Related papers: X-ray Flares from Markarian 501

A model for delayed emission in a very-high energy gamma-ray flare in Markarian 501

Recently, the MAGIC collaboration reported evidence for a delay in the arrival times of photons of different energies during a gamma-ray flare from the blazar Markarian 501 on 2005 July 9. We apply a homogeneous synchrotron self-Compton…

Astrophysics · Physics 2009-11-05 W. Bednarek , R. M. Wagner

VHE gamma-ray observations of Markarian 501

Markarian 501, a nearby (z=0.033) X-ray selected BL Lacertae object, is a well established source of Very High Energy (VHE, E>=300 GeV) gamma rays. Dramatic variability in its gamma-ray emission on time-scales from years to as short as two…

Astrophysics · Physics 2007-05-23 Whipple Collaboration , A. C. Breslin , I. H. Bond , S. M. Bradbury , J. H. Buckley , A. M. Burdett , M. J. Carson , D. A. Carter-Lewis , M. Catanese , M. F. Cawley , S. Dunlea , M. D'Vali , D. J. Fegan , S. J. Fegan , J. P. Finley , J. A. Gaidos , T. A. Hall , A. M. Hillas , D. Horan , J. Kildea , J. Knapp , F. Krennrich , S. LeBohec , R. W. Lessard , C. Masterson , B. McKernan , J. Quinn , H. J. Rose , F. W. Samuelson , G. H. Sembroski , V. V. Vassiliev , T. C. Weekes

The extreme HBL behaviour of Markarian 501 during 2012

A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on…

High Energy Astrophysical Phenomena · Physics 2020-01-29 M. L. Ahnen , S. Ansoldi , L. A. Antonelli , C. Arcaro , A. Babić , B. Banerjee , P. Bangale , U. Barres de Almeida , J. A. Barrio , J. Becerra González , W. Bednarek , E. Bernardini , A. Berti , W. Bhattacharyya , O. Blanch , G. Bonnoli , R. Carosi , A. Carosi , 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 , M. Doert , A. Domínguez , D. Dominis Prester , M. Doro , D. Eisenacher Glawion , M. Engelkemeier , 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. Kuveždić , D. Lelas , E. Lindfors , S. Lombardi , F. Longo , M. López , C. Maggio , P. Majumdar , M. Makariev , G. Maneva , M. Manganaro , L. Maraschi , M. Mariotti , M. Martínez , D. Mazin , U. Menzel , 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 , L. Perri , M. Persic , P. G. Prada Moroni , E. Prandini , I. Puljak , J. R. Garcia , I. Reichardt , M. Ribó , J. Rico , C. Righi , A. Rugliancich , T. Saito , K. Satalecka , S. Schroeder , T. Schweizer , S. N. Shore , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Stamerra , M. Strzys , T. Surić , 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 , A. Arbet-Engels , D. Baack , M. Balbo , A. Biland , M. Blank , T. Bretz , K. Bruegge , M. Bulinski , J. Buss , A. Dmytriiev , D. Dorner , S. Einecke , D. Elsaesser , T. Herbst , D. Hildebrand , L. Kortmann , L. Linhoff , M. Mahlke , K. Mannheim , S. A. Mueller , D. Neise , A. Neronov , M. Noethe , J. Oberkirch , A. Paravac , W. Rhode , B. Schleicher , F. Schulz , K. Sedlaczek , A. Shukla , V. Sliusar , R. Walter , A. Archer , W. Benbow , R. Bird , R. Brose , J. H. Buckley , V. Bugaev , J. L. Christiansen , W. Cui , M. K. Daniel , A. Falcone , Q. Feng , J. P. Finley , G. H. Gillanders , O. Gueta , D. Hanna , O. Hervet , J. Holder , G. Hughes , M. Hütten , T. B. Humensky , C. A. Johnson , P. Kaaret , P. Kar , N. Kelley-Hoskins , M. Kertzman , D. Kieda , M. Krause , F. Krennrich , S. Kumar , M. J. Lang , T. T. Y. Lin , G. Maier , S. McArthur , P. Moriarty , R. Mukherjee , S. O'Brien , R. A. Ong , A. N. Otte , N. Park , A. Petrashyk , A. Pichel , M. Pohl , J. Quinn , K. Ragan , P. T. Reynolds , G. T. Richards , E. Roache , A. C. Rovero , C. Rulten , I. Sadeh , M. Santander , G. H. Sembroski , K. Shahinyan , I. Sushch , J. Tyler , S. P. Wakely , A. Weinstein , R. M. Wells , P. Wilcox , A. Wilhel , D. A. Williams , T. J Williamson , B. Zitzer , M. Perri , F. Verrecchia , C. Leto , M. Villata , C. M. Raiteri , S. G. Jorstad , V. M. Larionov , D. A. Blinov , T. S. Grishina , E. N. Kopatskaya , E. G. Larionova , A. A. Nikiforova , D. A. Morozova , Yu. V. Troitskaya , I. S. Troitsky , O. M. Kurtanidze , M. G. Nikolashvili , S. O. Kurtanidze , G. N. Kimeridze , R. A. Chigladze , A. Strigachev , A. C. Sadun , J. W. Moody , W. P. Chen , H. C. Lin , J. A. Acosta-Pulido , M. J. Arévalo , M. I. Carnerero , P. A. González-Morales , A. Manilla-Robles , H. Jermak , I. Steele , C. Mundel , E. Benítez , D. Hiriart , P. S. Smith , W. Max-Moerbeck , A. C. S. Readhead , J. L. Richards , T. Hovatta , A. Lähteenmäki , M. Tornikoski , J. Tammi , M. Georganopoulos , M. G. Baring

