of Galaxies · Physics 2019-02-21 A. Gemes , K. É. Gabányi , S. Frey , T. An , Z. Paragi , A. Moór

TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry. III. First-epoch S band images

With the emergence of very high energy astronomy (VHE; E>100 GeV), new open questions were presented to astronomers studying the multi-wavelength emission from blazars. Answers to these open questions, such as the Doppler crisis, and…

High Energy Astrophysical Phenomena · Physics 2024-01-17 Petra Benke , Florian Rösch , Eduardo Ros , Matthias Kadler , Roopesh Ojha , Philip G. Edwards , Shinji Horiuchi , Lucas J. Hyland , Chris Phillips , Jonathan F. H. Quick , Jamie Stevens , Anastasios K. Tzioumis , Stuart Weston

VHE gamma-ray emission from the FSRQs observed by the MAGIC telescopes

Among more than fifty blazars detected in very high energy (VHE, E>100GeV) gamma-rays, only three belong to the subclass of Flat Spectrum Radio Quasars (FSRQs): PKS 1510-089, PKS 1222+216 and 3C 279. The detection of FSRQs in the VHE range…

High Energy Astrophysical Phenomena · Physics 2019-08-15 E. Lindfors , K. Nilsson , U. Barres de Almeida , D. Mazin , D. Paneque , K. Saito , J. Becerra Gonzalez , K. Berger , G. De Caneva , C. Schultz , J. Sitarek , A. Stamerra , F. Tavecchio , S. Buson , F. D'Ammando , M. Hayashida , A. Lähteenmäki , M. Tornikoski , T. Hovatta

The Gamma-Ray Detected Narrow-Line Seyfert 1 Galaxy 1H 0323+342: Swift Monitoring and Suzaku Spectroscopy

As a radio-loud narrow-line Seyfert 1 galaxy (NLS1) detected by Fermi/LAT in GeV $\gamma$-rays, 1H 0323+342 is a remarkable Active Galactic Nucleus (AGN) showing properties characteristic of both NLS1s and blazars. Here we present results…

High Energy Astrophysical Phenomena · Physics 2015-05-07 Su Yao , Weimin Yuan , S. Komossa , Dirk Grupe , L. Fuhrmann , Bifang Liu

Search for Magnetically Broadened Cascade Emission From Blazars with VERITAS

We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGN), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma rays from AGN interact with…

High Energy Astrophysical Phenomena · Physics 2017-02-07 VERITAS Collaboration , S. Archambault , A. Archer , W. Benbow , M. Buchovecky , V. Bugaev , M. Cerruti , M. P. Connolly , W. Cui , A. Falcone , M. Fernández Alonso , J. P. Finley , H. Fleischhack , L. Fortson , A. Furniss , S. Griffin , M. Hütten , O. Hervet , J. Holder , T. B. Humensky , C. A. Johnson , P. Kaaret , P. Kar , D. Kieda , M. Krause , F. Krennrich , M. J. Lang , T. T. Y. Lin , G. Maier , S. McArthur , P. Moriarty , D. Nieto , S. O'Brien , R. A. Ong , A. N. Otte , M. Pohl , A. Popkow , E. Pueschel , J. Quinn , K. Ragan , P. T. Reynolds , G. T. Richards , E. Roache , A. C. Rovero , I. Sadeh , K. Shahinyan , D. Staszak , I. Telezhinsky , J. Tyler , S. P. Wakely , A. Weinstein , T. Weisgarber , P. Wilcox , A. Wilhelm , D. A. Williams , B. Zitzer

New active galactic nuclei detected in ROSAT All Sky Survey galaxies; Part I: Verification of selection strategy

We present the first results of a program to identify so far unknown active nuclei (AGN) in galaxies. Candidate galactic nuclei have been selected for optical spectroscopy from a cross-correlation of the ROSAT All Sky Survey (RASS) bright…

Astrophysics · Physics 2007-05-23 W. Pietsch , Th. Boller , S. Doebereiner , H. -U. Zimmermann , K. Bischoff , W. Kollatschny

Variability in active galactic nuclei: confrontation of models with observations

The variability of active galactic nuclei (AGN) has long held the promise of shedding light on their detailed structure, and possibly other astrophysical phenonema. Different emission mechanisms lead to different patterns of variability in…

Astrophysics · Physics 2009-11-07 M. R. S. Hawkins

The growing family of gamma-ray narrow-line Seyfert 1 galaxies

The revision of the fourth Fermi Large Area Telescope (LAT) catalog of gamma-ray point sources (rev4FGL) revealed that the gamma-ray sky is populated by emerging populations of jetted active galactic nuclei (AGN) other than blazars and…

High Energy Astrophysical Phenomena · Physics 2026-01-27 Luigi Foschini

The Subaru/XMM-Newton Deep Survey (SXDS) - VI. Properties of Active Galactic Nuclei Selected by Optical Variability

We present the properties of active galactic nuclei (AGN) selected by optical variability in the Subaru/XMM-Newton Deep Field (SXDF). Based on the locations of variable components and light curves, 211 optically variable AGN were reliably…

