Related papers: Exceptionally bright TeV flares from the binary LS…

TeV variability in blazars: how fast can it be?

Recent Cerenkov observations of the two BL Lac objects PKS 2155-304 and Mkn 501 revealed TeV flux variability by a factor ~2 in just 3-5 minutes. Even accounting for the effects of relativistic beaming, such short timescales are challenging…

Astrophysics · Physics 2009-11-13 G. Ghisellini , F. Tavecchio , G. Bodo , A. Celotti

An Exceptional VHE Gamma-Ray Flare of PKS 2155-304

The high-frequency peaked BL Lac PKS 2155-304 at redshift z=0.116 is a well-known VHE (>100 GeV) gamma-ray emitter. Since 2002 its VHE flux has been monitored using the H.E.S.S. stereoscopic array of imaging atmospheric-Cherenkov telescopes…

Astrophysics · Physics 2009-12-10 F. Aharonian

X-ray/UV/Optical follow-up of the blazar PKS 2155-304 after the giant TeV flares of July 2006

We present all the publicly available data, from optical/UV wavelengths (UVOT) to X-rays (XRT, BAT), obtained from Swift observations of the blazar PKS 2155-304, performed in response to the rapid alert sent out after the strong TeV…

Astrophysics · Physics 2009-11-13 L. Foschini , G. Ghisellini , F. Tavecchio , A. Treves , L. Maraschi , M. Gliozzi , C. M. Raiteri , M. Villata , E. Pian , G. Tagliaferri , G. Tosti , R. M. Sambruna , G. Malaguti , G. Di Cocco , P. Giommi

Discovery of Variability in the Very High Energy Gamma-Ray Emission of 1ES 1218+304 with VERITAS

We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ~6% of the…

High Energy Astrophysical Phenomena · Physics 2010-01-18 The VERITAS Collaboration , V. A. Acciari , E. Aliu , M. Beilicke , W. Benbow , D. Boltuch , M. Böttcher , S. M. Bradbury , V. Bugaev , K. Byrum , A. Cesarini , L. Ciupik , P. Cogan , W. Cui , R. Dickherber , C. Duke , A. Falcone , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , K. Gibbs , R. Guenette , G. H. Gillanders , S. Godambe , J. Grube , D. Hanna , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , S. LeBohec , G. Maier , S. McArthur , A. McCann , P. Moriarty , T. Nagai , R. A. Ong , A. N. Otte , D. Pandel , J. S. Perkins , A. Pichel , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , M. Schroedter , G. H. Sembroski , A. W. Smith , D. Steele , S. P. Swordy , M. Theiling , S. Thibadeau , V. V. Vassiliev , S. Vincent , S. P. Wakely , T. C. Weekes , A. Weinstein , T. Weisgarber , D. A. Williams

TeV Gamma-Ray Observations of the Galactic Center

We report a possible detection of TeV gamma-rays from the Galactic Center by the Whipple 10m gamma-ray telescope. Twenty-six hours of data were taken over an extended period from 1995 through 2003 resulting in a total significance of 3.7…

Astrophysics · Physics 2009-11-10 K. Kosack , the VERITAS Collaboration

A search for enhanced very high energy gamma-ray emission from the March 2013 Crab Nebula flare

In March 2013, a flaring episode from the Crab Nebula lasting ~2 weeks was detected by the Fermi-LAT (Large Area Telescope on board the Fermi Gamma-ray Space Telescope). VERITAS provides simultaneous observations throughout this period.…

High Energy Astrophysical Phenomena · Physics 2014-01-09 The VERITAS Collaboration , E. Aliu , S. Archambault , T. Aune , 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 , J. Dumm , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , 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 , P. Kaaret , M. Kertzman , Y. Khassen , D. Kieda , F. Krennrich , S. Kumar , M. J. Lang , M. Lyutikov , G. Maier , S. McArthur , A. McCann , K. Meagher , J. Millis , P. Moriarty , R. Mukherjee , A. O'Faolain de Bhroithe , R. A. Ong , A. N. Otte , J. S. Perkins , M. Pohl , A. Popkow , J. Quinn , K. Ragan , J. Rajotte , L. C. Reyes , P. T. Reynolds , G. T. Richards , E. Roache , G. H. Sembroski , F. Sheidaei , A. W. Smith , D. Staszak , I. Telezhinsky , M. Theiling , J. V. Tucci , J. Tyler , A. Varlotta , S. P. Wakely , T. C. Weekes , A. Weinstein , R. Welsing , D. A. Williams , A. Zajczyk , B. Zitzer

H.E.S.S. Observations of PKS 2155-304

The high-frequency peaked BL Lac PKS 2155-304 at redshift z=0.117 has been detected with high significance (~45 sigma) at energies greater than 160 GeV, using the H.E.S.S. stereoscopic array of imaging air-Cherenkov telescopes in Namibia. A…

Astrophysics · Physics 2012-08-27 The H. E. S. S. Collaboration , : , F. Aharonian

What caused the GeV flare of PSR B1259-63 ?

