Related papers: Extreme TeV blazars and the intergalactic magnetic…

Discovery of hard-spectrum \gamma-ray emission from the BL Lac object 1ES 0414+009

1ES 0414+009 (z = 0.287) is a distant high-frequency-peaked BL Lac object, and has long been considered a likely emitter of very-high energy (VHE, E>100 GeV) gamma-rays due to its high X-ray and radio flux. Observations in the VHE gamma-ray…

High Energy Astrophysical Phenomena · Physics 2015-06-03 The HESS Collaboration , A. Abramowski , F. Acero , F. Aharonian , A. G. Akhperjanian , G. Anton , A. Balzer , A. Barnacka , U. Barres de Almeida , Y. Becherini , J. Becker , B. Behera , K. Bernlöhr , E. Birsin , J. Biteau , A. Bochow , C. Boisson , J. Bolmont , P. Bordas , J. Brucker , F. Brun , P. Brun , T. Bulik , I. Büsching , S. Carrigan , S. Casanova , M. Cerruti , P. M. Chadwick , A. Charbonnier , R. C. G. Chaves , A. Cheesebrough , L. -M. Chounet , A. C. Clapson , G. Coignet , G. Cologna , J. Conrad , M. Dalton , M. K. Daniel , I. D. Davids , B. Degrange , C. Deil , H. J. Dickinson , A. Djannati-Ataï , W. Domainko , L. O'C. Drury , F. Dubois , G. Dubus , K. Dutson , J. Dyks , M. Dyrda , K. Egberts , P. Eger , P. Espigat , L. Fallon , C. Farnier , F. Feinstein , M. V. Fernandes , A. Fiasson , G. Fontaine , A. Förster , M. Füßling , Y. A. Gallant , H. Gast , L. Gérard , D. Gerbig , B. Giebels , J. F. Glicenstein , B. Glück , P. Goret , D. Göring , S. Häffner , J. D. Hague , D. Hampf , M. Hauser , S. Heinz , G. Heinzelmann , G. Henri , G. Hermann , J. A. Hinton , A. Hoffmann , W. Hofmann , P. Hofverberg , M. Holler , D. Horns , A. Jacholkowska , O. C. de Jager , C. Jahn , M. Jamrozy , I. Jung , M. A. Kastendieck , K. Katarzynski , U. Katz , S. Kaufmann , D. Keogh , D. Khangulyan , B. Khélifi , D. Klochkov W. Kluźniak , T. Kneiske , Nu. Komin , K. Kosack , R. Kossakowski , H. Laffon , G. Lamanna , D. Lennarz , T. Lohse , A. Lopatin , C. -C. Lu , V. Marandon , A. Marcowith , J. Masbou , D. Maurin , N. Maxted , M. Mayer , T. J. L. McComb , M. C. Medina , J. Méhault , R. Moderski , E. Moulin , C. L. Naumann , M. Naumann-Godo , M. de Naurois , D. Nedbal , D. Nekrassov , N. Nguyen , B. Nicholas , J. Niemiec , S. J. Nolan , S. Ohm , E. de Ona Wilhelmi , B. Opitz , M. Ostrowski , I. Oya , M. Panter , M. Paz Arribas , G. Pedaletti , G. Pelletier , P. -O. Petrucci , S. Pita , G. Pühlhofer , M. Punch , A. Quirrenbach , M. Raue , S. M. Rayner , A. Reimer , 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 , V. Sahakian , D. A. Sanchez , A. Santangelo , R. Schlickeiser , F. M. Schöck , A. Schulz , U. Schwanke , S. Schwarzburg , S. Schwemmer , F. Sheidaei , M. Sikora , J. L. Skilton , H. Sol , G. Spengler , L. Stawarz , R. Steenkamp , C. Stegmann , F. Stinzing , K. Stycz , I. Sushch , A. Szostek , J. -P. Tavernet , R. Terrier , M. Tluczykont , K. Valerius , C. van Eldik , G. Vasileiadis , C. Venter , J. P. Vialle , A. Viana , P. Vincent , H. J. Völk , F. Volpe , S. Vorobiov , M. Vorster , S. J. Wagner , M. Ward , R. White , A. Wierzcholska , M. Zacharias , A. Zajczyk , A. A. Zdziarski , A. Zech , H. -S. Zechlin , L. Costamante , S. Fegan , M. Ajello

Evidence for a cosmological effect in \gamma-ray spectra of BL Lacs

We update the list of GeV-TeV extragalactic \gamma-ray sources using the 2-year catalog from the Fermi-LAT and recent results ground-based \gamma-ray telescopes. Breaks in the spectra between the high energy (100 MeV <E< 300 GeV) and the…