The TeV spectrum of Mkn 501 as measured during the high state in 1997 by the HEGRA stereoscopic system of imaging air Cherenkov telescopes

The BL Lac object Mkn 501 has shown very high emission in TeV gamma-rays from March to October, 1997. During this period the source was continuously monitored with the HEGRA stereoscopic system of 4 imaging air Cherenkov telescopes for a…

Astrophysics · Physics 2019-08-14 A. Konopelko

Study of long-term spectral evolution and X-ray and Gamma-ray correlation of blazars seen by HAWC

The HAWC Observatory collected 6 years of extensive data, providing an ideal platform for long-term monitoring of blazars in the Very High Energy (VHE) band, without bias towards specific flux states. HAWC continuously monitors blazar…

High Energy Astrophysical Phenomena · Physics 2025-01-28 R. Alfaro , C. Alvarez , A. Andrés , J. C. Arteaga-Velázquez , D. Avila Rojas , H. A. Ayala Solares , R. Babu , E. Belmont-Moreno , A. Bernal , K. S. Caballero-Mora , T. Capistrán , A. Carramiñana , F. Carreón , S. Casanova , U. Cotti , J. Cotzomi , S. Coutiño de León , E. De la Fuente , D. Depaoli , N. Di Lalla , R. Diaz Hernandez , B. L. Dingus , M. A. DuVernois , M. Durocher , J. C. Díaz-Vélez , K. Engel , C. Espinoza , K. L. Fan , N. Fraija , S. Fraija , J. A. García-González , F. Garfias , A. Gonzalez Muñoz , M. M. González , J. A. Goodman , S. Groetsch , J. P. Harding , S. Hernández-Cadena , I. Herzog , D. Huang , F. Hueyotl-Zahuantitla , A. Iriarte , V. Joshi , S. Kaufmann , D. Kieda , A. Lara , W. H. Lee , J. Lee , H. León Vargas , J. T. Linnemann , A. L. Longinotti , G. Luis-Raya , K. Malone , O. Martinez , I. Martinez-Castellanos , J. Martínez-Castro , J. A. Matthews , P. Miranda-Romagnoli , J. A. Montes , E. Moreno , M. Mostafá , A. Nayerhoda , L. Nellen , M. U. Nisa , R. Noriega-Papaqui , N. Omodei , M. Osorio , Y. Pérez Araujo , E. G. Pérez-Pérez , C. D. Rho , D. Rosa-González , E. Ruiz-Velasco , H. Salazar , D. Salazar-Gallegos , A. Sandoval , M. Schneider , J. Serna-Franco , A. J. Smith , Y. Son , R. W. Springer , O. Tibolla , K. Tollefson , I. Torres , R. Torres-Escobedo , R. Turner , F. Ureña-Mena , E. Varela , L. Villaseñor , X. Wang , I. J. Watson , K. Whitaker , E. Willox , S. Yun-Cárcamo , H. Zhou , C. de León , Abraham D. Falcone , Fredric Hancock

A brief (blazar oriented) overview on topics for multi-wavelength observations with TeV photons

Multi-wavelength observations with TeV photons are an essential diagnostic tool to study the physics of TeV sources. The complex variability of blazars, however (timescales from years down to minutes, with different patterns and SED…