PSR B1259-63 is a gamma-ray binary system composed of a high spindown pulsar and a massive star. Non-thermal emission up to TeV energies is observed near periastron passage, attributed to emission from high energy e+e- pairs accelerated at…

High Energy Astrophysical Phenomena · Physics 2015-06-16 G. Dubus , B. Cerutti

Discovery of a new TeV gamma-ray source: VER J0521+211

We report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov telescope array. These observations were motivated by the discovery of a cluster of >30GeV…

High Energy Astrophysical Phenomena · Physics 2013-10-04 VERITAS Collaboration , S. Archambault , T. Arlen , T. Aune , M. Beilicke , W. Benbow , R. Bird , A. Bouvier , J. H. Buckley , V. Bugaev , K. Byrum , A. Cesarini , L. Ciupik , M. P. Connolly , W. Cui , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , L. Fortson , A. Furniss , N. Galante , D. Gall , G. H. Gillanders , S. Griffin , J. Grube , G. Gyuk , D. Hanna , J. Holder , G. Hughes , T. B. Humensky , P. Kaaret , M. Kertzman , Y. Khassen , D. Kieda , H. Krawczynski , F. Krennrich , S. Kumar , M. J. Lang , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , J. Millis , P. Moriarty , R. Mukherjee , 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 , D. B. Saxon , 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 , B. Zitzer , M. Bottcher , S. J. Fegan , P. Fortin , J. P. Halpern , Y. Y. Kovalev , M. L. Lister , J. Liu , A. B. Pushkarev , P. S. Smith

Discovery of High-Energy Gamma-Ray Emission from the Binary System PSR B1259-63/LS 2883 Around Periastron with Fermi

We report on the discovery of \geq 100 MeV {\gamma} rays from the binary system PSR B1259-63/LS 2883 using the Large Area Telescope (LAT) on board Fermi. The system comprises a radio pulsar in orbit around a Be star. We report on LAT…

High Energy Astrophysical Phenomena · Physics 2011-06-30 A. A. Abdo , Fermi LAT Collaboration , M. Chernyakova , A. Neronov , E. Grundstrom , the Fermi Pulsar Timing Consortium

On the formation of TeV radiation in LS 5039

The recent detections of TeV gamma-rays from compact binary systems show that relativistic outflows (jets or winds) are sites of effective acceleration of particles up to multi-TeV energies. In this paper, we discuss the conditions of…

Astrophysics · Physics 2009-11-13 Dmitry Khangulyan , Felix Aharonian , Valenti Bosch-Ramon

Discovery of VHE $\gamma$-ray emission from the SNR G54.1+0.3

We report the discovery of very high energy gamma-ray emission from the direction of the SNR G54.1+0.3 using the VERITAS ground-based gamma-ray observatory. The TeV signal has an overall significance of 6.8$\sigma$ and appears point-like…

High Energy Astrophysical Phenomena · Physics 2016-08-14 V. A. Acciari , E. Aliu , T. Arlen , T. Aune , M. Bautista , M. Beilicke , W. Benbow , D. Boltuch , S. M. Bradbury , J. H. Buckley , V. Bugaev , Y. Butt , K. Byrum , A. Cesarini , L. Ciupik , W. Cui , R. Dickherber , C. Duke , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , G. H. Gillanders , S. Godambe , E. V. Gotthelf , J. Grube , R. Guenette , G. Gyuk , D. Hanna , J. Holder , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , A. Konopelko , H. Krawczynski , F. Krennrich , M. J. Lang , S. LeBohec , G. Maier , S. McArthur , A. McCann , M. McCutcheon , P. Moriarty , R. Muhkerjee , R. A. Ong , A. N. Otte , D. Pandel , J. S. Perkins , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , M. Schroedter , G. H. Sembroski , G. Demet Senturk , P. Slane , A. W. Smith , D. Steele , S. P. Swordy , G. Těsić , M. Theiling , S. Thibadeau , V. V. Vassiliev , S. Vincent , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , T. Weisgarber , D. A. Williams , S. Wissel , M. Wood , B. Zitzer

