Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

M. L. Ahnen; S. Ansoldi; L. A. Antonelli; P. Antoranz; A. Babic; B. Banerjee; P. Bangale; U. Barres De Almeida; J. A. Barrio; J. Becerra González; W. Bednarek; E. Bernardini; B. Biasuzzi; A. Biland; O. Blanch; S. Bonnefoy; G. Bonnoli; F. Borracci; T. Bretz; S. Buson; A. Carosi; A. Chatterjee; R. Clavero; P. Colin; E. Colombo; J. L. Contreras; J. Cortina; S. Covino; P. Da Vela; F. Dazzi; A. De Angelis; B. De Lotto; E. De Oña Wilhelmi; F. Di Pierro; A. Domínguez; D. Dominis Prester; D. Dorner; M. Doro; S. Einecke; D. Eisenacher Glawion; D. Elsaesser; A. Fernández-Barral; D. Fidalgo; M. V. Fonseca; L. Font; K. Frantzen; C. Fruck; D. Galindo; R. J. García López; M. Garczarczyk; D. Garrido Terrats; M. Gaug; P. Giammaria; N. Godinović; A. González Muñoz; D. Gora; D. Guberman; D. Hadasch; A. Hahn; Y. Hanabata; M. Hayashida; J. Herrera; J. Hose; D. Hrupec; G. Hughes; W. Idec; K. Kodani; Y. Konno; H. Kubo; J. Kushida; A. La Barbera; D. Lelas; E. Lindfors; S. Lombardi; F. Longo; M. López; R. López-Coto; P. Majumdar; M. Makariev; K. Mallot; G. Maneva; M. Manganaro; K. Mannheim; L. Maraschi; B. Marcote; M. Mariotti; M. Martínez; D. Mazin; U. Menzel; J. M. Miranda; R. Mirzoyan; A. Moralejo; E. Moretti; D. Nakajima; V. Neustroev; A. Niedzwiecki; M. Nievas Rosillo; K. Nilsson; K. Nishijima; K. Noda

doi:10.1051/0004-6361/201628447

Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

M. L. Ahnen, S. Ansoldi, L. A. Antonelli, P. Antoranz, A. Babic, B. Banerjee, P. Bangale, U. Barres De Almeida, J. A. Barrio, J. Becerra González, W. Bednarek, E. Bernardini, B. Biasuzzi, A. Biland, O. Blanch, S. Bonnefoy, G. Bonnoli, F. Borracci, T. Bretz, S. BusonA. Carosi, A. Chatterjee, R. Clavero, P. Colin, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, E. De Oña Wilhelmi, F. Di Pierro, A. Domínguez, D. Dominis Prester, D. Dorner, M. Doro, S. Einecke, D. Eisenacher Glawion, D. Elsaesser, A. Fernández-Barral, D. Fidalgo, M. V. Fonseca, L. Font, K. Frantzen, C. Fruck, D. Galindo, R. J. García López, M. Garczarczyk, D. Garrido Terrats, M. Gaug, P. Giammaria, N. Godinović, A. González Muñoz, D. Gora, D. Guberman, D. Hadasch, A. Hahn, Y. Hanabata, M. Hayashida, J. Herrera, J. Hose, D. Hrupec, G. Hughes, W. Idec, K. Kodani, Y. Konno, H. Kubo, J. Kushida, A. La Barbera, D. Lelas, E. Lindfors, S. Lombardi, F. Longo, M. López, R. López-Coto, P. Majumdar, M. Makariev, K. Mallot, G. Maneva, M. Manganaro, K. Mannheim, L. Maraschi, B. Marcote, M. Mariotti, M. Martínez, D. Mazin, U. Menzel, J. M. Miranda, R. Mirzoyan, A. Moralejo, E. Moretti, D. Nakajima, V. Neustroev, A. Niedzwiecki, M. Nievas Rosillo, K. Nilsson, K. Nishijima, K. Noda

Departament de Física

Institut de Física d'Altes Energies (IFAE)

Producció científica: Contribució a revista › Article › Recerca › Avaluat per experts

51 Cites (Scopus)

Resum

© ESO 2016. Aims. We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year timescales, which can bring additional insight on the processes responsible for its broadband emission. Methods.We observed Mrk 421 in the very high energy (VHE) -ray range with the Cherenkov telescopeMAGIC-I from March 2007 to June 2009 for a total of 96 h of effective time after quality cuts. The VHE flux variability is quantified using several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes here for the first time. The 2.3 yr long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Metshovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year timescales. Results. Mrk 421 was found in different -ray emission states during the 2.3 yr long observation period: The flux above 400 GeV spans from the minimum nightly value of (1:30:4)1011 cm2 s1 to the maximum flux, that is about 24 times higher, at (3:10:1)1010 cm2 s1. Flares and different levels of variability in the -ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Metshovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. Overall, the fractional variability increases with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and -ray photons are either the same, as expected in the synchrotron-self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades.