High Energy Astrophysical Phenomena · Physics 2013-06-05 D. A. Sanchez , S. Fegan , B. Giebels

TeV Blazars - Observations and Models

Since the first TeV blazar Markarian (Mrk) 421 was detected in 1992, the number of established TeV gamma-ray emitting BL Lac objects has grown to 6, with redshifts ranging from 0.031 (Mrk 421) to 0.129 (H 1426+428). The intensive study of…

Astrophysics · Physics 2008-11-26 Henric Krawczynski

Predicted Extragalactic TeV Gamma-Ray Sources

We suggest that low-redshift XBLs (X-ray selected BL Lacertae objects) may be the only extragalactic gamma-ray sources observable at TeV energies. We use simple physical considerations involving synchrotron and Compton component spectra for…

Astrophysics · Physics 2009-10-28 F. W. Stecker , O. C. De Jager , M. H. Salamon

The broad-band properties of the intermediate synchrotron peaked BL Lac S2 0109+22 from radio to VHE gamma rays

The MAGIC telescopes observed S2 0109+22 in 2015 July during its flaring activity in high energy gamma rays observed by Fermi-LAT. We analyse the MAGIC data to characterise the very high energy (VHE) gamma-ray emission of S2 0109+22, which…

High Energy Astrophysical Phenomena · Physics 2019-08-14 MAGIC Collaboration , S. Ansoldi , L. A. Antonelli , C. Arcaro , D. Baack , A. Babić , B. Banerjee , P. Bangale , U. Barres de Almeida , J. A. Barrio , J. Becerra González , W. Bednarek , E. Bernardini , R. Ch. Berse , A. Berti , J. Besenrieder , W. Bhattacharyya , C. Bigongiari , A. Biland , O. Blanch , G. Bonnoli , R. Carosi , G. Ceribella , A. Chatterjee , S. M. Colak , P. Colin , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , P. Cumani , V. D'Elia , 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. Fattorini , A. Fernández-Barral , G. Ferrara , D. Fidalgo , L. Foffano , M. V. Fonseca , L. Font , C. Fruck , S. Gallozzi , R. J. García López , M. Garczarczyk , M. Gaug , P. Giammaria , N. Godinović , D. Guberman , D. Hadasch , A. Hahn , T. Hassan , M. Hayashida , J. Herrera , J. Hoang , D. Hrupec , S. Inoue , K. Ishio , Y. Iwamura , Y. Konno , H. Kubo , J. Kushida , A. Lamastra , D. Lelas , F. Leone , 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 , 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 , P. Penil , M. Peresano , M. Persic , K. Pfrang , P. G. Prada Moroni , E. Prandini , I. Puljak , J. R. Garcia , W. Rhode , M. Ribó , J. Rico , C. Righi , A. Rugliancich , L. Saha , T. Saito , K. Satalecka , T. Schweizer , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Stamerra , M. Strzys , T. Surić , F. Tavecchio , P. Temnikov , T. Terzić , M. Teshima , N. Torres-Albà , S. Tsujimoto , G. Vanzo , M. Vazquez Acosta , I. Vovk , J. E. Ward , M. Will , D. Zarić , Fermi-LAT Collaboration , S. Ciprini , R. Desiante , MWL Collaborators , S. Barcewicz , T. Hovatta , J. Jormanainen , L. Takalo , R. Reinthal , F. Wierda , A. Lähteenmäki , J. Tammi , M. Tornikoski , R. J. C. Vera , S. Kiehlmann , W. Max-Moerbeck , A. C. S. Readhead

Detection of TeV Gamma-Rays from the BL Lac 1ES1959+650 in its low states and during a major outburst in 2002

TeV gamma-rays from the BL Lac object 1ES1959+650 have been measured during the years 2000 and 2001 with a significance of 5.2 sigma at a value of 5.3% of the Crab flux and in May 2002 during strong outbursts with > 23 sigma at a flux level…

Astrophysics · Physics 2007-05-23 HEGRA Collaboration , F. Aharonian , A. Akhperjanian , M. Beilicke

Hunting Very High-Energy ($>$100 GeV) Emitting High-Synchrotron Peaked Blazars

Very-high energy (VHE; $>$100 GeV) $\gamma$-ray emission originates via some of the most extreme particle acceleration processes in the universe. Considering beamed active galactic nuclei, i.e., blazars, only a small fraction, mainly high…

High Energy Astrophysical Phenomena · Physics 2025-12-10 Sushmita Agarwal , Vaidehi S. Paliya

A Three-Year Multi-Wavelength Study of the Very High Energy Gamma-ray Blazar 1ES 0229+200