Astrophysics · Physics 2009-11-10 L. Costamante

Observation of Markarian 421 in TeV gamma rays over a 14-year time span

The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m telescope. It is shown that the dynamic range of its flux variations is large and similar to that in X-rays. A…

High Energy Astrophysical Phenomena · Physics 2015-06-17 V. A. Acciari , T. Arlen , T. Aune , W. Benbow , R. Bird , A. Bouvier , S. M. Bradbury , J. H. Buckley , V. Bugaev , I. de la Calle Perez , D. A. Carter-Lewis , A. Cesarini , L. Ciupik , E. Collins-Hughes , M. P. Connolly , W. Cui , C. Duke , J. Dumm , A. Falcone , S. Federici , D. J. Fegan , S. J. Fegan , J. P. Finley , G. Finnegan , L. Fortson , J. Gaidos , N. Galante , D. Gall , K. Gibbs , G. H. Gillanders , S. Griffin , J. Grube , G. Gyuk , D. Hanna , D. Horan , T. B. Humensky , P. Kaaret , M. Kertzman , Y. Khassen , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , J. E. McEnery , A. S. Madhavan , P. Moriarty , T. Nelson , A. O'Faoláin de Bhróithe , R. A. Ong , M. Orr , A. N. Otte , J. S. Perkins , D. Petry , A. Pichel , M. Pohl , J. Quinn , K. Ragan , P. T. Reynolds , E. Roache , A. Rovero , M. Schroedter , G. H. Sembroski , A. Smith , I. Telezhinsky , M. Theiling , J. Toner , J. Tyler , A. Varlotta , M. Vivier , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , R. Welsing , D. A. Williams , S. Wissel

TeV blazar variability: the firehose instability?

Recently observed minute timescale variability of blazar emission at TeV energies has imposed severe constraints on jet models and TeV emission mechanisms. We focus on a robust jet instability to explain this variability. As a consequence…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Prasad Subramanian , Amit Shukla , Peter A. Becker

Rapid TeV Gamma-Ray Flaring of BL Lacertae

We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6-minute exposure,…

High Energy Astrophysical Phenomena · Physics 2015-06-12 T. Arlen , T. Aune , M. Beilicke , W. Benbow , A. Bouvier , J. H. Buckley , V. Bugaev , A. Cesarini , L. Ciupik , M. P. Connolly , W. Cui , R. Dickherber , J. Dumm , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , S. Griffin , J. Grube , G. Gyuk , D. Hanna , J. Holder , T. B. Humensky , P. Kaaret , N. Karlsson , M. Kertzman , Y. Khassen , D. Kieda , H. Krawczynski , F. Krennrich , G. Maier , P. Moriarty , R. Mukherjee , T. Nelson , A. O'Faolain de Bhroithe , R. A. Ong , M. Orr , N. Park , J. S. Perkins , A. Pichel , M. Pohl , H. Prokoph , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , D. B. Saxon , M. Schroedter , G. H. Sembroski , D. Staszak , I. Telezhinsky , G. Tesic , M. Theiling , K. Tsurusaki , A. Varlotta , S. Vincent , S. P. Wakely , T. C. Weekes , A. Weinstein , R. Welsing , D. A. Williams , B. Zitzer , S. G. Jorstad , N. R. MacDonald , A. P. Marscher , P. S. Smith , R. C. Walker , T. Hovatta , J. Richards , W. Max-Moerbeck , A. Readhead , M. L. Lister , Y. Y. Kovalev , A. B. Pushkarev , M. A. Gurwell , A. Lahteenmaki , E. Nieppola , M. Tornikoski , E. Jarvela

New Multiwavelength Observations of PKS 2155-304 and Implications for the Coordinated Variability Patterns of Blazars

The TeV blazar PKS 2155--304 was the subject of an intensive 2 week optical and near-infrared observing campaign in 2004 August with the CTIO 0.9m telescope. During this time, simultaneous X-ray data from RXTE were also obtained. We compare…

Astrophysics · Physics 2009-11-13 M. Angela Osterman , H. Richard Miller , Kevin Marshall , Wesley T. Ryle , Hugh Aller , Margo Aller , John P. McFarland

Photometric Flaring Fraction of M dwarf Stars from the SkyMapper Southern Survey

We present our search for flares from M dwarf stars in the SkyMapper Southern Survey DR1, which covers nearly the full Southern hemisphere with six-filter sequences that are repeatedly observed in the passbands $uvgriz$. This allows us to…

Solar and Stellar Astrophysics · Physics 2019-10-23 Seo-Won Chang , Christian Wolf , Christopher A. Onken