H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883

PSR B1259-63 is a gamma-ray binary system that hosts a pulsar in an eccentric orbit, with a 3.4 year period, around an O9.5Ve star. At orbital phases close to periastron passages, the system radiates bright and variable non-thermal…

High Energy Astrophysical Phenomena · Physics 2024-06-27 H. E. S. S. Collaboration , F. Aharonian , F. Ait Benkhali , J. Aschersleben , H. Ashkar , M. Backes , V. Barbosa Martins , R. Batzofin , Y. Becherini , D. Berge , K. Bernlöhr , M. Böttcher , C. Boisson , J. Bolmont , M. de Bony de Lavergne , J. Borowska , M. Bouyahiaoui , R. Brose , A. Brown , F. Brun , B. Bruno , T. Bulik , C. Burger-Scheidlin , S. Caroff , S. Casanova , J. Celic , M. Cerruti , T. Chand , S. Chandra , A. Chen , J. Chibueze , O. Chibueze , G. Cotter , J. Damascene Mbarubucyeye , J. Devin , J. Djuvsland , A. Dmytriiev , K. Egberts , S. Einecke , J. -P. Ernenwein , G. Fontaine , S. Funk , S. Gabici , Y. A. Gallant , D. Glawion , J. F. Glicenstein , P. Goswami , G. Grolleron , L. Haerer , B. Heß , W. Hofmann , T. L. Holch , M. Holler , Zhiqiu Huang , M. Jamrozy , F. Jankowsky , V. Joshi , I. Jung-Richardt , E. Kasai , K. Katarzyński , D. Khangulyan , R. Khatoon , B. Khélifi , W. Kluźniak , Nu. Komin , K. Kosack , D. Kostunin , A. Kundu , R. G. Lang , S. Le Stum , F. Leitl , A. Lemière , M. Lemoine-Goumard , J. -P. Lenain , F. Leuschner , J. Mackey , D. Malyshev , G. Martí-Devesa , R. Marx , A. Mehta , P. J. Meintjes , A. Mitchell , R. Moderski , L. Mohrmann , A. Montanari , E. Moulin , T. Murach , M. de Naurois , J. Niemiec , S. Ohm , E. de Ona Wilhelmi , M. Ostrowski , S. Panny , M. Panter , R. D. Parsons , U. Pensec , G. Peron , D. A. Prokhorov , G. Pühlhofer , M. Punch , A. Quirrenbach , M. Regeard , A. Reimer , O. Reimer , I. Reis , H. Ren , F. Rieger , B. Rudak , E. Ruiz-Velasco , V. Sahakian , H. Salzmann , A. Santangelo , M. Sasaki , J. Schäfer , F. Schüssler , H. M. Schutte , J. N. S. Shapopi , S. Spencer , Ł. Stawarz , R. Steenkamp , S. Steinmassl , C. Steppa , K. Streil , I. Sushch , T. Takahashi , T. Tanaka , A. M. Taylor , R. Terrier , C. Thorpe-Morgan , M. Tluczykont , T. Unbehaun , C. van Eldik , B. van Soelen , M. Vecchi , C. Venter , J. Vink , T. Wach , S. J. Wagner , F. Werner , A. Wierzcholska , M. Zacharias , A. A. Zdziarski , A. Zech , N. Żywucka

Discovery of Spectral Variability of Markarian 421 at TeV Energies

The detection of spectral variability of the gamma-ray blazar Mrk 421 at TeV energies is reported. Observations with the Whipple Observatory 10m gamma-ray telescope taken in 2000/2001 revealed exceptionally strong and long-lasting flaring…

Astrophysics · Physics 2009-11-07 F. Krennrich , I. H. Bond , S. M. Bradbury , J. H. Buckley , D. A. Carter-Lewis , W. Cui , I. de la Calle Perez , D. J. Fegan , S. J. Fegan , J. P. Finley , J. A. Gaidos , K. Gibbs , G. H. Gillanders , T. A. Hall , A. M. Hillas , J. Holder , D. Horan , M. Jordan , M. Kertzman , D. Kieda , J. Kildea , J. Knapp , K. Kosack , M. J. Lang , S. LeBohec , P. Moriarty , D. Müller , R. A. Ong , R. Pallassini , D. Petry , J. Quinn , N. W. Reay , P. T. Reynolds , H. J. Rose , G. H. Sembroski , R. Sidwell , N. Stanton , S. P. Swordy , V. V. Vassiliev , S. P. Wakely , T. C. Weekes