Astrophysics · Physics 2009-11-13 Tomoki Morokuma , Mamoru Doi , Naoki Yasuda , Masayuki Akiyama , Kazuhiro Sekiguchi , Hisanori Furusawa , Yoshihiro Ueda , Tomonori Totani , Takeshi Oda , Tohru Nagao , Nobunari Kashikawa , Takashi Murayama , Masami Ouchi , Mike G. Watson

AGILE detection of extreme gamma-ray activity from the blazar PKS 1510-089 during March 2009. Multifrequency analysis

We report on the extreme gamma-ray activity from the FSRQ PKS 1510-089 observed by AGILE in March 2009. In the same period a radio-to-optical monitoring of the source was provided by the GASP-WEBT and REM. Moreover, several Swift ToO…

High Energy Astrophysical Phenomena · Physics 2011-06-16 F. D'Ammando , C. M. Raiteri , M. Villata , P. Romano , G. Pucella , H. A. Krimm , S. Covino , M. Orienti , G. Giovannini , S. Vercellone , E. Pian , I. Donnarumma , V. Vittorini , M. Tavani , A. Argan , G. Barbiellini , F. Boffelli , A. Bulgarelli , P. Caraveo , P. W. Cattaneo , A. W. Chen , V. Cocco , E. Costa , E. Del Monte , G. De Paris , G. Di Cocco , Y. Evangelista , M. Feroci , A. Ferrari , M. Fiorini , T. Froysland , M. Frutti , F. Fuschino , M. Galli , F. Gianotti , A. Giuliani , C. Labanti , I. Lapshov , F. Lazzarotto , P. Lipari , F. Longo , M. Marisaldi , S. Mereghetti , A. Morselli , L. Pacciani , A. Pellizzoni , F. Perotti , G. Piano , P. Picozza , M. Pilia , G. Porrovecchio , M. Prest , M. Rapisarda , A. Rappoldi , A. Rubini , S. Sabatini , P. Soffitta , E. Striani , M. Trifoglio , A. Trois , E. Vallazza , A. Zambra , D. Zanello , I. Agudo , H. D. Aller , M. F. Aller , A. A. Arkharov , U. Bach , E. Benitez , A. Berdyugin , D. A. Blinov , C. S. Buemi , W. P. Chen , A. Di Paola , M. Dolci , E. Forne , L. Fuhrmann , J. L. Gomez , M. A. Gurwell , B. Jordan , S. G. Jorstad , J. Heidt , D. Hiriart , T. Hovatta , H. Y. Hsiao , G. Kimeridze , T. S. Konstantinova , E. N. Kopatskaya , E. Koptelova , O. M. Kurtanidze , S. O. Kurtanidze , V. M. Larionov , A. Lahteenmaki , P. Leto , E. Lindfors , A. P. Marscher , B. McBreen , I. M. McHardy , D. A. Morozova , K. Nilsson , M. Pasanen , M. Roca-Sogorb , A. Sillanpaa , L. O. Takalo , M. Tornikoski , C. Trigilio , I. S. Troitsky , G. Umana , L. A. Antonelli , S. Colafrancesco , C. Pittori , P. Santolamazza , F. Verrecchia , P. Giommi , L. Salotti

H.E.S.S. discovery of very-high-energy gamma-ray emission of PKS 1440-389

Blazars are the most abundant class of known extragalactic very-high-energy (VHE, E>100 GeV) gamma-ray sources. However, one of the biggest difficulties in investigating their VHE emission resides in their limited number, since less than 60…

High Energy Astrophysical Phenomena · Physics 2019-08-14 H. Prokoph , Y. Becherini , M. Böttcher , C. Boisson , J. -P. Lenain , I. Sushch

A Catalogue of Variable Active Galactic Nuclei Based on Multi-Timescale Variability Analysis from Fermi-LAT Data

Active Galactic Nuclei (AGN) sources feature supermassive black holes that launch relativistic plasma jets. They are key $\gamma$-ray sources providing a unique laboratory for studying extreme particle acceleration and plasma physics.…

High Energy Astrophysical Phenomena · Physics 2026-02-03 Luana Passos-Reis , Elisabete M. de Gouveia Dal Pino , Tarek Hassan , Santiago Pita , Alberto Domínguez

A re-emerging bright soft-X-ray state of the changing-look Active Galactic Nucleus 1ES~1927+654: a multi-wavelength view

1ES1927+654 is a nearby active galactic nucleus that has shown an enigmatic outburst in optical/UV followed by X-rays, exhibiting strange variability patterns at timescales of months-years. Here we report the unusual X-ray, UV, and radio…

High Energy Astrophysical Phenomena · Physics 2023-08-14 Ritesh Ghosh , Sibasish Laha , Eileen Meyer , Agniva Roychowdhury , Xiaolong Yang , J. A. Acosta Pulido , Suvendu Rakshit , Shivangi Pandey , Josefa Becerra Gonzalez , Ehud Behar , Luigi C. Gallo , Francesca Panessa , Stefano Bianchi , Fabio La Franca , Nicolas Scepi , Mitchell C. Begelman , Anna Lia Longinotti , Elisabeta Lusso , Samantha Oates , Matt Nicholl , S. Bradley Cenko , Brendan O Connor , Erica Hammerstein , Jincen Jose , Krisztina Eva Gabanyi , Federica Ricci , Sabyasachi Chattopadhyay