Related papers: Dissecting the long-term emission behaviour of the…

A Multi-wavelength View of the TeV Blazar Markarian 421: Correlated Variability, Flaring, and Spectral Evolution

We report results from a multi-wavelength monitoring campaign on Mrk 421 over the period of 2003-2004. The source was observed simultaneously at TeV and X-ray energies, with supporting observations frequently carried out at optical and…

Astrophysics · Physics 2008-11-26 M. Blazejowski

20 years of monitoring: PKS 2155-304 and PKS 1510-089 in the eyes of Swift and Fermi. I. The case of PKS 2155-304

We present a comprehensive 20-year multiwavelength variability study of the blazar PKS 2155-304, one of the most luminous and extensively monitored high-frequency-peaked BL Lac objects in the southern hemisphere. Using Fermi-LAT…

High Energy Astrophysical Phenomena · Physics 2026-04-02 A. Wierzcholska , M. Zacharias

Not so Swift: 20 years of multiwavelength observations of Mrk 421 and Mrk 501

Aims. The blazars Mrk 421 and Mrk 501 have shown multiwavelength variability on all observed timescales, and have been well studied at high energies on short timescales. We aim to characterise the long-term temporal behaviour of these…

High Energy Astrophysical Phenomena · Physics 2026-02-25 Gabrielle L. Taylor , Stefan J. Wagner , Alicja Wierzcholska , Michael Zacharias

A time dependent approach to model X-ray and $\gamma$--ray light curves of Mrk 421 observed during the flare in February 2010

Strong X-ray and $\gamma$--ray flares have been detected in February 2010 from the high synchrotron peaked blazar Mrk 421 (z=0.031). With the motivation of understanding the physics involved in this flaring activity, we study the…

High Energy Astrophysical Phenomena · Physics 2017-01-11 K K Singh , S Sahayanathan , A Sinha , N Bhatt , A K Tickoo , K K Yadav , R C Rannot , P Chandra , K Venugopal , P Marandi , N Kumar , H C Goyal , A Goyal , N K Agarwal , M Kothari , K Chanchalani , V K Dhar , N Chouhan , C K Bhat , M K Koul , R Koul

Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and $\gamma$-ray activity in 2015$-$2016

We report a characterization of the multi-band flux variability and correlations of the nearby (z=0.031) blazar Markarian 421 (Mrk 421) using data from Mets\"{a}hovi, Swift, Fermi-LAT, MAGIC, FACT and other collaborations and instruments…