Idioma original	Anglès
Número d’article	A91
Revista	Astronomy and Astrophysics
Volum	593
DOIs	https://doi.org/10.1051/0004-6361/201628447
Estat de la publicació	Publicada - 1 de set. 2016

Accés al document

10.1051/0004-6361/201628447

Altres arxius i enllaços

https://www.scopus.com/pages/publications/84989907748

Mrk 421 multi-wavelength variability, 2007-2009
Ahnen, M. L. (Creador), Ansoldi, S. (Creador), Antonelli, L. A. (Creador), Antoranz, P. (Creador), Babic, A. (Creador), Banerjee, B. (Creador), Bangale, P. (Creador), Barres De Almeida, D. A. U. (Creador), Barrio, J. A. (Creador), Becerra González, G. J. (Col·laborador), Bednarek, W. (Creador), Bernardini, E. (Creador), Biasuzzi, B. (Creador), Biland, A. (Creador), Blanch, O. (Creador), Bonnefoy, S. (Creador), Bonnoli, G. (Creador), Borracci, F. (Creador), Bretz, T. (Creador), Buson, S. (Creador), Carosi, A. (Creador), Chatterjee, A. (Creador), Clavero, R. (Creador), Colin, P. (Creador), Colombo, E. (Creador), Contreras, J. L. (Creador), Cortina, J. (Creador), Covino, S. (Creador), Da Vela, V. P. (Creador), Dazzi, F. (Creador), De Angelis, A. A. (Creador), De Lotto, L. B. (Creador), De Oña Wilhelmi, O. W. E. (Col·laborador), Di Pierro, P. F. (Creador), Domínguez, A. (Col·laborador), Dominis Prester, P. D. (Creador), Dorner, D. (Creador), Doro, M. (Creador), Einecke, S. (Creador), Eisenacher Glawion, G. D. (Creador), Elsaesser, D. (Creador), Fernández-Barral, A. (Col·laborador), Fidalgo, D. (Creador), Fonseca, M. V. (Creador), Font Guiteras, L. (Creador), Frantzen, K. (Creador), Fruck, C. (Creador), Galindo, D. (Creador), García López, L. R. J. (Col·laborador), Garczarczyk, M. (Creador), Garrido Terrats, T. D. (Creador), Gaug ., M. (Creador), Giammaria, P. (Creador), Godinović, N. (Col·laborador), González Muñoz, M. A. (Col·laborador), Gora, D. (Creador), Guberman, D. (Creador), Hadasch, D. (Creador), Hahn, A. (Creador), Hanabata, Y. (Creador), Hayashida, M. (Creador), Herrera, J. (Creador), Hose, J. (Creador), Hrupec, D. (Creador), Hughes, G. (Creador), Idec, W. (Creador), Kodani, K. (Creador), Konno, Y. (Creador), Kubo, H. (Creador), Kushida, J. (Creador), La Barbera, B. A. (Creador), Lelas, D. (Creador), Lindfors, E. (Creador), Lombardi, S. (Creador), Longo, F. (Creador), López, M. (Col·laborador), López-Coto, R. (Col·laborador), Majumdar, P. (Creador), Makariev, M. (Creador), Mallot, K. (Creador), Maneva, G. (Creador), Manganaro, M. (Creador), Mannheim, K. (Creador), Maraschi, L. (Creador), Marcote, B. (Creador), Mariotti, M. (Creador), Martínez, M. (Col·laborador), Mazin, D. (Creador), Menzel, U. (Creador), Miranda, J. M. (Creador), Mirzoyan, R. (Creador), Moralejo, A. (Creador), Moretti, E. (Creador), Nakajima, D. (Creador), Neustroev, V. (Creador), Niedzwiecki, A. (Creador), Nievas Rosillo, R. M. (Creador), Nilsson, K. (Creador), Nishijima, K. (Creador), Noda, K. (Creador), Nogués, L. (Col·laborador), Orito, R. (Creador), Overkemping, A. (Creador), Paiano, S. (Creador), Palacio, J. (Creador), Palatiello, M. (Creador), Paneque, D. (Creador), Paoletti, R. (Creador), Paredes, J. M. (Creador), Paredes-Fortuny, X. (Creador), Pedaletti, G. (Creador), Perri, L. (Creador), Persic, M. (Creador), Poutanen, J. (Creador), Prada Moroni, M. P. G. (Creador), Prandini, E. (Creador), Puljak, I. (Creador), Rhode, W. (Creador), Ribó, M. (Col·laborador), Rico, J. (Creador), Rodriguez Garcia, G. J. (Creador), Saito, T. (Creador), Satalecka, K. (Creador), Schultz, C. (Creador), Schweizer, T. (Creador), Shore, S. N. (Creador), Sillanpää, A. (Col·laborador), Sitarek, J. (Creador), Snidaric, I. (Creador), Sobczynska, D. (Creador), Stamerra, A. (Creador), Steinbring, T. (Creador), Strzys, M. (Creador), Takalo, L. (Creador), Takami, H. (Creador), Tavecchio, F. (Creador), Temnikov, P. (Creador), Terzić, T. (Col·laborador), Tescaro, D. (Creador), Teshima, M. (Creador), Thaele, J. (Creador), Torres, D. F. (Creador), Toyama, T. (Creador), Treves, A. (Creador), Verguilov, V. (Creador), Vovk, I. (Creador), Ward, J. E. (Creador), Will, M. (Creador), Wu, M. H. (Creador), Blinov, D. A. (Creador), Chen, W. P. (Creador), Efimova, N. V. (Creador), Forné, E. (Col·laborador), Grishina, T. S. (Creador), Hovatta, T. (Creador), Jordan, B. (Creador), Kimeridze, G. N. (Creador), Kopatskaya, E. N. (Creador), Koptelova, E. (Creador), Kurtanidze, O. M. (Creador), Kurtanidze, S. O. (Creador), Lähteenmäki, A. (Col·laborador), Larionov, V. M. (Creador), Larionova, E. G. (Creador), Larionova, L. V. (Creador), Ligustri, R. (Creador), McBreen, B. (Col·laborador), Morozova, D. A. (Creador), Nikolashvili, M. G. (Creador), Raiteri, C. M. (Creador), Ros, J. A. (Creador), Sadun, A. C. (Creador), Sigua, L. A. (Creador), Tornikoski, M. (Creador), Troitsky, I. S. (Creador) & Villata, M. (Creador), Centre de Donnees Strasbourg (CDS), 2016
DOI: 10.26093/cds/vizier.35930091, https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/593/A91
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Com citar-ho

Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., Barres De Almeida, U., Barrio, J. A., Becerra González, J., Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., ... Noda, K. (2016). Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009. Astronomy and Astrophysics, 593, Article A91. https://doi.org/10.1051/0004-6361/201628447

@article{852b1c102f094b3f8c47f0f9842c637c,

title = "Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009",

abstract = "{\textcopyright} ESO 2016. Aims. We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year timescales, which can bring additional insight on the processes responsible for its broadband emission. Methods.We observed Mrk 421 in the very high energy (VHE) -ray range with the Cherenkov telescopeMAGIC-I from March 2007 to June 2009 for a total of 96 h of effective time after quality cuts. The VHE flux variability is quantified using several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes here for the first time. The 2.3 yr long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Metshovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year timescales. Results. Mrk 421 was found in different -ray emission states during the 2.3 yr long observation period: The flux above 400 GeV spans from the minimum nightly value of (1:30:4)1011 cm2 s1 to the maximum flux, that is about 24 times higher, at (3:10:1)1010 cm2 s1. Flares and different levels of variability in the -ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Metshovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. Overall, the fractional variability increases with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and -ray photons are either the same, as expected in the synchrotron-self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades.",

keywords = "Astroparticle physics, BL Lacertae objects: individual: Markarian 421, Radiation mechanisms: non-thermal",