The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Gamma ~ 2.5), very-high-energy-emitting (E > 100 GeV) gamma-ray blazar. Very-high-energy measurements of this active galactic…

High Energy Astrophysical Phenomena · Physics 2015-06-18 E. Aliu , S. Archambault , T. Arlen , T. Aune , B. Behera , M. Beilicke , W. Benbow , K. Berger , R. Bird , A. Bouvier , J. H. Buckley , V. Bugaev , K. Byrum , M. Cerruti , X. Chen , L. Ciupik , M. P. Connolly , W. Cui , C. Duke , J. Dumm , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , H. Fleischhack , P. Fortin , L. Fortson , A. Furniss , N. Galante , G. H. Gillanders , S. Griffin , S. T. Griffiths , J. Grube , G. Gyuk , D. Hanna , J. Holder , G. Hughes , T. B. Humensky , C. A. Johnson , P. Kaaret , M. Kertzman , Y. Khassen , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , K. Meagher , J. Millis , P. Moriarty , R. Mukherjee , D. Nieto , A. O'Faolain de Bhroithe , R. A. Ong , A. N. Otte , N. Park , J. S. Perkins , M. Pohl , A. Popkow , H. Prokoph , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , G. T. Richards , E. Roache , G. H. Sembroski , A. W. Smith , D. Staszak , I. Telezhinsky , M. Theiling , A. Varlotta , V. V. Vassiliev , S. Vincent , S. P. Wakely , T. C. Weekes , A. Weinstein , R. Welsing , D. A. Williams , A. Zajczyk , B. Zitzer

A decade of multi-wavelength observations of the TeV blazar 1ES 1215+303: Extreme shift of the synchrotron peak frequency and long-term optical-gamma-ray flux increase

Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and…

High Energy Astrophysical Phenomena · Physics 2020-03-23 Janeth Valverde , Deirdre Horan , Denis Bernard , Stephen Fegan , A. U. Abeysekara , A. Archer , W. Benbow , R. Bird , A. Brill , R. Brose , M. Buchovecky , J. H. Buckley , J. L. Christiansen , W. Cui , A. Falcone , Q. Feng , J. P. Finley , L. Fortson , A. Furniss , A. Gent , G. H. Gillanders , C. Giuri , O. Gueta , D. Hanna , T. Hassan , O. Hervet , J. Holder , G. Hughes , T. B. Humensky , P. Kaaret , N. Kelley-Hoskins , M. Kertzman , D. Kieda , M. Krause , F. Krennrich , M. J. Lang , G. Maier , P. Moriarty , R. Mukherjee , D. Nieto , M. Nievas-Rosillo , S. O'Brien , R. A. Ong , A. N. Otte , N. Park , A. Petrashyk , K. Pfrang , A. Pichel , M. Pohl , R. R. Prado , E. Pueschel , J. Quinn , K. Ragan , P. T. Reynolds , D. Ribeiro , G. T. Richards , E. Roache , I. Sadeh , M. Santander , S. S. Scott , G. H. Sembroski , K. Shahinyan , R. Shang , I. Sushch , V. V. Vassiliev , A. Weinstein , R. M. Wells , P. Wilcox , A. Wilhelm , D. A. Williams , T. J Williamson , Giuliana Noto , P. G. Edwards , B. G. Piner , V. Fallah Ramazani , T. Hovatta , J. Jormanainen , E. Lindfors , K. Nilsson , L. Takalo , Y. Y. Kovalev , M. L. Lister , A. B. Pushkarev , T. Savolainen , S. Kiehlmann , W. Max-Moerbeck , A. C. S. Readhead , A. Lähteenmäki , M. Tornikoski

Systematic search for VHE gamma-ray emission from X-ray bright high-frequency BL Lac objects

All but three (M87, BL Lac and 3C 279) extragalactic sources detected so far at very high energy (VHE) gamma-rays belong to the class of high-frequency peaked BL Lac (HBL) objects. This suggested to us a systematic scan of candidate sources…

Astrophysics · Physics 2019-08-12 M. Meyer

Multiwavelength Observations of Markarian 421 in March 2001: an Unprecedented View on the X-ray/TeV Correlated Variability

(Abridged) We present a detailed analysis of week-long simultaneous observations of the blazar Mrk421 at 2-60 keV X-rays (RXTE) and TeV gamma-rays (Whipple and HEGRA) in 2001. The unprecedented quality of this dataset enables us to…