High Energy Astrophysical Phenomena · Physics 2021-05-26 MAGIC Collaboration , V. A. Acciari , S. Ansoldi , L. A. Antonelli , K. Asano , A. Babić , B. Banerjee , A. Baquero , U. Barres de Almeida , J. A. Barrio , J. Becerra González , W. Bednarek , L. Bellizzi , E. Bernardini , M. Bernardos , A. Berti , J. Besenrieder , W. Bhattacharyya , C. Bigongiari , O. Blanch , G. Bonnoli , Ž. Bošnjak , G. Busetto , R. Carosi , G. Ceribella , M. Cerruti , Y. Chai , A. Chilingarian , S. Cikota , S. M. Colak , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , G. D'Amico , V. D'Elia , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , M. Delfino , J. Delgado , C. Delgado Mendez , D. Depaoli , T. Di Girolamo , F. Di Pierro , L. Di Venere , E. Do Souto Espiñeira , D. Dominis Prester , A. Donini , M. Doro , V. Fallah Ramazani , A. Fattorini , G. Ferrara , L. Foffano , M. V. Fonseca , L. Font , C. Fruck , S. Fukami , R. J. García López , M. Garczarczyk , S. Gasparyan , M. Gaug , N. Giglietto , F. Giordano , P. Gliwny , N. Godinović , J. G. Green , D. Green , D. Hadasch , A. Hahn , L. Heckmann , J. Herrera , J. Hoang , D. Hrupec , M. Hütten , T. Inada , S. Inoue , K. Ishio , Y. Iwamura , J. Jormanainen , L. Jouvin , Y. Kajiwara , M. Karjalainen , D. Kerszberg , Y. Kobayashi , H. Kubo , J. Kushida , A. Lamastra , D. Lelas , F. Leone , E. Lindfors , S. Lombardi , F. Longo , M. López , R. López-Coto , A. López-Oramas , S. Loporchio , B. Machado de Oliveira Fraga , C. Maggio , P. Majumdar , M. Makariev , M. Mallamaci , G. Maneva , M. Manganaro , L. Maraschi , M. Mariotti , M. Martínez , D. Mazin , S. Mender , S. Mićanović , D. Miceli , T. Miener , M. Minev , J. M. Miranda , R. Mirzoyan , E. Molina , A. Moralejo , D. Morcuende , V. Moreno , E. Moretti , P. Munar-Adrover , V. Neustroev , C. Nigro , K. Nilsson , D. Ninci , K. Nishijima , K. Noda , S. Nozaki , Y. Ohtani , T. Oka , J. Otero-Santos , M. Palatiello , D. Paneque , R. Paoletti , J. M. Paredes , L. Pavletić , P. Peñil , C. Perennes , M. Persic , P. G. Prada Moroni , E. Prandini , C. Priyadarshi , I. Puljak , W. Rhode , M. Ribó , J. Rico , C. Righi , A. Rugliancich , L. Saha , N. Sahakyan , T. Saito , S. Sakurai , K. Satalecka , B. Schleicher , K. Schmidt , T. Schweizer , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Spolon , A. Stamerra , D. Strom , M. Strzys , Y. Suda , T. Surić , M. Takahashi , F. Tavecchio , P. Temnikov , T. Terzić , M. Teshima , N. Torres-Albà , L. Tosti , S. Truzzi , J. van Scherpenberg , G. Vanzo , M. Vazquez Acosta , S. Ventura , V. Verguilov , C. F. Vigorito , V. Vitale , I. Vovk , M. Will , D. Zarić , FACT collaboration , : , A. Arbet-Engels , D. Baack , M. Balbo , M. Beck , N. Biederbeck , A. Biland , T. Bretz , K. Bruegge , J. Buss , D. Dorner , D. Elsaesser , D. Hildebrand , R. Iotov , M. Klinger , K. Mannheim , D. Neise , A. Neronov , M. Noethe , A. Paravac , W. Rhode , B. Schleicher , V. Sliusar , F. Theissen , R. Walter , MWL Collaborators , : , J. Valverde , D. Horan , M. Giroletti , M. Perri , F. Verrecchia , C. Leto , A. C. Sadun , J. W. Moody , M. Joner , A. P. Marscher , S. G. Jorstad , A. Lähteenmäki , M. Tornikoski , V. Ramakrishnan , E. Järvelä , R. J. C. Vera , S. Righini , A. Y. Lien

The awakening of BL Lacertae: observations by Fermi, Swift, and the GASP-WEBT

Since the launch of the Fermi satellite, BL Lacertae has been moderately active at gamma-rays and optical frequencies until May 2011, when the source started a series of strong flares. The exceptional optical sampling achieved by the…

High Energy Astrophysical Phenomena · Physics 2019-08-14 C. M. Raiteri , M. Villata , F. D'Ammando , V. M. Larionov , M. A. Gurwell , D. O. Mirzaqulov , P. S. Smith

An emergence of new polarized emission region in blazar Mrk 421 associated with X-ray flare

We report on long-term multi-wavelength monitoring of blazar Mrk~421 from 2010 to 2011. The source exhibited extreme X-ray flares in 2010. Our research group performed optical photopolarimetric follow-up observations using the Kanata…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Ryosuke Itoh , Yasushi Fukazawa , Yasuyuki T. Tanaka , Koji S. Kawabata , Katsutoshi Takaki , Kazuma Hayashi , Makoto Uemura , Takahiro Ui , Mahito Sasada , Masayuki Yamanaka , Michitoshi Yoshida

The Optical Polarization Variability of PKS 2155-304: Correlations at Low and High Energies

Gamma-ray emitting blazars have been the targets of many recent or ongoing monitoring programmes. The resulting multi-wavelength data archives are ideal for studying the quiescent and variable behaviour of the blazar PKS 2155-304. Here,…

High Energy Astrophysical Phenomena · Physics 2017-02-15 Nikki Pekeur , Russ Taylor , Renée Kraan-Korteweg