Observations of TeV gamma-rays from Mrk 421 during Dec. 2005 to Apr. 2006 with the TACTIC telescope

The TACTIC $\gamma$-ray telescope has observed Mrk 421 on 66 clear nights from Dec. 07, 2005 to Apr. 30, 2006, totalling $\sim$ 202 hours of on-source observations. Here, we report the detection of flaring activity from the source at $\geq$…

Astrophysics · Physics 2008-11-26 K. K. Yadav , P. Chandra , A. K. Tickoo , R. C. Rannot , S. Godambe , M. K. Koul , V. K. Dhar , S. Thoudam , N. Bhatt , S. Bhattacharyya , K. Chanchalani , H. C. Goyal , R. K. Kaul , M. Kothari , S. Kotwal , R. Koul , S. Sahayanathan , M. Sharma , K. Venugopal

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

ANTARES search for high-energy neutrinos from TeV-emitting blazars, Markarian 421 and 501, in coincidence with HAWC gamma-ray flares

An updated analysis of a targeted search for high-energy neutrinos from Markarian 421 and Markarian 501 is reported. They are two of the closest and brightest extragalactic sources in the TeV band. In contrast to other types of active…

High Energy Astrophysical Phenomena · Physics 2019-11-13 Mukharbek Organokov , Thierry Pradier

Long-term Fermi observations of Mrk 421: clues for different non-stationary processes

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

A report on the type II X-ray burst from SMC X-1

We study RXTE PCA data for the high mass X-ray binary source SMC X-1 between 2003-10 and 2003-12 when the source was in high states. The source is found to be frequently bursting which can be seen as flares in lightcurves on an average of…

High Energy Astrophysical Phenomena · Physics 2019-01-16 Binay Rai , Pragati Pradhan , Bikash Chandra Paul

Observations of the gamma-Ray Emission Above 250 Gev from the Blazars Markarian 501 and Markarian 421 by the Cat Cherenkov Atmospheric Imaging Telescope

The Very High Energy (VHE) gamma-ray emission of the closest BL Lacertae objects Markarian 501 and Markarian 421 has been observed by the CAT telescope in 1997 and 1998. In 1997 Mrk 501 exhibited a remarkable series of flares, with a VHE…

Astrophysics · Physics 2007-05-23 F. PIRON

Variations of the TeV energy spectrum at different flux levels of Mkn 421 observed with the HEGRA system of Cherenkov telescopes

The nearby BL Lacertae (BL Lac) object Markarian~421 (Mkn~421) at a red shift z=0.031 was observed to undergo strong TeV Gamma-ray outbursts in the observational periods from December 1999 until May 2001. The time averaged energy spectrum…

Astrophysics · Physics 2008-11-26 HEGRA Collaboration , F. Aharonian

X-ray Emission of Mkn 421: New Clues From Its Spectral Evolution. II. Spectral Analysis and Physical Constraints

Mkn 421 was repeatedly observed with BeppoSAX in 1997-1998. The source showed a very rich phenomenology, with remarkable spectral variability. This is the second of two papers presenting the results of a thorough temporal and spectral…

Astrophysics · Physics 2009-10-31 G. Fossati , A. Celotti , M. Chiaberge , Y. H. Zhang , L. Chiappetti , G. Ghisellini , L. Maraschi , F. Tavecchio , E. Pian , A. Treves

Radio to gamma-ray variability study of blazar S5 0716+714

We present the results of a series of radio, optical, X-ray and gamma-ray observations of the BL Lac object S50716+714 carried out between April 2007 and January 2011. The multi-frequency observations were obtained using several ground and…

High Energy Astrophysical Phenomena · Physics 2015-06-12 B. Rani , T. P. Krichbaum , L. Fuhrmann , M. Boettcher , B. Lott , H. D. Aller , M. F. Aller , E. Angelakis , U. Bach , D. Bastieri , A. D. Falcone , Y. Fukazawa , K. E. Gabanyi , A. C. Gupta , M. Gurwell , R. Itoh , K. S. Kawabata , M. Krips , A. A. Lähteenmäki , X. Liu , N. Marchili , W. Max-Moerbeck , I. Nestoras , E. Nieppola , G. Quintana-Lacaci , A. C. S. Readhead , J. L. Richards , M. Sasada , A. Sievers , K. Sokolovsky , M. Stroh , J. Tammi , M. Tornikoski , M. Uemura , H. Ungerechts , T. Urano , J. A. Zensus