Astrophysics · Physics 2008-06-16 G. Fossati , J. H. Buckley , I. H. Bond , S. M. Bradbury , D. A. Carter-Lewis , Y. C. K. Chow , W. Cui , A. D. Falcone , J. P. Finley , J. A. Gaidos , J. Grube , J. Holder , D. Horan , D. Horns , M. M. Jordan , D. B. Kieda , J. Kildea , H. Krawczynski , F. Krennrich , M. J. Lang , S. LeBohec , K. Lee , P. Moriarty , R. A. Ong , D. Petry , J. Quinn , G. H. Sembroski , S. P. Wakely , T. C. Weekes

The Highest Energy Emission Detected by EGRET from Blazars

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

The BeppoSAX view of extreme BL Lacs

With its very wide energy band (0.1-100 keV), BeppoSAX has played a fundamental role in the blazar field, allowing in particular a better study of the highest synchrotron peaked objects. Here we summarize the results of an observational…

Astrophysics · Physics 2007-05-23 L. Costamante , G. Ghisellini , A. Celotti , A. Wolter

Fermi/LAT observations of 1ES 0229+200: implications for extragalactic magnetic fields and background light

We report the observation in the GeV band of the blazar 1ES 0229+200, which over recent years has become one the primary sources used to put constraints on the Extragalactic Background Light (EBL) and Extragalactic Magnetic Field (EGMF). We…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Ievgen Vovk , Andrew M. Taylor , Dmitri Semikoz , Andrii Neronov

Derivation of a Relation for the Steepening of TeV Selected Blazar Gamma-ray Spectra with Energy and Redshift

We derive a relation for the steepening of blazar gamma-ray spectra between the multi-GeV Fermi energy range and the TeV energy range observed by atmospheric Cerenkov telescopes. The change in spectral index is produced by two effects: (1)…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-12 Floyd W. Stecker , Sean T. Scully

Extragalactic background light absorption signal in the 0.26-10 TeV spectra of blazars

Recent observations of the TeV gamma-ray spectra of the two closest active galactic nuclei (AGNs), Markarian 501 (Mrk 501) and Markarian 421 (Mrk 421), by the Whipple and HEGRA collaborations have stimulated efforts to estimate or limit the…

Astrophysics · Physics 2009-10-31 Vladimir V. Vassiliev

Long-term multi-band photometric monitoring of Mrk 501

Radio-to-TeV observations of the bright nearby (z=0.034) blazar Markarian 501 (Mrk 501), performed from December 2012 to April 2018, are used to study the emission mechanisms in its relativistic jet. We examined the multi-wavelength…

High Energy Astrophysical Phenomena · Physics 2021-12-01 Axel Arbet-Engels , Dominik Baack , Matteo Balbo , Adrian Biland , Thomas Bretz , Jens Buss , Daniela Dorner , Laura Eisenberger , Dominik Elsaesser , Dorothee Hildebrand , Roman Iotov , Adelina Kalenski , Karl Mannheim , Alison Mitchell , Dominik Neise , Maximilian Noethe , Aleksander Paravac , Wolfgang Rhode , Bernd Schleicher , Vitalii Sliusar , Roland Walter

Spectro-Polarimetric Observations of TeV Sources (SPOTS): First results

Blazars are jetted active galactic nuclei, with the jet aligned along the observer's line of sight. Their spectral energy distributions are dominated by non-thermal emission, with an underlying thermal component at optical/ultraviolet…

High Energy Astrophysical Phenomena · Physics 2026-05-07 J. Barnard , B. van Soelen , I. P. van der Westhuizen , M. Böttcher , A. Martin-Carrillo , H. M. Schutte , S. van der Merwe , M. Zacharias

Relentless multi-wavelength variability of Mrk 421 and Mrk 501

Mrk 421 and Mrk 501 are two close, bright and well-studied high-synchrotron-peaked blazars, which feature bright and persistent GeV and TeV emission. We use the longest and densest dataset of unbiased observations of these two sources,…

High Energy Astrophysical Phenomena · Physics 2021-08-19 Vitalii Sliusar , Axel Arbet-Engels , Dominik Baack , Matteo Balbo , Adrian Biland , Thomas Bretz , Jens Buss , Daniela Dorner , Laura Eisenberger , Dominik Elsaesser , Dorothee Hildebrand , Roman Iotov , Adelina Kalenski , Karl Mannheim , Alison Mitchell , Dominik Neise , Maximilian Noethe , Aleksander Paravac , Wolfgang Rhode , Bernd Schleicher , Roland Walter

Inverse Compton X-ray Emissions from TeV blazar Mrk421 during a Historical Low-Flux State Observed with NuSTAR

We report on the detection of excess hard X-ray emission from the TeV BL Lac object Mrk421 during the historical low-flux state of the source in January 2013. NuSTAR observations were conducted four times between MJD56294 and MJD56312 with…

High Energy Astrophysical Phenomena · Physics 2016-08-17 Jun Kataoka , Lukasz Stawarz