An active state of the BL Lac Object Markarian 421 detected by INTEGRAL in April 2013

Multiwavelength variability of blazars offers indirect insight into their powerful engines and on the mechanisms through which energy is propagated from the centre down the jet. The BL Lac object Mkn 421 is a TeV emitter, a bright blazar at…

High Energy Astrophysical Phenomena · Physics 2014-10-22 E. Pian , M. Tuerler , M. Fiocchi , R. Boissay , A. Bazzano , L. Foschini , F. Tavecchio , V. Bianchin , G. Castignani , C. Ferrigno , C. M. Raiteri , M. Villata , V. Beckmann , F. D'Ammando , R. Hudec , G. Malaguti , L. Maraschi , T. Pursimo , P. Romano , S. Soldi , A. Stamerra , A. Treves , P. Ubertini , S. Vercellone , R. Walter

Long-term study of Mkn 421 with the HAGAR Array of Telescopes

Context:The HAGAR Telescope Array at Hanle, Ladakh has been regularly monitoring the nearby blazar Mkn 421 for the past 7yrs. Aims: Blazars show flux variability in all timescales across the electromagnetic spectrum. While there is abundant…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Atreyee Sinha , Amit Shukla , Lab Saha , B. S. Acharya , G. C. Anupama , P. Bhattacharya , R. J. Britto , V. R. Chitnis , T. P. Prabhu , B. B. Singh , P. R. Vishwanath

Very Long Baseline polarimetry and the gamma-ray connection in Markarian 421 during the broadband campaign in 2011

We analyzed data in polarized intensity obtained with the Very Long Baseline Array (VLBA) at twelve epochs (one observation per month from January to December 2011) at 15, 24, and 43 GHz. For the absolute orientation of the electric vector…

High Energy Astrophysical Phenomena · Physics 2014-11-11 R. Lico , M. Giroletti , M. Orienti , G. Giovannini , J. L. Gomez , C. Casadio , F. D'Ammando , M. G. Blasi , W. Cotton , P. G. Edwards , L. Fuhrmann , S. Jorstad , M. Kino , Y. Y. Kovalev , T. P. Krichbaum , A. P. Marscher , D. Paneque , G. Piner , K. Sokolovsky

Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and $\gamma$-ray brightness levels

In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and $\gamma$-ray bands. We present optical photometric and polarimetric data acquired by the Whole Earth…

High Energy Astrophysical Phenomena · Physics 2023-10-18 C. M. Raiteri , M. Villata , M. I. Carnerero , S. S. Savchenko , S. O. Kurtanidze , V. V. Vlasyuk , A. Marchini , K. Matsumoto , C. Lorey , M. D. Joner , K. Gazeas , D. Carosati , D. O. Mirzaqulov , J. A. Acosta Pulido , I. Agudo , R. Bachev , E. Benítez , G. A. Borman , P. Calcidese , W. P. Chen , G. Damljanovic , S. A. Ehgamberdiev , D. Elsässer , M. Feige , A. Frasca , H. Gaur , T. S. Grishina , A. C. Gupta , D. Hiriart , M. Holland , B. Horst , S. Ibryamov , R. Z. Ivanidze , J. Jensen , V. Jithesh , M. D. Jovanovic , S. Kiehlmann , G. N. Kimeridze , S. Kishore , E. N. Kopatskaya , O. M. Kurtanidze , E. G. Larionova , H. C. Lin , K. Mannheim , C. Marinelli , J. Moreira Reyes , D. A. Morozova , M. G. Nikolashvili , D. Reinhart , F. D. Romanov , E. Semkov , J. Seufert , E. V. Shishkina , L. A. Sigua , R. Skalidis , O. I. Spiridonova , M. Stojanovic , A. Strigachev , Y. V. Troitskaya , I. S. Troitskiy , A. Tsai , A. A. Vasilyev , O. Vince , K. Vrontaki , K. Wani , D. Watts , A. V. Zhovtan

Optical polarization properties of February 2010 outburst of the blazar Mrk 421

In this paper, we explore the behavior of optical polarization during the multi-wavelength outburst of the blazar Mrk 421 detected in February 2010. We use optical polarization measurements in the wavelength range 500-700 nm from SPOL…