Flares in the Crab Nebula Driven by Untwisting Magnetic Fields

The recent discovery of PeV electrons from the Crab nebula, produced on rapid time scales of one day or less with a sharply peaked gamma-ray spectrum without hard X-rays, challenges traditional models of diffusive shock acceleration…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Peter Sturrock , Markus J. Aschwanden

Evidence for long-term Gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057

HESS J0632+057 is one of only two unidentified very-high-energy gamma-ray sources which appear to be point-like within experimental resolution. It is possibly associated with the massive Be star MWC 148 and has been suggested to resemble…

High Energy Astrophysical Phenomena · Physics 2011-02-11 VERITAS Collaboration , V. A. Acciari , E. Aliu , T. Arlen , M. Beilicke , W. Benbow , D. Boltuch , S. M. Bradbury , J. H. Buckley , V. Bugaev , K. Byrum , A. Cannon , A. Cesarini , A. Cesarini , Y. C. Chow , L. Ciupik , P. Cogan , R. Dickherber , C. Duke , T. Ergin , A. Falcone , S. J. Fegan , J. P. Finley , G. Finnegan , P. Fortin , L. Fortson , A. Furniss , K. Gibbs , G. H. Gillanders , J. Grube , R. Guenette , G. Gyuk , D. Hanna , J. Holder , D. Horan , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , J. Kildea , A. Konopelko , H. Krawczynski , F. Krennrich , M. J. Lang , S. LeBohec , G. Maier , A. McCann , M. McCutcheon , J. Millis , P. Moriarty , R. Mukherjee , R. A. Ong , A. N. Otte , D. Pandel , J. S. Perkins , D. Petry , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , H. J. Rose , M. Schroedter , G. H. Sembroski , A. W. Smith , D. Steele , M. Theiling , J. A. Toner , A. Varlotta , V. V. Vassiliev , S. Vincent , R. G. Wagner , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , T. Weisgarber , D. A. Williams , S. Wissel , M. Wood

LS I+61 303: microquasar or not microquasar?

LS I +61 303 is a puzzling object detected from radio up to high-energy gamma-rays. Variability has recently been observed in its high-energy emission. The object is a binary system, with a compact object and a Be star as primary. The…

Astrophysics · Physics 2009-06-23 G. E. Romero , M. Orellana , A. T. Okazaki , S. P. Owocki

The Be/X-ray binary A0535+26 during its recent 2009/2010 outbursts

The Be/X-ray binary A0535+26 showed a giant outburst in December 2009 that reached ~5.14 Crab in the 15-50 keV range. Unfortunately, due to Sun constraints it could not be observed by most X-ray satellites. The outburst was preceded by four…

High Energy Astrophysical Phenomena · Physics 2011-07-19 I. Caballero , K. Pottschmidt , A. Santangelo , L. Barragan , D. Klochkov , C. Ferrigno , J. Rodriguez , P. Kretschmar , S. Suchy , D. M. Marcu , D. Mueller , J. Wilms , I. Kreykenbohm , R. E. Rothschild , R. Staubert , M. H. Finger , A. Camero-Arranz , K. Makishima , T. Mihara , M. Nakajima , T. Enoto , W. Iwakiri , Y. Terada

A Spectacular VHE Gamma-Ray Outburst from PKS 2155-304 in 2006

Since 2002 the VHE (>100 GeV) gamma-ray flux of the high-frequency peaked BL Lac PKS 2155-304 has been monitored with the High Energy Stereoscopic System (HESS). An extreme gamma-ray outburst was detected in the early hours of July 28, 2006…

Astrophysics · Physics 2007-10-01 W. Benbow , C. Boisson , L. Costamante , O. de Jager , G. Dubus , D. Emmanoulopoulos , B. Giebels , S. Pita , M. Punch , C. Raubenheimer , M. Raue , H. Sol , S. Wagner

Long-term multiwavelength observations of 1ES 1218+304: physical implications of the flux and spectral variability

This paper presents the results of a detailed timing and spectral analysis of the TeV-detected blazar 1ES 1218+304, focused on the observations performed with the different instruments onboard the Neil Gehrels Swift Observatory in the…

Astrophysics of Galaxies · Physics 2025-04-22 B. Kapanadze , A. Gurchumelia , M. Aller