author = "Ahnen, \{M. L.\} and S. Ansoldi and Antonelli, \{L. A.\} and P. Antoranz and A. Babic and B. Banerjee and P. Bangale and \{Barres De Almeida\}, U. and Barrio, \{J. A.\} and \{Becerra Gonz{\'a}lez\}, J. and W. Bednarek and E. Bernardini and B. Biasuzzi and A. Biland and O. Blanch and S. Bonnefoy and G. Bonnoli and F. Borracci and T. Bretz and S. Buson and A. Carosi and A. Chatterjee and R. Clavero and P. Colin and E. Colombo and Contreras, \{J. L.\} and J. Cortina and S. Covino and \{Da Vela\}, P. and F. Dazzi and \{De Angelis\}, A. and \{De Lotto\}, B. and \{De O{\~n}a Wilhelmi\}, E. and \{Di Pierro\}, F. and A. Dom{\'i}nguez and \{Dominis Prester\}, D. and D. Dorner and M. Doro and S. Einecke and \{Eisenacher Glawion\}, D. and D. Elsaesser and A. Fern{\'a}ndez-Barral and D. Fidalgo and Fonseca, \{M. V.\} and L. Font and K. Frantzen and C. Fruck and D. Galindo and \{Garc{\'i}a L{\'o}pez\}, \{R. J.\} and M. Garczarczyk and \{Garrido Terrats\}, D. and M. Gaug and P. Giammaria and N. Godinovi{\'c} and \{Gonz{\'a}lez Mu{\~n}oz\}, A. and D. Gora and D. Guberman and D. Hadasch and A. Hahn and Y. Hanabata and M. Hayashida and J. Herrera and J. Hose and D. Hrupec and G. Hughes and W. Idec and K. Kodani and Y. Konno and H. Kubo and J. Kushida and \{La Barbera\}, A. and D. Lelas and E. Lindfors and S. Lombardi and F. Longo and M. L{\'o}pez and R. L{\'o}pez-Coto and P. Majumdar and M. Makariev and K. Mallot and G. Maneva and M. Manganaro and K. Mannheim and L. Maraschi and B. Marcote and M. Mariotti and M. Mart{\'i}nez and D. Mazin and U. Menzel and Miranda, \{J. M.\} and R. Mirzoyan and A. Moralejo and E. Moretti and D. Nakajima and V. Neustroev and A. Niedzwiecki and \{Nievas Rosillo\}, M. and K. Nilsson and K. Nishijima and K. Noda",

year = "2016",

month = sep,

day = "1",

doi = "10.1051/0004-6361/201628447",

language = "English",

volume = "593",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Ahnen, ML, Ansoldi, S, Antonelli, LA, Antoranz, P, Babic, A, Banerjee, B, Bangale, P, Barres De Almeida, U, Barrio, JA, Becerra González, J, Bednarek, W, Bernardini, E, Biasuzzi, B, Biland, A, Blanch, O, Bonnefoy, S, Bonnoli, G, Borracci, F, Bretz, T, Buson, S, Carosi, A, Chatterjee, A, Clavero, R, Colin, P, Colombo, E, Contreras, JL, Cortina, J, Covino, S, Da Vela, P, Dazzi, F, De Angelis, A, De Lotto, B, De Oña Wilhelmi, E, Di Pierro, F, Domínguez, A, Dominis Prester, D, Dorner, D, Doro, M, Einecke, S, Eisenacher Glawion, D, Elsaesser, D, Fernández-Barral, A, Fidalgo, D, Fonseca, MV, Font, L, Frantzen, K, Fruck, C, Galindo, D, García López, RJ, Garczarczyk, M, Garrido Terrats, D, Gaug, M, Giammaria, P, Godinović, N, González Muñoz, A, Gora, D, Guberman, D, Hadasch, D, Hahn, A, Hanabata, Y, Hayashida, M, Herrera, J, Hose, J, Hrupec, D, Hughes, G, Idec, W, Kodani, K, Konno, Y, Kubo, H, Kushida, J, La Barbera, A, Lelas, D, Lindfors, E, Lombardi, S, Longo, F, López, M, López-Coto, R, Majumdar, P, Makariev, M, Mallot, K, Maneva, G, Manganaro, M, Mannheim, K, Maraschi, L, Marcote, B, Mariotti, M, Martínez, M, Mazin, D, Menzel, U, Miranda, JM, Mirzoyan, R, Moralejo, A, Moretti, E, Nakajima, D, Neustroev, V, Niedzwiecki, A, Nievas Rosillo, M, Nilsson, K, Nishijima, K & Noda, K 2016, 'Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009', Astronomy and Astrophysics, vol. 593, A91. https://doi.org/10.1051/0004-6361/201628447

TY - JOUR

T1 - Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

AU - Ahnen, M. L.

AU - Ansoldi, S.

AU - Antonelli, L. A.

AU - Antoranz, P.

AU - Babic, A.

AU - Banerjee, B.

AU - Bangale, P.

AU - Barres De Almeida, U.

AU - Barrio, J. A.

AU - Becerra González, J.

AU - Bednarek, W.

AU - Bernardini, E.

AU - Biasuzzi, B.

AU - Biland, A.

AU - Blanch, O.

AU - Bonnefoy, S.

AU - Bonnoli, G.

AU - Borracci, F.

AU - Bretz, T.

AU - Buson, S.

AU - Carosi, A.