High Energy Astrophysical Phenomena · Physics 2019-05-29 K K Singh , P J Meintjes , B van Soelen , F A Ramamonjisoa , B Vaidya

Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux correlations. The dataset has been collected through an…

High Energy Astrophysical Phenomena · Physics 2021-12-01 MAGIC Collaboration , V. A. Acciari , S. Ansoldi , L. A. Antonelli , A. Arbet Engels , M. Artero , K. Asano , A. Babić , A. Baquero , U. Barres de Almeida , J. A. Barrio , I. Batković , J. Becerra González , W. Bednarek , L. Bellizzi , E. Bernardini , M. Bernardos , A. Berti , J. Besenrieder , W. Bhattacharyya , C. Bigongiari , O. Blanch , Ž. Bošnjak , G. Busetto , R. Carosi , G. Ceribella , M. Cerruti , Y. Chai , A. Chilingarian , S. Cikota , S. M. Colak , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , G. D'Amico , V. D'Elia , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , M. Delfino , J. Delgado , C. Delgado Mendez , D. Depaoli , F. Di Pierro , L. Di Venere , E. Do Souto Espiñeira , D. Dominis Prester , A. Donini , M. Doro , V. Fallah Ramazani , A. Fattorini , G. Ferrara , M. V. Fonseca , L. Font , C. Fruck , S. Fukami , R. J. García López , M. Garczarczyk , S. Gasparyan , M. Gaug , N. Giglietto , F. Giordano , P. Gliwny , N. Godinović , J. G. Green , D. Green , D. Hadasch , A. Hahn , L. Heckmann , J. Herrera , J. Hoang , D. Hrupec , M. Hütten , T. Inada , S. Inoue , K. Ishio , Y. Iwamura , I. Jiménez , J. Jormanainen , L. Jouvin , Y. Kajiwara , M. Karjalainen , D. Kerszberg , Y. Kobayashi , H. Kubo , J. Kushida , A. Lamastra , D. Lelas , F. Leone , E. Lindfors , S. Lombardi , F. Longo , R. López-Coto , M. López-Moya , A. López-Oramas , S. Loporchio , B. Machado de Oliveira Fraga , C. Maggio , P. Majumdar , M. Makariev , M. Mallamaci , G. Maneva , M. Manganaro , L. Maraschi , M. Mariotti , M. Martínez , D. Mazin , S. Menchiari , S. Mender , S. Mićanović , D. Miceli , T. Miener , M. Minev , J. M. Miranda , R. Mirzoyan , E. Molina , A. Moralejo , D. Morcuende , V. Moreno , E. Moretti , V. Neustroev , C. Nigro , K. Nilsson , K. Nishijima , K. Noda , S. Nozaki , Y. Ohtani , T. Oka , J. Otero-Santos , S. Paiano , M. Palatiello , D. Paneque , R. Paoletti , J. M. Paredes , L. Pavletić , P. Peñil , C. Perennes , M. Persic , P. G. Prada Moroni , E. Prandini , C. Priyadarshi , I. Puljak , M. Ribó , J. Rico , C. Righi , A. Rugliancich , L. Saha , N. Sahakyan , T. Saito , S. Sakurai , K. Satalecka , F. G. Saturni , K. Schmidt , T. Schweizer , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Spolon , A. Stamerra , D. Strom , M. Strzys , Y. Suda , T. Surić , M. Takahashi , F. Tavecchio , P. Temnikov , T. Terzić , M. Teshima , L. Tosti , S. Truzzi , A. Tutone , S. Ubach , J. van Scherpenberg , G. Vanzo , M. Vazquez Acosta , S. Ventura , V. Verguilov , C. F. Vigorito , V. Vitale , I. Vovk , M. Will , C. Wunderlich , D. Zarić , FACT Collaboration , : , D. Baack , M. Balbo , N. Biederbeck , A. Biland , T. Bretz , J. Buss , D. Dorner , L. Eisenberger , D. Elsaesser , D. Hildebrand , R. Iotov , K. Mannheim , D. Neise , M. Noethe , A. Paravac , W. Rhode , B. Schleicher , V. Sliusar , R. Walter , Other groups , collaborations , : , F. D'Ammando , D. Horan , A. Y. Lien , M. Baloković , G. M. Madejski , M. Perri , F. Verrecchia , C. Leto , A. Lähteenmäki , M. Tornikoski , V. Ramakrishnan , E. Järvelä , R. J. C. Vera , M. Villata , C. M. Raiteri , A. C. Gupta , A. Pandey , A. Fuentes , I. Agudo , C. Casadio , E. Semkov , S. Ibryamov , A. Marchini , R. Bachev , A. Strigachev , E. Ovcharov , V. Bozhilov , A. Valcheva , E. Zaharieva , G. Damljanovic , O. Vince , V. M. Larionov , G. A. Borman , T. S. Grishina , V. A. Hagen-Thorn , E. N. Kopatskaya , E. G. Larionova , L. V. Larionova , D. A. Morozova , A. A. Nikiforova , S. S. Savchenko , I. S. Troitskiy , Y. V. Troitskaya , A. A. Vasilyev , O. A. Merkulova , W. P. Chen , M. Samal , H. C. Lin , J. W. Moody , A. C. Sadun , S. G. Jorstad , A. P. Marscher , Z. R. Weaver , M. Feige , J. Kania , M. Kopp , L. Kunkel , D. Reinhart , A. Scherbantin , L. Schneider , C. Lorey , J. A. Acosta-Pulido , M. I. Carnerero , D. Carosati , S. O. Kurtanidze , O. M. Kurtanidze , M. G. Nikolashvili , R. G. Chanishvili , R. A. Chigladze , R. Z. Ivanidze , G. N. Kimeridze , L. A. Sigua , M. D. Joner , M. Spencer , M. Giroletti , N. Marchili , S. Righini , N. Rizzi , G. Bonnoli

Multiwavelength Observations of the Blazar Mrk 421 in December 2002 and January 2003

We report on a multiwavelength campaign on the TeV gamma-ray blazar Markarian (Mrk) 421 performed during December 2002 and January 2003. These target of opportunity observations were initiated by the detection of X-ray and TeV gamma-ray…

Astrophysics · Physics 2019-08-15 P. Rebillot , M. Aller , H. Aller , P. Boltwood , I. Jung , D. Kranich , A. Sillanpaa , A. Sadun

The blazar 3C 454.3 was revealed by the Fermi Gamma-ray Space Telescope to be in an exceptionally high flux state in July 2008. Accordingly, we performed a multi-wavelength monitoring campaign on this blazar using IR and optical…

Astrophysics · Physics 2011-02-11 E. W. Bonning , C. Bailyn , C. M. Urry , M. Buxton , G. Fossati , L. Maraschi , P. Coppi , R. Scalzo , J. Isler , A. Kaptur

Long-term optical polarization variability and multiwavelength analysis of Blazar Mrk 421

The results of 8-year R-band photopolarimetric data of blazar Mrk 421 collected from February 2008 to May 2016 are presented, along with extensive multiwavelength observations covering from radio to TeV $\gamma$-rays around the flares…

High Energy Astrophysical Phenomena · Physics 2017-09-06 Nissim Fraija , Erika Benítez , David Hiriart , Marco Sorcia , Jose Manuel López , Raul Mújica , Jose Ignacio Cabrera , Jose Antonio de Diego , Miriam Rojas-Luis , Felipe Salazar-Vázquez , Antonio Galván-Gámez

Multiwavelength Observations of the Blazar VER J0521+211 During an Elevated TeV Gamma-Ray State

We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly-binned light curve is $(8.8 \pm 0.4)…

High Energy Astrophysical Phenomena · Physics 2022-08-10 The VERITAS Collaboration , The MAGIC Collaboration

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

Synchrotron emission from the blazar PG 1553+113. An analysis of its flux and polarization variability

In 2015 July 29 - September 1 the satellite XMM-Newton pointed at the BL Lac object PG 1553+133 six times, collecting data for 218 hours. During one of these epochs, simultaneous observations by the Swift satellite were requested to compare…

High Energy Astrophysical Phenomena · Physics 2019-08-13 C. M. Raiteri , F. Nicastro , A. Stamerra , M. Villata , V. M. Larionov , D. Blinov , J. A. Acosta-Pulido