AU - Chatterjee, A.

AU - Clavero, R.

AU - Colin, P.

AU - Colombo, E.

AU - Contreras, J. L.

AU - Cortina, J.

AU - Covino, S.

AU - Da Vela, P.

AU - Dazzi, F.

AU - De Angelis, A.

AU - De Lotto, B.

AU - De Oña Wilhelmi, E.

AU - Di Pierro, F.

AU - Domínguez, A.

AU - Dominis Prester, D.

AU - Dorner, D.

AU - Doro, M.

AU - Einecke, S.

AU - Eisenacher Glawion, D.

AU - Elsaesser, D.

AU - Fernández-Barral, A.

AU - Fidalgo, D.

AU - Fonseca, M. V.

AU - Font, L.

AU - Frantzen, K.

AU - Fruck, C.

AU - Galindo, D.

AU - García López, R. J.

AU - Garczarczyk, M.

AU - Garrido Terrats, D.

AU - Gaug, M.

AU - Giammaria, P.

AU - Godinović, N.

AU - González Muñoz, A.

AU - Gora, D.

AU - Guberman, D.

AU - Hadasch, D.

AU - Hahn, A.

AU - Hanabata, Y.

AU - Hayashida, M.

AU - Herrera, J.

AU - Hose, J.

AU - Hrupec, D.

AU - Hughes, G.

AU - Idec, W.

AU - Kodani, K.

AU - Konno, Y.

AU - Kubo, H.

AU - Kushida, J.

AU - La Barbera, A.

AU - Lelas, D.

AU - Lindfors, E.

AU - Lombardi, S.

AU - Longo, F.

AU - López, M.

AU - López-Coto, R.

AU - Majumdar, P.

AU - Makariev, M.

AU - Mallot, K.

AU - Maneva, G.

AU - Manganaro, M.

AU - Mannheim, K.

AU - Maraschi, L.

AU - Marcote, B.

AU - Mariotti, M.

AU - Martínez, M.

AU - Mazin, D.

AU - Menzel, U.

AU - Miranda, J. M.

AU - Mirzoyan, R.

AU - Moralejo, A.

AU - Moretti, E.

AU - Nakajima, D.

AU - Neustroev, V.

AU - Niedzwiecki, A.

AU - Nievas Rosillo, M.

AU - Nilsson, K.

AU - Nishijima, K.

AU - Noda, K.

PY - 2016/9/1

Y1 - 2016/9/1

N2 - © ESO 2016. Aims. We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year timescales, which can bring additional insight on the processes responsible for its broadband emission. Methods.We observed Mrk 421 in the very high energy (VHE) -ray range with the Cherenkov telescopeMAGIC-I from March 2007 to June 2009 for a total of 96 h of effective time after quality cuts. The VHE flux variability is quantified using several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes here for the first time. The 2.3 yr long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Metshovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year timescales. Results. Mrk 421 was found in different -ray emission states during the 2.3 yr long observation period: The flux above 400 GeV spans from the minimum nightly value of (1:30:4)1011 cm2 s1 to the maximum flux, that is about 24 times higher, at (3:10:1)1010 cm2 s1. Flares and different levels of variability in the -ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Metshovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. Overall, the fractional variability increases with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and -ray photons are either the same, as expected in the synchrotron-self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades.

AB - © ESO 2016. Aims. We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year timescales, which can bring additional insight on the processes responsible for its broadband emission. Methods.We observed Mrk 421 in the very high energy (VHE) -ray range with the Cherenkov telescopeMAGIC-I from March 2007 to June 2009 for a total of 96 h of effective time after quality cuts. The VHE flux variability is quantified using several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes here for the first time. The 2.3 yr long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Metshovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year timescales. Results. Mrk 421 was found in different -ray emission states during the 2.3 yr long observation period: The flux above 400 GeV spans from the minimum nightly value of (1:30:4)1011 cm2 s1 to the maximum flux, that is about 24 times higher, at (3:10:1)1010 cm2 s1. Flares and different levels of variability in the -ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Metshovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. Overall, the fractional variability increases with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and -ray photons are either the same, as expected in the synchrotron-self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades.

KW - Astroparticle physics

KW - BL Lacertae objects: individual: Markarian 421

KW - Radiation mechanisms: non-thermal

UR - https://www.scopus.com/pages/publications/84989907748

U2 - 10.1051/0004-6361/201628447

DO - 10.1051/0004-6361/201628447

M3 - Article

SN - 0004-6361

VL - 593

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A91

ER -

Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

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Mrk 421 multi-wavelength variability, 2007-2009

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